JP2000248953A - Supercharge pressure control device for engine with supercharger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent generation of a trouble in a transmission due to excessive drive force by decreasing a target supercharge pressure, when stepping up an accelerator with a car in a stopped condition by stepping in a brake with the transmission left as in a running range, related to an engine with supercharger successively providing in an output shaft the transmission automatically changing a speed change shift based on a speed change characteristic preset in accordance with operation conditions. SOLUTION: Based on an engine speed and a throttle opening, after a basic target supercharge pressure TPTAGTM is set, a car speed VSP is compared with a preset value TBSTSP corresponding to a car stopped condition (S215), when a relation is VSP<TBSTSP, a gear position correction coefficient (speed change ratio correction coefficient) KGP for decreasingly correcting the basic target supercharge pressure TPTAGTM according to a gear position GEAR is set (S216 to S224). The basic target supercharge pressure TPTAGTM is corrected by the gear position correction coefficient KGP or the like, and a target supercharge pressure TPTAGT is calculated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a primary turbocharger and a secondary turbocharger which are arranged in parallel in an intake and exhaust system of an engine, and a shift is performed based on a shift characteristic preset according to an operating state. The supercharged engine is equipped with a supercharger engine with a transmission that automatically changes gears connected to the output shaft, and the supercharging pressure is controlled in a single turbo state in which only the primary turbocharger is supercharged when the engine is in a low speed range. In the high-speed region of the engine, the supercharging pressure control device of the supercharged engine that controls the supercharging pressure in the twin turbo state in which both the turbochargers are supercharged together. The supercharging pressure of an engine with a turbocharger that can prevent problems caused by excessive driving force applied to the transmission even when the accelerator is depressed with the brake depressed and the vehicle stopped On your system.

[0002]

2. Description of the Related Art In recent years, a primary turbocharger and a secondary turbocharger are arranged in parallel in an intake and exhaust system of an engine, and an intake control valve is provided in an intake and exhaust system connected to the secondary turbocharger. 2. Description of the Related Art An engine with a supercharger (so-called sequential turbo engine) has been proposed in which an exhaust control valve is provided, and both control valves are opened and closed, so that the operating number of the supercharger is appropriately switched according to an operation range.

In this turbocharged engine, the operating region is divided into a single turbo region in a low speed region and a twin turbo region in a high speed region. When the operating region is in the single turbo region, the intake control valve is closed. When the exhaust control valve is closed or slightly opened (to pre-rotate the secondary turbocharger) to operate only the primary turbocharger and the operation region is in the twin turbo region, both control valves are operated. Are opened together to operate the turbochargers in a supercharging manner, thereby improving the output performance from a low speed range to a high speed range.

Conventionally, there is a prior art in Japanese Patent Application Laid-Open No. 6-129253 for supercharging pressure control of an engine with a supercharger. In this prior art, a target supercharging pressure set according to an operation state and a target supercharging pressure are set. Calculates the deviation from the actual boost pressure, compares the absolute value of the deviation with the set value, sets the proportional control amount and the integral control amount in the proportional integral control, and the actual boost pressure follows the target boost pressure Feedback control.

[0005]

However, in an engine with a supercharger in which a transmission for automatically changing the gear position based on a shift characteristic set in advance according to the operating state is connected to the output shaft, If the brake is depressed and the accelerator pedal is depressed while the vehicle is in the travel range, an excessive driving force may be applied to the transmission, which may cause a problem.

[0006] In particular, if the stall for fully opening the accelerator is performed in a stopped state where the brake is depressed in the traveling range, the same supercharging pressure as in the fully opened traveling is applied, and a failure occurs in the transmission due to excessive driving force. There is a strong possibility of doing.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has a supercharger in which a transmission for automatically changing a gear position based on a shift characteristic set in advance according to an operation state is connected to an output shaft. When the accelerator is depressed while the transmission is in the travel range and the brake is depressed while the transmission is in the travel range, the target boost pressure is reduced to prevent the transmission from malfunctioning due to excessive driving force. It is an object of the present invention to provide a supercharging pressure control device for a supercharged engine.

[0008]

In order to achieve the above object, according to the first aspect of the present invention, a primary turbocharger and a secondary turbocharger are arranged in parallel in an intake and exhaust system of an engine, and the engine is operated in advance. An engine with a supercharger having a transmission connected to the output shaft that automatically changes the gear position based on the shift characteristics set according to the state, and only the primary turbocharger at the engine low speed range A supercharging pressure control device for an engine with a supercharger that performs supercharging pressure control in a single turbo state in which a supercharging operation is performed, and performs supercharging pressure control in a twin turbo state in which both turbochargers are supercharged when the engine is in a high-speed region. In the above, based on the engine operating state, the basic target supercharging pressure when controlling the supercharging pressure in the single turbo state, and the basic target supercharging pressure when controlling the supercharging pressure in the twin turbo state, A basic target supercharging pressure setting means for setting and correcting the basic target supercharging pressure in accordance with the gear ratio of the transmission when it is determined that the vehicle speed is lower than a set value in a single turbo state. A gear ratio correction coefficient setting means for setting a gear ratio correction coefficient of, and in a single turbo state, set a target supercharging pressure by correcting the basic target supercharging pressure corresponding to the single turbo state by the gear ratio correction coefficient, In the twin turbo state, there is provided target boost pressure setting means for setting the target boost pressure without correcting the basic target boost pressure corresponding to the twin turbo state by the above-mentioned gear ratio correction coefficient.

According to a second aspect of the present invention, in the first aspect, the speed ratio correction coefficient setting means decreases the speed ratio correction coefficient with respect to the basic target supercharging pressure as the speed ratio increases. The correction amount is set to be large.

That is, according to the first aspect of the present invention, a basic target supercharging pressure for controlling the supercharging pressure in the single turbo state and a supercharging pressure for controlling the supercharging pressure in the twin turbo state are based on the engine operating state. The basic target supercharging pressure is set as the basic target supercharging pressure corresponding to the engine warm-up completion state, and when it is determined that the vehicle speed is lower than the set value in the single turbo state and the vehicle is stopped, the basic target supercharging pressure is set. A gear ratio correction coefficient is set to reduce the supply pressure in accordance with the gear ratio of the transmission for automatically changing the gear position based on gear characteristics set in advance according to the operating state. In the single turbo state, the target supercharging pressure corresponding to the single turbo state is corrected by the gear ratio correction coefficient to set the target supercharging pressure. In the twin turbo state, the basic target supercharging pressure corresponding to the twin turbo state is set. The target boost pressure is set without correcting the pressure with the gear ratio correction coefficient.

In this case, according to the second aspect of the invention, the speed ratio correction coefficient is set such that the larger the speed ratio, the larger the amount of reduction correction to the basic target supercharging pressure.

[0012]

An embodiment of the present invention will be described below with reference to the drawings. FIGS. 1 to 50 relate to an embodiment of the present invention. FIG. 1 is a flowchart showing jobs of a turbo switching control routine and a supercharging pressure control routine. FIGS. 2 to 6 are flowcharts of a turbo switching control routine. ~
FIG. 12 is a flowchart of a supercharging pressure control routine, and FIG.
17 is a flowchart of a DUTY1 calculation routine,
18 to 21 are flowcharts of the DUTY2 calculation routine, FIG. 22 is an explanatory diagram showing each switching determination value, and the relationship between the single turbo region and the twin turbo region, and FIG. FIG. 24 is an explanatory diagram of an exhaust control valve small opening control mode region, FIG. 25 is a conceptual diagram of an exhaust control valve opening delay time setting table, and FIG. 26 is an intake control valve opening delay time setting table. FIG. 27 is a conceptual diagram of an intake control valve opening differential pressure setting table, FIG. 28 is a conceptual diagram of a determination value atmospheric pressure correction coefficient table, and FIG. 29 shows the relationship between each determination line and the primary turbo overspeed region. FIG. 30 is an explanatory diagram showing the atmospheric pressure correction state of each determination line, FIG. 31 is a conceptual diagram of a twin → single atmospheric pressure correction coefficient table, and FIG. Conceptual view of time determination value table, Fig. 3
3 is a time chart showing a switching state from a single turbo to a twin turbo, FIG. 34 is a time chart showing a switching state from a twin turbo to a single turbo, and FIG. 35 shows output characteristics between a single turbo and a twin turbo. 36 is an explanatory diagram showing a linear function relationship between atmospheric pressure and a supercharging atmospheric pressure correction coefficient, FIG. 37 is an explanatory diagram showing a linear function relationship between cooling water temperature and a water temperature correction coefficient, and FIG. FIG. 39 is a conceptual diagram of an initial value setting table, FIG. 40 is a conceptual diagram of a DUTY1 initial value setting table, FIG. 41 is a conceptual diagram of an upper limit value setting table, and FIG. Explanatory diagram of the pressure feedback control state,
FIG. 43 is an explanatory diagram showing the state of the actual supercharging pressure in the special state and the normal state. FIG. 44 is a time chart showing the state of switching from the primary wastegate control mode to the exhaust control valve small opening control mode under the single turbo state. FIG. 45 is a time chart showing a switching state from the exhaust control valve small opening control mode to the primary wastegate control mode under the single turbo state, and FIG. 46 is a switching state from the primary wastegate control mode of the single turbo to the twin turbo. FIG. 47 is a time chart showing the switching state of the single turbo exhaust control valve small opening control mode to the twin turbo, and FIG. 48 is a time chart showing the switching state of the twin turbo to the single turbo control mode. 49 is an overall configuration diagram of an engine with a supercharger, FIG. Is a circuit diagram of an electronic control system.

FIG. 49 shows the overall configuration of an engine with a supercharger to which the present invention is applied. Reference numeral 1 denotes a horizontally opposed engine (a four-cylinder engine in this embodiment). In the left and right banks 3 and 4 of the crankcase 2 of the engine 1, a combustion chamber 5, an intake port 6, an exhaust port 7, a spark plug 8,
The valve train 9 and the like are provided, and the left bank 3 is provided with # 2 and # 4 cylinders, and the right bank 4 is provided with # 1 and # 3 cylinders.

Further, a primary turbocharger 40 and a secondary turbocharger 50 are respectively provided immediately after the left and right banks 3 and 4 due to the shortened shape of the engine. As an exhaust system, a common exhaust pipe 10 from both the left and right banks 3 and 4 is used as a turbine 40 of both turbochargers 40 and 50.
The exhaust pipes 11 from the turbines 40a and 50a join one exhaust pipe 12 and communicate with the catalytic converter 13 and the muffler 14.

The primary turbocharger 40 is a small-capacity, low-speed type having a large supercharging capacity in a low to medium speed range, whereas the secondary turbocharger 50 has a large supercharging capacity in a medium to high speed range. High capacity, high speed type. For this reason, the primary turbocharger 40 has a smaller capacity, so that the exhaust resistance increases.

On the other hand, as an intake system, an air cleaner 15 is used.
The intake pipes 16 and 17 branched into two from the downstream of the compressors 40b and 50 of the turbochargers 40 and 50, respectively.
b, and the intake pipes 18, 19 from the compressors 40b, 50b are connected to the intercooler 20.
The air is communicated from the intercooler 20 to the chamber 22 through a throttle body 27 having a throttle valve 21, and from the chamber 22 to the intake ports 6 of the respective cylinders of the left and right banks 3 and 4 via an intake manifold 23.

As an idle control system, a bypass passage 24 that bypasses the throttle valve 21 and communicates the intake pipe immediately downstream of the air cleaner 15 with the intake manifold 23.
In addition, an idle control (ISC) valve 25 and a check valve 26 that opens with a negative pressure are provided to control the amount of intake air during idling or deceleration.

As a fuel system, an intake manifold 2 is provided.
An injector 30 is disposed immediately upstream of the intake port 6 in each cylinder 3 and has a fuel pump 31 having a fuel pump 31.
A fuel passage 33 from the fuel tank 2 is provided with a filter 34 and a fuel pressure regulator 35 and communicates with the injector 30.

The fuel pressure regulator 35 adjusts according to the intake pressure in the intake manifold 23, thereby keeping the fuel pressure supplied to the injector 30 constant with respect to the intake pressure. The injector 30 can be driven by the pulse width of the injection signal from the engine control device 100 to control the fuel injection amount. Each ignition plug 8 is used as an ignition system.
Each ignition coil 8a is connected so that an ignition signal from the igniter 36 is input.

Here, the operation system of the primary turbocharger 40 will be described. Primary turbocharger 40
Is driven to rotate the compressor 40b by the energy of the exhaust gas introduced into the turbine 40a, so that the air is sucked and pressurized to constantly supercharge. A primary wastegate valve 41 provided with a primary wastegate valve operating actuator 42, which is a diaphragm type actuator, is provided on the turbine 40a side. A control pressure passage 44 directly downstream of the compressor 40b communicates with an orifice 48 to the pressure chamber of the primary wastegate valve operating actuator 42. When the supercharging pressure rises above a set value, the primary wastegate valve is responsive. It is communicated to open 41.

The control pressure passage 44 further has a primary wastegate control duty solenoid valve D.L. which leaks the supercharging pressure upstream of the compressor 40b. SOL.
The primary wastegate control duty solenoid valve D. SOL. A predetermined control pressure is generated by 1 and acts on the primary wastegate valve actuating actuator 42 to change the opening degree of the primary wastegate valve 41 to control the supercharging pressure. Here, the primary wastegate control duty solenoid valve D. SOL. 1
Is operated by a duty signal from the engine control device 100 described later, and when the duty ratio of the duty signal is small, the primary wastegate valve 4 is operated at a high control pressure.
1, the supercharging pressure is reduced by increasing the opening degree, and as the duty ratio increases, the control pressure is reduced by increasing the leak amount, and the supercharging pressure is increased by decreasing the opening degree of the primary wastegate valve 41.

On the other hand, in order to prevent a decrease in compressor rotation and the generation of intake noise when the throttle valve is rapidly closed, a portion between the outlet side of the intercooler 20 near the throttle valve 21 and the upstream of the compressor 40b is provided downstream of the compressor 40b. Is connected to the bypass passage 46. An air bypass valve 45 is provided in the bypass passage 46 so as to introduce a manifold negative pressure through the passage 47 when the throttle valve is suddenly closed, and to quickly open and leak pressurized air trapped downstream of the compressor 40b.

Next, the operation system of the secondary turbocharger 50 will be described. Similarly, the secondary turbocharger 50 is configured to supercharge the turbine 50a and the compressor 50b by rotating the turbine 50a by exhaust gas, and a secondary wastegate valve 51 having an actuator 52 is provided on the turbine 50a side.

The exhaust pipe 10 upstream of the turbine 50a
Is provided with a downstream opening type exhaust control valve 53 provided with an exhaust control valve actuating actuator 54 which is a diaphragm type actuator, and a butterfly type intake control valve 55 provided with a similar actuator 56 downstream of the compressor 50b. Is provided, and a supercharging pressure relief valve 57 is provided in a relief passage 58 that communicates between the upstream and downstream of the compressor 50b.

As a pressure operation system for each of the valves 51, 53, 55, and 57, a switching solenoid valve SOL. For a boost pressure relief valve for opening and closing the boost pressure relief valve 57 is provided. 1, an intake control valve switching solenoid valve SOL. 2. First and second exhaust control valve switching solenoid valves SOL. D. 3, 4, exhaust control valve small opening control duty solenoid valve for controlling small opening of exhaust control valve 53 SOL. 2 and a secondary wastegate valve switching solenoid valve SOL. W is provided. Further, each switching solenoid valve SOL. A surge tank 60 as a negative pressure source for 1, 2, 4 is connected to the intake manifold 23 through a passage 61 having a check valve 62,
When the throttle valve 21 is fully closed, a negative pressure is stored and a pulsating pressure is buffered.

Each switching solenoid valve SOL. W, SOL.
1-4 are ON and OFF from the engine control device 100
According to the signal, the positive pressure from the passage 65 communicating with the intake control valve 55 upstream, the negative pressure via the negative pressure passage 63 from the surge tank 60, and the positive pressure passage 64 communicating with the downstream of the intake control valve 55.
a, 64b is selected and guided to the actuator side through the control pressure passages 70a to 74a, and the secondary wastegate valve 51, the supercharging pressure relief valve 57, and the control valves 55 and 53 are controlled. Activate. Further, the exhaust control valve small opening control duty solenoid valve D. SOL. 2
Is a positive pressure chamber 54a of the exhaust control valve actuating actuator 54 in response to a duty signal from the engine control device 100.
, And the exhaust control valve 53 is controlled to be small open.

Switching solenoid valve for boost pressure relief valve SO
L. When the energization is turned off, the positive pressure passage 64a is closed and the negative pressure passage 63 is opened, and the negative pressure is applied to the pressure chamber in which the spring of the supercharging pressure relief valve 57 is mounted via the control pressure passage 71a. To open the boost pressure relief valve 57 against the urging force of the spring. When it is turned on, the negative pressure passage 63 is closed, the positive pressure passage 64a is opened, and the positive pressure is introduced into the pressure chamber of the supercharging pressure relief valve 57 to close the supercharging pressure relief valve 57.

The switching solenoid valve SOL. 2
Is turned off, the atmosphere port is closed, the side of the negative pressure passage 63 is opened, and the actuator 56 is controlled via the control pressure passage 72a.
The intake control valve 55 is closed against the urging force of the spring by introducing a negative pressure into the pressure chamber in which the
When this is done, the side of the negative pressure passage 63 is closed, the atmosphere port is opened, and the atmospheric pressure is guided to the pressure chamber of the actuator 56, so that the intake control valve 55 is opened by the urging force of the spring in the pressure chamber.

The switching solenoid valve for secondary wastegate valve SOL. W is turned off only when the engine control device 100 determines that high-octane gasoline is used based on the ignition advance amount and the like, and is turned on when it is determined that regular gasoline is used. The secondary solenoid valve switching solenoid valve SOL. W is turned off to close the passage 65 communicating upstream of the intake control valve 55, open the atmospheric port, and introduce atmospheric pressure to the actuator 52 through the control pressure passage 70a.
The secondary wastegate valve 51 is closed by the urging force of the spring disposed therein. Further, when turned on, the atmosphere port is closed and the passage 65 side is opened, and the supercharging pressure downstream of the secondary turbocharger 50 when both the turbochargers 40 and 50 are operated is guided to the actuator 52, and according to this supercharging pressure, When the secondary wastegate valve 51 is opened, the supercharging pressure is relatively reduced when using regular gasoline compared to when using high-octane gasoline.

Further, the first exhaust control valve switching solenoid valve SOL. The control pressure passage 73a from the exhaust control valve 53
A second exhaust control valve switching solenoid valve SO is provided in the positive pressure chamber 54a of the exhaust control valve
L. The control pressure passages 74a from the pressure control valves 4 communicate with the negative pressure chambers 54b containing the springs of the actuator 54 for operating the exhaust control valve.

Then, both switching solenoid valves SOL. 3,
4 are both OFF, the first exhaust control valve switching solenoid valve SOL. 3 closes the positive pressure passage 64b and opens the atmosphere port, and the second exhaust control valve switching solenoid valve SOL.
Numeral 4 indicates that the two chambers 54a, 54 of the exhaust control valve actuating actuator 54
b is released to the atmosphere, and the exhaust control valve 53 is fully closed by the urging force of the spring provided in the negative pressure chamber 54b.

The two-way solenoid valve SOL. 3,4
Are both ON, the atmosphere ports are closed, and the first exhaust control valve switching solenoid valve SOL. 3 is a positive pressure passage 6
4b, open the second exhaust control valve switching solenoid valve S
OL. 4 opens the side of the negative pressure passage 63 to guide a positive pressure to the positive pressure chamber 54a and a negative pressure to the negative pressure chamber 54b of the actuator 54 for operating the exhaust control valve, and to exhaust the exhaust control valve against the urging force of the spring. Fully open 53.

First exhaust control valve switching solenoid valve SO
L. An orifice 67 is provided in the control pressure passage 73a from the third passage 3, and a leak passage 66 is connected to the downstream side of the orifice 67 and the intake pipe 16, and the above-described exhaust control valve small opening control duty solenoid valve D . SO
L. 2 are provided.

Then, the first exhaust control valve switching solenoid valve SOL. 3 is ON, the positive pressure is supplied to the positive pressure chamber 54a of the exhaust control valve actuating actuator 54 and the negative pressure chamber 54
b is opened to the atmosphere, the exhaust control valve small opening control duty solenoid valve D. SOL. 2, the positive pressure is leaked and the exhaust control valve 53 is slightly opened.

Here, the exhaust control valve small opening control duty solenoid valve D. SOL. 2 is an engine control device 100
When the duty ratio of the duty signal from the controller is large, the positive pressure acting on the positive pressure chamber 54a is reduced due to the increase in the leak amount, and the opening degree of the exhaust control valve 53 is reduced. As the duty ratio decreases, the leak amount is reduced. The positive pressure is kept high, and the opening of the exhaust control valve 53 is increased. When the engine operating region is in a predetermined exhaust control valve small opening control mode region under the single turbo state, the exhaust control valve small opening control duty solenoid valve D.D. SOL. 2, the supercharging pressure is feedback-controlled based on the opening degree of the exhaust control valve 53, and the exhaust control valve 53 is slightly opened with the supercharging pressure control.

Next, various sensors will be described. A differential pressure sensor 80 is provided to detect a differential pressure between upstream and downstream of the intake control valve 55, and an absolute pressure sensor 81 is controlled by an intake pipe pressure / atmospheric pressure switching solenoid valve 76 to intake pipe pressure (intake pressure in the intake manifold 23). ) And the atmospheric pressure are selected and detected. A knock sensor 82 is attached to the engine 1, a coolant temperature sensor 83 faces a cooling water passage communicating the left and right banks 3 and 4, and an O 2 sensor 84 faces the exhaust pipe 10. Further, a throttle opening sensor 85 for detecting a throttle opening is connected to the throttle valve 21, and an intake air amount sensor 86 is provided immediately downstream of the air cleaner 15.

A crank rotor 90 is mounted on a crankshaft 1a supported by the engine 1. A crank angle sensor 87 such as an electromagnetic pickup is provided on the outer periphery of the crank rotor 90. Further, a cam rotor 91 connected to a cam shaft in the valve train 9
, A cam angle sensor 88 composed of an electromagnetic pickup or the like for cylinder identification is provided in opposition.

Crank angle sensor 87, cam angle sensor 88
In this case, protrusions (or slits) formed on the crank rotor 90 and the cam rotor 91 at predetermined intervals are detected with the operation of the engine, and a crank pulse and a cam pulse are output. Then, in the engine control device 100,
The engine speed is calculated from the crank pulse interval time (projection detection interval), the ignition timing, the fuel injection start timing, and the like are calculated. Further, the cylinder is determined from the input pattern of the crank pulse and the cam pulse.

Next, the configuration of the electronic control system will be described with reference to FIG. The output shaft of the engine 1 according to the present embodiment is provided with a transmission 150 that automatically switches the shift speed based on a shift characteristic that is set in advance according to an operation state.
Engine control device (ECU) 10 for controlling engine 1
0 and a transmission control unit (TCU) that controls the transmission 150 are connected to each other by two-way communication.

First, the ECU 100 for controlling the engine 1
Will be described. The ECU 100 mainly includes a main computer 101 as a central computer for engine control and a sub-computer 102 as a knock detection computer.
3. It is configured to include peripheral devices such as a drive circuit 104, A / D converters 105 and 123, an amplifier 121, and a frequency filter 122.

The main computer 101 has a CPU 10
5, ROM 106, RAM 107, backup RAM
This is a microcomputer in which a microcomputer 108, a counter / timer group 109, a serial communication interface SCI 112, and an I / O interface 110 are connected via a bus line 111. The sub computer 102 also has a CPU 114 and a ROM 1 similarly to the main computer 101.
15, a RAM 116, a counter / timer group 117, a serial communication interface SCI 119, and an I / O interface 118 connected via a bus line 120.
The SCIs 112 and 119 are connected to each other by serial communication lines.

When the ignition switch 96 is turned on, the constant voltage circuit 103
Of the main computer 101, the sub-computer 102, and the drive circuit 1
04 and the like so as to supply a predetermined constant voltage to peripheral devices. Further, the constant voltage circuit 103 is directly connected to the battery 95, supplies backup power to the backup RAM 108 of the main computer 101, and retains data. The ignition switch 96 is connected to an input port of the I / O interface 110 of the main computer 101, turns on the power supply relay 97, and turns on the battery 9
Power is supplied to each actuator from 5 through a second relay contact, and the fuel pump relay 98 is turned on to drive the fuel pump 31.

The main computer 101 has various sensors 80, 81, 83 to 88 other than the knock sensor 82 and the vehicle speed sensor 8 connected to the input port of the I / O interface 110.
9, ignition switch 96, starter switch 9
2 and the battery 95 are connected. The igniter 36 is connected to the output port of the I / O interface 110, and the ISCV 25, the injector 30, the switching solenoid valves 76, SOL. W, SO
L. 1-4, duty solenoid valve D. SOL. 1,
D. SOL. 2, and the relay coil of the fuel pump relay 98 are connected.

Then, the fuel pump 31 is driven by turning on the fuel pump relay 98 by the drive circuit 104, and the switching solenoid valves 76,
SOL. W, SOL. ON / OFF signals to the duty solenoid valves D.1 to D.4. SOL. 1, D. SOL. 2
To control the turbocharger operation number switching control and the supercharging pressure control, and output a drive pulse width signal corresponding to the calculated fuel injection amount to the injector 30 of the corresponding cylinder at a predetermined timing to obtain the fuel. Injection control is performed, an ignition signal is output to the igniter 36 at a predetermined timing to perform ignition timing control, and a control signal is output to the lSC valve 25 to execute idle speed control and the like.

The input port of the I / O interface 110 can be connected to a test mode switch 124 and a read memory switch 125 each of which is a connector. Therefore, by connecting the test mode switch 124 at the line end of the factory or at a dealer, the main computer 101 executes a predetermined test mode control to perform various inspections and inspections. Further, when the read memory switch 125 is connected, data of the main computer 101 is extracted to perform a failure diagnosis or the like.

The sub-computer 102 connects the crank angle sensor 87 to the input port of the I / O interface 118.
And a cam angle sensor 88, and a knock sensor 82 is connected via an amplifier 121 for amplifying a knock detection signal, a frequency filter 122 for extracting necessary frequency components, and an A / D converter 123 for converting into a digital signal. . Also I
An output port of the I / O interface 118 is connected to an input port of the I / O interface 110 of the main computer 101.

Then, when the ignition switch 96
When a constant voltage is supplied to the sub-computer 102 during engine operation by N, knock control is executed in all operating states to determine whether knock has occurred. Therefore, the occurrence of knock is determined, and the determination result is transmitted to the main computer 101.
Is entered in the main computer 101, the SCI 11
The knock data is read via the serial communication line of the igniter 36 and the ignition timing of the igniter 36 is retarded.

On the other hand, the TCU 20 for controlling the transmission 150
Reference numeral 0 denotes a power supply circuit, peripheral circuits, a microcomputer, and the like, similar to the ECU 100.
Via the SCI 112.

The transmission 150 is provided with a torque converter 152 having a lock-up clutch 151 for engaging the impeller and the turbine, various hydraulic clutches and various hydraulic brakes for switching between forward and reverse, and for shifting gears. An automatic transmission 153 provided with a clutch mechanism unit composed of a transmission mechanism and a main transmission mechanism unit composed of a planetary gear, etc., is connected to the automatic transmission 153. Various automatic transmissions 153 control line pressure and pilot pressure to each mechanism unit. A hydraulic control unit 154 integrally formed with a control valve is provided continuously.

The TCU 200 receives signals from a throttle opening sensor 85, a water temperature sensor 83, and a vehicle speed sensor 89 which are shared with the ECU 100, as well as a turbine speed signal, an ATF oil temperature signal, a brake signal, and a shift operation. For example, an operation position signal or the like from the selection mechanism unit 155 is input.

The TCU 200 determines the current shift range of the automatic transmission 153 based on the operation position signal of the select mechanism, and based on the shift characteristics (including output release, lock, and reverse rotation) stored in the TCU 200 in advance. According to the driving state based on the throttle opening detected by the throttle opening sensor 85 and the vehicle speed detected by the vehicle speed sensor 89, the gear ratio in the current shift range is controlled via the hydraulic control unit 154, and Up clutch 1
Control the fastening, slipping and releasing of 51, and at the same time, EC
The data of the current gear position is transmitted to U100.

In the above control system, in the turbocharger operation control by the ECU 100, the supercharging pressure control is performed in the single turbo state in which only the primary turbocharger 40 performs the supercharging operation at the time of the engine low speed range. When the engine is in the high engine speed range, the supercharging pressure control is performed in a twin turbo state in which the primary turbocharger 40 and the secondary turbocharger 50 are both supercharged.

In the supercharging pressure control in each turbo state,
First, a basic target supercharging pressure is set based on an engine operating state based on an engine speed and a throttle opening, and the basic supercharging pressure is corrected by various correction terms to set a target supercharging pressure. Then, control is performed so that the actual supercharging pressure follows the target supercharging pressure.

In this case, in the present engine 1 in which the transmission 150 that automatically switches the gear position based on the shift characteristics set in advance according to the operating state is continuously provided, the engine is operated in the driving range excluding the neutral range and the P range. When the accelerator pedal is depressed while the vehicle is stopped with the brakes applied, the automatic transmission 1
There is a possibility that an excessive load is applied to the brake band, the clutch and the like without the upshifting of the gear stage 53, and a problem may occur. In particular, if a stall to fully open the accelerator is performed while the vehicle is stopped with the brake depressed in the travel range, a supercharging pressure equivalent to that when the vehicle is fully opened is applied, and the transmission 150 including the automatic transmission 153 is driven by excessive driving force. There is a strong possibility that a failure will occur.

Accordingly, in a single turbo state in which the vehicle can be brought to a stopped state in which the brake is depressed in the travel range, one of the correction terms for correcting the basic target supercharging pressure is to reduce the basic target supercharging pressure in accordance with the gear ratio. A gear ratio correction coefficient for correction is introduced as a gear position correction coefficient, representing the gear ratio of the automatic transmission 153 as a gear position.

In the single turbo state, when the vehicle speed is lower than the set value and the vehicle can be considered to be in the stopped state, the basic target supercharging pressure is reduced and corrected by the gear position correction coefficient to set the target supercharging pressure. By controlling the actual supercharging pressure so as to converge to the target supercharging pressure, the target supercharging pressure is reduced and an excessive driving force is applied to the transmission 150 even when the accelerator is depressed while the brake is depressed while the travel range is maintained. Therefore, the occurrence of problems with the transmission 150 is prevented beforehand, and the durability and reliability of the transmission 150 are improved.

Here, the gear position correction coefficient is set so that the reduction correction amount with respect to the basic target supercharging pressure increases as the gear ratio increases. Further, when the vehicle is stopped by depressing the brake in the traveling range, the primary turbocharger 40 is in a single turbo state in which only the primary turbocharger 40 operates. Therefore, the correction using the gear position correction coefficient is performed only during the single turbo.
At the time of the twin turbo, the correction of the basic target supercharging pressure by the gear position correction coefficient is not performed.

That is, the ECU 100 realizes the functions of the basic target boost pressure setting means, the gear ratio correction coefficient setting means, and the target boost pressure setting means according to the present invention. 13 to 13 added to the supercharging pressure control routine of FIG.
The DUTY1 calculation routine in FIG. 17 and the D in FIGS.
The function of each means is realized by the UTY2 calculation routine.

Hereinafter, processing related to the supercharging pressure control of the primary turbocharger 40 and the secondary turbocharger 50 in the main computer 101 of the ECU 100 will be described with reference to the flowcharts of FIGS.

First, the operations of the primary turbocharger 40 and the secondary turbocharger 50 are controlled by the job shown in FIG. This job is roughly divided into a turbo switching control routine and a supercharging pressure control routine.
Of the turbo switching control routine and the supercharging pressure control routine of step S2 are executed at a set time of, for example, 10 ms, and set to a high priority job. The boost pressure control routine includes a DUTY1 for the boost pressure feedback control.
A calculation routine and a DUTY2 calculation routine are added.

The DUTY1 operation routine is a primary wastegate control duty solenoid valve D.D. in the primary wastegate control mode in which the opening degree of the primary wastegate valve 41 is changed and the supercharging pressure is feedback controlled. SOL. This is a routine for calculating the duty ratio DUTY1 of the control signal with respect to 1. In the exhaust control valve small opening control mode in which the opening degree of the exhaust control valve 53 is slightly opened and the supercharging pressure is feedback controlled, the DUTY2 calculation routine performs the exhaust control valve small opening control duty solenoid valve D. SOL. This is a routine for calculating the duty ratio DUTY2 of the control signal for the control signal No. 2.

Here, the DUTY1 operation cycle and the DUT
In the Y2 operation cycle, the exhaust control valve 53 is formed larger than the primary wastegate valve 41, and the primary wastegate valve 41 has a higher responsiveness than the exhaust control valve 53. DU in consideration of
The DUTY2 operation cycle is longer than the TY1 operation cycle. That is, it is set so that the DUTY1 calculation is performed, for example, every 160 ms, and the DUTY2 calculation is performed, for example, every 480 ms. In this way, the priority of all the routines is determined by the cycle time, the processing is performed based on this priority, and the low-order job is subjected to multiple waiting processing for the high-order job.

Therefore, first, the turbo switching control will be described with reference to the flowchart shown in the turbo switching control routine of FIGS. This turbo switching control routine is executed after the ignition switch 96 is turned on. Therefore, the ECU 1 is turned on by turning on the ignition switch 96.
When the power is turned on at 00, the system is initialized (each flag and each count value are cleared), and first, in step S10, the value of the twin turbo discrimination flag F1 is referred to. If the twin turbo discrimination flag F1 is cleared, the process proceeds to step S11, and if it is set, the process proceeds to step S60. The twin turbo discrimination flag F1 indicates that the current control state is the primary turbocharger 40
It is cleared in the single turbo state in which only the supercharging operation is performed, and is set in the twin turbo state in which both the turbochargers 40 and 50 are supercharged.

In the following description, the single turbo control will be described first, followed by the single-to-twin switching control and twin turbo control, and finally the twin-to-single switching control.

Immediately after the ignition switch 96 is turned on and when the current control state is a single turbo, F1
Since = 0, the process proceeds from step S10 to step S11. In step S11, the turbo switching determination value table is referred to with interpolation calculation based on the engine speed N, and the single to twin switching for determining the switching from the single turbo state to the twin turbo state at the standard atmospheric pressure (760 mmHg) is performed. The determination basic value Tp2B is set.

As shown in FIG. 22, the turbo switching determination value table stores the single turbo state to the twin turbo state based on the relationship between the engine speed N and the engine load (in this embodiment, the basic fuel injection pulse width) Tp. The single-to-twin switching determination line L2 for switching to the state and the twin-to-single switching determination line L1 for switching from the twin-turbo state to the single-turbo state are determined in advance by simulation or experiment under standard atmospheric pressure to obtain the single-turbo region. A twin turbo region is set. Then, corresponding to the respective lines L2 and L1, the single-to-twin switching determination basic value Tp2B and the twin->
The single switching determination basic value Tp1B is stored in advance at a series of addresses in the ROM 106 as a table using the engine speed N as a parameter.

Here, the single-to-twin switching determination line L2 is the point where the torque curve TQ1 for single turbo and the torque curve TQ2 for twin turbo match the output characteristics of FIG. 35 in order to prevent torque fluctuation at the time of switching. It is necessary to set to C, and therefore, as shown in FIG. 22, it is set to a low load side in accordance with an increase in the engine speed N from a high load in the low and middle speed ranges. Further, as shown in the figure, in order to prevent control hunting at the time of switching the number of turbochargers to be operated, the twin-to-single switching determination line L1 is shifted to the lower rotation speed side with respect to the single-to-twin switching determination line L2. It is set with a relatively wide width of hysteresis.

The turbo switching determination value table is given as a free grid table (unequally spaced grid table) using the engine speed N as a parameter. In a region where the respective switching determination basic values Tp2B and Tp1B greatly change with respect to the rotation speed N, the single-to-twin switching determination basic value Tp2B and the twin-to-single switching determination basic value Tp.
1B can be set more precisely. Thereby, the switching determination basic value Tp2 obtained by the interpolation calculation
B and Tp1B can be appropriately set in accordance with the engine speed N, so that the turbo switching timing can be optimized and controllability can be improved.

Next, the process proceeds to step S12, in which the single-> twin switching determination basic value Tp2B corresponding to the standard atmospheric pressure is corrected to decrease the basic value Tp2B as the atmospheric pressure ALT decreases.
Based on the atmospheric pressure (absolute pressure) ALT detected by the absolute pressure sensor 22, the twin atmospheric pressure correction coefficient KTWNALT is set by a linear function expression based on the atmospheric pressure ALT shown below. KTWNALT ← KALT1 × ALT + KALT0 (1) where KALT1 and KALT0 are constants

That is, the engine load (basic fuel) as a parameter when switching from the single turbo state in which only the primary turbocharger 40 is supercharged to the twin turbo state in which both the turbochargers 40 and 50 are supercharged. The injection pulse width) Tp depends on the intake air amount Q, and the intake air amount Q changes due to a difference in air density due to a change in the atmospheric pressure ALT. The relationship between the atmospheric pressure and the air density is apparent from the gas state equation. Thus, it is represented by a linear function equation in which the air density decreases as the atmospheric pressure ALT decreases.

For this reason, by comparing with the engine load (basic fuel injection pulse width) Tp, the single to twin switching determination basic value Tp2B corresponding to the standard atmospheric pressure which determines the switching from the single turbo state to the twin turbo state is reduced to the atmospheric pressure. Accordingly, the single-to-twin atmospheric pressure correction coefficient KTWNALT for correcting the decrease can be set by a linear function equation based on the atmospheric pressure ALT.

Therefore, the single to twin atmospheric pressure correction coefficient KTWNALT for correcting the single to twin switching determination basic value Tp2B corresponding to the standard atmospheric pressure by the atmospheric pressure is calculated by a simple linear function equation based on the atmospheric pressure ALT. A table that stores the single-to-twin atmospheric pressure correction coefficient KTWNALT using the atmospheric pressure ALT as a parameter, and interpolation calculation when setting the single-to-twin atmospheric pressure correction coefficient KTWNALT with reference to the table is completely unnecessary, so that memory is used. The capacity is reduced, and the setting process of the single to twin atmospheric pressure correction coefficient KTWNALT is simplified, and the single to twin atmospheric pressure correction coefficient KTW is reduced.
When setting the NALT, it is possible to significantly reduce the calculation load on the CPU 105 of the main computer 101 constituting the ECU 100.

When a single-to-twin atmospheric pressure correction coefficient KTWNALT is given by a table, the single-to-twin atmospheric pressure correction coefficient KTWNALT is set according to each atmospheric pressure ALT corresponding to the grid of the table.
The twin atmospheric pressure correction coefficient KTWNALT must be set. On the other hand, when the single-> twin atmospheric pressure correction coefficient KTWNALT is set by a linear function as in the present embodiment, the value given by the primary function is 2 Since only two constants KALT1 and KALT0 are determined, the setting can be performed very easily.

FIG. 23 shows the relationship between the atmospheric pressure ALT and the single to twin atmospheric pressure correction coefficient KTWNALT according to the above equation (1). As is apparent from FIG.
The constant KALT1 in the equation gives the slope of the single to twin atmospheric pressure correction coefficient KTWNALT, and the constant KALT0
Gives the intercept, and these constants KALT1, KA
LT2 is obtained in advance by calculating the optimum value by simulation or experiment, and is stored in the ROM 106 as fixed data.

Specifically, as shown in FIG. 23, in the present embodiment, each of the constants KALT1 and KALT0 is
When the atmospheric pressure ALT is the standard atmospheric pressure (760 mmHg),
The single-to-twin atmospheric pressure correction coefficient KTWNALT is set to KTWNALT = 1.0 corresponding to the state without correction, and the single-to-twin atmospheric pressure correction coefficient KTWNALT is reduced with a decrease in the atmospheric pressure ALT. For example, ALT = 400
At the time of mmHg, it is set to a value that gives KTWNALT = 0.75.

Then, by the processing from step S17 to be described later, the single to twin switching determination basic value Tp2B corresponding to the standard atmospheric pressure is changed to the single to twin atmospheric pressure correction coefficient KT.
Atmospheric pressure is corrected by WNALT to set a single-to-twin switching determination value Tp2. This single-to-twin switching determination value Tp2 is compared with a basic fuel injection pulse width Tp representing the engine load, and the basic fuel injection pulse width Tp is set. When the single-to-twin switching determination value Tp2 is exceeded, the process shifts to single-to-twin switching control for switching from the single turbo state to the twin turbo state.

Next, in steps S13 to S16, the single-to-twin atmospheric pressure correction coefficient KTWNALT is regulated to upper and lower limits. That is, when switching from the single turbo state to the twin turbo state by comparison with the engine load (basic fuel injection pulse width) Tp, the problem of the overspeed of the primary turbocharger 40 becomes a problem when the engine speed is lower than the standard atmospheric pressure. It is in the state of atmospheric pressure, and there is no problem in a region above the standard atmospheric pressure.

In a region above the standard atmospheric pressure,
The single to twin switching determination basic value Tp2B corresponding to the standard atmospheric pressure is corrected by using the single to twin atmospheric pressure correction coefficient KTWNALT calculated by the linear function of the above equation (1), and the single to twin switching determination value Tp2 is corrected.
Is compared with the basic fuel injection pulse width Tp representing the engine load, and when switching from the single turbo state to the twin turbo state is determined, the single turbo state is switched to the twin turbo state. Switching to is unnecessarily delayed.

For this reason, in the present embodiment, when the atmospheric pressure ALT is the standard atmospheric pressure (760 mmHg), the KTWNALT is set to KTWNALT = 1.0 corresponding to the state in which the single to twin atmospheric pressure correction coefficient KTWNALT is not corrected. In consideration of this, single to twin atmospheric pressure correction coefficient KTWN
The upper limit value for ALT is given as 1.0, and step S
At 13, the single-to-twin atmospheric pressure correction coefficient KTWNALT calculated by the above equation (1) is compared with 1.0 corresponding to the upper limit value. When KTWNALT> 1.0, the upper limit is set to KTWNALT in step S14 by setting the single to twin atmospheric pressure correction coefficient KTWNALT to 1.0 (KTWNLT).
(ALT ← 1.0), and proceeds to step S17.

In step S13, KTWN
If ALT ≦ 1.0, the process proceeds to step S15, where the single → twin atmospheric pressure correction coefficient KTWNALT is compared with a lower limit value TWNALTMIN. That is, the above (1)
Since the single-to-twin atmospheric pressure correction coefficient KTWNALT calculated by the linear function of the equation is set to decrease with the decrease of the atmospheric pressure ALT, the linear function of the equation (1) is obtained in a low atmospheric pressure state below a predetermined atmospheric pressure. Using the single to twin atmospheric pressure correction coefficient KTWNALT calculated by the equation as it is, the single to twin switching determination basic value Tp2B corresponding to the standard atmospheric pressure is corrected and the single to twin switching determination value Tp
When 2 is set, over-correction is performed, and this single-to-twin switching determination value Tp2 is compared with the basic fuel injection pulse width Tp representing the engine load to determine the switching from the single turbo state to the twin turbo state. Switching from the single turbo state to the twin turbo state is unnecessarily advanced.

Therefore, in step S15, the single to twin atmospheric pressure correction coefficient KTWNALT is set to the lower limit value TWNAL.
Compared to TMIN, KTWNALT <KTWNALTM
In the case of IN, the process proceeds to step S16, in which the single to twin atmospheric pressure correction coefficient KTWNALT is reduced to the lower limit value TWNAL.
Lower limit is regulated by TMIN (KTWNALT ← KTW
NALTMIN), and proceeds to step S17. Note that in the present embodiment, the lower limit value TWNALTMIN is
For example, as shown in FIG.
It is set to 0.75, which corresponds to 0 mmHg.

In step S15, KTWN
When ALT ≧ KTWNALTMIN, single →
Since the twin atmospheric pressure correction coefficient KTWNALT falls between the upper limit value 1.0 and the lower limit value TWNALTMIN (KTWNALTMIN ≦ KTWNALT ≦ 1.0),
Proceed directly to step S17.

Then, in step S17, the single-to-twin switching determination basic value Tp2B corresponding to the standard atmospheric pressure is corrected by the single-to-twin atmospheric pressure correction coefficient KTWNALT, and is compared with the basic fuel injection pulse width Tp representing the engine load. After setting the single to twin switching determination value Tp2 that determines the switching from the single turbo state to the twin turbo state, in step S18, the single to twin switching determination value Tp2 is compared with the current basic fuel injection pulse width Tp (engine load). , Tp <Tp2, step S
After 19, perform single turbo control and set Tp ≧ T
In the case of p2, the flow branches to step S30 to shift to single-to-twin switching control for switching from the single turbo state to the twin turbo state.

The single-twin switching determination value Tp2 is corrected to a smaller value as the atmospheric pressure ALT is lower by the single-twin atmospheric pressure correction coefficient KTWNALT. Therefore, as the atmospheric pressure ALT becomes lower, the primary turbocharger 40 based on the single-to-twin switching determination value Tp2 is used.
A single-to-twin switching determination line L2 for determining switching from the single turbo state with only the supercharging operation to the twin turbo state with the supercharging operation of both turbochargers 40 and 50,
As compared with the case of the standard atmospheric pressure indicated by the solid line in FIG.

As a result, the timing at which the engine operation region shifts from the single turbo region to the twin turbo region with the single-twin switching determination line L2 as a boundary is advanced, and the shift from the single turbo state to the single-twin switching control is made. The switching from the single turbo state to the twin turbo state is advanced earlier.

That is, when the supercharging pressure control is performed based on the absolute pressure, the supercharging pressure control may be performed at a high altitude such as traveling at high altitude where the atmospheric pressure ALT is low.
The lower the is, the greater the differential pressure between the target boost pressure and atmospheric pressure,
In order to obtain a predetermined target supercharging pressure, the rotation speed of the turbocharger becomes relatively high. As a result, the rate of increase in the number of revolutions of the primary turbocharger 40 with an increase in the engine speed N and the load Tp representing the engine operating state also increases. In the single turbo state in which only the primary turbocharger 40 is in the supercharging operation, most of the exhaust gas is introduced into the primary turbocharger 40. Therefore, the lower the atmospheric pressure ALT, the more the primary turbocharger 40 rotates. The engine operation range in which the state is set is expanded to the low load and low rotation side. As described above, this is remarkable when the primary turbocharger 40 has a low-speed small capacity.

Therefore, as the atmospheric pressure ALT becomes lower, the timing of shifting from the single turbo state based on the engine operating state to the single-to-twin switching control is advanced, and the exhaust control valve 53 which will be described later is fully opened, so that the exhaust control valve 53 is advanced. The exhaust flow introduced into the primary turbocharger 40 by fully opening the 53 is dispersed to the secondary turbocharger 50 to prevent the primary turbocharger 40 from over-rotating.

Thus, the primary turbocharger 40
As a result, the occurrence of surging due to an over-rotation state caused by an increase in the exhaust pressure and the exhaust flow rate and reaching the critical rotational speed is prevented regardless of a change in the atmospheric pressure ALT, and damage is prevented. Further, even in the same engine operation state, the rotation speed increase rate of the primary turbocharger 40 changes under the single turbo state due to the atmospheric pressure fluctuation, and the operation feeling due to the start of the operation of the secondary turbocharger 50 changes.
The lower the atmospheric pressure ALT is, the earlier the switching to the twin turbo state is made, so that the driving feeling accompanying the start of the operation of the secondary turbocharger 50 is substantially the same regardless of the atmospheric pressure change (for example, traveling at high altitude and traveling at low altitude). be able to.

Next, in step S18, Tp <Tp
2 and the single turbo control when the process proceeds from step 18 to step S19 will be described.

In the single turbo control, first, in step S
Switching solenoid valve SO for boost pressure and boost pressure relief valve at 19
L. 1 is turned off, and in step S20, the switching solenoid valve SOL. 2 is turned OFF. Next, the routine proceeds to step S21, where the value of the supercharging pressure control mode determination flag F2 is referred to. This supercharging pressure control mode determination flag F2 is set when the current operation area is in the exhaust control valve small opening control mode in which the supercharging pressure is controlled by the small opening of the exhaust control valve 53 and the secondary turbocharger 50 is preliminarily rotated. Is cleared when not in this mode.

Therefore, when the ignition switch 96 is
Immediately after N, the initial setting is performed, and when the operation area is outside the exhaust control valve small opening control mode area at the time of the previous execution of the routine, the process proceeds to step S22 because F2 = 0, and the first exhaust control valve switching solenoid is operated. Valve SOL. 3 is turned off, and in step S24, the second exhaust control valve switching solenoid valve SOL. 4 is turned off, and then step S25 is performed.
In steps S27 to S27, the twin turbo discrimination flag F1, the differential pressure search flag F3 described later, and the control valve switching time count value C1 are cleared, and the routine exits.

Therefore, in the low-rotation, low-load operation region outside the exhaust control valve small opening control mode region under the single turbo state, each switching solenoid valve SOL. 1 to 4 are all turned off. Therefore, the boost pressure relief valve 57 is provided with a boost pressure relief valve switching solenoid valve SOL. 1, the negative pressure from the surge tank 60 is introduced into the pressure chamber to open the valve against the urging force of the spring, and the intake control valve 55 is switched to the intake control valve switching solenoid valve SOL. 2 O
When a negative pressure is introduced into the pressure chamber of the actuator 56 by the FF, the valve is closed against the urging force of the swing. Further, the exhaust control valve 53 is provided with a switching solenoid valve SOL. When the atmospheric pressure is introduced into both chambers 54a and 54b of the exhaust control valve actuating actuator 54 by turning off the valves 3 and 4, the valve is closed by the urging force of the spring.

Then, by closing the exhaust control valve 53, the introduction of exhaust gas to the secondary turbocharger 50 is shut off.
The secondary turbocharger 50 is deactivated, and a single turbo state in which only the primary turbocharger 40 is activated. In addition, the closing of the intake control valve 55 prevents the supercharging pressure from the primary turbocharger 40 from leaking to the secondary turbocharger 50 via the intake control valve 55, and reduces the supercharging pressure. Is prevented.

Here, when the engine is in the single turbo state and is out of the exhaust control valve small-opening control mode region, or in the twin turbo state, the boost pressure feedback control is performed by the primary wastegate valve 41 as described later. This is done using only The supercharging pressure control uses the absolute pressure, sets a target supercharging pressure based on the engine operating state, compares the target supercharging pressure with the intake pipe pressure detected by the absolute pressure sensor 81, that is, the actual supercharging pressure P. According to the result, the primary wastegate control duty solenoid valve is controlled by proportional integral control (PI control). SOL. 1 and calculates the ON duty (duty ratio DUTY1) corresponding to the duty signal of the primary wastegate control duty solenoid valve D.1. SOL. 1 to control the primary wastegate valve 41.

On the other hand, if it is determined in step S21 that the current operation area is in the exhaust control valve small opening control mode and the supercharging pressure control mode determination flag F2 is set, the process proceeds to step S23, where the first exhaust is performed. Switching solenoid valve for control valve S
OL. 3 is turned on, and then the above-described steps S24 to S27 are performed.
Exit the routine via. Therefore, the first exhaust control valve switching solenoid valve SOL. 3 is turned ON, a positive pressure is introduced into the positive pressure chamber 54a of the exhaust control valve actuating actuator 54, and the exhaust control valve small opening control duty solenoid valve D.D. SOL. The positive pressure is regulated by the duty control of 2, and the exhaust control valve 53 is opened slightly. Therefore, the exhaust control valve 5
Part of the exhaust is secondary turbocharger 5 due to small opening of 3
0, and the secondary turbocharger 50 is pre-rotated to prepare for the transition to the twin turbo.

In this state, since the intake control valve 55 is closed, the supercharging pressure between the downstream of the compressor 50b of the secondary turbocharger 50 and the intake control valve 55 (the secondary turbocharger 50 At this time, the supercharging pressure is leaked by opening the supercharging pressure relief valve 57, thereby smoothing the preliminary rotation.

As described above, in the single turbo state, most of the exhaust gas from the engine 1 is introduced into the primary turbocharger 40, and the compressor 40b is rotationally driven by the turbine 40a. So compressor 40b
The compressed air is cooled by the intercooler 20, the flow rate is adjusted by the opening degree of the throttle valve 21, and supplied to each cylinder at a high filling rate through the chamber 22 and the intake manifold 23 to be supercharged. Works. And
In the single turbo state in which only the primary turbocharger 40 operates, as shown in the output characteristics of FIG. 35, a torque curve TQ1 at the time of a single turbo with a high shaft torque in the low and middle rotation speed ranges is obtained.

Next, the single to twin switching control will be described. In step S18 described above, Tp ≧ Tp2, that is, the current operation region is the single-to-twin switching determination line L
If it is determined that the transition from the single turbo region to the twin turbo region (see FIG. 22) has been made at the boundary of Step 2, the process branches from Step S18 to Step S30, and from the single turbo state in which only the primary turbocharger 40 operates, to both turbochargers. The single-to-twin switching control for switching to the twin turbo state in which the feeders 40 and 50 are operated is executed.

Then, first, at step S30, the switching solenoid valve SOL. 1 is determined, and at step S32, the first exhaust control valve switching solenoid valve SOL. 3 is determined, and both switching solenoid valves SOL. When both 1 and 3 are ON,
Proceed directly to step S34. Further, each switching solenoid valve SOL. If 1, 3 is OFF, step S31,
After each is turned ON in S33, the process proceeds to step S34.

Therefore, the boost pressure relief valve 57 is provided with a boost pressure relief valve switching solenoid valve SOL. When 1 is turned on, the positive pressure from the positive pressure passage 64a is introduced into the pressure chamber, and the valve is immediately closed by this positive pressure and the urging force of the spring as shown in FIG. The exhaust control valve 53 includes a first exhaust control valve switching solenoid valve SOL. The valve is opened by introducing a positive pressure into the positive pressure chamber 54a of the exhaust control valve actuating actuator 54 at 0N.

When the mode is changed from the small exhaust control valve open control mode under the single turbo state to the single-to-twin switching control, the exhaust control valve small open control duty solenoid valve D.C. SOL. 2 is fully closed, and the positive pressure through the positive pressure passage 64b is applied to the exhaust control valve small opening control duty solenoid valve D.
SOL. 2, the gas is directly introduced into the positive pressure chamber 54a of the exhaust control valve actuating actuator 54 without being leaked, so that the opening of the exhaust control valve 53 is increased.

The relief passage 58 is shut off by closing the supercharging pressure relief valve 57, and the rotational speed of the secondary turbocharger 50 is increased by opening the exhaust control valve 53 and increasing its opening. At the same time, the supercharging pressure between the downstream of the compressor 50b of the secondary turbocharger 50 and the intake control valve 55 is gradually increased to prepare for the transition to the twin turbo state.

In step S34, the differential pressure search flag F3
If F3 = 0, the process proceeds to step S35, and if F3 = 1, the process jumps to step S39.
After the shift to the single-to-twin changeover control, the process proceeds to step S35 because F3 = 0 when the first routine is executed. First, the exhaust control valve opening delay time setting table is referenced with interpolation calculation based on the vehicle speed VSP, and the single-to-single- → Fully-open control of the exhaust control valve 53 after the transition to the twin switching control (the second exhaust control valve switching solenoid valve SOL. 4 is turned on from OFF.
The exhaust control valve opening delay time T1 that determines the timing is set.

Further, in step S36, by referring to the intake control valve opening delay time setting table with interpolation calculation based on the vehicle speed VSP, after the exhaust control valve 53 is fully opened, the opening control of the intake control valve 55 (for the intake control valve). Switching solenoid valve SO
L. 2 is changed from OFF to ON). The intake control valve opening delay time T2 for determining the condition of the start timing is set. Then, in step S37, the differential pressure (read value of the differential pressure sensor 80) DP between the upstream pressure PU and the downstream pressure PD of the intake control valve 55
Based on S (= PU−PD), the intake control valve opening differential pressure DPSST for determining the valve opening control start timing of the intake control valve 55
Set.

FIG. 25 is a conceptual diagram of an exhaust control valve opening delay time setting table, and FIG. 26 is a conceptual diagram of an intake control valve opening delay time setting table. As shown in the figure, as the vehicle speed VSP increases, the exhaust control valve opening delay time T1 and the intake control valve opening delay time T2 are shortened, and the timing of fully opening the exhaust control valve 53 and the timing of opening the intake control valve 55, ie, The timing to switch to the twin turbo state is advanced, the acceleration response is uniform regardless of the vehicle speed, and the drivability is improved.

Also, by giving each of the delay times T1 and T2 as a condition for switching from the single turbo state to the twin turbo state, the engine speed can be changed by shifting the transmission (upshift) or temporarily blowing the engine. Unnecessary switching of the supercharger from the single turbo state to the twin turbo state due to the temporary increase of N is prevented beforehand.

In other words, each delay time T1, T
2 is set according to the set vehicle speed for each gear position that determines the shift (upshift), and the vehicle speed V = 0 Km / h
It may be set as a temporary air blowing countermeasure at the time, so the exhaust control valve opening delay time setting table,
And an intake control valve opening delay time setting table is provided as a free grid table (unequally spaced grid table), and the respective delay times T1 and T2 are set for each corresponding vehicle speed. It can be simplified.

FIG. 27 is a conceptual diagram of an intake control valve opening differential pressure setting table. As shown in the figure, the differential pressure DPS immediately after the engine operating state shifts from the single turbo region to the twin turbo region (see FIG. 22) with the single-to-twin switching determination line L2 (single-to-twin switching determination value Tp2) as a boundary. Is more negative, that is, the downstream pressure PD is higher than the upstream pressure PU of the intake control valve 55, and the higher the supercharged state, the more the intake control valve opening differential pressure DPSST is set to the negative side, and the intake control valve 55 is opened. Advance the timing,
Improve acceleration response.

After setting the delay times T1 and T2 and the intake control valve opening differential pressure DPSST, step S is executed.
The program proceeds to S38, in which a differential pressure search flag F3 is set, and the program proceeds to step S39. In step S39, the second exhaust control valve switching solenoid valve SOL. 4 to determine whether the exhaust control valve 53 has already been fully opened. 4 = ON, and if the exhaust control valve fully open control has already been started, the process jumps to step S49 to jump to the second exhaust control valve switching solenoid valve SOL. 4 is kept ON, and SOL. 4 = OFF
In this case, since the exhaust control valve fully open control has not been executed, the process proceeds to step S40, and the control valve switching time count value C1 is compared with the exhaust control valve open delay time T1.

Then, at step 40, C1 ≧ T1
If the exhaust control valve 53 is not fully opened and the exhaust control valve opening delay time T1 has elapsed after the transition from the single to the twin switching control, the process jumps to step S47 to jump to the second exhaust control valve switching solenoid valve. SOL. Turn 4 ON
The exhaust control valve 53 is fully opened as shown in FIG. Also, C
If the delay time before 1 <T1 has elapsed, step S4
In step S17, the engine load Tp is compared with a value obtained by subtracting the set value WGS from the single-to-twin switching determination value Tp2 previously set in step S17, and Tp <Tp2-WGS.
In this case, the process returns to step S19, in which the single-to-twin switching control is stopped, and the state is immediately switched to the single turbo state. This is to eliminate the uncomfortable feeling of driving by returning to the single turbo state when the engine load Tp decreases.

More specifically, as shown in FIG.
The engine operating state changes from single turbo range to single →
Once the line crosses the twin switching determination line L2 (Tp2) to the twin turbo region side, the delay is maintained unless the vehicle crosses the twin → single switching determination line L1 (twin → single switching determination value Tp1, details will be described later) to the single turbo region side. After the lapse of the time T1, the exhaust control valve 53 is fully opened (step S47). Further, when the differential pressure DPS reaches the intake control valve opening differential pressure DPSST after the delay time T2, the intake control valve 55 is opened (step S52), and the twin turbo Switch to state.

Therefore, once the operation state remains in the region surrounded by the twin-to-single switch determination line L1 and the single-to-twin switch determination line L2 after the vehicle has once passed the single-to-twin switch determination line L2, It switches to the twin turbo state after a lapse of time. However, in this region, as shown by the point B in FIG. 35, the shaft torque at the time of the twin turbo by the operation of the secondary turbocharger 50 is rather lower than the shaft torque at the time of the single turbo. Switching to the state causes a torque shock due to a sudden decrease in torque, and gives the driver an uncomfortable feeling.

In order to cope with this, the twin-to-single switching judgment line L1 is changed to the single-to-twin switching judgment line L1.
2, the width (hysteresis) of both switching determination lines may be reduced, but if the width between both switching determination lines L1 and L2 is reduced, the frequency of switching between the single turbo and the twin turbo increases, and each control valve When the negative pressure capacity of the surge tank 60 as the negative pressure source for operating the surge tank 60 is insufficient, the surge tank 60 must have a large capacity, and if the width of both the switching determination lines is too narrow, the operating state becomes single → When the engine stays near the twin switching determination line L2, there is a disadvantage that the boost pressure relief valve 57 without the setting of the switching delay time causes chattering due to the fluctuation of the engine load Tp which is a parameter of turbo switching.

In order to prevent these, the operating condition is changed from single to
After exceeding the twin switching determination line L2 to the twin turbo region side and before the delay time T1 elapses, the set value WGS is subtracted from the single-to-twin switching determination line L2 to the single turbo region side with a small interval, as shown in FIG. The single-to-twin switching determination stop line L3 (Tp2-
(WGS) exceeds the single turbo range, the single-to-twin switching control for switching to the twin turbo state is stopped, the state is immediately shifted to the single turbo state, and the single turbo state in which only the primary turbocharger 40 operates is maintained. This eliminates the operation at the low shaft torque at point B in FIG. 35 and improves the operability while maintaining the high shaft torque at point A.

On the other hand, in step S41, Tp ≧ Tp2-W
If it is determined by GS that the engine load Tp has not decreased, the process proceeds to step S42, and based on the engine speed N, the switching determination value table is referred to with interpolation calculation to set a primary turbo overspeed determination basic value EM2Tp. The primary turbo overspeed determination basic value EM2Tp is a primary turbo overspeed region in which the engine operation region is in a single turbo state due to a sudden increase in the engine speed N and the engine load Tp before the delay time T1 elapses after the shift from the single to the twin switching control. And a reference value for judging whether or not the state has shifted to the primary turbo supercharging under the single turbo state, as shown in FIGS. 22 and 30 from the relationship between the engine speed N at the standard atmospheric pressure and the engine load Tp. Machine 4
A primary turbo overspeed determination line L4, which is a boundary of a primary turbo overspeed region (shown by oblique lines in FIG. 29) at which the critical speed reaches 0, is determined in advance by simulation or experiment, and the primary turbo overspeed determination at this standard atmospheric pressure is performed. In response to the line L4, the ROM 10
6 is stored as a switching determination value table using the engine speed N as a parameter at a series of addresses. The primary turbo overspeed determination line L4 is naturally set to a higher load side than the single-to-twin switching determination line L2.

The switching determination value table is given as a free grid table (unequally spaced grid table) using the engine speed N as a parameter. In a region where the primary turbo overspeed determination basic value EM2Tp greatly changes with respect to the number N, the primary turbo overspeed determination basic value EM2Tp can be set more precisely.

As a result, the primary turbo overspeed determination basic value EM2Tp obtained by the interpolation calculation can be appropriately set in accordance with the engine speed N.
A primary turbo overspeed determination value EMV2 set by correcting a primary turbo overspeed determination basic value EM2Tp by a determination value atmospheric pressure correction coefficient KEM2 by a process described below.
By comparing Tp with the basic fuel injection pulse width Tp representing the engine load, the primary turbo overspeed region can be accurately determined. When the engine operation region is in the primary turbo overspeed region, the exhaust control is immediately performed. By fully opening the valve 53 and allowing exhaust gas to flow also to the secondary turbocharger 50, the exhaust flow rate to the primary turbocharger 40 can be reduced, and the overspeed of the primary turbocharger 40 can be accurately prevented. , Reliability can be improved.

Next, at step S43, the atmospheric pressure ALT
Then, the determination value atmospheric pressure correction coefficient KEM2 is set by referring to the determination value atmospheric pressure correction coefficient table with the interpolation calculation based on.
FIG. 28 shows a conceptual diagram of the determination value atmospheric pressure correction coefficient table. As shown in the figure, the determination value atmospheric pressure correction coefficient KEM2
Is 1.0 at or above the standard atmospheric pressure (760 mmHg).
It is set to a smaller value as the atmospheric pressure becomes lower.

In step S44, the primary turbo overspeed determination value E is obtained by multiplying the primary turbo overspeed determination basic value EM2Tp by the determination value atmospheric pressure correction coefficient KEM2.
MV2Tp is calculated. As a result, as shown in FIG. 30, the primary turbo overspeed determination value EMV2Tp is also corrected for the atmospheric pressure, and as the atmospheric pressure ALT decreases, the primary turbo overspeed determination line L4 based on the primary turbo overspeed determination value EMV2Tp is changed to FIG. As compared with the case of the standard atmospheric pressure indicated by the solid line, the load is corrected to the low-load and low-rotation side similarly to the single-to-twin switching determination line L2 indicated by the dashed line. As a result, the primary turbo overspeed determination line L4 is set to a higher load side than the single to twin switching determination line L2 regardless of the atmospheric pressure change, and at the time of the single to twin switching, the primary turbo overspeed determination line L4 is set to a higher load side than this line L4. A rotation area is set.

Next, at step S45, the engine load T
p is compared with the primary turbo overspeed determination value EMV2Tp, and if it is determined that there is no risk of primary turbo overspeed due to Tp <EMV2Tp, the process branches to step S46 to count up the control valve switching time count value C1, Exit the routine. On the other hand, after the transition from the single to twin switching determination line L2 to the twin turbo range and before the set time T1 has elapsed, the engine load Tp becomes Tp ≧ E.
If it is determined that the value has increased to MV2Tp and has exceeded the primary turbo overspeed determination line L4, step S45 is performed.
Then, the process proceeds to step S47.

In step S47, the second exhaust control valve switching solenoid valve SOL. 4 is immediately turned on, and the exhaust control valve 53 is fully opened as shown by the broken line in FIG. Along with this, the opening timing of the intake control valve 55 is advanced, and the air conditioner shifts quickly to the twin turbo region, and the rapidly increasing exhaust gas also flows to the secondary turbocharger 50 side to reduce the load on the primary turbocharger 40. I do. As a result, a large amount of exhaust is prevented from flowing to only the primary turbocharger 40 and over-rotating, so that surging and damage do not occur.
At the same time, switching to the twin turbo range is quickly performed in accordance with the driver's intention to accelerate.

At this time, as described above, the atmospheric pressure AL
The engine operating region in which the primary turbocharger 40 is over-rotated as the T is lower is expanded to a low load and low rotation side. In order to determine the over-rotation of the primary turbocharger 40 in response to this, The primary turbo overspeed determination line L4 is corrected to the low load and low speed side with the decrease in the atmospheric pressure ALT, so that the primary turbo overspeed can be accurately determined even if the atmospheric pressure ALT changes, and It is possible to appropriately and reliably prevent overspeed of the primary turbocharger 40 irrespective of a change in atmospheric pressure and prevent damage.

Further, a primary turbo overspeed determination basic value EM2Tp is set based on the engine speed N, and the primary turbo overspeed determination value EMV2Tp obtained by correcting the atmospheric pressure with the determination value atmospheric pressure correction coefficient KEM2 and the engine load. Tp and the primary turbocharger 40
Since the transition to the overspeed state is determined, the determination can be made accurately over the entire range of the engine speed, the engine load, and the atmospheric pressure, and the primary turbocharger 40 can be reliably prevented from being damaged.

After the shift to the single-to-twin switching control, the control valve switching time count value C1 reaches the exhaust control valve opening delay time T1, and when C1 ≧ T1, the process jumps from step S40 to step S47, and the second exhaust control is performed. Valve switching solenoid valve SOL. When the exhaust control valve 53 is fully opened by turning ON the control valve 4, the process proceeds to step S48, where the control valve switching time count value C1 is cleared in order to measure the time after the exhaust control valve is fully opened, and the process proceeds to step S49. .

When the process proceeds from step S39 or step S48 to step S49, the count value C1 representing the time after the exhaust control valve fully opening control (SOL.4 OFF → ON) is compared with the intake control valve opening delay time T2. However, if C1 <T2, it is determined that the intake control valve opening condition is not satisfied, and the count value C1 is determined in step S46.
Count up and exit the routine. Also, C1 ≧ T
In the case of 2, it is determined that the valve opening condition is satisfied, and step S50 is performed.
To the current differential pressure DPS and the intake control valve opening differential pressure DPSS
T is compared to determine whether it has reached the valve opening start timing of the intake control valve 55.

When DPS <DPSST, it is determined that the valve opening start timing has not been reached, and the routine proceeds to step S51. When DPS ≧ DPSST, the upstream pressure PU and the downstream pressure PD of the intake control valve 55 are substantially equal to each other. The compressor 5 of the secondary turbocharger 50
0b and the intake pressure control valve 55, the boost pressure of the secondary turbocharger 50 increases and the primary turbocharger 4
0, it is determined that the intake control valve opening start timing has been reached, and the routine proceeds to step S52, where the intake control valve switching solenoid valve SOL. 2 is turned on, and FIG.
The intake control valve 55 is opened as shown in FIG.

As a result, supercharging from the secondary turbocharger 50 is started, and a twin turbo state is established. Then, the process proceeds to step S53, and upon completion of the single-to-twin switching control, the twin-turbo discrimination flag F1 is set for the next transition to the twin-turbo control, and the routine exits.

In step S50, DPS <DPSS
If it is determined that the time is T and the process proceeds to step S51, the count value C1 is further compared with a value obtained by adding a set value TDP to the intake control valve opening delay time T2, and C1 <T2 + TD.
When P, the count value C1 is counted up in step S46 and the routine is exited. When C1 ≧ T2 + TDP, the process proceeds to step S52, and even if the differential pressure DPS does not reach the intake control valve opening differential pressure DPSST, switching for the intake control valve is performed. Solenoid valve SOL. 2 is turned on, the intake control valve 55 is opened, and a transition is made to the twin turbo state.

That is, the second exhaust control valve switching solenoid valve SOL. 4 is turned on and the exhaust control valve 53 is fully opened, the rotation speed of the secondary turbocharger 50 is further increased, and the compressor pressure (supercharging) by the secondary turbocharger 50 between the compressor 50b and the intake control valve 55 33), the differential pressure DPS between the upstream and downstream of the intake control valve 55 increases as shown in FIG.
When the detection value of the differential pressure DPS detected by the differential pressure sensor 80 does not increase due to the failure of the system 0, after the exhaust control valve 53 is fully opened,
By any time, the intake control valve 55 is not opened, the supercharging pressure between the compressor 50b of the secondary turbocharger 50 and the intake control valve 55 rises abnormally, and the secondary turbocharger 50 generates surging. Damage. For this reason, even after the exhaust control valve 53 is fully opened, even if the differential pressure DPS does not reach the intake control valve opening differential pressure DPSST, T2 + TDP
By opening the intake control valve 55 after the elapse of the set time given by, damage to the secondary turbocharger 50 due to failure of the differential pressure sensor 80 system is prevented.

The state of switching from the single turbo state to the twin turbo state by the above single-to-twin switching control is shown in the time chart of FIG.

As described above, in the single-to-twin switching control, first, the supercharging pressure relief valve 57 is closed, the exhaust control valve 53 is opened, and the preliminary rotation speed of the secondary turbocharger 50 is reduced. After that, the exhaust control valve opening delay time T1 gives a time necessary for increasing the preliminary rotation speed of the secondary turbocharger 50, and after the delay time T1, the exhaust control valve 53 is fully opened.

Then, the supercharging pressure by the secondary turbocharger 50 between the compressor 50b of the secondary turbocharger 50 and the intake control valve 55 rises, and the differential pressure DPS rises. The operation delay time until the exhaust control valve 53 is fully opened is compensated by the control valve opening delay time T2, and after the delay time T2 elapses, the intake control valve 5
5 is the intake control valve opening differential pressure DP.
When the SST is reached, the intake control valve 55 is opened.

Thus, the primary turbocharger 4
From single turbo operation with only 0 operating to dual turbocharger 4
Switching to the twin turbo state by the 0,50 operation is performed smoothly, and the upstream pressure PU of the intake control valve 55 is further increased.
At the point when the pressure and the downstream pressure PD become substantially equal, the intake control valve 55
And the supercharging from the secondary turbocharger 50 is started, so that the occurrence of torque shock due to a temporary decrease in the supercharging pressure that occurs when switching to the twin turbo state is effectively and reliably prevented. .

After the shift from single to twin switching control, even if the set time (exhaust control valve opening delay time T1) has not been reached, Tp ≧ EMV2Tp (step S45).
When it is determined that the engine operation region has shifted to the primary turbo overspeed region under the single turbo state, as shown by the broken line in FIG. 33, the second exhaust control valve switching solenoid valve SOL. 4 to ON to fully open the exhaust control valve 53 and disperse the exhaust gas to the secondary turbocharger 50 side, so that the primary turbocharger 40 is in an overspeed state due to a rapid increase in the exhaust pressure and the exhaust gas flow rate, and reaches the critical speed. Thus, damage to the primary turbocharger 40 due to the occurrence of surging is reliably prevented.

Further, in the primary turbo overspeed region, that is, when the engine is under the high load and high speed condition, the start timing of the fully opening of the exhaust control valve 53 is advanced, and accordingly, as shown by the broken line in FIG. The opening timing of the control valve 55 is also advanced, and the state is quickly switched to the twin turbo state. For this reason, as shown in the output characteristic diagram of FIG. 35, it is possible to quickly switch from the single turbo state to the twin turbo state in which the shaft torque is high in the region on the high rotation side bordering on the single-to-twin switching determination line L2. At the same time, good acceleration performance can be obtained by adapting to the driver's acceleration requirements.

Next, the twin turbo control will be described. If the twin-turbo discrimination flag F1 is set by the end of the single-to-twin switching control, or if the twin-turbo state has been set at the time of the previous execution of the routine, the flow branches from step S10 to step S60 according to F1 = 1 when the current routine is executed.

Then, in step S60, based on the engine speed N, the turbo switching decision value table is referred to with interpolation calculation to set the twin-single switching decision basic value Tp1B (see FIG. 22). Next, the process proceeds to step S61,
Twin → Based on atmospheric pressure (absolute pressure) ALT → Refer to single atmospheric pressure correction coefficient table with interpolation calculation, Twin →
The single atmospheric pressure correction coefficient KSGLALT is set. This twin → single atmospheric pressure correction coefficient KSGLALT is
As shown in FIG. 31, similarly to the single-to-twin atmospheric pressure correction coefficient KTWNALT, the twin-to-single switching determination line L1 is set to have a low load and a low load by setting the standard atmospheric pressure or higher to 1.0 and setting it to be smaller as the atmospheric pressure is lower. Correct to the rotation side.

Thereafter, in step S62, the basic value Tp1B for judging twin-single switching is multiplied by the twin-single atmospheric pressure correction coefficient KSGLALT, and the basic value Tp1B for judging twin-single switching is corrected by the twin-single atmospheric pressure correction coefficient KSGLALT. , A twin-to-single switching determination value Tp1 for determining switching from the twin turbo state to the single turbo state is set.

As a result, the twin-to-single switching determination line L1 for determining the switching from the operation of both the turbochargers 40 and 50 to the operation of the primary turbocharger 40 alone is also the atmospheric pressure as shown by the dashed line in FIG. Corrected, it is possible to set a substantially constant appropriate hysteresis regardless of the change in the atmospheric pressure, and it is possible to make the operation feeling accompanying the switching of the secondary turbocharger inoperative regardless of the change in the atmospheric pressure substantially the same .

Then, the program proceeds to a step S63, wherein the engine load Tp is compared with the twin-to-single switching determination value Tp1. If Tp> Tp1, the current operating state is in the twin turbo range and the determination value search flag is set at the step S64. F
4 is cleared, the single turbo region duration time count value C2 for counting the elapsed time after shifting to the single turbo region is cleared in step S65, and then the process jumps to step S74, where the process proceeds from step S74 to step S74.
77, the switching solenoid valve SOL.
1, the switching solenoid valve SOL. 2, 1st
Second exhaust control valve switching solenoid valve SOL. 3 and 4 are respectively turned on, the supercharging pressure relief valve 57 is closed, the intake control valve 55 is opened, and the exhaust control valve 53 is fully opened. In step S78, the twin turbo discrimination flag F1 is set. Returning to step S27, after clearing the control valve switching time count value C1, the process exits the routine.

In the twin turbo state, by closing the supercharging pressure relief valve 57, opening the intake control valve 55, and fully opening the exhaust control valve 53, the secondary turbocharger is added to the primary turbocharger 40. The full-scale operation of the turbocharger 50 results in a twin turbo state due to the operation of the turbochargers 40 and 50, and the compressed air generated by the supercharging of the turbochargers 40 and 50 is supplied to the intake system. Thus, a torque curve TQ2 at the time of twin turbo with a high shaft torque in a high rotation speed region is obtained.

On the other hand, if it is determined in step S63 that Tp ≦ Tp1, that is, that the current operation region has shifted to the single turbo region (see FIG. 22) at the boundary of the twin → single switch determination line L1, the process proceeds to step S66. Referring to the value of the determination value search flag F4, the process proceeds to step S67 if F4 = 0, and to step S69 if F4 = 1.
Go ahead.

The determination value search flag F4 is cleared when the engine is in the twin turbo range and the engine load Tp is in the twin turbo range with the engine load Tp bordering on the twin → single switching determination line L1 (Tp1).
4). Therefore, after Tp <Tp1, the first routine is executed, the process proceeds to step S67, and based on the engine load Tp, the single turbo region continuation time determination value T is referenced by referring to the single turbo region continuation time determination value table with interpolation calculation.
Set 4. This set value T4 is a reference value for switching to a single turbo state in which only the primary turbocharger 40 operates after a predetermined time has elapsed after the engine operating state has shifted from the twin turbo region to the single turbo region.

FIG. 32 is a conceptual diagram of a single turbo area continuation time determination value table. The single turbo region continuation time determination value T4 set according to the engine load Tp is:
For example, the maximum value is set to 2.3 sec and the minimum value is set to 0.6 sec. The value is set to a smaller value as the value of the engine load Tp is larger and higher. As a result, after the engine operating state shifts from the twin turbo region to the single turbo region, the time until the engine is switched from the twin turbo state to the single turbo state is accelerated as the engine load is higher, and a portion where the shaft torque in the twin turbo state is low is reduced. Operation in the vehicle is prevented, and the re-acceleration is improved.

Next, after setting the judgment value search flag F4 in step S68, the process proceeds to step S69. In step S69, after counting up the single turbo region duration time count value C2, in step S70, the determination value T4 is compared with the count value C2, and if C2 ≧ T4,
After proceeding to step S73 to clear the count value C2, the process returns to step S19 to switch from the twin turbo state to the single turbo state. Thereby, each switching solenoid valve SOL. 1 to 4 are turned off, the supercharging pressure relief valve 57 is opened, and the intake control valve 55 and the exhaust control valve 53
Are both closed, the state is switched from a twin turbo state in which both turbochargers 40 and 50 operate to a single turbo state in which only the primary turbocharger 40 operates.

The switching state at this time is shown by a time chart as shown by the solid line in FIG. As described above, the switching from the twin turbo state to the single turbo state is performed when the engine operation range shifts from the twin turbo region to the single turbo region (Tp ≦ Tp1) and the state continues for the set time (C2 ≧ T4). , And unnecessary switching of the supercharger due to a temporary decrease in the engine speed N associated with the shifting of the transmission is prevented.

Here, the single turbo region continuation time determination value T4 giving the set time is set to a shorter time as the value of the engine load Tp is higher and the load is higher, and the switching to the single turbo state is accelerated. That is, high torque is required at the time of engine high-load operation, but as shown in FIG. 35, the torque provided by the shaft torque curve TQ2 at the time of the twin turbo on the single turbo region side with respect to the twin → single switching determination line L1 For example, the torque (point B in the figure) given by the shaft torque curve TQ1 at the time of single turbo is higher than the point A) in the figure, and if the twin turbo state is maintained in this region, sufficient shaft torque cannot be obtained. However, the output performance deteriorates, and the re-acceleration performance also deteriorates.

For this reason, when the engine is under a high load, the switching from the twin turbo state to the single turbo state is speeded up by setting the single turbo region duration time determination value T4 to a short value, and the torque in the twin turbo state is increased. The operation is quickly switched to the single-torque state with a high torque by minimizing the operation in the low-pressure region (from point A to point B in FIG. 35).
The output performance is improved and the re-acceleration performance is also improved.

Further, during low load operation, the motor is in the low torque state, the torque difference between the twin turbo operation and the single turbo operation is small, and the switching from the twin turbo operation to the single turbo operation can be performed with sufficient setting time. Almost no torque fluctuation. For this reason, at the time of a low load, after the engine operation area shifts from the twin turbo area to the single turbo area at the boundary of the twin → single switching determination line L1, the state is changed to a relatively long time given by the single turbo area duration determination value T4. After the continuation, by switching from the twin turbo state to the single turbo state, unnecessary switching of the supercharger due to a temporary decrease in the engine speed N is effectively and reliably avoided.

On the other hand, in step S70, C2 <T4
In the case of, the process proceeds to step S71, and the throttle opening TH
Is compared with a set value TH3 (for example, 30 deg).
If H> TH3, the process proceeds to step S1 through step S73.
Returning to FIG. 9, even after the engine operation region shifts to the single turbo region and before the state continues for the set time, the engine immediately switches to the single turbo state as shown by the broken line in FIG. 57 is opened,
The exhaust control valve 53 and the intake control valve 55 are both closed to stop the supercharging operation of the secondary turbocharger 50, and only the primary turbocharger 40 is switched to the single turbo state of the supercharging operation.

The set value TH3 is for determining an acceleration request. That is, in the single turbo range (Tp <Tp1), as shown in the output characteristics of FIG. 35, the twin-single switching determination line L1 is on the low rotation side,
This is a region where the shaft torque of the torque curve TQ2 at the time of twin turbo is low, and if the twin turbo state is maintained in this state,
Even if the accelerator pedal is depressed, sufficient acceleration performance cannot be obtained. Therefore, when it is determined that an acceleration request is made when driving in this region (TH> TH3),
Immediately shifting to the single turbo state to make the single turbo state, and obtaining the torque curve TQ1 of the high shaft torque at the time of the single turbo, thereby improving the acceleration response.

If TH ≦ TH3 in step S71, the process proceeds to step S72, in which the vehicle speed VSP and the set value V
SP2 (for example, 2 km / h), and VSP> V
If it is determined in SP2 that the vehicle is running, the process proceeds to step S74, where the twin turbo state is maintained, and VS
When it is determined that the vehicle is in the stopped state with P ≦ VSP2, the process returns to step S19 via step S73 in the same manner as described above, and immediately shifts to the single turbo state.

The set value VSP2 is for judging the stop state of the vehicle. When the vehicle is stopped, for example, at idle speed, the accelerator is depressed and the engine is idly blown.
The engine speed N increases with an increase in the engine load Tp, and the engine operation region shifts from the single turbo region to the twin turbo region, enters a twin turbo state, and after the accelerator is released, the engine load Tp and the engine speed N are increased. Immediately decreases, and the engine operation area changes to twin →
When shifting to the single turbo region again with the single switching determination line L1 (see FIG. 22 or FIG. 30) as a boundary, after switching to the single turbo region, the single turbo state is not switched unless the set time has elapsed (C2 ≧ T4). During this time, the engine speed N decreases and drops to near the idle speed (for example, near 700 rpm), and then each switching solenoid valve SOL. Switching from 1 to 4 is performed, and the supercharging pressure relief valve 57 and each of the control valves 53 and 55 are switched.

At this time, since the engine speed is low, the background noise due to the engine rotation is low, and the sound generated when each valve is switched is heard by the driver, giving the driver discomfort. For this reason, when it is determined that the vehicle is stopped, (V
SP ≦ VSP2), even after the set time has not passed after the shift to the single turbo range (C2 <T4), by immediately switching to the single turbo state, before the engine speed decreases and the background noise decreases. The switching of each valve is completed, and the discomfort caused by the noise of the valve operation is eliminated. The switching state from the twin turbo state to the single turbo state at this time is shown by a one-point line in FIG.

Subsequently, the above-described supercharging pressure control in each turbo state is described by a supercharging pressure control routine of FIGS. 7 to 12 and FIGS.
7 DUTY1 calculation routine, DUTY of FIGS.
This will be described with reference to a flowchart showing a Y2 calculation routine. Each of these routines is performed by the ignition switch 96.
Is turned on, the process is executed with the set time and priority described in FIG. When the power is supplied to the ECU 100 by turning on the ignition switch 96, the system is initialized (each flag and each count value are cleared).

In the following description, first, in the single turbo state, special conditions such as engine stall and start, when low-octane number regular gasoline is used, when a special mode to be described later is selected, when an absolute pressure sensor malfunctions, and when the throttle is fully closed to decelerate. The determination of the state and the supercharging pressure control in the special state will be described, and the supercharging pressure control in the normal state will be described. Next, a description will be given of the supercharging pressure control in the case of passing through the small opening area of the exhaust control valve at the time of switching from single to twin, and then the supercharging pressure control in the twin turbo state. And furthermore, twin →
A description will be given of the supercharging pressure control with and without passing through the small opening area of the exhaust control valve at the time of single switching.

Therefore, first, a special state and a normal state are determined in a supercharging pressure control routine. That is, the engine speed N is referred to in step S100, and if N = 0, the process proceeds to step S1.
01, turning on and off the ignition switch 96
Refer to the F state. And the ignition switch 9
If 6 is OFF, it is determined that the engine is stopped and step S10
2 and the switching solenoid valve for secondary waste gate valve SOL. W is turned off and the process proceeds to step S112.

Also, the ignition switch 96 is turned on.
And when the state of N = 0 continues for a predetermined time or more,
The engine stall in the special state is determined, and the routine proceeds from step S101 to step S111, where the switching solenoid valve for secondary wastegate valve SOL. Turn W on. Then, in step S112, the special state determination-time control determination flag FREG
Is set, and in step S113, the primary wastegate control duty solenoid valve D. is set. SOL. The duty ratio DUTY1 for determining the control signal for 1 is set to 0
Fix to%.

Therefore, in the engine stall control, the secondary wastegate valve switching solenoid valve SOL. W ON
By doing so, the compressor downstream of the secondary turbocharger 50 communicates with the secondary wastegate valve actuating actuator 52 to prepare for regular determination control.
The primary wastegate control duty solenoid valve D.D. SOL. 1 duty ratio DUTY1 is 0%
, The primary wastegate control duty solenoid valve D. SOL. 1 is fully closed, the compressor downstream of the primary turbocharger 40 communicates directly with the primary wastegate valve operating actuator 42,
Be prepared for a drop in exhaust pressure when starting the engine.

On the other hand, when the engine is operated with N ≠ 0, the process proceeds from step S100 to step S103 and thereafter, and the used fuel is determined using the overall correction coefficient of the ignition timing learning control and the ignition partial correction map. That is, in the ignition timing learning control,
An area where the total correction coefficient TCMP is equal to or less than the set value TCWGC and the value of the partial correction ignition timing learned for each engine operation area after the completion of learning of the entire correction coefficient in the ignition partial correction map is equal to or less than the set value PCWGC1 [deg]. Set number PC
After detecting a state of WGC2 or more, the overall correction coefficient T
CMP is the set value TCWGCR (where TCWGCR> T
Until CWGC), it is determined that low-octane-number regular gasoline is used, and otherwise, it is determined that high-octane-number high-octane gasoline is used. The ignition timing learning control is described in Japanese Patent Application Laid-Open No.
No. 966, it is possible to determine whether to use regular gasoline or high-octane gasoline based on this.

Therefore, in step S103, the first initial value 0 is referred to by referring to the regular discrimination flag FTCMP.
In step S104, the overall correction coefficient TCMP of the ignition timing learning control is compared with the set value TCWGC in step S104.
If> TCWGC, it is determined that high-octane gasoline is used. If TCMP ≦ TCWGC, step S
At 105, the set value PCWGC1 [de of the partial correction map
g] is compared with the set number PCWGC2, and when PCW <PCWGC2, it is similarly determined that high-octane gasoline is used. When PCW ≧ PCWGC2, the process proceeds to step S106, and once determined that regular gasoline is used. The regular discrimination flag FTCMP is set.

If FTCMP = 1, the process proceeds from step S103 to step S107, where the overall correction coefficient T
Compare the CMP with the set value TCWGC,
If P ≦ TCWGC, it is determined that regular gasoline is used, and if TCMP> TCWGC, it is determined that high-octane gasoline is used, and the regular determination flag FTCMP is cleared in step S108. In this manner, when it is determined that regular gasoline is used, a special state is set in step S101.
Proceed to.

If it is determined that high-octane gasoline is used, the flow advances to step S109 to refer to the use state of the test mode switch 123 outside the ECU 100. If the test mode switch 123 is ON with the connector connected, the flow advances to step S110 to read the memory switch. Reference is also made to the usage state of 124.
If the read memory switch 124 is OFF, the process proceeds to step S114, where the read memory switch 12
If 4 is also ON, it is determined that the special mode has been selected by inspection at the line end of the factory or repair inspection by the dealer, and in this case also, the process proceeds to step S101 as a special state.

In this manner, when the engine stalls, when regular gasoline is used, or when the special mode is selected, the process proceeds to step S101. In this case, when the ignition switch is ON, the secondary solenoid valve switching solenoid valve SOL. Turn W on. Thereafter, in step S112, the special state determination control determination flag FREG is set, and in step S113, the duty ratio DUTY1 is fixed at 0%.

On the other hand, when the special mode is not selected with the use of high-octane gasoline, the process proceeds from step S109 or step S110 to step S114, and the switching solenoid valve for secondary wastegate valve SOL. W to O
FF is performed, and then the presence or absence of a failure of the absolute pressure sensor 81 is referred to in step S115. Then, when the absolute pressure sensor 81 fails, the process proceeds from step S115 to step S112 to be in a special state.

When the absolute pressure sensor 81 is normal,
Proceeding from step S115 to step S116, the operation state of the throttle opening sensor 85 is referred to. If the throttle is fully closed after the engine is started or during deceleration, step S117 is performed.
Then, the process proceeds to step S112, where the initial value setting flag FIDL is set. Therefore, when the absolute pressure sensor 81 fails or in a special state when the throttle is fully closed, the secondary wastegate valve switching solenoid valve S
OL. With the W turned off, the primary wastegate control duty solenoid valve D.D. SOL. The duty ratio DUTY1 of the control signal for 1 is fixed to 0%.

Accordingly, as a control at the time of engine stall, even when high-octane gasoline is used, when the throttle is fully closed after the engine is started, the primary wastegate control duty solenoid valve D.C. SOL. Duty ratio D of control signal to 1
UTY1 is set to 0%. Therefore, when the engine is started, the primary wastegate control duty solenoid valve D.D. SOL. 1 is fully closed, the pressure downstream of the compressor of the primary turbocharger 40 directly acts on the pressure chamber of the actuator 42 for operating the primary wastegate valve, and the primary wastegate valve 41 is easily opened.
As a result, the exhaust pressure is sufficiently reduced when the engine is started, and the startability is improved.

Next, if it is determined in step S116 that the throttle valve is to be opened in the normal state of using high-octane gasoline, the flow advances to step S118 to refer to the initial value setting flag FIDL, and when FIDL = 1, that is, when starting, When the valve is opened after the throttle is fully closed as in step S1
Go to 19 and set the duty ratio DUTY1 to the initial value DUID
The flag is set to OF, and then the initial value setting flag FIDL is cleared in step S120. Then, step S1
At 21, the control state flag FREG for special state determination is cleared, and the routine proceeds to step S130. When the throttle valve is open, the process jumps from step S118 to step S121.

Next, the supercharging pressure control in the single turbo state will be described. First, in step S130 of the supercharging pressure control routine, the switching calculation in-operation flag FRUN is cleared. Then, in step S131, the switching solenoid valve SOL. 2 referring to the ON / OFF state,
Switching solenoid valve for intake control valve SOL. 2 is OFF and the intake control valve 55 is closed, the switching solenoid valve SOL. 1 ON, O
Referring to the FF state, the switching solenoid valve SOL. When 1 is OFF and the supercharging pressure relief valve 57 is also closed, it is determined that the state is the single turbo state, and the process proceeds to step S146.

Then, in the single turbo state, first, a single-to-twin-time initial value setting flag FTWIN is set in step S146. Then, step S140
At the time of switching from twin to single operation determination flag FSIN
With reference to G, the process proceeds to step S147 with the initial value 0, and the single turbo transition time count value CSING is cleared.

After that, the process proceeds to a step S160 to refer to the value of the twin turbo discrimination flag F1. Therefore, immediately after the ignition switch 96 is turned on, and when the current control state is the single turbo, F1 = 0, so that the process proceeds to step S161 to refer to the value of the supercharging pressure control mode determination flag F2. This boost pressure control mode determination flag F2
Since the initial setting is performed immediately after the ignition switch 96 is turned on and F2 = 0 when the operation area is outside the exhaust control valve small opening control mode at the time of the previous execution of the routine, the process proceeds to step S162, and the process proceeds to step S162 to step S164. It is determined whether or not the mode has been shifted to the exhaust control valve small opening control mode by the condition determination of (1).

As shown in FIG. 24, the transition to the exhaust control valve small opening control mode is determined based on the relationship between the engine speed N and the intake pipe pressure (supercharging pressure) P from the single-twin switching determination line L2. Also, the set values N2 (for example, 2650 rpm) and P2 (for example, 1120 mmHg) on the low rotation and low load side
And the throttle opening TH is equal to the set value T.
When H2 (for example, 30 deg) or more, it is determined that the mode has shifted to the exhaust control valve small opening control mode.

That is, in step S162, the engine speed N is compared with the set value N2, in step S163, the intake pipe pressure P is compared with the set value P2, and in step S164, the throttle opening TH and the set value TH2 are compared. Compare. If N <N2, P <P2, or TH <TH2, it is determined that the current operation region is the primary wastegate control mode outside the exhaust control valve small opening region, and step S170 is performed.
Then, the supercharging pressure control mode determination flag F2 is cleared. On the other hand, when N ≧ N2, P ≧ P2, and TH ≧ TH2, it is determined that the current operation region has shifted to the exhaust control valve small opening control mode in the exhaust control valve small opening region, and step S16 is performed.
Proceeding to 8, the supercharging pressure control mode determination flag F2 is set.

If F2 = 1 in step S161, the process proceeds from step S161 to step S165,
It is determined whether or not the current operation region has shifted to the primary wastegate control mode by the condition determination in steps S165 to S167. The determination of the transition to the primary wastegate control mode is performed, as shown in FIG. 24, in order to prevent control hunting at the time of switching to the boost pressure control mode, as shown in FIG. (For example, 2600 rpm), P1 (for example, 1070 mmHg), TH1 (for example, 25 deg)
Performed by

That is, in step S165, the engine speed N is compared with the set value N1, in step S166, the intake pipe pressure (supercharging pressure) P is compared with the set value P1, and in step S167, the throttle opening TH is determined. It compares with the set value TH1, and if N <N1 or P <P1 or TH <TH1, it is determined that the current operation area has shifted to the primary wastegate control mode, and the process proceeds to step S170 described above.
The supercharging pressure control mode determination flag F2 is cleared. Thereby, the exhaust control valve small opening control is released. Also, N <N
If 1 and P ≧ P1 and TH ≧ TH1, it is determined that the current operation area is still in the exhaust control valve small opening control mode, and the routine proceeds to step S168, where the supercharging pressure control mode determination flag F2 is set to F2. = 1 and the exhaust control valve small opening control is continued.

In the case of the primary wastegate control mode in which F2 = 0, steps S170 to S1
Proceeding to 71, an initial value setting flag FINI2 at the time of transition to the exhaust control valve small opening control mode is set, and in step S172,
The count value CINI2 for measuring the elapsed time after shifting to the exhaust control valve small opening control mode is cleared. Thereafter, in step S173, the in-operation calculation execution flag FRUN is executed.
Since FRUN = 0 in step S130, the process proceeds to step S174, where the supercharging pressure control mode determination flag F2 is referenced. Since F2 = 0, the process proceeds to step S175 to refer to the initial value setting flag FINI1 at the time of transition to the primary wastegate control mode, and jump to step S181 by the initial setting.

In step S181, referring to the special state determination control determination flag FREG, when the special state determination of FREG = 1 (step S112) proceeds to step S182, the exhaust control valve small opening control duty solenoid valve D.D.
SOL. The duty ratio DUTY2 for determining the control signal for the control signal No. 2 is compared with the regular control upper limit value DU2MX2 (about 47% or less). And DUTY2 <DU2
In the case of MX2, the process jumps to step S184, where D
If UTY2 ≧ DU2MX2, the upper limit value DU2MX2 is set to the duty ratio DUTY2 in step S183.

Thereafter, in step S184, the duty ratio DUTY1 is set to the primary wastegate control duty solenoid valve D.D. SOL. In step S185, the duty ratio DUTY2 is set as the duty ratio of the control signal for the exhaust control valve small open control duty solenoid valve D.1. SOL. Set as the duty ratio of the control signal for 2 and exit from the routine. Also, FREG = 0
Otherwise, the process jumps from step S181 to step S184.

Here, the DUTY1 calculation in the special state will be described. In the DUTY1 calculation routine, first, at step S200, the special state determination time control determination flag FREG is determined.
In the case of the special state determination of FREG = 1,
Exit the routine. In the normal state of FREG = 0, the routine proceeds to step S201, where the supercharging pressure control mode determination flag F2 is referred to. In the exhaust control valve small opening control mode of F2 = 1, the routine proceeds to step S202, and the exhaust control valve small opening control mode is set. The transition initial value setting flag FINI2 is referred to. As a result, FINI2 = 0, and as will be described later, after the elapse of the set time after the shift to the exhaust control valve small opening control mode (C
If (INI2 ≧ TMDRY), the process exits the routine similarly. Therefore, in the special state, after the set time has elapsed after the shift to the exhaust control valve small opening control mode, in any case, the respective calculations are given priority and the DUTY1 calculation routine does not perform the calculation, and the primary wastegate valve 41
Is not performed.

Next, the DUTY2 operation will be described.
In step S300 of the DUTY2 calculation routine, the supercharging pressure control mode determination flag F2 is referred to, and in the primary wastegate control mode in which F2 = 0, the routine is exited. Further, in the exhaust control valve small opening control mode in which F2 = 1, the switching calculation execution flag F
With reference to RUN, the routine exits as it is during the execution of the calculation at the time of switching of FRUN = 1. Also, FRUN = 0
In step S302, the initial value setting flag FINI2 at the time of transition to the exhaust control valve small opening control mode is referred to, and FIN
If I2 = 1 and the set time after the shift to the exhaust control valve small-opening control mode has elapsed (CINI2 <TMDRY), the routine is exited.

Therefore, in the primary wastegate control mode, during the execution of the calculation at the time of switching, or within the set time after the shift to the exhaust control valve small opening control mode, in any case,
In the DUTY2 calculation routine, the calculation is not performed with priority given to each calculation, and the supercharging pressure feedback control by the exhaust control valve 53 is not performed.

On the other hand, in step S302, FIN
After a lapse of a set time after the shift to the exhaust control valve small opening control mode of I2 = 0 (CINI2 ≧ TMDRY), the process proceeds to step S303, and the special state determination time control determination flag FRE is performed.
See G. Then, at the time of the special state determination of FREG = 1, the routine jumps to step S347 to jump to the duty ratio DU.
The lower limit value DU2MN2 is set in TY2, and step S3
51, the duty ratio DUTY2 is changed to the exhaust control valve small opening control duty solenoid valve D. SOL. The duty ratio of the control signal for 2 is set and the routine exits.

Therefore, in the supercharging pressure control in the special state,
In the control at the time of regular determination, the overall correction coefficient TCMP of the learning variable of the ignition timing learning control and the number of areas P of the partial correction map
The use of regular gasoline is accurately determined by the CW, and when it is determined that regular gasoline is used, the switching solenoid valve SOL.
W and the primary wastegate control duty solenoid valve D.W. SOL. 1. The duty ratio DUTY1 of the control signal for 0 is fixed to 0%, and the exhaust control valve small opening control duty solenoid valve D. SOL. The duty ratio DUTY2 of the control signal with respect to the predetermined upper limit value DU2MX2 and the lower limit value DU
Control with MIN2.

Therefore, in the primary wastegate control mode under the single turbo, the duty ratio DUTY1 is fixed to 0% at the time of regular determination, so that the primary wastegate control duty solenoid valve D.C. S
OL. 1 is fully closed, and the pressure downstream of the compressor of the primary turbocharger 40 directly acts as a control pressure on the pressure chamber of the actuator 42 for operating the primary wastegate valve. Therefore, the opening degree of the primary wastegate valve 41 increases, and the actual supercharging pressure decreases.

Further, in the exhaust control valve small opening control mode under a single turbo, the duty ratio DU
TY2 is controlled within the range of the regular control upper limit value DU2MX2 or less, so that the exhaust control valve small opening control duty solenoid valve D.T. SOL. 2, the positive pressure in the positive pressure chamber 54a of the exhaust control valve actuating actuator 54 increases, and the small opening degree of the exhaust control valve 53 increases. The switching solenoid valve for secondary wastegate valve SOL. When W is turned on, the duty ratio DUTY1 is fixed at 0%, the wastegate valves 41 and 51 are opened, and the exhaust gas leaks, so that the actual supercharging pressure is reduced.

Further, under the twin turbo in the special state, the duty ratio DUTY1
Is fixed to 0%, the opening degree of the primary wastegate valve 41 increases. Further, the switching solenoid valve SOL. When W is turned on, the positive pressure downstream of the compressor of the secondary turbocharger 50 acts on the pressure chamber of the actuator 52 for operating the secondary wastegate valve, so that the secondary wastegate valve 51 is also opened, and the actual supercharging is performed. The pressure is reduced.

Thus, even when using regular gasoline,
The supercharging pressure is controlled based on the target supercharging pressure for high-octane gasoline, and the control is simplified. Then, when regular gasoline is used, the actual supercharging pressure is uniformly reduced in the entire region as shown by the broken line in FIG. 43 as compared with when normal high-octane gasoline is used, whereby knocking is effectively avoided in the entire region. You.

On the other hand, when the high-octane gasoline in the normal state is used, the switching solenoid valve SOL. W turns off and secondary wastegate valve 5
1 is closed. Also, supercharging pressure feedback control is performed based on a target supercharging pressure set for high-octane gasoline, whereby the actual supercharging pressure is controlled to be higher as a whole as shown by the solid line in FIG. 43, and an engine high output is obtained. .

In the control at the time of selecting the special mode, the test mode switch 123 outside the ECU 100 is used for the inspection at the line end of the factory or the repair or inspection by the dealer.
The special mode is forcibly determined by connecting and turning on the read memory switch 124 by a connector or the like.

When the special mode is selected, the switching solenoid valve SOL. Turn on W,
D. Primary wastegate control duty solenoid valve SOL. Duty ratio DUT of control signal for 1
Y1 is fixed at 0%, and the exhaust control valve small opening control duty solenoid valve D. SOL. The duty ratio DUTY2 of the control signal with respect to 2 is controlled within a range of a predetermined regular control upper limit value DU2MX2 or less. For this reason, the actual supercharging pressure is reduced uniformly in all regions as compared with the normal state.

Thus, by measuring the supercharging pressure state when the normal state and the special mode are selected, it is possible to easily inspect and check whether the control is appropriately performed. At this time,
Each duty solenoid valve D. SOL. 1, D. SO
L. 2 is measured, and the duty solenoid valves D. SOL. 1, D. SOL. 2 can be performed, and the switching solenoid valve SOL. The operation state of W can be confirmed. In the normal state, the test mode switch 123 and the read memory switch 124 are both disconnected.

Next, control when the absolute pressure sensor fails will be described. If the absolute pressure sensor 81 fails, detection of the intake pipe pressure (actual supercharging pressure) and the atmospheric pressure becomes impossible. At this time, if the supercharging pressure feedback control is performed based on the abnormal output value of the absolute pressure sensor 81, the supercharging may have an adverse effect on the engine, or the supercharging may be insufficient, and the traveling performance may be deteriorated.

For this reason, when the output value of the absolute pressure sensor 81 does not change for a predetermined time or more in the engine operating state and a failure of the absolute pressure sensor 81 is diagnosed, the duty ratio DUTY1 is fixed at 0%. In addition, the duty ratio DUTY2 is controlled within the range of the regular control upper limit value DU2MX2 (about 47%) or less. At this time, the secondary solenoid valve switching solenoid valve SOL. W is O
FF is performed, and the secondary wastegate valve 51 is closed. Also, when determining the use of regular gasoline described above,
Prioritize control during regular judgment.

Therefore, in the primary wastegate control mode under the single turbo, the duty ratio DUTY1 is fixed to 0% when the absolute pressure sensor failure is determined, so that the primary wastegate control duty solenoid valve D.C. SOL. 1 is fully closed, and the pressure downstream of the compressor of the primary turbocharger 40 acts directly as a control pressure on the primary wastegate valve operating actuator 42. For this reason, the opening degree of the primary wastegate valve 41 is increased as compared with the normal state, and the actual supercharging pressure is subjected to open loop control according to the pressure downstream of the compressor, so that the actual supercharging pressure is reduced.

In the exhaust control valve small opening control mode under the single turbo, when the absolute pressure sensor failure is determined, the duty ratio DUTY2 is controlled within the range of the regular control upper limit value DU2MX2 or less. The degree of opening increases. Further, the duty ratio DUTY1 is fixed to 0%, the primary wastegate valve 41 is opened, and the exhaust gas leaks, so that the actual supercharging pressure is reduced.

Further, under the twin turbo, when the failure of the absolute pressure sensor is determined, the duty ratio DUTY1 is similarly fixed at 0%, so that the opening degree of the primary wastegate valve 41 is increased and the actual supercharging pressure is reduced. Be lowered. In this case, the switching solenoid valve S for the secondary wastegate valve is used.
OL. W turns off and secondary wastegate valve 5
The valve 1 is closed, and the actual supercharging pressure increases by this amount. Therefore,
When the absolute pressure sensor fails, the actual supercharging pressure is controlled to be lower than the normal state and higher than when the regular gasoline is used, as indicated by the dashed line in FIG. 43, thereby preventing the supercharging or the supercharging shortage. In addition, good running performance is ensured while keeping the engine safe.

Further, control when the throttle is fully closed will be described. At the beginning of the deceleration operation in which the throttle valve 21 is closed from the open state, the exhaust energy decreases with a predetermined delay. For this reason, supercharging by the turbocharger continues despite the throttle being fully closed, and the intake pressure between the downstream of the compressor and the upstream of the throttle valve rises rapidly, causing intake noise and surging of the turbocharger.

To cope with this, the outlet side of the intercooler 20 upstream of the throttle valve and the upstream side of the compressor of the primary turbocharger 40 are communicated via a bypass passage 46, and the intake negative pressure downstream of the throttle valve is connected to the bypass passage 46. An air bypass valve 45 is provided which opens when the throttle valve is fully closed so that the intake pressure trapped downstream of the compressor leaks. But air bypass valve 4
5 alone is not sufficient, especially when decelerating from a twin turbo state.
Due to the supercharging operation of 0,50, the intake pressure sharply increases, and it is difficult to eliminate intake noise and surging of the turbocharger.

Therefore, when the throttle is fully closed, the duty ratio DUTY1 is fixed at 0%, and the duty ratio DUTY1 is fixed.
Y2 is controlled within a range equal to or less than the upper limit value DU2MX2. Therefore, when the throttle is fully closed during deceleration, the duty ratio DU
By fixing TY1 to 0%, the primary wastegate control duty solenoid valve D.T. SOL. 1 is fully closed, and the pressure downstream of the compressor of the primary turbocharger 40 acts directly as a control pressure on the primary wastegate valve operating actuator 42. For this reason, the exhaust energy falls with a delay, and during this time, if the turbocharger continues to be supercharged and the intake pressure downstream of the compressor rises sharply, the primary wastegate valve 41 is opened by this intake pressure and the exhaust is relieved. .

Further, by controlling the duty ratio DUTY2 within a range not more than the preset upper limit value DU2MX2, the exhaust control valve 53 is gradually closed from the open state. For this reason, for example, in a twin turbo, the supercharging capacity of both the primary and secondary turbochargers 40 and 50 is rapidly reduced, and the rise of the intake pressure downstream of the compressor and the upstream of the throttle valve is effectively suppressed. Noise and surging of the turbocharger are reliably prevented.

Next, a case where it is determined that the valve is to be opened from the fully closed state of the throttle will be described. Duty ratio DUTY1 is PI
When the boost pressure feedback control is started by the primary wastegate valve 41 after being set by the control, there are the following problems. That is, since the change rate of the duty ratio DUTY1 due to the P and I components is small and the duty ratio DUTY1 is gradually increased from the state of DUTY1 = 0%, the duty ratio is determined based on the deviation between the target supercharging pressure and the actual supercharging pressure. It takes time until the ratio DUTY1 converges to a predetermined value.
During this time, the control followability of the actual supercharging pressure with respect to the target supercharging pressure is deteriorated, causing a change in the supercharging pressure, and the drivability is deteriorated.

For this reason, if it is determined that the throttle is fully opened from the fully closed state in the normal state, the above-described control is immediately stopped, and the duty ratio DUTY1 is set to the initial value DUIDOF (step S119 of the supercharging pressure control routine). Therefore, the primary wastegate valve 41 immediately sets the initial value DUID.
It opens to an opening degree corresponding to the OF and changes from the opening degree, and the followability of the actual supercharging pressure to the target supercharging pressure is improved.

Next, the supercharging pressure control in the primary wastegate control mode under the single turbo state will be described. In this case, as described above, the duty ratio DUTY2 is not calculated due to F2 = 0, the exhaust control valve 53 is fully closed and remains uncontrolled, and the opening of the primary wastegate valve 41 is calculated by calculating the duty ratio DUTY1. Is changed and the boost pressure feedback control is performed.

Therefore, in step S203 of the DUTY1 calculation routine, the process proceeds to step S204 by F1 = 0, and based on the engine speed N and the throttle opening TH,
The target target boost pressure TPTAGTM in the single turbo state under the standard atmospheric pressure is set with reference to the single turbo target boost pressure map with interpolation calculation.

[0205] The single turbo target boost pressure map is used to set the target boost pressure for the boost pressure control on the assumption that high-octane gasoline is used and the engine has been completely warmed up in a single turbo state under standard atmospheric pressure. The optimum value obtained by simulation or experiment is stored in advance using the engine speed N and the throttle opening TH as parameters, and the engine speed N is high and the throttle opening TH is The larger the value is, the higher the target boost pressure is.

Here, for example, the basic target supercharging pressure TPTAGTM with respect to the engine speed N is set as shown in FIG. 38. In the single turbo state, the basic target supercharging pressure TPTAGTM smoothly increases in accordance with the increase in the engine speed N. Then it will be a certain height. In the twin turbo state, the basic target boost pressure TPTAGTM is set to a still higher constant value according to a twin turbo target boost pressure map described later.
It should be noted that even when using regular gasoline, the same target supercharging pressure map is used to control the actual supercharging pressure in a uniformly reduced state.

Thereafter, the process proceeds to step S205, in which the basic target supercharging pressure TPTAGTM corresponding to the standard atmospheric pressure is set to the atmospheric pressure A.
Based on the atmospheric pressure (absolute pressure) ALT detected by the absolute pressure sensor 81, a supercharging atmospheric pressure correction coefficient KALCOM for correcting the decrease with the decrease of LT is calculated by a linear function expression based on the atmospheric pressure ALT shown below. Set. KALCOM ← KALC11 × ALT−KALC01 (2) where KALC11 and KALC01 are constants

That is, when the supercharging pressure control is performed by the absolute pressure, the basic target supercharging pressure TPTAGTM corresponding to the standard atmospheric pressure is used.
When the target supercharging pressure is set as it is, the differential pressure between the target supercharging pressure and the atmospheric pressure becomes large in high altitude running at low atmospheric pressure, etc. The rotation speed of the turbocharger 40 becomes relatively high. For this reason, in an environment where the atmospheric pressure is lower than the standard atmospheric pressure, the engine operation state is determined by the engine speed N and the engine load Tp.
In order to obtain a predetermined target supercharging pressure, the primary turbocharger 40 is not supercharged, although it does not exceed the above-mentioned overspeed determination line (see FIG. 29) in the single turbo state determined from the relationship. There is a possibility of rotation.

[0209] The overspeed of the turbocharger is determined by the air flow rate of the turbocharger and the pressure ratio between the upstream and downstream of the turbocharger, and the air flow rate changes due to a difference in air density due to a change in atmospheric pressure. . As is clear from the equation of state of the gas, the relationship between the atmospheric pressure and the air density is represented by a linear function in which the air density decreases as the atmospheric pressure decreases. Therefore, the basic target supercharging pressure TPTAGTM corresponding to the standard atmospheric pressure is calculated. A supercharging atmospheric pressure correction coefficient K for correcting a decrease as the atmospheric pressure decreases.
ALCOM can be set by a linear function using the atmospheric pressure ALT.

FIG. 36 shows the relationship between the atmospheric pressure ALT and the supercharging atmospheric pressure correction coefficient KALCOM according to the above equation (2).
As is clear from the figure, the constant K in the above equation (2)
ALC11 gives a gradient of the atmospheric pressure correction coefficient KALCOM at the time of supercharging, and a constant KALC01 gives an intercept. These constants KALC11 and KALC01 determine an optimum value in advance by simulation or experiment or the like.
06 is stored as fixed data.

Specifically, as shown in FIG. 36, in the present embodiment, each constant KALC11, KALC01
When the atmospheric pressure ALT is the standard atmospheric pressure (760 mmHg), the supercharging atmospheric pressure correction coefficient KALCOM is set to KALCOM = 1.0 corresponding to the state without correction, and the atmospheric pressure ALT is set.
The atmospheric pressure correction coefficient at the time of supercharging KALCOM is decreased with the decrease of the pressure, for example, when ALT = 400 mmHg, KALCOM
COM is set to a value that gives 0.7.

Thus, the supercharging atmospheric pressure correction coefficient KALCOM for correcting the basic target supercharging pressure TPTAGTM corresponding to the standard atmospheric pressure by the atmospheric pressure is calculated by a simple linear function equation based on the atmospheric pressure ALT. A table for storing the supercharging atmospheric pressure correction coefficient KALCOM using the atmospheric pressure ALT as a parameter, and no interpolation calculation when setting the supercharging atmospheric pressure correction coefficient KALCOM with reference to the table is completely unnecessary, thereby using the memory capacity. In addition, the processing for setting the supercharging atmospheric pressure correction coefficient KALCOM is simplified, and the calculation load on the CPU 105 of the main computer 101 constituting the ECU 100 when setting the supercharging atmospheric pressure correction coefficient KALCOM is remarkably reduced. It is possible to do.

When the supercharging atmospheric pressure correction coefficient KALCOM is given by a table, the supercharging atmospheric pressure correction coefficient KALCOM is set according to each atmospheric pressure ALT corresponding to the grid of the table.
On the other hand, when the supercharging atmospheric pressure correction coefficient KALCOM is set by a linear function expression as in the present embodiment, two constants KALC11 and KAL11 given in the linear function expression are set.
Since only C01 (in the case of the twin turbo state, constants KALC12 and KALC02 will be determined as described later), setting can be performed very easily.

In addition, the turbo capacity is small, and most of the exhaust gas is introduced into the primary turbocharger 40, and the single turbo state with high responsiveness is obtained. The turbo capacity is large, and the exhaust gas is the secondary turbocharger 40 and the secondary turbocharger. In the twin turbo state distributed and introduced to the turbocharger 50, the single turbo state has a higher possibility of overspeed due to the decrease in the atmospheric pressure ALT. The possibility of overspeed of the turbocharger is slightly lower than in the case of single turbo. Therefore, the supercharging atmospheric pressure correction coefficient KALCOM for decreasing and correcting the basic target supercharging pressure TPTAGTM set in the twin turbo state as described later is represented by a broken line in FIG.
Supercharging atmospheric pressure correction coefficient KALC in single turbo state
It is set slightly larger than OM, and the rate of decrease correction becomes relatively small.

Next, in steps S206 to S209, the supercharging atmospheric pressure correction coefficient KALCOM is regulated to an upper limit and a lower limit. In other words, the atmospheric pressure correction is required to prevent the turbocharger from over-rotating when the atmospheric pressure is lower than the standard atmospheric pressure, and in the region above the standard atmospheric pressure, the above equation (2) is used. If the basic target supercharging pressure TPTAGTM corresponding to the standard atmospheric pressure is corrected using the supercharging atmospheric pressure correction coefficient KALCOM calculated by the linear function as it is, the supercharging pressure is unnecessarily increased. There is a risk that the turbocharger will over rotate.

For this reason, in the present embodiment, when the atmospheric pressure ALT is the standard atmospheric pressure (760 mmHg), the supercharging atmospheric pressure correction coefficient KALCOM is set to KALCOM = 1.0 corresponding to the state without correction. In consideration of this, the upper limit value for the supercharging atmospheric pressure correction coefficient KALCOM is set to 1.
In step S206, the supercharging atmospheric pressure correction coefficient KALCOM calculated by the above equation (2) is compared with 1.0 corresponding to the upper limit value. And KALCO
When M> 1.0, the upper limit is set at step S207 by setting the supercharging atmospheric pressure correction coefficient KALCOM to 1.0 (KAL
COM ← 1.0), and proceeds to step S210.

In step S206, KAL
When COM ≦ 1.0, the process proceeds to step S208,
The supercharging atmospheric pressure correction coefficient KALCOM is set to the lower limit ALCOM
Compare with MIN1. That is, the supercharging atmospheric pressure correction coefficient KALC calculated by the linear function of the above equation (2)
Since the OM is set to decrease with a decrease in the atmospheric pressure ALT, the supercharging-time atmospheric pressure correction coefficient KA calculated by the linear function equation of the equation (2) in a low atmospheric pressure state below a predetermined atmospheric pressure.
If LCOM is used as it is and the target supercharging pressure TPTAGTM corresponding to the standard atmospheric pressure is corrected to set the target supercharging pressure, the supercharging is reduced and the supercharging pressure is reduced, resulting in insufficient output.

Therefore, in step S208, the supercharging atmospheric pressure correction coefficient KALCOM is compared with the lower limit ALCOMMIN1, and when KALCOM <ALCOMMIN1, the routine proceeds to step S209, where the supercharging atmospheric pressure correction coefficient KAL
The lower limit of ALCOM is regulated by the lower limit ALCOMMIN1 (KALCOM ← ALCOMMIN1), and the process proceeds to step S210. In the present embodiment, the lower limit A
As shown in FIG. 36, for example, the LCOMMIN1 has an atmospheric pressure ALT corresponding to ALT = 400 mmHg.
7 is set.

In step S208, KAL
When COM ≧ ALCOMMIN1, the supercharging atmospheric pressure correction coefficient KALCOM is set to the upper limit 1.0 and the lower limit ALCO
Because it is located between MMIN1 (ALCOMMI
N1 ≦ KALCOM ≦ 1.0), step S2
Proceed to 10.

In step S210, the water temperature sensor 83 detects a water temperature correction coefficient KTWCOM for correcting the basic target supercharging pressure TPTAGTM on the premise of completion of engine warm-up as the cooling water temperature TW representing the engine temperature decreases. Based on the cooling water temperature TW to be set, it is set by a linear function equation based on the cooling water temperature TW shown in the following equation. KTWCOM ← KTW11 × TW−KTW01 (3) where KALC11 and KALC01 are constants

That is, when the engine is cold, the lubrication of each part is not perfect due to the low viscosity of the oil that lubricates each part of the engine, and the temperature of the combustion chamber is also low, and the combustion state is unstable. In such a state, if an attempt is made to obtain a boost pressure similar to that in the engine warm-up completed state, the intake air density increases due to a decrease in the air temperature despite the insufficient mechanical operation of the engine. As a result, it becomes the same as the supercharging, and not only the occurrence of misfire and the fluctuation of the combustion pressure increase, but also a local abnormal increase of the combustion pressure is caused, which may adversely affect the engine.
In particular, immediately after the engine is started at an extremely low temperature, the friction is large and the combustion state is unstable, which may cause a failure of the engine.

For this reason, based on the cooling water temperature (for example, 50 ° C.) at the time of completion of engine warm-up, the water temperature correction coefficient KTW is set such that the lower the cooling water temperature TW, the lower the target supercharging pressure.
By performing the decrease correction on the basic target supercharging pressure TPTAGTM by the COM, it is possible to prevent the occurrence of trouble due to the supercharging when the engine is cold, and to improve the durability and reliability of the engine.

Here, under the same atmospheric pressure condition, the relationship between the air density and the air temperature is expressed by a linear function equation in which the air density increases as the air temperature decreases, as is clear from the equation of state of the gas. . Further, since the air temperature depends on the engine temperature, the engine temperature is represented by the cooling water temperature TW, and the basic target supercharging pressure TPTAG in the warm-up completed state.
Water temperature correction coefficient KTWCOM for TM correction
Can be set by a linear function equation based on the cooling water temperature TW.

FIG. 37 shows the relationship between the cooling water temperature TW and the water temperature correction coefficient KTWCOM according to the above equation (3). As is clear from the figure, the constant KTW11 in the above equation (3)
Gives the slope of the water temperature correction coefficient KTWCOM, and gives the constant KT
W01 gives the intercept, and each of these constants KTW1
1, KTW01 is obtained in advance by calculating the optimum value by simulation or experiment, and is stored in the ROM 106 as fixed data.

Specifically, as shown in FIG. 37, in the present embodiment, the constants KTW11 and KTW01 are
When the cooling water temperature TW is the warm-up completion temperature, the water temperature correction coefficient KT
KTWCOM = WCOM = corresponding to the state without correction
1.0, and the water temperature correction coefficient K
Decrease TWCOM.

Also in this case, in the twin turbo state, the possibility of occurrence of a malfunction due to an increase in the supercharging pressure due to a decrease in the engine temperature is slightly lower than in the single turbo state. Therefore, the water temperature correction coefficient KTWCOM for decreasing and correcting the basic target supercharging pressure TPTAGTM set in the twin turbo state as described later is, as shown by the broken line in FIG. 37, the water temperature correction coefficient KTWC in the single turbo state.
It is set slightly larger than OM, and the rate of decrease correction becomes relatively small.

Thus, a water temperature correction coefficient KTWCOM for correcting the basic target supercharging pressure TPTAGTM in accordance with the cooling water temperature TW on the assumption that the engine has been completely warmed up is calculated by a simple linear function equation based on the cooling water temperature TW. By using the cooling water temperature TW as a parameter, the water temperature correction coefficient K
A table for storing the TWCOM and an interpolation calculation for setting the water temperature correction coefficient KTWCOM with reference to the table are not required at all, thereby reducing the amount of memory used and simplifying the processing for setting the water temperature correction coefficient KTWCOM. When setting the water temperature correction coefficient KTWCOM,
C of the main computer 101 constituting the ECU 100
It becomes possible to remarkably reduce the calculation load on the PU 105.

Further, a water temperature correction coefficient KTW is obtained from a table.
When COM is given, the water temperature correction coefficient KTWCOM must be set in accordance with each cooling water temperature TW corresponding to the grid of the table. On the other hand, as in the present embodiment, the water temperature correction coefficient KTWCOM is calculated by a linear function equation. Coefficient KTWC
When OM is set, two constants KTW11 and KTW01 given in the linear function expression (in the case of the twin turbo state, the constants KTW12 and KTW0 as described later)
Since only 2) is determined, setting can be performed very easily.

Next, in steps S211 to S214, the water temperature correction coefficient KTWCOM for correcting the basic target supercharging pressure TPTAGTM according to the engine temperature is increased.
Lower limit. That is, in the engine temperature state after the completion of the warm-up, the basic target supercharging pressure TPTAGTM corresponding to the standard atmospheric pressure is directly used by using the supercharging atmospheric pressure correction coefficient KALCOM calculated by the linear function equation of the above equation (2).
Is overcorrected, and the supercharging pressure is unnecessarily increased.

Even when the engine is in a cold state before the completion of warming-up, the supercharging atmospheric pressure correction coefficient KALCOM calculated by the linear function of the above equation (3) is used as it is, and the basic target corresponding to the standard atmospheric pressure is used. If the supercharging pressure TPTAGTM is corrected, the overcharging is similarly performed, and the supercharging pressure becomes too low to obtain the required engine output, not only delaying the warm-up progress, but also not obtaining the required engine output, It may induce the driver to depress the accelerator, and adversely affect the engine.

For this reason, in the present embodiment, the cooling water temperature TW is set to the temperature at the time of completion of engine warm-up (for example, 50 ° C.).
° C), the upper limit value of the water temperature correction coefficient KTWCOM is set to 1 in consideration of the fact that the water temperature correction coefficient KTWCOM is set to KTWCOM = 1.0 corresponding to the state without correction.
In step S211, the water temperature correction coefficient KTWCOM calculated by the above equation (3) is compared with 1.0 corresponding to the upper limit value. Then, KTWCOM> 1.
When it is 0, the water temperature correction coefficient KTWCO is determined in step S212.
M is set to 1.0 and the upper limit is regulated (KTWCOM ← 1.
0), and proceed to step S215.

In step S211, KTW
When COM ≦ 1.0, the process proceeds to step S213,
The water temperature correction coefficient KTWCOM is set to the lower limit value TWCOMMIN1.
When KTWCOM <TWCOMMIN1, the routine proceeds to step S214, where the water temperature correction coefficient KTWCO
M is regulated by a lower limit TWCOMMIN1 (K
TWCOM ← TWCOMMIN1), Step S215
Proceed to. In step S213, KTWCO
When M ≧ TWCOMMIN1, the water temperature correction coefficient KT
Since WCOM is between the upper limit 1.0 and the lower limit TWCOMMIN1, (TWCOMMIN1 ≦ KTW
COM ≦ 1.0), and directly proceeds to step S215.

In steps S215 to S224, the basic target supercharging pressure TPTA is set according to the gear position of the automatic transmission 153.
A gear position correction coefficient KGP for reducing and correcting GTM is set. That is, the transmission 150 of the present embodiment has the vehicle speed V
The shift speed of the automatic transmission 153 is controlled to be switched according to a shift characteristic preset based on the SP and the throttle opening TH. For this reason, if the accelerator pedal is depressed in a stopped state in which the brake is depressed in the driving range other than the neutral range and the P range, the shift stage of the automatic transmission 153 is not upshifted, and an excessive load is applied to the brake band and the clutch. This may cause a problem. In particular, if a stall to fully open the accelerator is performed in a stopped state where the brake is depressed in the travel range, the same supercharging pressure as in the fully opened travel is applied, and the automatic transmission 153 is driven by excessive driving force.
There is a strong possibility that a failure will occur in the transmission 150 including.

Therefore, in the single turbo mode, when the vehicle speed is equal to or lower than the set vehicle speed at which the vehicle can be considered to be in a stopped state and is in the traveling range, the basic target supercharging pressure T
By setting a gear position correction coefficient KGP for reducing and correcting PTAGTM and reducing the target supercharging pressure by the gear position correction coefficient KGP, the transmission 150 is protected in response to idling or stall in a stopped state. Note that, when the vehicle is stopped by stepping on the brake in the traveling range, the primary turbocharger 40 is operated in a single turbo state. Therefore, the correction using the gear position correction coefficient KGP is substantially performed only in the single turbo mode. It is effective for

Therefore, first, at step S215, the vehicle speed V
The SP is compared with a set value TBSTSP (for example, 4 to 5 km / h) corresponding to the stopped state to determine whether there is a possibility of a stall. If VSP ≧ TBSTSP, it is determined that there is no possibility of a stall, and the process proceeds to step S224, where the gear position correction coefficient GEAR is set to 1.0 corresponding to the state without correction.

In step S215, VSP <TBS
In the case of the TSP, it is determined that there is a possibility of a stall depending on the gear position, and the gear position correction coefficient KGP is set in steps S216 to S223 according to the gear position GEAR. That is, in step S216, the gear position GEAR
Is 1st (1st speed) or not, and gear position GEAR is 1
At the time of st, at step S217, the gear position correction coefficient KG
Set the set value GP1 to P and set the gear position GEAR to 1s
If not, the gear position GEA is determined in step S218.
It is checked whether R is 2nd (2nd speed).

If the gear position GEAR is 2nd, the set value GP2 is set to the gear position correction coefficient KGP in step S219. If the gear position GEAR is not 2nd, the gear position GEAR is set to 3 in step S220.
It is checked whether it is rd (3rd speed) or more. As a result, when the gear position GEAR is 3rd or more, step S22
At step 1, the set value GP3 is set to the gear position correction coefficient KGP.

If the gear position GEAR is not 3rd or more in step S220, step S22
The program proceeds to 2 to check whether the gear position GEAR is in the reverse range. If the gear position GEAR is in the reverse range, the set value GPR is set to the gear position correction coefficient KGP in step S223, and the gear position is set. Is not in the position of the reverse range, that is, when the neutral range or the P range is selected, there is no possibility of a stall, so the process proceeds to step S224 described above, and the gear position correction coefficient KGP is in a state without correction. Set the corresponding 1.0.

Each set value GP1, GP2, GP3, GPR
Since the load applied to the transmission 150 increases as the gear ratio increases, the value decreases in the order of GP3> GP2 ≧ GP1> GPR, and the set value GPR corresponding to the reverse gear position with the largest gear ratio is obtained. The maximum correction amount of the target supercharging pressure is the largest, for example, GPR = 0.5 to 0.7, and G corresponding to a gear position of 3rd or more where the gear ratio is small.
The reduction correction amount of the target supercharging pressure by P3 is GP3 = 1.0 substantially without correction.

Then, the above steps S217 and S21
After setting the gear position correction coefficient KGP according to the gear position GEAR in any one of 9, S221, S223, and S224, the routine proceeds to step S245, where the basic target supercharging pressure TPTA is set.
The target supercharging pressure TPTAGT is calculated as follows by multiplying the GTM by the supercharging atmospheric pressure correction coefficient KALCOM, the water temperature correction coefficient KTWCOM, and the gear position correction coefficient KGP. TPTAGT ← TPTAGTM × KALCOM × KTW
COM × KGP

Accordingly, the target supercharging pressure TPTAGT is set higher as the engine load increases, and the traveling performance is improved. On the other hand, when the atmospheric pressure becomes lower than the standard atmospheric pressure at a high altitude or the like, the target supercharging pressure TPTAGT is corrected so as to be lower, thereby preventing the turbocharger from over-rotating. Also,
When the engine temperature is lower than the warm-up completion temperature, the target supercharging pressure TPTAGT is corrected so as to be lower, and adverse effects on the engine are avoided to improve reliability. further,
Even if the accelerator is depressed while the transmission is in the travel range and the brake is depressed and the vehicle is stopped, the target supercharging pressure is set low in advance according to the gear position GEAR in the travel range. The transmission 150 is not hung, and no trouble occurs in the transmission 150.

Thereafter, the flow proceeds to step S250, referring to the twin turbo discrimination flag F1, and proceeds to step S251 with F1 = 0 because of the single turbo state, and based on the engine speed N and the throttle opening TH, the single turbo The basic control duty DUTY1B in the single turbo state is set by referring to the basic control duty map MPDTY11 with interpolation calculation.

The single-turbo basic control duty map MPDTY11 indicates an appropriate primary wastegate control duty for obtaining the target boost pressure by changing the opening of the primary wastegate valve 41 in the single turbo under standard atmospheric pressure. Solenoid valve D. SOL. The basic value of the duty ratio DUTY1 for 1 is obtained in advance by simulation or experiment using the engine speed N and the throttle opening TH as parameters and stored as a map.

In this embodiment, the primary wastegate control duty solenoid valve D. SOL. As the duty ratio of 1 increases, the control pressure on the primary wastegate valve operating actuator 42 decreases, the opening degree of the primary wastegate valve 41 decreases, and the actual supercharging pressure increases. As the throttle opening TH increases, the basic control duty DUTY1B increases to increase the actual supercharging pressure in response to the increase in the target supercharging pressure.

Next, the routine proceeds to step S253, where the target supercharging pressure TPTAGT is compared with a set value FBTGT (for example, FBTGT corresponding to the idling operation state = 400 mmHg). And if TPTAGT <FBTGT,
Feedback P (proportional gain) and feedback I
In order to stop the PI control of the supercharging pressure by the minute (integral gain), the feedback P component P1 is set to 0 in step S254, and the feedback I component I1 is also set to 0 in step S255. Then, the process proceeds to step S278, where the duty ratio DUTY1 is calculated by adding the feedbacks P and I, P1 and I1 to the basic control duty DUTY1B. In this case, the duty ratio DUTY1 is equal to the basic control duty DUTY1B itself. Become.

Next, the flow advances to step S279, in which the duty ratio DUTY1 calculated in step S278 is set to the lower limit value D.
DUTY1 ≦ DU compared to UMIN (for example, 0%)
If MIN, the duty ratio DU is set in step S280.
TY1 is set as a lower limit value DUMIN, and the duty ratio DUTY1 is set to a primary wastegate control duty solenoid valve D. in step S287. SOL. It is set as the duty ratio of the control signal to 1.

If the duty ratio DUTY1 calculated in step S278 is larger than the lower limit value DUMIN (DUTY1> DUMIN), the flow advances from step S279 to step S281 to refer to the supercharging pressure control mode discriminating flag F2 and to determine the primary waist. In the gate control mode, the process proceeds to step S284 when F2 = 0, and the upper limit value DUMAX1 is set by referring to the table with interpolation calculation based on the engine speed N and the throttle opening TH.

The table of the upper limit value DUMAX1 contains the primary wastegate control duty solenoid valve D. S
OL. As the duty ratio of 1 increases, the control pressure on the primary wastegate valve operating actuator 42 decreases, the opening degree of the primary wastegate valve 41 decreases, and the actual supercharging pressure increases. The lower the throttle opening TH, the higher the upper limit value DUMAX
1, the upper limit value DUMAX1 decreases as the engine speed N increases and the throttle opening TH decreases.

Then, in a step S285, the duty ratio DUTY1 is compared with the upper limit value DUMAX1, and the duty ratio DUTY1 is determined.
If ≧ DUMAX1, the process proceeds to step S286 to limit the duty ratio DUTY1 to the upper limit value DUMAX1, and in step S287, sets the duty ratio DUTY1 to the primary wastegate control duty solenoid valve DU. SOL. It is set as the duty ratio of the control signal to 1.

In step S285, DUTY
If 1 <DUMAX1, the process jumps from step S285 to step S287, and uses the duty ratio DUTY1 calculated in step S278 as it is to change the primary wastegate control duty solenoid valve D.1. SO
L. It is set as the duty ratio of the control signal to 1.

That is, in the idling operation state where the target supercharging pressure TPTAGT is lower than the set value FBTGT (for example, 400 mmHg), if the supercharging pressure feedback control is performed by the P and I components, the duty ratio DUT by the P and I components is obtained.
Since the rate of change of Y1 is small, it takes time until the duty ratio DUTY1 converges to a predetermined value based on the difference between the target supercharging pressure and the actual supercharging pressure. The followability is degraded, causing a change in the supercharging pressure, and the drivability is rather degraded. For this reason, the target boost pressure TPTAG
When T is lower than the set value FBGTGT, the basic control duty DUTY1B set based on the engine speed N and the throttle opening TH is regulated between the upper limit value DUMAX1 and the lower limit value DUMIN, and is used. By controlling the opening degree of the valve 41 in an open loop, the convergence of the actual supercharging pressure P to the target supercharging pressure TPTAGT is expedited, and the operability is improved.

Next, the target boost pressure TPTAGT is set to the set value F.
The supercharging pressure control in a normal running state of BTGT or higher will be described. In this case, the process proceeds from step S253 to step S256 to execute the PI control of the supercharging pressure by the feedback P component P1 and the hood back I component I1, and refers to the twin turbo discrimination flag F1. Then, the process proceeds to step S257 for the single turbo state of F = 1, and the set value KGP1 for setting the feedback P component P1 according to the deviation between the target supercharging pressure TPTAGT and the actual supercharging pressure P.
Is set to the single turbo set value KGP11,
In step S259, the difference (TPTAGT-P) between the target supercharging pressure TPTAGT and the actual supercharging pressure P is multiplied by a set value KGP1 to set a feedback P component P1.

When the actual supercharging pressure P exceeds the target supercharging pressure TPTAGT, the feedback P component P1 becomes a negative value corresponding to the deviation (TPTAGT-P), and decreases the duty ratio DUTY1. It acts so as to immediately reduce the actual supercharging pressure P. When the actual boost pressure P matches the target boost pressure TPTAGT, the feedback P
The minute P1 becomes 0, and as described later, the feedback I minute I1 at that time also becomes a constant value, and the duty ratio DU
TY1 is kept constant. When the actual supercharging pressure P becomes lower than the target supercharging pressure TPTAGT, the deviation (TPTA
GT-P) and the duty ratio D
It acts to increase UTY1 and immediately increase the actual supercharging pressure P. For this reason, the target boost pressure TP of the actual boost pressure P
The deviation from TAGT is immediately reflected in the feedback P component P1, and good responsiveness is obtained.

In this case, when the feedback P is set by using a table, the target supercharging pressure T of the actual supercharging pressure P is set.
The magnitude of the increase in the actual supercharging pressure is determined by determining the magnitude relationship with respect to the PTAGT, and the decreasing amount of the P for decreasing the actual supercharging pressure is determined by the actual supercharging pressure P and the target supercharging. Pressure T
Processing such as setting in a separate process with reference to a table using the deviation from PTAGT as a parameter is required, and the setting process becomes complicated. Further, in the table for setting the up amount or the down amount for P, the up amount or the down amount for the deviation that does not directly correspond to the grid of the table is set by interpolation calculation, or the same up amount or the down amount in a predetermined range of the deviation. And the like, and it is not always possible to obtain the feedback P component accurately corresponding to the deviation of the actual supercharging pressure P from the target supercharging pressure TPTAGT.

On the other hand, in the present embodiment, the feedback P component P1 is directly set by an arithmetic expression for multiplying the deviation (TPTAGT-P) between the target supercharging pressure TPTAGT and the actual supercharging pressure P by the set value KGP1. , A table of the amount of P increase or the amount of P decrease, the target boost pressure TP of the actual boost pressure P
By referring to the table after judging the magnitude relation with respect to the TAGT, complicated processing for setting the up amount or the down amount for P becomes unnecessary, and the memory usage capacity is reduced.
In addition to reducing the load on the CPU 105 of the main computer 101 constituting the ECU 100 when setting the feedback P component P1, it is possible to accurately cope with a deviation of the actual supercharging pressure P from the target supercharging pressure TPTAGT. Thus, the feedback P component P1 can be obtained, and control responsiveness can be improved and precise control can be realized.

Thereafter, in order to restrict the feedback P component P1 set in step S259 to a controllable range,
In steps S260 to S263, the feedback P amount P1
Above and below the lower limit. That is, in step S260, the feedback P component P1 is compared with the lower limit value P1MIN. If P1 ≦ P1MIN, the feedback P component P1 is set to the lower limit value P1MIN in step S261, and the lower limit is regulated, and the process proceeds to step S264.

In step S260, P1> P
If 1 MIN, the feedback P component P1 is compared with the upper limit P1MAX in step S262, and P1 ≦ P1
MAX, and feedback P is lower limit value P1MIN
If the value falls within the range between the upper limit value P1MAX and the upper limit value P1MAX, the process directly jumps to step S264, where P1> P1MA
If X, the feedback P component P1 is determined in step S263.
Is set as the upper limit P1MAX, and the process proceeds to step S264.

From step S264, the target supercharging pressure T
A feedback I component I1 is set according to the difference (TPTAGT-P) between PTAGT and the actual supercharging pressure P. For this reason,
First, in step S264, the difference (TPTAGT-P) between the target supercharging pressure TPTAGT and the actual supercharging pressure P is calculated by using the target supercharging pressure T
Set value I that defines the upper limit of the control dead zone for PTAGT
Compare with DNDP.

The set value IDNDP is equal to the target boost pressure TPTA.
In order to evaluate the magnitude relationship between GT and the actual supercharging pressure P with a sign, when the actual supercharging pressure P becomes higher than the target supercharging pressure TPTAGT, the deviation (TPTAGT-P) becomes a negative value. Correspondingly, the upper limit of the dead zone is set to the target boost pressure TPTA.
This is indicated by a value in the minus direction from GT. In addition, the lower limit of the dead zone corresponds to the fact that the deviation (TPTAGT-P) becomes a positive value when the actual supercharging pressure P becomes lower than the target supercharging pressure TPTAGT.
It is indicated by a value in the plus direction from the target boost pressure TPTAGT using P.

Then, in step S264, the TPT
If AGT-P ≧ IDNDP and the actual supercharging pressure P is equal to or less than the upper limit of the dead zone, the process proceeds from step S264 to step S26.
Proceeding to 5, the deviation (TPTAGT-P) between the target supercharging pressure TPTAGT and the actual supercharging pressure P is compared with a set value IUPDP that determines the lower limit of the dead zone. Then, IUPDP ≧ TPTA
GT-P, and the actual boost pressure P is in the dead zone (TPTAG
If (T-IDNDP ≧ P ≧ TPTAGT−IUPDP), the I component update amount DI is determined in step S266.
The process jumps to step S273 by setting 1 to 0, and calculates the current feedback I component I1 by adding the current I component update amount DI1 to the previous feedback I component I1. In this case, the feedback I component I1 has the same value as the previous time.

After calculating the feedback I component I1, the process proceeds from step S273 to step S274 to restrict the feedback I component I1 to a controllable range, and compares the feedback I component I1 with the lower limit I1MIN. As a result, the feedback I component I1 is reduced to the lower limit I1.
If it is not more than MIN, the lower limit I1MIN is set to the feedback I component I1 in step S275, and the duty ratio DUTY1 is calculated by adding the feedback P component P1 and the feedback I component I1 to the basic control duty DUTY1B in step S278. .

The feedback I component I1 is equal to the lower limit I
If it is greater than 1 MIN, the process proceeds from step S274 to step S276, where the feedback I component I1 is compared with the upper limit I1MAX. The feedback I component I1 is equal to or less than the upper limit value I1MAX, and the lower limit value I1MIN.
If the value falls within the range between the upper limit value I1MAX and the upper limit value I1MAX, the process directly jumps to step S278 to add the feedback P component P1 and the feedback I component I1 to the basic control duty DUTY1B, and the duty ratio DUTY1
Is calculated.

The feedback I component I1 is equal to the upper limit I
If it exceeds 1MAX, the upper limit I1MAX is set to the feedback I component I1 in step S277, and the upper limit is regulated. In step S278, the basic control duty D
The duty ratio DUTY1 is calculated by adding the feedback P component I and the feedback I component I1 to UTY1B.

Then, in step S279, the duty ratio DUTY1 is compared with the lower limit value DUMIN.
Ratio DUTY1 and upper limit value DUMAX at 285
The upper limit and lower limit of the duty ratio DUTY1 are regulated after comparison with the primary wastegate control duty solenoid valve D.1 in step S287. SOL. It is set as the duty ratio of the control signal to 1.

Therefore, the actual supercharging pressure P becomes equal to the target supercharging pressure TPAT.
The target supercharging pressure T of the actual supercharging pressure P is in the dead zone of the AGT.
Feedback I for slight deviations from PTAGT
If the adjustment by the component I1 is not valid, the updating of the feedback I component I1 is stopped, and the target supercharging pressure T of the actual supercharging pressure P is stopped.
The opening degree of the primary wastegate valve 41 is controlled such that the actual supercharging pressure P converges to the target supercharging pressure TPTAGT by adjusting the duty ratio DUTY1 by the feedback P component P1 proportional to the amount of deviation from PTAGT.

That is, in the conventional PI control, when the actual supercharging pressure enters the dead zone of the target supercharging pressure, the control by the feedback P and feedback I components is stopped, and the actual supercharging pressure is reduced to the target supercharging pressure. Although it is difficult to perform precise control to match the values, in the present embodiment, even when the supercharging pressure is within the dead zone of the target supercharging pressure, the deviation between the actual supercharging pressure and the target supercharging pressure is not considered. Since the actual supercharging pressure is controlled to be equal to the target supercharging pressure by the feedback P which is set in proportion to the above, extremely precise supercharging pressure control can be realized. Further, by setting the upper limit value DUMAX1 and the lower limit value DUMIN to the duty ratio DUTY1, the supercharging pressure control by the primary wastegate valve 41 is always performed in a controllable region.

Next, when the actual supercharging pressure P is out of the dead zone and exceeds the upper limit IDNDP of the dead zone, the process proceeds from step S253 to step S256, where F1 = 0.
From step S257 to step S259, the deviation (TPT) between the target supercharging pressure TPTAGT and the actual supercharging pressure P
AGT-P) is multiplied by the set value KGP1 to reset the feedback P component P1. In this case, the feedback P
The component P1 is a negative value corresponding to the difference between the actual supercharging pressure P and the target supercharging pressure TPTAGT, and the duty ratio DUTY1
To decrease the actual supercharging pressure P.

Thereafter, the upper and lower limits of the feedback P P1 are regulated in steps S260 to S263, and in step S264, the deviation (TPTAGT-P) between the actual supercharging pressure P and the target supercharging pressure TPTAGT is determined by the upper limit of the dead zone. TPTAGT-P <IDND
The process proceeds to step S267 by P to refer to the twin turbo discrimination flag F1. Then, when F1 = 0, the process proceeds to step S268, where the I-component update amount DI1 is reduced by the amount-IDN.
1 is set, and in step S273, the present feedback I component I1 is added to the previous feedback I component I1 to calculate the current feedback I component I1.

Further, in steps S274 to S277, the feedback I component I1 is set to the upper limit I1MAX and the lower limit I1.
Upper and lower limits are set between MIN and MIN. In step S278,
The duty ratio DU is determined by the basic control duty DUTY1B, the feedback P component P1, and the feedback I component I1.
Set TY1. Then, steps S279 to S28
In step S287, the duty ratio DUTY1 is regulated between the upper limit value DUMAX1 and the lower limit value DUMIN. SOL. 1
Is set as the duty ratio of the control signal for.

Therefore, the actual supercharging pressure P becomes equal to the target supercharging pressure TPTA.
If the actual supercharging pressure P deviates from the target supercharging pressure TPTAGT in proportion to the deviation of the actual supercharging pressure from the target supercharging pressure TPTAGT, the primary wastegate control duty solenoid is controlled by the feedback P component P1 when the actual supercharging pressure P deviates from the target supercharging pressure TPTAGT. Valve D. SOL. The duty ratio DUTY1 of 1 is relatively greatly reduced, and at the same time, the duty ratio DUTY1 is slightly reduced by the feedback I component I1 reduced by the down amount -IDN1.

Therefore, the opening degree of the primary wastegate valve 41 increases in the same relationship with the control pressure of the actuator 42 for operating the primary wastegate valve, and the actual supercharging pressure P rapidly decreases toward the target supercharging pressure TPTAGT. At the same time, it is finely adjusted near the target boost pressure TPTAGT,
The actual supercharging pressure P decreases quickly and smoothly. Then, when the vehicle enters the dead zone of the target supercharging pressure TPTAGT, step S
In steps 257 and S259, the feedback P component P2 is reset, and the feedback P in steps S260 to S263 is reset.
From step S264 to step S2 after the upper and lower limits of the minute P2
The process advances to step S266 via I / O 65, and the I component update amount DI
1 is set to 0, and the updating of the feedback I component I1 is stopped.

If the actual supercharging pressure P is lower than the lower limit of the dead zone and deviates from the dead zone, step S253 is executed.
Then, the process proceeds to step S256, and the process proceeds from step S257 to step S259 according to F1 = 0, and the target supercharging pressure TP
The difference (TPTAGT-P) between TAGT and the actual supercharging pressure P is multiplied by the set value KGP1 to reset the feedback P component P1. In this case, the feedback P component P1 is
The duty ratio DUTY1 increases as a positive value corresponding to the difference between the actual boost pressure P and the target boost pressure TPTAGT,
It acts in a direction to increase the actual supercharging pressure P.

Then, after the upper and lower limits of the feedback P component P1 are regulated in steps S260 to S263, the result of comparison between the deviation (TPTAGT-P) in step S264 and the set value IDNDP for setting the upper limit of the dead zone is calculated as T
The process proceeds to step S265 according to PTAGT-P ≧ IDNDP, and compares the deviation (TPTAGT-P) with a set value IUPDP that defines the lower limit of the dead zone.

As a result, IUPDP <TPTAGT-P
Then, the process proceeds to step S270 to refer to the twin turbo discrimination flag F1, and if F1 = 0, the process proceeds to step S271 to set the up amount IUP1 to the I component update amount DI1. Then, in step S273, the current feedback I component I1 is added to the previous feedback I component I1 to calculate the current feedback I component I1, and steps S274 to S27 are performed.
7, the upper and lower limits of the feedback I component I1 are regulated, and in step S278, the basic control duty DUTY1 is set.
B, feedback P component P1, feedback I component I1
Sets the duty ratio DUTY1.

Therefore, the actual supercharging pressure P is equal to the target supercharging pressure TPTA.
When the control pressure becomes lower than the lower limit of the control dead zone for the GT, the primary wastegate control duty solenoid valve D. is controlled by the feedback P component P1 which is updated in proportion to the deviation of the actual boost pressure P from the target boost pressure TPTAGT. SOL. The duty ratio DUTY1 is relatively large, and at the same time, the duty ratio DUTY1 is increased by the feedback I component I1 which is increased by the up amount IUP1.
1 is slightly increased.

Therefore, the opening degree of the primary wastegate valve 41 decreases in the same relationship with the control pressure of the primary wastegate valve operating actuator 42, and the actual supercharging pressure P rapidly increases toward the target supercharging pressure TPTAGT. At the same time, it is finely adjusted near the target boost pressure TPTAGT,
The actual boost pressure P rises quickly and smoothly to the target boost pressure TP
Entering the dead zone of TAGT, feedback I minute I1
Is stopped, and the feedback P component P is proportional to the deviation between the actual supercharging pressure P and the target supercharging pressure TPTAGT.
1 is set, and the actual boost pressure P is always the target boost pressure TPTAG.
Feedback control is performed so as to follow T.

That is, in the conventional feedback control of the supercharging pressure based on the feedbacks P and I, when the actual supercharging pressure deviates from the dead zone of the target supercharging pressure, the first operation cycle on the side shifted in the same direction from the dead zone. Is performed to adjust the actual boost pressure to the target boost pressure only by the feedback P, and the feedback I
Since fine tuning is performed to make the actual supercharging pressure gradually converge in the dead zone by only the minute, it takes time for the actual supercharging pressure to converge in the control dead zone to the target supercharging pressure, and the drivability deteriorates. However, in the present embodiment, when the actual supercharging pressure is out of the dead zone of the target supercharging pressure, the adjustment by the feedback P and the fine adjustment by the feedback I are simultaneously performed in the same calculation cycle. By doing so, the actual supercharging pressure quickly converges in the dead zone, and even if the actual supercharging pressure is in the dead zone, the feedback P component proportional to the deviation between the actual supercharging pressure and the target supercharging pressure is obtained. Thus, the actual supercharging pressure is precisely controlled to match the target supercharging pressure. In addition, since the feedback P component P1 and the feedback I component I1 are both controlled within a controllable range, hunting does not occur in the control system due to a sudden operation.

As described above, in the primary wastegate control mode under the single turbo state, the primary wastegate control duty solenoid valve D.D. SOL. 1
The duty ratio DUTY1 of the control signal is set by PI control based on the deviation between the target supercharging pressure TPTAGT and the actual supercharging pressure P, and the upper limit value DUMAX1 and the lower limit value DUM
Upper and lower limits are set between IN. The duty ratio DUTY1 causes the primary wastegate valve 4
1 is increased or decreased, and the supercharging pressure feedback control is performed.

When the vehicle is running in a low altitude at normal atmospheric pressure in a steady or decelerated engine operating state, the basic target supercharging pressure TPTAGTM based on the engine operating state is set to the standard atmospheric pressure by the supercharging atmospheric pressure correction coefficient KALCOM. The target supercharging pressure TPTAGT is set by correcting the deviation from the target turbocharger TPTAGT.
When only 0 operates, a high engine output characteristic is obtained in each operation state. Further, when traveling at high altitude, the target supercharging pressure TPTAG is determined by the supercharging atmospheric pressure correction coefficient KALCOM.
T is corrected to be low overall. Therefore, even when the atmospheric pressure is low, the actual supercharging pressure P is controlled to a value similar to that of a low ground, and the high engine output characteristics are secured.

Next, a description will be given of control when shifting from the primary wastegate control mode to the exhaust control valve small opening control mode when switching the supercharging pressure control mode under the single turbo state.

As described above, the transition to the exhaust control valve small opening control mode under the single turbo state is determined in steps S162 to S164 of the above-described supercharging pressure control routine. That is, in the boost pressure control routine, step S1
At step 71, the initial value setting flag FINI2 at the time of transition to the exhaust control valve small opening control mode is set, and the count value CINI2 is cleared at step S172. In the state of the primary wastegate control mode, steps S162 to S164 are performed.
When it is determined that the mode has shifted to the exhaust control valve small-opening control mode according to the condition determination of (1), the supercharging pressure control mode determination flag F2 is set in step S168, and the process proceeds to step S169 to initialize the primary wastegate control mode initial value setting flag FINI1. Is set, and the process proceeds to step S173.

Therefore, in the exhaust control valve small opening control mode, F
Steps S173 to S17 depending on RUN = 0
4, the process proceeds from step S174 to step S186 by F2 = 1, refers to the initial value setting flag FINI2 at the time of shifting to the exhaust control valve small opening control mode, and proceeds to step S187 by FINI2 = 1. Then, step S18
At step 7, the count value CINI2 is compared with the set value TMDIDLY. At first, the process proceeds to step S188 when CINI2 = 0, and the initial value STDT2 (for example, 75%) is set to the duty ratio DUTY2.

Thereafter, in step S189, the count value C
INI2 is counted up and the above-mentioned step S181 is performed.
The routine proceeds to step S18 in the normal state where FREG = 0.
Jump from step 1 to step S184
In step S5, the duty DUTY2 of the initial value STDT2 is changed to the exhaust control valve small opening control duty solenoid valve D. SOL. 2 is set as the duty ratio of the control signal for 2.

In this case, in the DUTY2 calculation routine,
FRUN = 0 in the exhaust control valve small opening control mode with F2 = 1
Is not being executed at the time of switching, and within the lapse of the set time after the transition to the exhaust control valve small opening control mode with FINI2 = 1 (C
If INI2 <TMDDYLY), the process proceeds from step S300 to step S30 via step S301.
The process proceeds to step S302 and exits the routine from step S302.

On the other hand, in the turbo switching control routine, F2
= 1, the first exhaust control valve switching solenoid valve SOL.
3 is turned on (step S23), and the positive pressure becomes the orifice 67.
Is supplied to the positive pressure chamber 54a of the exhaust control valve actuating actuator 54 through the
Until IDLY elapses, the exhaust control valve small opening control duty solenoid valve D. SOL. 2 is the initial value STDT2
(For example, 75%), and a large amount of positive pressure leaks. Therefore, a relatively low positive pressure control pressure, that is, a pressure slightly higher than the actuator operation minimum pressure ACTmin, is introduced into the positive pressure chamber 54a of the exhaust control valve operation actuator 54, and the pressure sequentially increases, and becomes higher than the minimum pressure ACTmin. At this point, open-loop control is performed so that the exhaust control valve 53 opens slightly.

The set value TMDIDLY that defines the set time after the shift to the exhaust control valve small opening control mode is set to be slightly longer than the supercharging pressure control disabled time until the control pressure reaches the actuator operation minimum pressure ACTmin. Compensation is made so that the supercharging pressure is controlled after the exhaust control valve 53 is surely opened slightly.

At this time, in the DUTY1 calculation routine,
In the normal state, the process proceeds from step S200 to step S202 via step S201 (FREG = 0, F2 = 1), and proceeds from step S203 to step S204 and subsequent steps based on FINI2 = 1. Therefore, at the time of the exhaust control valve small opening control, the duty ratio DUTY1 is set in the same manner as in the above-described primary wastegate control mode, and upper and lower limits are regulated so that the supercharging pressure control is performed in a controllable region. The supercharging pressure feedback control by 41 is continued. However, the upper limit value of the duty ratio DUTY1 is the upper limit value DU of the primary wastegate control mode based on the engine speed N and the throttle opening TH.
MAX1 is restricted to a preset upper limit value DUMAX (for example, 90%).

That is, after comparing the duty ratio DUTY1 with the lower limit value DUMIN in step S279, DU
If the process proceeds to step S281 in which the supercharging pressure control mode determination flag F2 is referred to by TY1> DUMIN, F2 =
In step S282, the duty ratio DU
TY1 is compared with the upper limit value DUMAX. And DU
If TY1 <DUMAX, the process jumps to step S287 to set the duty ratio DUTY1 to the primary wastegate control duty solenoid valve DU. SOL. DUT is set as the duty ratio of the control signal for 1
If Y1 ≧ DUMAX, the duty ratio DUTY1 is limited to the upper limit value DUMAX in step S283, and then in step S287, the duty ratio DUTY1 is set to the primary wastegate control duty solenoid valve DU. SOL. It is set as the duty ratio of the control signal to 1.

The actuator 54 for operating the exhaust control valve has a large capacity, and the orifice 6 is provided in the control pressure passage 73a.
7 is provided and the control pressure itself is adjusted to a low pressure.
It takes time until the control pressure reaches the actuator actuation minimum pressure ACTmin, and during this time, the supercharging pressure control by the exhaust control valve 53 becomes impossible. Therefore, if the control is immediately shifted to the supercharging pressure control by the exhaust control valve 53 when the control mode is switched, the actual supercharging pressure P fluctuates and the operability deteriorates. At this point, when the control mode is switched as described above, the set time TM
The duty ratio DUTY2 is set to the initial value STD in DIDLY.
By setting it to T2, the exhaust control valve 53 is surely slightly opened. By continuing the boost pressure feedback control by the primary wastegate valve 41, the exhaust control valve 53
The supercharging pressure is appropriately controlled even when the supercharging pressure cannot be controlled in the above.

In the supercharging pressure control routine, CIN
If it is determined that I2 ≧ TMDDYLY and the exhaust control valve 53 is substantially opened slightly and it is determined that the supercharging pressure can be controlled by the exhaust control valve 53, the process proceeds from step S187 to step S190 and the initial stage of the transition to the exhaust control valve small open control mode. Value setting flag F
INI2 is cleared, and the count value C is set in step S191.
INI2 is also cleared, and the aforementioned steps S181 to S18 are performed.
Exit the routine via 5.

Therefore, in the DUTY1 calculation routine, the routine exits from the step S202 when FINI2 = 0 in the normal state. In the boost pressure control routine, F
Steps S186 to S1 due to INI2 = 0
Proceed to 92 to refer to the special state determination-time control determination flag FREG. When the special state is determined with FREG = 1, the routine exits from the routine through the above-described steps S181 to S185. In the normal state, the routine proceeds to step S193, where the duty ratio DUTY1 is set to the upper limit value DUMAX (for example, 90%).
Compare with

As a result, if DUTY1 <DUMAX, the duty ratio DUTY1 is increased by a set value DDUTY1 (for example, 1.6%) in step S194, and
If UTY1 ≧ DUMAX, the process proceeds to step S195 to set the upper limit value DUMAX in the duty ratio DUTY1, and jumps from step S181 to step S184 to change the duty ratio DUTY1 of the upper limit value DUMAX to the primary waste gate control duty solenoid valve D. SOL. It is set as the duty ratio of the control signal to 1. Accordingly, the control pressure of the pressure chamber of the primary wastegate valve operating actuator 42 is sequentially reduced by the open loop control, and the primary wastegate valve 41 is closed.

At this time, in the DUTY2 calculation routine,
In the normal state, the process proceeds from step S303 to step S304. As in the case of the primary wastegate control mode, the single turbo target boost pressure map is referred to with interpolation calculation based on the engine speed N and the throttle opening TH, A basic target boost pressure TPTAGTM is set on the assumption that high-octane gasoline is used and engine warm-up is completed in a single turbo state under standard atmospheric pressure.

In step S305, as in the case of the primary wastegate control mode, a supercharging atmospheric pressure correction coefficient for correcting the basic target supercharging pressure TPTAGTM corresponding to the standard atmospheric pressure to decrease as the atmospheric pressure ALT decreases. KA
LCOM is set by a linear function expression based on the atmospheric pressure ALT shown in the above expression (2), and steps S306 to S309 are set.
The supercharging atmospheric pressure correction coefficient KALCOM is raised between 1.0 corresponding to the upper limit and the lower limit ALCOMMIN1.
Lower limit.

Next, in step S310, similarly to the case of the primary wastegate control mode, the basic target supercharging pressure TPTAGTM on the assumption that the engine warm-up is completed is corrected to decrease as the cooling water temperature TW representing the engine temperature decreases. Water temperature correction coefficient KTWCOM is set by a linear function expression based on the cooling water temperature TW shown in the above-described equation (3), and in steps S311 to S314, the water temperature correction coefficient KTWCO
M is 1.0 corresponding to the upper limit and the lower limit TWCOMMI
The upper and lower limits are regulated between N1.

Further, in steps S315 to S324,
As in the case of the primary wastegate control mode, the transmission 15 is determined based on the relationship between the vehicle speed VSP and the gear position GEAR.
When the gear position correction coefficient KGP for decreasing and correcting the basic target supercharging pressure TPTAGTM is set according to the gear position of 0, in step S325, the basic target supercharging pressure TPTAGT is set.
M is multiplied by a supercharging atmospheric pressure correction coefficient KALCOM, a water temperature correction coefficient KTWCOM, and a gear position correction coefficient KGP,
The target boost pressure TPTAGT is calculated.

In step S326, based on the engine speed N and the throttle opening TH, the exhaust control valve basic control duty map MPDTY21 is referred to with interpolation calculation, and the basic control duty in the exhaust control valve small open control mode is determined. Set DUTY2B.

Exhaust control valve basic control duty map MP
The DTY 21 changes the degree of opening of the exhaust control valve 53 and obtains an appropriate exhaust control valve small opening control duty solenoid valve D.D. SOL. The basic value of the duty ratio DUTY2 for 2 is obtained in advance by simulation or experiment using the engine speed N and the throttle opening TH as parameters and stored as a map.

In this embodiment, the exhaust control valve small opening control duty solenoid valve D.V. SOL. As the duty ratio of 2 increases, the control pressure on the exhaust control valve actuating actuator 54 decreases, the small opening degree of the exhaust control valve 53 decreases, and the actual supercharging pressure increases. As the throttle opening TH increases, the basic control duty DUTY2B increases to increase the actual supercharging pressure in response to the increase in the target supercharging pressure.

Then, in step S327, the target boost pressure T
PTAGT and set value FBTGT (for example, 400 mmH
g) and the target boost pressure TPTAGT is set to the set value FB.
If TGT is lower than TGT, the feedback P component P2 is set to 0 in step S328, and the feedback I component I2 is set to a fixed value DTY2MIN (for example, DT2MIN) in step S329.
Y2MIN = 0), the process proceeds to step S345, and the duty ratio DUTY2 is changed to the basic control duty DUTY2.
It is calculated by adding feedback P, I components P2 and I2 to B.

The target boost pressure TPTAGT is equal to the set value F.
If it is equal to or greater than BTGT, the process proceeds from step S327 to step S327.
Proceeding to 330, multiplying the deviation (TPTAGT-P) between the target supercharging pressure TPTAGT and the actual supercharging pressure P by the set value KGP2 to set the feedback P component P2, then step S3
In steps 31 to S334, the feedback P component P2 is regulated between the upper limit value P2MAX and the lower limit value P2MIN, and the target supercharging pressure TPT is determined in steps S335 to S344 as in the case of the primary wastegate control mode.
The feedback I component I2 is set according to the convergence state of the actual supercharging pressure P with respect to the control dead zone of the AGT.

That is, in step S335, the difference between the target supercharging pressure TPTAGT and the actual supercharging pressure P (TPTAGT-
P) is compared with a set value IDNDP that determines the upper limit of the dead zone, and the actual boost pressure P exceeds the upper limit of the control dead zone for the target boost pressure TPTAGT (TPTAGT-P <IDN).
DP), in step S336, the I component update amount DI2
Is set to the down amount-IDNY in step S340.
Thus, the last feedback I minute I2 is added to the I minute update amount DI2
Is added to calculate the current feedback I component I2.
As long as the state in which the actual supercharging pressure P exceeds the upper limit of the dead zone is continued, the above processing is repeated, and the feedback P component P2 is calculated as the deviation between the target supercharging pressure TPTAGT and the actual supercharging pressure P (TPTAGT-P ), And the feedback I component I2 decreases by the down amount-IDNY.

In step S335, when the actual supercharging pressure P falls and becomes lower than the upper limit of the dead zone (T
(PTAGT-P ≧ IDNDP) includes step S335
From step S337 to target boost pressure TPTAGT
And the deviation (TPTAGT-P) between the actual supercharging pressure P and a set value IUPDP that determines the lower limit of the control dead zone. Then, IUPDP ≧ TPTAGT-P, and the actual supercharging pressure P
Is in the dead zone (between the upper and lower limits), the I component update amount DI2 is set to 0 in step S339, and the process jumps to step S340. In this case, the feedback I component I2 becomes the same value as the previous time and the update is stopped,
The actual supercharging pressure P is controlled to converge to the target supercharging pressure TPTAGT by the feedback P component P2 set in proportion to the deviation of the actual supercharging pressure P from the target supercharging pressure TPTAGT.

At step S337, IUP
If DP <TPTAGT-P, and the actual supercharging pressure P is lower than the lower limit of the dead zone and deviates from the dead zone, the process proceeds to step S338 to increase the I component update amount DI2 to the I component update amount DI2.
PY is set and the process proceeds to step S340, where the feedback I component I2 is calculated by adding the I component update amount DI2 to the previous value I2.

In this case, in the exhaust control valve small open control mode in which the supercharging pressure is controlled by the exhaust control valve 53, the primary wastegate control mode in which the supercharging pressure is controlled by the primary wastegate valve 41 under the same single turbo is controlled. Although it is conceivable to make the gain the same, the exhaust control valve 53 is formed larger than the primary wastegate valve 41, and the exhaust control valve 53 has a larger amount of exhaust leak at the same opening. Therefore, if a control gain suitable for the supercharging pressure control of the primary wastegate valve 41 is used for the exhaust control valve 53, the control gain is too large when the exhaust control valve is opened, and hunting of the actual supercharging pressure occurs. . vice versa,
When a control gain suitable for the supercharging pressure control by the exhaust control valve 53 is used for the primary wastegate valve 41, the control gain is too small at the time of the primary wastegate control, and the followability of the actual supercharging pressure deteriorates.

For this reason, the set value K which determines the gain of the feedback P component P1 in the primary wastegate control
A set value KGP2 that determines the gain of the feedback P component P2 in the exhaust control valve small opening control, and an increase that determines the gain of the feedback I component I2 with respect to GP1, the up amount IUP1 and the down amount -IDN1 that determine the gain of the feedback I component I1. The amount of IUPY and the amount of down-IDNY are separately set, and the control gains in the primary wastegate control and the exhaust valve control valve small opening control under the same single turbo are both optimized to prevent hunting of the actual supercharging pressure. And good follow-up.

After calculating the feedback I component I2 in step S340, the flow advances to step S341 to compare the feedback I component I2 with the lower limit I2MIN.
As a result, the feedback I component I2 is reduced to the lower limit I2MIN.
In the following cases, the lower limit I2MIN is set to the feedback I component I2 in step S342, and the lower limit is set in step S342.
At 345, the duty ratio DUTY2 is calculated by adding the feedback P component P2 and the feedback I component I2 to the basic control duty DUTY2B.

The feedback I component I2 is equal to the lower limit I
If it is larger than 2MIN, the process proceeds from step S341 to step S343, and the feedback I component I2 is compared with the upper limit I2MAX. Then, the feedback I component I2 is equal to or less than the upper limit value I2MAX, and the lower limit value I2MIN.
If the value falls within the range between the upper limit value I2MAX and the upper limit value I2MAX, the process directly jumps to step S345 to add the feedback P component P2 and the feedback I component I2 to the basic control duty DUTY2B, and the duty ratio DUTY2
Is calculated.

Also, the feedback I component I2 is equal to the upper limit I
If it exceeds 2MAX, the upper limit value of the feedback I component I2 is set as the upper limit value I2MAX in step S344, and the process proceeds to step S345 to execute the basic control duty D.
The duty ratio DUTY2 is calculated by adding the feedback P component P2 and the feedback I component I2 to UTY2B.

Thereafter, the flow advances to step S346 to set the duty ratio DUTY2 to the lower limit value DU2MN2 (for example, 47
%). Here, when the duty ratio DUTY2 becomes equal to or lower than the lower limit value DU2MN2, the opening degree of the exhaust control valve becomes very large, and the supercharging pressure control by the exhaust control valve 53 becomes substantially impossible. Therefore, if DUTY2 ≦ DU2MN2, the process proceeds to step S347 and the duty ratio DUT
Y2 is fixed to the lower limit value DU2MN2, and step S351
The duty ratio DUTY2 is controlled by the exhaust control valve small opening control duty solenoid valve D. SOL. 2 is set as the duty ratio of the control signal for 2.

The duty ratio DUTY2 is set to the lower limit value D.
When it is larger than U2MN2, the process proceeds from step S346 to step S348, and the upper limit value TDU2MX is set by referring to the table with interpolation calculation based on the engine speed N. Here, if the duty ratio DUTY2 becomes too large, the opening degree of the exhaust control valve becomes very small and the preliminary rotation becomes impossible. For this reason, the exhaust control valve opening which can be pre-rotated within the range where the exhaust control valve 53 does not chatter is set to the upper limit T.
Set as DU2MX. Further, the higher the engine speed N, the higher the actual supercharging pressure P, and the control pressure of the exhaust control valve actuating actuator 54 changes so as to increase at the same duty ratio. The upper limit value TDU2MX is set in an increasing function.

Then, in step S349, the duty ratio DUTY2 is compared with the upper limit value TDU2MX, and DUTY2
If ≧ TDU2MX, the routine proceeds to step S350, where the duty ratio DUTY2 is limited to an upper limit TDU2MX, and the duty ratio DUTY2 is set to an exhaust control valve small open control duty solenoid valve D.D. in step S351. SOL.
2 is set as the duty ratio of the control signal for 2.
Also, in step S349, DUTY2 <TDU2
In the case of MX, steps S349 to S35
1 and the duty ratio DUTY2 calculated in step S345 is used as it is, and the exhaust control valve small opening control duty solenoid valve D.D. SOL. 2 is set as the duty ratio of the control signal for 2.

Accordingly, in the exhaust control valve small opening control mode,
The exhaust control valve 53 is opened slightly and the secondary turbocharger 50
Is pre-rotated. Further, the exhaust control valve small opening control duty solenoid valve D. SOL. Duty ratio DUTY of 2
2 is set by PI control, the opening of the exhaust control valve 53 is changed, or the upper limit value TDU2MX or the lower limit value DU2MN
2 and the boost pressure feedback control is performed by the exhaust control valve 53.

As described above, when switching from the primary wastegate control mode to the exhaust control valve small opening control mode, first, the exhaust control valve 53 is open-loop controlled, and the primary wastegate valve 41 is used to perform supercharging pressure feedback control. Next, the primary wastegate valve 41 is gradually fully closed, and the supercharging pressure feedback control is performed by the exhaust control valve 53, thereby preventing the fluctuation of the actual supercharging pressure and improving the operability. Connection is made smoothly. The switching state of the control mode is shown in the time chart of FIG.

Next, control when returning to the primary wastegate control mode from the exhaust control valve small opening control mode when switching the supercharging pressure control mode under the single turbo state will be described.

In this case, if the initial value setting flag FINI1 at the time of transition to the primary wastegate control mode is set in step S169 of the supercharging pressure control routine (FINI1 = 1), one of the conditions in steps S165 to S167 is satisfied. When the primary wastegate control mode is determined by the establishment, the process jumps to step S170 to clear the supercharging pressure control mode determination flag F2, and sets the initial value setting flag FINI2 at the time of transition to the exhaust control valve small opening control mode in step S171. Later, step S17
Then, the process proceeds to Step S173 via Step 2.

Therefore, FRUN = 0, F2 = 0, FIN
Steps S173 to S17 based on I1 = 1
The process proceeds to step S176 via steps S4 and S175, and the special state determination time control determination flag FREG is referred to. And
In the special state of FREG = 1, the process jumps to step S179, and in the normal state of FREG = 0, step S17.
Then, the process proceeds to step S7, where the initial value TSTDT1 of the duty ratio DUTY1 is set by referring to the table with interpolation calculation based on the intake pipe pressure (actual supercharging pressure) P.

Thereafter, in step S178, the initial value TSTDT1 is set to the duty ratio DUTY1, and in step S179, the duty ratio DUTY2 is set to 0% in order to shift to the primary wastegate control mode. The value setting flag FINI1 is cleared, and the process proceeds to step S181. Then, steps S184 and S18
5, the duty ratios DUTY1 and DUTY2 are respectively set to the primary wastegate control duty solenoid valve D. SOL. 1. Exhaust control valve small opening control duty solenoid valve SOL. 2 is set as the duty ratio of the control signal for 2.

At this time, in the turbo switching control routine,
When F2 = 0, the first exhaust control valve switching solenoid valve SO
L. 3 is turned off (step S22). DUT
In the Y1 calculation routine, the process proceeds from step S201 to steps S203 and S204, and the duty ratio DU is returned again.
TY1 is set by PI control, and the boost pressure feedback control is appropriately performed by the primary wastegate valve 41.

When the boost pressure feedback control by the primary wastegate valve 41 is started by simply setting the duty ratio DUTY1 by the PI control without giving the initial value TSTDT1, the duty ratio DUTY1 set by the P and I components is set. Since the rate of change is small, it takes time until the primary boost gate valve 41 is opened from the state where the primary wastegate valve 41 is closed with the duty ratio DUTY1 at the upper limit value DUMAX, and the actual boost pressure converges to the target boost pressure. During this time, the followability of the actual supercharging pressure to the target supercharging pressure is deteriorated, and the supercharging pressure fluctuates to deteriorate the drivability. At this point, by setting the initial value TSTDT1 at the time of switching the control mode as described above, the primary wastegate valve 41 is quickly opened, and the followability of the actual supercharging pressure P to the target supercharging pressure TPTAGT is improved. improves.

The first exhaust control valve switching solenoid valve SOL. An orifice 67 is provided in the control pressure passage 73a of the positive pressure chamber 54a of the actuator 3 and the exhaust control valve actuation actuator 54. For example, when switching from a single turbo to a twin turbo, a positive control pressure is smoothly supplied to reduce torque shock and the like. Although suppressed, the orifice 67 also has an effect when the control pressure leaks when switching from the exhaust control valve small opening control mode to the primary wastegate control mode.

At this point, as described above, the first exhaust control valve switching solenoid valve SOL. In synchronization with 3 being turned off,
The duty ratio DUTY2 is set to 0% and the exhaust control valve small opening control duty solenoid valve D. SOL. 2 is immediately closed, so that the exhaust control valve actuating actuator 54
Is controlled by a switching solenoid valve S via an orifice 67.
OL. Leaks gradually from the atmospheric port of # 3. Therefore, the exhaust control valve 53 is also gradually closed, and a part of the exhaust gas is released by the exhaust control valve 53 until the primary wastegate valve 41 is opened to an opening degree sufficient for controlling the supercharging pressure. Therefore, a temporary increase in the supercharging pressure at the time of switching is prevented, the fluctuation of the supercharging pressure accompanying the switching of the supercharging pressure control mode is suppressed, the operability is improved, and the connection of the supercharging pressure is performed smoothly. .

Initial value TSTD of duty ratio DUTY1
T1 is set to a smaller value as the intake pipe pressure P is higher as shown in FIG. 40, so that the primary wastegate valve 41 is easily opened, and the boost pressure is temporarily increased when the boost pressure control mode is switched. Effectively prevent. The switching state of this control mode is shown in the time chart of FIG.

Next, as control at the time of switching from the single turbo to the twin turbo, control at the time of switching from the primary wastegate control mode under the single turbo state to the twin turbo state without passing through the exhaust control valve small opening region. explain.

In the primary wastegate control mode, all the switching solenoid valves SOL. 1-4 are OFF. Then, when passing through the single-to-twin switching determination line L2 at the time of switching the control mode, first, the switching solenoid valve SOL. 1 and the first exhaust control valve switching solenoid valve SOL, 3 become 0 N, and then the second exhaust control valve switching solenoid valve SOL. 4 is turned on, and further, the switching solenoid valve SOL, 2 for the intake control valve is turned on so that the switching is completed. In the primary wastegate control mode, the exhaust control valve small-open control duty solenoid valve D.D. SOL. 2 is 0% non-control, and the primary wastegate control duty solenoid valve D.D. SOL. Duty ratio D of 1
UTY1 is set by PI control, and the boost pressure feedback control is performed by the primary wastegate valve 41.

Therefore, in the supercharging pressure control routine, the process proceeds from step S130 to step S131, and the switching solenoid valve SOL. 2 before the end of the OFF switching, the process proceeds to step S132, passes through the single-to-twin switching determination line L2, and the boost solenoid valve switching solenoid valve SOL. 1 is turned on. At this time, the first exhaust control valve switching solenoid valve SOL. 3 at the same time to start the switching control, the process proceeds to step S133, and the second exhaust control valve switching solenoid valve SOL. Reference is made to the ON / OFF state of No. 4. Then, the second exhaust control valve switching solenoid valve SOL. Before the exhaust control valve 53 is fully opened and the exhaust control valve 53 is turned off, the process proceeds to step S134, and the single-to-twin initial value setting flag FTWIN is referred to. Here, since the single-to-twin initial value setting flag FTWIN has already been set in step S146, the process proceeds from step S134 to step S135 to refer to the supercharging pressure control mode determination flag F2.

Since F2 = 0, step S1 is executed.
Proceeding to 36, an initial value TDU2MX is set by referring to the table with interpolation calculation based on the engine speed N. After that, in step S137, the initial value TDU2MX is set to the duty ratio DUTY2, and in step S138, the single to twin initial value setting flag FTWIN is cleared.
In step S139, the switching operation execution flag FRU is set.
Set N.

Thereafter, the process proceeds to step S140, and from step S140, the process proceeds to step S162 through steps S147, S160, and S161 according to FSING = 0, F1 = 0, and F2 = 0, and the exhaust control valve is determined by the condition determination in steps S162 to S164. Out of the small opening control region, the process goes through steps S170 to S172 and goes to step S173.
Exit. Then, at step S17, FRUN = 1 is set.
3 jumps to step S180, and furthermore, in the normal state of step FREG = 0, jumps from step S181 to step S184, giving priority to the calculation result at the time of switching, and in step S185, controls the duty ratio DUTY2 to open the exhaust control valve slightly. D. Duty solenoid valve SOL.
2 is set as the duty ratio of the control signal for 2.

After the initialization, the FTWIN =
The process proceeds from step S134 to step S151 based on 0 to check whether the duty ratio DUTY2 is 0%. If DUTY2> 0, the process proceeds to step S152 to set the duty ratio DUTY2 to the set value DDTY (for example, 1.6). %) And the process of proceeding to step S139 described above is repeated, and the duty ratio DUTY2 is reduced by the set value DDTY for each calculation cycle.

Thus, at the time of switching, the duty ratio DUT
Y2 is set to an initial value TDU2MX once as shown by a solid line in FIG.
, And then performs open loop control so as to gradually decrease. When DUTY2 = 0, the process proceeds from step S151 to step S10 to fix the duty ratio DUTY2 to 0%. After that, the second exhaust control valve switching solenoid valve SOL. When the valve 4 is turned on, a negative pressure is introduced into the negative pressure chamber 54b of the exhaust control valve actuating actuator 54, and the exhaust control valve 53 increases the valve opening speed and quickly opens fully by this negative pressure assist. The process proceeds from step S133 to step S149 to set the DUTY1 initial value setting flag FFST at the time of transition to twin turbo.

On the other hand, before the duty ratio DUTY2 becomes 0%, the engine operating state passes through the primary turbo overspeed determination line L4 (see FIG. 22) and the second exhaust control valve switching solenoid valve SOL. 4 may turn ON. In this case, steps S133 to S14
In step S9, the duty ratio DUTY2 is immediately set to 0% as indicated by the broken line in FIG. 46.

Also, the switching solenoid valve SOL. 1 is turned on, and then the intake control valve switching solenoid valve SOL. 2 is turned on before the switching solenoid valve SOL. When 1 is turned off, the switching to the twin turbo is determined to be stopped in the turbo switching control routine. In this case, in the boost pressure control routine, step S
From 132, the process goes to the above-described step S146 and subsequent steps, and the calculation at the time of switching is immediately stopped.

Here, when switching from the primary wastegate control mode under the single turbo state to the twin turbo state, the duty ratio DUTY2 is 0% and the exhaust control valve small opening control duty solenoid valve D.C. SOL. 2 is in a non-control state in which the first exhaust control valve switching solenoid valve SOL. 3 OFF → ON
Then, there is the following problem.

That is, the exhaust control valve actuating actuator 5
4, the actual supercharging pressure is immediately applied to the positive pressure chamber 54a, and the exhaust control valve 53 opens in a short time from the fully closed state, so that the secondary turbocharger 50 suddenly stops operating without preliminary rotation. It operates from the state and rotates up. Therefore, the consumption of exhaust energy is increased, and in this case, the supercharging pressure is temporarily reduced to generate a torque shock. In addition, there is a possibility that the secondary turbocharger 50 itself may over-rotate due to a rapid rise in rotation. Therefore, an orifice 67 is provided in the control pressure passage 73a of the exhaust control valve actuating actuator 54 to gradually apply the control pressure, but it is not sufficient.

At this point, as described above, the switching solenoid valve SOL. 1 and the first exhaust control valve switching solenoid valve SOL. By controlling the duty ratio DUTY2 to be temporarily increased by the initial value TDU2MX in synchronization with the turning on of 3 and then gradually reduced,
The control pressure of the positive pressure chamber 54a of the exhaust control valve actuating actuator 54 is controlled by the exhaust control valve small opening control duty solenoid valve D.V. SOL. Due to 2, it leaks at first and decreases, and then gradually increases and returns.

For this reason, the exhaust control valve 53 is first opened slightly, and the preliminary rotation of the secondary turbocharger 50 is ensured. Thereafter, as the opening degree of the exhaust control valve 53 gradually increases, the rotation speed of the secondary turbocharger 50 also sequentially increases, thereby suppressing a temporary increase in exhaust energy due to the start of operation of the secondary turbocharger. Thus, the decrease in the supercharging pressure is reduced, and the occurrence of torque shock is suppressed. In addition, since the rotation speed of the secondary turbocharger 50 gradually increases, the overspeed is prevented from occurring.

When switching the control mode, the engine speed N
Is higher, the actual supercharging pressure P is higher, and the torque shock at the time of opening the exhaust control valve is larger. Therefore, the initial value TDU2MX of the duty ratio DUTY2 is set to be larger as the engine speed N is higher, as shown in FIG. SOL. 2, the control pressure leak is increased to suppress the torque shock.

Next, the intake solenoid control valve switching solenoid valve SO
L. When 2 is set to 0 N, the intake control valve 55 is opened, the secondary turbocharger 50 is substantially operated and the switching is completed, and when the state shifts to the twin turbo state, the process proceeds from step S131 to step S153 in the supercharging pressure control routine. move on. Then, in step S153, the initial value WGIFST (for example, 88%) is set to the duty ratio DUTY1, because FFST = 1, the process proceeds to step S154 with reference to the DUST1 initial value setting flag FFST at the time of transition to the twin turbo.

Thereafter, in step S155, the DUTY1 initial value setting flag FFST at the time of transition to twin turbo is cleared, and in step S156, the twin-single switching operation determination flag FSING is set.
56 through step S147 to step S173, and in step S184, the duty ratio DUTY1 is set to the primary wastegate control duty solenoid valve D.D. SOL. It is set as the duty ratio of the control signal to 1.

Here, the primary wastegate valve 41
The actual supercharging pressure P, which is feedback-controlled by the above, tends to decrease as shown in FIG. 46 with the opening of the exhaust control valve 53 at the time of the above-described switching, and therefore, the duty ratio DUT
Y1 is increased by the feedback P component P1 and the feedback I component I1, and is increased by the primary wastegate valve 4.
1 gradually decreases. When the state shifts to the twin turbo state, the target supercharging pressure TPTAGT is changed to a twin turbo target supercharging pressure map, and is temporarily reduced as shown by the one-point line in FIG. At this time, as described above, by setting the duty ratio DUTY1 to the initial value WGIFST, the followability of the actual supercharging pressure P to the target supercharging pressure TPTAGT is improved. The switching state of the control mode is shown in the time chart of FIG.

Next, as control at the time of switching from single turbo to twin turbo, control at the time of switching from the exhaust control valve small opening control mode under the single turbo state to the twin turbo state will be described.

In the exhaust control valve small opening control mode, the first
Switching solenoid valve SOL. 3 is ON, and when passing through the single-to-twin switching determination line L2, the switching solenoid valve SOL. 1 is 0
N, and then the second exhaust control valve switching solenoid valve SO
L. 4 is turned on, and the switching solenoid valve S for the intake control valve is further turned on.
OL. 2 is turned on and the switching is completed. In the exhaust control valve small opening control mode, the duty ratio DUT
Y1 is set to the upper limit value DUMAX, and the exhaust control valve small opening control duty solenoid valve D.Y. SOL. DUTY2 of 2
Is set by the PI control, and the supercharging pressure feedback control is performed by the exhaust control valve 53.

Therefore, in the supercharging pressure control routine, the process proceeds from step S130 to step S131, and the switching solenoid valve SOL. 2 before the end of the OFF switching, the process proceeds to step S132, passes through the single-to-twin switching determination line L2, and the boost solenoid valve switching solenoid valve SOL. 1 is turned on to start the switching control, the process proceeds to step S133, and the second exhaust control valve switching solenoid valve SOL. Before 4 is turned off and the exhaust control valve 53 is fully opened, the process proceeds to step S134.

Here, since the single-to-twin-time initial value setting flag FTWIN has already been set (step S146), the process proceeds from step S134 to step S135, and since F2 = 1 in the exhaust control valve small opening control mode, the process proceeds to step S135. Jump to S138 to clear single-to-twin initial value setting flag FTWIN, and then to step S13.
In step 9, the in-operation calculation execution flag FRUN is set.

Then, in the same manner as described above, the process exits from step S140 to step S173, jumps from step S173 to step S180 when FRRUN = 1, and gives priority to the switching operation result, and in step S185, the exhaust control valve small opening control duty solenoid valve D. SOL. The duty ratio DUTY2 of 2 remains at the value immediately before switching.

Thereafter, the flow advances from step S134 to step S151 according to FTWIN = 0, and DUTY2> 0
If so, the process proceeds to step S152, where the DUT immediately before switching
Y2 is set value DDTY (eg, 1.6%) for each calculation cycle
Decrease by one. When DUTY2 = 0, the process proceeds from step S151 to step S150 to fix the duty ratio DUTY2 to 0%. Further, the second exhaust control valve switching solenoid valve SOL. 4 is turned on and the exhaust control valve 53 is fully opened, from step S133 to step S
Proceeding to 149, a DUTY1 initial value setting flag FFST at the time of transition to twin turbo is set. Thus, the open-loop control is performed such that the duty ratio DUTY2 is gradually reduced from the value immediately before the switching as shown by the solid line in FIG. 47 at the time of the switching.

At this time, the duty ratio DUTY2 is 0%
Before reaching the second exhaust control valve switching solenoid valve SO through the primary turbo overspeed determination line L4.
L. 4 is turned on, Steps S133 to S133 are performed.
In step S149, the duty ratio DUTY2 is set to 0% as indicated by the broken line in FIG.
And

When switching from the exhaust control valve small opening control mode to the twin turbo state, the exhaust control valve small opening control duty solenoid valve D.D. SOL. Duty ratio D of 2
Although the supercharging pressure is controlled by UTY2, if the duty ratio DUTY2 is immediately set to 0% from this state, the following problem occurs. That is, when the duty ratio DUTY2 is set to 0%, the positive pressure chamber 54 of the exhaust control valve actuating actuator 54 is operated.
a, the exhaust control valve small opening control duty solenoid valve D.
SOL. 2, the actual supercharging pressure is applied immediately, and the exhaust control valve 53 opens in a short time from the small open state. For this reason, the rotation speed of the secondary turbocharger 50 sharply increases, causing torque shock and excessive rotation of the secondary turbocharger 50 as described above.

At this point, as described above, the switching solenoid valve SOL. By controlling DUTY2 to gradually decrease from the value immediately before DUTY2 in synchronization with ON of the exhaust control valve 1, the exhaust control valve actuating actuator 54
The control pressure of the positive pressure chamber 54a gradually increases, and the exhaust control valve 53 opens smoothly from the small open state. Therefore, the rotation speed of the secondary turbocharger 50 is smoothly increased from the preliminary rotation state, so that the occurrence of the torque shock is suppressed and the excessive rotation is prevented beforehand.

Also, in this case, the switching solenoid valve SOL. 2 is turned on, the intake control valve 55 is opened, the secondary turbocharger 50 is substantially operated, the switching is completed, and a transition is made to the twin turbo state.
From 131, the process proceeds to step S153. And FFST
Since = 1, the process proceeds to step S154, and the duty ratio DUTY1 is set to an initial value WGIFST (eg, 88%). After that, in step S155, the DUTY1 initial value setting flag FFST at the time of transition to the twin turbo is cleared,
In step S156, an operation determination flag FSING at the time of switching from twin to single is set.

Here, the actual supercharging pressure P, which is feedback-controlled by the exhaust control valve 53, tends to decrease as shown in FIG. 47 as the exhaust control valve 53 is fully opened at the time of the above switching. When the state shifts to the twin turbo state, the target supercharging pressure TPTAGT is changed to the twin turbo target supercharging pressure map, and is temporarily reduced as shown by the one-point line in FIG. At this time, as described above, the duty ratio DUTY
By setting 1 to the initial value WGIFST, the followability of the actual boost pressure P to the target boost pressure TPTAGT is improved.
The switching state of this control mode is shown in the time chart of FIG.

Next, the boost pressure feedback control in the primary wastegate control mode under the twin turbo state will be described.

In this control mode, the duty ratio DUTY1 is set to the initial value WGIFS in the supercharging pressure control routine.
After T is set (step S154), the DUTY1 initial value setting flag FFST at the time of transition to twin turbo is set to FFS.
Since T = 0 has been cleared, step S153 is executed.
From step S156. Further, since the twin turbo discrimination flag F1 is set to F1 = 1, the process jumps from step S160 to step S170, clears the supercharging pressure control mode discrimination flag F2, and cancels the discrimination of the exhaust control valve small opening control area. I do.

In the DUTY1 calculation routine, reference results F, the supercharging pressure control mode determination flag F2, and the twin turbo determination flag F1 in steps S200, S201, and S202 are referred to as F and F.
According to REG = 0, F2 = 0, and F1 = 1, step S2
From 00, the process proceeds to step S230 via steps S201 and S203, where the twin turbo target supercharging pressure map is referenced with interpolation calculation based on the engine speed N and the throttle opening TH, and the twin turbo at standard atmospheric pressure is used. The basic target boost pressure TPTAGTM in the state is set.

[0355] The twin turbo target boost pressure map is used to set a target boost pressure for the boost pressure control on the assumption that high-octane gasoline is used and the engine warm-up is completed in the twin turbo state under the standard atmospheric pressure. The optimum value obtained by simulation or experiment is stored in advance using the engine speed N and the throttle opening TH as parameters, and the engine speed N is high and the throttle opening TH is The larger the value is, the higher the target boost pressure is.

Next, the routine proceeds to step S231, where the basic target supercharging pressure TPTAGTM corresponding to the standard atmospheric pressure is set to the atmospheric pressure AL.
Based on the atmospheric pressure (absolute pressure) ALT detected by the absolute pressure sensor 81, a supercharging atmospheric pressure correction coefficient KALCOM for performing a decrease correction with a decrease in T is expressed by a linear function expression based on the atmospheric pressure ALT shown below. Set. KALCOM ← KALC12 × ALT−KALC02 (4) where KALC12 and KALC02 are constants

The supercharging atmospheric pressure correction coefficient KALCOM according to the equation (4) under the twin turbo condition is calculated by using a constant KALC12 for giving the gradient of the supercharging atmospheric pressure correction coefficient KALCOM and a constant KALC02 for giving the intercept. Supercharging atmospheric pressure correction coefficient KALCO0 by equation (2)
As shown by the broken line in FIG. 36, M is set to be slightly larger than the supercharging atmospheric pressure correction coefficient KALCOM in the single turbo state. That is, each constant KALC12, K
ALC02 is a supercharging atmospheric pressure correction coefficient KALCOM = 1.0 corresponding to a state without correction when the atmospheric pressure ALT is the standard atmospheric pressure, and the supercharging atmospheric pressure correction coefficient is set as the atmospheric pressure ALT decreases. KALCOM is reduced, for example, when ALT = 400 mmHg, KALCOM =
It is set to a value that gives 0.73.

In steps S232 to S235, similarly to the case of the single turbo, in order to avoid overcorrection of the supercharging pressure by using the supercharging atmospheric pressure correction coefficient KALCOM calculated by the equation (4) as it is, The supercharging atmospheric pressure correction coefficient KALCOM is set to 1.0 corresponding to the upper limit and the lower limit ALCOMMIN2 (for example, ALT =
Upper and lower limits are set between 0.73) corresponding to 400 mmHg.

[0359] Thereafter, the flow proceeds to step S236, in which the basic target supercharging pressure TPTAGTM is premised on completion of engine warm-up.
Of the coolant temperature TW detected by the coolant temperature sensor 83 is set by a linear function equation based on the coolant temperature TW shown below based on the coolant temperature TW detected by the coolant temperature sensor 83. I do. KTWCOM ← KTW12 × TW−KTW02 (5) where KTW12 and KTW02 are constants

The water temperature correction coefficient KTWCOM according to the equation (5) under the twin turbo condition is calculated by using the water temperature correction coefficient KTWCOM.
KTW12 which gives the slope of the constant, KT which gives the intercept
With W02, the water temperature correction coefficient KTWC in the single turbo state is different from the water temperature correction coefficient KTWCOM in the single turbo state as shown by the broken line in FIG.
It is set slightly larger than OM. That is, each constant K
TW12 and KTW02 are values for setting the water temperature correction coefficient KTWCOM to KTWCOM = 1.0 corresponding to a state without correction when the cooling water temperature TW is the warm-up completion temperature, and decreasing the water temperature correction coefficient KTWCOM with a decrease in the cooling water temperature TW. Is set to

Next, in steps S237 to S240, as in the case of the angle turbo, the water temperature correction coefficient KTWCOM is used in order to avoid overcorrection of the supercharging pressure by using the water temperature correction coefficient KTWCOM calculated by the equation (5) as it is. Is regulated between the upper limit 1.0 and the lower limit TWCOMMIN2 corresponding to the state without correction.

[0362] Then, in step S241, the transmission 15
The gear position correction coefficient IGP for decreasing and correcting the basic target supercharging pressure TPTAGTM in accordance with the gear position of 0 is set to 1.0 corresponding to the value without correction, and step S245 is performed.
Then, the basic target supercharging pressure TPTAGTM is multiplied by a supercharging atmospheric pressure correction coefficient KALCOM, a water temperature correction coefficient KTWCOM, and a gear position correction coefficient KGP to obtain a target supercharging pressure TPT.
When the AGT is calculated, in step S250 referring to the twin turbo discrimination flag F1, F1 = 1 is set in step S2.
52, the twin turbo basic control duty map MP based on the engine speed N and the throttle opening TH.
The basic control duty DUTY1B in the twin turbo state is set by referring to the DTY12 with interpolation calculation.

[0363] The twin turbo basic control duty map MPDTY12 indicates an appropriate primary wastegate control duty for changing the opening of the primary wastegate valve 41 to obtain the target supercharging pressure during the twin turbo operation under the standard atmospheric pressure. Solenoid valve D. SOL. The basic value of the duty ratio DUTY1 for 1 is obtained in advance by simulation or experiment using the engine speed N and the throttle opening TH as parameters and stored as a map.

Then, at step S253, target boost pressure T
PTAGT and set value FBTGT (for example, 400 mmH
g), and when TPTAGT <FBTGT,
In steps S254 and S255, the feedback P
1, the feedback I component I1 is set to 0, and the opening degree of the primary wastegate valve 41 is controlled by open loop control based on the basic control duty DUTY1B.

When TPTAGT ≧ FBTGT, the twin turbo discrimination flag F1 is set in step S253.
The process proceeds to step S258 through F1 = 1 via step S256, and the twin turbo is set to the set value KGP1 for setting the feedback P component P1 according to the deviation between the target supercharging pressure TPTAGT and the actual supercharging pressure P. The set value KGP12 at the time is set, and in step S259, a deviation (TPTAGT-) between the target supercharging pressure TPTAGT and the actual supercharging pressure P is set.
P) is multiplied by a set value KGP1 to obtain a feedback P component P
When 1 is set, the upper and lower limits of the feedback P component P1 are regulated in steps S260 to S263.

Then, in step S264, the difference between the target supercharging pressure TPTAGT and the actual supercharging pressure P (TPTAGT-P)
Is compared with a set value IDNDP which defines the upper limit of the control dead zone. As a result, when the actual supercharging pressure P exceeds the upper limit of the control dead zone with respect to the target supercharging pressure TPTAGT (TPTAG)
T−P <IDNDP), the result of referring to the twin turbo discrimination flag F1 in step S265, F1 = 1, the process proceeds to step S267, and the I-component update amount DI1 is set to the twin turbo down amount −IDN2, and in step S273. The feedback I component I1 is calculated.

When the actual supercharging pressure P falls and becomes lower than the upper limit of the dead zone (TPTAGT-P ≧ IDND
P), In step S268, the difference (TPTAGT-P) between the target boost pressure TPTAGT and the actual boost pressure P is compared with a set value IUPDP that defines the lower limit of the control dead zone. And I
If UPDP≥TPTAGT-P, and the actual supercharging pressure P is within the dead zone (between the upper and lower limits), the I component update amount DI1 is set to 0 in step S269, and step S27 is performed.
Jump to 3. And IUPDP <TPTAGT
−P, and when the actual supercharging pressure P is lower than the lower limit of the dead zone and deviates from the dead zone, the result of referring to the twin turbo discrimination flag F1 in step S270 indicates that F1 = 1, the process proceeds to step S272, and the I minute Step S27 sets the up amount IUP2 during twin turbo to the update amount DI1.
Then, the process proceeds to 3 to calculate a feedback I component I1.

Here, at the time of twin turbo, the supercharging pressure of both the primary and secondary turbochargers 40 and 50 is controlled by the single primary wastegate valve 41, and the turbocharger at the time of the twin turbo is compared with the single turbo. Has a large turbo capacity, so feedback P during twin turbo
The set value KGP12 that determines the gain of the minute P1 is set to a value larger than the set value KGP11 that determines the gain of the feedback P minute P1 in the single turbo, and the down amount -ID of the feedback I minute I1 in the twin turbo.
N2, the up amount IUP2, are the down amount -IDN1, the up amount IU of the feedback I component I1 at the time of the single turbo.
Each value is set larger than P1. As a result, the control gain under the twin turbo is optimized to prevent hunting of the actual supercharging pressure, and P
The amount of feedback correction based on the I and I components is increased to improve the followability of the actual boost pressure to the target boost pressure.

At steps S274 to S277, the feedback I component I1 is set to the upper limit I1MAX and the lower limit I1.
Upper and lower limits are set between MIN and MIN. In step S278,
The supercharging pressure is controlled by setting the duty ratio DUTY1 by adding the feedback P component P1 and the feedback I component I1 to the basic control duty DUTY1B.

In the twin turbo state where the primary turbocharger 40 and the secondary turbocharger 50 operate, the primary wastegate control duty solenoid valve D.D. SOL. Duty ratio DUTY for 1
In step 1, only the opening degree of the primary wastegate valve 41 is changed, and feedback control is performed so that the actual supercharging pressure P follows the target supercharging pressure TPTAGT.

In this case, the target supercharging pressure TPTAGT is set to a high constant value after temporarily decreasing after the end of the control mode switching. For this reason, the duty ratio DUTY1 becomes a large value, and the opening degree of the primary wastegate valve 41 becomes extremely small, so that there is a possibility that the control becomes impossible. Therefore, actually, step S2 of the DUTY1 calculation routine is performed.
84 to 286, the duty ratio DUTY1 is set to an upper limit value DUMAX1 based on the engine speed N and the throttle opening TH.
And the actual supercharging pressure P is controlled to a high constant value.

Next, as control at the time of switching from twin turbo to single turbo, supercharging pressure control when switching from the twin turbo state to the primary wastegate control mode under the single turbo state will be described.

In the twin turbo state, all the switching solenoid valves SOL. 1 to 4 are ON, and all the switching solenoid valves SOL. Control is performed so that 1 to 4 are simultaneously turned off. In the twin turbo state, DUTY1 =
When DUMAX1 and DUTY2 = 0, the boost pressure feedback control is performed.

Therefore, in the supercharging pressure control routine, the supercharged pressure relief valve switching solenoid valve SOL. 1 and the switching solenoid valve SOL. When the switching is completed by turning OFF the step S2, steps S130 to S131 are performed.
The process proceeds to step S146 via 132, and a single to twin initial value setting flag FTWIN is set.

[0375] Thereafter, from step S146 to step S146
Proceeding to 140, the twin-single switching operation determination flag FSING has already been set (step S156), so the flow advances to step S141 to refer to the supercharging pressure control mode determination flag F2.
Proceeding to 142, count value CSING is set to set value TDU2
FX (for example, 2 sec). And CSIN
If G <TDU2FX, the count value CSING is counted up in step S143, and step S144 is performed.
To the duty ratio DUTY2 with a fixed value DU2FIX (10
0%) is set, and in step S145, the switching-time operation execution flag FRRUN is set.

[0376] Thereafter, from step S145 to step S
Proceeding to 160, exiting to step S173, FRUN = 1
In step S173, the process jumps from step S173 to step S180 to give priority to the operation result at the time of switching, and step S185
The duty ratio DUTY2 of the fixed value DU2FIX is changed to the exhaust control valve small opening control duty solenoid valve D. SOL. 2
Is set as the duty ratio of the control signal for.

When CSING ≧ TDU2FX, the switching calculation execution flag F is set in step S130.
RUN is cleared, and steps S131, S132, S
The process proceeds from step S142 to step S148 via 146, S140, and S141 to clear the operation determination flag FSING at the time of switching from twin to single, and then proceeds to step S1.
At 47, the count value CSING is also cleared, and step S1 is performed.
Proceed to 60.

At the time of switching the control mode, the process proceeds from step S160 to step S161 due to F1 = 0. If it is determined that the wastegate control mode is determined by the condition determination of steps S162 to 164, step S170 is performed.
To clear the supercharging pressure control mode determination flag F2,
The process proceeds to step S173 via steps S170 and S171. Then, the process proceeds from step S173 to steps S174 to S178 according to FRUN = 0, and then proceeds to step S179.
Then, the duty ratio DUTY2 is set to 0%. Immediately after the switching, open-loop control is performed so that the duty ratio DUTY2 is temporarily fixed at 100% for the set time.

Here, at the time of switching from the single turbo to the twin turbo, the exhaust control valve 53 is used to suppress the torque shock caused by the rapid rise of the rotation of the secondary turbocharger 50 and to prevent the secondary turbocharger from over-rotating. Need to be gradually opened. Therefore, the first exhaust control valve switching solenoid valve SOL. 3 and a control pressure passage 73a communicating the positive pressure chamber 54a of the exhaust control valve actuating actuator 54.
Is provided with an orifice 67 to gradually increase the control pressure. Therefore, conversely, at the time of switching from twin turbo to single turbo, the first exhaust control valve switching solenoid valve SO
L. 3 turns OFF and the exhaust control valve actuating actuator 5
When the control pressure of 4 is leaked, the reduction of the control pressure is restricted by the orifice 67 of the control pressure passage 73a, and the exhaust control valve 53 does not easily close.

Therefore, the exhaust control valve 53 continues to open despite the intake control valve 55 being closed, and the rotation of the secondary turbocharger 50 continues. The pressure between the valve 55 and the valve 55 increases, and the secondary turbocharger 50 may be damaged by surging. In this case, the supercharging pressure relief valve 57 is opened, and the capacity of the valve 57 is set sufficiently to relieve the supercharging pressure during the preliminary rotation of the secondary turbocharger 50 due to the small opening of the exhaust control valve. . For this reason,
As described above, when the degree of opening of the exhaust control valve 53 is large and the secondary turbocharger 50 is in full operation, the supercharging pressure cannot be reliably relieved by the supercharging pressure relief valve 57.

At this point, as described above, immediately after the end of the switching, the duty ratio DUTY2 is set to 1 for the set time TDU2FX.
By setting the fixed value DU2FIX to 00%, the exhaust control valve small opening control duty solenoid valve D.D. SOL. 2 is fully opened temporarily. Therefore, the control pressure of the positive pressure chamber 54a of the exhaust control valve actuating actuator 54 is controlled by the exhaust control valve small opening control duty solenoid valve D. SOL. 2, it is possible to immediately leak and decrease, and the closing of the exhaust control valve 53 is promoted. For this reason, the exhaust control valve 53 closes almost simultaneously with the intake control valve 55, thereby preventing the pressure increase of the secondary turbocharger 50 downstream of the compressor and preventing the occurrence and damage of surging.

By the way, at the time of this control mode switching, from the step S160 to the step S1 of the supercharging pressure control routine.
61, and further proceeds from any of steps S162 to S164 to step S170, where the supercharging pressure control determination flag F
2 is cleared, but the count value C is
If the conditions of steps S162 to 164 are satisfied and the exhaust control valve small-open control mode is determined before SING reaches the set value TDU2FX, the process proceeds to step S168 to set the supercharging pressure control mode determination flag F2.

Therefore, in the case of the exhaust control valve small opening control mode, the flow proceeds from step S141 to step S148 by F2 = 1 to clear the twin-single-switching operation determination flag FSING. Thus, before the count value CSING reaches the set value TDU2FX, the control is stopped by jumping from step S140 to step S147 to clear the count value CSING.

In this case, the process proceeds from step S174 to step S186 due to F2 = 1, and proceeds to step S1.
The duty ratio DUTY2 is initialized (initial value STDT2) through the processes of 86 to 191. Thereafter, the duty ratio DUTY2 is set by PI control in a DUTY2 calculation routine, and the exhaust control valve 53 is opened slightly and its exhaust control valve is opened. The boost pressure feedback control is performed by 53. The switching state of the control mode is shown in the time chart of FIG.

[0385]

As described above, according to the first aspect of the present invention, when it is determined that the vehicle speed is lower than the set value and the vehicle is stopped in the single turbo state, the basic target supercharging pressure is changed. Set the gear ratio correction coefficient to correct the decrease according to the ratio, and reduce and correct the basic target supercharging pressure by the gear ratio correction coefficient. Even when depressed, the target supercharging pressure is reduced, so that excessive driving force is not applied to the transmission, and the occurrence of malfunctions in the transmission is prevented, and the durability and reliability of the transmission are improved. be able to.

In this case, according to the second aspect of the invention, the speed ratio correction coefficient is set so that the reduction correction amount for the basic target supercharging pressure increases as the speed ratio increases. In addition to the effects of the described invention, there is an effect that an appropriate target supercharging pressure can be set according to the gear ratio.

[Brief description of the drawings]

FIG. 1 is a flowchart showing jobs of a turbo switching control routine and a supercharging pressure control routine.

FIG. 2 is a flowchart of a turbo switching control routine (part 1);

FIG. 3 is a flowchart of a turbo switching control routine (part 2);

FIG. 4 is a flowchart of a turbo switching control routine (part 3);

FIG. 5 is a flowchart of a turbo switching control routine (part 4).

FIG. 6 is a flowchart of a turbo switching control routine (part 5).

FIG. 7 is a flowchart of a boost pressure control routine (part 1).

FIG. 8 is a flowchart of a boost pressure control routine (part 2);

FIG. 9 is a flowchart of a boost pressure control routine (part 3).

FIG. 10 is a flowchart of a boost pressure control routine (part 4).

FIG. 11 is a flowchart of a boost pressure control routine (part 5).

FIG. 12 is a flowchart of a boost pressure control routine (part 6).

FIG. 13 is a flowchart of a DUTY1 calculation routine (part 1).

FIG. 14 is a flowchart of a DUTY1 calculation routine (part 2);

FIG. 15 is a flowchart of a DUTY1 calculation routine (part 3);

FIG. 16 is a flowchart of a DUTY1 calculation routine (part 4).

FIG. 17 is a flowchart of a DUTY1 calculation routine (part 5).

FIG. 18 is a flowchart of a DUTY2 calculation routine (part 1).

FIG. 19 is a flowchart of a DUTY2 calculation routine (part 2).

FIG. 20 is a flowchart of a DUTY2 calculation routine (part 3).

FIG. 21 is a flowchart of a DUTY2 calculation routine (part 4).

FIG. 22 is an explanatory diagram showing each switching determination value and the relationship between a single turbo region and a twin turbo region.

FIG. 23 is an explanatory diagram showing a linear function relationship between atmospheric pressure and a single to twin atmospheric pressure correction coefficient.

FIG. 24 is an explanatory diagram of an exhaust control valve small opening control mode region.

FIG. 25 is a conceptual diagram of an exhaust control valve opening delay time setting table.

FIG. 26 is a conceptual diagram of an intake control valve opening delay time setting table.

FIG. 27 is a conceptual diagram of an intake control valve opening differential pressure setting table.

FIG. 28 is a conceptual diagram of a determination value atmospheric pressure correction coefficient table.

FIG. 29 is an explanatory diagram showing a relationship between each determination line and a primary turbo overspeed region.

FIG. 30 is an explanatory diagram showing an atmospheric pressure correction state of each determination line.

FIG. 31 is a conceptual diagram of a twin to single atmospheric pressure correction coefficient table.

FIG. 32 is a conceptual diagram of a single turbo region continuation time determination value table.

FIG. 33 is a time chart showing a switching state from a single turbo to a twin turbo.

FIG. 34 is a time chart showing a state of switching from twin turbo to single turbo.

FIG. 35 is an explanatory diagram showing output characteristics during single turbo and twin turbo.

FIG. 36 is a diagram illustrating a linear function relationship between the atmospheric pressure and a supercharging atmospheric pressure correction coefficient.

FIG. 37 is an explanatory diagram showing a linear function relationship between a cooling water temperature and a water temperature correction coefficient.

FIG. 38 is an explanatory diagram showing an example of a target supercharging pressure table.

FIG. 39 is a conceptual diagram of an initial value setting table.

FIG. 40 is a conceptual diagram of a DUTY1 initial value setting table.

FIG. 41 is a conceptual diagram of an upper limit value setting table.

FIG. 42 is an explanatory diagram of a supercharging pressure feedback control state.

FIG. 43 is an explanatory diagram showing the state of the actual supercharging pressure in the special state and the normal state.

FIG. 44 is a time chart showing a switching state from a primary wastegate control mode to an exhaust control valve small opening control mode under a single turbo state;

FIG. 45 is a time chart showing a switching state from the exhaust control valve small opening control mode to the primary wastegate control mode under the single turbo state.

FIG. 46 is a time chart showing a switching state from a single turbo primary wastegate control mode to a twin turbo.

FIG. 47 is a time chart showing a switching state of a single turbo exhaust control valve small opening control mode to a twin turbo.

FIG. 48 is a time chart showing a switching state of a control mode from twin turbo to single turbo.

FIG. 49 is an overall configuration diagram of a supercharged engine.

FIG. 50 is a circuit configuration diagram of an electronic control system.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Engine with supercharger 40 ... Primary turbocharger 50 ... Secondary turbocharger 100 ... Engine control device (basic target supercharging pressure setting means,
Gear ratio correction coefficient setting means, target supercharging pressure setting means) 150: Transmission TPTAGTM: Basic target supercharging pressure KGP: Gear position correction coefficient (speed ratio correction coefficient) TPTAGT: Target supercharging pressure

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) F02D 41/02 301 F02D 41/04 301G 41/04 301 F02B 37/00 301C F-term (reference) 3G005 DA08 EA04 EA16 EA24 EA26 FA13 GA02 GB19 GB24 GB28 GC05 GD14 GD18 GD21 GE01 GE09 JA06 JA39 JA40 JB11 JB17 3G092 AA01 AA05 AA15 AA18 BA09 BB01 DB03 DB05 DC02 DC04 DC12 DF01 DF02 DF07 DG06 DG09 EA02 EA08 EA11 EA18 EA11 EA18 EA11 HA06Z HA16X HA16Z HB01X HB01Z HB07Z HC05Z HC09X HC09Z HE01Z HE04Z HE08Z HF12Z HF21Z HF25Z HG08Z 3G093 AA05 AB02 BA06 BA08 CA10 CA11 CB01 DA01 DA05 DA06 DB06 DB11 DB23 EA14 EC01 FA07 FB04 FA01 FA01 FA01 FA08 MA18 PA07Z PA11Z PC08Z PE03Z PE08Z PF08Z

Claims (2)

[Claims] 1. A primary turbocharger and a secondary turbocharger are arranged in parallel in an intake and exhaust system of an engine, and a shift stage is automatically changed based on a shift characteristic set in advance according to an operation state. A supercharged engine having a transmission connected to an output shaft is controlled in a single turbo state in which only the primary turbocharger is supercharged when the engine is in a low engine speed range. A supercharging pressure control device for a supercharged engine that controls a supercharging pressure in a twin turbo state in which both turbochargers are supercharged, wherein a supercharging pressure is controlled in a single turbo state based on an engine operating state. Basic target supercharging pressure, and a basic target supercharging pressure setting means for setting the basic target supercharging pressure when controlling the supercharging pressure in the twin turbo state. Speed ratio correction coefficient setting means for setting a speed ratio correction coefficient for correcting the basic target supercharging pressure to decrease in accordance with the speed ratio of the transmission when it is determined that the vehicle is stopped at a speed lower than the set value; In the turbo state, the target supercharging pressure corresponding to the single turbo state is corrected by the above gear ratio correction coefficient to set the target supercharging pressure.In the twin turbo state, the basic target supercharging pressure corresponding to the twin turbo state is set. A supercharging pressure control device for an engine with a supercharger, comprising: a target supercharging pressure setting means for setting a target supercharging pressure without correction by the speed ratio correction coefficient. 2. The gear ratio correction coefficient setting means sets the gear ratio correction coefficient such that the larger the gear ratio, the greater the amount of reduction correction to the basic target supercharging pressure. Item 2. A supercharging pressure control device for an engine with a supercharger according to Item 1.