JP2001065355A - Control device for engine with supercharger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain proper running performance by suppressing control hunting by turbo supercharge operation when operation is performed of TCS control and VDC control related to vehicle behavior control. SOLUTION: When an operating condition is placed in a twin turbo mode supercharge-operating a primary/secondary turbo supercharger, whether at least one of TCS control and VDC control is in operation or not is checked (S60, S61), when the control is in operation, switching of supercharge operation to a single turbo mode from the twin turbo mode is inhibited in only the primary turbo supercharger till ending of operation of the TCS/VDC control, even in the case that an engine speed is temporarily decreased by torque down at operation time of the VDC control and brake control, switching to the single turbo mode is eliminated, and control hunting can be avoided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for a supercharged engine that inhibits switching from a twin turbo mode to a single turbo mode when a vehicle behavior control means for stabilizing the behavior of a vehicle is in operation. .

[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.

[0003] For example, Japanese Patent Application Laid-Open No. 7-34889 discloses that 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 valve is closed and the exhaust control valve is closed or slightly opened (to pre-rotate the secondary turbocharger), only the primary turbocharger is supercharged. A technique is disclosed in which both control valves are opened to perform a supercharging operation of both turbochargers to improve output performance from a low speed range to a high speed range.

As shown in FIG. 23, this type of supercharged engine has only a primary turbocharger in terms of the relationship between the shaft torque and the engine speed (the engine load is constant). In contrast to the torque curve TQ1 at the time of the single turbo in the charging operation, the torque curve TQ2 at the time of the twin turbo in which both turbochargers are supercharged becomes higher at a certain rotational speed N0 or more, and a high shaft torque can be obtained. However, in a region lower than the rotation speed N0, the operation of the secondary turbocharger causes the shaft torque during the twin turbo to be rather reduced.

Accordingly, the torque shock is reduced by switching stepwise from the single turbo mode to the twin turbo mode or from the twin turbo mode to the single turbo mode at a point C where the two torque curves coincide with each other. .

[0006] Some vehicles are equipped with vehicle behavior control means for stabilizing the behavior of the running vehicle.
As the vehicle behavior control means, for example, a VDC (Vehicle Dynamics Control) that controls the braking force of the vehicle or the output of the engine to stabilize the behavior during turning to make the understeer tendency or the oversteer tendency correspond to the steering angle.
ol), during start acceleration on a low μ road such as a snowy road, for example, based on suppression of engine output torque by fuel cut or throttle valve opening suppression, brake fluid pressure increase control, etc.
TCS (Traction Contr) which suppresses wheel spin due to excessive driving force and ensures directional stability and driving force of the vehicle
ol System) and the like, and ABS (AntilockBrake Sy) which controls wheels within a range of a predetermined target slip ratio in order to prevent skidding during braking.
stem) is known.

When the behavior of the vehicle is controlled by the vehicle behavior control means, torque is temporarily reduced and the engine speed is reduced by the brake control. Depress into the area.

At this time, if the supercharging operation is switched from the twin turbo mode to the single turbo mode, the supercharging pressure increases and the engine torque increases. Therefore, the operation region shifts from the single turbo region to the twin turbo region again. Again, the supercharging operation is switched from the single turbo mode to the twin turbo mode.

As a result, switching between the single turbo mode and the twin turbo mode is repeated, and control hunting occurs.

In order to prevent such control hunting when switching the supercharging operation, the above-mentioned Japanese Patent Application Laid-Open No. Hei 7-3488 is used.
No. 9 discloses a single to twin switching determination line for determining switching from the single turbo mode to the twin turbo mode, and conversely, a twin for determining switching from the twin turbo mode to the single turbo mode.
There is disclosed a technique in which a single switching determination line is set to a low rotation side and a hysteresis is provided for switching the supercharging operation.

[0011]

However, the twin-to-single switching determination line disclosed in the above prior art is
Since it is a predetermined constant value, it is effective as a means for preventing control hunting in normal running, but it is effective against torque reduction by vehicle behavior control means and temporary decrease in engine speed due to brake control. Can't respond.

It is also conceivable to shift the twin-to-single switching determination line when the vehicle behavior control is activated to a lower load and a lower rotation speed than usual, but the control becomes complicated. Is not preferred.

SUMMARY OF THE INVENTION In view of the above circumstances, the present invention suppresses control hunting due to turbocharging when vehicle behavior control is in operation, and provides a control device for an engine with a supercharger capable of obtaining good running performance. The purpose is to provide.

[0014]

According to a first aspect of the present invention, there is provided a turbocharger having a primary turbocharger and a secondary turbocharger. Operating region determining means for dividing into a high-speed twin-turbo region for charging operation and a single-turbo region for low-speed region for supercharging only the primary turbocharger, and determining a current operating region based on the engine operating state; After the operating region has shifted from the single turbo region to the twin turbo region side, the operating state is switched from the single turbo mode in which only the primary turbocharger is in the supercharging operation to the twin turbo mode in which both the turbocharger is in the supercharging operation, Also, after the above operating area has shifted from the twin turbo area to the single turbo area, the operating state is changed from the twin turbo mode to the single turbo mode. Switching turbo switching means, secondary turbocharger control means for controlling the operation of the secondary turbocharger according to a command from the turbo switching means, and stabilizing the behavior of the vehicle when the operation state is in the twin turbo mode. Detecting the operating state of the vehicle behavior control means to be activated, and when the vehicle behavior control means is in operation, a turbo switching operation inhibiting means for inhibiting switching from the twin turbo mode to the single turbo mode. I do.

In other words, according to the first aspect of the present invention, only the primary turbocharger is operated from the twin turbo range in a high-speed range in which the operation region supercharges the primary turbocharger and the secondary turbocharger. When the vehicle shifts to the single turbo region in the low speed range to be operated, the operation state of the vehicle behavior control means is detected. When the vehicle behavior control is in operation, switching from the twin turbo mode to the single turbo mode is prohibited. This suppresses unnecessary switching of the turbo even when the engine speed is temporarily reduced by the torque reduction and the brake control when the vehicle behavior control is operating.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. First, with reference to FIG. 20, an overall configuration of a supercharged engine to which the present invention is applied will be described.

Reference numeral 1 in FIG. 1 denotes a horizontally opposed engine (a four-cylinder engine in the present embodiment). A combustion chamber 5, an intake port 6, an exhaust port 7, and a spark plug are provided in left and right banks 3 and 4 of a crankcase 2. 8, a valve train 9 and the like. The left bank 3 has # 2 and # 4 cylinders, and the right bank 4 has # 1 and # 3 cylinders.

Due to the shortened shape of the engine, a primary turbocharger 40 and a secondary turbocharger 50 are provided immediately after the left and right banks 3 and 4, respectively.
As an exhaust system, a common exhaust pipe 10 from both the left and right banks 3, 4 is provided with turbines 40a, 5 of both turbochargers 40, 50.
0a, the exhaust pipes 11 from the turbines 40a, 50a merge into one exhaust pipe 12, and the catalytic converter 1
3. It is communicated with 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.

As an intake system, intake pipes 16 and 17 branched into two from the downstream of the air cleaner 15 are respectively connected to compressors 40b and 50b of both turbochargers 40 and 50, and intake pipes from the compressors 40b and 50b are provided. 1
8, 19 are communicated with the intercooler 20. The intercooler 20 communicates with the chamber 22 via a throttle body 27 having a throttle valve 21, and the chamber 22 communicates with the intake port 6 of each cylinder 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 valve (ISCV) 25 and a check valve 26 that opens with a negative pressure are provided to control the intake air amount during idling or deceleration.

As a fuel system, an intake manifold 23 is provided.
The injector 3 is located immediately upstream of the intake port 6 in each cylinder of
0 and a fuel tank 32 having a fuel pump 31
A fuel passage 33 is provided with a filter 34 and a fuel pressure regulator 35 and communicates with the injector 30. The fuel pressure regulator 35 regulates the fuel pressure supplied to the injector 30 at a constant level with respect to the intake pressure. Control device (E
The injector 30 is driven by the pulse width of the injection signal from the GI ECU (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.

Next, an operation system of the primary turbocharger 40 will be described. Primary turbocharger 40
Is driven to rotate the compressor 40b by the exhaust energy introduced into the turbine 40a, and inhales and pressurizes the air to operate so as to always supercharge the air. On the turbine 40a side, a primary wastegate valve 41 provided with a diaphragm type actuator 42 is provided. The pressure chamber of the actuator 42 communicates with a control pressure passage 44 having an orifice 48 from immediately downstream of the compressor 40b, and communicates so as to open the wastegate valve 41 with good response when the supercharging pressure rises above a set value. You.

The control pressure passage 44 further communicates a supercharging pressure with a duty solenoid valve D.SOL.1, which leaks to the upstream side of the compressor 40b, and a predetermined control pressure is controlled by the duty solenoid valve D.SOL.1. And acts on the actuator 42 to change the opening of the wastegate valve 41 to control the supercharging pressure. Here, the duty solenoid valve D.SO
L.1 is an engine electronic control unit (EGI E
CU) 100, and operates when the duty ratio of the duty signal is small. When the duty ratio of the duty signal is small, the opening degree of the waste gate valve 41 is increased with a high control pressure to reduce the supercharging pressure. The control pressure is reduced by the increase, the opening degree of the waste gate valve 41 is reduced, and the supercharging pressure is increased.

On the other hand, in order to prevent a decrease in compressor rotation and the occurrence 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. Secondary turbocharger 50
Similarly, the turbine 50a and the compressor 50
b is rotationally driven and supercharged, and the turbine 50a
A secondary wastegate valve 51 having an actuator 52 on the side is provided. The exhaust pipe 10 upstream of the turbine 50a has a diaphragm actuator 5
4 is provided with a downstream opening type exhaust control valve 53 provided with the same actuator 56 as the downstream side 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.

The operation system of each of these valves will be described. First, a surge tank 60 as a negative pressure source communicates with the intake manifold 23 through a passage 61 having a check valve 62 to store negative pressure and buffer pulsating pressure when the throttle valve 21 is fully closed. Further, a switching solenoid valve SOL. For the supercharging pressure relief valve for opening and closing the supercharging pressure relief valve 57. 1. Intake control valve 55
Switching solenoid valve for the intake control valve SOL. 2,
The first and second exhaust control valve switching solenoid valves SOL. 3, 4; a duty solenoid valve D.SOL.2 for small opening control of the exhaust control valve 53; and a switching solenoid valve for secondary wastegate valve SOL. W. Each switching solenoid valve SOL. W, SOL. Reference numerals 1 to 4 denote negative pressure through the negative pressure passage 63 from the surge tank 60 and an intake control valve 55 in response to an ON / OFF signal from an engine electronic control unit (EGI ECU) 100 that controls the engine operating state in a wide range. Positive pressure passages 64a, 6 communicating downstream
4b, the pressure is selected from the positive pressure or the atmospheric pressure, and is guided to the actuator side through each of the control pressure passages 70a to 74a, and the secondary wastegate valve 51, the supercharging pressure relief valve 5
7. Operate the control valves 55 and 53. The duty solenoid valve D.SOL.2 operates the positive pressure chamber 54a of the actuator 54 in response to a duty signal from the EGI ECU 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 and the positive pressure passage 64a is opened to introduce a positive pressure into the pressure chamber of the supercharging pressure relief valve 57, thereby closing 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 the secondary wastegate valve SOL. W is turned off only when the EGI ECU 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. And, the switching solenoid valve SOL. W is disposed in the actuator 52 by closing the passage 65 communicating with the upstream of the intake control valve 55 when opened and opening the atmosphere port to introduce atmospheric pressure to the actuator 52 through the control pressure passage 70a. The secondary wastegate valve 51 is closed by the biasing force of the spring. 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 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 as compared with when using high-octane gasoline.

Further, the first exhaust control valve switching solenoid valve SOL. 3 is provided in the positive pressure chamber 54a of the actuator 54 for operating the exhaust control valve 53 with the second exhaust control valve switching solenoid valve SOL. The control pressure passages 74a from the pressure chambers 4 communicate with the negative pressure chambers 54b containing the springs of the actuators 54, respectively. Then, both switching solenoid valves SOL. When both 3 and 4 are 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 closes the negative pressure passage 63 and opens the atmosphere port, whereby both chambers 54a and 54b of the actuator 54 are opened 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. . Further, both switching solenoid valves SOL. Both 3 and 4 are ON
, The atmosphere ports are closed, and the first exhaust control valve switching solenoid valve SOL. 3 opens the positive pressure passage 64b side, and the second exhaust control valve switching solenoid valve SOL. 4 opens the side of the negative pressure passage 63 to guide the positive pressure to the positive pressure chamber 54a and the negative pressure to the negative pressure chamber 54b of the actuator 54, and fully open the exhaust control valve 53 against the urging force of the spring.

First exhaust control valve switching solenoid valve SO
L. An orifice 67 is provided in the control pressure passage 73a from the exhaust passage 3, and a leak passage 66 is communicated with the downstream side of the orifice 67 and the intake pipe 16. A duty solenoid for controlling the small opening of the exhaust control valve is connected to the leak passage 66. Valve D.SOL.
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 actuator 54 and the negative pressure chamber 54b is opened to the atmosphere, and the positive pressure is leaked by the duty solenoid valve D.SOL. Small open. Here, the duty solenoid valve D.SOL.2 is connected to the EGI ECU
If the duty ratio in the duty signal from 100 is large, the positive pressure acting on the positive pressure chamber 54a is reduced due to an increase in the amount of leakage, and the opening degree of the exhaust control valve 53 is reduced. As the duty ratio decreases, the amount of leakage decreases. The exhaust pressure control valve 53 operates to increase the opening degree of the exhaust control valve 53 while maintaining the positive pressure high. Then, when the engine operation area is in the predetermined exhaust control valve small opening control mode area under the single turbo mode, the boost pressure is feedback controlled by the opening degree of the exhaust control valve 53 by the duty solenoid valve D.SOL.2, With this supercharging pressure control, the exhaust control valve 53 is slightly opened.

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 detects an intake pipe pressure (intake pressure in the intake manifold 23) and an atmospheric pressure by a switching solenoid valve 76. It is provided to select and detect.

A knock sensor 82 is mounted on the engine 1, a coolant temperature sensor 83 faces a cooling water passage communicating the left and right banks 3, 4, and an O 2 sensor 84 faces the exhaust pipe 10. Further, a throttle sensor 85 having a built-in throttle opening sensor and an idle switch for detecting the throttle fully closed is connected to the throttle valve 21, and an intake air amount sensor 8 is provided immediately downstream of the air cleaner 15.
6 are provided.

A crank rotor 90 is axially 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 camshaft in the valve train 9 has:
A cylinder angle cam angle sensor 88 composed of an electromagnetic pickup or the like is provided in opposition.

Crank angle sensor 87, cam angle sensor 88
In this case, protrusions (or slits) formed at predetermined intervals on the crank rotor 90 and the cam rotor 91 are detected with the operation of the engine, and a crank pulse and a cam pulse are output to the EGI ECU 100. And EGI ECU
In 100, the engine speed is calculated from the interval time of the crank pulse (detected protrusion), the ignition timing, the fuel injection start timing, and the like are calculated, and further, the cylinder is determined from the input pattern of the crank pulse and the cam pulse.

Next, a system configuration of the EGI ECU 100 for controlling the engine operating state over a wide range will be described with reference to FIG. EGI ECU 100 includes CPU 10
1, ROM 102, RAM 103, backup RAM
A constant voltage circuit 106 and a drive circuit 107 for supplying a predetermined stabilized power to each section are built in, mainly composed of a microcomputer in which an I / O interface 104 and an I / O interface 105 are connected via a bus line.

The constant voltage circuit 106 is connected to a battery 96 via a relay contact of an ECU relay 95, and a relay coil of the ECU relay 95 is connected to the battery 96 via an ignition switch 97. The constant voltage circuit 106 is directly connected to the battery 96, and further, the fuel pump 31 is connected via a relay contact of the fuel pump relay 98.

That is, the constant voltage circuit 106 supplies control power to each unit when the ignition switch 97 is turned on and the relay contact of the ECU relay 95 is closed, and when the ignition switch 97 is turned off. , The backup power supply to the backup RAM 104
To supply.

Various sensors 80 to 88, a vehicle speed sensor 89, and a battery 96 are connected to input ports of the I / O interface 105. The igniter 36 is connected to the output port of the I / O interface 105, and the ISCV 25,
The injector 30, each switching solenoid valve 76, SOL.
W, SOL. 1-4, duty solenoid valve D.SOL.1,
2 and the relay coil of the fuel pump relay 98 are connected. Further, an EGI ECU 100 and a VDC (Vehicle Dynamics Control) electronic control unit (VDC ECU) 110 for controlling the behavior of the vehicle are connected to each other via two interfaces so as to be capable of two-way communication.

Then, the ignition switch 97 is set to O
N, the ECU relay 95 is turned on, and the constant voltage circuit 1
06, a constant voltage is supplied to each part, and the EGI ECU
100 executes various controls.

That is, in the EGI ECU 100, the CPU 101 inputs the detection signals from the various sensors 80 to 89 via the I / O interface 105 based on the calculation program stored in the ROM 102, and stores them in the RAM 103 and the backup RAM 104. Various control amounts are calculated based on the various data stored, the fixed data stored in the ROM, and the table values. Then, the fuel pump relay 98 is turned on by the drive circuit 107.
N, the fuel pump 31 is energized and driven, and each of the switching solenoid valves 76, SOL.
W, SOL. The ON / OFF signals are output to 1-4 and the duty signals are output to the duty solenoid valves D.SOL.1 and 2 to perform turbocharger operation number switching control and supercharging pressure control.
A driving pulse width signal corresponding to the calculated fuel injection amount is output at a predetermined timing to the injector 30 of the corresponding cylinder to perform fuel injection control, and an ignition signal is output to the igniter 36 at a predetermined timing to control ignition timing. And I
A control signal is output to the SCV 25 to execute idle speed control and the like.

Further, in EGI ECU 100, VDC
The engine output is limited by controlling the number of cuts of the fuel injection cylinder in accordance with a command from the ECU 110, and the engine speed signal and the current engine output signal are converted to the VDC ECU1.
Output to 10

Here, the operation of the VDC control system for controlling the behavior of the vehicle will be briefly described with reference to FIG. The VDC ECU 110 includes a steering angle sensor 111 that detects a steering angle and a rotation direction of the steering, a front-rear G sensor 112 that detects a change in front-rear G (acceleration) that occurs when the vehicle is decelerated or accelerated, Lateral G sensor 113 that detects a change in lateral G (lateral acceleration) occurring in
A yaw rate sensor 114 for detecting a rotational angular velocity of the vehicle body about a vertical axis generated when the vehicle turns, a pressure sensor 115b for detecting a hydraulic pressure generated when a master cylinder 115a is operated via a brake pedal 115, and each wheel. Wheel speed sensor 116FR that detects the rotation speed of
Signals from 116FL, 116RR, and 116RL are input.

Reference numeral 108 denotes an automatic transmission, and 109 denotes an automatic transmission (AT) ECU, which controls the front-rear drive torque distribution optimal for the control of each of the VDC and TCS according to a command from the VDC ECU 110. V from ECU 109
The gear position information is output to DC ECU 110.

The VDC ECU 110 also has an EGI EC
A microcomputer similar to U100,
For DC control, the CPU processes each input signal according to a control program stored in the ROM in advance while using the temporary storage function of the RAM, and outputs a signal for controlling fuel injection to the EGI ECU 110, and Each of the wheel cylinders 117FR, 117FL, 11 connected to four driving wheels by driving a solenoid valve (not shown) provided in a hydraulic circuit of the hydraulic unit 120.
By switching the brake pressure supplied to 7RR and 117RL to increase, hold, and reduce pressure, the braking force of each drive wheel is controlled independently, and the behavior during turning is stabilized. In addition, VD
The vehicle behavior control by the C ECU 110 is described in detail in Japanese Patent Application Laid-Open No. H10-157589 previously submitted by the present applicant.

The TCS control is performed by the EGI ECU 100
The slip state of each drive wheel is detected based on the output value of each wheel speed sensor 116FR, 116FL, 116RR, 116RL detected by the VDC ECU 110, and the output torque of the engine is reduced by fuel cut, brake operation, etc. Ensures startability and maneuverability on low μ roads. Note that T
Regarding CS control, Japanese Unexamined Patent Publication No.
Since it has already been described in Japanese Patent Application Laid-Open No. 33809, a detailed description thereof will be omitted here. However, in this prior art, a technique is provided in which a sub-throttle valve is disposed upstream of a normal throttle valve interposed in a throttle passage, and when slippage is detected in a driving wheel, the opening degree of the sub-throttle valve is controlled. It has been disclosed.

Next, the supercharger operation number switching control by the EGI ECU 100 will be described with reference to a turbo switching control routine shown in FIGS. In this routine, after the ignition switch 97 is turned on, a set time (for example, 1)
0 msec).

When the power is supplied to the EGI ECU 100 by turning on the ignition switch 97, the system is initialized (clears each flag and each count value).
First, in step S1, the value of the twin turbo mode determination flag F1 is referred to. If the twin turbo mode discrimination flag F1 is cleared, step S2
The process proceeds to step S60 if it is set. This twin turbo mode discrimination flag F1 is cleared when the current control state is the single turbo mode in which only the primary turbocharger 40 is supercharged, and in the twin turbo mode in which both the turbochargers 40 and 50 are supercharged. Sometimes set.

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

Immediately after the ignition switch 97 is turned on and when the current control state is the single turbo mode, F
Since 1 = 0, the process proceeds to step S2.

In step S2, a single to twin switching determination basic value TP2B is set based on the engine speed N by referring to the turbo switching determination value table with interpolation calculation. The single to twin switching determination basic value TP2B is for determining switching from the single turbo mode to the twin turbo mode at the standard atmospheric pressure (760 mmHg).

As shown in FIG. 7, in the turbo switching determination value table, the single turbo mode is switched to the twin turbo mode from the relationship between the engine speed N and the engine load (in the present embodiment, the basic fuel injection pulse width) TP. Single to twin switching determination line L2, and vice versa, twin to switch from twin turbo mode to single turbo mode
The single switching determination line L1 is previously obtained from experiments or the like under standard atmospheric pressure, and a single turbo region and a twin turbo region are set. Then, each line L2, L
The basic values TP2B and TP1B for the single-to-twin switching determination and the twin-single switching determination basic value TP1B are stored in advance in a series of addresses in the ROM 102 as a table using the engine speed N as a parameter.

The turbo switching determination value table may be a free grid table (unequally spaced grid table) using the engine speed N as a parameter. By setting the turbo switching determination value table as a free grid table, even if the storage capacity is the same, the single-to-twin switching determination basic value TP2B and the twin-to-single switching determination basic value TP1B of the frequently used area are more precisely determined. Can be set,
Turbo switching timing is optimized, turbo overspeed can be prevented, and controllability is improved.

Here, the single-to-twin switching determination line L2 is connected to a line shown in FIG.
Curve of output characteristics in single turbo mode TQ
1 and the torque curve TQ2 in the twin turbo mode need to be set at a point C, and therefore, as shown in FIG.
Is set to the low load side in accordance with the rise of. Also, as shown in the figure, in order to prevent control hunting when switching the number of turbochargers operated, a twin-to-single switching determination line L1 is used.
Is set to have a relatively wide hysteresis on the low rotation speed side with respect to the single-to-twin switching determination line L2.

When the process proceeds to step S3, the single to twin atmospheric pressure correction coefficient KTWNALT when the standard atmospheric pressure (760 mmHg) is set to 1.0 is expressed by the following equation. It is calculated based on a linear equation. KTWNALT ← KALT1 × ALT + KALTO where
KALT1 is a constant that determines the slope of KTWNALT, KALTO is KTW
It is a constant that determines the initial value of NALT.

Single to twin atmospheric pressure correction coefficient KTWNALT
Is calculated from a simple linear equation to obtain the conventional atmospheric pressure A
Compared to the case where a table storing the single to twin atmospheric pressure correction coefficient KTWNALT with LT as a parameter is referred to with interpolation calculation, the amount of data to be stored is reduced, the calculation becomes easier, and the single to twin switching control is simplified. I can do it.

Thereafter, the process proceeds to step S4, where
4, S5 single to twin atmospheric pressure correction coefficient KTWNALT
Is the standard atmospheric pressure upper limit 1.0 and lower limit TWNALTM
It is checked whether it is within IN or not. If it exceeds the upper limit of 1.0 (KTWNALT> 1.0), go to step S6 and set the single to twin atmospheric pressure correction coefficient KTWNALT to the upper limit.
The value is fixed at 1.0 (KTWNALT ← 1.0), and the process proceeds to step S8. If it is less than the lower limit value TWNALTMIN, (KTWNAL
T <TWNALTMIN), the process proceeds to step S7, and the single to twin atmospheric pressure correction coefficient KTWNALT is set to the lower limit value TWNALT.
Fix at MIN (KTWNALT ← TWNALTMIN) and proceed to step S8. In this embodiment, the lower limit value TWNALTMI
N is set to 0.6, which is a value equivalent to about 500 mmHg when 760 mmHg, which is the standard atmospheric pressure, is set to 1.0. This lower limit value TWNALTMIN is set for each model with 0 being the limit value.

As a result, as shown in FIG.
The twin atmospheric pressure correction coefficient KTWNALT is 50 for the atmospheric pressure ALT.
At 0 mmHg or less, the lower limit value is fixed to TWNALTMIN, and between 500 and 760 mmHg, TWNALTMI
It changes proportionally between N and 1.0, and the atmospheric pressure ALT is 760 m
When it exceeds mHg, it is fixed at 1.0.

When the process proceeds to step S8, the single to twin switching determination basic value TP2B is corrected by the single to twin atmospheric pressure correction coefficient KTWNALT to set the single to twin switching determination value TP2.

Next, the process proceeds to step S9, where a single →
Twin switching determination value TP2 and current basic fuel injection pulse width T
P (hereinafter referred to as “engine load”). If TP <TP2, the process proceeds to step S10. If TP ≧ TP2,
The flow branches to step S30 to shift to single-to-twin switching control for switching from the single turbo mode to the twin turbo mode.

The single-to-twin switching determination value TP2 is calculated based on the atmospheric pressure AL using the single-to-twin atmospheric pressure correction coefficient KTWNALT.
The value is corrected to be smaller as T is lower. For this reason, as the atmospheric pressure ALT becomes lower, the turbochargers 40 and 50 are switched from the single turbo mode in which only the primary turbocharger 40 performs the supercharging operation according to the single-to-twin switching determination value TP2.
A single-to-twin switch determination line L2 for determining the switching of the supercharging operation to the twin-turbo mode has a low load and a low rotation speed as shown by a one-dot chain line with respect to the case of the standard atmospheric pressure shown by the solid line in FIG. Is corrected to

As a result, the timing at which the engine operation region shifts from the single turbo region to the twin turbo region at the boundary of the single-to-twin switching determination line L2 is advanced, and the transition from the single turbo mode to the single-to-twin switching control is advanced. As a result, the switching from the single turbo mode to the twin turbo mode is hastened.

When the supercharging pressure control is performed by the absolute pressure, the differential pressure between the target supercharging pressure and the atmospheric pressure becomes larger as the atmospheric pressure ALT becomes lower, such as when traveling at high altitude where the atmospheric pressure ALT is low. If pressure is to be obtained, 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 mode in which only the primary turbocharger 40 operates in supercharging, most of the exhaust gas is discharged from the primary turbocharger 4.
As the atmospheric pressure ALT is lower, the engine operating region in which the primary turbocharger 40 is in an overspeed state is expanded to a higher load and a higher speed side. As described above, this is remarkable when the primary turbocharger 40 has a low-speed small capacity.

Therefore, as the atmospheric pressure ALT is lower, the single turbo mode based on the engine operating state is changed from the single turbo mode to the single mode.
By advancing the timing of shifting to the twin switching control and the fully opening control timing of the exhaust control valve 53, which will be described later, the exhaust flow introduced into the primary turbocharger 40 by fully opening the exhaust control valve 53 is changed to the secondary turbocharger. 50 to prevent over-rotation of the primary turbocharger 40.

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 rate increase rate of the primary turbocharger 40 changes under the single turbo mode due to the atmospheric pressure fluctuation, and the operation feeling due to the start of the operation of the secondary turbocharger 50 changes.
By switching the mode to the twin turbo mode earlier as the atmospheric pressure ALT is lower, the driving feeling accompanying the start of 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.

On the other hand, if TP <TP2 in step S9 and the process proceeds to step S10, single turbo mode control is performed.

At step S10, the value of the supercharging pressure control mode determination flag F2 is referred to. This supercharging pressure control mode discrimination flag F2 indicates that the current operation area is within the exhaust control valve small opening control mode area for performing the supercharging pressure control by the small opening of the exhaust control valve 53 and for pre-rotating the secondary turbocharger 50. Is set when it is out of range, and cleared when it is out of the area.

Therefore, when the ignition switch 97 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 execution of the previous routine, F2 = 0, so that the processing proceeds to step S11, and the condition determination in steps S11 to S13 is performed. It is determined whether or not the current operation region has shifted into the exhaust control valve small opening control mode region.

The transition to the exhaust control valve small opening control mode range is determined by the single-twin switching determination line L2 based on the relationship between the engine speed N and the intake pipe pressure (supercharging pressure) P as shown in FIG. On the lower rotation speed and lower load side, that is, under the single turbo mode, the set value N2 (for example, 265
0 rpm), P2 (for example, 1120 mmHg), and the throttle opening TH is equal to the set value TH2.
If it is not less than (for example, 30 deg), it is determined that it has moved into the area.

That is, in step S11, the engine speed N is compared with the set value N2, in step S12, the intake pipe pressure P is compared with the set value P2, and in step S13, the throttle opening TH and the set value TH2 are compared. Compare. And
If N <N2, P <P2, or TH <TH2, the process proceeds to step S14, where it is determined that the current operation region is outside the exhaust control valve small opening control mode region, and the supercharging pressure control mode determination flag F2 is cleared. And N ≧ N2 and P ≧ P2
If TH ≧ TH2, the process proceeds to step S15, where it is determined that the current operation region has shifted to the exhaust control valve small opening control mode region, and the supercharging pressure control mode determination flag F2 is set.

At steps S16 and S17, the switching solenoid valve SOL. 1, the switching solenoid valve SOL. 2 are turned off. Next, the routine proceeds to step S18, in which the value of the supercharging pressure control mode determination flag F2 is referred to. If F2 = 0, the routine proceeds to step S19, and in steps S19, S20, the first exhaust control valve switching solenoid valve SOL. 3, the second exhaust control valve switching solenoid valve SOL. 4 are turned off.

Thereafter, in steps S21 to S23, the twin turbo mode 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 single turbo mode and in the low-rotation, low-load operation region outside the exhaust control valve small-open control mode region, each switching solenoid valve SOL. 1 to 4 are all turned off. Thus, 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 spring.
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 actuator 54 by turning off the switches 3 and 4, the valve is closed by the urging force of the spring.

When the exhaust control valve 53 is closed, the introduction of exhaust gas to the secondary turbocharger 50 is shut off, the secondary turbocharger 50 is deactivated, and the single turbocharger that operates only the primary turbocharger 40 is operated. Mode. Further, by closing the intake control valve 55, the leakage of the supercharging pressure from the primary turbocharger 40 to the secondary turbocharger 50 side via the intake control valve 55 is prevented,
The reduction of the supercharging pressure is prevented.

In the case of the single turbo mode and out of the exhaust control valve small opening control mode region or the twin turbo mode described later, the supercharging pressure feedback control is not described in detail here, but the primary This is performed using only the gate valve 41. The supercharging pressure control uses the absolute pressure, sets a target supercharging pressure based on the engine operating state, compares the intake pipe pressure detected by the absolute pressure sensor 81 with the actual supercharging pressure P, According to the comparison result, for example, the duty solenoid valve D. is controlled by PI control.
An ON duty (duty ratio) for SOL.1 is calculated, and a duty signal of this ON duty is output to the duty solenoid valve D.SOL.1 to control the primary wastegate valve 41.

On the other hand, if it is determined in step S15 that the current operation range is within the exhaust control valve small opening control mode range and the supercharging pressure control mode determination flag F2 is set, the process proceeds to step S24 through steps S16 to S18. To the first exhaust control valve switching solenoid valve SOL. Turn ON only 3 Therefore, the first exhaust control valve switching solenoid valve SO
L. By turning on 3, positive pressure chamber 54a of actuator 54
, And the exhaust control valve 53 is opened.

In this exhaust control valve small-opening control mode, the exhaust control valve small-opening control routine shown in FIG. 6 is executed every set time (for example, 480 msec). The supercharging pressure feedback control is performed, and accordingly, the exhaust control valve 53 is slightly opened. That is, referring to the value of the supercharging pressure control mode determination flag F2 in step S100 in FIG. 6, the routine exits when F2 = 0, and proceeds to step S101 when F2 = 1 and in the exhaust control valve small opening control mode. , A switching solenoid valve SOL. Determine the energization state for 1
SOL. If 1 = ON, the routine exits and SOL.
When 1 = OFF, the process proceeds to step S102, where the target supercharging pressure based on the absolute pressure is compared with the actual supercharging pressure P detected by the absolute pressure sensor 81, and according to the comparison result, for example, P
ON duty (duty ratio) for duty solenoid valve D.SOL.2 for exhaust control valve small opening control by I control
And outputs a duty signal of the ON duty to the duty solenoid valve D.SOL.2 to execute the supercharging pressure feedback control. Therefore, the positive pressure chamber 54a of the actuator 54 is operated by the duty solenoid valve D.SOL.2.
As shown in FIG. 18, the exhaust control valve 53 is opened slightly, and the supercharging pressure feedback control is performed using only the exhaust control valve 53, as shown in FIG. A part of the exhaust gas is supplied to the turbine 50a of the secondary turbocharger 50 by the small opening of the exhaust control valve 53, and the secondary turbocharger 50 is pre-rotated to prepare for the transition to the twin turbo mode.

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.

In the single turbo mode, if the engine operation area is within the exhaust control valve small opening control mode area and the supercharging pressure control mode discrimination flag F2 is set (F2 = 1), the routine proceeds to step S10. Then, the process proceeds to step S25, and it is determined whether or not the current operation region has shifted out of the exhaust control valve small opening control mode region based on the condition determination in steps S25 to S27.

As shown in FIG. 9, in order to prevent the control hunting at the time of switching the supercharging pressure control mode, the determination of the shift to the outside of the region is performed by setting the set value N1 lower than the set values N2, P2 and TH2 as shown in FIG. (For example, 2600 rpm), P1 (for example, 1070 mmHg), TH1 (for example, 25 de)
g). In step S25, the engine speed N is compared with the set value N1, in step S26, the intake pipe pressure (supercharging pressure) P is compared with the set value P1, and in step S27, the throttle opening TH and the set value TH1 are compared. If N <N1, P <P1, or TH <TH1, it is determined that the current operation region has shifted out of the exhaust control valve small opening control mode region, and the process proceeds to step S14 described above, where the supercharging is performed. The pressure control mode determination flag F2 is cleared. Thereby, the exhaust control valve small opening control is released. If N ≧ N1, P ≧ P1, and TH ≧ TH1, it is determined that the current operation region remains within the region, and the routine proceeds to step S15, where the supercharging pressure control mode determination flag F2 is set to F2 = 1. And the exhaust control valve small opening control is continued.

As described above, in the single turbo mode, 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, the air is supplied to each cylinder through the chamber 22 and the intake manifold 23 with high charging efficiency, and the supercharging action is performed. I do. And
In the single turbo mode in which only the primary turbocharger 40 operates in the single turbo mode, as shown in the output characteristics of FIG. 23, 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 S9, TP ≥ TP2, that is, the current operating region is the single-to-twin switching determination line L2.
If it is determined that the transition from the single turbo region to the twin turbo region (see FIG. 15) has taken place at
The control branches to 30 to execute single-to-twin switching control for switching from the single turbo mode in which only the primary turbocharger 40 operates to the twin turbo mode in which both turbochargers 40 and 50 operate.

Then, first, in 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. When 1, 3 are OFF, steps S31, S
After turning on each at 33, the process proceeds to step S34.

Therefore, the supercharging pressure relief valve 57 is provided with a switching solenoid valve SOL. By turning on 1 the positive pressure from the positive pressure passage 64a is introduced into the pressure chamber,
The valve is immediately closed by the positive pressure and the urging force of the spring. Further, the exhaust control valve 53 is provided with a first exhaust control valve switching solenoid valve SOL. Actuator 54 by turning on 3
The valve opens when a positive pressure is introduced into the positive pressure chamber 54a.
In addition, when the shift from the single control mode to the single-to-twin switching control is performed from the exhaust control valve small opening control mode under the single turbo mode,
Switching solenoid valve SOL. For boost pressure relief valve 1 ON
Thus, in the exhaust control valve small opening control routine of FIG.
Step S1 without performing the supercharging pressure feedback control
01, the supercharging pressure feedback control by the exhaust control valve 53 is stopped, the exhaust control valve small opening control duty solenoid valve D.SOL.2 is fully closed, and the exhaust pressure is controlled via the positive pressure passage 64b. Is introduced directly into the positive pressure chamber 54a of the actuator 54 without being leaked by the duty solenoid valve D.SOL.2, 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 rotation 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 mode.

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 switching control, F3 = 0 when the first routine is executed, so that step S3 is executed.
5, first, the exhaust control valve opening delay time setting table is referred to with interpolation calculation based on the vehicle speed VSP, and the exhaust control valve 53 is fully opened (the second exhaust control valve Switching solenoid valve SOL.4 to O
An exhaust control valve opening delay time T1 which determines the timing of turning on from the FF) is set. In step S36, the intake control valve opening delay time setting value table is referenced with interpolation calculation based on the vehicle speed VSP, and the exhaust control valve 53 After the full opening control, the opening control of the intake control valve 55 (the intake control valve switching solenoid valve S
OL. 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.
Further, in step S37, the differential pressure between the upstream pressure PU and the downstream pressure PD of the intake control valve 55 (read value of the differential pressure sensor 80) DP
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. 10 is a conceptual diagram of the exhaust control valve opening delay time setting table, and FIG. 11 is a conceptual diagram of the 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 T increases.
1 and the intake control valve opening delay time T2 is shortened to fully open the exhaust control valve 53 and the intake control valve 55
, That is, the timing for switching to the twin turbo mode is advanced, the acceleration response is made uniform regardless of the vehicle speed, and the drivability is improved.

The area in which the single-to-twin switching control is actually required is limited to a stop (VSP = 0 km / h), an upshift, and the like. The transition from single to twin switching control due to air blowing is limited, and the drivability is improved by optimizing the timing of switching to the twin turbo mode for each vehicle speed during an upshift. Therefore, each delay time setting table can be simplified to a 4 to 5 grid table by using a free grid table (unequally spaced grid table) for precisely setting the delay times T1 and T2 of the required area. It is.

FIG. 12 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. 15) 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 The opening timing is advanced, and the acceleration response is improved.

The delay times T1, T2,
After setting the intake control valve opening differential pressure DPSST, the routine proceeds to step S38, in which the differential pressure search flag F3 is set, and the routine proceeds to step S39.

In step S39, the second 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 routine jumps to step S49, where the second exhaust control valve switching solenoid valve SOL. 4 is kept ON, and SOL. When 4 = OFF, since the exhaust control valve fully open control has not been executed, the process proceeds to step S40, where the control valve switching time count value C1 and the exhaust control valve opening delay time T1 are compared, and after the transition from the single to the twin switching control. It is determined whether the exhaust control valve opening delay time T1 has elapsed.

If C1 ≧ T1, the process jumps to step S47 to jump to the second exhaust control valve switching solenoid valve SOL. 4 is turned ON, and the exhaust control valve 53 is fully opened. Before the delay time of C1 <T1 elapses,
Proceeding to step S41, 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 set in step S4, and TP <TP2-W
In the case of GS, the process returns to step S14 to stop the single-to-twin switching control and immediately switch to the single turbo mode. This is to eliminate the uncomfortable feeling of driving by returning to the single turbo mode when the engine load TP decreases.

More specifically, as shown in FIG. 7, when the engine operating state once crosses the single-to-twin switching determination line L2 (TP2) from the single turbo region toward the twin-turbo region, the twin-to-single switching determination line is established. L1
(Twin → single switching judgment value TP1, details will be described later)
, The exhaust control valve 53 is fully opened after the delay time T1 has elapsed (Step S
47) Further, if the differential pressure DPS reaches the intake control valve opening differential pressure DPSST after the delay time T2 has elapsed, the intake control valve 55
Opens (step S52), and the mode is switched to the twin turbo mode. Therefore, once the signal exceeds the single-to-twin switch determination line L2, the twin-to-single switch determination line L1
If the operating state remains in the area surrounded by the single and twin switching determination line L2, the twin turbo mode is switched after the delay time has elapsed. However, in this region, as shown in FIG. 23, 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, and the single turbo mode is switched to the twin turbo mode. In other words,
A sudden decrease in the torque causes a torque shock and gives the driver an uncomfortable feeling.

In order to cope with this, the twin-to-single switching determination line L1 is changed to the single-to-twin switching determination line L1.
2 and the width (hysteresis) of both switching lines should be reduced, but if the width between both switching determination lines L1 and L2 is reduced, the frequency of switching between single turbo and twin turbo increases, and Since the negative pressure capacity of the surge tank 60 as a negative pressure source to be operated is insufficient, the surge tank 60
If the operating state stays in the vicinity of the single-to-twin switch determination line L2 if the width is too narrow, the change in the engine delay TP, which is a parameter for turbo switching, will cause the switching delay time to decrease. There is a disadvantage that the boost pressure relief valve 57 without setting causes chattering.

In order to prevent these, the operating condition is changed from single to
After crossing 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 from the single to twin switching determination line L2. Single-twin switching determination stop line L3 (= TP2-WG)
If S) exceeds the single turbo range, the single-to-twin switching control for switching to the twin turbo mode is stopped, the system is immediately shifted to the single turbo mode, and the single turbo mode in which only the primary turbocharger 40 operates is maintained. As a result, the operation in the low torque region in the twin turbo mode is eliminated, and the drivability is improved.

On the other hand, in step S41, TP ≧ TP2-W
In the case of GS, the process proceeds to step S42, and based on the engine speed N, the switching determination value table is referenced with interpolation calculation to set a primary turbo overspeed determination basic value EM2TP. This primary turbo overspeed determination basic value EM2TP
Is the delay time T after shifting from single to twin switching control.
This is a reference value for judging whether or not the engine operating state has shifted to the primary turbo overspeed region under the single turbo mode due to a sudden increase in the engine speed N and the engine load TP before one elapse, and is shown in FIGS. Thus, from the relationship between the engine speed N and the engine load TP at the standard atmospheric pressure, the primary turbocharger 40 reaches the critical speed in the single turbo mode, in the primary turbo overspeed region (shown by hatching in FIG. 14). The primary turbo overspeed determination line L4, which is the boundary of
Corresponding to the primary turbo overspeed determination line L4 at the standard atmospheric pressure, a series of addresses in the ROM 102 are stored in advance as a switching determination value table using the engine speed N as a parameter. The primary turbo overspeed determination line L4 is naturally set to a higher load side than the single-to-twin switching determination line L2.

In this case, the switching determination value table may be a free grid table (unequally spaced grid table) using the engine speed N as a parameter. By using the switching determination value table as a free grid table, it is possible to more precisely set the primary turbo overspeed determination basic value EM2TP in the frequently used engine speed range even with the same storage capacity, The switching timing is optimized, and turbo overspeed can be prevented, so that controllability is improved.

Next, at step S43, the atmospheric pressure ALT
Then, the judgment value atmospheric pressure correction coefficient KEM2 is set by referring to the judgment value atmospheric pressure correction coefficient table with interpolation calculation based on. FIG. 13 shows a conceptual diagram of the determination value atmospheric pressure correction coefficient table.
As shown in the figure, the judgment value atmospheric pressure correction coefficient KEM2 is 1.0 when the atmospheric pressure is equal to or higher than 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 basic value EM2TP is corrected by the determination value atmospheric pressure correction coefficient KEM2 to set the primary turbo overspeed determination value EMV2TP. As a result, as the atmospheric pressure ALT becomes lower, the primary turbo overspeed determination value EMV2TP
The primary turbo overspeed determination line L4 is shown in FIG.
In the case of the standard atmospheric pressure shown by the solid line in Fig. 5, single →
Similarly to the twin switching determination line L2, the load is corrected to a low load and a low rotation side as indicated by a dashed line, and is always set to a higher load side than the single-to-twin switching determination line L2 regardless of a change in the atmospheric pressure.

Next, in step S45, the engine load TP is compared with the primary turbo overspeed determination value EMV2TP. If TP <EMV2TP, the process proceeds to step S46, where the control valve switching time count value C1 is counted up. Exit the routine. On the other hand, TP ≧ EMV2TP, and the engine speed N,
Due to the sudden increase of the engine load TP, the engine operation region has shifted to the primary turbo overspeed region (for example, sudden acceleration,
If this is the case, the process proceeds to step S47, where the second solenoid valve SOL. 4 immediately turned on, and the exhaust control valve 53
Is fully opened, and exhaust gas is also immediately supplied to the secondary turbocharger 50 side.

Therefore, the exhaust flow of the high exhaust pressure, which has risen due to the sudden increase of the engine load TP and the engine speed N, is immediately transmitted to the primary turbocharger 40 and the secondary turbocharger 5.
0 and are distributed approximately equally. As a result, the primary turbocharger 40 is in an overspeed state due to a rapid increase in the exhaust pressure and the exhaust flow rate, thereby preventing the occurrence of surging due to reaching the critical rotational speed, and reducing the heat load, thereby reliably preventing damage. Is done.

At this time, as described above, the atmospheric pressure ALT
Is lower, the engine operating region in which the primary turbocharger 40 is in an overspeed state is expanded to a low load and a low speed side. In response to this, the engine operation region for determining the overspeed of the primary turbocharger 40 is determined. Primary turbo overspeed judgment line L
4 is corrected to a low load and a low rotation side with a decrease in the atmospheric pressure ALT, so that even if the atmospheric pressure ALT changes, it is possible to accurately judge the primary turbo overspeed, and to appropriately and irrespective of the atmospheric pressure change. It is possible to reliably prevent the primary turbocharger 40 from over-rotating 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. Since the transition of the primary turbocharger 40 to the overspeed state is determined by comparing TP with the primary turbocharger 40, the primary turbocharger 40 can be accurately determined over the entire range of the engine speed, the engine load, and the atmospheric pressure. Machine 40 can be prevented from being damaged.

After the shift from the single-to-twin switching control, when the exhaust control valve opening delay time T1 has elapsed and the process proceeds from step S40 or from step S45 to step S47, the second exhaust control valve switching solenoid valve SOL. 4 is turned on, the exhaust control valve 53 is fully opened, the rotation speed of the secondary turbocharger 50 is further increased, and the compressor 5
The compressor pressure (supercharging pressure) of the secondary turbocharger 50 between the intake control valve 55 and the intake control valve 55 also increases, and FIG.
As shown in the figure, the differential pressure D between the upstream and downstream of the intake control valve 55
PS rises.

Thereafter, the flow proceeds to step S48, in which the control valve switching time count value C1 is cleared to measure the time after the exhaust control valve is fully opened, and the flow 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. ,
If C1 <T2, it is determined that the condition for opening the intake control valve 55 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 50 of the secondary turbocharger 50
b and the secondary turbocharger 5 between the intake control valve 55
0, the boost pressure rises and the primary turbocharger 40
, And 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 the intake control valve 55 is opened.

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

In step S50, DPS <DPSST
If it is determined that the control has proceeded to step S51, the count value C1 is further compared with a value obtained by adding the set value TDP to the intake control valve opening delay time T2, and if C1 <T2 + TDP, the process proceeds to step S46, where the count value C1 is counted up and the routine is exited. When C1 ≧ T2 + TDP, the process proceeds to step S52, and even if the differential pressure DPS has not reached the intake control valve opening differential pressure DPSST, the switching solenoid valve SOL. 2 to ON, and the intake control valve 55
Is opened to shift to the twin turbo mode.

That is, when the differential pressure DPS by the differential pressure sensor 80 does not increase due to the failure of the differential pressure sensor 80 system, the intake control valve 55 is not opened any time after the exhaust control valve 53 is fully opened, and the secondary The supercharging pressure between the compressor 50b of the turbocharger 50 and the intake control valve 55 is abnormally increased, and the secondary turbocharger 50 is damaged due to surging. Therefore, 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, the intake control valve 55 is opened after the set time given by T2 + TDP has elapsed. Secondary turbocharger 5 due to failure of differential pressure sensor 80 system
This prevents zero damage.

FIG. 18 is a time chart showing the state of switching from the single turbo mode to the twin turbo mode by the above single-to-twin switching control.

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 slightly, and the preliminary rotation speed of the secondary turbocharger 50 is reduced. While increasing the preliminary rotation speed of the secondary turbocharger 50 by the exhaust control valve opening delay time T1.
After the lapse of 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 increases, the differential pressure DPS increases, and after the exhaust control valve is fully opened, the intake control valve is opened. The delay time T2 compensates for the operation delay time until the exhaust control valve 53 is fully opened, and after the delay time T2 elapses, the differential pressure DPS between the upstream and downstream of the intake control valve 55 is changed to the intake control valve opening differential pressure DPSST.
Is reached, the intake control valve 55 is opened. As a result, the switching from the single turbo mode in which only the primary turbocharger 40 is operated to the twin turbo mode by operating both the turbochargers 40 and 50 is smoothly performed, and the upstream pressure PU and the downstream pressure PU of the intake control valve are further reduced. When the pressure PD becomes substantially equal, the intake control valve 55 is opened to start supercharging from the secondary turbocharger 50, so that the supercharging pressure generated during switching to the twin turbo mode is temporarily reduced. The occurrence of torque shock due to the decrease is effectively and reliably prevented.

After shifting to single-twin switching control,
Even if the set time (exhaust control valve opening delay time T1) has not been reached, when it is determined that the engine operation region has shifted to the primary turbo overspeed region under the single turbo mode according to TP ≧ EMV2TP (step S45),
As shown by the broken line in FIG. 18, the second exhaust control valve switching solenoid valve SOL. 4 is turned on and the exhaust control valve 53 is turned on.
Is fully opened and the exhaust is dispersed 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 flow rate, reaches a critical rotation speed and causes a primary surge. Damage to the turbocharger 40 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 fully opening 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 mode is quickly switched to the twin turbo mode. Therefore, as shown in the output characteristic diagram of FIG. 23, the single-turbo mode can be quickly switched from the single-turbo mode to the twin-turbo mode in which the shaft torque is high in the region on the high rotation side from 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 mode will be described. If the twin-turbo mode discrimination flag F1 is set due to the end of the single-to-twin switching control, or if the twin-turbo mode was set when the previous routine was executed, the current routine is executed, and the process branches from step S1 to step S60 according to F1 = 1. .

At steps S60 and S61, TC
It is determined whether at least one of the S control and the VDC control is operating, and if it is operating, the routine exits as it is.
Alternatively, as shown by a broken line in FIG. 5, the process jumps to step S76.

Therefore, when the operating state is in the twin turbo mode, and when one of the TCS control and the VDC control is operating, a twin → step S62 and subsequent steps which will be described later.
Until the single switching determination is made and the TCS control and the VDC control end, the twin → single switching is prohibited.

As a result, even when the engine speed is temporarily reduced by the torque reduction by the TCS control or the VDC control and the brake control, the switching from the twin to the single is not performed, and the control hunting is effectively avoided. .

On the other hand, when the TCS control or the VDC control is not in operation, the process proceeds to step S62, and after step S62, the determination of switching from twin to single is performed as usual.

First, in step S62, the turbo-switching determination value table is referred to with interpolation calculation based on the engine speed N to set a twin-to-single switching determination basic value TP1B (see FIG. 7), and the flow proceeds to step S63. , Atmospheric pressure AL
Based on T, a twin → single atmospheric pressure correction coefficient table is referenced with interpolation calculation to set a twin → single atmospheric pressure correction coefficient KSGLALT. As shown in FIG. 16, the twin →
The single atmospheric pressure correction coefficient table stores a twin-to-single atmospheric pressure correction coefficient KSGLALT having a smaller value as the atmospheric pressure ALT is reduced to 1.0 above the standard atmospheric pressure.

Then, in step S64, the twin-to-single switching determination basic value TP1B is corrected with the twin-to-single atmospheric pressure correction coefficient KSGLALT to determine the switching from the twin turbo mode to the single turbo mode.
The single switching judgment value TP1 is set.

Twin to single atmospheric pressure correction coefficient KSGLALT
Is set to a smaller value as the atmospheric pressure ALT decreases, the twin-to-single switching determination line L1 based on the twin-to-single switching determination value TP1 is different from the single atmospheric pressure indicated by the solid line in FIG. → Similar to the twin switching determination line L2, the lower the atmospheric pressure ALT is, the lower the load is and the lower the rotation speed is, as indicated by the one-dot chain line in the figure. As a result, a single to twin switching determination line L2 for determining switching from single turbo mode to twin turbo mode and a twin to single switching determination line L1 for determining switching from twin turbo mode to single turbo mode. In addition, it is possible to always set a substantially constant appropriate hysteresis regardless of changes in the atmospheric pressure ALT, effectively and reliably prevent control hunting for switching the turbocharger operation number, and furthermore, from the twin turbo mode to the single turbo mode. The driving feeling associated with switching to the turbo mode can be made substantially the same regardless of changes in the atmospheric pressure ALT.

Next, the routine proceeds to step S65, where the engine load TP is compared with the twin-to-single switching determination value TP1. If TP> TP1, the current operating region is in the twin-turbo region. Flag F4
Is cleared, and in step S67, the single turbo region duration count value C2 for counting the single turbo region duration after shifting to the single turbo region is cleared. Then, the process jumps to step S76, and the process proceeds to steps S76 to S79. Switching solenoid valve for supply pressure relief valve SOL. 1. Switching solenoid valve for intake control valve SO
L. 2. First and second exhaust control valve switching solenoid valves S
OL. 3 and 4 are turned on, respectively, and the boost pressure relief valve 5
7 is closed, the intake control valve 55 and the exhaust control valve 53 are both kept fully open, the twin turbo mode discrimination flag F1 is set in step S80, the process returns to step S23, and the control valve switching time count value C1 is cleared. Then, exit the routine.

In the twin turbo mode, the supercharging pressure relief valve 57 is closed, the intake control valve 55 and the exhaust control valve 5 are closed.
By fully opening 3, the secondary turbocharger 50 in addition to the primary turbocharger 40 is fully operated, and the turbochargers 40 and 50 are in the twin turbo mode by the supercharging operation. Compressed air by the supercharging of 50 is supplied to the intake system, and as shown in the output characteristics of FIG. 23, 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 S65 that TP≤TP1, that is, if the current operation region has shifted to the single turbo region (see FIG. 15) at the boundary of the twin-single switching determination line L1, the process proceeds to step S68. Referring to the value of the determination value search flag F4, if F4 = 0, the process proceeds to step S69, and if F4 = 1, the process proceeds to step S7.
Jump to 1.

The determination value search flag F4 is cleared when the engine is in the twin turbo mode and the engine load TP is in the twin turbo range with the engine load TP being on the boundary of the twin → single switching determination line L1 (TP1) (step S6).
6). Therefore, after TP ≤ TP1, in the first routine execution, the process proceeds to step S69, where the single turbo region duration time determination value T4 is referred by referring to the single turbo region duration time determination value table with interpolation calculation based on the engine load TP.
Set. This determination value T4 is determined after the engine operating state shifts from the twin turbo range to the single turbo range.
This is a reference value for switching to the single turbo mode in which only the primary turbocharger 40 operates after a predetermined time has elapsed.

FIG. 17 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, it is set to a maximum of 2.3 sec and a minimum of 0.6 sec, and is set to a smaller value as the value of the engine load TP is larger and higher. As a result, after the engine operation state shifts from the twin turbo region to the single turbo region, the time until switching from the twin turbo mode to the single turbo mode is shortened as the engine load increases.

Next, after setting the judgment value search flag F4 in step S70, the process proceeds to step S71.

In step S71, the count value C2 of the single turbo region continuation time is counted up, and in step S72, the determination value T4 is compared with the count value C2.
If C2 ≧ T4, the process proceeds to step S75, where the count value C2 is cleared, and then returns to step S14 to switch from the twin turbo mode to the single turbo mode. 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 5
When both the turbocharger 5 and the exhaust control valve 53 are closed, the mode is switched from the twin turbo mode in which both turbochargers 40 and 50 operate to the single turbo mode 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 mode to the single turbo mode is performed when the engine operation region 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 mode is accelerated. That is, high torque is required during high engine load operation, but as shown in FIG. 23, the torque (TQ2) given by the torque curve TQ2 at the time of the twin turbo on the single turbo region side of the twin → single switching determination line L1 is a boundary. For example, the torque (point B in the figure) given by the torque curve TQ1 at the time of single turbo is higher than the point A) in the figure, and if the twin turbo mode is maintained in this region, sufficient shaft torque cannot be obtained. Output performance deteriorates, and re-acceleration performance also deteriorates. For this reason, at the time of high engine load, the single turbo region continuation time determination value T
By setting 4 to a short value, the switching from the twin turbo mode to the single turbo mode is speeded up, and the operation in the low torque region in the twin turbo mode is reduced to a single torque mode with a high torque by a necessary minimum. By switching quickly (shifting from point A to point B in FIG. 23),
The output performance is improved, and the re-acceleration performance is also improved.

When the engine is operating at a low load, the torque is in a low torque state, and the torque difference between the twin turbo mode and the single turbo mode is small. Almost no torque fluctuation. For this reason, at 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. By switching from the twin turbo mode to the single turbo mode after the continuation, 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 S72, C2 <T4
If so, the process proceeds to step S73, where 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 S75.
Returning to FIG. 19, even after the engine operating range shifts to the single turbo range and before the state continues for the set time, the mode is immediately switched to the single turbo mode as indicated by the broken line in FIG. 57 is opened, the exhaust control valve 53 and the intake control valve 55 are both closed, and the supercharging operation of the secondary turbocharger 50 is stopped. Mode.

The set value TH3 is for determining an acceleration request. That is, in the single turbo region (TP <TP1), as shown in the output characteristic of FIG. 23, the region is on the low rotation side of the twin-single switching determination line L1 and is in the region where the shaft torque of the torque curve TQ2 at the time of twin turbo is low. If the twin turbo mode is maintained and the twin turbo mode is maintained in this state, sufficient acceleration performance cannot be obtained even when the accelerator pedal is depressed. for that reason,
When it is determined that an acceleration request is required during operation in this region (TH> TH3), the mode is immediately shifted to the single turbo mode, the single turbo mode is set, and the torque curve TQ1 of the high shaft torque during the single turbo is set. Thus, the acceleration responsiveness is improved.

If TH ≦ TH3 in step S73, the process proceeds to step S74, where the vehicle speed VSP and the set value VS are set.
P2 (for example, 2 km / h), and VSP> VS
If it is determined in P2 that the vehicle is running, the process proceeds to step S76, where the twin turbo mode is maintained and the VSP
If it is determined that the vehicle is in a stopped state with ≦ VSP2, the process returns to step S14 via step S75 in the same manner as described above, and immediately shifts to the single turbo mode.

The set value VSP2 is for judging the stopped state of the vehicle. If the accelerator pedal is depressed and the engine is idling while the vehicle is stopped, for example, at idle speed, the engine speed TP rises and the engine speed increases. As the engine operating range shifts from the single turbo range to the twin turbo range, the twin turbo mode is set. After the accelerator is opened, the engine load TP and the engine speed N immediately decrease, and the engine operating range decreases. Twin →
Single switching determination line L1 (see FIG. 7 or FIG. 15)
When the transition to the single turbo area is again performed after the boundary, the set time must be elapsed after the transition to the single turbo area (C
2 ≧ T4), the engine is not switched to the single turbo mode. During this time, the engine speed N decreases and drops to near the idle speed (for example, around 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, the background noise due to the engine rotation is low because the engine speed N 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 in a stopped state (VSP ≦ VS)
P2) Even if the set time has not elapsed after the shift to the single turbo range (C2 <T4), by immediately switching to the single turbo mode, each valve can be reduced before the engine speed decreases and the background noise decreases. Is completed, and the discomfort caused by the noise of the valve operation is eliminated. The switching state from the twin turbo mode to the single turbo mode at this time is shown by a dashed line in FIG.

The embodiment of the present invention has been described above. However, the present invention is not limited to this, and an engine load other than the basic fuel injection pulse width TP may be used. Further, the present invention can be applied to engines other than the horizontally opposed engine.

In this embodiment, an example has been described in which both the TCS control and the VDC control are provided as the vehicle behavior control. However, the present invention can be applied to a vehicle having at least one of the TCS control and the TDC control. Needless to say.

[0141]

As described above, according to the first aspect of the present invention, when the operating state is in the twin turbo mode in which the primary turbocharger and the secondary turbocharger are supercharged, When the vehicle behavior control is operating, the switching from the twin turbo mode to the single turbo mode is prohibited until the vehicle behavior control ends, so that the torque reduction when the vehicle behavior control is activated, In addition, even if the engine speed temporarily drops due to the brake control, unnecessary switching to the single turbo mode is prevented, and as a result, control hunting is suppressed, and good traveling performance can be obtained.

[Brief description of the drawings]

FIG. 1 is a basic configuration diagram of the present invention.

FIG. 2 is a flowchart showing a turbo switching control routine.

FIG. 3 is a flowchart showing a turbo switching control routine (continued).

FIG. 4 is a flowchart showing a turbo switching control routine (continued).

FIG. 5 is a flowchart showing a turbo switching control routine (continued).

FIG. 6 is a flowchart showing an exhaust control valve small opening control routine.

FIG. 7 is an explanatory diagram showing each switching determination value and the relationship between a single turbo region and a twin turbo region.

FIG. 8 is an explanatory diagram showing characteristics of a single to twin atmospheric pressure correction coefficient.

FIG. 9 is an explanatory diagram of an exhaust control valve small opening control mode region.

FIG. 10 is a conceptual diagram of an exhaust control valve opening delay time setting table.

FIG. 11 is a conceptual diagram of an intake control valve opening delay time setting table.

FIG. 12 is a conceptual diagram of an intake control valve opening differential pressure setting table.

FIG. 13 is a conceptual diagram of a determination value atmospheric pressure correction coefficient table.

FIG. 14 is an explanatory diagram showing a relationship between each determination line and a primary turbo overspeed region.

FIG. 15 is an explanatory diagram showing an atmospheric pressure correction state of each determination line.

FIG. 16 is a conceptual diagram of a twin to single atmospheric pressure correction coefficient table.

FIG. 17 is a conceptual diagram of a single turbo region continuation time determination value table.

FIG. 18 is a time chart showing a switching state from a single turbo mode to a twin turbo mode.

FIG. 19 is a time chart showing a switching state from the twin turbo mode to the single turbo mode.

FIG. 20 is an overall configuration diagram of an engine with a supercharger.

FIG. 21 is a circuit diagram of an electronic control unit for an engine.

FIG. 22 is a schematic explanatory diagram of a VDC control system.

FIG. 23 is an explanatory diagram showing output characteristics during single turbo and twin turbo.

[Explanation of symbols]

 40 primary turbocharger 50 secondary turbocharger VDC, TCS vehicle behavior control means

Continued on front page F-term (reference) 3D041 AA22 AA48 AA49 AB01 AC03 AC15 AC28 AD02 AD04 AD05 AD14 AD31 AD41 AE07 AE09 AE10 AE41 AF01 AF03 3G005 EA04 EA16 EA24 EA26 FA02 FA04 FA07 FA10 FA11 FA25 GA02 GB17 GB19 GB24 GB27 GC02 GB27 GD14 GD17 GD18 GD21 GE01 GE09 GE10 HA02 HA05 HA13 HA18 JA06 JA12 JA24 JA30 JA32 JA36 JA39 JA45 JA51 JB11 JB17 JB20 3G092 AA01 AA18 BA02 BA09 BB01 DB03 DC02 DC04 DG06 DG09 EA01 EA02 EA09 EA09 EA14 EA14 FA14 FA39 FB02 GA04 GA06 GA12 GA17 GA18 GB06 GB10 HA01Z HA06Z HA09Z HA16X HA16Z HC05Z HE01Z HE03Z HE08Z HF12Z HF18Z HF21Z HF23Z HF26Z 3G093 AA05 AB02 BA00 BA06 BA32 CA00 CA10 CA11 CB06 DA01 DA03 DA05 DA03 DA05 DA05 EB04 EC01 EC04 FA04 FA14 FB01 FB02 FB04 3G301 HA01 JA03 JA06 JA34 JB01 KA07 KA09 KA12 KA24 KA25 KB05 LA02 LA04 LC01 LC07 MA11 MA24 NA03 NA04 NC02 ND41 NE01 NE06 NE17 NE19 NE22 NE23 PA01Z PA11Z PA14Z PA02Z PE03Z PE05Z PE08Z PF01Z PF02Z PF05Z PF08Z PF15Z

Claims (1)

[Claims] A turbocharger having a primary turbocharger and a secondary turbocharger, wherein the operating range is a twin turbo range in a high-speed range in which both turbochargers are supercharged, and only the primary turbocharger is supercharged. Operating region determining means for determining a current operating region based on an engine operating state by dividing the operating region into a single turbo region of a low speed region to be supplied, and operating after the operating region shifts from the single turbo region to the twin turbo region. The state is switched from the single turbo mode in which only the primary turbocharger operates to the supercharging operation to the twin turbo mode in which the supercharging operation is performed in both turbochargers, and the operation is performed after the above operation region shifts from the twin turbo region to the single turbo region. Turbo switching means for switching the state from the twin turbo mode to the single turbo mode, and according to a command from the turbo switching means A secondary turbocharger control means for controlling the operation of the secondary turbocharger, and an operation state of the vehicle behavior control means for stabilizing the behavior of the vehicle when the operating state is in the twin turbo mode, and A control device for a supercharged engine, comprising: turbo switching operation inhibiting means for inhibiting switching from the twin turbo mode to the single turbo mode when the behavior control means is operating.