JP2004204741A - Controlling device for engine with turbo supercharger - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the occurrence of a torque shock and facilitate smooth control of a target supercharge pressure throughout a wide operation region. <P>SOLUTION: An ECU fully closes an exhaust cut valve and a waste gate valve in case the number of revolutions of an engine is in a low rotation operation region. Further, a supercharge pressure is controlled by the waste gate valve with the exhaust cut valve fully opened in a case of an operation region where a throttle opening is high and the number of revolutions of an engine is in an operation region being a little high rotation. In this case, an engine operation state to suppress a fuel consumption amount is selected, and both the exhaust cut valve and the waste gate valve are fully opened in case the number of revolutions of an engine is in a low rotation state and a throttle opening is low. And, in case there is a fear that fuel is inferior gasoline, the waste gate valve is fully opened and supercharging is not carried out. Further, a target supercharging pressure according to fluctuation of an octane value of fuel is set. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention particularly relates to a turbocharger in which a turbine scroll portion is constituted by a plurality of exhaust passages, an exhaust cut valve is provided at at least one of the exhaust passages, and a wastegate valve is provided in a passage bypassing the turbine. The present invention relates to a control device for an engine.
[0002]
[Prior art]
Conventionally, the supercharging characteristics of a turbocharger are determined by the characteristics of a compressor and the characteristics of a turbine. Therefore, a turbo scroll having a turbine scroll portion including a plurality of exhaust passages, an exhaust cut valve provided at at least one passage entrance portion of the exhaust passage, and a waste gate valve having a waste gate valve in a bypass passage that bypasses the turbine. Engines with a supercharger are known.
[0003]
As such a technology in which the turbine scroll portion is constituted by a plurality of exhaust passages, the wastegate valve and the exhaust cut valve are fully closed in a low engine speed region to improve the responsiveness of the target supercharging pressure. When the boost pressure reaches a predetermined value, the wastegate valve is opened to maintain the boost pressure. Then, an exhaust cut valve is opened when an intake air amount reaches a predetermined amount to prevent a decrease in engine output due to an increase in exhaust pressure (for example, see Patent Document 1).
[0004]
Further, when the exhaust pressure is equal to or lower than the predetermined exhaust pressure, the exhaust cut valve is closed, and the exhaust gas is supplied to the turbine only from the main passage, thereby increasing the flow rate of the exhaust gas and quickly increasing the supercharging pressure. When the exhaust pressure reaches a predetermined value, the exhaust cut valve is opened to supply exhaust gas to the turbine from the main passage and the sub passage, thereby preventing a decrease in engine output due to an increase in exhaust pressure and controlling the supercharging pressure by a wastegate. There is also disclosed a valve that is controlled by a valve so that the target boost pressure is calculated based on the intake air amount and the engine speed (for example, see Patent Document 2).
[0005]
[Patent Document 1]
Tokuho 5-62220 publicity
[0006]
[Patent Document 2]
Tokuho 5-74696 PR
[0007]
[Problems to be solved by the invention]
However, in the prior arts of Patent Documents 1 and 2 described above, the supercharging pressure is controlled by the wastegate valve, the exhaust cut valve lowers the exhaust pressure, and the exhaust cut valve is ON-OFF. Since the exhaust cut valve is opened and closed, there is a problem that when the exhaust cut valve shifts from the open state to the closed state, a torque shock occurs due to a change in exhaust pressure. Further, since the boost pressure must be controlled by the wastegate valve in accordance with the switching operation of the exhaust cut valve, there is a problem that it is difficult to control the target boost pressure smoothly.
[0008]
SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and is a control device for an engine with a turbocharger, which can prevent the occurrence of a torque shock and can easily control a smooth target supercharging pressure over a wide operating range. The purpose is to provide.
[0009]
[Means for Solving the Problems]
According to a first aspect of the present invention, there is provided a control apparatus for a turbocharged engine according to the present invention, wherein a turbine scroll portion of the turbocharger includes a plurality of exhaust passages, and at least one of the exhaust passages is provided. Control device for an engine with a turbocharger, comprising: an exhaust cut valve that opens and closes according to the engine operating state; and a wastegate valve that is provided in a bypass passage that bypasses the turbine and opens and closes according to the engine operating state. In the above, when the engine operation state is in an operation region of high load and high rotation, the exhaust cut valve is fully opened and the supercharging pressure is controlled by opening and closing the waste gate valve, while the engine operation state is high load and high rotation. In the case of an operation region other than the operation region from high rotation, at least the waste gate valve is fully closed, and the exhaust cut valve is opened and closed. It is characterized in that Gosuru supercharging pressure.
[0010]
A control device for a turbocharged engine according to a second aspect of the present invention is the control device for a turbocharged engine according to the first aspect, wherein the engine operating state is in a low-speed operation region. The exhaust cut valve and the wastegate valve are both fully closed.
[0011]
Further, according to a third aspect of the present invention, there is provided the control device for an engine with a turbocharger according to the first or second aspect, wherein the octane number estimation for estimating the octane number of the used fuel is performed. The wastegate valve is fully opened when the octane number of the used fuel estimated by the octane number estimation means is smaller than a preset threshold value.
[0012]
According to a fourth aspect of the present invention, there is provided a control apparatus for an engine with a turbocharger according to any one of the first to third aspects. An engine operation selecting means for selecting an engine operation state in which the fuel consumption is suppressed more than the operation state; and when the engine operation state in which the fuel consumption is suppressed is selected by the engine operation selection means, At least the exhaust cut valve is fully opened when the engine operation state is in a low load and low rotation operation region.
[0013]
Further, the control device for an engine with a turbocharger according to the present invention according to claim 5 is the control device for an engine with a turbocharger according to claim 4, wherein the engine operation selecting means suppresses the fuel consumption. When the engine operation state is selected, the wastegate valve is fully opened in addition to the exhaust cut valve when the engine operation state is in a low-load and low-speed operation region.
[0014]
In other words, the control device for the turbocharged engine according to the first aspect of the present invention is configured such that, when the engine operating state is in an operation range of high load and high rotation, at least one of the exhaust passages of the turbine scroll portion of the turbocharger. The exhaust pressure cut valve provided in the passage is fully opened, and the boost pressure is controlled by opening and closing a wastegate valve provided in a bypass passage that bypasses the turbine. On the other hand, when the engine operating state is an operating area other than the operating area where the load is higher and the engine speed is higher, at least the wastegate valve is fully closed, and the supercharging pressure is controlled by opening and closing the exhaust cut valve. As described above, the exhaust cut valve does not simply open and close in an ON-OFF manner, but performs supercharging pressure control continuously with the wastegate valve in a necessary operation region according to the engine operating state. Therefore, it is possible to prevent the occurrence of torque shock that has conventionally occurred due to the opening and closing of the exhaust cut valve, and to easily perform smooth control of the target supercharging pressure over a wide operating range.
[0015]
At this time, when the engine operating state is in the low-speed operation region, it is desirable that both the exhaust cut valve and the wastegate valve be fully closed. This is because, in the low engine speed region, the supercharging pressure does not increase so much because the exhaust gas flow rate is small, and there is no need to control the supercharging pressure, and the responsiveness to the target supercharging pressure is improved. .
[0016]
Further, the fuel cell system further includes octane number estimating means for estimating the octane number of the used fuel. When the octane number of the used fuel estimated by the octane number estimating means is smaller than a preset threshold value, the wastegate valve is fully opened. It is desirable that Here, the preset threshold value is, for example, a value for determining a bad fuel having an extremely low octane number. In the case of such a bad fuel, if supercharging is performed, knock may occur. Fully open to avoid overcharging.
[0017]
Further, the engine includes an engine operation selecting means for selecting an engine operation state in which the fuel consumption is suppressed more than a normal engine operation state, and the engine operation selection means suppresses the fuel consumption. When the operation state is selected, at least the exhaust cut valve is fully opened when the engine operation state is in the low load and low rotation operation region. That is, when the driver emphasizes fuel efficiency, the exhaust cut valve is opened, the exhaust pressure is reduced, and the pumping loss is reduced, thereby improving the fuel efficiency. At this time, it is desirable that the wastegate valve is also fully opened.
[0018]
Embodiment
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
1 to 7 show an embodiment of the present invention. FIG. 1 is an explanatory diagram of the overall configuration of a turbocharged engine, FIG. 2 is a circuit configuration diagram of an electronic control system, and FIG. FIG. 4 is a flowchart of a supercharging pressure control program for an engine, FIG. 5 is a flowchart of a normal supercharging pressure control routine using an exhaust cut valve or a wastegate valve, and FIG. FIG. 7 is an explanatory diagram of the minute table and the I minute table, and FIG. 7 is an explanatory diagram showing the relationship between the duty ratio and the valve opening.
[0019]
First, the overall configuration of a turbocharged engine to which the present invention is applied will be described with reference to FIG. In FIG. 1, reference numeral 1 denotes a turbocharged engine (hereinafter abbreviated as "engine"), and in this embodiment, a horizontally opposed four-cylinder gasoline engine. Cylinder heads 3 are provided in both left and right banks of the cylinder block 2 of the engine 1, and an intake port 4 and an exhaust port 5 are formed in each cylinder head 3.
[0020]
An intake manifold 6 communicates with the intake port 4, and a throttle body 8 communicates with an upstream gathering portion of the intake manifold 6 via an air chamber 7. An air cleaner 10 is attached to the upstream side of the throttle body 8 via an intake pipe 9, and the air cleaner 10 is communicated with an air intake chamber 11.
[0021]
An exhaust pipe 13 communicates with the exhaust port 5 via an exhaust manifold 12, and a catalytic converter 14 is interposed in the exhaust pipe 13 and communicates with a muffler 15.
[0022]
A throttle valve 16 is provided on the throttle body 8, an intercooler 17 is interposed in an intake pipe 9 immediately upstream of the throttle body 8, and a resonator chamber 18 is provided downstream of the air cleaner 10 in the intake pipe 9. Is interposed.
[0023]
The resonator chamber 18 and the intake manifold 6 are communicated with each other by a bypass passage 19 that bypasses the upstream side and the downstream side of the throttle valve 16. The bypass passage 19 has an idle speed control valve (idle A rotation speed control valve (ISC valve) 20 is interposed. Immediately downstream of the ISC valve 20, there is provided a check valve 22 that opens when the intake pressure is negative and closes when the intake pressure is supercharged by the turbocharger 21 and becomes positive. Have been.
[0024]
The turbocharger 21 has a compressor 23 disposed downstream of the resonator chamber 18 of the intake pipe 9 and a turbine 24 disposed in the exhaust pipe 13.
[0025]
The turbine scroll portion 25 on the turbine side of the turbocharger 21 is divided into two exhaust passages, a first exhaust passage 25a and a second exhaust passage 25b. An exhaust cut valve 26 capable of shutting off the flow of exhaust gas into the first exhaust passage 25a is connected to an exhaust cut valve actuator 27 at a passage entrance of the first exhaust passage 25a. It is configured to open toward the downstream side of the exhaust gas flow, and is opened and closed by an electronic control unit (ECU) 60 described later. It should be noted that the exhaust cut valve 26 is configured to open toward the downstream side of the exhaust gas flow because the exhaust cut valve 26 opens in a direction in which the exhaust cut valve 26 opens when the exhaust pressure rises above a certain level. This is because the exhaust pressure can be prevented from becoming abnormally high even if some abnormality occurs in the engine 21, which is preferable for the engine 1.
[0026]
A wastegate valve 28 is interposed at the turbine housing inlet of the turbocharger 21, and a wastegate valve operating actuator 29 is connected to the wastegate valve 28. The wastegate valve actuating actuator 29 is partitioned into two chambers by a diaphragm, one of which forms a pressure chamber communicating with the wastegate valve control duty solenoid valve 30 and the other biases the wastegate valve 28 in the closing direction. A spring chamber containing the spring is formed.
[0027]
The wastegate valve control duty solenoid valve 30 has a port communicating with the pressure chamber of the wastegate valve operating actuator 29, a port communicating with the compressor downstream of the turbocharger 21, and a port communicating with the resonator chamber 18. It has a configuration of an electromagnetic three-way valve having: Then, the valve opening of the port communicating with the resonator chamber 18 is adjusted according to the duty ratio of the control signal output from the ECU 60, and the pressure on the resonator chamber 18 side and the pressure on the downstream side of the compressor are regulated. The control pressure is supplied to the pressure chamber of the valve operating actuator 29, and the opening degree of the waste gate valve 28 is adjusted to control the supercharging pressure.
[0028]
On the other hand, an injector 31 is located immediately upstream of each intake port 4 of each cylinder of the intake manifold 6, and fuel in a fuel tank (not shown) is pressure-fed by a fuel pump (not shown), and is also fed to the injector 31 by a pressure regulator (not shown). Is regulated to a predetermined pressure.
[0029]
Further, an ignition plug 32 whose tip is exposed to the combustion chamber is attached to each cylinder of the cylinder head 3, and an igniter 34 is connected to this ignition plug 32 via an ignition coil 33 provided for each cylinder. Have been.
[0030]
Here, control regarding the turbocharger 21 will be briefly described. In the turbocharger 21, the compressor 23 is rotationally driven by exhaust energy introduced into the turbine 24, and sucks and pressurizes air to supercharge.
[0031]
At this time, the exhaust cut valve 26 of the first exhaust passage 25a of the turbine scroll portion 25 of the turbocharger 21 is controlled by a control signal such as a duty signal from the ECU 60 to an exhaust cut valve actuator constituted by a duty solenoid or a stepping motor. Opening / closing control is performed by operating 27. Similarly, the wastegate valve 28 at the inlet of the turbine housing of the turbocharger 21 is controlled by a wastegate valve control duty solenoid valve 30 in accordance with the duty ratio of a control signal output from the ECU 60, and is used for operating the wastegate valve. The control pressure is supplied to the pressure chamber of the actuator 29, and the opening of the waste gate valve 28 is adjusted.
[0032]
The opening / closing control of the exhaust cut valve 26 and the waste gate valve 28 by the ECU 60 is executed according to a flowchart shown in FIG. 4 described later, and is basically controlled according to the operating state of the engine as described below.
[0033]
That is, as shown in the explanatory diagram showing the supercharging pressure control mode set for each engine operating region in FIG. 3, the engine operating state is in the operating region where the engine speed NE is low (in the case of the supercharging pressure control mode 0). Case), both the exhaust cut valve 26 and the waste gate valve 28 are fully closed.
[0034]
When the engine operating state is such that the engine load represented by, for example, the throttle opening θth is a high load and the engine speed NE is in the operating region where the engine speed is higher than the high speed (in the case of the supercharging pressure control mode 2), the exhaust gas is exhausted. The supercharging pressure is controlled to the target supercharging pressure by fully opening the cut valve 26 and performing feedback control of the wastegate valve 28.
[0035]
Further, when the engine operating state is in an operating region other than the above-described supercharging pressure control mode 0 and the supercharging pressure control mode 2 (in the case of the supercharging pressure control mode 1), the wastegate valve 28 is fully closed, The supercharging pressure is controlled to the target supercharging pressure by feedback-controlling the exhaust cut valve 26.
[0036]
At this time, if the driver has selected an engine operation state, which suppresses fuel consumption more than a normal engine operation state, with an ECO mode switch 51 as an engine operation selection means to be described later, the engine operation state becomes the engine speed NE. Is in a low-rotation state equal to or less than a preset threshold NEC1 and in a low-load state in which the engine load (ie, throttle opening θth) is equal to or less than a preset threshold θthc1, the exhaust cut valve 26 And the waste gate valve 28 are fully opened.
[0037]
If the retard amount due to knock correction in the ignition timing control of the engine 1 is equal to or less than a preset threshold Lc1 and the octane value of the fuel is abnormally low and there is a possibility of poor gasoline, the wastegate valve 28 is fully opened. And control not to perform supercharging. As described above, in the present embodiment, the octane number of the fuel is indirectly estimated using the numerical value set by the ignition timing control in the engine 1, and the ECU 60 functions as an octane number estimation unit. have.
[0038]
Further, an ignition timing learning value in the ignition timing control of the engine 1 (a value between 0 and 1, the larger the value, the higher the octane number gasoline can be considered), is determined, and a preset threshold value (for example, 0.3 If it is equal to or less than 0.4), the fuel is determined to be low-octane gasoline, and a low target supercharging pressure set in advance for low-octane gasoline is set. Is executed. Conversely, if the fuel is larger than a preset threshold (for example, 0.3 to 0.4), the fuel is determined to be high octane gasoline, and a high target supercharging pressure preset for high octane gasoline is used. Is set, and the supercharging pressure control is executed at the target supercharging pressure. By setting the target supercharging pressure in accordance with the octane number of gasoline in this manner, knock at low octane numbers can be effectively prevented.
[0039]
As is well known, the target boost pressure in the boost pressure control is set according to the engine speed NE and the throttle opening θth from a target boost pressure table.
[0040]
Next, various sensors and switches will be described. An absolute pressure sensor 36 is provided to select and detect the intake pipe pressure downstream of the throttle valve 16 (the intake pressure in the intake manifold 6) and the atmospheric pressure by the intake pipe pressure / atmospheric pressure switching solenoid valve 37. Further, a knock sensor 38 is attached to the cylinder block 2, a cooling water temperature sensor 40 faces a cooling water passage 39 communicating between the left and right banks, and an O2 sensor 41 is mounted on the exhaust pipe 13. Further, a throttle opening sensor 42 is connected to the throttle valve 16, and an intake air amount sensor 43 is disposed immediately downstream of the air cleaner 10.
[0041]
Further, a crank rotor 45 is axially mounted on a crankshaft 44 of the engine 1, and a crank angle sensor 46 composed of an electromagnetic pickup or the like is provided on the outer periphery of the crank rotor 45. Further, a cylinder discriminating sensor 49 composed of an electromagnetic pickup or the like is provided opposite to a cam rotor 48 connected to the camshaft 47 in the valve operating mechanism.
[0042]
The crank angle sensor 46 and the cylinder discriminating sensor 49 detect protrusions formed at predetermined intervals on the crank rotor 45 and the cam rotor 48, respectively, with the operation of the engine, and output a crank pulse and a cylinder discriminating pulse. Then, the ECU 60 calculates the engine speed NE from the crank pulse interval time (projection detection interval), calculates the ignition timing, the fuel injection timing, and the like, and further calculates the cylinder based on the input pattern of the crank pulse and the cylinder discrimination pulse. Make a determination. In particular, in the ignition timing control, as is well known, an optimal ignition timing according to the operating state of the engine 1 is determined from a map according to the intake air amount and the engine speed NE stored in the ECU 60 in advance. The value is set while various learning corrections are performed using the values from the sensors. At the time of this learning correction, a retard amount, which is a correction value for the ignition advance angle, is determined in advance based on the value from the knock sensor 38.
[0043]
Further, a vehicle speed sensor 50 for detecting a vehicle speed from rotation of an output shaft of a transmission (not shown), and an ECO that enables a driver to selectively set an engine operating state that suppresses fuel consumption more than a normal engine operating state. The mode switch 51 is connected to the ECU 60.
[0044]
Next, the configuration of the electronic control system will be described with reference to FIG. The ECU 60 mainly includes a microcomputer in which a CPU 61, a ROM 62, a RAM 63, a backup RAM 64, a counter / timer group 65, and an I / O interface 66 are connected via a bus line, and supplies a predetermined stabilized power to each unit. Peripheral circuits such as a constant voltage circuit 67, a drive circuit 68, and an A / D converter 69 are provided.
[0045]
The counter / timer group 65 includes a free-run counter, various counters such as a counter for counting the input of a cylinder determination sensor signal (cylinder determination pulse), a fuel injection timer, an ignition timer, and a periodic interrupt for generating a periodic interrupt. Timers and watchdog timers for monitoring system abnormalities are collectively referred to for convenience, and also include various software counters and timers.
[0046]
The constant voltage circuit 67 is connected to the battery 71 via a first relay contact of a power relay 70 having two relay contacts. The power relay 70 has one end of a relay coil grounded and the other end of the relay coil. Are connected to the drive circuit 68. A power supply line for supplying power from the battery 71 to each actuator is connected to the second relay contact of the power supply relay 70. One end of an ignition switch 72 is connected to the battery 71, and the other end of the ignition switch 72 is connected to an input port of the I / O interface 66.
[0047]
Further, the constant voltage circuit 67 is directly connected to the battery 71, and when the ON of the ignition switch 72 connected to the battery 71 is detected at the input port of the I / O interface 66 and the contact of the power relay 70 is closed, While supplying power to each unit in the ECU 60, backup power is always supplied to the backup RAM 64 regardless of whether the ignition switch 72 is ON or OFF.
[0048]
A knock sensor 38, a crank angle sensor 46, a cylinder discrimination sensor 49, a vehicle speed sensor 50, and an ECO mode switch 51 are connected to input ports of the I / O interface 66. Further, an input port of the I / O interface 66 is connected via an A / D converter 69 to the intake air amount sensor 43, the throttle opening sensor 42, the cooling water temperature sensor 40, the O2 sensor 41, and the absolute pressure sensor 36. At the same time, the battery voltage VB is input and monitored.
[0049]
On the other hand, the output ports of the I / O interface 66 include an ISC valve 20, an injector 31, an exhaust cut valve actuator 27, a waste gate valve control duty solenoid valve 30, an intake pipe pressure / atmospheric pressure switching solenoid valve 37, and a power supply. The relay coil of the relay 70 is connected via the drive circuit 68, and the igniter 34 is connected.
[0050]
When the ignition switch 72 is turned on, the power relay 70 is turned on, a constant voltage is supplied to each unit via the constant voltage circuit 67, and the ECU 60 executes various controls. That is, in the ECU 60, the CPU 61 inputs detection signals from various sensors via the I / O interface 66 based on the control program stored in the ROM 62, and various data stored in the RAM 63 and the backup RAM 64. Calculates various control amounts based on the fixed data stored in.
[0051]
Then, as described above, the ECU 60 refers to the exhaust cut valve actuator 30 and the wastegate valve control duty through the drive circuit 68 while referring to a map or a preset threshold according to the operation state at that time. A control signal is output to the solenoid valve 33 to perform opening / closing control and supercharging pressure control. Further, a fuel injection control is performed by outputting a drive pulse width signal that determines the calculated fuel injection amount to the injector 31 of the corresponding cylinder at a predetermined timing, and outputs an ignition signal to the igniter 34 at a predetermined timing to output the ignition timing. The control is executed, and a control signal is output to the ISC valve 20 to execute idle speed control and the like.
[0052]
Hereinafter, the supercharging pressure control of the engine executed by the ECU 60 will be described with reference to the flowchart of FIG.
[0053]
First, in step (hereinafter abbreviated as "S") 101, necessary parameters are read, and the process proceeds to S102, where the ECO mode switch 51 is turned on, and the engine operating state in which the driver suppresses fuel consumption more than in the normal engine operating state It is determined whether or not is selected.
[0054]
If the result of determination in S102 is that the ECO mode switch 51 is ON, the process proceeds to S103, in which it is determined whether the engine speed NE is equal to or less than a preset threshold value NEC1 (NE ≦ NEC1) and the engine is in a low speed state. If NE ≦ NEC1 and the engine is running at a low speed, the process proceeds to S104.
[0055]
In S104, it is determined whether the engine load, that is, the throttle opening θth is equal to or less than a preset threshold value θthc1 (θth ≦ θthc1), and whether the engine is in a low load state. Then, the exhaust cut valve 26 and the waste gate valve 28 are both fully opened, and the program exits. That is, in the driving state where the fuel consumption is emphasized and the driving state is low load and low rotation, the exhaust cut valve 26 is opened to reduce the exhaust pressure, and the pumping loss is reduced to improve the fuel efficiency. At this time, the wastegate valve 28 is also fully opened to further enhance the above-described effect.
[0056]
On the other hand, in S102, the ECO mode switch 51 is turned off, or in S103, the engine speed NE is higher than a preset threshold value NEC1 (NE> NEC1), or in S104, the throttle opening degree θth is set in advance. If it is larger than the threshold value θthc1 (θth> θthc1), the process proceeds to S106.
[0057]
In S106, it is determined whether or not the retard amount by the knock correction in the ignition timing control of the engine 1 is equal to or less than a preset threshold value Lc1 (retard amount ≦ Lc1). It is determined that the gas is gasoline (ultra low octane gasoline), and the process proceeds to S107, where the waste gate valve 28 is fully opened and the program exits. That is, if supercharging is performed in the case of poor gasoline, there is a risk of knocking. Therefore, the supercharging is not performed by fully opening the wastegate valve 28. Note that the exhaust cut valve 26 is not particularly controlled because the waste gate valve 28 is fully opened.
[0058]
In S106, when it is determined that the retard amount is greater than Lc1 and it is determined that the gasoline is not bad gasoline, the process proceeds to S108, and when the engine operating state is in the operating region where the engine speed NE in FIG. Control mode 0) is determined.
[0059]
If the result of determination in S108 is that the engine operating state is in the supercharging pressure control mode 0 in the operating region where the engine speed NE is low, the process proceeds to S109, and both the exhaust cut valve 26 and the wastegate valve 28 are fully closed. Exit the program. That is, when the engine operating state is in the operating region where the engine speed NE is low, the supercharging pressure is not so high because the exhaust gas flow rate is small, and it is not necessary to control the supercharging pressure. This is to improve the response to the supply pressure (to reduce turbo lag).
[0060]
On the other hand, when it is determined that the engine operating state is not the case of the supercharging pressure control mode 0 as a result of the determination in S108, the process proceeds to S110, and the ignition timing learning value in the ignition timing control of the engine 1 (between 0 and 1). Is compared with a preset threshold value (for example, 0.3 to 0.4).
[0061]
If the ignition timing learning value is equal to or smaller than the threshold value of 0.3 to 0.4 as a result of the comparison in S110, it is determined that the gas is low octane gasoline (regular gasoline), and the process proceeds to S111, where the target supercharging for low octane gasoline is performed. Set pressure.
[0062]
On the other hand, if the ignition timing learning value is larger than the threshold value of 0.3 to 0.4 as a result of the comparison in S110, it is determined that the octane gasoline is high octane gasoline (high octane gasoline). Set the boost pressure. Here, the target boost pressure for low octane number is lower than the target boost pressure for high octane number, so that knock resistance is improved.
[0063]
After setting the target supercharging pressure in S111 or S112 in this manner, the process proceeds to S113, in which the engine operating state is changed to the supercharging pressure control mode 1 (the engine speed NE in the operating region where the engine speed NE is low) in FIG. The supercharging pressure control mode 0 region and the supercharging pressure control mode other than the supercharging pressure control mode 2 in the operation region where the engine operation state is such that the throttle opening θth is large and the engine speed NE is high. It is determined whether or not.
[0064]
If the result of determination in S113 is that the engine operating state is the supercharging pressure control mode 1, the process proceeds to S114, the wastegate valve 28 is fully closed, and the supercharging pressure control is performed by the exhaust cut valve 26 in FIG. This is executed by the feedback control shown in the flowchart.
[0065]
If the result of determination in S113 is that the engine operating state is not in the supercharging pressure control mode 1, that is, in the supercharging pressure control mode 2, the process proceeds to S115, the exhaust cut valve 26 is fully opened, and the wastegate valve 28 Then, the supercharging pressure control is executed by feedback control also shown in the flowchart of FIG.
[0066]
By performing such control, in the supercharging pressure control mode 1 in which the exhaust gas amount is relatively small, the supercharging pressure is controlled by the exhaust cut valve 26 and the first exhaust passage provided with the exhaust cut valve 26 is controlled. By applying exhaust pressure to 25a, torque shock when exhaust cut valve 26 is fully opened can be eliminated, and traveling performance can be improved.
[0067]
In addition, the exhaust cut valve 26 does not simply open and close in an ON-OFF manner, but performs supercharging pressure control continuously with the wastegate valve 28 in a necessary operation region according to the engine operating state. Therefore, it is possible to prevent the occurrence of torque shock that has conventionally occurred due to the opening and closing of the exhaust cut valve 26, and to easily perform smooth control of the target supercharging pressure over a wide operating range.
[0068]
Next, the flowchart of FIG. 5 is executed by the ECU 60 for the exhaust cut valve 26 (S114 described above) or the waste gate valve 28 (S115 described above), which is executed every predetermined cycle (predetermined time). 4 shows a normal supercharging pressure control routine (a routine of feedback control to a target supercharging pressure).
[0069]
First, in S201, the target supercharging pressure table is referred to with interpolation calculation based on the engine speed NE and the throttle opening θth as is well known, and the target supercharging pressure TPTAGT is set (TPTAGT ← TBL (NE , Θth)).
[0070]
Next, the process proceeds to S202, in which a deviation ΔP between the target supercharging pressure TPTAGT and the intake pipe pressure (actual supercharging pressure) P detected by the absolute pressure sensor 36 is obtained (ΔP ← TPTAGT-P), and in S203, the absolute value of the deviation ΔP is calculated. The value | ΔP | is compared with a set value PS that gives a dead zone, and it is checked whether the actual supercharging pressure P is within a dead zone in PI control of the supercharging pressure.
[0071]
As a result, when | ΔP | <PS and the actual supercharging pressure P is within the dead zone with respect to the target supercharging pressure TPTAGT, the process proceeds from S203 to S204, where the integral constant DI in PI control is set to 0 and (DI ← 0), the proportional constant DP is set to 0 in S205 (DP ← 0). Then, in S223, the duty ratio DUTY of the control drive signal for the exhaust cut valve actuator 27 or the waste gate valve control duty solenoid valve 30 is set to the old value obtained in the previous execution of the routine, the integration constant DI set in the current routine. And the proportional constant DP are added and set with a new value (DUTY ← DUTY + DI + DP), and the routine exits.
[0072]
On the other hand, if | ΔP | ≧ PS in S203 and the actual supercharging pressure P is out of the range of the dead zone, the process proceeds from S203 to S206, where the actual supercharging pressure P is compared with the target supercharging pressure TPTAGT to determine the target supercharging pressure TPTAGT. The magnitude relationship of the actual supercharging pressure P to the supply pressure TPTAGT is examined. When P> TPTAGT and the actual supercharging pressure P is higher than the target supercharging pressure TPTAGT outside the dead zone, the process proceeds from S206 to S207, and the duty ratio is reduced in S208 to S213. The supply pressure P is reduced.
[0073]
In the process of decreasing the duty ratio, first, in S207, the magnitude relationship between the actual supercharging pressure P and the target supercharging pressure TPTAGT is inverted, and the first time when the actual supercharging pressure P is out of the range of the dead zone is determined. Is referred to the value of the inversion initial discrimination flag FD. When P> TPTAGT and FD = 0, the inversion initial discrimination flag FD indicates that the actual supercharging pressure P has deviated from the dead zone for the first time after the actual supercharging pressure P has become higher than the target supercharging pressure TPTAGT. Sets FD = 1.
[0074]
Accordingly, when FD = 0 in S207, that is, when the actual supercharging pressure P becomes higher than the target supercharging pressure TPTAGT, and the current time deviates from the dead zone for the first time (P ≧ TPTAGT + PS), the process proceeds to S208, and the absolute value of the deviation | ΔP | The P constant table shown in FIG. 6A is referred to based on the above, and a proportional constant decrement value PDOWN that increases stepwise as the absolute value | ΔP | of the deviation increases is set.
[0075]
Then, in S209, the proportional constant decrement value PDOWN is given a minus sign to make a proportional constant DP for skip correction (DP ← -PDOWN), the integration constant DI is set to 0 in S210 (DI ← 0), and the first inversion is performed in S214. After the determination flag FD is set (FD ← 1), a new duty ratio DUTY is set in S223 described above, and the routine exits.
[0076]
If FD = 1 in S207 and the duty ratio DUTY has already been reduced by the skip correction, the process proceeds from S207 to S211 and based on the absolute value | ΔP | of the deviation, I shown in FIG. Referring to the minute table, an integral constant decrement value IDDOWN is set. As shown in FIG. 6B, the integration constant subtraction value IDDOWN increases stepwise as the absolute value of the deviation | ΔP | increases, as in the case of the above-described proportional constant decrement value PDOWN. The degree is set to be smaller than the proportional constant decrement value PDOWN.
[0077]
Next, the process proceeds from S211 to S212, in which the integral constant decrement value IDDOWN is given a minus sign to make the integral constant DI (DI ← -IDDOWN), the proportional constant DP is set to 0 in S213 (DP ← 0), and in the above-mentioned S214. After setting the inversion initial discrimination flag FD (FD ← 1), a new duty ratio DUTY is set in S223 described above, and the routine exits.
[0078]
On the other hand, if P ≦ TPTAGT in S206 and the actual supercharging pressure P is lower than the target supercharging pressure TPTAGT outside the range of the dead zone, the process proceeds from S206 to step S215, and a process of increasing the duty ratio is performed in S216 to S221. The actual supercharging pressure P is increased.
[0079]
In the process of increasing the duty ratio, the value of the first reversal determination flag FD is referred to in S215, FD = 1, and the actual supercharging pressure P shifts from a state higher than the target supercharging pressure TPTAGT to a lower state. When the vehicle deviates from the dead zone for the first time (P ≦ TPTAGT−PS), the process proceeds to S216, and the P value table is referred to based on the absolute value of the deviation | ΔP | An increasing proportional constant increment value PUP (see FIG. 6A) is set.
[0080]
Then, in S217, the proportional constant increment value PUP is set as the proportional constant DP for skip correction (DP ← PUP), the integration constant DI is set to 0 (DI ← 0) in S218, and the inversion first-time determination flag FD is cleared in S222 ( FD ← 0), a new duty ratio DUTY is set in the aforementioned S223, and the routine exits.
[0081]
If FD = 0 in S215 and the duty ratio DUTY has already been increased by skip correction, the process proceeds from S215 to S219, where the integration constant is referred to based on the absolute value | ΔP | An increment value IUP (see FIG. 6B) is set.
[0082]
Then, the process proceeds to S220, in which the integral constant increment value IUP is set as the integral constant DI (DI ← IUP), the proportional constant DP is set to 0 in S221 (DP ← 0), and the inversion initial discrimination flag FD is cleared in S222 (FD ← 0), a new duty ratio DUTY is set in S223 described above, and the routine exits. Although the integral constant increment value IUP increases stepwise as the absolute value | ΔP | of the deviation increases, similarly to the above-described proportional constant increment value PUP, the degree of the increase is smaller than the proportional constant increment value PUP. Is set.
[0083]
The relationship between the duty ratio DUTY of the control drive signal for the exhaust cut valve actuator 27 or the waste gate valve control duty solenoid valve 30 and the valve opening degree set in accordance with the flowchart of FIG. 5 is shown, for example, in FIG. The opening degree of the exhaust cut valve 26 or the waste gate valve 28 is controlled in such a manner that the duty ratio DUTY is between 20 and 80.
[0084]
【The invention's effect】
As described above, according to the present invention, the exhaust cut valve does not simply open and close in an ON-OFF manner, but continuously with the wastegate valve in a necessary operating region according to the engine operating state. Since the control is performed, it is possible to prevent the occurrence of the torque shock which has conventionally occurred due to the opening and closing of the exhaust cut valve, and to easily perform the smooth control of the target supercharging pressure over a wide operation range. .
[Brief description of the drawings]
FIG. 1 is an explanatory view of the overall configuration of an engine with a turbocharger.
FIG. 2 is a circuit configuration diagram of an electronic control system.
FIG. 3 is an explanatory diagram showing a supercharging pressure control mode set for each engine operation region;
FIG. 4 is a flowchart of an engine supercharging pressure control program.
FIG. 5 is a flowchart of a normal supercharging pressure control routine using an exhaust cut valve or a wastegate valve.
FIG. 6 is an explanatory diagram of a P-minute table and an I-minute table.
FIG. 7 is an explanatory diagram showing a relationship between a duty ratio and a valve opening degree.
[Explanation of symbols]
1 Engine with turbocharger
21 Turbocharger
23 Compressor
24 turbine
25 Turbine scroll part
25a first exhaust passage
25b Second exhaust passage
26 Exhaust cut valve
28 wastegate valve
51 ECO mode switch (engine operation selection means)
60 ECU (Octane number estimation means)

Claims (5)

An exhaust cut valve configured as a turbine scroll portion of the turbocharger with a plurality of exhaust passages, provided in at least one of the exhaust passages, and opened and closed according to an engine operating state;
A control device for a turbocharged engine provided with a bypass passage that bypasses a turbine and having a wastegate valve that opens and closes according to an engine operating state,
In the case where the engine operation state is in an operation region of high load and high rotation, the exhaust cut valve is fully opened and the boost pressure is controlled by opening and closing the waste gate valve, while the engine operation state is high load and high rotation. A control device for a turbocharged engine, wherein at least the wastegate valve is fully closed and the supercharging pressure is controlled by opening and closing the exhaust cut valve in an operating region other than the operating region. 2. The control device for a turbocharged engine according to claim 1, wherein both the exhaust cut valve and the wastegate valve are fully closed when the engine operation state is in a low rotation operation range. An octane number estimating means for estimating an octane number of the used fuel, wherein when the octane number of the used fuel estimated by the octane number estimating means is smaller than a preset threshold value, the wastegate valve is fully opened. The control device for a turbocharged engine according to claim 1 or 2. An engine operation selecting means for selecting an engine operation state in which the fuel consumption is suppressed more than a normal engine operation state, wherein the engine operation state in which the fuel consumption is suppressed is selected by the engine operation selection means. The turbocharger according to any one of claims 1 to 3, wherein at least the exhaust cut valve is fully opened when the engine operation state is a low load and low rotation operation range. Engine engine control device. When the engine operation state in which the fuel consumption is suppressed is selected by the engine operation selection means, the wastegate is added to the waste cut valve when the engine operation state is in a low-load and low-speed operation region. The control device for a turbocharged engine according to claim 4, wherein the valve is fully opened.

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