JP2006097558A - Control device for engine with supercharger - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control device for an engine with a supercharger, capable of converging actual air amount on target air amount while suppressing hunting accompanied by throttle valve control. <P>SOLUTION: The control device for the engine with the supercharger is provided with the supercharger having a supercharging pressure control valve for controlling supercharging pressure; a target air amount setting means setting target air amount in accordance with target torque required based on an operating state; a throttle opening setting means setting a throttle opening based on the target air amount set by the target air amount setting means; an actual air amount detecting means detecting actual air amount supplied to the engine; and a control means performing feedback control of the supercharging pressure control valve based on a difference between the actual air amount detected by the actual air amount detecting means and target air amount set by the target air amount setting means. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a control device for a supercharged engine.

  Conventionally, since the exhaust gas has a considerably high pressure (exhaust pressure), a turbocharger that increases the intake pressure or the charging efficiency by effectively utilizing the pressure of the exhaust gas is provided to improve the engine output. Vehicles equipped with a turbocharged engine are known. In such a vehicle, in order to realize an engine output that meets a driver's request, as disclosed in, for example, Japanese Patent Application Laid-Open No. 2001-227351, the engine is in-cylinder based on an engine operation state including an accelerator operation amount and an engine rotation speed. A target air amount to be sucked is set, and the throttle valve and the supercharger are controlled to achieve the target air amount.

JP 2001-227351 A

  As is well known, there is a difference between the target air amount set based on the engine operating state and the air amount actually obtained by operating the throttle valve and the supercharger to realize the target air amount. In order to cope with this, it is known to use feedback control for automatically controlling the throttle valve and the supercharger so that the actual air amount matches the target air amount. The turbocharger has a structure in which the flow rate of exhaust gas sent to the turbine is adjusted by opening and closing drive of the waste gate valve provided in the bypass passage that bypasses the turbine. Is relatively slow, and there is little fluctuation in air volume during feedback control. On the other hand, the throttle valve has a structure in which the air volume is directly adjusted by changing the cross-sectional area of the intake passage by opening and closing the valve body provided in a relatively large intake passage. Although good, the fluctuation of the air amount accompanying the drive of the throttle valve is large, and hunting in which the air amount is greatly disturbed may occur during feedback control. Hunting causes torque fluctuations and significantly reduces running stability.

  Therefore, the present invention has been made in view of the above technical problem, and provides a control device for an engine with a supercharger capable of converging an actual air amount to a target air amount while preventing hunting associated with throttle valve control. The purpose is to do.

  Accordingly, the invention according to claim 1 of the present application provides a turbocharger having a supercharging pressure control valve for controlling the supercharging pressure, and a target for setting a target air amount in accordance with a target torque required based on an operating state. Air amount setting means, throttle opening setting means for setting the throttle opening based on the target air amount set by the target air amount setting means, and actual air amount detection means for detecting the actual air amount supplied to the engine And a control means for feedback-controlling the supercharging pressure control valve based on a deviation between the actual air amount detected by the actual air amount detecting means and the target air amount set by the target air amount setting means. It is characterized by that.

  The invention according to claim 2 of the present application is the invention according to claim 1, wherein the basic control amount of the supercharging pressure control valve is set based on the throttle opening set by the throttle opening setting means. It is characterized by.

  Furthermore, the invention according to claim 3 of the present application is the invention according to claim 1 or 2, wherein the supercharger is a turbocharger, a bypass passage for bypassing the turbocharger, and the supercharger A waste gate (W / G) valve disposed in the bypass passage as a control valve, and a pressure actuator for controlling the opening and closing of the waste gate valve using a supercharging pressure as a driving source. When the supercharging pressure is equal to or lower than a predetermined value and the waste gate valve cannot be opened, feedback control of the waste gate valve is prohibited.

  According to the first aspect of the present invention, the actual air amount can be converged to the target air amount by performing feedback control of the supercharging pressure control valve of the supercharger while preventing hunting by the throttle valve control. .

  Further, according to the invention according to claim 2 of the present application, the basic control amount corresponding to the air amount expected to be obtained under the set throttle opening is set before the air amount actually changes. Therefore, the control responsiveness can be improved as compared with the case where the supercharging pressure control valve is controlled only by feedback control, thereby improving the control responsiveness and hunting by the supercharging pressure control valve. It is possible to converge to the target air amount while achieving coexistence with suppression.

  Further, according to the invention according to claim 3 of the present application, when the supercharging pressure exceeds a predetermined value and the wastegate valve is in an openable state, the wastegate valve cannot be opened. The accumulated feedback control amount is reflected to prevent the waste gate valve from fluctuating, and a stable supercharging pressure can be secured.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. As shown in FIG. 1, the turbocharged engine according to the present invention is an in-line four-cylinder engine including first to fourth cylinders # 1 to # 4. In each of the cylinders # 1 to # 4, when an intake valve (not shown) is opened, the first and second branch intake passages 2a are routed through the first and second intake ports 1a and 1b. , 2b is sucked into the combustion chamber 3 for fuel combustion. Then, fuel (gasoline) is directly injected into the air in the combustion chamber 3 from the injector 4 at a predetermined timing to form an air-fuel mixture. This air-fuel mixture is compressed by a piston (not shown), and is ignited and burned by a spark plug (not shown) at a predetermined timing. Combustion gas, that is, exhaust gas, is discharged to the first and second branch exhaust passages 6a and 6b via the first and second exhaust ports 5a and 5b when an exhaust valve (not shown) is opened. The

  An intake passage 7 (common intake passage) is provided to supply air to each of the cylinders # 1 to # 4. The intake passage 7 has dust or the like in the air in order from the upstream side in the air flow direction. An air cleaner 8 that removes air, an air flow sensor 9 that detects the flow rate of air, a blower 10a of the turbocharger 10, an intercooler 11 that cools the air that has been pressurized by the blower 10a and becomes hot, and an accelerator pedal ( There is provided a throttle valve 12 that is opened and closed in accordance with the amount of depression (not shown) to throttle air. The downstream end of the intake passage 7 is connected to a surge tank 13 that stabilizes the air flow. The surge tank 13 includes upstream ends of the first and second branch intake passages 2a and 2b of the cylinders # 1 to # 4. Is connected.

  The downstream ends of the first and second branch exhaust passages 6a and 6b of the cylinders # 1 to # 4 are connected to one exhaust passage 14 (common exhaust passage). The exhaust passage 14 is provided with a turbine 10b of the turbocharger 10 and a catalytic converter 15 using a three-way catalyst in order from the upstream side in the flow direction of the exhaust gas. A bypass passage 16 that bypasses the turbine 10b and connects the exhaust passage 14 upstream of the turbine and the exhaust passage 14 downstream of the turbine, and a wastegate valve 17 that opens and closes the bypass passage 16 are provided.

In this engine E, basically, when the exhaust gas flow rate is high, for example, at the time of high speed and high load, exhaust pressure, i.e. in order to prevent an excessive increase in the exhaust passage pressure at location P _4, wastegate valve 17 Is opened, and a part of the exhaust gas bypasses the turbine 10 b and is discharged via the bypass passage 16. The wastegate valve 17 is driven to open and close by a wastegate valve drive actuator 21. The details of the turbocharger 10 and the surrounding configuration will be described later with reference to FIG.

  Further, the engine E is provided with an EGR passage 18 that connects the exhaust passage 14 downstream of the turbine 10 b and the intake passage 7 downstream of the throttle valve 12. The EGR passage 18 is connected to the exhaust passage 14 upstream from the catalytic converter 15. The EGR passage 18 is provided with a gas cooler 19 that cools the exhaust gas (EGR gas) flowing in the EGR passage 18 and an adjustment valve 20 that controls the flow rate of air or exhaust gas flowing in the EGR passage 18. It is installed.

  Further, when the pressure Exp in the exhaust passage 14 is higher than the pressure Pb in the intake passage 7, a part of the exhaust gas in the exhaust passage 14 is converted into EGR gas according to the pressure difference and the opening degree of the regulating valve 20 as the EGR passage. It flows into the intake passage 7 via 18.

  Further, the engine main body includes a water temperature sensor 31 that detects the temperature of the cooling water that circulates in a water jacket (not shown) provided in the first to fourth cylinders # 1 to # 4, and a reference position of the crankshaft. A crank angle sensor (not shown) for detecting the rotation angle is provided. In addition to the sensors directly disposed on the engine body, for example, an accelerator opening sensor 34 that detects an accelerator opening (throttle opening) that changes according to the amount of depression of an accelerator pedal (not shown), an engine E The intake air temperature sensor 32 for detecting the temperature of intake air (intake air temperature) sucked into the intake port 3 and the engine rotation speed sensor 33 for detecting the rotation speed of the engine E are provided. ing.

  An engine control unit 30 (hereinafter referred to as ECU) for controlling the engine E is provided for the engine E having the above-described configuration. This ECU is a comprehensive control device for the engine E, which consists of a computer, and is detected by information detected from various sensors, for example, the flow rate of intake air detected by the airflow sensor 8 and the water temperature sensor 31. Engine water temperature, crankshaft rotation angle detected by the crank angle sensor, intake air temperature detected by the intake air temperature sensor 32, engine rotation speed detected by the engine rotation speed sensor 33, accelerator opening sensor 34 and idle switch (accelerator) This is a switch that is turned on when the pedal is fully closed. Here, fuel injection control is performed based on various control information such as an accelerator opening detected by a fuel flow meter and a fuel flow rate detected by a fuel flow meter. , Ignition timing control, idle speed control, air quantity control, etc. Cormorant. The ECU 30 has a control circuit (not shown) therein, and processing such as correction, calculation, and determination executed when performing various controls is performed by the control circuit.

  FIG. 2 is a diagram showing in detail the configuration of the turbocharger 10 and its surroundings. In the turbocharger 10, the energy of the exhaust gas discharged from each cylinder # 1 to # 4 is used to rotate the turbine 10b in the exhaust passage 14, and accordingly, the blower 10a in the intake passage 7 is rotated. Is driven, and the compressed air is forcibly sent to the intake system to increase the output. Here, the exhaust gas flow rate to the turbine 10b is adjusted by changing the opening degree of the wastegate valve 17 in the bypass passage 16 that bypasses the turbine 10b, and the excess flow that is brought into the intake passage 7 by the blower 10a. The supply pressure is adjusted.

  A wastegate valve drive actuator 21 that opens and closes the wastegate valve 17 is partitioned into two chambers by a diaphragm, one of which forms a pressure chamber (not shown) that communicates with the actuator control solenoid 22 via a passage 22a. The other forms a spring chamber (not shown) that houses a spring that biases the wastegate valve 17 in the closing direction. The actuator control solenoid 22 also communicates with the upstream side of the blower 10a of the intake passage 7 via the passage 22b. Further, a downstream side of the blower 10 a of the intake passage 7 and a passage 22 a between the wastegate valve drive actuator 21 and the wastegate valve control solenoid 22 are connected via a passage 23.

  In such a configuration, a part of the supercharging pressure provided by the blower 10a is used as a control pressure of the wastegate valve drive actuator 21 via the passages 23 and 22a from the downstream side of the blower 10a of the intake passage 7 to the wastegate valve drive actuator. 21 pressure chambers. The actuator control solenoid 22 is driven by the duty sent from the ECU 30, and in the opened state, a part of the control pressure of the actuator 21 is passed to the upstream side of the blower 10a of the intake passage 7 through the passages 22a and 22b. The control pressure supplied to the pressure chamber of the wastegate valve drive actuator 21 changes according to the amount of leakage. That is, the supercharging pressure of the turbocharger 10 determined based on the open / closed state of the wastegate valve 17 is controlled by the duty sent to the actuator control solenoid 22. Basically, as the duty increases, the opening degree of the actuator control solenoid 22 increases, and the amount of leakage through the passages 22a and 22b upstream of the blower 10a in the intake passage 7 increases. The control pressure supplied to the pressure chamber of the actuator 21 decreases, the opening degree of the waste gate valve 17 decreases, and the supercharging pressure increases.

  FIG. 3 shows a basic map relating to the duty for driving the actuator control solenoid 22. In this map, the duty according to the engine speed and the accelerator opening of the throttle valve 12 is set. In a low load state (for example, a state where the accelerator opening is about 25% or less), regardless of the engine speed, 0 is used as the duty, the wastegate valve 17 is opened, and the turbocharger 10 The supercharging pressure is suppressed. Further, in a high load state (a state where the accelerator opening exceeds about 25%), the engine speed is in a range up to about 2200 rpm, the duty is 50, and the engine speed is in a range of about 2200 to 3700 rpm. The duty is 22 to 44, and the engine speed is in the range of about 3700 to 6000 rpm, and the duty is 22 to 28. For example, when the engine speed does not increase and the engine is in a high load state, such as when starting acceleration, a large duty is set and the boost pressure is increased. A small duty is set to suppress the supercharging pressure.

  In the present embodiment, when the ECU 30 performs the air amount control for realizing the target air amount to be sucked into the cylinders # 1 to # 4 set according to the depression amount of the accelerator pedal and the operating state, the throttle valve 12 In order to prevent hunting, the throttle valve 12 is subjected to open loop control, and the target air amount is continuously calculated while the throttle valve 12 is kept open. The difference in the air amount is calculated, and feedback control is performed based on the air amount. Hereinafter, the control of the throttle valve 12 and the turbocharger 10 executed by the ECU 30 will be described in detail.

  FIG. 4 is an explanatory diagram showing the flow of open-loop control of the throttle valve 12. Blocks B1 to B9 in FIG. 4 represent individual processing steps executed by the ECU 30.

  First, the block B1 is a block for determining the virtual accelerator opening. In this block B1, the accelerator opening detected by the accelerator opening sensor 34 and the gear stage (gear ratio of the transmission) of the transmission (not shown) are input and preset by the ECU 30 for each gear stage. Based on the correlation characteristic between the actual accelerator opening and the virtual accelerator opening, the virtual accelerator opening is determined and output.

  Next, in the block B2, the virtual accelerator opening output from the block B1 and the engine speed detected by the engine speed sensor 33 are input, and the target air amount (previously set by the ECU 30 for each gear stage) ( A map for determining target ce) is referred to, and a predetermined target ce is output. For example, the lower the gear stage, the higher the driving force. Therefore, the throttle valve 12 is set to a smaller opening and the target ce becomes smaller. On the other hand, the higher the gear stage, the lower the driving force. The opening degree of 12 is set large, and the target ce becomes large.

  In block B3, the target ce output from block B2 and the guard value related to the target ce calculated in advance for each gear stage are input, and the target ce is regulated for each gear stage. For example, in response to the tendency that each gear does not have a high output at a low speed stage, if the target ce set in block 2 is equal to or greater than a predetermined value, the output is limited. The

  In block B4, the intake air density is input, and a density correction coefficient corresponding to this is output. This density correction coefficient is multiplied by the regulated target ce output from the block B3 in order to correct the intake air density. For example, when the atmospheric pressure drops and the oxygen density decreases at high altitudes, or when the viscosity of the engine oil increases and the internal friction of the engine increases when it is cold, air is usually used to ensure a predetermined or higher oxygen density. Although the amount is increased, the density correction coefficient is multiplied by the target ce after regulation, so that the engine output is prevented from becoming excessive with the increase in the air amount, and the engine reliability is ensured. The

  In block B5, the gear, engine speed, and acceleration speed are input, and a torque correction coefficient corresponding to these is output. This torque correction coefficient is multiplied by the target ce after being multiplied by the density correction coefficient output from the block B4. For example, since the driving force is higher at lower speeds, the torque is likely to be excessive during acceleration, but the torque during acceleration is suppressed by multiplying the target ce by the torque correction coefficient.

  In the block B6, the target ce after being multiplied by the torque correction coefficient output from the block B5 and the air amount that becomes the injection limit of the fuel supply system that supplies the injector 4 with pressurized fuel are input. The target ce regulated with respect to the injection limit of the system is output. For example, when fuel cannot be injected within a predetermined injection period, such as when the fuel pressure decreases due to an abnormality in the fuel supply system, the required amount of injection in the injector 4 may exceed the discharge capacity of the fuel supply system, resulting in a shortage of fuel. However, this situation is avoided by multiplying the target ce by the amount of air that becomes the injection limit of the fuel supply system. Note that at the normal time, the target ce related to the injection limit of the fuel supply system is not regulated.

  In block B7, the final target ce (mass flow rate) output from block B6 is input, converted into volumetric efficiency using a conventionally known calibration formula, and then the target volumetric efficiency (target ve) ) Is output. In block B8, the target ve output in block B7 and the engine speed are input, and a map for determining the target accelerator opening (target tvo) preset in the ECU 30 for each gear stage is referred to. A target tvo (%) corresponding to ve and the engine speed is output. In block B9, driving power for a throttle actuator (not shown) for driving the throttle valve 12 is calculated in order to realize the target tvo output from the block B8. The calculated drive power is output to the throttle actuator.

  Thus, according to the processing of blocks B1 to B9, the target ce is set according to the target torque required for the operating state such as the accelerator opening and the engine speed, and the accelerator opening is determined based on the target ce. The throttle valve 12 is controlled according to the calculated accelerator opening.

  FIG. 5 is an explanatory diagram showing a flow of feedback control of the turbocharger 10. Blocks B11 to B15 in FIG. 5 represent individual processing steps executed by the ECU 30.

  First, in block B11, the accelerator opening of the throttle valve 12 and the engine speed are input, and a basic map as shown in FIG. 3 is referred to drive the actuator control solenoid 22 to obtain a predetermined boost pressure. A target duty for generating the output is output. The accelerator opening input here is the accelerator opening calculated based on the target ce in the flow of throttle valve control shown in FIG. The target duty output from the block B11 is multiplied by a pre-calculated atmospheric pressure correction factor and an intake air temperature correction factor, respectively, or a pre-calculated battery voltage correction factor is added. And corrected for battery voltage.

  In block B12, the difference between the target air amount (target ce) input from the outside and the actual air amount (actual ce) (target ce-actual ce) is multiplied by a predetermined correction coefficient, so that the air A feedback correction term by proportional control related to the quantity is calculated.

  In block B13, the difference (target ce-actual ce) between the target air amount (target ce) input from the outside and the actual air amount (actual ce) is integrated over time in the same manner as in block B12. By multiplying the value by a predetermined correction coefficient, a feedback correction term by the air amount based integral control is calculated.

  The feedback correction term calculated in the blocks B12 and B13 is added to the target duty after correction with respect to the atmospheric pressure, the intake air temperature, and the battery voltage. The duty after the feedback correction term is added is output to the actuator control solenoid 22 as the final duty.

  FIG. 6 shows a time chart of various parameters obtained under the open loop control of the throttle valve 12 shown in FIG. 4 and the feedback control of the turbocharger 10 shown in FIG. Here, the accelerator opening is ensured to a predetermined opening, and the air amount, the supercharging pressure by the turbocharger 10 and the actuator control solenoid 22 are controlled to drive in the process of gradually increasing the engine speed. A change in duty (W / G duty in the figure) is shown. As for the supercharging pressure, an upper limit value (supercharging pressure guard value) is set in order to prevent the exhaust gas flow rate from becoming excessive and causing trouble in the turbocharger 10, so as not to exceed this. Control.

  When the supercharging pressure increases as the air amount increases and exceeds a predetermined value (F / B start supercharging pressure), feedback control of the supercharging pressure based on the air amount is started and the actuator control solenoid 22 is driven and controlled. The duty for this is changed from the basic duty indicated by the solid line to the F / B control duty indicated by the broken line. Based on this F / B control duty, the turbocharger 10 is controlled, so that the actual air amount is converged to the target air amount.

  If the supercharging pressure is equal to or lower than a predetermined value (F / B start supercharging pressure), the waste gate valve 17 cannot be opened, and the feedback control of the waste gate valve 17 is prohibited. Thereby, when the supercharging pressure exceeds a predetermined value and the wastegate valve 17 is in a state in which the wastegate valve 17 can be opened, the feedback control amount accumulated in a state in which the wastegate valve 17 cannot be opened is reflected. It is possible to prevent the waste gate valve 17 from fluctuating and to secure a stable supercharging pressure.

As is clear from the above description, the ECU 30 performs open-loop control of the throttle valve 12 and feedback control of the turbocharger 10 based on the air amount when controlling the air amount for realizing the target air amount. The air amount can be converged to the target air amount while suppressing the hunting associated with the throttle valve control. Further, in controlling the turbocharger 10, a basic control amount corresponding to the air amount expected to be obtained based on the set accelerator opening is set before the air amount actually changes. Therefore, the control responsiveness can be improved as compared with the case where the wastegate valve 17 is controlled only by the feedback control, and thereby the control responsiveness to the target ce by the accelerator opening and the turbocharging. The air amount can be converged to the target air amount while achieving both ce stability by machine control.
In the above-described embodiment, the turbocharger 10 is used. However, the present invention can also be applied to a supercharger that performs supercharging mechanically.

  By the way, in particular, when the turbocharger 10 is employed, the oxygen density decreases at a location where the atmospheric pressure is low, such as a high altitude. Therefore, in order to achieve the target air amount, the turbocharger 10 is driven to produce a large amount. Although it is necessary to suck in air, in this case, the turbo overpressure machine 10 may be in an over-rotation state, such as seizure of the turbine shaft 10c (see FIG. 1) as the exhaust gas flow rate increases. In order to prevent this, the ECU 30 controls the supercharging pressure in response to the detection of the overspeed of the turbo overpressure machine 10, and uses the difference between the target air amount and the actual air amount to perform feedback control based on the air amount. Therefore, switching to the supercharging pressure-based feedback control using the difference between the target supercharging pressure and the actual supercharging pressure or a combination of both may be performed, thereby suppressing an increase in the exhaust gas flow rate. Hereinafter, the supercharging pressure-based feedback control performed according to the overspeed of the turbo booster 10 will be described.

  In the present embodiment, the detection of the overspeed of the turbine 10b is performed based on the actual boost pressure detected by a pressure sensor (not shown) provided on the downstream side of the blower 10a, and the boost pressure is a predetermined value. If it exceeds (a value lower than the supercharging pressure guard value), it is considered that the turbocharger 10 is in an overspeed state. In the following description, the “air amount” basically represents the mass air amount.

  FIG. 7 is an explanatory diagram showing a flow of feedback control of the turbocharger 10 using blocks B14 to B16 and the like for performing boost pressure-based feedback control in addition to the configuration shown in FIG.

  In block B14, an upper limit value (supercharging pressure guard value) is calculated in order to avoid the exhaust gas flow rate becoming excessive and causing trouble in the turbocharger 10 according to the engine speed. In block B15, the atmospheric pressure and the engine speed are input, and an atmospheric pressure correction factor for correcting the supercharging pressure guard value with respect to the atmospheric pressure is calculated. Then, the atmospheric pressure correction factor calculated in block B15 is multiplied by the supercharging pressure guard value calculated in block B14, thereby outputting the target supercharging pressure. In block B16, the difference between the calculated target supercharging pressure and the actual supercharging pressure (target supercharging pressure−actual supercharging pressure) is input, and a feedback correction term based on the supercharging pressure-based integral control is calculated.

  In the configuration shown in FIG. 7, a switch SW is provided in which the blocks B13 and B16 are connected together. Normally, the feedback correction term based on the air amount based proportional control calculated in block B12 is added to the target duty, and the feedback correction term based on the air amount based integral control calculated in block B13 is added to the target duty. However, when over-rotation of the turbocharger 10 is detected, the switch SW is switched, and the feedback correction term based on the supercharging pressure-based integral control calculated in the block B16 is added to the target duty. The

  For example, when the air amount based feedback control is completely switched to the boost pressure based feedback control, the feedback control amount accumulated until that time is reset, and a shock such as a drop in output may occur. In the present embodiment, in order to avoid this, the feedback correction term based on the air amount-based proportional control calculated in block B12 is continuously added to the target duty even after the switch SW is switched. Further, the switch SW is not limited to the one described above, and both the feedback correction terms calculated in the blocks B13 and B16 are added to the target duty according to the overspeed of the turbocharger 10. Thus, it may be switched to output.

  FIG. 8 is a time chart of various parameters obtained under the open loop control of the throttle valve 12 shown in FIG. 4 and the air amount-based and boost pressure-based feedback control of the turbocharger 10 shown in FIG. Show. Here, a change in the air amount and the supercharging pressure by the turbocharger 10 in the process in which the accelerator opening is secured at a predetermined opening and the engine speed gradually increases is shown.

  As the engine speed increases, the amount of air increases, the pressure due to the exhaust gas flow rate increases, and the overcharge of the turbocharger 10 is detected, as described above with reference to FIG. By performing the supercharging pressure-based feedback control, the actual supercharging pressure is converged to the target supercharging pressure, and the air amount is suppressed.

  FIG. 9 is a flowchart for the open loop control of the throttle valve 12 included in a series of control processes executed by the ECU 40. In this process, first, various parameter signals are read (# 11). Specifically, the engine water temperature detected by the water temperature sensor 31, the amount of air taken into the cylinder 2 detected by the airflow sensor 9, the engine speed detected by the engine speed sensor 33, and the accelerator opening sensor 34 The accelerator opening detected by is read. Next, the virtual accelerator opening is calculated based on the correlation characteristic between the actual accelerator opening and the virtual accelerator opening preset by ECU 30 for each gear (# 12).

  Subsequently, a predetermined map is referred to, and a target air amount (target ce) corresponding to the virtual accelerator opening and the engine speed is calculated (# 13). Further, a guard value for target ce is calculated for each gear (# 14). Then, it is determined whether or not the target ce calculated in # 13 is larger than the guard value calculated in # 14 (# 15). As a result, when it is determined that the target ce is larger than the guard value, the target ce is regulated to match the guard value, while when the target ce is determined to be equal to or less than the guard value, Looped to # 17.

  In # 17, the target ce density is corrected by multiplying the target ce by a density correction coefficient corresponding to the intake air density. This suppresses the engine output from becoming excessive with an increase in the amount of air in a place with a low air density, such as a high altitude. Thereafter, the torque is corrected for each gear stage by multiplying the target ce by a torque correction coefficient corresponding to the gear stage, engine speed and acceleration speed (# 18). Thereby, the final target ce is calculated (# 19).

  Next, an injection limit ce, which is an injection limit of a fuel supply system that supplies pressurized fuel to the injector 4, is calculated (# 20), and subsequently whether or not the final target ce is larger than the injection limit ce. Is determined (# 21). As a result, when it is determined that the final target ce is larger than the injection limit ce, the final target ce is regulated to match the injection limit ce, while the final target ce is the injection limit If it is determined that it is equal to or less than ce, the process loops to # 23.

  In # 23, the final target ce (mass flow rate) is converted into the target volume efficiency. Subsequently, a predetermined map is referred to, and a target accelerator opening (target tvo) corresponding to the target volume efficiency and the engine speed is calculated (# 24). Thereafter, drive power corresponding to the target accelerator opening is output to the throttle actuator (# 25). Thus, the process is returned to the main routine.

  FIG. 10 is a flowchart for feedback control of the turbocharger 10 included in a series of control processes executed by the ECU 40. This flowchart corresponds to the configuration of FIG. 7 in which feedback control based on air amount and boost pressure is used in combination.

  In this process, first, various parameter signals are read (# 31). Specifically, the engine water temperature detected by the water temperature sensor 31, the amount of air taken into the cylinder 2 detected by the airflow sensor 9, the engine speed detected by the engine speed sensor 33, and the accelerator opening sensor 34 The accelerator opening detected by is read.

  Next, a map as shown in FIG. 3 is referred to, and a target duty corresponding to the accelerator opening and the engine speed is calculated (# 32). Thereafter, the target duty is corrected with respect to the atmospheric pressure by multiplying the atmospheric pressure correction factor calculated in advance (# 33). Further, the target duty is corrected with respect to the intake air temperature by multiplying the intake air temperature correction factor calculated in advance (# 34). Furthermore, the target duty is corrected with respect to the battery voltage by adding a battery voltage correction coefficient calculated in advance (# 35).

  Subsequently, it is determined whether or not the supercharging pressure by the turbocharger 10 is larger than a predetermined value (# 36). As described with reference to FIG. 2, the drive source of the wastegate valve drive actuator 21 that drives the wastegate valve 17 to open and close is the supercharging pressure provided in the intake passage 7. The supercharging pressure needs to exceed the urging force of the spring accommodated in the spring chamber, that is, larger than a predetermined value. As a result of # 36, when it is determined that the supercharging pressure is larger than the predetermined value, the feedback correction term by the proportional control regarding the air amount is continuously calculated (# 37). On the other hand, when it is determined that the supercharging pressure is equal to or less than the predetermined value, the feedback correction term based on the air amount based proportional control and integral control is set to 0 (# 43), and then looped to # 44. The

  After # 37, a determination value for determining that the turbocharger 10 is in an overspeed state is calculated (# 38). Here, as the value for determining that the turbocharger 10 is in the over-rotation state, a lower value is set as the atmospheric pressure decreases. As a result, for example, feedback control based on the supercharging pressure can be used at the earliest possible in high altitudes, and the overspeed of the turbocharger 10 is suppressed. In the present embodiment, the rotational state of the turbocharger 10 is determined by detecting the supercharging pressure using a supercharging pressure sensor (not shown). For this reason, a predetermined supercharging is used as the determination value. Pressure is set.

  Subsequently, whether or not the turbocharger 10 is in an overspeed state is determined based on the determination value calculated in # 38 (# 39). As a result, when it is determined that the turbocharger 10 is not in an overspeed state, a feedback correction term based on integral control related to the air amount is calculated (# 42), and the process loops to # 44. On the other hand, when it is determined that the turbocharger 10 is in the overspeed state, the maximum guard value related to the supercharging pressure is continuously calculated (# 41). This guard value is a value higher than the determination value for determining the excessive rotation of the turbocharger 10 calculated in # 38. After that, a feedback correction term based on integral control related to the supercharging pressure is calculated (# 41), and the process loops to # 44.

  In # 44, the feedback correction term calculated in # 37 and the feedback correction term calculated in # 41, # 42 or # 43 are added to the target duty obtained in # 32 to # 35. Thus, the final duty is calculated. Then, the final duty is output to the actuator control solenoid 22 (# 45). Thus, the process is returned to the main routine.

  As is clear from the above explanation, in a place where the atmospheric pressure is low, such as at high altitude where the volume air volume for achieving the target mass air volume increases, the actual air volume is less than the target mass air volume. When the rotational speed of the turbocharger 10 becomes equal to or higher than a predetermined determination value as the volume air volume increases, the rotational speed of the turbocharger 10 increases when the target mass air volume control is continued. And the reliability of the turbocharger 10 can be ensured. Further, when switching from the air amount based feedback control to the boost pressure based feedback control, the feedback correction term by the air amount based proportional control calculated in the block B12 is continuously added to the target duty, so that the integration is performed. It is possible to avoid a shock such as a drop in the output due to the reset feedback control amount being reset.

  Note that the present invention is not limited to the illustrated embodiment, and it is needless to say that various improvements and design changes can be made without departing from the gist of the present invention.

  The supercharger-equipped engine control apparatus according to the present invention is applicable to any apparatus as long as it includes a vehicle such as an automobile and is equipped with a supercharged engine.

1 is a diagram schematically showing a turbocharged engine according to an embodiment of the present invention and a system configuration for controlling the engine. FIG. It is a figure which shows the structure of a turbocharger and its periphery. It is a basic map regarding the duty for actuator control solenoid drive. It is explanatory drawing showing the flow which performs an open loop control of a throttle valve. It is explanatory drawing showing the flow which feedback-controls a turbocharger on the air quantity basis. 6 is a time chart of various parameters obtained under the open loop control of the throttle valve shown in FIG. 4 and the feedback control of the turbocharger shown in FIG. 5. It is explanatory drawing showing the flow which feedback-controls a turbocharger on the air quantity base and a supercharging pressure base. FIG. 8 is a time chart of various parameters obtained under the open loop control of the throttle valve shown in FIG. 4 and the feedback control based on the air amount base and the boost pressure base of the turbocharger shown in FIG. 7. It is a flowchart about throttle valve control. It is a flowchart about turbocharger control.

Explanation of symbols

E ... engine with turbocharger, 1a ... first intake port, 1b ... second intake port, 2a ... first branch intake passage, 2b ... second branch intake passage, 3 ... combustion chamber, 4 ... injector, 5a ... 1st exhaust port, 5b ... 2nd exhaust port, 6a ... 1st branch exhaust passage, 6b ... 2nd branch exhaust passage, 7 ... Intake passage, 8 ... Air cleaner, 9 ... Air flow sensor, 10 ... Turbocharger, 10a ... Blower, 10b ... Turbine, 11 ... Intercooler, 12 ... Throttle valve, 13 ... Surge tank, 14 ... Exhaust passage, 15 ... Catalytic converter, 16 ... Bypass passage, 17 ... West gate valve, 18 ... EGR passage, 19 ... Gas cooler , 20 ... regulating valve, 21 ... waste gate valve drive actuator, 22 ... actuator control solenoid, 30 ... ECU, 31 ... water temperature sensor, 32 ... intake air temperature sensor Sa, 33: engine speed sensor, 34 ... accelerator opening sensor.

Claims (3)

A supercharger equipped with a supercharging pressure control valve for controlling the supercharging pressure;
Target air amount setting means for setting a target air amount in accordance with a target torque required based on the operating state;
Throttle opening setting means for setting the throttle opening based on the target air amount set by the target air amount setting means;
An actual air amount detecting means for detecting an actual air amount supplied to the engine;
Control means for feedback-controlling the supercharging pressure control valve based on a deviation between the actual air amount detected by the actual air amount detecting means and the target air amount set by the target air amount setting means. A supercharger-equipped engine control device.   2. The supercharger-equipped engine control device according to claim 1, wherein the basic control amount of the supercharging pressure control valve is set based on the throttle opening set by the throttle opening setting means. The turbocharger is a turbocharger, a bypass passage for bypassing the turbocharger, a wastegate (W / G) valve disposed in the bypass passage as the supercharger control valve, A pressure actuator that opens and closes the wastegate valve using a supply pressure as a drive source,
3. The control means for prohibiting feedback control of the waste gate valve when the supercharging pressure is not more than a predetermined value and the waste gate valve cannot be opened. The control apparatus of the engine with a supercharger as described in 2.

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