JP6234810B2 - Engine control device - Google Patents

Description

  The present invention includes a supercharger that boosts intake air of an engine, an intake air amount adjustment valve that adjusts the intake air amount of the engine, and an exhaust gas recirculation device that recirculates a part of the exhaust of the engine to the engine. The present invention relates to an engine control device that performs control according to an operating state.

  Conventionally, this type of technology has been employed in, for example, automobile engines. An exhaust gas recirculation (EGR) device guides part of the exhaust after combustion discharged from the combustion chamber of the engine to the exhaust passage to the intake passage via the EGR passage, and mixes it with the intake air flowing through the intake passage It is made to return to a combustion chamber. EGR gas flowing through the EGR passage is adjusted by an EGR valve provided in the EGR passage. By this EGR, nitrogen oxide (NOx) in the exhaust gas can be mainly reduced, and fuel efficiency can be improved at the time of partial load of the engine.

  The engine exhaust is either free of oxygen or lean. Therefore, by mixing a part of the exhaust gas with the intake air by EGR, the oxygen concentration in the intake air decreases. For this reason, in the combustion chamber, fuel burns in a state where the oxygen concentration is low, so that the peak temperature at the time of combustion is lowered and generation of NOx can be suppressed. In a gasoline engine, the pumping loss of the engine can be reduced even when the throttle valve is closed to some extent without increasing the oxygen content in the intake air by EGR.

  Here, recently, in order to further improve the fuel efficiency of the engine, it is conceivable to perform EGR in the entire operation region of the engine, and it is required to realize a large amount of EGR. In order to realize a large amount of EGR, it is necessary to enlarge the inner diameter of the EGR passage or increase the flow passage opening area of the valve body or the valve seat of the EGR valve as compared with the conventional technology.

  By the way, it is well known that an engine equipped with a supercharger is provided with an EGR device. Patent Document 1 below describes this type of technology. The supercharger includes a turbine provided in the exhaust passage and a compressor provided in the intake passage and driven by the turbine. The EGR device is a so-called low-pressure loop type EGR device, in which an EGR passage is disposed between an exhaust passage downstream of the turbine and an intake passage upstream of the compressor, and an EGR valve is provided in the EGR passage.

  In a supercharged engine equipped with this type of low-pressure loop EGR device, the path of the intake passage from the outlet of the EGR passage to the throttle valve is relatively long. Therefore, even if the throttle valve is closed toward the fully closed state when the engine is decelerated and the EGR valve is immediately fully closed in accordance with the sudden decrease in the required EGR rate, the intake passage between the outlet of the EGR passage and the throttle valve In some cases, a large amount of EGR gas may remain. For this reason, the residual EGR gas is mixed with the intake air when the engine is decelerated, and there is a possibility that the decrease in the EGR rate after the deceleration is delayed, that is, the “EGR attenuation delay” occurs. As a result, the EGR rate in the intake air taken into the combustion chamber becomes excessive, which may cause a deceleration misfire in the engine. Further, the EGR decay delay time tended to be prolonged as the engine was decelerated from the high boost pressure, or as the engine speed decreased.

  Therefore, the engine described in Patent Document 1 includes a fresh air introduction passage for introducing fresh air into the intake passage downstream of the throttle valve, and a fresh air introduction valve disposed in the fresh air introduction passage. When the required EGR rate of the engine suddenly decreases, the fresh air introduction valve is controlled to open and the throttle valve is controlled to close. As a result, when the required EGR rate suddenly decreases during engine deceleration, new air is introduced into the intake passage downstream of the throttle valve from the fresh air introduction passage, so that new EGR gas flowing into the intake passage downstream of the throttle valve is newly introduced. The EGR rate is attenuated early by mixing.

JP 2012-7547 A

  However, in the engine described in Patent Document 1, the fresh air introduction valve is controlled to open side and the throttle valve is controlled to close side when the engine is decelerated, but the throttle valve is being closed toward full closure, At the time of deceleration transition, sufficient negative pressure is not generated in the intake passage downstream from the throttle valve, and fresh air is not introduced into the intake passage from the fresh air introduction passage. It was not possible to make up for the new air introduced. For this reason, when the engine is decelerated from the EGR-on state, the amount of intake air taken into the combustion chamber is insufficient by the amount of EGR gas compared to when the engine is decelerated when the EGR is off, and a deceleration misfire tends to occur. In addition, the intake of the reduced amount can be compensated for by introducing fresh air from the fresh air introduction passage after the intake passage downstream of the throttle valve becomes negative pressure, and until the negative pressure is No matter how much the introduction valve is opened, the intake air cannot be supplemented with fresh air. For this reason, at the time of engine deceleration transition, the EGR rate in the combustion chamber cannot be effectively attenuated, and the engine may misfire.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to close an intake air amount adjustment valve during engine deceleration operation in an engine with a supercharger equipped with a low-pressure loop type exhaust gas recirculation device. An object of the present invention is to provide an engine control device that can compensate for a shortage of intake air amount due to inflow of exhaust gas recirculation gas remaining in an intake passage and prevent misfire in a combustion chamber.

In order to achieve the above object, an invention according to claim 1 is provided between an intake passage and an exhaust passage of an engine, and a supercharger for boosting intake air in the intake passage, and a supercharger, Intake amount adjustment for adjusting the amount of intake air flowing through the intake passage, including a compressor disposed in the intake passage, a turbine disposed in the exhaust passage, and a rotating shaft that connects the compressor and the turbine so as to be integrally rotatable. A valve, an exhaust gas recirculation passage for flowing a part of the exhaust gas discharged from the combustion chamber of the engine to the exhaust gas passage as an exhaust gas recirculation gas to the intake air passage, and exhaust gas for adjusting exhaust gas recirculation in the exhaust gas recirculation passage An exhaust gas recirculation device including a recirculation valve, and an exhaust gas recirculation passage, an inlet of which is connected to an exhaust passage downstream of the turbine, and an outlet of the exhaust gas recirculation passage connected to an intake passage upstream of the compressor; In the engine control apparatus, the control means includes an operation state detection means for detecting the operation state of the engine and a control means for controlling at least the intake air amount adjustment valve and the exhaust gas recirculation valve based on the detected operation state. When the exhaust gas recirculation valve is opened and the engine is decelerating from the state in which the intake air is boosted by the supercharger, the exhaust gas recirculation valve is controlled to be fully closed and the intake air amount adjustment valve In the process of closing the intake air amount adjustment valve, in order to compensate for the intake air amount deficient due to the inflow of exhaust gas recirculation gas into the intake passage, the exhaust air recirculation valve sets the closing speed of the intake air amount adjustment valve. The control means corrects the valve closing speed when the intake air amount adjustment valve is controlled to close when the engine is decelerating from the state where the intake air is boosted by the supercharger. Detected during engine deceleration The ratio of the amount of exhaust gas recirculation gas to the total amount of gas sucked into the combustion chamber is determined based on the operating condition to be controlled, and the intake air amount adjustment valve is controlled to a final opening degree close to full closing, and the final ratio increases as the calculated ratio increases. The purpose is to correct the final opening so that the opening becomes large.

According to the configuration of the above invention, when the exhaust gas recirculation is performed and the engine is decelerating from the supercharged state, the exhaust gas recirculation valve is controlled to be fully closed and the intake air amount adjusting valve is controlled. Is closed. Here, in the process of closing the intake air amount adjusting valve, the closing speed of the intake air amount adjusting valve is corrected, so that the amount of intake air that is deficient is compensated by the inflow of the exhaust gas recirculation gas. Further, during engine deceleration operation, the intake air amount adjustment valve is controlled to a final opening degree close to full closing, and the final opening degree is increased so that the final opening degree increases as the ratio of the amount of exhaust gas recirculation gas increases. Since the correction is made, the supplemented intake air amount is adjusted in an increasing direction as the ratio of the exhaust gas recirculation gas amount increases.

In order to achieve the above object, an invention according to claim 2 is provided between an intake passage and an exhaust passage of an engine, and a supercharger for boosting intake air in the intake passage, Intake amount adjustment for adjusting the amount of intake air flowing through the intake passage, including a compressor disposed in the intake passage, a turbine disposed in the exhaust passage, and a rotating shaft that connects the compressor and the turbine so as to be integrally rotatable. A valve, an exhaust gas recirculation passage for flowing a part of the exhaust gas discharged from the combustion chamber of the engine to the exhaust gas passage as an exhaust gas recirculation gas to the intake air passage, and exhaust gas for adjusting exhaust gas recirculation in the exhaust gas recirculation passage An exhaust gas recirculation device including a recirculation valve, and an exhaust gas recirculation passage, an inlet of which is connected to an exhaust passage downstream of the turbine, and an outlet of the exhaust gas recirculation passage connected to an intake passage upstream of the compressor; In the engine control apparatus, the control means includes an operation state detection means for detecting the operation state of the engine and a control means for controlling at least the intake air amount adjustment valve and the exhaust gas recirculation valve based on the detected operation state. When the exhaust gas recirculation valve is opened and the engine is decelerating from the state in which the intake air is boosted by the supercharger, the exhaust gas recirculation valve is controlled to be fully closed and the intake air amount adjustment valve In the process of closing the intake air amount adjustment valve, in order to compensate for the intake air amount deficient due to the inflow of exhaust gas recirculation gas into the intake passage, the exhaust air recirculation valve sets the closing speed of the intake air amount adjustment valve. The engine is corrected for the valve closing speed when the intake air amount adjustment valve is closed when the engine is decelerating from the state where the intake air is boosted by the supercharger and the engine is Inlet air downstream from the intake air amount adjustment valve A fresh air introduction passage for introducing fresh air into the air and a fresh air introduction valve for adjusting the amount of fresh air flowing through the fresh air introduction passage, and the control means has an exhaust recirculation valve opened, and When the engine is decelerating from the state in which the intake air pressure is increased by the turbocharger, the fresh air introduction valve is opened, and the fresh air introduction passage has a check that restricts the backflow of gas from the intake passage. When the engine is decelerating, the intake air amount adjustment valve is controlled to a final opening degree close to full closing, and the final opening degree is set so that the final opening degree decreases as the opening degree of the fresh air introduction valve increases. The purpose is to correct.

According to the configuration of the above invention, when the exhaust gas recirculation is performed and the engine is decelerating from the supercharged state, the exhaust gas recirculation valve is controlled to be fully closed and the intake air amount adjusting valve is controlled. Is closed. Here, in the process of closing the intake air amount adjusting valve, the closing speed of the intake air amount adjusting valve is corrected, so that the amount of intake air that is deficient is compensated by the inflow of the exhaust gas recirculation gas. In addition, when exhaust gas recirculation is performed and the engine is decelerating from a supercharged state, the fresh air introduction valve is opened, so the intake air amount adjustment valve is closed to some extent and the intake air amount adjustment valve is When negative pressure is generated in the downstream intake passage, fresh air is introduced from the fresh air introduction passage into the intake passage. Furthermore, since the check valve is provided in the fresh air introduction passage, the backflow of gas from the intake passage to the fresh air introduction passage is restricted. In addition, during engine deceleration operation, the intake air amount adjustment valve is controlled to a final opening degree close to full closing, and the final opening degree is corrected so that the final opening degree decreases as the opening degree of the fresh air introduction valve increases. Therefore, the supplemented intake air amount is adjusted to decrease as the amount of fresh air introduced into the intake passage increases.

In order to achieve the above object, according to a third aspect of the present invention, in the second aspect of the present invention, the control means is configured to control the final opening of the intake air amount adjusting valve as the engine load detected as the operating state increases. The purpose is to correct the final opening so that becomes smaller.

According to the configuration of the invention described above, in addition to the operation of the invention according to claim 2 , the final opening is corrected so that the final opening of the intake air amount adjusting valve becomes smaller as the engine load becomes higher. The intake air amount is adjusted to decrease as the engine load increases.

In order to achieve the above object, according to a fourth aspect of the present invention, in the second aspect of the present invention, the control means is configured such that the higher the intake pressure in the intake passage detected as the operating state, the higher the intake air amount adjustment valve. The purpose is to correct the final opening so that the opening becomes smaller.

According to the configuration of the above invention, in addition to the operation of the invention according to claim 2 , the final opening is corrected so that the final opening of the intake air amount adjustment valve decreases as the intake pressure in the intake passage increases. The supplemented intake air amount is adjusted to decrease as the intake air pressure increases.

According to the first aspect of the present invention, in an engine with a supercharger equipped with a low-pressure loop exhaust gas recirculation device, the intake air amount adjustment valve remains in the intake passage during the process of closing the engine during deceleration operation of the engine. In addition, the shortage of intake air due to the inflow of exhaust gas recirculation gas can be compensated to prevent misfire in the combustion chamber. Further, misfire due to insufficient intake air amount due to exhaust gas recirculation gas remaining in the intake passage during engine deceleration operation can be prevented more precisely.

According to the second aspect of the present invention, in the engine with a supercharger equipped with the low-pressure loop exhaust gas recirculation device, the intake air amount adjustment valve remains in the intake passage during the process of closing the engine during the deceleration operation of the engine. In addition, the shortage of intake air due to the inflow of exhaust gas recirculation gas can be compensated to prevent misfire in the combustion chamber. Further, the ratio of fresh air in the intake air taken into the combustion chamber can be increased, the ratio of the exhaust gas recirculation gas can be further reduced, and the intake amount shortage caused by the exhaust gas recirculation gas remaining in the intake passage can be further reduced. In addition, misfire in the combustion chamber can be prevented more reliably. Furthermore, the fresh air introduction valve can be opened even when the engine is supercharged, and a new air introduction delay due to a delay in opening the fresh air introduction valve can be avoided. Further, it is possible to prevent excessive air from being supplied to the combustion chamber during deceleration operation of the engine, to stabilize engine torque, and to prevent deterioration of engine drivability.

According to the invention described in claim 3 , in addition to the effect of the invention described in claim 2 , it is possible to more precisely prevent the drivability from being deteriorated due to the excessive amount of air during engine deceleration operation.

According to the invention described in claim 4 , in addition to the effect of the invention described in claim 2 , it is possible to more precisely prevent the drivability from being deteriorated due to the excessive amount of air during the engine deceleration operation.

The schematic block diagram which shows the engine system with a supercharger which concerns on 1st Embodiment and contains the engine EGR apparatus. The flowchart which concerns on 1st Embodiment and shows an example of the processing content of fresh air introduction control. The map referred in order to obtain | require the target opening degree of the fresh air introduction valve according to 1st Embodiment according to an engine speed and engine load. The map referred in order to obtain | require the target opening degree at the time of deceleration of the fresh air introduction valve according to 1st Embodiment according to an engine speed. The flowchart which concerns on 1st Embodiment and shows an example of the processing content of the cooperative control of the electronic throttle device with respect to control of a fresh air introduction valve. The map referred in order to obtain | require the throttle opening / closing speed according to 1st Embodiment according to an accelerator opening / closing speed. The map referred to in order to obtain | require the 1st correction coefficient according to 1st Embodiment according to an EGR rate. The map referred to in order to obtain | require the 2nd correction coefficient according to 1st Embodiment according to an engine speed. The map referred to in order to obtain | require the throttle valve closing opening degree according to 1st Embodiment according to an engine speed. The map referred to in order to obtain | require the fully-closed raising correction amount according to 1st Embodiment according to an EGR rate. The map referred in order to obtain | require the correction amount of the deceleration valve closing opening degree according to 1st Embodiment according to the opening degree of a fresh air introduction valve. According to the first embodiment, (a) throttle opening, (b) fresh air introduction valve opening, (c) intake air amount, (d) EGR rate, and (e) engine torque behavior during engine deceleration operation. The time chart which shows an example. The schematic block diagram which shows the engine system with a supercharger which concerns on 2nd Embodiment and contains the engine EGR apparatus. The flowchart which shows an example of the processing content of fresh air introduction control concerning 2nd Embodiment. The flowchart which shows only a different part from the flowchart of FIG. 5 about an example of the processing content of the cooperative control of the electronic throttle device with respect to control of a fresh air introduction valve concerning 2nd Embodiment. The map referred to in order to obtain | require the load correction coefficient according to 2nd Embodiment according to engine load. The second embodiment is similar to FIG. 12 and includes (a) throttle opening, (b) fresh air introduction valve opening, (c) intake air amount, and (d) during engine 1 deceleration operation. The time chart which shows an example of a behavior of an EGR rate and (e) engine torque.

<First Embodiment>
Hereinafter, a first embodiment of an engine control device according to the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a schematic configuration diagram showing an engine system with a supercharger including an engine exhaust gas recirculation device (EGR device) in this embodiment. This engine system includes a reciprocating engine 1. An intake passage 3 is connected to the intake port 2 of the engine 1, and an exhaust passage 5 is connected to the exhaust port 4. An air cleaner 6 is provided at the inlet of the intake passage 3. A supercharger 7 for boosting the intake air in the intake passage 3 is provided in the intake passage 3 downstream of the air cleaner 6 between the exhaust passage 5 and the intake passage 3.

  The supercharger 7 includes a compressor 8 disposed in the intake passage 3, a turbine 9 disposed in the exhaust passage 5, and a rotating shaft 10 that connects the compressor 8 and the turbine 9 so as to be integrally rotatable. The supercharger 7 rotates the turbine 9 by the exhaust gas flowing through the exhaust passage 5 and integrally rotates the compressor 8 via the rotary shaft 10 to boost the intake air in the intake passage 3, that is, perform supercharging. It is like that.

  An exhaust bypass passage 11 that bypasses the turbine 9 is provided in the exhaust passage 5 adjacent to the supercharger 7. A waste gate valve 12 is provided in the exhaust bypass passage 11. By adjusting the exhaust gas flowing through the exhaust bypass passage 11 by the waste gate valve 12, the exhaust gas flow rate supplied to the turbine 9 is adjusted, the rotational speeds of the turbine 9 and the compressor 8 are adjusted, and supercharging by the supercharger 7 is performed. The pressure is adjusted.

  In the intake passage 3, an intercooler 13 is provided between the compressor 8 of the supercharger 7 and the engine 1. The intercooler 13 is for cooling the intake air that has been pressurized by the compressor 8 to a high temperature. A surge tank 3 a is provided in the intake passage 3 between the intercooler 13 and the engine 1. An electronic throttle device 14 that is an electric throttle valve is provided in the intake passage 3 downstream of the intercooler 13 and upstream of the surge tank 3a. The electronic throttle device 14 corresponding to the intake air amount adjusting valve of the present invention includes a butterfly throttle valve 21 disposed in the intake passage 3, a DC motor 22 for opening and closing the throttle valve 21, and a throttle valve 21. And a throttle sensor 23 for detecting the opening (throttle opening) TA. The electronic throttle device 14 is configured such that the throttle valve 21 is driven to open and close by a DC motor 22 in accordance with the operation of an accelerator pedal 26 by a driver, and the opening degree is adjusted. The exhaust passage 5 on the downstream side of the turbine 9 is provided with a catalytic converter 15 as an exhaust catalyst for purifying exhaust.

  The engine 1 is provided with an injector 25 for injecting and supplying fuel to the combustion chamber 16. Fuel is supplied to the injector 25 from a fuel tank (not shown). The injector 25 corresponds to an example of a fuel supply unit. The engine 1 is provided with a spark plug 29 corresponding to each cylinder. Each spark plug 29 is ignited by receiving a high voltage output from the igniter 30. The ignition timing of each spark plug 29 is determined by the high voltage output timing from the igniter 30. The spark plug 29 and the igniter 30 constitute an ignition device.

  In this embodiment, the EGR device for realizing a large amount of EGR is an exhaust gas recirculation passage for flowing a part of the exhaust discharged from the combustion chamber 16 of the engine 1 to the exhaust passage 5 to the intake passage 3 and returning it to the combustion chamber 16. (EGR passage) 17 and an exhaust gas recirculation valve (EGR valve) 18 provided in the EGR passage 17 in order to adjust the exhaust gas flow rate (EGR flow rate) in the EGR passage 17. This EGR device is configured as a low-pressure loop type, and the EGR passage 17 is provided between the exhaust passage 5 downstream of the catalytic converter 15 and the intake passage 3 upstream of the compressor 8. That is, in order to flow part of the exhaust gas flowing through the exhaust passage 5 as EGR gas to the intake passage 3 through the EGR passage 17 and return to the combustion chamber 16, the outlet 17 a of the EGR passage 17 is connected to the intake passage 3 upstream of the compressor 8. Connected to. Further, the inlet 17 b of the EGR passage 17 is connected to the exhaust passage 5 downstream from the catalytic converter 15.

  The EGR passage 17 is provided with an EGR cooler 20 for cooling the EGR gas flowing through the passage 17. In this embodiment, the EGR valve 18 is disposed in the EGR passage 17 downstream of the EGR cooler 20.

  As shown in FIG. 1, the EGR valve 18 is configured as a poppet valve and as an electric valve. That is, the EGR valve 18 includes a valve body 32 that is driven by the DC motor 31. The valve body 32 has a substantially conical shape, and is provided so as to be seated on a valve seat 33 provided in the EGR passage 17. The DC motor 31 includes an output shaft 34 that is configured to be able to reciprocate (stroke) in a straight line. A valve body 32 is fixed to the tip of the output shaft 34. The output shaft 34 is supported by a housing constituting the EGR passage 17 via a bearing 35. The opening degree of the valve body 32 with respect to the valve seat 33 is adjusted by moving the output shaft 34 of the DC motor 31 in a stroke. The output shaft 34 of the EGR valve 18 is provided so as to be capable of stroke movement from a fully closed state in which the valve body 32 is seated on the valve seat 33 to a fully open state in which the valve body 32 contacts the bearing 35. In this embodiment, in order to realize a large amount of EGR, the opening area of the valve seat 33 is enlarged as compared with the conventional technique. Accordingly, the valve body 32 is enlarged.

  As shown in FIG. 1, in this embodiment, a fresh air introduction passage 41 is provided in order to introduce fresh air into the surge tank 3 a downstream from the electronic throttle device 14. The fresh air introduction passage 41 has an inlet 41 a downstream of the air cleaner 6 and connected to the intake passage 3 upstream of the outlet 17 a of the EGR passage 17, and its outlet 41 b is connected to the intake passage 3 downstream of the electronic throttle device 14. Connected. In the middle of the fresh air introduction passage 41, an electric fresh air introduction valve 42 corresponding to the fresh air flow control valve of the present invention is provided. The fresh air introduction valve 42 is configured such that the opening degree of the valve body with respect to the valve seat is adjusted by driving the valve body with a solenoid. By adjusting the opening degree of the fresh air introduction valve 42, the flow rate of fresh air flowing from the fresh air introduction passage 41 to the surge tank 3a is adjusted.

  In this embodiment, in order to execute fuel injection control, ignition timing control, intake air amount control, EGR control, fresh air flow rate control, and the like according to the operating state of the engine 1, the injector 25, the igniter 30, and the electronic throttle device 14 are executed. The DC motor 22, the DC motor 31 of the EGR valve 18, and the fresh air introduction valve 42 are each controlled by an electronic control unit (ECU) 50 according to the operating state of the engine 1. The ECU 50 stores in advance a central processing unit (CPU), a predetermined control program and the like, various memories for temporarily storing a calculation result of the CPU, and the like, an external input circuit connected to these parts, and an external And an output circuit. The ECU 50 corresponds to an example of a control unit of the present invention. The external output circuit is connected to the igniter 30, the injector 25, the DC motors 22 and 31, and the fresh air introduction valve 42. Various sensors 27 and 51 to 55 corresponding to an example of the operation state detecting means of the present invention for detecting the operation state of the engine 1 including the throttle sensor 23 are connected to the external input circuit, and various engine signals are inputted. It has become so.

  Here, in addition to the throttle sensor 23, an accelerator sensor 27, an intake pressure sensor 51, a rotation speed sensor 52, a water temperature sensor 53, an air flow meter 54, and an air-fuel ratio sensor 55 are provided as various sensors. The accelerator sensor 27 detects an accelerator opening ACC that is an operation amount of the accelerator pedal 26. The accelerator pedal 26 corresponds to an example of an operation unit for operating the operation of the engine 1. The intake pressure sensor 51 detects the intake pressure PM in the surge tank 3a. That is, the intake pressure sensor 51 corresponds to an example of an intake pressure detection means, and detects the intake pressure PM in the intake passage 3 (surge tank 3a) downstream from the position where EGR gas flows from the EGR passage 17 into the intake passage 3. It has become. The rotational speed sensor 52 detects the rotational angle (crank angle) of the crack shaft 1a of the engine 1 and detects the change in the crank angle as the rotational speed (engine rotational speed) NE of the engine 1. The water temperature sensor 53 detects the cooling water temperature THW of the engine 1. That is, the water temperature sensor 53 corresponds to an example of a temperature state detection unit, and detects the cooling water temperature THW indicating the temperature state of the engine 1. The air flow meter 54 corresponds to an example of an intake air amount measuring unit, and detects an intake air amount Ga flowing through the intake passage 3 immediately downstream of the air cleaner 6. The air-fuel ratio sensor 55 is provided in the exhaust passage 5 immediately upstream of the catalytic converter 15, and detects the air-fuel ratio A / F in the exhaust.

  In this embodiment, the ECU 50 controls to open the EGR valve 18 in order to execute EGR in accordance with the operating state of the engine 1, that is, to recirculate the EGR gas, in the entire operation region of the engine 1. It has become. On the other hand, when the engine 1 is decelerated, the ECU 50 controls the EGR valve 18 to be fully closed so as not to execute EGR, that is, to block the recirculation of the EGR gas. Further, the ECU 50 controls the fresh air introduction valve 42 in accordance with the control of the EGR valve 18. That is, when the EGR valve 18 is opened, the ECU 50 basically controls the fresh air introduction valve 42 to be fully closed. On the other hand, when the EGR valve 18 is controlled to be fully closed, the ECU 50 opens the fresh air introduction valve 42.

  Here, even if the EGR valve 18 is closed when the engine 1 is decelerated, the path of the intake passage 3 from the outlet 17a of the EGR passage 17 to the electronic throttle device 14 is relatively long, so that EGR gas remains there. In some cases, the remaining EGR gas flows into the combustion chamber 16, which may cause a deceleration misfire in the engine 1. Therefore, in this embodiment, when the EGR valve 18 is opened (in a state in which EGR is being executed) and the engine 1 is decelerating from the state in which the intake air is boosted by the supercharger 7, The ECU 50 executes the following control in order to coordinate the control of the electronic throttle device 14 (throttle valve 21) and the fresh air introduction valve 42 in order to compensate for the intake air amount deficient due to the inflow of EGR gas remaining in the passage 3. It is supposed to be.

  FIG. 2 is a flowchart showing an example of processing contents of fresh air introduction control executed by the ECU 50. When the process proceeds to this routine, in step 100, the ECU 50 takes in the engine rotational speed NE, the engine load KL, and the intake air amount Ga. The ECU 50 can take in the engine rotation speed NE based on the detection value of the rotation speed sensor 52. The ECU 50 can determine the engine load KL based on the engine rotation speed NE and the detected values of the intake pressure sensor 51. Further, the ECU 50 can obtain the intake air amount Ga based on the detection value of the air flow meter 54.

  Next, at step 110, the ECU 50 takes in the EGR rate Eegr. Here, the EGR rate Eegr means the ratio of the amount of EGR gas to the total amount of gas sucked into the combustion chamber 16. The ECU 50 can separately obtain the EGR rate Eegr based on the intake air amount Ga, the engine rotational speed NE, and the engine load KL.

  Next, in step 120, the ECU 50 determines whether or not the engine 1 is in steady operation or acceleration operation. The ECU 50 can make this determination based on, for example, the accelerator opening ACC and the engine speed NE. If the determination result is affirmative, the ECU 50 proceeds to step 130. If this determination result is negative, the ECU 50 proceeds to step 180 assuming that the engine 1 is decelerating or idling.

  In step 130, the ECU 50 determines whether or not the engine load KL is higher than a predetermined value K1 corresponding to a high load. As this predetermined value K1, for example, “80%” can be applied. If the determination result is affirmative, the ECU 50 proceeds to step 140 assuming that the engine 1 is in a supercharging region (an operating region in which the supercharger 7 is operating). If the determination result is negative, the ECU 50 proceeds to step 190 assuming that the engine 1 is in a non-supercharged region (an operating region where the supercharger 7 is not operating).

  In step 140, the ECU 50 sets the target opening degree TCAV of the fresh air introduction valve 42 to “0”.

  Next, in step 150, the ECU 50 determines whether or not EGR is on. That is, the ECU 50 determines whether or not EGR control is being executed. If this determination result is negative, the ECU 50 proceeds to step 170 as it is. If the determination result is affirmative, the ECU 50 proceeds to step 160.

  In step 160, the ECU 50 sets the EGR execution flag XEGR to “1”, and the process proceeds to step 170. The flag XEGR is set to “1” when the EGR control is being executed, and to “0” when the EGR control is not being executed.

  Then, in step 170 after shifting from step 150 or step 160, the ECU 50 controls the fresh air introduction valve 42 to the target opening degree TCAV and returns the process to step 100.

  On the other hand, in step 180, the ECU 50 determines whether or not the EGR execution flag XEGR is “1”. If this determination is negative, the ECU 50 proceeds to step 190 assuming that the scavenging of the EGR gas in the intake passage 3 has been completed. If this determination result is affirmative, the ECU 50 proceeds to step 200 assuming that EGR gas remains in the intake passage 3.

  In step 190 after shifting from step 130 or step 180, the ECU 50 determines the target opening degree TCAV corresponding to the engine speed NE and the engine load KL, and then shifts the processing to step 150. The ECU 50 can obtain the target opening degree TCAV corresponding to the engine speed NE and the engine load KL by referring to the map shown in FIG. In this map, the target opening degree TCAV is set to increase as the engine rotational speed NE increases and the engine load KL increases.

  In step 200, the ECU 50 determines a deceleration target opening Tcavne corresponding to the engine speed NE. The ECU 50 can obtain the deceleration target opening degree Tcavne according to the engine speed NE by referring to the map shown in FIG. In this map, the deceleration target opening degree Tcavne is set to increase as the engine speed NE increases.

  Next, at step 210, the ECU 50 sets the deceleration target opening Tcavne as the target opening TCAV.

  Next, at step 220, the ECU 50 determines whether or not the EGR rate Eegr is lower than a predetermined value A1. If this determination result is negative, the ECU 50 proceeds to step 170 assuming that EGR gas remains in the intake passage 3. If this determination result is affirmative, the ECU 50 proceeds to step 230 assuming that the scavenging of the EGR gas in the intake passage 3 has been completed.

  In step 230, the ECU 50 returns the EGR execution flag XEGR to “0”, and the process proceeds to step 170.

  According to the above control, the ECU 50 controls the fresh air introduction valve 42 according to the operating state of the engine 1, thereby introducing fresh air into the intake passage 3 (including the surge tank 3 a) downstream from the throttle valve 21. It is supposed to be.

  FIG. 5 is a flowchart showing an example of the processing contents of the cooperative control of the electronic throttle device 14 executed by the ECU 50 for the control of the fresh air introduction valve 42 during the deceleration operation of the engine 1. When the processing shifts to this routine, first, at step 300, the ECU 50 takes in the accelerator opening degree ACC and the accelerator opening / closing speed ΔACC / 4ms. The ECU 50 takes in the accelerator opening ACC based on the detection value of the accelerator sensor 27. Further, the ECU 50 can obtain the accelerator opening / closing speed ΔACC / 4 ms from the difference between the current accelerator opening ACC and the previous accelerator opening ACC, which are taken in every “4 ms”. Here, when the accelerator pedal 26 is depressed, the accelerator opening / closing speed ΔACC / 4 ms is a positive value, and when the accelerator pedal 26 is decelerated, the accelerator opening / closing speed ΔACC / 4 ms is a negative value.

  Next, at step 310, the ECU 50 takes in the engine rotational speed NE, the engine load KL, and the intake air amount Ga. The ECU 50 can take in the engine rotation speed NE based on the detection value of the rotation speed sensor 52. Further, the ECU 50 can obtain the engine load KL based on the engine rotation speed NE and the detected values of the intake pressure sensor 51. Further, the ECU 50 can take in the intake air amount Ga based on the detection value of the air flow meter 54.

  Next, at step 320, the ECU 50 takes in the EGR rate Eegr. The ECU 50 can separately obtain the EGR rate Eegr based on the intake air amount Ga, the engine rotational speed NE, and the engine load KL.

  Next, at step 330, the ECU 50 obtains a throttle opening / closing speed ΔTA / 4ms corresponding to the accelerator opening / closing speed ΔACC / 4ms. The ECU 50 can obtain the throttle opening / closing speed ΔTA / 4 ms corresponding to the accelerator opening / closing speed ΔACC / 4 ms by referring to the map shown in FIG. In this map, as the accelerator opening / closing speed ΔACC / 4 ms increases from a negative value to a positive value, the throttle opening / closing speed ΔTA / 4 ms is linear between the maximum valve closing speed and the maximum valve opening speed ΔTAmax / 4 ms. Is set to increase. In this embodiment, the throttle opening / closing speed ΔTA / 4 ms corresponds to an example of the valve closing speed and the valve opening speed of the throttle valve 21 of the present invention.

  Next, in step 340, the ECU 50 obtains a first correction coefficient KΔTA related to the throttle opening / closing speed ΔTA / 4 ms corresponding to the EGR rate Eegr. The ECU 50 can obtain the first correction coefficient KΔTA corresponding to the EGR rate Eegr by referring to the map shown in FIG. In this map, when the throttle opening / closing speed ΔTA / 4 ms is a negative value (in the case of deceleration), the first correction coefficient KΔTA is between “1.0” and the minimum value as the EGR rate Eegr increases. It is set to decrease linearly. This means a setting for slowing down the throttle opening / closing speed ΔTA / 4 ms when the valve is closed.

  Next, at step 350, the ECU 50 obtains a second correction coefficient KΔTANE relating to the throttle opening / closing speed ΔTA according to the engine rotational speed NE. The ECU 50 can obtain the second correction coefficient KΔTANE corresponding to the engine speed NE by referring to the map shown in FIG. In this map, when the throttle opening / closing speed ΔTA / 4 ms is a negative value (in the case of deceleration), the second correction coefficient KΔTANE is between “1.0” and the minimum value as the engine speed NE increases. Is set to decrease linearly. This means a setting for slowing down the throttle opening / closing speed ΔTA / 4 ms when the valve is closed.

Next, in step 360, the ECU 50 obtains a corrected throttle opening / closing speed ΔKTA / 4 ms. The ECU 50 can obtain the corrected throttle opening / closing speed ΔKTA / 4 ms according to the following equation (1). Here, the corrected throttle opening / closing speed ΔKTA / 4 ms is
Applicable when the EGR valve 18 is opened (when EGR control is being executed) and when the engine 1 is decelerating from a state where the intake air is boosted by the turbocharger 7 (at the time of supercharging). The engine 1 is decelerated from the state in which the EGR valve 18 is closed (when EGR control is not executed) and the intake air is boosted by the supercharger 7 (at the time of supercharging). This is corrected with respect to the throttle opening / closing speed ΔTA / 4 ms applied during operation.
ΔKTA / 4 ms = ΔTA / 4 ms * KΔTA * KΔTANE (1)

  Next, in step 370, the ECU 50 determines whether or not the obtained corrected throttle opening / closing speed ΔKTA / 4ms is smaller than the maximum valve closing speed ΔTAmax / 4ms. If the determination result is negative, the ECU 50 proceeds to step 380. If the determination result is affirmative, the ECU 50 proceeds to step 390.

  In step 380, the ECU 50 sets the maximum valve closing speed ΔTAmax / 4ms as the corrected throttle opening / closing speed ΔKTA / 4ms, and the process proceeds to step 390.

  Shifting from step 370 or step 380, in step 390, the ECU 50 obtains a target throttle opening degree TTA corresponding to the accelerator opening degree ACC. The ECU 50 can obtain the target throttle opening degree TTA corresponding to the accelerator opening degree ACC by referring to a predetermined map.

  Next, at step 400, the ECU 50 obtains a throttle valve closing degree TAoff serving as a deceleration reference according to the engine speed NE. The ECU 50 can obtain the throttle valve closing degree TAoff corresponding to the engine speed NE by referring to the map shown in FIG. In this map, the throttle valve closing degree TAoff is set so as to increase linearly from the minimum value as the engine speed NE increases. In this embodiment, the throttle valve closing degree TAoff corresponds to an example of the final opening degree of the present invention.

  Next, at step 410, the ECU 50 takes in the throttle opening degree TA based on the detection value of the throttle sensor 23.

  Next, at step 420, the ECU 50 calculates a fully closed raising correction amount KTAoff1 during deceleration according to the EGR rate Eegr. The ECU 50 can obtain the fully closed raising correction amount KTAoff1 corresponding to the EGR rate Eegr by referring to the map shown in FIG. In this map, the correction amount KTAoff1 is set so as to increase linearly from “0” as the EGR rate Eegr increases. This means a setting for correcting the throttle valve closing degree TAoff so that the throttle valve closing degree TAoff increases as the EGR rate Eegr increases.

  Next, in step 430, the ECU 50 takes in the actual opening degree Ecav of the fresh air introduction valve 42. The ECU 50 can take in the opening degree Ecav based on a command value for the fresh air introduction valve 42.

  Next, at step 440, the ECU 50 can obtain the correction amount KTAoff2 of the deceleration valve closing degree corresponding to the opening degree Ecav of the fresh air introduction valve. The ECU 50 can obtain the correction amount KTAoff2 corresponding to the opening degree Ecav by referring to the map shown in FIG. In this map, the correction amount KTAoff2 is set to linearly increase from “0” as the opening degree Ecav increases. This means a setting for correcting the throttle valve closing degree TAoff so that the throttle valve closing degree TAoff becomes smaller as the opening degree Ecav of the fresh air introduction valve 42 becomes larger.

Next, in step 450, the ECU 50 obtains a corrected throttle valve opening degree TAOFF. The ECU 50 can obtain the corrected throttle valve opening degree TAOFF according to the following equation (2).
TAOFF = TAoff + KTAoff1-KTAoff2 (2)

  Next, in step 460. The ECU 5 determines whether or not the target throttle opening degree TTA is equal to or larger than the corrected throttle valve opening degree TAOFF. If this determination result is negative, the ECU 50 proceeds to step 470, and if this determination result is affirmative, the ECU 50 proceeds to step 480.

  In step 470, the ECU 50 sets the corrected throttle valve closing degree TAOFF as the target throttle opening degree TTA, and the process proceeds to step 480.

  After step 460 or step 470, in step 480, the ECU 50 determines whether or not the target throttle opening degree TTA is smaller than the throttle opening degree TA. If this determination result is affirmative, the ECU 50 proceeds to step 490, and if this determination result is negative, the ECU 50 proceeds to step 500.

  In step 490, the ECU 50 controls the electronic throttle device 14 so as to follow the target throttle opening TTA at a negative correction throttle opening / closing speed −ΔKTA / 4 ms, and the process returns to step 300. That is, the ECU 50 closes the throttle valve 21 at a speed slower than the normal valve closing speed when the throttle valve 21 is closed by a corrected throttle opening / closing speed ΔKTA / 4 ms.

  On the other hand, in step 500, the ECU 50 determines whether or not the target throttle opening degree TTA is larger than the throttle opening degree TA. If the determination result is negative, the ECU 50 proceeds to step 510. If the determination result is affirmative, the ECU 50 proceeds to step 520.

  In step 510, the ECU 50 maintains the throttle opening degree TA at the target throttle opening degree TTA, and returns the process to step 100. That is, the ECU 50 controls the electronic throttle device 14 so that the throttle opening degree TA maintains the target throttle opening degree TTA.

  On the other hand, in step 520, the ECU 50 controls the electronic throttle device 14 to follow the target throttle opening degree TTA at a positive corrected throttle opening / closing speed + ΔKTA / 4 ms, and returns the process to step 300. That is, the ECU 50 opens the throttle valve 21 at a speed higher than the normal valve opening speed when the throttle valve 21 is opened by the corrected throttle opening / closing speed ΔKTA / 4 ms.

  According to the engine control apparatus in this embodiment described above, when EGR is performed and the engine 1 is decelerating from the supercharged state, the EGR valve 18 is controlled to be fully closed. At the same time, the electronic throttle device 14 (throttle valve 21) is controlled to close. Here, in the process in which the throttle valve 21 is closed, the valve closing speed of the throttle valve 21 is corrected. Therefore, the intake amount that is deficient due to the inflow of EGR gas is compensated by the correction amount. For this reason, in the engine 1 having the supercharger 7 equipped with the low-pressure loop type EGR device, the EGR gas remaining in the intake passage 3 during the process of closing the throttle valve 21 during the deceleration operation of the engine 1 is reduced. A shortage of intake air due to inflow can be compensated for and misfire in the combustion chamber 16 can be prevented.

  In this embodiment, when EGR is performed and the engine 1 is decelerating from the supercharged state, the fresh air introduction valve 42 is opened, so the throttle valve 21 is closed to some extent and the throttle valve When a negative pressure is generated in the intake passage 3 downstream of the intake passage 21, fresh air is introduced from the fresh air introduction passage 41 into the intake passage 3. For this reason, the ratio of fresh air in the intake air taken into the combustion chamber 16 can be increased, the EGR rate can be further reduced, and the shortage of intake air caused by the residual EGR gas can be further compensated for in the combustion chamber 16. Misfires can be prevented more reliably.

  In this embodiment, when the engine 1 is decelerated, the throttle opening / closing speed ΔTA / 4 ms is corrected so that the valve closing speed of the throttle valve 21 decreases as the EGR rate Eegr increases. The rate Eegr increases as the rate Eegr increases. Here, if the throttle opening degree TA is the same, the intake air amount Ga decreases as the EGR rate Eegr increases. While the engine 1 is decelerating, the amount of air passing through the throttle valve 21 and the residual EGR amount are large, so that the shortage of intake air due to the residual EGR gas cannot be compensated. Therefore, in this embodiment, during the deceleration operation, the valve closing speed of the throttle valve 21 is decreased to increase the amount of air passing through the throttle valve 21 as much as possible. As a result, it is possible to more accurately prevent misfire due to insufficient intake air amount due to residual EGR gas during deceleration operation.

  In this embodiment, when the engine 1 is decelerated, the throttle opening / closing speed ΔTA / 4 ms is corrected so that the higher the engine speed NE, the slower the valve closing speed of the throttle valve 21. The engine speed NE is adjusted to increase as the engine speed NE increases. This is to take measures against the higher speed of the engine load KL at the time of deceleration as the engine rotational speed NE is higher, and the influence of the shortage of intake air due to the residual EGR gas tends to occur. As a result, it is possible to more accurately prevent misfire due to insufficient intake air amount due to residual EGR gas during deceleration operation.

  In this embodiment, during the deceleration operation of the engine 1, the throttle valve 21 is controlled to the throttle valve closing degree TAOFF close to full closing, and the throttle valve closing degree TAOFF increases as the EGR rate Eegr increases. Thus, the throttle valve closing degree TAOFF is corrected so that the supplemented intake air amount is adjusted to increase as the EGR rate Eegr increases. As a result, it is possible to more accurately prevent misfire due to insufficient intake air amount due to residual EGR gas during deceleration operation.

  FIG. 12 shows (a) throttle opening degree TA, (b) opening degree Ecav of fresh air introduction valve 42, (c) intake air amount Ga, (d) EGR rate Eegr, and (e) engine during deceleration operation of engine 1. An example of torque behavior is shown by a time chart. In FIG. 12A, the thick line indicates the throttle opening degree TA during the deceleration operation from the EGR-on state, according to the present embodiment. The broken line indicates the throttle opening degree TA during the deceleration operation from EGR off. A two-dot chain line relates to the conventional example, and indicates the throttle opening degree TA during the deceleration operation from EGR ON. In FIG. 12C, the thick line indicates the intake air amount Ga during the deceleration operation from the EGR-on state, according to the present embodiment. A broken line indicates the intake air amount Ga during the deceleration operation from EGR off. A two-dot chain line relates to the conventional example, and indicates the intake air amount Ga during deceleration operation from EGR ON. In FIG.12 (e), a thick line is related to this embodiment, and shows the engine torque at the time of the deceleration driving | operation from EGR ON. The broken line indicates the engine torque during the deceleration operation from EGR off. The two-dot chain line relates to the conventional example, and shows the engine torque during the deceleration operation from EGR ON.

  In FIG. 12, when the throttle opening degree TA starts to decrease at time t1, the opening degree Ecav of the fresh air introduction valve 42 starts to increase. Thereafter, at time t2, as indicated by the thick line, the intake air amount Ga and the engine torque start to decrease. Thereafter, at time t5, as indicated by the thick line, the throttle opening degree TA reaches a certain closed valve opening, which is almost fully closed, but at the time t4 immediately before that, the intake air amount Ga is minimum, as indicated by the thick line. The value is constant, and the engine torque is constant at “0”. Further, at time t6, the opening degree Ecav of the fresh air introduction valve 42 reaches the maximum value, and thereafter starts to decrease, and reaches full closure at time t7. A portion indicated by hatching in FIG. 12B indicates a portion where the fresh air response is insufficient even when the fresh air introduction valve 42 is opened during the deceleration operation of the engine 1 from the EGR-on state. On the other hand, in this embodiment, since the valve closing speed of the throttle valve 21 is corrected so as to be slower than the conventional example by the amount indicated by hatching in FIG. 12A, the hatching in FIG. The intake air amount Ga is corrected by the amount indicated by, and the engine torque is corrected by the amount indicated by hatching in FIG. As a result, as shown in FIG. 12 (d), the EGR rate Eegr can be kept constant between times t1 and t6 without increasing. As a result, it is possible to prevent misfire due to insufficient intake air amount when the engine 1 is decelerated.

Second Embodiment
Next, a second embodiment of the engine control device according to the present invention will be described in detail with reference to the drawings.

  In each embodiment described below, the same components as those in the first embodiment are denoted by the same reference numerals, description thereof is omitted, and different points are mainly described.

  This embodiment is different from the first embodiment in terms of the configuration related to the fresh air introduction valve 42 and the contents of the deceleration control for coordinating the control of the electronic throttle device 14 (throttle valve 21) and the fresh air introduction valve 42. The configuration is different.

  FIG. 13 is a schematic configuration diagram showing an engine system with a supercharger including an engine EGR device in this embodiment. In this embodiment, as shown in FIG. 13, a check valve 43 for preventing a backflow of gas in the fresh air introduction passage 41 is provided downstream of the fresh air introduction valve 42 in FIG. The configuration is different from the engine system.

  FIG. 14 is a flowchart showing an example of processing contents of fresh air introduction control executed by the ECU 50. In this embodiment, since the check valve 43 is provided in the fresh air introduction passage 41, the flowchart of FIG. 14 is different from the flowchart of FIG. 2 in that the processing of step 130 and step 140 in the flowchart of FIG. 2 is omitted. The configuration is different. That is, in FIG. 14, step 190 is provided between step 120 and step 150 instead of omitting step 130 and step 140.

  FIG. 15 shows only a part different from the flowchart of FIG. 5 with respect to an example of the processing contents of the cooperative control of the electronic throttle device 14 executed by the ECU 50 in accordance with the control of the fresh air introduction valve 42 when the engine 1 is decelerated. As shown in FIG. 15, in this embodiment, the configuration between step 440 and step 450 in the flowchart in FIG. 5 is different from the flowchart in FIG. 5. That is, as shown in FIG. 15, after executing the process of step 440, in step 600, the ECU 50 obtains a load correction coefficient KKL corresponding to the engine load KL. The ECU 50 can obtain the load correction coefficient KKL corresponding to the engine load KL by referring to the map shown in FIG. In this map, the load correction coefficient KKL is constant at a predetermined value in a region where the engine load KL is low, decreases toward “0” as the engine load KL increases to a medium level, and in a region where the engine load KL is high, “ It is set to be constant at “0”.

  Next, in step 610, the ECU 50 sets the corrected correction amount KTAOFF2 by multiplying the correction amount KTAoff2 of the deceleration valve opening obtained in step 440 by the load correction coefficient KKL. This means a setting for correcting the throttle valve closing degree TAOFF so that the throttle valve closing degree TAOFF becomes smaller as the engine load KL becomes higher.

In step 450, the ECU 50 obtains the corrected throttle valve opening degree TAOFF by applying the corrected correction amount KTAOFF2 to the following equation (3).
TAOFF = TAoff + KTAoff1-KTAOFF2 (3)

  The engine control apparatus according to this embodiment described above has the following effects in addition to the effects of the first embodiment. That is, since the check valve 43 is provided in the fresh air introduction passage 41, the backflow of gas from the intake passage 3 to the fresh air introduction passage 41 is restricted. Therefore, the fresh air introduction valve 42 can be opened even when the engine 1 is supercharged, and a fresh air introduction delay due to a delay in opening the fresh air introduction valve 42 can be avoided.

  In this embodiment, when the engine 1 is decelerating, the throttle valve 21 is controlled to the throttle valve closing degree TAOFF close to full closing, and the throttle valve closing is increased as the opening degree of the fresh air introduction valve 42 is increased. Since the throttle valve closing degree TAOFF is corrected so that the opening degree TAOFF becomes smaller, the supplemented intake air amount Ga is adjusted in a decreasing direction as the fresh air amount introduced into the intake passage 3 increases. As a result, it is possible to prevent the air from being excessively supplied to the combustion chamber 16 during the deceleration operation of the engine 1, to stabilize the engine torque, and to prevent deterioration of the drivability of the engine 1. it can.

  In this embodiment, since the throttle valve closing degree TAOFF is corrected so that the throttle valve closing degree TAOFF becomes smaller as the engine load KL becomes higher, the supplemented intake air amount Ga decreases as the engine load KL becomes higher. Adjusted in the direction. This is to take measures against the fact that the air intake amount Ga passing through the throttle valve 21 increases as the engine load KL increases, so that air is excessively supplied to the combustion chamber 16. As a result, it is possible to prevent the deterioration of drivability due to an excessive amount of air during deceleration operation more precisely.

  FIG. 17 is similar to FIG. 12 and shows (a) throttle opening degree TA, (b) opening degree Ecav of fresh air introduction valve 42, (c) intake air amount Ga, (d An example of the behavior of EGR rate Eegr and (e) engine torque is shown by a time chart. This time chart is different from the time chart of FIG. 12 in terms of the behavior of the throttle opening TA shown by a thick line in FIG. 17A and the behavior of the opening Ecav of the fresh air introduction valve 42 shown in FIG. Different. In particular, in this embodiment, since the check valve 43 is provided on the downstream side of the fresh air introduction valve 42, as shown in FIG. 17B, the opening degree Ecav of the fresh air introduction valve 42 is set at time t1. Thus, even if the throttle opening degree TA starts to decrease, the throttle valve TA is kept open at a certain opening degree, and as shown in FIG. 17 (d), at the time t6, the EGR rate Eegr starts decreasing at the same time. Ecav is starting to decrease. This is because the check valve 43 is provided in the fresh air introduction passage 41 so that the gas does not flow back from the intake passage 3 to the fresh air introduction passage 41 regardless of when the engine 1 is supercharged or decelerated. The fresh air introduction valve 42 is kept open from before the deceleration operation to the completion of the deceleration operation, thereby avoiding a new air introduction delay due to a delay in opening the fresh air introduction valve 42.

  Note that the present invention is not limited to the above-described embodiments, and a part of the configuration can be changed as appropriate without departing from the spirit of the invention.

  For example, in the second embodiment, the throttle valve closing degree TAOFF is corrected so that the throttle valve closing degree TAOFF decreases as the engine load KL increases. However, as the intake pressure PM increases, the throttle valve closing degree TAOFF decreases. It is also possible to correct the throttle valve closing degree TAOFF so that the valve closing degree TAOFF becomes smaller. Thereby, the supplemented intake air amount Ga is adjusted in a decreasing direction as the intake pressure PM increases. This is to take measures against the fact that the intake air amount Ga passing through the throttle valve 21 increases as the intake pressure PM increases, so that air is excessively supplied to the combustion chamber 16. As a result, it is possible to prevent the deterioration of drivability due to an excessive amount of air during deceleration operation more precisely.

  The present invention can be used for an engine with a supercharger equipped with a low-pressure loop type EGR device.

1 Engine 2 Intake Port 3 Intake Passage 3a Surge Tank 4 Exhaust Port 5 Exhaust Passage 7 Supercharger 8 Compressor 9 Turbine 9
10 Rotating shaft 14 Electronic throttle device 16 Combustion chamber 17 EGR passage (exhaust gas recirculation passage)
17a outlet 17b inlet 18 EGR valve (exhaust gas recirculation valve)
21 Throttle valve 23 Throttle sensor (operating state detection means)
27 Accelerator sensor (operating state detection means)
41 Fresh air introduction passage 42 Fresh air introduction valve 43 Check valve 50 ECU (control means)
51 Intake pressure sensor (operating state detection means)
52 Rotational speed sensor (Operating state detection means)
53 Water temperature sensor (Operating state detection means)
54 Air flow meter (Operating state detection means)
55 Air-fuel ratio sensor (operating state detection means)
ΔTA / 4ms Throttle opening / closing speed (valve closing speed)
ΔKTA / 4ms corrected throttle opening / closing speed (valve closing speed)
TAoff Throttle valve opening (final opening) that serves as a deceleration reference
Throttle valve closing after TAOFF correction (final opening)

Claims (4)

A turbocharger provided between an intake passage and an exhaust passage of the engine for boosting intake air in the intake passage;
The supercharger includes a compressor disposed in the intake passage, a turbine disposed in the exhaust passage, and a rotation shaft that connects the compressor and the turbine so as to be integrally rotatable.
An intake air amount adjusting valve for adjusting an intake air amount flowing through the intake passage;
For adjusting an exhaust gas recirculation in the exhaust gas recirculation passage, an exhaust gas recirculation passage for flowing a part of the exhaust gas discharged from the engine combustion chamber to the exhaust gas passage as an exhaust gas recirculation gas to the intake passage and recirculating to the combustion chamber An exhaust gas recirculation device including an exhaust gas recirculation valve of
The exhaust gas recirculation passage has an inlet connected to the exhaust passage downstream of the turbine and an outlet connected to the intake passage upstream of the compressor;
An operating state detecting means for detecting the operating state of the engine;
In an engine control device comprising: control means for controlling at least the intake air amount adjusting valve and the exhaust gas recirculation valve based on the detected operating state;
The control means turns the exhaust gas recirculation valve to a fully closed state when the exhaust gas recirculation valve is opened and the engine is decelerating from a state where the intake air is boosted by the supercharger. In order to compensate for the intake amount deficient due to the inflow of the exhaust gas recirculation gas into the intake passage in the process of closing the intake air amount adjusting valve and closing the intake air amount adjusting valve. The closing speed of the intake air amount adjusting valve is set so that the intake air amount adjusting valve is at a time when the engine is decelerating from the state where the exhaust gas recirculation valve is closed and the intake air is boosted by the supercharger. For the valve closing speed when the valve closing control is performed,
The control means obtains a ratio of the amount of the exhaust recirculation gas to the total amount of gas sucked into the combustion chamber based on the detected operating state during the deceleration operation of the engine, and fully closes the intake air amount adjustment valve. And controlling the final opening so that the final opening increases as the calculated ratio increases. A turbocharger provided between an intake passage and an exhaust passage of the engine for boosting intake air in the intake passage;
The supercharger includes a compressor disposed in the intake passage, a turbine disposed in the exhaust passage, and a rotation shaft that connects the compressor and the turbine so as to be integrally rotatable.
An intake air amount adjusting valve for adjusting an intake air amount flowing through the intake passage;
For adjusting an exhaust gas recirculation in the exhaust gas recirculation passage, an exhaust gas recirculation passage for flowing a part of the exhaust gas discharged from the engine combustion chamber to the exhaust gas passage as an exhaust gas recirculation gas to the intake passage and recirculating to the combustion chamber An exhaust gas recirculation device including an exhaust gas recirculation valve of
The exhaust gas recirculation passage has an inlet connected to the exhaust passage downstream of the turbine and an outlet connected to the intake passage upstream of the compressor;
An operating state detecting means for detecting the operating state of the engine;
In an engine control device comprising: control means for controlling at least the intake air amount adjusting valve and the exhaust gas recirculation valve based on the detected operating state;
The control means turns the exhaust gas recirculation valve to a fully closed state when the exhaust gas recirculation valve is opened and the engine is decelerating from a state where the intake air is boosted by the supercharger. In order to compensate for the intake amount deficient due to the inflow of the exhaust gas recirculation gas into the intake passage in the process of closing the intake air amount adjusting valve and closing the intake air amount adjusting valve. The closing speed of the intake air amount adjusting valve is set so that the intake air amount adjusting valve is at a time when the engine is decelerating from the state where the exhaust gas recirculation valve is closed and the intake air is boosted by the supercharger. For the valve closing speed when the valve closing control is performed,
The engine includes a fresh air introduction passage for introducing fresh air into the intake passage downstream from the intake air amount adjustment valve, and a fresh air introduction valve for adjusting the amount of fresh air flowing through the fresh air introduction passage. In addition,
The control means opens the fresh air introduction valve when the exhaust gas recirculation valve is opened and the engine is decelerating from a state where the intake air is boosted by the supercharger,
The fresh air introduction passage is provided with a check valve for restricting the backflow of gas from the intake passage, and controls the intake air amount adjustment valve to a final opening degree close to full closure during the deceleration operation of the engine. An engine control device that corrects the final opening so that the final opening decreases as the opening of the fresh air introduction valve increases. The control means in claim 2, characterized in that to correct the said final opening to final opening becomes smaller the higher the load of the engine detected increases as the driving state the intake flow control valve The engine control device described. The said control means correct | amends the said final opening so that the said final opening of the said intake amount adjustment valve may become small, so that the intake pressure in the said intake passage detected as the said operation state becomes high. the engine control apparatus according to 2.

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