JP6421796B2 - Engine control device - Google Patents

Description

  The present invention relates to an engine control device that includes an intake passage that allows intake air to flow into an engine body and a throttle valve that opens and closes the intake passage.

  Conventionally, in an engine in which a throttle valve is provided in an intake passage, various measures have been taken to prevent the throttle valve from sticking. In other words, combustion gas may be introduced into the intake passage, and soot contained in the combustion gas may accumulate on a portion around the throttle valve in the intake passage and the throttle valve may be fixed, and this should be avoided. Is being considered.

  For example, in Patent Document 1, the throttle valve is forcibly fully closed when the engine is stopped or the fuel cut operation is performed, and the throttle valve collides with the soot accumulated around the throttle valve in the intake passage to remove the soot. An engine designed to do so is disclosed. In this engine, when the engine is stopped, the throttle valve is suddenly closed from the opening during normal operation to the fully closed position, and soot is removed in a relatively short period after the engine is stopped. Can do.

JP 2001-173464 A

  However, if the throttle valve is suddenly closed to the fully closed position as in Patent Document 1 during the fuel cut operation, the amount of gas flowing into the engine main body is drastically reduced. As a result, the pumping loss increases rapidly, and the deceleration of the engine body increases rapidly. Therefore, when this engine is mounted on a vehicle, the ride comfort may not be sufficiently good. On the other hand, for example, it is conceivable that the control to fully close the throttle valve is performed only when the engine is stopped. Etc. cannot be removed properly, and the throttle valve cannot be sufficiently prevented from sticking.

  The present invention has been made in view of the circumstances as described above, and an object of the present invention is to provide an engine control device capable of suppressing sticking of a throttle valve while suppressing a sudden change in deceleration of an engine body. To do.

In order to solve the above problems, the present invention is an apparatus for controlling an engine mounted on a vehicle, comprising an intake passage for allowing intake air to flow into an engine body and a throttle valve for opening and closing the intake passage. determining the detectable intake pressure detecting means intake pressure is the pressure of the portion of the downstream side of the throttle valve of the passage, whether or not the fuel supply to the engine main body is a fuel cut operation is stopped as well as, a determination means based whether there is a request to carry out sticking avoidance control that makes closing the throttle valve to the fully closed to the travel distance of the vehicle, based on the determination result by the determination means, the fixed or performing the avoidance control or a throttle control means for performing a normal control for setting the opening degree of the throttle valve opening side of the opening than the fully closed For example, the throttle control means is either determined that there is no execution request for the fixation avoiding control, or when even if the execution request is determined not to be a fuel cut operation by the determination unit, the normal control When the determination means determines that the sticking avoidance control is to be performed and the fuel cut operation is being performed, the sticking avoidance control is performed, and the throttle control means during the implementation of the control from the start of closing of the throttle valve, setting the intake pressure opening is detected by且one above Symbol intake pressure detecting means becomes less than the reference opening degree is set in advance of the throttle valve is previously The throttle valve is closed at the first valve closing speed until the specified time when the pressure becomes less than the reference pressure, and after the specified time, the throttle valve is closed. The provides a control apparatus for an engine, characterized in that to close the closed or full at the second closing speed lower than the first closing speed (claim 1).

  According to the present invention, the sticking avoidance control for fully closing the throttle valve during the fuel cut operation of the engine is performed. Therefore, unlike the case where the throttle valve is fully closed only when the engine is stopped, there are many opportunities for the throttle valve to be fully closed, and the trap between the intake passage and the throttle valve is properly secured. It is possible to suppress the sticking of the throttle valve.

  In addition, according to the present invention, when the sticking avoidance control is performed, after the specific time when the throttle valve opening is less than the reference opening and the intake air pressure is less than the reference pressure, the throttle valve is closed at the closing speed ( The valve is closed at a second valve closing speed smaller than the first valve closing speed). Therefore, it is possible to suppress a rapid increase in the deceleration of the engine body while fully closing the throttle valve. Therefore, it is possible to suppress sticking of the throttle valve while suppressing a sudden increase in the deceleration of the engine body and improving the riding comfort when the engine is mounted on the vehicle.

Specifically, when the throttle valve opening is small, the sensitivity of the intake pressure relative to this opening (the change in intake pressure relative to the change in the throttle valve opening) is high. The deceleration of is likely to increase rapidly. On the other hand, in the present invention, when the opening degree of the throttle valve falls below the reference opening degree, the closing speed of the throttle valve is reduced. Therefore, the rate of change of the intake pressure accompanying the closing of the throttle valve can be kept small, and the rapid increase in the deceleration of the engine body can be suppressed. Furthermore, when the throttle valve is fully closed while the intake pressure is high, the amount of intake pressure drop increases and the deceleration of the engine body increases. On the other hand, in the present invention, the throttle valve is fully closed after the intake pressure has dropped below the reference pressure . For this reason, it is possible to suppress a drop in intake pressure caused by fully closing the throttle valve, and to suppress a rapid increase in the deceleration of the engine body.

In the present invention, as the first valve closing speed, an initial first valve closing speed and a late first valve closing speed smaller than the initial first valve closing speed and larger than the second valve closing speed are set. The throttle control means starts the closing of the throttle valve during the execution of the sticking avoidance control, and then has an intermediate setting in which the opening of the throttle valve is preset as an opening higher than the reference opening Until the opening is reached, the throttle valve is closed at the initial first closing speed, and the throttle valve is closed until the specific time after the opening of the throttle valve reaches the intermediate setting opening. It is preferable that the valve is closed at the late first valve closing speed, and is closed until the valve is fully closed at the second valve closing speed after the specified time .

  In this configuration, the throttle valve is closed at a higher initial first valve closing speed while the throttle valve opening is relatively larger than the intermediate setting opening and the sensitivity of the intake pressure to the throttle valve opening is small. . Therefore, the throttle valve can be fully closed earlier while suppressing an excessive change in the intake pressure, that is, an excessive increase in the deceleration of the engine body.

  Further, in the present invention, the throttle control means opens the throttle valve when the fuel supply to the engine body is resumed after the throttle valve is fully closed as the sticking avoidance control is performed. Is preferably gradually increased toward the target opening degree set to the opening side rather than the fully closed state (Claim 3).

  In this way, sudden changes in the intake pressure can be suppressed even when the throttle valve is returned from the fully closed state to the opening during normal operation as the fuel supply resumes, and the behavior of the engine body is stabilized. The riding comfort of a vehicle equipped with this engine can be improved.

  In the above configuration, when the throttle valve opening is gradually increased from fully closed as the fuel supply is resumed, the throttle control means determines the throttle valve opening as an absolute value of the first valve closing speed. It is preferable to increase at a rate larger than the absolute value of (Claim 4).

  In this way, the intake pressure can be increased quickly without excessively increasing when the fuel supply is resumed.

In the present invention, the throttle control means controls the opening degree of the throttle valve to be fully closed even when the engine body is stopped, and the determination means is a vehicle after the opening degree of the throttle valve is fully closed. preferably determined to come and travel distance reaches a preset reference distance or more is execution request of the sticking prevention control (claim 5).

  If it does in this way, it can control that the opportunity which makes a throttle valve fully closed during operation of an engine becomes excessive, suppressing sticking of a throttle valve appropriately.

Further, in the present invention, the throttle control means has a gear stage less than a preset reference gear stage even when the execution of the sticking avoidance control is requested and it is determined that the fuel cut operation is being performed. preferably, to prohibit the implementation of the above SL sticking avoidance control in the case (claim 6).

  According to this configuration, it is possible to suppress the deterioration of the riding comfort due to the sticking avoidance control when the gear stage is low and the amount of change in the vehicle speed due to the change in the deceleration of the engine body is likely to be large.

Further, in the present invention, an EGR passage that recirculates part of the exhaust discharged from the engine body to the intake passage, an EGR valve that opens and closes the EGR passage, and when the EGR valve is opened, the EGR valve is opened. preferably provided with an EGR control means for controlling the degree to side opening than during normal operation (claim 7).

  In this way, it is possible to reduce the pumping loss by increasing the intake pressure and reducing the exhaust pressure at the time of the sticking avoidance control, and it is possible to prevent the deceleration of the engine body from becoming excessively large.

  As described above, according to the engine control apparatus of the present invention, it is possible to suppress sticking of the throttle valve while suppressing a sudden change in the deceleration of the engine body.

It is a figure showing composition of an engine system concerning one embodiment of the present invention. It is the schematic sectional drawing which expanded and showed the circumference of a throttle valve. It is the block diagram which showed the control system of the engine system shown in FIG. It is the flowchart which showed the basic control procedure of the EGR valve. It is the figure which showed the map of the EGR path | route at the time of complete warming-up. It is the figure which showed the map of the EGR path | route before warming up. It is the flowchart which showed the basic control procedure of the throttle valve. It is a figure for demonstrating the deposition state of a soot, and the procedure at the time of removing this. It is the flowchart which showed the determination procedure whether to implement sticking avoidance control. It is the flowchart which showed the procedure of sticking avoidance control. It is the flowchart which showed the control procedure at the time of fuel return. It is the figure which showed the time change of each parameter at the time of sticking avoidance control implementation.

(1) Overall Configuration of Engine FIG. 1 is a diagram showing an overall configuration of an engine system including an engine control device according to an embodiment of the present invention. The engine shown in the figure is a four-cycle diesel engine mounted on a vehicle as a power source for traveling. The specific type of engine is not limited to this, and may be, for example, a gasoline engine.

  The engine system includes an engine main body 1, an intake passage 30 for introducing combustion air into the engine main body 1, an exhaust passage 40 for discharging exhaust generated by the engine main body 1 to the outside of the vehicle, and an exhaust passage. EGR device 50 for returning a part of the exhaust gas passing through 40 to intake passage 30, and first turbocharger 60 and second turbocharger 70 driven by the exhaust gas passing through exhaust passage 40 Prepare.

  The engine body 1 includes a cylinder block 3 in which a cylinder 2 is formed, a cylinder head 5 provided on the upper surface of the cylinder block 3, and a piston 4 inserted into the cylinder 2 so as to be slidable back and forth. Yes. A combustion chamber 9 is formed above the piston 4.

  The cylinder head 5 is provided with one set of injectors 20 for each cylinder 2. The injector 20 is attached in such a posture that the tip on the piston 4 side faces the center of the combustion chamber 9.

  The injector 20 injects fuel into the combustion chamber 9. The injected fuel / air mixture burns in the combustion chamber 9, and the piston 4 is pushed down by the expansion force caused by the combustion and reciprocates up and down.

  The piston 4 is connected to the crankshaft 7 via a connecting rod, and the crankshaft 7 rotates about its central axis in accordance with the reciprocating motion of the piston 4.

  The cylinder head 5 includes an intake port 16 for introducing air supplied from the intake passage 30 into the combustion chamber 9 of each cylinder 2, an intake valve 18 that opens and closes the intake port 16, and the combustion chamber 9 of each cylinder 2. Are provided with an exhaust port 17 for leading the exhaust gas generated in step 1 to the exhaust passage 40 and an exhaust valve 19 for opening and closing the exhaust port 17.

  In the intake passage 30, an air cleaner 31, a compressor 61 of the first turbocharger 60, a compressor 71 of the second turbocharger 70, an intercooler 35, a throttle valve 36a, and a surge tank 37 are provided in this order from the upstream side. ing. On the downstream side of the surge tank 37, there are provided independent passages individually communicating with the cylinders 2. The cylinders 2 are filtered by the air cleaner 31 and compressed by the compressors 61 and 62, respectively. The air cooled by the cooler 35 is distributed through the surge tank 37 and these independent passages.

  The intake passage 30 is provided with a compressor bypass passage 33 that bypasses the compressor 71 of the second turbocharger 70, and a valve 33a that opens and closes the passage 33, and the valve 33a is opened. The air flows into the intercooler 35 without being compressed by the compressor 71 of the second turbocharger 70.

  The throttle valve 36a opens and closes the intake passage 30. The throttle valve 36a is provided in the intake passage 30 upstream of a connection portion of an EGR passage 51 described later.

  The throttle valve 36 a is a butterfly valve and rotates about an axis extending in a direction orthogonal to the flow path of the intake passage 30 to open and close the intake passage 30. The intake passage 30 is provided with a valve actuator 36b for driving the throttle valve 36a, and the throttle valve 36a is rotationally driven by the valve actuator 36b. The valve actuator 36b is, for example, an electric type, and changes the opening degree of the throttle valve 36a by changing the DUTY ratio of the supplied current.

  FIG. 2 is an enlarged schematic cross-sectional view showing the periphery of the throttle valve. As shown in FIG. 2, specifically, the throttle valve 36 a is in a fully closed position indicated by a chain line in FIG. 2, that is, a position that closes almost the entire flow path formed inside the intake passage 30. It is rotationally driven between the fully open position shown by the solid line in FIG. 2, and the opening degree of the throttle valve 36a is continuously changed between the fully closed position and the fully open position. In the present embodiment, the throttle valve 36a is a fully opened position that is rotated 82 degrees in the direction indicated by the arrow Y1 in FIG. 3 from the fully closed position, and the fully closed position is 0 degree to 0 degrees to 82 degrees. The opening can be changed between.

  In the exhaust passage 40, in order from the upstream side, the turbine 62 of the first turbocharger 60, the turbine 72 of the second turbocharger 70, and a plurality of purification devices 81 for purifying harmful components in the exhaust. -85.

  In each turbocharger 60, 70, the turbines 62, 72 are rotated by receiving the energy of the exhaust gas flowing through the exhaust passage 40, and the compressors 61, 71 connected to the turbines 62, 72 are linked to this. By rotating, the air flowing through the intake passage 30 is compressed (supercharged).

  The exhaust passage 40 bypasses the first turbine bypass passage 41 that bypasses the turbine 62 of the first turbocharger 60, the valve 41 a that opens and closes the passage 41, and the turbine 72 of the second turbocharger 70. A second turbine bypass passage 42 and a valve 42a for opening and closing the passage 42 are provided. The bypass passages 41 and 42 are opened and closed by the valves 41a and 42a, so that exhaust passes through the turbines 62 and 72. Whether to pass or bypass each turbine 62, 72 is changed.

  For example, when both valves 41a and 42a are opened, most of the exhaust gas does not pass through any of the turbines 62 and 72 and flows into the purification device 81, and the intake air is introduced into the engine body 1 without being supercharged. .

  In this embodiment, an NSC (NOx Storage Catalyst) device 81, a DOC device 82, and a DPF (Disel Particulate Filter, filter) 83 are provided in order from the upstream side as a purification device, and an SCR (Selective Catalytic) is further downstream of the DPF 83. A reduction device 84 and a slip catalyst device 85 are provided.

  The NSC device 81 is a catalyst device in which a NOx occlusion reduction catalyst 81a is built, and stores NOx in the exhaust to suppress discharge to the outside.

Further, the NSC device 81 reduces the stored NOx to be harmless N ₂ by supplying the reducing agent. Specifically, the ECU 100 described later estimates the amount of NOx occluded in the NSC device 81. When the estimated amount becomes equal to or larger than a predetermined amount, the ECU 100 exhausts the air excess ratio λ of the air-fuel mixture in the cylinder 2 to be rich (less than 1) in order to reduce the NOx stored in the NSC device 81. DeNOx control is performed in which unburned fuel is contained in the NSC device 81 and the unburned fuel is supplied to the NSC device 81 as a reducing agent. By this DeNOx control, unburned fuel is supplied to the NSC device 81 as a reducing agent, and thereby NOx stored in the NSC device 81 is reduced.

  The DOC device 82 is a catalyst device in which an oxidation catalyst 82a is built.

  The DPF 83 is a filter that can collect particulate matter such as soot in the exhaust, and collects soot and the like in the exhaust to suppress discharge to the outside.

  The soot collected in the DPF 83 is appropriately removed by performing the DPF regeneration control. Specifically, the ECU 100 estimates the amount of soot collected in the DPF 83. When the estimated amount of soot becomes equal to or greater than a predetermined amount, the ECU 100 makes the excess air ratio λ of the air-fuel mixture in the cylinder 2 rich (less than 1) in order to burn and remove the soot, so that the exhaust is unburned. Regeneration control is performed in which fuel is contained and this unburned fuel is burned in the DPF 83.

  The SCR device 84 is a catalyst device with a built-in catalyst 84a that receives the supply of ammonia generated by the decomposition of urea and reduces NOx. In the present embodiment, a urea injector 49 for adding urea is provided in a portion of the exhaust passage 40 between the DPF 83 and the SCR device 84, and urea is supplied from the urea injector 49 toward the SCR device 84. .

  The slip catalyst device 85 is a catalyst device in which an oxidation catalyst 85a is built. The slip catalyst device 85 mainly oxidizes the ammonia discharged from the SCR device 84 to make it harmless.

  The EGR device 50 is for returning a part of the exhaust gas to the intake side. The EGR device 50 includes an EGR passage 51 that connects a portion of the exhaust passage 40 upstream of the second turbine 62 and a portion of the intake passage 30 downstream of the intercooler 35, and this EGR passage A part of the exhaust gas (less than, sometimes referred to as EGR gas) is recirculated to the intake side via 51.

  In the present embodiment, as shown in FIG. 2, an opening hole is formed in the outer surface of the tip portion on the downstream side of the EGR passage 51, and the tip portion in which this opening hole is formed is inserted inside the intake passage 30. Has been. The EGR gas flows from the EGR passage 51 into the intake passage 30 through the opening hole.

  The EGR passage 51 branches into a first EGR passage 51a and a second EGR passage 51b along the way. The first EGR passage 51 a is provided with an EGR cooler 55, and the gas passing through the first EGR passage 51 a is cooled by the EGR cooler 55. The first EGR passage 51a and the second EGR passage 51b are provided with a first EGR valve 52a and a second EGR valve 52b that open and close the passages 51a and 51b, respectively, and the recirculation amount of EGR gas by opening and closing these EGR valves 52a and 52b. And the EGR gas path, that is, whether the EGR gas is recirculated through both the first EGR passage 51a and the second EGR passage 51b or through which passage the EGR gas is recirculated is changed. Hereinafter, this EGR gas path is referred to as an EGR path, the path through which the EGR gas is recirculated through the first EGR passage 51a is referred to as a first path, and the path through which the EGR gas is recirculated through the second EGR path 51b is referred to as a second path.

(2) Control System Next, the control system of the engine system will be described with reference to FIG. Engine system of this embodiment is controlled by an ECU (engine control unit) 100 provided in the vehicle. As is well known, the ECU 100 is a microprocessor including a CPU, ROM, RAM, I / F, and the like. The ECU 100 corresponds to determination means, throttle control means, and EGR control means in the present invention.

  Information from various sensors is input to the ECU 100. For example, the ECU 100 includes an engine speed sensor SE1, an air flow sensor SE2, an intake pressure sensor (intake pressure detection means) SE3, a throttle opening sensor SE4, a first EGR opening sensor SE5, an exhaust oxygen concentration sensor SE6, an engine water temperature sensor SE7, It is electrically connected to an accelerator opening sensor SE8, a vehicle speed sensor SE9, and the like, and receives input signals from these sensors SE1 to SE9.

  The engine speed sensor SE <b> 1 is a sensor that detects the speed of the crankshaft 7 as the speed of the engine body, that is, the engine speed, and is attached to the cylinder block 3. The air flow sensor SE <b> 2 is a sensor that detects the flow rate of intake air passing through the intake passage 30, and is attached between the air cleaner 31 and the compressor 61 of the first turbocharger 60 in the intake passage 30. The intake pressure sensor SE3 is a sensor that detects the pressure on the downstream side of the throttle valve 36a in the intake passage 30 as the intake pressure, and is attached to the surge tank 37. That is, in the present embodiment, the pressure in the portion of the intake passage 30 between the connection portion of the EGR passage 51 and the engine body 1 is detected as the intake pressure. The throttle opening sensor SE4 and the first EGR opening sensor SE5 are sensors that detect the opening of the throttle valve 36a and the opening of the first EGR valve 52a, respectively. The exhaust oxygen concentration sensor SE6 is a sensor that detects the oxygen concentration of the exhaust gas flowing through the exhaust passage 40. The engine water temperature sensor SE <b> 7 is a sensor that detects the temperature of engine cooling water for cooling the engine body 1. The accelerator opening sensor SE8 and the vehicle speed sensor SE9 are sensors that detect the opening of the accelerator pedal (not shown) and the vehicle speed, respectively.

  The ECU 100 controls each part such as the injector 20, the throttle valve 36a, the first EGR valve 52a, and the second EGR valve 52b while performing various calculations based on input signals from various sensors such as SE1 to SE9.

(2-1) Basic Control Basic control of the injector 20, the throttle valve 36a, the first EGR valve 52a, and the second EGR valve 52b by the ECU 100 will be described next.

(Injector)
First, basic control of the injector 20 will be described.

  The ECU 100 calculates the injection pattern of the injector 20 and the injection amount of the injector 20 (the amount of fuel injected from the injector 20) based on the accelerator opening, the vehicle speed, the gear stage, and the like. That is, in this embodiment, the injector 20 is capable of multi-stage injection, and is configured such that its injection pattern changes according to operating conditions. In the present embodiment, the current gear stage is calculated by the ECU 100 based on the vehicle speed and the engine speed.

  Specifically, the ECU 100 calculates the acceleration of the vehicle requested by the driver based on the accelerator opening and the like, and calculates the target engine torque that is the target value of the engine torque, that is, the engine load based on this. . Next, ECU 100 determines an injection pattern based on the engine speed and the engine load. Specifically, a map of injection patterns for engine speed and engine load is stored in advance in ECU 100, and ECU 100 extracts an injection pattern corresponding to the current engine speed and engine load from this map. Next, the ECU 100 determines an injection amount based on the determined injection pattern and engine load. Specifically, the combustion efficiency is obtained in advance for each injection pattern and stored in the ECU 100, and the ECU 100 determines the injection amount based on the combustion efficiency corresponding to the determined injection pattern and the engine load.

(EGR valve)
Next, basic control of the first EGR valve 52a and the second EGR valve 52b will be described using the flowchart of FIG.

  First, ECU 100 reads the engine speed, engine load, and the like in step S1.

  Next, the ECU 100 estimates the in-cylinder oxygen concentration that is the concentration of oxygen in the cylinder 2 in step S2. For example, the ECU 100 estimates the in-cylinder oxygen concentration based on the intake air amount, the exhaust oxygen concentration, and the like.

  Next, in step S3, the ECU 100 sets a target value of the intake oxygen concentration that is the oxygen concentration of the air-fuel mixture in the cylinder 2 (air-fuel mixture before combustion) based on the engine speed, the engine load, and the like. For example, the ECU 100 stores in advance an intake oxygen concentration that can appropriately suppress the generation of NOx and soot with respect to the engine speed and the engine load, and from this map, the current engine speed and the engine load are stored. Extract values corresponding to.

  Next, in step S4, the ECU 100 determines an EGR path based on the engine speed, the engine load, and the engine water temperature.

  In the present embodiment, the maps of FIGS. 5 and 6 are stored in advance in the ECU 100. These maps in FIGS. 5 and 6 are maps in which the EGR path is determined for the engine speed and the engine load. The map in FIG. 5 is a map in a state where the engine body 1 is completely warmed up, and the map in FIG. Is a map in a state before the engine body 1 is completely warmed up.

  As shown in FIG. 5, in the present embodiment, when the engine body 1 is in a completely warm-up state, the EGR route is only the second route in the operation region A1 where the engine speed and the engine load are extremely low. Further, in the operation region A2 where the engine speed and engine load are higher than this, the EGR route is both the first route and the second route, and in the operation region A3 where the engine load and engine speed are higher than this. The EGR route is only the first route. In the operation region A4 where the engine speed and the engine load are high, the recirculation of EGR gas is stopped.

  On the other hand, as shown in FIG. 6, when the engine body 1 is not completely warmed up, the recirculation of EGR gas is stopped in the operation region B2 where the engine speed and the engine load are high. In the operation region B1 other than the operation region B2, the EGR route is only the second route.

  The ECU 100 first determines which of the map of FIG. 5 and the map of FIG. 6 is to be adopted according to the engine water temperature. Specifically, the ECU 100 adopts the map of FIG. 5 when the engine water temperature is equal to or higher than a preset temperature and the engine body 1 is completely warmed up, and adopts the map of FIG. 6 in other cases. To do. Next, the ECU 100 determines an EGR path corresponding to the current engine speed and engine load based on the adopted map.

  Next, in step S5, the ECU 100 determines the target EGR valve that is the target value of the opening degree of the EGR valve based on the target intake oxygen concentration set in step S3 and the estimated value of the in-cylinder oxygen concentration calculated in step S2. Set the opening.

  At this time, the target value of the opening degree of the EGR valve corresponding to the route not adopted as the EGR route in step S4 is set to 0 (fully closed). Then, ECU 100 sets the target value of the opening degree of the EGR valve corresponding to the route adopted as the EGR route based on the target intake oxygen concentration and the estimated value of the in-cylinder oxygen concentration. In the present embodiment, the ECU 100 is based on the deviation between the estimated value of the in-cylinder oxygen concentration and the target intake oxygen concentration, the exhaust oxygen concentration, and the like so that the estimated value of the in-cylinder oxygen concentration becomes the target intake oxygen concentration. Set the target EGR valve opening.

  Thereafter, in step S6, the ECU 100 controls the opening degree of the EGR valve to the target EGR valve opening degree set in step S5. Specifically, a drive signal is transmitted to the actuator that drives the EGR valve so that the opening degree of the EGR valve becomes the target EGR valve opening degree.

(Throttle valve)
Next, basic control of the throttle valve 36a will be described using the flowchart of FIG.

  First, ECU 100 determines in step S11 whether engine body 1 is stopped.

  If the determination in step S11 is YES and the engine body 1 is stopped, the ECU 100 proceeds to step S12, and the opening of the throttle valve 36a is fully closed (0 degree), and the process is terminated. Thus, in this embodiment, when the engine body 1 stops, the throttle valve 36a is fully closed.

  On the other hand, if the determination in step S11 is NO and the engine main body 1 is operating, the ECU 100 proceeds to step S13 and reads the operating state such as the engine speed.

  Next, in step S14, the ECU 100 determines whether to perform intake throttle control based on the read operating state.

  The intake throttle control is a control for setting the opening of the throttle valve 36a to a relatively small (closed) opening in order to reduce the amount of intake air flowing into the engine body 1, and when the determination in step S12 is YES, The ECU 100 proceeds to step S15, sets the opening of the throttle valve 36a to the minimum opening, and ends the process.

  The above-mentioned minimum opening is an opening larger than the fully closed (0 degree), and is an opening at which the throttle valve 36a is controlled while the engine body 1 is in operation (except when the sticking avoidance control described later is performed). Is the smallest opening. This minimum opening is set to about 5 degrees, for example.

  The intake throttle control is performed during idle operation, when DPF regeneration control is performed, and when DeNOx control is performed.

  Specifically, during idle operation, the EGR gas is difficult to recirculate because the pressure of the exhaust gas decreases due to the small supercharging capability of the turbochargers 60 and 70. Therefore, in the present embodiment, intake throttle control is performed during idle operation, thereby reducing the intake pressure and promoting the recirculation of EGR gas.

  Further, in the DPF regeneration control, the excess air ratio λ of the air-fuel mixture in the cylinder needs to be rich (less than 1) as described above, and the temperature in the DPF 83 is increased so that soot is burned and removed in the DPF 83. It is necessary to keep the exhaust temperature high. Therefore, in the present embodiment, the intake throttle control is performed during the DPF regeneration control, and the amount of fresh air flowing into the cylinder 2 is suppressed to be small.

  Similarly, it is necessary to enrich the excess air ratio λ of the air-fuel mixture in the cylinder 2 and to increase the temperature in the NSC device 81 and thus the temperature of the exhaust gas even during DeNOx control. Therefore, in the present embodiment, the intake throttle control is also performed during the DeNOx control, and the amount of fresh air flowing into the cylinder 2 is suppressed to be small.

  On the other hand, if the determination in step S14 is NO, that is, if it is not during idle operation, DPF regeneration control execution, or DeNOx control execution, the ECU 100 proceeds to step S16 and proceeds to step S16. The process is terminated with the opening of 36a being fully open (excluding sticking avoidance control described later).

  As described above, in the present embodiment, the throttle valve 36a is fully opened during normal operation except when the intake throttle control and the sticking avoidance control are performed while the engine is operating. In particular, in the present embodiment, except when the intake throttle control and the sticking avoidance control are performed, when the engine is running, the fuel is supplied into the cylinder 2 and the supply of fuel into the cylinder 2 is stopped. The throttle valve 36a is fully opened in both cases of the fuel cut operation.

(2-2) Sticking Avoidance Control The sticking avoidance control performed by the ECU 100 will be described.

  The sticking avoidance control is control for avoiding that the throttle valve 36a is stuck and cannot be operated properly. That is, as shown in FIG. 8, with the operation of the engine, soot C contained in the combustion gas accumulates around the portion of the inner peripheral surface of the intake passage 30 where the throttle valve 36a is provided. In particular, when the EGR passage 51 is connected to the intake passage 30 as in the present embodiment, EGR gas is introduced from the EGR passage 51 into the intake passage 30 as indicated by an arrow Y2 in FIG. The soot C contained in the EGR gas is likely to be deposited around the throttle valve 36a. When the accumulated soot C cools and hardens when the engine is stopped, the throttle valve 36a is fixed, or proper operation of the throttle valve 36a is hindered.

  Here, as described above, in the present embodiment, the throttle valve 36a is fully closed when the engine is stopped. Therefore, when the engine is stopped, the throttle valve 36a can collide with the accumulated soot C to remove the soot C as shown by the chain line from the state shown by the solid line in FIG. However, when there are few opportunities for the engine to stop, the accumulated soot C may not be sufficiently removed only by fully closing the throttle valve 36a when the engine is stopped. Therefore, in the present embodiment, the sticking avoidance control for closing the throttle valve 36a toward the fully closed state is performed when a predetermined condition is satisfied even when the engine body 1 is in operation.

  First, a determination procedure for determining whether or not to perform the sticking avoidance control performed by the ECU 100 will be described with reference to the flowchart of FIG.

  In step S21, the ECU 100 reads the operating state such as the engine speed.

  Next, ECU 100 determines in step S22 whether or not there is a request for execution of the sticking avoidance control. That is, the ECU 100 determines whether or not soot C has accumulated in the vicinity of the throttle valve 36a and needs to be removed.

  The accumulation amount of 煤 C is substantially proportional to the travel distance of the vehicle. Therefore, in the present embodiment, in step S22, the ECU 100 determines that the travel distance of the vehicle has been previously set after the throttle valve 36a has been fully closed (after the engine has been stopped or the previous sticking avoidance control has been performed). It is determined whether or not the set reference distance has been exceeded, and if this determination is YES, it is assumed that there is a request for execution of sticking avoidance control by estimating that a predetermined amount or more of soot C has accumulated around the throttle valve 36a. . The reference distance may be appropriately set according to the engine body displacement or the like, and is set to 40 km, for example.

  If the determination in step S22 is NO and there is no request for execution of sticking avoidance control, the ECU 100 proceeds to step S29 and performs normal control that is not sticking avoidance control. That is, the ECU 100 proceeds to step S11 in the flowchart of FIG.

  On the other hand, if the determination in step S22 is YES and there is a request to perform the sticking avoidance control, the ECU 100 proceeds to step S23.

  In step S23, the ECU 100 determines whether or not the fuel cut operation is being performed (during deceleration F / C), that is, whether the supply of fuel from the injector 20 into the cylinder 2 is stopped while the engine body 1 is operating. Determine whether or not.

  If the determination in step S23 is NO and the fuel cut operation is not being performed, the ECU 100 proceeds to step S29.

  On the other hand, when the determination in step S23 is YES and the fuel cut operation is being performed, the ECU 100 proceeds to step S24.

  In step S24, the ECU 100 determines whether or not the gear stage is a high speed stage that is equal to or higher than a preset reference gear stage. The reference gear stage is set to a predetermined value of 2nd speed or higher, for example, 4th speed. In the present embodiment, the ECU 100 calculates the current gear stage based on the vehicle speed and the engine speed, and determines whether this gear stage is equal to or higher than the reference gear stage.

  If the determination in step S24 is no and the gear stage is less than the reference gear stage, the ECU 100 proceeds to step S29.

  On the other hand, if the determination in step S24 is YES and the gear stage is a high speed stage greater than or equal to the reference gear stage, the ECU 100 proceeds to step S25.

  In step S25, the ECU 100 determines whether or not the intake pressure is less than a preset reference start pressure P1. The reference start pressure P1 is a value equal to or higher than the atmospheric pressure, and is set to about 140 kPa, for example.

  If the determination in step S25 is no and the intake pressure is greater than or equal to the reference start pressure P1, the ECU 100 proceeds to step S29.

  On the other hand, if the determination in step S25 is YES and the intake pressure is less than the reference start pressure P1, the ECU 100 proceeds to step S26 and determines to perform the sticking avoidance control.

  As described above, in the present embodiment, the fuel cut is performed when the vehicle travel distance after the throttle valve 36a is fully closed last time is equal to or greater than the reference distance, and the gear stage is the reference gear stage. The sticking avoidance control is performed only when the intake pressure is lower than the reference start pressure P1. The control according to the flowchart of FIG. 9 is also executed during the execution of the sticking avoidance control. If any one of steps S23 to S25 is NO during the execution of the sticking avoidance control, the sticking avoidance control is performed. Is stopped and returned to normal control.

  Next, the procedure of sticking avoidance control will be described using the flowchart of FIG.

  When all the determinations in steps S22 to S25 are YES and execution of the sticking avoidance control is determined in step S26, the ECU 100 increases the opening degree of the first EGR valve 52a in step S31, thereby increasing the first EGR valve. 52a is controlled to open more than the opening during normal control (opening realized when sticking avoidance control is not performed). At this time, the opening degree of the first EGR valve 52a is set such that the opening speed (the increase amount of the actual opening degree of the first EGR valve 52a per unit time) becomes a preset reference EGR valve opening speed β1. Increase gradually. In addition, the first EGR valve 52a is opened toward full open.

  In the present embodiment, during the normal fuel cut operation except when the sticking avoidance control is performed, the EGR valves 52a and 52a are controlled to be fully closed with the start of the fuel cut. Therefore, in step S31, the second EGR valve 52a is fully closed, while the first EGR valve 52a is opened, and the EGR path is only the first EGR path.

  If it is determined that the sticking avoidance control is to be executed after a short time after the fuel cut (eg, if the determination in step S24 or step S25 is YES after a short time after the fuel cut), the first EGR valve 52a may Once fully closed, the valve is gradually opened from the fully closed state. Further, when the fuel cut is performed with the first EGR valve 52a fully opened, and when the sticking avoidance control is performed simultaneously with the fuel cut, the opening degree of the first EGR valve 52a is maintained fully opened.

  Next, in step S32, the ECU 100 determines whether or not the opening degree of the first EGR valve 52a is equal to or greater than a preset reference EGR opening degree E1. The reference EGR opening degree E1 is set to an opening degree that is smaller than the full opening.

  If the determination in step S32 is yes, the ECU 100 proceeds to step S33. On the other hand, if the determination in step S32 is NO and the opening degree of the first EGR valve 52a has not reached the reference EGR opening degree E1, the ECU 100 returns to step S31.

  As described above, in the present embodiment, the closing of the throttle valve 36a is not started immediately after the execution of the sticking avoidance control is decided, but first, gradually until the first EGR valve 52a reaches the reference EGR opening degree E1. The valve is opened. Note that the first EGR valve 52a is opened toward the fully open state even after the reference EGR opening degree E1 is reached. Then, after being fully opened, it is kept fully open until the sticking avoidance control is stopped.

  In step S33, the ECU 100 sets a target throttle opening, which is a target value of the opening of the throttle valve 36a, to a preset first throttle opening (intermediate set opening) ETB1. The first throttle opening ETB1 is an opening larger than the minimum opening and smaller than the full opening, and is the smallest opening in a so-called dead zone where the intake pressure does not substantially change even when the opening of the throttle valve 36a is changed. Is set to degrees. That is, in the present embodiment, the intake pressure changes with the change in the opening of the throttle valve 36a only when the opening of the throttle valve 36a is less than the predetermined opening, and the first throttle opening ETB1. Is set to this predetermined opening. For example, in the throttle valve 36a that is fully opened at 82 degrees as described above, the first throttle opening ETB1 is set to about 50 degrees.

  Next, in step S34, the ECU 100 changes the opening of the throttle valve 36a so that the first throttle opening ETB1 is obtained. As described above, the opening degree of the throttle valve 36a is set to be fully open during normal control, and until the step S34 (at least from the start of the fuel cut to the step S34), the throttle valve 36a is opened. Is fully open, and in step S34, the throttle valve 36a is closed from the fully open position toward the first throttle opening ETB1.

  Next, in step S35, the ECU 100 determines whether or not the opening of the throttle valve 36a is less than the first throttle opening ETB1.

  If the determination in step S35 is YES, ECU 100 proceeds to step S36. On the other hand, if the determination in step 35 is NO, the ECU 100 returns to step S34 and further closes the throttle valve 36a. In this way, the ECU 100 first closes the throttle valve 36a toward the first throttle opening ETB1.

  In step S36, the ECU 100 causes the throttle valve 36a to be closed at a preset late first valve closing speed α1_B. That is, the ECU 100 sets the throttle valve 36a to the first throttle opening ETB1 so that the closing speed of the throttle valve 36a (the amount of decrease in the opening of the throttle valve 36a per unit time) becomes the late first valve closing speed α1_B. We will close the valve further. Specifically, the ECU 100 gradually decreases the target throttle opening at the late first valve closing speed α1_B, and thereby reduces the opening of the throttle valve 36a at the late first valve closing speed α1_B.

  Here, in step S34, the target throttle opening is changed stepwise from fully open to first throttle opening ETB1 in step S33, and the throttle valve 36a is closed accordingly. Therefore, the valve closing speed of the throttle valve 36a from step S33 to step S35 is a value larger than the latter first valve closing speed α1_B (hereinafter, referred to as the first valve closing speed α1_A as appropriate). In other words, the second first valve closing speed α1_B is set to a value smaller than the first first valve closing speed α1_A.

  Next, in step S37, the ECU 100 determines that the throttle opening (the actual opening of the throttle valve 36a) is less than the preset second throttle opening (reference opening) ETB2 and the intake pressure is set in advance. It is determined whether or not the pressure is less than the intake pressure P2.

  If the determination in step S37 is YES, ECU 100 proceeds to step S38. On the other hand, when the determination in step 37 is NO, the ECU 100 returns to step S36. In other words, the ECU 100 continues to close the throttle valve 36a at the late first valve closing speed α1_B until the throttle opening is less than the second throttle opening ETB2 and the intake pressure is less than the reference intake pressure P2.

  In step S38, the ECU 100 closes the throttle valve 36a at a preset second valve closing speed α2. Specifically, similarly to step S36, the target throttle opening is gradually reduced at the second valve closing speed α2, and thereby the opening of the throttle valve 36a is reduced at the second valve closing speed α2.

  The second valve closing speed α2 is set to a value lower than the first valve closing speed α1_B of the first period and the first valve closing speed α1_B of the second period, and after step S38, the throttle valve 36a is closed more slowly than before. It will be done.

  Next, in step S39, the ECU 100 determines whether or not the throttle valve 36a is fully closed. If the determination in step S38 is YES, ECU 100 proceeds to step S40. On the other hand, when the determination in step 39 is NO, the ECU 100 returns to step S38. That is, the ECU 100 continues to close the throttle valve 36a at the second valve closing speed α2 until the throttle valve 36a is fully closed (until the throttle opening becomes 0 degree).

  When the determination in step S40 is YES and the throttle valve 36a is fully closed, the ECU 100 maximizes the driving force of the throttle valve 36a and presses the throttle valve 36a to the fully closed position. In the present embodiment, the ECU 100 sets the drive duty of the valve actuator 36b to near 100% and presses the throttle valve 36a to the fully closed position.

  Step S40 is continued until any one of steps S23 to S25 becomes NO, and the sticking avoidance control is stopped accordingly. For example, step S40 is continued until the fuel return operation in which the fuel supply into the cylinder 2 is resumed and the fuel cut operation is completed.

  As described above, in this embodiment, when the execution of the sticking avoidance control is determined in step S26, first, the opening degree of the first EGR valve 52a is gradually increased. Then, when the opening degree of the first EGR valve 52a reaches the reference EGR opening degree E1, the closing of the throttle valve 36a is started. Then, the throttle valve 36a is closed until it is fully closed while the valve closing speed is gradually decreased in this order, the initial first valve closing speed α1_A, the latter first valve closing speed α1_b, and the second valve closing speed α2. The

  Next, a control procedure when the fuel return is performed after the sticking avoidance control is performed, that is, after the throttle valve 36a is fully closed in the fuel cut state will be described using the flowchart of FIG.

  First, in step S41, the ECU 100 determines whether or not the fuel is returned when the throttle valve 36a is fully closed. If this determination is NO, ECU 100 ends the process as it is (returns to normal control), and if YES, executes step S42 and the subsequent steps.

  In step S42, the ECU 100 opens the throttle valve 36a at a preset reference valve opening speed α10, and gradually increases the opening degree of the throttle valve 36a. The reference valve opening speed α10 is set to the same speed as the late first valve closing speed α1_B. Specifically, the reference valve opening speed α10 is set to a value whose absolute value is the same as the absolute value of the latter first valve closing speed α1_B.

  This step S42 is continued until the determination in step S45 described later becomes YES. That is, the throttle valve 36a continues to be opened at the reference valve opening speed α10 until the determination in step S45 becomes YES.

  Next, in step S43, the ECU 100 determines whether or not the intake pressure has become equal to or higher than a preset return reference intake pressure P10. In the present embodiment, the return reference intake pressure P10 is set to substantially the same value as the reference intake pressure P2.

  If the determination in step S43 is no, the process returns to step S42. That is, ECU 100 waits for the determination in step S43 to be YES while opening throttle valve 36a at reference valve opening speed α10.

  If the determination in step S43 is YES and the intake pressure increases to the return reference intake pressure P10 or higher, the ECU 100 proceeds to step S44 and starts closing the first EGR valve 52a. At this time, the ECU 100 sets the first EGR valve 52a to a reference EGR valve that is set in advance toward the opening E10 during normal control (the opening that is realized when the sticking avoidance control is not performed). The valve is closed at a speed β10. The reference EGR valve closing speed β10 is set to a value larger than the reference EGR valve opening speed β1. Specifically, the reference EGR valve closing speed β10 is set such that the absolute value thereof is larger than the absolute value of the reference EGR valve opening speed β1.

  Note that when the opening degree of the first EGR valve 52a during the normal control is fully open, the opening degree of the first EGR valve 52a is maintained fully open.

  The control in step S44 (control for closing the first EGR valve 52a) is continued until the opening degree of the first EGR valve 52a returns to the opening degree E10 during normal control. When the opening degree of the first EGR valve 52a returns to the opening degree E10 at the time of normal control, the control of the first EGR valve 52a is returned to the normal control. That is, the control of steps S1 to S6 shown in FIG. 4 is started for the first EGR valve 52a. The second EGR valve 52b is also returned to the normal control when the opening degree of the first EGR valve 52a returns to the opening degree during the normal control.

  Following step S44, the process proceeds to step S45, where the ECU 100 determines whether the opening of the throttle valve 36a has reached the first throttle opening ETB1. If this determination is YES, ECU 100 proceeds to step S46. That is, the ECU 100 continues the step S42 after the determination in step S41 becomes YES as described above, and continues to open the throttle valve 36a at the reference valve opening speed α10, and the opening degree of the throttle valve 36a is the first throttle. The process proceeds to step S46 after waiting for the opening ETB1 to be reached.

  In step S46, the ECU 100 opens the throttle valve 36a toward the opening during normal control (fully opened in the present embodiment). Specifically, if the determination in step S45 is YES, the ECU 100 changes the target throttle opening from the first throttle opening ETB1 stepwise to fully open, and opens the throttle valve 36a at a high speed. After the throttle valve 36a is fully opened, normal control is resumed for the control of the throttle valve 36a.

(3) Action, etc. FIG. 12 shows the time change of each parameter when the above sticking avoidance control is performed. FIG. 12 illustrates a case where acceleration is performed after the fuel cut is performed and the sticking avoidance control is performed in a state where the gear stage is maintained at the reference gear stage or higher. Further, FIG. 12 illustrates a case where the fuel is cut in the state where the first EGR valve 52a and the second EGR valve 52b are fully closed at the operation point X1 shown in FIG. Further, in FIG. 12, in order from the top, the vehicle speed, the injection amount, the intake pressure, the throttle opening (the solid line indicates the actual throttle opening, the chain line indicates the target throttle opening), and the opening of the first EGR valve 52a (the solid line indicates the actual opening). And the chain line indicates the change over time.

  As described above, in the present embodiment, the throttle valve 36a is fully opened in the normal throttle control except the intake throttle control and the sticking avoidance control, and before the start of the fuel cut at time t1. The throttle valve 36a is fully open.

  When the fuel cut is made at time t1, the vehicle speed and the intake pressure gradually decrease. When the intake pressure drops below the reference start pressure P1 at time t2, the sticking avoidance control is started, and first, the first EGR valve 52a is opened (step S31 is performed). The opening degree of the first EGR valve 52a gradually increases at the reference EGR valve opening speed β1 toward full opening.

  When the first EGR valve 52a is opened, the amount of recirculation of EGR gas to the intake passage 30 increases and the intake pressure may increase rapidly. However, in this embodiment, as described above, the opening degree of the first EGR valve 52a Is gradually increased, the sudden change in the intake pressure accompanying the change in the opening is suppressed. Therefore, the rate of decrease of the intake pressure is maintained substantially constant before and after time t2.

  Thereafter, when the opening degree of the first EGR valve 52a becomes equal to or greater than the reference EGR opening degree E1 at time t3 (when the determination in step S32 is YES), the target throttle opening degree is the first as shown by the chain line in FIG. The throttle opening ETB1 is set (step S33). Then, the closing of the throttle valve 36a is started toward the first throttle opening ETB1 (step S34).

  At this time, the target throttle opening is changed from fully open to the first throttle opening ETB1 stepwise, but the actual throttle opening does not change stepwise because there is a delay in the movement of the throttle valve 36a. As indicated by the solid line, the speed decreases toward the first throttle opening ETB1 at a predetermined speed (initial first valve closing speed α1_A). However, the initial first valve closing speed α1_A becomes relatively large as the target throttle opening changes stepwise.

  As described above, the area from the fully open position to the first throttle opening degree ETB1 is a dead zone. Therefore, after time t3, the intake pressure decreases at the same speed as before time t3.

  Thereafter, when the throttle opening reaches the first throttle opening ETB1 at time t4 (when the determination in step S35 is YES), the throttle valve 36a is closed at the late first valve closing speed α1_B. (Step S36). As described above, in the present embodiment, the target throttle opening is reduced at the late first valve closing speed α1_B, whereby the throttle valve 36a is closed at the late first valve closing speed α1_B.

  Since the dead zone is exceeded, after time t4, the intake pressure decreases at a faster speed than before time t4 as the throttle valve 36a is closed. However, since the late first valve closing speed α1_B is set to a value smaller than the initial first valve closing speed α1_A, the sudden decrease in the intake pressure is suppressed and the intake pressure gradually decreases. Further, in the present embodiment, as described above, the first EGR valve 52a is controlled to the open side so that a large amount of EGR gas recirculates to the intake passage 30. This also suppresses a sudden decrease in the intake pressure. The

  When the throttle opening decreases to less than the second throttle opening ETB2 at time t5 and the intake pressure becomes less than the reference intake pressure P2 (when the determination in step S37 is YES), the throttle opening is fully closed at time t6. The throttle valve 36a is closed at the second valve closing speed α2 (step S38). As described above, in the present embodiment, the target throttle opening is reduced at the second valve closing speed α2, and thereby the throttle valve 36a is closed at the second valve closing speed α2.

  As described above, since the second valve closing speed α2 is smaller than the late first valve closing speed α1_B, as shown in FIG. 12, the throttle opening gradually decreases until fully closed at time t6. .

  Here, from time t5 to time t6, since the throttle opening is very small, less than the second throttle opening ETB2, the sensitivity of the intake pressure with respect to the throttle opening is high (the intake with respect to the unit change amount of the throttle opening). The amount of change in atmospheric pressure is large), and the intake pressure tends to decrease rapidly as the throttle opening decreases.

  On the other hand, in the present embodiment, as described above, the throttle valve 36a is closed at the relatively slow second valve closing speed α2 during this period, so the intake pressure accompanying the closing of the throttle valve 36a is reduced. Sudden decline is suppressed.

  Further, in the present embodiment, after the intake pressure drops below the reference intake pressure P2 at time t5, that is, after the difference from the intake pressure when the throttle valve 36a is fully closed becomes less than a predetermined value, the throttle Since the valve 36a is closed to the fully closed state at the second valve closing speed α2 that is relatively slow, this also suppresses a sudden decrease in the intake pressure from the time t5 to the time t6.

  Therefore, in the present embodiment, during the period from time t5 to time t6, the intake pressure decreases at a faster speed than before time t5, but the decrease speed is kept small, and the intake pressure gradually decreases without sudden change. I will do it.

  In addition, during the period from time t5 to time t6, the first EGR valve 52a is controlled to be opened as in the period from time t4 to time t5, so that a large amount of EGR gas returns to the intake passage 30. This also suppresses a sudden decrease in the intake pressure.

  In the example shown in FIG. 12, the opening degree of the first EGR valve 52a reaches full open at time t5. In other words, the first EGR valve 52a is controlled to be fully opened around time t5.

  Although not shown in FIG. 12, when the throttle valve 36a is fully closed at time t6, the driving force of the throttle valve 36a is maximized (step S40), and the driving force is maximized until acceleration is started at time t7. In this state, the throttle valve 36a is kept fully closed.

  When acceleration is started at time t7 and fuel recovery is performed (when the determination in step S41 is YES), first, the throttle valve 36a is opened (step S42). At this time, the opening degree of the throttle valve 36a is opened relatively slowly at the reference valve opening speed α10 whose absolute value is the same as the latter first valve closing speed α1_B.

  As described above, the throttle valve 36a is opened relatively slowly so that the intake pressure gradually increases after time t7.

  Thereafter, when the intake pressure becomes equal to or higher than the return reference intake pressure P3 at time t8 (when the determination in step S43 is YES), the first EGR valve 52a is closed toward the opening E10 during normal control. At this time, the first EGR valve 52a is closed so that the valve closing speed becomes the reference EGR valve closing speed β10 set to a value larger than the reference EGR valve opening speed β1.

  In the example shown in FIG. 12, the first EGR valve 52a is also set with a dead zone region (a region where the flow rate of the EGR gas hardly changes even when the opening degree of the first EGR valve 52a is changed). The first EGR valve 52a is closed relatively early for the dead zone region, and then is closed toward the opening during normal control.

  Here, when the opening degree of the first EGR valve 52a is changed, the EGR gas amount and the intake pressure change. In the present embodiment, the opening degree of the first EGR valve 52a is gradually changed as described above. It is possible to suppress a sudden change in the intake pressure before and after t8.

  Thereafter, when the throttle opening reaches the first throttle opening ETB1 at time t9 (when the determination in step S45 is YES), the throttle valve 36a is moved from the reference valve opening speed α10 toward the normal opening, that is, fully opened. Is also opened at high speed. Specifically, the target throttle opening is fully opened, and the opening of the throttle valve 36a is changed toward this.

  As described above, in this embodiment, the sticking avoidance control for fully closing the throttle valve 36a is performed during the fuel cut operation and when the engine body 1 is in operation. Therefore, many opportunities to fully close the throttle valve 36a can be secured, and the soot C accumulated around the throttle valve 36a can be appropriately removed to prevent the throttle valve 36a from sticking.

  In addition, in this sticking avoidance control, the first valve closing speed is relatively fast until the timing (time t5) when the opening of the throttle valve 36a is reduced below the reference opening ETB2 and the intake pressure is reduced below the reference intake pressure P2. While the throttle valve 36a is closed at α1 (initial first valve closing speed α1_A and late first valve closing speed α1_B), after this timing, the throttle valve is closed at a second valve closing speed α2 that is slower than the first valve closing speed α1. The valve 36a is closed. Therefore, it is possible to prevent the intake pressure from excessively decreasing even in the operating state in which the intake pressure is likely to rapidly decrease as described above, while bringing the throttle valve 36a to close fully earlier. Therefore, it is possible to suppress the rate of change of the intake pressure from becoming excessively large, and accompanying this, the pumping loss rapidly increases and the deceleration of the engine body 1 and the vehicle rapidly increase.

  In particular, in this embodiment, the superchargers 60 and 70 are provided, and the intake pressure is controlled to a high value. For this reason, the fluctuations in the intake pressure accompanying the change in the opening of the throttle valve 36a, and hence the fluctuations in the deceleration of the engine body 1 and the vehicle tend to be large. Therefore, by performing the above-described sticking avoidance control, it is possible to effectively suppress a rapid increase in the deceleration of the engine body 1 and the vehicle while the throttle valve 36a is fully closed.

  In the present embodiment, the initial first valve closing speed α1_A is made larger than the late first valve closing speed α1_B, and after the sticking avoidance control is performed, the throttle opening is decreased to the first ETB opening ETB1. The throttle valve 36a is closed at a higher speed under operating conditions (in the present embodiment, the dead zone region) where the sensitivity of the intake pressure to the throttle opening is low. Therefore, the throttle valve 36a opening degree can be fully closed earlier while suppressing a rapid increase in the deceleration of the engine body 1 and the vehicle. As a result, even when the fuel cut time is short, removal of soot C can be realized, and many opportunities for this removal can be secured.

  In the present embodiment, the throttle valve 36a is fully closed even when the engine body 1 is stopped. Therefore, the opportunity for removal of soot C can be increased.

  Further, it is estimated that the accumulated amount of soot C has become a predetermined amount or more when the travel distance of the vehicle exceeds the reference distance after the throttle valve 36a is fully closed, including when the engine body 1 is stopped. Only in such a case, the sticking avoidance control is performed. Therefore, it is possible to reduce the chance of increasing the deceleration of the engine body 1 and the vehicle along with the execution of the sticking avoidance control by appropriately removing the bag C and suppressing the sticking avoidance control.

  Further, in this embodiment, when the gear stage is a high speed stage that is equal to or higher than the reference gear stage and the sensitivity of the vehicle deceleration to the deceleration of the engine body 1 is low (the vehicle speed associated with the change in the deceleration of the engine body 1). Since the sticking avoidance control is executed only when the change amount of the deceleration is small), even if the deceleration of the engine body 1 is changed by executing the sticking avoidance control, the accompanying vehicle deceleration is suppressed sufficiently small. And the ride comfort of the vehicle can be improved.

  In the present embodiment, the sticking avoidance control is performed only when the intake pressure is less than the reference start pressure P1. In other words, the sticking avoidance control is performed only when the intake pressure is relatively low and the amount of decrease (decrease amount) in the intake pressure that accompanies closing the throttle valve 36a to the fully closed state and hence the deceleration of the engine body can be kept small. The Therefore, the rapid increase in the deceleration of the engine body due to the implementation of the sticking avoidance control can be more reliably suppressed.

  In the present embodiment, the first EGR valve 52a is controlled to the open side during the sticking avoidance control. In particular, the opening is controlled to be more open than the opening during normal control. Therefore, during the sticking avoidance control, more EGR gas can be recirculated to the intake passage 30, and the intake pressure can be increased even if the intake amount (fresh air amount) decreases as the throttle valve 36a is closed. The exhaust pressure can be lowered to suppress a rapid increase in pumping loss. Therefore, a rapid increase in the deceleration of the engine body can be more reliably suppressed.

  In particular, in the present embodiment, the closing of the throttle valve 36a is started after the first EGR valve 52a is opened. Therefore, the increase in intake pressure and pumping loss at the start of closing of the throttle valve 36a can be further suppressed.

  Further, in this embodiment, the throttle valve 36a is fully opened (opening during normal operation) when the fuel is returned after the throttle valve 36a is fully closed in accordance with the sticking avoidance control. It is gradually increased toward. Therefore, even at the time of this fuel return, it is possible to suppress a sudden change in the intake pressure with a change in the opening of the throttle valve 36a, and it is possible to suppress a sudden change in the movement of the engine body 1 and the vehicle.

(4) Modification In the above embodiment, the case where the initial first valve closing speed α1_A and the late first valve closing speed α1_B are set to different speeds has been described, but these speeds are larger than the second valve closing speed α2. You may set to the same value. However, as described above, if the initial first valve closing speed α1_A, which is the valve closing speed of the throttle valve 36a immediately after the start of closing of the throttle valve 36a and the intake pressure is high, is set to a larger value, the engine body 1 and the throttle valve 36a can be fully closed early while suppressing a sudden increase in the deceleration of the vehicle.

  In the above embodiment, in the sticking avoidance control, the case where the valve opening of the throttle valve 36a is started after the opening of the first EGR valve 52a is started has been described, but these may be started simultaneously. That is, the closing of the throttle valve 36a may be started when the intake pressure is reduced below the reference start pressure P1.

  In the above embodiment, the case where the first EGR valve 52a is opened instead of the second EGR valve 52b when the sticking avoidance control is performed is described. However, at least one of these valves 52a and 52b is in the normal control. The valve may be opened more than the opening degree.

  However, when the fuel cut and the sticking avoidance control are performed in a state where the temperature of the exhaust such as a high load is high, opening the second EGR valve 52b is not preferable because high-temperature exhaust is introduced into the second EGR valve 52b. . On the other hand, the first EGR valve 52a is introduced with a relatively low temperature exhaust gas after being cooled by the EGR cooler 55. Therefore, if only the first EGR valve 52a is opened when the sticking avoidance control is performed, the reliability of the valves 52a and 52b can be ensured.

  In addition, when the sticking avoidance control is performed, the control for opening the first EGR valve 52a beyond the opening during normal control may be omitted. However, if this control is performed, as described above, the pumping loss can be further reduced when the sticking avoidance control is performed.

  Further, when the throttle valve 36a is fully closed when the intake pressure is high with supercharging, the amount of decrease in the intake pressure is lower than when the throttle valve 36a is fully closed when the intake pressure is low. Becomes larger and the deceleration of the engine body 1 tends to increase rapidly. Therefore, in the above-described embodiment, the case where it is determined whether or not the sticking avoidance control is performed regardless of the operation state before the fuel cut has been described, but instead of this, supercharging is performed in the fuel cut. More specifically, when the fuel cut operation is started, the throttle valve 36a is fully closed while varying the valve closing speed only during the fuel cut operation from the state where at least one of the valves 41a and 42a is closed. The sticking avoidance control may be performed so that the throttle valve 36a is fully closed at a constant speed and a relatively fast speed during other fuel cut operations. In this way, a rapid increase in the deceleration of the engine body 1 can be effectively suppressed.

1 Engine body 30 Intake passage 36a Throttle valve 51 EGR passage 51a First EGR passage (EGR passage)
51b Second EGR passage (EGR passage)
52a First EGR valve (EGR valve)
52b Second EGR valve (EGR valve)
SE3 Intake pressure sensor (intake pressure detection means)
100 ECU (throttle control means, EGR control means)
α1_A Initial first valve closing speed (first valve closing speed)
α1_B Late first valve closing speed (first valve closing speed)
α2 Second valve closing speed ETB1 First throttle opening (intermediate setting opening)
ETB2 Second throttle opening (reference opening)
P1 Reference start pressure P2 Reference pressure

Claims (7)

An apparatus for controlling an engine mounted on a vehicle, comprising an intake passage for allowing intake air to flow into an engine body and a throttle valve for opening and closing the intake passage,
An intake pressure detecting means capable of detecting an intake pressure which is a pressure in a portion downstream of the throttle valve in the intake passage;
The fuel supply to the engine main body is determined whether the fuel cut operation is stopped, whether the vehicle is required to carry out the sticking prevention control that makes closing the throttle valve to the fully closed A determination means for determining based on the travel distance;
Throttle control means for performing the sticking avoidance control based on a determination result by the determination means, or for performing normal control for setting the opening of the throttle valve to an opening on the opening side of the fully closed state. Prepared,
The throttle control means includes
When it is determined by the determination means that there is no execution request for the sticking avoidance control, or when it is determined that it is not during fuel cut operation even if there is the execution request, the normal control is performed,
When the determination means determines that there is a request to perform the sticking avoidance control and that the fuel cut operation is being performed, the sticking avoidance control is performed, and
The throttle control means, from the start of closing of the throttle valve during the performance of the sticking prevention control, the throttle valve opening degree becomes smaller than the reference opening degree previously set且one upper Symbol intake pressure detecting means The throttle valve is closed at the first valve closing speed until a specific time when the intake pressure detected in step S is less than a preset reference pressure, and after the specific time, the throttle valve is closed at the first valve closing time. A control device for an engine, wherein the valve is closed until it is fully closed at a second valve closing speed smaller than the speed. The engine control device according to claim 1,
As the first valve closing speed, an initial first valve closing speed and a late first valve closing speed smaller than the initial first valve closing speed and larger than the second valve closing speed are set,
The throttle control means starts the closing of the throttle valve during execution of the sticking avoidance control, and then performs an intermediate setting opening in which the opening of the throttle valve is preset as an opening higher than the reference opening. The throttle valve is closed at the initial first valve closing speed until the throttle valve is opened, and the throttle valve is opened in the latter period until the specific time after the throttle valve opening reaches the intermediate set opening. An engine control device that closes at a first valve closing speed and closes at a second valve closing speed until it is fully closed after the specified time . The engine control apparatus according to claim 1 or 2,
When the fuel supply to the engine body is resumed after the throttle valve is fully closed as the sticking avoidance control is performed, the throttle control means opens the throttle valve more fully. An engine control device characterized by gradually increasing toward a target opening set on the side. The engine control device according to claim 3,
When the throttle control means gradually increases the throttle valve opening from fully closed as the fuel supply is resumed, the throttle valve opening means the absolute value of the throttle valve opening from the absolute value of the first valve closing speed. The engine control apparatus is characterized by increasing at a high speed. The engine control apparatus according to any one of claims 1 to 4 ,
The throttle control means controls the opening of the throttle valve to be fully closed even when the engine body is stopped,
It said determining means includes determining means determines that the can and running distance of the vehicle the opening of the throttle valve from the fully closed becomes a preset reference distance or more is execution request of the fixation avoiding control The engine control device. The engine control apparatus according to any one of claims 1 to 5 ,
The throttle control means, there are carried out the request of the sticking prevention control and even when it is determined that the fuel cut operation, the upper Symbol secured in the case of less than the reference shift speed gear position is set in advance An engine control device that prohibits execution of avoidance control. The engine control apparatus according to any one of claims 1 to 6 ,
An EGR passage that recirculates part of the exhaust discharged from the engine body to the intake passage;
An EGR valve that opens and closes the EGR passage;
An engine control apparatus, comprising: EGR control means for controlling the opening degree of the EGR valve to open more than that during normal operation when the sticking avoidance control is performed.

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