JP2016217286A - Control device of engine system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a pumping loss at the deceleration of an engine, and to suppress the deterioration of a catalyst caused by oxygen.SOLUTION: A control device of an engine system comprises: an engine 1; an intake passage 4; a throttle device 7: an exhaust passage 5; a catalyst 10a; a port injector 32 and an in-cylinder injector 33; a second EGR passage 57 which makes a part of exhaust emission flow to the intake passage 4 as an EGR gas, and makes it flow back to the engine 1; a second EGR valve 58 opening and closing the second EGR passage 57; and an electronic control device (ECU) 50. An inlet 57a of the second EGR passage 57 communicates with the exhaust passage 5 at an upstream side rather than the catalyst 10a, and an outlet 57b communicates with the intake passage 4 at a downstream side rather than the throttle device 7. When there is a deceleration fuel cut requirement, the ECU 50 valve-opening controls the second EGR valve 58, valve-closing controls the throttle device 7, and stop-controls the injectors 32, 33 on the basis of an EGR arrival time up to a time at which the EGR gas arrives at the intake passage 4 via the second EGR passage 57 in order to stop fuel supply to the engine 1.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a control device for an engine system configured to recirculate a part of exhaust discharged from an engine as exhaust gas recirculation gas to the engine and to stop fuel supply to the engine when there is a request for deceleration to the engine. .

  Conventionally, as this type of technique, for example, a technique described in Patent Document 1 below is known. In this technique, a catalyst for purifying exhaust gas is provided in the exhaust passage of the engine. An EGR passage that recirculates exhaust gas recirculation gas (hereinafter referred to as “exhaust gas recirculation”) to the engine has an inlet connected to an exhaust passage downstream of the catalyst and an outlet of an intake passage (intake air downstream of the throttle valve). Connected to the branch pipe). An EGR valve that adjusts the flow rate of EGR gas is provided in the EGR passage. When a deceleration request for the engine is detected, the fuel supply to the engine by the fuel injection valve is stopped, that is, the fuel cut is executed, the EGR valve is opened, and the EGR gas is returned to the engine via the EGR passage. Configured to let As a result, the pumping loss of the engine is reduced when the engine is decelerated.

JP 2010-116870 A

  However, in the technique described in Patent Document 1, although the pumping loss of the engine can be reduced when the engine is decelerated, the fresh air (oxygen) remaining in the intake passage downstream of the throttle valve and the fuel cut inside the cylinder are cut off. Oxygen may flow to the catalyst, which may cause the catalyst to deteriorate.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to reduce the pumping loss of the engine and suppress the deterioration of the catalyst due to oxygen when the engine is decelerated. It is to provide a control device.

  In order to achieve the above object, an invention according to claim 1 is directed to an intake passage for introducing intake air into an engine, an intake air amount adjusting valve for adjusting an intake air amount in the intake passage, and exhaust gas from the engine. An exhaust passage, a catalyst for purifying exhaust flowing in the exhaust passage, a fuel supply means for supplying fuel to the engine, and a part of the exhaust led out from the engine to the exhaust passage as exhaust recirculation gas The exhaust gas recirculation passage for flowing into the intake passage and recirculating to the engine, and the exhaust gas recirculation passage include an inlet and an outlet, the inlet communicates with the exhaust passage upstream of the catalyst, and the outlet communicates with the intake passage downstream of the intake air amount adjustment valve And a control device for an engine system comprising an exhaust gas recirculation valve for opening and closing the exhaust gas recirculation passage and a control means for controlling the operation of the engine. When there is a deceleration fuel cut request, the exhaust recirculation valve is controlled to open and the intake air amount adjustment valve is controlled to close, and the time until the exhaust recirculation gas reaches the intake passage via the exhaust recirculation passage is reached. If time is taken, the fuel supply means is controlled to stop based on the exhaust gas recirculation arrival time in order to stop the fuel supply to the engine.

  According to the configuration of the above invention, when there is a deceleration fuel cut request for the engine, the control means controls to open the exhaust gas recirculation valve and closes the intake air amount adjustment valve. As a result, the flow of fresh air (oxygen) into the intake passage downstream from the intake air amount adjustment valve is blocked, and part of the exhaust led out from the engine to the exhaust passage does not flow to the catalyst, but the exhaust gas recirculation passage To the intake passage and returned to the engine. The control means stops the fuel supply means based on the exhaust gas recirculation arrival time until the exhaust gas recirculation gas reaches the intake passage via the exhaust gas recirculation passage. Therefore, since the fuel supply to the engine is stopped when the intake passage downstream of the intake air amount adjusting valve is filled with the recirculated exhaust gas recirculation gas, the inflow of oxygen to the catalyst is suppressed thereafter.

  In order to achieve the above object, according to a second aspect of the present invention, in the first aspect of the present invention, the engine is a four-cycle reciprocating engine, has a plurality of cylinders, and the fuel supply means is provided for each cylinder. A plurality of pre-cylinder injection valves that inject fuel into the intake passage immediately before the engine, and when there is a deceleration fuel cut request for the engine, the control means opens the exhaust gas recirculation valve and then the exhaust gas recirculation arrival time has elapsed In the preceding stage, the stop control is started from the cylinder pre-injection valve of the cylinder in the exhaust stroke most recently, and the cylinder pre-injection valve is sequentially controlled to stop when the other cylinders are also in the exhaust stroke.

  According to the configuration of the above invention, in addition to the operation of the invention according to claim 1, the control means controls the opening of the exhaust gas recirculation valve after the deceleration fuel cut request for the engine, and then the exhaust gas recirculation arrival time has elapsed. In the previous stage, stop control is started from the cylinder pre-injection valve of the cylinder most recently in the exhaust stroke, and the cylinder pre-injection valve is sequentially controlled to stop when the other cylinders are also in the exhaust stroke. Therefore, when the intake passage downstream of the intake air amount adjustment valve is filled with the recirculated exhaust gas recirculation gas, the fuel supply to the cylinder that becomes the exhaust stroke is stopped, so that the inflow of oxygen to the catalyst is suppressed thereafter. It is done.

  In order to achieve the above object, according to a third aspect of the present invention, in the first aspect of the present invention, the engine is a four-cycle reciprocating engine, and has a plurality of cylinders. A plurality of in-cylinder injection valves that directly inject fuel into the cylinder, and when there is a deceleration fuel cut request to the engine, the control means controls the opening of the exhaust gas recirculation valve, and then immediately after the exhaust gas recirculation arrival time has elapsed. The intent is to start the stop control from the in-cylinder injection valve of the cylinder in the intake stroke and to sequentially stop the in-cylinder injection valves when the other cylinders are also in the intake stroke.

  According to the configuration of the above invention, in addition to the operation of the invention according to claim 1, the control means controls the opening of the exhaust gas recirculation valve after the deceleration fuel cut request for the engine, and then the exhaust gas recirculation arrival time has elapsed. After that, the stop control is started from the in-cylinder injection valve of the cylinder in the intake stroke most recently, and the in-cylinder injection valves are sequentially controlled to stop when the other cylinders are also in the intake stroke. Therefore, when the intake passage downstream of the intake air amount adjustment valve is filled with the recirculated exhaust gas recirculation gas, the fuel supply to the cylinder that becomes the intake stroke is stopped, so that the inflow of oxygen to the catalyst is subsequently suppressed. It is done.

  To achieve the above object, according to a fourth aspect of the present invention, in the third aspect of the present invention, when the control means starts the stop control from the cylinder front injection valve of the cylinder in the exhaust stroke, The purpose is to perform injection control of the in-cylinder injection valve in the other cylinders in the exhaust stroke at the same timing as the intake stroke.

  According to the configuration of the above invention, in addition to the operation of the invention according to claim 3, when the control means starts the stop control from the cylinder front injection valve of the cylinder in the exhaust stroke, the same timing as the intake stroke of the cylinder Since the in-cylinder injection valve is controlled to be injected in the other cylinder in the exhaust stroke, the fuel is mixed with the exhaust led to the exhaust passage. Therefore, fuel flows to the catalyst as the exhaust flows to the catalyst.

  In order to achieve the above object, according to a fifth aspect of the present invention, in the first aspect of the present invention, a part of the exhaust led out from the engine to the exhaust passage is flowed to the intake passage as exhaust recirculation gas to the engine. The separate exhaust gas recirculation passage for recirculation and the separate exhaust gas recirculation passage include a separate inlet and a separate outlet, the separate inlet communicates with the exhaust passage downstream of the catalyst, and the separate outlet is connected to the intake passage downstream of the intake air amount adjustment valve. And further comprising another exhaust gas recirculation valve for adjusting the flow rate of the exhaust gas recirculation gas in the separate exhaust gas recirculation passage, and the control means separates another exhaust gas recirculation when there is a deceleration fuel cut request for the engine. The purpose is to control the opening of another exhaust gas recirculation valve as needed during normal operation where the valve is controlled to close and there is no deceleration fuel cut request.

  According to the configuration of the above invention, in addition to the operation of the invention according to claim 1, when there is a deceleration fuel cut request for the engine, the control means controls the closing of another exhaust gas recirculation valve. Is recirculated to the engine only through the exhaust gas recirculation passage. In addition, during normal operation where there is no deceleration fuel cut request, the control means controls opening of another exhaust gas recirculation valve as necessary. Therefore, during normal operation, part of the exhaust gas that has passed through the catalyst is used as exhaust gas recirculation gas. It is returned to the engine through another exhaust gas recirculation passage.

  In order to achieve the above object, according to a sixth aspect of the invention, in the invention of the second or third aspect, each cylinder includes an intake port communicating with the intake passage and an exhaust port communicating with the exhaust passage. The intake valve is provided with an exhaust valve at the exhaust port, and the intake valve and the exhaust valve are driven to open and close in conjunction with the operation stroke of the engine to change the valve overlap between the intake valve and the exhaust valve. A timing mechanism is further provided, and the control means controls the variable valve timing mechanism so as to increase the valve overlap as the engine speed increases when the exhaust gas recirculation valve is controlled to open according to the deceleration fuel cut request for the engine. The purpose is to do.

  According to the configuration of the above invention, in addition to the operation of the invention according to claim 2 or 3, when the control means controls the opening of the exhaust gas recirculation valve in response to the deceleration fuel cut request for the engine, the engine speed is reduced. The higher the value, the more variable valve timing mechanism is controlled to increase the valve overlap. Therefore, the exhaust gas recirculation gas flow rate that is insufficient in the high rotational speed region is compensated by internal exhaust gas recirculation that occurs in each cylinder due to valve overlap.

  According to the invention of any one of claims 1 to 3, it is possible to reduce the pumping loss of the engine when the engine is decelerated and to suppress the deterioration of the catalyst due to oxygen.

  According to the invention described in claim 4, in addition to the effect of the invention described in claim 3, it is possible to suppress the leaning of the catalyst.

  According to the invention described in claim 5, in addition to the effect of the invention described in claim 1, when the fuel supply to the engine is stopped, the exhaust gas recirculation is made relatively quickly by using the exhaust gas recirculation passage having a short path. Gas can be recirculated, and during normal operation of the engine, exhaust gas purified by the catalyst can be recirculated to the engine as exhaust gas recirculation gas.

  According to the invention described in claim 6, in addition to the effect of the invention described in claim 2 or 3, it is possible to prevent the intake pressure from becoming a high negative pressure and to prevent oil from rising in the engine. Can do.

1 is a schematic configuration diagram illustrating an engine system according to a first embodiment. 4A and 4B are schematic diagrams illustrating valve overlap between an intake valve and an exhaust valve according to the first embodiment. The flowchart which concerns on 1st Embodiment and shows the processing content of deceleration control. FIG. 5A is a time chart illustrating an example of changes in various parameters related to deceleration control according to the first embodiment. The flowchart which concerns on 2nd Embodiment and shows the processing content of deceleration control. FIG. 5A is a time chart illustrating an example of changes in various parameters related to deceleration control according to the second embodiment. The flowchart which shows the processing content of deceleration control concerning 3rd Embodiment. The graph which shows the relationship of the intake pressure with respect to an engine rotational speed at the time of making the maximum flow volume of a 2nd EGR valve match with the required flow volume of a low rotational speed area according to 3rd Embodiment. The graph which shows the relationship of the displacement amount of VVT with respect to the engine speed in the same case concerning 3rd Embodiment. The graph which shows the relationship of the intake pressure with respect to an engine rotational speed at the time of making the maximum flow volume of a 2nd EGR valve match with the request | required flow volume of a high rotational speed area according to 3rd Embodiment. The graph which shows the relationship of the displacement amount of VVT with respect to engine speed in the same case concerning 3rd Embodiment.

<First Embodiment>
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a first embodiment in which an engine system control device according to the present invention is embodied will be described in detail with reference to the drawings.

  FIG. 1 is a schematic configuration diagram showing an engine system of this embodiment. In this embodiment, the engine 1 mounted on the automobile is a four-cycle reciprocating engine and includes four cylinders 2 and a crankshaft 3. The engine 1 is provided with an intake passage 4 for introducing intake air into the engine 1 and an exhaust passage 5 for leading exhaust from the engine 1. An air cleaner 6, an electronic throttle device 7, and an intake manifold 8 are provided in the intake passage 4 from the upstream side. The electronic throttle device 7 includes a throttle valve 9 that is opened and closed by a motor 31 and a throttle sensor 41 for detecting an opening degree (throttle opening degree) TA of the throttle valve 9. The electronic throttle device 7 corresponds to an example of an intake air amount adjustment valve of the present invention for adjusting the intake air amount in the intake passage 4. The intake manifold 8 includes a surge tank 8a. The exhaust passage 5 is provided with a catalytic converter 10 and the like for purifying the exhaust gas flowing through the passage 5. The catalytic converter 10 incorporates a three-way catalyst 10a made of a noble metal.

  The engine 1 includes a cylinder block 11 and a cylinder head 12. The cylinder block 11 includes each cylinder 2, and each cylinder 2 is provided with a piston 13. Each piston 13 is connected to the crankshaft 3 via a connecting rod 14. Each cylinder 2 includes a combustion chamber 15. The combustion chamber 15 is formed between the piston 13 and the cylinder head 12 in each cylinder 2. The cylinder head 12 is formed with an intake port 16 and an exhaust port 17 communicating with the combustion chamber 15 of each cylinder 2. Each intake port 16 communicates with the intake passage 4 (intake manifold 8). Each exhaust port 17 communicates with the exhaust passage 5. Each intake port 16 is provided with an intake valve 18, and each exhaust port 17 is provided with an exhaust valve 19. Each intake valve 18 and each exhaust valve 19 are interlocked with the rotation of the crankshaft 3, that is, interlocking with the vertical movement of each piston 13, and as a result, a series of operation strokes (intake stroke, compression stroke, The valve is driven to open and close by a valve mechanism including camshafts 20 and 21 in conjunction with an explosion stroke and an exhaust stroke. The intake valve 18 is driven to open and close by an intake camshaft 20, and the exhaust valve 19 is driven to open and close by an exhaust camshaft 21.

  In this embodiment, the intake-side camshaft 20 is provided with an electric variable valve timing mechanism (hereinafter simply referred to as “VVT”) 22. The VVT 22 is configured such that the opening / closing timing (valve timing) that is the opening / closing characteristics of the intake valve 18 can be changed. That is, the VVT 22 is configured to advance and retard the valve timing of the intake valve 18 within a predetermined range by being driven by an attached motor (not shown). Thus, the valve overlap between the intake valve 18 and the exhaust valve 19 can be changed. Since the structure of the VVT 22 is already known, a description thereof is omitted here.

  Here, the valve overlap by the VVT 22 will be described. 2A and 2B are schematic diagrams showing valve overlap between the intake valve 18 and the exhaust valve 19. The valve overlap means a state in which the intake port 16 and the exhaust port 17 are simultaneously opened in the reciprocating type engine 1. Further, the valve overlap is usually set for the purpose of improving the intake charging efficiency by opening the intake port 16 by the intake valve 18 just before the end of the exhaust stroke of the engine 1. If the valve overlap is widened, the substantial compression ratio of the engine 1 is lowered, so that abnormal combustion such as knocking can be prevented. On the contrary, if the valve overlap is narrowed, the charging efficiency of the air-fuel mixture in the low rotation speed region of the engine 1 becomes high, and stable combustion in the air-fuel mixture can be obtained even at low load and low speed. In addition to the output surface of the engine 1, by using valve overlap, internal EGR can be obtained in the engine 1, and pumping loss can be reduced in addition to exhaust purification. Also contribute. Although the appropriate timing for performing the internal EGR differs depending on the rotational speed and load of the engine 1, the valve overlap can be performed at the optimal timing by the VVT 22.

  Then, by operating the VVT 22 to advance the rotational phase of the intake camshaft 20 relative to that of the crankshaft 3, the valve timing phase of the intake valve 18 is advanced relative to the rotational phase of the crankshaft 3. In this case, as shown in FIG. 2B, the valve timing of the intake valve 18 is relatively advanced, and the valve overlap between the intake valve 18 and the exhaust valve 19 in the intake stroke becomes relatively large. At this time, the valve overlap is maximized by making the valve timing of the intake valve 18 the most advanced by the VVT 22. On the other hand, by operating the VVT 22 to delay the rotational phase of the intake camshaft 20 from that of the crankshaft 3, the phase of the valve timing of the intake valve 18 is retarded from the rotational phase of the crankshaft 3. Is done. In this case, as shown in FIG. 2A, the valve timing of the intake valve 18 is relatively delayed, and the valve overlap in the intake stroke becomes relatively small. At this time, by making the valve timing of the intake valve 18 the most retarded by the VVT 22, the valve overlap is minimized (eliminated).

  The cylinder head 12 is provided with a port injector 32 for injecting fuel (port injection) into each intake port 16 corresponding to each cylinder 2. Each port injector 32 is configured to inject fuel supplied from a fuel supply device (not shown), and corresponds to an example of fuel supply means and a pre-cylinder injection valve of the present invention. The cylinder block 11 is provided with in-cylinder injectors 33 for directly injecting fuel (in-cylinder injection) into each cylinder 2 (each combustion chamber 15) corresponding to each cylinder 2. Each in-cylinder injector 33 is configured to inject fuel supplied from a fuel supply device (not shown), and corresponds to an example of a fuel supply unit and an in-cylinder injection valve of the present invention. In each combustion chamber 15, a combustible air-fuel mixture is formed by the fuel injected from at least one of the port injector 32 and the in-cylinder injector 33 and the air sucked from the intake manifold 8 in the intake stroke or the like. In this embodiment, port injection by the port injector 32 is performed when each cylinder 2 is in the exhaust stroke. In-cylinder injection by the in-cylinder injector 33 is performed when each cylinder 2 is in the intake stroke.

  The cylinder head 12 is provided with a spark plug 36 corresponding to each cylinder 2. Each spark plug 36 performs a spark operation in response to an ignition signal output from the ignition coil 37. Both parts 36 and 37 constitute an ignition device that ignites a combustible air-fuel mixture in each combustion chamber 15. The combustible air-fuel mixture in each combustion chamber 15 explodes and burns by the spark operation of each spark plug 36 in the compression stroke, and the explosion stroke passes. Exhaust gas after combustion is discharged from each combustion chamber 15 through the exhaust port 17, the exhaust passage 5, the catalytic converter 10 and the like in the exhaust stroke. As described above, the combustion of the combustible air-fuel mixture in each combustion chamber 15 causes each piston 13 to move up and down, a series of operation strokes progress, and the crankshaft 3 rotates, thereby obtaining power for the engine 1. In the engine 1, the crankshaft 3 rotates twice (720 ° A rotation) every time a series of operation strokes is completed once in each cylinder 2.

  In the engine 1, an exhaust gas recirculation device (EGR device) 51 that causes a part of the exhaust gas led out from the combustion chamber 15 to flow into the intake passage 4 as an exhaust gas recirculation gas (EGR gas) and recirculates it to the combustion chamber 15. Is provided. This EGR device 51 is provided in a first exhaust gas recirculation passage (first EGR passage) 52 through which EGR gas flows, and a first exhaust gas recirculation for adjusting the flow rate of EGR gas in the first EGR passage 52. A valve (first EGR valve) 53 and an exhaust gas recirculation cooler (EGR cooler) 54 provided in the first EGR passage 52 for cooling the EGR gas are provided. An inlet 52 a of the first EGR passage 52 is connected to the exhaust passage 5 downstream from the catalytic converter 10 and communicates with the exhaust passage 5. The outlet 52b of the first EGR passage 52 is connected to the intake manifold 8 downstream of the electronic throttle device 7 and the surge tank 8a. The first EGR valve 53 is an electrically operated valve that is electrically controlled so as to have a variable opening. The first EGR passage 52 is provided with a bypass passage 55 that bypasses the EGR cooler 54, and the bypass passage 55 is provided with a bypass valve 56 for controlling the flow of EGR gas. The bypass valve 56 is an electric valve whose opening degree is electrically controlled. The first EGR passage 52 corresponds to an example of another exhaust gas recirculation passage of the present invention, and its inlet 52a and outlet 52b correspond to an example of another inlet and another outlet of the present invention, respectively. The first EGR valve 53 corresponds to an example of another exhaust gas recirculation valve of the present invention.

  The EGR device 51 also includes a second exhaust gas recirculation passage (second EGR passage) through which a part of the exhaust gas led out from each combustion chamber 15 to the exhaust passage 5 flows as an EGR gas to the intake passage 4 to be recirculated to the combustion chamber 15. A passageway 57 is further provided. The second EGR passage 57 is provided with a second exhaust recirculation valve (second EGR valve) 58 for opening and closing the passage 57. The second EGR passage 57 and the second EGR valve 58 mainly function to recirculate the EGR gas during the deceleration operation of the engine 1 accompanied by fuel cut (F / C). An inlet 57 a of the second EGR passage 57 is connected to the exhaust passage 5 upstream from the catalytic converter 10. The outlet 57 b of the second EGR passage 57 is connected to the first EGR passage 52 downstream from the first EGR valve 53. The second EGR valve 58 is an open / close valve that can switch between opening and closing with high responsiveness, although the opening degree cannot be adjusted, and is an electrically controlled electric valve. The second EGR passage 57 corresponds to an example of the exhaust gas recirculation passage of the present invention, and the second EGR valve 58 corresponds to an example of the exhaust gas recirculation valve of the present invention.

  As shown in FIG. 1, various sensors 41 to 46 provided in the engine 1 constitute an operation state detection unit for detecting the operation state of the engine 1. An accelerator sensor 42 is provided on the accelerator pedal 27 provided in the driver's seat. The accelerator sensor 42 detects the depression angle of the accelerator pedal 27 as the accelerator opening ACC, and outputs an electric signal corresponding to the detected value. The water temperature sensor 43 provided in the engine 1 detects the temperature (cooling water temperature) THW of the cooling water flowing through the water jacket 11a formed in the cylinder block 11 and outputs an electric signal corresponding to the detected value. A rotational speed sensor 44 provided in the engine 1 detects a rotational speed (engine rotational speed) NE of the crankshaft 3 and outputs an electrical signal corresponding to the detected value. The sensor 44 is configured to detect the rotation of the timing rotor 28 fixed to one end of the crankshaft 3 for each predetermined angle. An air flow meter 45 provided in the intake passage 4 upstream from the electronic throttle device 7 detects the intake air amount QA in the intake passage 4 and outputs an electric signal corresponding to the detected value. The oxygen sensor 46 provided in the exhaust passage 5 detects the oxygen concentration (output voltage) Ox in the exhaust led to the exhaust passage 5 and outputs an electrical signal corresponding to the detected value.

  The engine system includes an electronic control unit (ECU) 50 for controlling the operation of the engine 1. Various sensors 41 to 46 are connected to the ECU 50, respectively. Further, the ECU 50 is connected to the VVT 22, the motor 31 of the electronic throttle device 7, the port injectors 32, the in-cylinder injectors 33, the ignition coils 34, the first EGR valve 53, the second EGR valve 58, and the bypass valve 56, respectively. . The ECU 50 corresponds to an example of a control unit of the present invention.

  In this embodiment, the ECU 50 executes the VVT 22, the motor 31, each port injector 32, each of the port injectors 32 to execute fuel injection control, ignition timing control, EGR control, deceleration control, and the like based on output signals from the various sensors 41 to 46. The in-cylinder injector 33, each ignition coil 34, the first EGR valve 53, the second EGR valve 58, and the bypass valve 56 are controlled.

  Here, the fuel injection control is to control the fuel injection amount and the injection timing by each port injector 32 and in-cylinder injector 33 according to the operating state of the engine 1. The ignition timing control is to control the ignition timing by each ignition plug 33 by controlling each ignition coil 34 according to the operating state of the engine 1. The EGR control is to control the EGR flow rate returned to each combustion chamber 15 by controlling the first EGR valve 53, the second EGR valve 58, and the bypass valve 56 in accordance with the operating state of the engine 1. The deceleration control is to control various devices in order to protect the three-way catalyst 10a of the catalytic converter 10 from oxygen when the engine 1 is decelerated.

  As is well known, the ECU 50 includes a central processing unit (CPU), various memories, an external input circuit, an external output circuit, and the like. The memory stores a predetermined control program related to various controls of the engine 1. The CPU executes the various controls described above based on a predetermined control program based on the detection signals of the various sensors 41 to 46 input via the input circuit.

  Next, the processing content of the deceleration control in this embodiment will be described in detail. FIG. 3 shows the processing contents from a flowchart.

  When the process proceeds to this routine, in step 100, the ECU 50 determines whether or not there is a request for a deceleration fuel cut (deceleration F / C) for the engine 1 that is in operation. Here, the ECU 50 determines whether or not a deceleration fuel cut is requested based on the detection value of the accelerator sensor 42. The ECU 50 proceeds to step 110 when the determination result is affirmative, and proceeds to step 240 when the determination result is negative.

  In step 110, the ECU 50 takes in the engine rotation speed NE based on the detection value of the rotation speed sensor 44.

  Next, in step 120, the ECU 50 closes the first EGR valve 53. In step 130, the ECU 50 opens the second EGR valve 58. At this time, the second EGR valve 58 opens with good responsiveness from the closed state.

  Next, at step 140, the ECU 50 starts counting the elapsed time after opening the second EGR valve 58 (time after the second EGR valve opening) TFCE.

  Next, in step 150, the ECU 50 determines whether or not the throttle valve fully closed flag XTRC is “1”. As will be described later, the flag XTRC is set to “1” when the control for fully closing the throttle valve 9 is executed, and is set to “0” when the control is not executed. . The ECU 50 proceeds to step 160 when the determination result is affirmative, and jumps to step 190 when the determination result is negative.

  In step 160, the ECU 50 determines whether or not the time TFCE after the second EGR valve opening is greater than a predetermined value “A−B”. Here, “A” is the time until the EGR gas reaches the intake passage 4 (intake manifold 8) via the second EGR passage 57 after the second EGR valve 58 is opened (exhaust recirculation arrival time (EGR arrival). Time)). “B” means the time from when the throttle valve 9 is fully closed until the intake air amount QA flowing into the engine 1 decreases (intake air amount decrease time). If the determination result in step 160 is affirmative, the ECU 50 proceeds to step 170. If the determination result is negative, the ECU 50 jumps the process to step 190.

  In step 170, the ECU 50 controls the throttle valve 9 to be fully closed. That is, the ECU 50 drives the motor 31 of the electronic throttle device 8 to fully close the throttle valve 9 and shut off the flow of intake air in the intake passage 4.

  Next, in step 180, the ECU 50 sets the throttle valve fully closed flag XTRC to “1”.

  Next, in step 190 after proceeding from step 150, step 160 or step 180, the ECU 50 determines whether or not the deceleration fuel cut EGR execution flag XEFC is “0”. As will be described later, the flag XEFC is set to “1” when the control for opening the second EGR valve 58 is executed at the time of deceleration fuel cut, and is set to “0” when the control is not executed. It has become. The ECU 50 proceeds to step 200 when this determination result is affirmative, and returns the process to step 100 when this determination result is negative.

In step 200, ECU 50 obtains 180 ° C. A time T180. The ECU 50 obtains this 180 ° C. A time T180 by the following equation (1). The 180 ° C. A time T180 means the exhaust stroke time when the crank angle is 180 ° A.
T180 = 60 ÷ NE ÷ 2 Equation (1)

  Next, at step 210, the ECU 50 waits for the time TFCE after the second EGR valve opening to become greater than a predetermined value (A-T180). Here, the predetermined value (A-T180) means a result of subtracting 180 ° C. A time from the EGR arrival time.

  Then, at 220, the ECU 50 executes a port injection fuel cut of the cylinder 2 that becomes the exhaust stroke. For this purpose, the ECU 50 controls the corresponding port injector 32.

  Next, in step 230, the ECU 50 executes in-cylinder injection fuel cut for the cylinder 2 that has executed port injection fuel cut. For this purpose, the ECU 50 controls the in-cylinder injector 33 of the cylinder 2 that is in the intake stroke.

  In step 240, the ECU 50 sets the deceleration fuel cut EGR execution flag XEFC to “1”, and then returns the process to step 100.

  On the other hand, in step 250 after shifting from step 100, the ECU 50 opens the first EGR valve 53.

  Next, in step 260, the ECU 50 determines whether or not the throttle valve fully closed flag XTRC is “1”. If this determination result is affirmative, the ECU 50 proceeds to step 270, and if this determination result is negative, the ECU 50 jumps the process to step 290.

  In step 270, the ECU 50 normally controls the throttle valve 9. That is, the ECU 50 controls the opening degree of the throttle valve 9 to a normal operation by controlling the motor 31 of the electronic throttle device 8 according to the accelerator opening degree TA.

  Next, in step 280, the ECU 50 sets the throttle valve fully closed flag XTEC to “0”.

  Then, in step 290 after shifting from step 260 or step 280, the ECU 50 determines whether or not the deceleration fuel cut EGR execution flag XEFC is “1”. If this determination result is affirmative, the ECU 50 proceeds to step 300, and if this determination result is negative, the ECU 50 returns the process to step 100.

  In step 300, the ECU 50 closes the second EGR valve 58. In step 310, the ECU 50 sets the deceleration fuel cut EGR execution flag XEFC to “0”, and then returns the process to step 100.

  FIG. 4 is a time chart showing an example of changes in various parameters related to the deceleration control described above. FIG. 4 shows (a) a change in the intake air amount QA, (b) a change in the throttle opening TA, (c) a change in the fuel cut (F / C) request, and (d) an opening / closing of the first EGR valve 53. Change of valve, (e) Change of opening / closing of second EGR valve 58, (f) Change of intake system EGR gas arrival, (g) Deceleration fuel cut (deceleration F / C) execution (third cylinder # 3 From: port injection F / C) change, (h) deceleration fuel cut (deceleration F / C) execution (from third cylinder # 3: in-cylinder injection F / C) change, (i) each cylinder operating stroke Show each change. Here, (i) in the change of each cylinder operation stroke, the hatched “exhaust” cell indicates execution of “port injection”, and the hatched “intake” cell indicates “in-cylinder injection”. Means execution. Further, the “exhaust” cell marked with a black triangle means “port injection fuel cut” execution, and the “intake” cell marked with a white triangle means “cylinder injection fuel cut” execution.

  In FIG. 4, at time t1, (a) the throttle opening TA starts to decrease, and when the idle opening is reached at time t2, (c) a request for fuel cut (F / C) is entered, and (a) The intake air amount QA starts to decrease. During this time, (i) the cylinder operating strokes are the “explosion” stroke in the first cylinder # 1, the “exhaust” stroke in the second cylinder # 2, the “compression” stroke in the third cylinder # 3, and the fourth cylinder # 4. In the “intake” stroke, port injection in the “exhaust” stroke is executed in the second cylinder # 2, and in-cylinder injection in the “intake” stroke is executed in the fourth cylinder # 4. Thereafter, the first EGR valve 53 is closed and the second EGR valve 58 is controlled to open at time t3 by the advance control in which the EGR arrival time A is predicted. Next, at time t4 when the third cylinder # 3 enters the “exhaust” stroke, (g), (i) port injection fuel cut (port injection F / C) is executed, and then the other cylinders # 1, # Port injection fuel cut is also executed at 2 and # 4. Further, at time t6 when the third cylinder # 3 enters the “intake” stroke, (h), (i) in-cylinder injection fuel cut (in-cylinder injection F / C) is executed, and then the other cylinders # 1, In-cylinder injection fuel cut is also executed in # 2 and # 4. That is, as shown in FIG. 4, between time t3 and time t6, the “deceleration EGR control” for circulating the EGR gas through the second EGR passage 57 is executed by controlling the opening of the second EGR valve 58. After time t6, both “deceleration EGR control” and “deceleration fuel cut (deceleration F / C)” are executed.

  According to the control device for the engine system in this embodiment described above, when there is a deceleration fuel cut request for the engine 1, the ECU 50 controls the opening of the second EGR valve 58 and controls the electronic throttle device 7 to close. As a result, the flow of fresh air (oxygen) into the intake passage 4 downstream from the electronic throttle device 7 is blocked, and a part of the exhaust led out from the engine 1 to the exhaust passage 5 is converted into the three elements of the catalytic converter 10. Without flowing to the catalyst 10a, it flows through the second EGR passage 57 to the intake passage 4 downstream from the electronic throttle device 7 and is returned to the engine 1. Therefore, the pumping loss of the engine 1 can be reduced when the engine 1 is decelerated. At the same time, the ECU 50 controls each port injector 32 and each in-cylinder injector 33 to stop based on the EGR arrival time A in order to stop the fuel supply to the engine 1. More specifically, when there is a deceleration fuel cut request for the engine 1, the ECU 50 controls the opening of the second EGR valve 58 and then the cylinder that is in the exhaust stroke most recently before the EGR arrival time A elapses. The execution of stop control (port injection fuel cut) is started from the second port injector 32, and the port injection fuel cut is sequentially executed in the same manner when the other cylinders 2 are also in the exhaust stroke. Further, when there is a deceleration fuel cut request for the engine 1, the ECU 50 controls the opening of the second EGR valve 58, and then after the EGR arrival time A has elapsed, from the in-cylinder injector 33 of the cylinder 2 in the intake stroke most recently. The execution of stop control (cylinder injection fuel cut) is started, and the cylinder injection fuel cut is sequentially executed for the other cylinders 2 in the same manner. Accordingly, when the intake passage 4 downstream of the electronic throttle device 7 is filled with the recirculated EGR gas, the fuel supply to the engine 1 is stopped, that is, the fuel supply to the cylinder 2 that becomes the exhaust stroke is stopped. Since the fuel supply to the cylinder 2 which is stopped and becomes the intake stroke is stopped, the inflow of oxygen to the three-way catalyst 10a is suppressed thereafter. Therefore, deterioration of the three-way catalyst 10a due to oxygen can be suppressed.

  Further, according to this embodiment, when there is a deceleration fuel cut request for the engine 1, the ECU 50 controls the first EGR valve 53 to close, so that the EGR gas returns to the engine 1 only through the second EGR passage 57. Is done. For this reason, when the fuel supply to the engine 1 is stopped, the EGR gas can be recirculated relatively quickly using the second EGR passage 57 having a short path. Further, the ECU 50 controls the opening of the first EGR valve 53 as necessary during normal operation without a deceleration fuel cut request, so that during normal operation, a part of the exhaust gas that has passed through the three-way catalyst 10a is used as EGR gas. The refrigerant is returned to the engine 1 via the first EGR passage 52. For this reason, during normal operation of the engine 1, the exhaust gas purified by the three-way catalyst 10a can be recirculated to the engine 1 as EGR gas.

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

  In the following description, components equivalent to 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 the processing contents of the deceleration control. FIG. 5 is a flowchart showing the processing contents of the deceleration control in this embodiment. The flowchart of FIG. 5 differs from the flowchart of FIG. 3 in that step 400 is provided between step 230 and step 240.

  According to the flowchart of FIG. 5, the ECU 50 executes the in-cylinder injection fuel cut for the cylinder 2 that has performed the port injection fuel cut in step 230, and then the cylinder 2 that has performed the port injection fuel cut in step 400. In-cylinder injection is performed once by the in-cylinder injector 33 in the other cylinder 2 that is in the exhaust stroke at the same timing as the intake stroke. Thereafter, the ECU 50 proceeds to step 240.

  FIG. 6 is a time chart showing an example of changes in various parameters related to the deceleration control described above. FIG. 6 shows changes in (j) in-cylinder injection execution (# 4˜) in addition to (a) ˜ (i) in FIG.

  In FIG. 6, unlike FIG. 4, at time t <b> 6 when the third cylinder # 3 enters the “intake” stroke, when the (h), (i) in-cylinder injected fuel cut is executed, the “exhaust” stroke is performed. In-cylinder injection is executed once by the in-cylinder injector 33 in the “exhaust” stroke of the four cylinders # 4, and then in-cylinder injection is executed in the same manner for the other cylinders # 1, # 2, and # 3.

  According to this embodiment, the following operational effects can be obtained in addition to the operational effects of the first embodiment. That is, when the ECU 50 starts the port injection fuel cut from the port injector 32 of the cylinder 2 in the exhaust stroke, the ECU 50 injects the cylinder injector 33 in the other cylinder 2 in the exhaust stroke at the same timing as the intake stroke of the cylinder 2. Since the control is performed, the fuel is mixed with the exhaust gas led out to the exhaust passage 5. Therefore, the fuel flows to the three-way catalyst 10a as the exhaust gas flows to the three-way catalyst 10a. For this reason, it can suppress that the three-way catalyst 10a becomes lean.

<Third Embodiment>
Next, a third embodiment of the engine system control device according to the present invention will be described in detail with reference to the drawings.

  This embodiment is different in configuration from each of the above embodiments in terms of the processing content of the deceleration control. FIG. 7 is a flowchart showing the processing contents of the deceleration control in this embodiment. The flowchart in FIG. 7 is different from the flowchart in FIG. 3 in that steps 500 and 510 are provided between steps 130 and 140 and step 520 is provided between steps 280 and 290.

  According to the flowchart of FIG. 7, the ECU 50 opens the second EGR valve 58 in step 130, and then in step 500 determines the target displacement amount TVTF related to the VVT 22 at the time of deceleration fuel cut according to the engine speed NE. calculate. Here, the target displacement amount TVTF is set so as to control the VVT 22 so as to increase the valve overlap as the engine rotational speed NE is higher. The ECU 50 can obtain the target displacement amount TVTF according to the engine rotational speed NE by referring to a predetermined displacement amount map (not shown).

  Next, at step 510, the ECU 50 controls the VVT 22 to the target variable TVTF. That is, when the ECU 50 performs the opening control of the second EGR valve 58 in response to the deceleration fuel cut request for the engine 1, the ECU 50 controls the VVT 22 so as to increase the valve overlap as the engine speed NE increases. Thereafter, the ECU 50 proceeds to step 140.

  On the other hand, the ECU 50 sets the throttle valve fully closed flag XTEC to “0” in step 280 and then normally controls the VVT 22 in step 520. That is, the ECU 50 controls the valve overlap to the normal operation by controlling the VVT 22 according to the operating state of the engine 1. Thereafter, the ECU 50 proceeds to step 290.

  In this embodiment, as the second EGR valve 58, an opening / closing valve capable of switching between opening and closing with good responsiveness is used although the opening degree cannot be adjusted. Therefore, the structure of the second EGR valve 58 can be simplified to reduce the size and cost. On the other hand, with the second EGR valve 58, the EGR gas flow rate cannot be adjusted when the valve is opened.

  Here, when the maximum flow rate of the second EGR valve 58 is matched with the required flow rate in the low rotation speed region of the engine 1 (region where the engine rotation speed NE is low), the high rotation speed region of the engine 1 (the engine rotation speed NE is high). In the region), the EGR gas flow rate is insufficient. For this reason, when the electronic throttle device 7 is controlled to be fully closed in the high rotation speed range of the engine 1, the intake pressure downstream of the electronic throttle device 7 becomes a high negative pressure, that is, approaches a vacuum. As a result, oil rises in the engine 1 and the consumption of engine oil may increase. FIG. 8 is a graph showing the relationship between the intake pressure and the engine rotational speed NE when the maximum flow rate of the second EGR valve 58 is matched to the required flow rate in the low rotational speed range. FIG. 9 is a graph showing the relationship between the engine speed NE and the amount of VVT displacement in the same case. In FIG. 8, the solid line shows the case where the second EGR valve 58 is closed, and the broken line shows the case where the second EGR valve 58 is opened. It can be seen that in both cases, the higher the engine speed NE, the higher the negative pressure. In FIG. 8, in order to suppress the increase in the negative pressure of the intake pressure to a certain level of the two-dot chain line, it is necessary to increase the displacement amount of the VVT 22 as the engine rotational speed NE increases as shown by the broken line in FIG. 9. There is. In this embodiment, the target displacement amount TVTF of the VVT 22 is increased as the engine rotational speed NE is increased, so that the internal EGR can be increased and the oil increase can be suppressed.

  On the other hand, when the maximum flow rate of the second EGR valve 58 is matched with the required flow rate in the high rotation speed range of the engine 1, the EGR gas flow rate becomes excessive in the low rotation speed range of the engine 1. Therefore, when the electronic throttle device 7 is controlled to be fully closed in the high rotation speed range of the engine 1, the intake negative pressure downstream of the electronic throttle device 7 is reduced to a low negative pressure. As a result, the deceleration performance of the engine 1 may be deteriorated. FIG. 10 is a graph showing the relationship between the intake pressure and the engine rotational speed NE when the maximum flow rate of the second EGR valve 58 is matched with the required flow rate in the high rotational speed range. FIG. 11 is a graph showing the relationship between the engine speed NE and the amount of VVT displacement in the same case. In FIG. 10, the solid line indicates the case where the second EGR valve 58 is closed, and the broken line indicates the case where the second EGR valve 58 is opened. It can be seen that when the second EGR valve 58 is closed, the higher the engine speed NE, the higher the negative pressure. It can be seen that when the second EGR valve 58 is opened, the intake pressure increases as the engine speed NE decreases. On the other hand, when the second EGR valve 58 is closed, it can be seen that the intake pressure decreases as the engine speed NE increases. In FIG. 10, even if the second EGR valve 58 is opened, the intake pressure does not become so low that oil rises. Therefore, as shown in FIG. 11, the amount of displacement of the VVT 22 is controlled according to the engine speed NE. There is no need to do.

  According to this embodiment, the following operational effects can be obtained in addition to the operational effects of the first embodiment. That is, when the ECU 50 performs the opening control of the second EGR valve 58 in response to the deceleration fuel cut request for the engine 1, the ECU 50 controls the VVT 22 so as to increase the valve overlap as the engine speed NE increases. Therefore, the EGR gas flow rate that is insufficient in the high rotation speed range is compensated by the internal EGR generated in each cylinder 2 by the valve overlap. For this reason, it is possible to prevent the intake pressure from becoming a high negative pressure, and it is possible to prevent the oil from rising in the engine 1.

  The present invention is not limited to the above-described embodiments, and a part of the configuration can be appropriately changed and implemented without departing from the spirit of the invention.

  (1) In each of the above embodiments, both the pre-cylinder injector (port injector) 32 and the in-cylinder injector (in-cylinder injector) 33 are provided in the engine 1 as fuel supply means. However, the port injector and the in-cylinder injector are provided. Either of these may be provided in the engine.

  (2) In each of the above embodiments, in addition to the exhaust gas recirculation passage (second EGR passage) 57 and the exhaust gas recirculation valve (second EGR valve) 58, another exhaust gas recirculation passage (first EGR passage) 52 and another exhaust gas recirculation valve ( Although the first EGR valve) 53 is provided, only the second EGR passage and the second EGR valve may be provided.

  (3) In the third embodiment, the VVT 22 is controlled in the processing content of the deceleration control of the first embodiment. However, the VVT can also be controlled in the processing content of the deceleration control of the second embodiment.

  The present invention can be used for an engine system in which a part of exhaust gas is recirculated to the engine as EGR gas and fuel supply to the engine is stopped when there is a request for deceleration to the engine.

1 Engine 2 Cylinder 4 Intake passage 5 Exhaust passage 7 Electronic throttle device (intake air amount adjustment valve)
10a Three-way catalyst 16 Intake port 17 Exhaust port 18 Intake valve 19 Exhaust valve 22 VVT (variable valve timing mechanism)
32 port injector (fuel supply means, cylinder front injection valve)
33 In-cylinder injector (fuel supply means, in-cylinder injection valve)
50 ECU (control means)
52 1st EGR passage (another exhaust gas recirculation passage)
52a entrance (separate entrance)
52b Exit (separate exit)
53 1st EGR valve (another exhaust gas recirculation valve)
57 Second EGR passage (exhaust gas recirculation passage)
57a Inlet 57b Outlet 58 Second EGR valve (exhaust gas recirculation valve)
A EGR arrival time (exhaust gas recirculation arrival time)

Claims (6)

An intake passage for introducing intake air into the engine;
An intake air amount adjusting valve for adjusting the intake air amount in the intake passage;
An exhaust passage for leading exhaust from the engine;
A catalyst for purifying exhaust flowing in the exhaust passage;
Fuel supply means for supplying fuel to the engine;
An exhaust gas recirculation passage for flowing a part of the exhaust gas led out from the engine to the exhaust gas passage as an exhaust gas recirculation gas to the intake passage and recirculating to the engine;
The exhaust gas recirculation passage includes an inlet and an outlet, the inlet communicates with the exhaust passage upstream of the catalyst, and the outlet communicates with the intake passage downstream of the intake air amount adjustment valve;
An exhaust gas recirculation valve for opening and closing the exhaust gas recirculation passage;
In an engine system control device comprising control means for controlling the operation of the engine,
When there is a deceleration fuel cut request for the engine, the control means controls the opening of the exhaust gas recirculation valve and closes the intake air amount adjustment valve, and the exhaust gas recirculation gas passes through the exhaust gas recirculation passage. An engine system characterized in that the fuel supply means is controlled to stop based on the exhaust gas recirculation arrival time in order to stop the fuel supply to the engine when the time until the intake passage is reached is the exhaust gas recirculation arrival time. Control device. The engine is a 4-cycle reciprocating engine having a plurality of cylinders,
The fuel supply means is a plurality of cylinder front injection valves that inject fuel into the intake passage immediately before each cylinder.
The control means performs the opening control of the exhaust gas recirculation valve when there is a deceleration fuel cut request for the engine, and before the exhaust gas recirculation arrival time elapses, the cylinder of the cylinder that is in the exhaust stroke most recently 2. The engine system control device according to claim 1, wherein stop control is started from a pre-injection valve, and the cylinder pre-injection valve is sequentially controlled to stop when the other cylinders are also in the exhaust stroke. The engine is a 4-cycle reciprocating engine having a plurality of cylinders,
The fuel supply means is a plurality of in-cylinder injection valves that directly inject the fuel into the cylinders,
When there is a deceleration fuel cut request for the engine, the control means controls the opening of the exhaust gas recirculation valve, and after the exhaust gas recirculation arrival time has elapsed, the in-cylinder injection of the cylinder in the most recent intake stroke 2. The engine system control device according to claim 1, wherein stop control is started from a valve, and the in-cylinder injection valves are sequentially controlled to stop when the other cylinders are also in the intake stroke. When the control means starts the stop control from the cylinder pre-injection valve of the cylinder in the exhaust stroke, the control means controls the in-cylinder injection valve in the other cylinder that becomes the exhaust stroke at the same timing as the intake stroke of the cylinder. 4. The engine system control device according to claim 3, wherein injection control is performed. Another exhaust gas recirculation passage for flowing a part of the exhaust led out from the engine to the exhaust passage as exhaust gas recirculation gas to the intake passage and recirculating to the engine;
The another exhaust gas recirculation passage includes a separate inlet and a separate outlet, the separate inlet communicates with the exhaust passage downstream of the catalyst, and the separate outlet communicates with the intake passage downstream of the intake amount adjustment valve. And
Another exhaust recirculation valve for adjusting the flow rate of the exhaust recirculation gas in the another exhaust recirculation passage,
The control means controls to close the other exhaust gas recirculation valve when there is a deceleration fuel cut request for the engine, and if necessary, during the normal operation without the deceleration fuel cut request, the other exhaust gas recirculation valve. 2. The engine system control apparatus according to claim 1, wherein the valve opening control is performed. Each of the cylinders includes an intake port that communicates with the intake passage and an exhaust port that communicates with the exhaust passage;
The intake port is provided with an intake valve, and the exhaust port is provided with an exhaust valve. The intake valve and the exhaust valve are driven to open and close in conjunction with the operation stroke of the engine,
A variable valve timing mechanism for changing a valve overlap between the intake valve and the exhaust valve;
The control means controls the variable valve timing mechanism so as to increase the valve overlap as the engine speed increases when the exhaust gas recirculation valve is controlled to open in response to a deceleration fuel cut request for the engine. The engine system control device according to claim 2 or 3, wherein

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