JP6160816B2 - Engine control device - Google Patents

Description

  The present invention relates to an engine control device including a wastegate valve for adjusting a supercharging pressure by a supercharger such as a turbocharger.

  In recent years, in vehicles such as automobiles, the engine is automatically stopped when a predetermined automatic stop condition is satisfied, and idle stop control is executed to restart the engine that is automatically stopped when a predetermined restart condition is satisfied. Control devices have been put into practical use.

  In general, an engine equipped with a supercharger such as a turbocharger is provided with a wastegate valve for adjusting the supercharging pressure. By opening and closing the waste gate valve, an excessive increase in the supercharging pressure is suppressed, the stability of the supercharging pressure is improved, and damage to the engine and the supercharger itself is suppressed.

  And, in an engine equipped with a supercharger, when performing idle stop control, a technique is known in which the opening and closing of the wastegate valve is controlled to stop and restart the engine quickly. . For example, in some cases, the wastegate valve is fully opened during the automatic stop of the engine in the idle stop control, thereby improving the scavenging performance in the cylinder and improving the restartability after the engine is stopped. Further, for example, when there is a request for restarting the engine during the automatic stop of the engine in the idle stop control, there is one that controls the opening and closing of the wastegate valve based on whether or not the self-recovery is possible (for example, , See Patent Document 1).

International Publication No. WO2012 / 137345 Pamphlet

  By the way, the idling stop control is generally executed when the supercharging pressure of the supercharger is low and the wastegate valve is opened. On the other hand, since the intake air is throttled by the throttle valve immediately before the idling stop control is executed and the engine automatically stops, the intake manifold is likely to have a negative pressure. For this reason, during idling stop control, exhaust gas (burned gas) flows backward from the exhaust pipe due to the negative pressure, and the exhaust gas tends to remain in the cylinder (combustion chamber). That is, oxygen shortage easily occurs in the combustion chamber when the engine is restarted.

  For example, such a situation is particularly likely to occur when valve overlap is set at the opening and closing timing of the intake valve and the exhaust valve. Specifically, when the engine stops near the top dead center of the intake stroke, there is a possibility that exhaust gas flows back into the intake manifold from the exhaust port through the combustion chamber. For this reason, there is a possibility that oxygen in the intake air is insufficient at the next start, and rapid restart cannot be performed.

  Even when the valve overlap is not set in the specification, such a situation may occur due to variation due to a change in valve clearance with time or the like.

  The present invention has been made in view of such circumstances, and provides an engine control device that can restart the engine satisfactorily during idle stop control and improve fuel efficiency. With the goal.

A first aspect of the present invention that solves the above problem includes an engine having a fuel injection valve that injects fuel into a combustion chamber of the engine, and a wastegate valve that opens and closes an exhaust bypass passage that bypasses the turbine of the turbocharger. An idle stop control means for automatically stopping the engine when a predetermined automatic stop condition is satisfied, and restarting the engine under automatic stop when a predetermined restart condition is satisfied; Opening / closing control means for controlling the opening / closing operation of the wastegate valve according to the operating state of the engine, wherein the idle stop control means supplies fuel from the fuel injection valve when the automatic stop condition is satisfied. is stopped, the on-off control means, the fuel supply from the fuel injection valve by said idling stop control unit Ru is stopped, before Even after the burned gas discharged from the combustion chamber of the engine, the control apparatus for an engine, characterized in that a closed state of the waste gate valve before the rotation stop of the engine.

  According to a second aspect of the present invention, in the engine control apparatus according to the first aspect, the opening / closing control means is configured to prevent the wastegate from being supplied before the fuel supply from the fuel injection valve is stopped by the idle stop control means. The engine control device is characterized in that the valve is opened, and the valve is closed after the fuel supply is stopped.

According to a third aspect of the present invention, in the engine control apparatus according to the first or second aspect, the open / close control means is configured such that after the burned gas is discharged from the combustion chamber of the engine, the air on the intake side is the engine. In the engine control device, the waste gate valve is closed after a period of time until the air is filled at least before the turbine is sent to an exhaust pipe provided in the engine by rotation of the engine. .

  According to a fourth aspect of the present invention, there is provided an engine control device according to any one of the first to third aspects, wherein a valve overlap is set at an opening / closing timing of the intake valve and the exhaust valve. In the control unit.

  In the present invention, exhaust resistance is suppressed by opening the waste gate valve, and each cylinder (combustion chamber) can be scavenged well. Further, by closing the wastegate valve before the engine is completely stopped, the backflow of exhaust gas into the combustion chamber can be suppressed. Therefore, when the engine is restarted, a sufficient amount of oxygen is secured in the combustion chamber, so that the restartability of the engine in the idle stop control is improved.

It is a schematic diagram of an engine provided with a control device concerning one embodiment of the present invention. It is a block diagram which shows schematic structure of the control apparatus which concerns on one Embodiment of this invention. It is a flowchart which shows the control method of the wastegate valve which concerns on one Embodiment of this invention.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

  First, the overall configuration of the engine 10 according to an embodiment of the present invention will be described. As shown in FIG. 1, the engine body 11 constituting the engine 10 includes a cylinder head 12 and a cylinder block 13, and a piston 14 is accommodated in the cylinder block 13. The piston 14 is connected to the crankshaft 16 via a connecting rod 15. The piston 14, the cylinder head 12, and the cylinder block 13 form a combustion chamber 17.

  An intake port 18 is formed in the cylinder head 12, and an intake pipe (intake passage) 20 including an intake manifold 19 is connected to the intake port 18. The intake pipe 20 is provided with an intake pressure sensor (MAP sensor) 21 that detects intake pressure and an intake air temperature sensor 22 that detects the temperature of intake air. An intake valve 23 is provided in the intake port 18, and the intake port 18 is opened and closed by the intake valve 23. That is, the intake valve 23 is configured to operate in accordance with the intake cam 24a of the intake camshaft 24 that rotates in accordance with the engine rotation so as to connect / block the combustion chamber 17 and the intake port 18. Further, an exhaust port 25 is formed in the cylinder head 12, and an exhaust pipe (exhaust passage) 27 including an exhaust manifold 26 is connected in the exhaust port 25. An exhaust valve 28 is provided in the exhaust port 25, and the exhaust valve 28 operates following the exhaust cam 29 a of the exhaust camshaft 29 in the same manner as the intake valve 23 in the intake port 18, and the combustion chamber 17 and the exhaust port. It is comprised so that communication and interruption | blocking with 25 may be performed.

  The engine body 11 is provided with a fuel injection valve 30 that injects fuel into the combustion chamber 17 of each cylinder. Although not shown, fuel is supplied to the fuel injection valve 30 from a high-pressure fuel delivery pipe. The fuel supplied from the low-pressure fuel pump in the fuel tank is supplied to the high-pressure fuel delivery pipe while being pressurized to a predetermined pressure by the high-pressure fuel pump. Furthermore, a spark plug 31 is attached to the cylinder head 12 for each cylinder.

  A turbocharger 32 that is a supercharger is provided in the middle of the intake pipe 20 and the exhaust pipe 27. The turbocharger 32 includes a turbine 32a and a compressor 32b, and the turbine 32a and the compressor 32b are connected by a turbine shaft 32c. When the exhaust gas flows into the turbocharger 32, the turbine 32a is rotated by the flow of the exhaust gas, and the compressor 32b is rotated along with the rotation of the turbine 32a. Then, air (intake air) pressurized by the rotation of the compressor 32 b is sent to the intake pipe 20 and supplied to each intake port 18.

  An intercooler 33 is provided on the intake pipe 20 on the downstream side of the compressor 32 b of the turbocharger 32, and a throttle valve 34 is provided on the downstream side of the intercooler 33. Further, the upstream side and the downstream side of the exhaust pipe 27 sandwiching the turbocharger 32 are connected by an exhaust bypass passage 35. That is, the exhaust bypass passage 35 is a passage that bypasses the exhaust gas to the exhaust pipe 27 without passing through the turbine 32 a of the turbocharger 32. The exhaust bypass passage 35 is provided with a waste gate valve (WGV) 36. The waste gate valve (WGV) 36 includes a valve body 36a and an electric actuator 36b for driving the valve body 36a, and the amount of exhaust gas flowing through the exhaust bypass passage 35 can be adjusted by the opening degree of the valve body 36a. ing. The opening degree of the valve body 36a is detected by, for example, a sensor (not shown), and the supercharging pressure of the turbocharger 32 can be adjusted by adjusting the detected opening degree of the valve body 36a.

  Further, the upstream side and the downstream side of the intake pipe 20 sandwiching the turbocharger 32 are connected by an intake bypass passage 37. That is, the intake bypass passage 37 is a passage that bypasses the intake air to the intake pipe without passing through the compressor 32b of the turbocharger 32. The intake bypass passage 37 is provided with an intake bypass valve 38 that opens and closes the intake bypass passage 37. Although the configuration of the intake bypass valve 38 is not particularly limited, in the present embodiment, similarly to the waste gate valve 36, the configuration includes a valve body and an actuator.

A three-way catalyst 39, which is an exhaust gas purifying catalyst, is interposed in the exhaust pipe 27 on the downstream side of the turbine 32a of the turbocharger 32. An O ₂ sensor 40 for detecting the O ₂ concentration of the exhaust gas after passing through the catalyst is provided on the outlet side of the three-way catalyst 39, and the air-fuel ratio of the exhaust gas before passing through the catalyst is provided on the inlet side of the three-way catalyst 39. A linear air-fuel ratio sensor (LAFS) 41 for detecting (exhaust air-fuel ratio) is provided.

  The engine 10 includes an electronic control unit (ECU) 50. The ECU 50 includes an input / output device, a storage device that stores a control program, a control map, and the like, a central processing unit, timers, and counters. Yes. The ECU 50 performs overall control of the engine 10 based on information from various sensors. The engine control apparatus according to the present embodiment is configured by such an ECU 50, and, as will be described below, the opening / closing operation (opening degree) of the waste gate valve 36 according to the operating state of the engine 10 (engine body 11). To control.

  The engine control apparatus according to the present invention is characterized by controlling the opening / closing operation of the waste gate valve 36 during idle stop control. As shown in FIG. 2, the ECU 50 includes an operating state detecting means 51, Stop control means 52 and open / close control means 53 are provided.

  The driving state detection means 51 detects the driving state of the engine 10 based on information from various sensors such as the throttle position sensor 54 and the crank angle sensor 55, for example. For example, the operating region (operating state) of the engine 10 is specified by acquiring the rotational speed and load of the engine 10 based on information from various sensors and referring to a predetermined map.

  The idle stop control means 52 executes idle stop control based on the detection result of the driving state detection means 51 and the like. That is, the idle stop control means 52 automatically stops the engine 10 when a predetermined idle stop condition (automatic stop condition) is satisfied, and restarts the engine 10 under automatic stop when a predetermined restart condition is satisfied. . For example, in this embodiment, the idle stop control means 52 controls the fuel injection valve 30 to stop the fuel supply into the combustion chamber 17 when the idle stop condition is satisfied, and within the combustion chamber 17 when the restart condition is satisfied. The fuel supply to is resumed and cranking is started.

  The opening / closing control means 53 controls the opening / closing operation of the waste gate valve 36 according to the detection result of the operation state detecting means 51. During normal operation where the idle stop condition is not satisfied, the opening / closing control means 53 appropriately controls the opening / closing operation of the waste gate valve 36 according to the operating state of the engine 10 detected by the operating state detecting means 51. On the other hand, when the idle stop condition is satisfied, that is, when the idle stop control is executed by the idle stop control means 52, the open / close control means 53 opens and closes the waste gate valve 36 according to the operating state of the fuel injection valve 30. Control the behavior. Specifically, the open / close control means 53 is configured so that the waste gate valve 36 is closed after a predetermined period after the fuel supply from the fuel injection valve 30 is stopped by the idle stop control means 52. To control.

  Here, the operating region (operating state) of the engine 10 in which the idle stop control is executed is generally a low rotation and low load region, and the waste gate valve 36 is in the open state. In this case, at a predetermined timing after the fuel supply from the fuel injection valve 30 is stopped by the idle stop control means 52, the open / close control means 53 closes the waste gate valve 36 in the open state ( The valve is closed).

  The predetermined timing (predetermined period) is that the air on the intake side is not combusted by the rotation after the fuel stops but is sent to the exhaust pipe 27 until the air is filled at least in the range before the turbine 32a or downstream of the turbine 32a It is a period. This period depends on the volume between the exhaust port 25 and the turbine 32a and the volume between the intake port 18 and the throttle valve 34. That is, as the volume between the exhaust port 25 and the turbine 32a is smaller than the volume between the intake port 18 and the throttle valve 34, the period becomes shorter. For example, by incorporating the exhaust port 25 to the exhaust manifold 26 in the cylinder head 12, the volume between the exhaust port 25 and the turbine 32a can be suppressed. Therefore, the period can be set shorter than that of an engine equipped with a separate exhaust manifold 26. Thereby, for example, the wastegate valve 36 can be closed before the engine 10 stops.

  On the other hand, if the waste gate valve 36 is in the closed state when the idle stop condition is satisfied, the idle stop control means is provided after the waste gate valve 36 is once opened (after being held in the open state). When the fuel supply from the fuel injection valve 30 is stopped by 52, the open / close control means 53 closes the wastegate again (to bring the valve into a closed state).

  In this way, when the fuel supply from the fuel injection valve 30 is stopped by the idle stop control means 52 regardless of whether the wastegate valve 36 is in an open state or a closed state, the open / close control means 53 The open / close state of the waste gate valve 36 is appropriately controlled so that the waste gate valve 36 enters the closed state after the open state. Alternatively, one of the idle stop start conditions is to control the wastegate valve 36 to be closed after the fuel supply is stopped, including that the WGV valve is open.

  Further, when the idle stop control is executed, the restartability of the engine 10 is improved by closing the wastegate valve 36 after a predetermined period has elapsed since the fuel supply from the fuel injection valve 30 was stopped. Can do. Specifically, by opening the waste gate valve 36, the exhaust resistance is suppressed, and the inside of each combustion chamber 17 can be scavenged well. In particular, by closing the wastegate valve 36 after a predetermined period has elapsed since the fuel supply from the fuel injection valve 30 was stopped and before the engine was completely stopped, the combustion chamber 17 after scavenging, The backflow of the exhaust gas into the intake port 18 and the intake manifold 19 can be suppressed. For example, even if the continuously variable valve timing device included in the engine 10 is in a state where the valve overlap is set, exhaust gas passes through the turbine and exhaust resistance increases by closing the wastegate valve 36. In addition, the backflow of exhaust gas is suppressed.

  As a result, when the engine 10 is restarted, a sufficient amount of oxygen is secured in the combustion chamber 17, the intake port 18, and the intake manifold 19. Therefore, the restartability of the engine 10 in the idle stop control can be improved. Further, if the air sent to the exhaust pipe 27 by the rotation after the fuel stops is filled up to the front of the turbine 32a, a sufficient amount of oxygen is secured on the intake side in the same manner even if a reverse flow occurs.

  Here, an example of the control of the opening / closing operation of the waste gate valve will be described with reference to the flowchart of FIG.

  As shown in FIG. 3, during normal operation, the opening / closing control means 53 appropriately controls the opening / closing operation of the waste gate valve (WGV) 36 according to the detection result of the operation state detection means 51, that is, according to the operation state of the engine 10. Control (step S1). During such normal operation, the idle stop control means 52 determines whether or not the idle stop condition is satisfied based on the detection result of the operating state detection means 51 (step S2).

  Here, when it is determined that the idle stop condition is not satisfied (step S2: No), this control is terminated. On the other hand, if it is determined in step S2 that the idle stop condition is satisfied (step S2: Yes), the process proceeds to step S3, and the opening / closing control means 53 opens the wastegate valve 36. If the wastegate valve 36 is in the open state when the idle stop condition is satisfied, the open state is maintained as it is. After that, the idle stop control means 52 stops the fuel supply from the fuel injection valve 30 into the combustion chamber 17 (step S4), and the open / close control means 53 closes the waste gate valve 36 in step S5. Thereby, control of the opening / closing operation | movement of the waste gate valve 36 at the time of the automatic stop of the engine 10 by idle stop control is complete | finished.

  As described above, in the engine control apparatus according to the present embodiment, when the fuel supply from the fuel injection valve 30 is stopped by the idle stop control means 52, the waste gate valve 36 is brought into the valve closing state through the valve opening state. In addition, the open / close control means 53 appropriately controls the open / close state of the waste gate valve 36. That is, the waste gate valve 36 is opened before stopping the fuel supply.

  Thereby, the driving load of the turbine 32a can be reduced and fuel consumption can be reduced. At this time, the positive load between the exhaust port 25 and the turbine 32a of the turbocharger 32 is reduced by reducing the driving load of the turbine 32a. Therefore, by stopping the fuel supply with the waste gate valve 36 opened, the burned gas is discharged well from the combustion chamber 17. Thereafter, by closing the waste gate valve 36, the backflow of exhaust gas into the combustion chamber 17, the intake port 18, and the intake manifold 19 after scavenging can be suppressed. As a result, when the restart condition is satisfied, the engine 10 can be restarted quickly.

  Further, by closing the wastegate valve 36, the movement of the exhaust gas in the exhaust system including the exhaust manifold and the exhaust pipe is restricted. For this reason, the catalyst temperature is also easily maintained, and the engine 10 can be restarted satisfactorily even when the idle stop control is executed for a relatively long time.

  As mentioned above, although embodiment of this invention was described, of course, this invention is not limited to the above-mentioned embodiment.

  For example, in the above-described embodiment, a direct injection type engine that injects fuel into the combustion chamber (cylinder) is illustrated. However, the present invention includes an intake pipe injection type engine that injects fuel into the intake pipe, for example, It can also be applied to other types of engines. Moreover, although only the engine was illustrated in the above-mentioned embodiment, this invention is naturally applicable to the engine of the hybrid vehicle provided with an electric motor, for example.

DESCRIPTION OF SYMBOLS 10 Engine 11 Engine main body 12 Cylinder head 13 Cylinder block 14 Piston 15 Connecting rod 16 Crankshaft 17 Combustion chamber 18 Intake port 19 Intake manifold 20 Intake pipe 21 Intake pressure sensor 22 Intake temperature sensor 23 Intake valve 24 Intake camshaft 24a Intake cam 25 Exhaust Port 26 Exhaust manifold 27 Exhaust pipe 28 Exhaust valve 29 Exhaust cam shaft 29a Exhaust cam 30 Fuel injection valve 31 Spark plug 32 Turbocharger (supercharger)
32a Turbine 32b Compressor 32c Turbine shaft 33 Intercooler 34 Throttle valve 35 Exhaust bypass passage 36 Wastegate valve 37 Intake bypass passage 38 Intake bypass valve 39 Three-way catalyst 40 O ₂ sensor 41 LAFS
50 ECU
54 Throttle position sensor 55 Crank angle sensor

Claims (4)

A fuel injection valve for injecting fuel into the combustion chamber of the engine;
A wastegate valve that opens and closes an exhaust bypass passage that bypasses the turbocharger turbine;
An engine control device comprising:
Idle stop control means for automatically stopping the engine when a predetermined automatic stop condition is satisfied, and restarting the engine under automatic stop when a predetermined restart condition is satisfied;
Opening and closing control means for controlling the opening and closing operation of the wastegate valve according to the operating state of the engine,
The idle stop control means stops the fuel supply from the fuel injection valve when the automatic stop condition is satisfied,
Said switching control means, wherein when the fuel supply from the fuel injection valve by an idle stop control means Ru is stopped, the even after the burned gas discharged from the combustion chamber of the engine, before the rotation stop of the engine An engine control device characterized in that the waste gate valve is closed . The engine control device according to claim 1,
The open / close control means opens the waste gate valve before the fuel supply from the fuel injection valve is stopped by the idle stop control means, and closes the fuel supply after the fuel supply stops. The engine control device. The engine control device according to claim 1 or 2,
After the burned gas is discharged from the combustion chamber of the engine, the opening / closing control means sends air on the intake side to an exhaust pipe provided in the engine by rotation of the engine, and this air is filled at least before the turbine. An engine control device characterized in that the waste gate valve is closed after the elapse of a period until it is released . The engine control apparatus according to any one of claims 1 to 3,
An engine control device characterized in that valve overlap is set at the opening and closing timing of the intake valve and the exhaust valve.

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