Vehicle control device

Abstract

To provide a control device for a vehicle, which suppresses the generation of condensed water in a cylinder while suppressing the deterioration of emissions when an engine is restarted.SOLUTION: A vehicle is equipped with an engine having a throttle valve and an EGR valve, and a transmission connected to the engine. A control device for the vehicle comprises: an intermittent operation control unit that automatically stops and restarts the engine; a determination unit that determines whether or not the shift position of the transmission is in a D range when there is a request to automatically stop the engine; and a stop control unit that, when the determination unit makes negative determination, closes the EGR valve and opens the throttle valve to scavenge burnt gas in a cylinder of the engine and stop the engine and, when the determination unit makes positive determination, opens the EGR valve to stop the engine while leaving burnt gas in the cylinder.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a vehicle control device. [Background technology]

[0002] When an engine is stopped for a long period of time, condensed water may form due to the burned gas remaining in the cylinder, which may cause problems. For this reason, a technique is known for scavenging burned gas from the cylinder when the engine is stopped (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2020-190228 Summary of the Invention [Problem to be solved by the invention]

[0004] Even in intermittent operation in which the engine is repeatedly stopped and restarted automatically, if burned gas is scavenged from inside the cylinders during automatic stopping, emissions may worsen when the engine is restarted.

[0005] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a vehicle control device that suppresses the generation of condensed water in the cylinders and also suppresses the deterioration of emissions when the engine is restarted. [Means for solving the problem]

[0006] The above object can be achieved by a vehicle control device that includes an engine having a throttle valve and an EGR valve, and a transmission connected to the engine, the vehicle control device including: an intermittent operation control unit that automatically stops and restarts the engine; a judgment unit that, when there is a request to automatically stop the engine, judges whether the shift position of the transmission is in D range; and, when the judgment unit makes a negative judgment, closes the EGR valve and opens the throttle valve to scavenge burned gases in the cylinders of the engine and stop the engine, and, when the judgment unit makes a positive judgment, opens the EGR valve to stop the engine while leaving burned gases in the cylinders.

[0007] When the shift position is switched to a position other than D range during automatic stop of the engine after a positive determination by the determination unit, the intermittent operation control unit may restart the engine.

[0008] The vehicle may include a motor that motors the engine, and a scavenging control unit that, when the ignition is turned off during automatic stop of the engine after a positive determination is made by the determination unit, closes the EGR valve, opens the throttle valve, and motors the engine using the motor to scavenge burned gases in the cylinders. [Effects of the Invention]

[0009] A vehicle control device can be provided that suppresses the generation of condensed water in the cylinders and also suppresses the deterioration of emissions when the engine is restarted. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic diagram of a hybrid vehicle. [Figure 2] FIG. 1 is a schematic configuration diagram of an engine. [Figure 3] 3 is a flowchart illustrating an example of intermittent engine operation control. DETAILED DESCRIPTION OF THE INVENTION

[0011] [Hybrid vehicle configuration] 1 is a diagram illustrating a hybrid vehicle 1 according to a first embodiment. The hybrid vehicle 1 includes an engine 10, a transmission 62, a motor generator (MG) 64, batteries 66 and 68, a direct current (DC) converter 70, accessories 72, a starter 74, and an electronic control unit (ECU) 100.

[0012] The engine 10 is a diesel engine, but may be a gasoline engine. The power of the engine 10 is transmitted to drive wheels (not shown) through a transmission 62. The hybrid vehicle 1 runs on the power generated by the engine 10.

[0013] The MG 64 functions as both an electric motor and a generator. When drive power is supplied to the MG 64, the MG 64 outputs torque, and when torque is applied to the MG 64, the MG 64 generates regenerative power. The MG 64 is, for example, an AC rotating electric machine. The AC rotating electric machine is, for example, a permanent magnet synchronous motor having a rotor with a permanent magnet embedded therein.

[0014] A pulley 61 is attached to the crankshaft of the engine 10. A pulley 65 is attached to the rotor of the MG 64. A belt 63 is stretched between the pulley 61 and the pulley 65. When the engine 10 rotates, power is transmitted to the MG 64 through the pulley 61, the belt 63, and the pulley 65. The MG 64 rotates and generates electricity.

[0015] The batteries 66 and 68 are secondary batteries that can be discharged and charged. The battery 66 has a higher voltage than the battery 68. The MG 64 is electrically connected to the battery 66 and the DC-DC converter 70 via a PCU (Power Control Unit) 67.

[0016] The PCU 67 includes an inverter. The PCU 67 converts AC power generated by the MG 64 into DC power. The battery 66 is charged with the power generated by the MG 64. The DC-DC converter 70 reduces the voltage of the power generated by the MG 64 and supplies it to the battery 68, the accessories 72, and the starter 74. The starter 74 starts the engine 10. The battery 68 is charged with the power supplied from the MG 64. The accessories 72 include lights, an air conditioner, etc. The accessories 72 are driven by the power supplied from the MG 64.

[0017] The ECU 100 is a control device for the hybrid vehicle 1, and includes an arithmetic unit such as a CPU (Central Processing Unit), and storage devices such as a RAM (Random Access Memory) and a ROM (Read Only Memory). The ECU 100 performs various controls by executing programs stored in the ROM and storage device. The ECU 100 is an example of a control device for the hybrid vehicle 1, and functionally realizes a control device, an intermittent operation control unit, a determination unit, a stop control unit, and a scavenging control unit, which will be described in detail later.

[0018] The ECU 100 is electrically connected to an ignition switch 18 and a shift position sensor 19. The ignition switch 18 detects whether the ignition is on or off. The shift position sensor 19 detects whether the shift position is in P (parking) range, R (reverse) range, N (neutral) range, or D (drive) range.

[0019] The ECU 100 executes intermittent operation control that repeatedly stops and restarts the engine 10 automatically. Specifically, the ECU 100 stops the idling of the engine 10 when the vehicle speed drops to, for example, 0 km / h. The ECU 100 also restarts the engine 10 when the brake pedal is released or the accelerator pedal is operated. In other words, the ECU 100 executes so-called idling stop control. The above control is an example of control executed by the intermittent operation control unit.

[0020] [Engine outline] 2 is a schematic diagram of engine 10. Engine 10 has multiple cylinders 22. Pistons 24 are housed in each cylinder 22. The combustion of an air-fuel mixture in a combustion chamber 23 causes pistons 24 to reciprocate. The reciprocating motion of pistons 24 is converted into the rotational motion of a crankshaft.

[0021] An intake valve 42 that opens and closes the intake port 11i and an exhaust valve 44 that opens and closes the exhaust port 30e are provided in the cylinder 22. An injector 27 that injects fuel into the combustion chamber 23 is provided in the cylinder 22.

[0022] An intake pipe 11 is connected to an intake port 11i of the cylinder 22. In the intake pipe 11, an air flow meter 15 for detecting the amount of intake air and an electronically controlled throttle valve 13 are provided, in this order from the upstream side. An exhaust pipe 30 is connected to an exhaust port 30e of the cylinder 22. A catalyst 31 is provided in the exhaust pipe 30.

[0023] The engine 10 is provided with an EGR (Exhaust Gas Recirculation) device 50. The EGR device 50 includes an EGR pipe 51 and an EGR valve 52. The EGR pipe 51 connects the exhaust pipe 30 and the intake pipe 11. The EGR valve 52 is provided on the EGR pipe 51 and opens and closes the EGR pipe 51. When the EGR valve 52 opens, a portion of the burned gas is introduced into the cylinder 22 via the EGR pipe 51 and the intake pipe 11. When the EGR valve 52 closes, the communication between the exhaust pipe 30 and the intake pipe 11 is blocked, and the recirculation of the burned gas to the intake pipe 11 is stopped.

[0024] Furthermore, the ECU 100 executes a scavenging process to scavenge burned gas from inside the cylinder 22 when the engine 10 is stopped. Specifically, the ECU 100 closes the EGR valve 52 and opens the throttle valve 13 while the engine 10 is coasting with fuel injection stopped. This allows only fresh air to be introduced into the cylinder 22, scavenging burned gas from inside the cylinder 22. This prevents the temperature inside the cylinder 22 from dropping after the engine 10 is stopped, preventing condensation from occurring inside the cylinder 22. This prevents corrosion of the injector due to condensation, for example. However, in this embodiment, when the shift position is in the D range, as described below, the engine 10 is stopped without executing the scavenging process.

[0025] [Intermittent operation control] FIG. 3 is a flowchart illustrating intermittent operation control of engine 10. ECU 100 determines whether there is a request to automatically stop engine 10 (step S1). If the answer is No in step S1, this control ends. If the answer is Yes in step S1, ECU 100 determines whether the shift position is in D range (step S2). Step S2 is an example of control executed by the determination unit. If the answer is No in step S2, that is, if the shift position is other than D range, it is considered that there is a high possibility that the ignition will be turned off thereafter. Therefore, in this case, ECU 100 executes scavenging processing to stop engine 10 (step S3). Step S3 is an example of control executed by the stop control unit.

[0026] Next, the ECU 100 determines whether or not there is a request to restart the engine 10 (step S4). If the result of step S4 is No, the ECU 100 determines whether or not the ignition has been turned off (step S5). If the result of step S5 is Yes, the ECU 100 turns off the power supply to the hybrid vehicle 1 (step S13). Since the scavenging process is performed in step S3 in this way, it is possible to prevent condensed water from being generated in the cylinder 22 after the ignition is turned off. If the result of step S5 is No, the ECU 100 executes step S4 again. If the result of step S4 is Yes, the ECU 100 restarts the engine 10 (step S6).

[0027] If the answer to step S2 is Yes, that is, if the shift position is in the D range, it is determined that there is a high possibility that a restart of the engine 10 will be required later. Therefore, in this case, the ECU 100 stops the engine 10 without executing scavenging processing (step S7). Specifically, the ECU 100 keeps the EGR valve 52 open while the engine 10 is coasting with fuel injection stopped. This causes burned gas to remain in the cylinder 22 when the engine 10 is stopped. The throttle valve 13 may be open or closed.

[0028] In this way, when there is a high possibility that the engine 10 will restart, burned gas is allowed to remain in the cylinder 22. If burned gas remains in the cylinder 22, the specific heat ratio of the combustion gas at the time of restart is improved, and combustion becomes slower. As a result, the maximum temperature of the combustion gas is suppressed, the generation of NOx is suppressed, and the deterioration of emissions is suppressed. Step S7 is an example of control executed by the stop control unit.

[0029] Next, the ECU 100 determines whether or not there is a request to restart the engine 10 (step S8). If the answer is No in step S8, the ECU 100 determines whether or not the shift position has been switched from the D range to a range other than the D range (step S9). If the answer is Yes in step S8 or S9, the ECU 100 restarts the engine 10 (step S10). Here, if the answer is Yes in step S9, there is a risk that the range will be switched from the D range to the P range and the ignition will be turned off. In such a case, restarting the engine 10 can prevent the ignition from being turned off without executing the scavenging process. Step S10 is an example of control executed by the intermittent operation control unit.

[0030] If the result of step S9 is No, the ECU 100 determines whether the ignition is turned off (step S11). If the result of step S11 is No, step S8 is executed again. If the result of step S11 is Yes, the ECU 100 motors the engine 10 using the MG 64 to scavenge burned gases in the cylinders 22 (step S12). Specifically, the ECU 100 closes the EGR valve 52 and opens the throttle valve 13 to motor the engine 10. This allows fresh air to be introduced into the cylinders 22 and burned gases to be discharged from the cylinders 22. Next, the ECU 100 turns off the power to the hybrid vehicle 1 (step S13).

[0031] In this way, when the ignition is turned off while the scavenging process is not being performed, scavenging is performed by motoring. This makes it possible to suppress the generation of condensed water in the cylinder 22 after the ignition is turned off. Step S12 is an example of control performed by the scavenging control unit.

[0032] In the above embodiment, the engine 10 is a diesel engine, but it may also be a gasoline engine. For example, in the case of a gasoline engine, stopping the engine without performing scavenging can prevent the air-fuel ratio around the catalyst from becoming excessively lean when the engine is restarted. This can prevent emissions from worsening.

[0033] In the above embodiment, the hybrid vehicle 1 is described as an example, but the vehicle may be an engine vehicle equipped with only an engine as a driving power source. In an engine vehicle, motoring of the engine can be performed by a starter in step S12.

[0034] Although the embodiments of the present invention have been described in detail above, the present invention is not limited to such specific embodiments, and various modifications and variations are possible within the scope of the gist of the present invention as defined in the claims. [Explanation of symbols]

[0035] 1 Hybrid vehicle 10 Engine 64 MG (motor) 100 ECU (control unit, intermittent operation control unit, judgment unit, stop control unit, scavenging control unit)

Claims

1. A control device for a vehicle including an engine having a throttle valve and an EGR valve, and a transmission connected to the engine, an intermittent operation control unit that automatically stops and restarts the engine; a determination unit that determines whether the shift position of the transmission is in a D range when an automatic stop request for the engine is received; a stop control unit that, when the determination unit makes a negative determination, closes the EGR valve and opens the throttle valve to scavenge burned gases in the cylinders of the engine and stop the engine, and, when the determination unit makes a positive determination, opens the EGR valve to leave burned gases in the cylinders and stop the engine.

2. The vehicle control device according to claim 1 , wherein the intermittent operation control unit restarts the engine when the shift position is switched to a position other than D range during automatic engine stop after a positive determination by the determination unit.

3. the vehicle includes a motor that motors the engine; 3. The vehicle control device according to claim 2, further comprising a scavenging control unit that, when an ignition is turned off during automatic stop of the engine after a positive determination is made by the determination unit, closes the EGR valve, opens the throttle valve, and motors the engine with the motor to scavenge burned gases in the cylinders.

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