Vehicle control device

Abstract

To provide a vehicle control device which suppresses degradation of exhaust emissions.SOLUTION: A control device of a vehicle which is provided with an engine and a filter to collect ash and soot discharged from the engine comprises: a determination section which determines whether a travel distance of a vehicle with an engine in operation, which correlates with an ash accumulation amount on the filter is less than a first threshold and whether a soot accumulation amount on the filter calculated based on an engine operation state is less than a second threshold; and an execution section which executes suppression control to reduce a soot discharge from the engine when the determination section makes an affirmative determination as compared to when the determination section makes a negative determination. The first threshold is set to the travel distance corresponding to the ash accumulation amount at which ash accumulated on the filter may fail to restrict the passage of soot through the filter. The second threshold is set to the soot accumulation amount at which soot accumulated on the filter may fail to restrict the passage of soot through the filter.SELECTED DRAWING: Figure 4

Description

Technical Field

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

Background Art

[0002] Vehicles having an engine and a filter for collecting ash and soot discharged from the engine are known (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In such a filter, the deposition amount of soot and ash gradually increases as the usage time becomes longer. However, when the deposition amount in the filter is small, there is a risk that fine soot with a small particle size passes through the mesh of the filter and exhaust emissions deteriorate.

[0005] Therefore, an object of the present invention is to provide a control device for a vehicle that suppresses deterioration of exhaust emissions.

Means for Solving the Problems

[0006] The above object is achieved by a control device for a vehicle having an engine and a filter that collects ash and soot discharged from the engine, the control device including: a determination unit that determines whether or not a travel distance of the vehicle during driving of the engine, which correlates with an ash accumulation amount in the filter, is less than a first threshold value and whether or not a soot accumulation amount in the filter calculated based on an operating state of the engine is less than a second threshold value; and an execution unit that, when an affirmative determination is made by the determination unit, executes suppression control for suppressing a soot discharge amount with respect to the engine, the suppression control being executed more than when a negative determination is made by the determination unit. The first threshold value is set to a travel distance corresponding to an ash accumulation amount at which there is a possibility that soot cannot pass through the filter due to the ash accumulated in the filter, and the second threshold value is set to a soot accumulation amount at which there is a possibility that soot cannot pass through the filter due to the soot accumulated in the filter.

[0007] The suppression control may include control for bringing an injection timing of an in-cylinder injection valve of the engine closer to a timing of bottom dead center of an intake stroke than when the suppression control is not executed.

[0008] The suppression control may include control for stopping an intermittent operation in which the engine is automatically stopped and restarted.

Advantages of the Invention

[0009] It is possible to provide a control device for a vehicle that suppresses deterioration of exhaust emissions.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Best Mode for Carrying Out the Invention

[0011] [Schematic Configuration of Hybrid Vehicle] Figure 1 is a schematic configuration diagram of a hybrid vehicle 1. In the hybrid vehicle 1, a clutch 30, a motor 40, and a transmission 50 are provided in sequence in the power transmission path from the engine 10 to the drive wheels 70. The engine 10 and the motor 40 are mounted as driving sources for the running of the hybrid vehicle 1. The engine 10 is, for example, a gasoline engine, but it may also be a diesel engine. The transmission 50 and the left and right drive wheels 70 are connected via a differential gear 60. The transmission 50 includes a torque converter and an automatic transmission.

[0012] The clutch 30 is provided between the engine 10 and the motor 40 on the same power transmission path. The clutch 30 receives hydraulic pressure from the released state and becomes engaged to connect the power transmission between the engine 10 and the motor 40. The clutch 30 becomes disengaged in response to the stop of hydraulic pressure supply to cut off the power transmission between the engine 10 and the motor 40.

[0013] The motor 40 is connected to the battery 90 via the PCU 80. The motor 40 functions as a running power source of the hybrid vehicle 1 in response to power supply from the battery 90. Further, the motor 40 also functions as a generator that charges the battery 90 in response to power transmission from the engine 10 or the drive wheels 70.

[0014] The PCU 80 is controlled by the ECU 100 described later. In the case of power running operation where the motor 40 outputs torque, the PCU 80 converts the DC voltage of the battery 90 into an AC voltage and adjusts the power supplied to the motor 40. In the case of regenerative operation where the motor 40 generates electricity, the PCU 80 converts the AC voltage from the motor 40 into a DC voltage and adjusts the regenerative power supplied to the battery 90.

[0015] The hybrid vehicle 1 is provided with an ECU (Electronic Control Unit) 100 as a control device for the vehicle. The ECU 100 is an electronic control unit including an arithmetic processing circuit that performs various arithmetic processes related to the running control of the vehicle, and a memory in which control programs and data are stored. The ECU 100 is an example of a control device for the vehicle, and specifically, functionally realizes a determination unit and an execution unit, which will be described later in detail.

[0016] The ECU 100 runs the hybrid vehicle in either a motor running mode or a hybrid running mode. In the motor running mode, the ECU 100 stops the engine 10, disengages the clutch 30, and runs by the power of the motor 40. In the hybrid running mode, the clutch 30 is engaged and the vehicle runs at least by the power of the engine 10. Also, in the hybrid running mode, the output of the motor 40 can assist in driving the engine 10.

[0017] The ECU 100 executes idling stop control when a predetermined condition is satisfied. For example, when the hybrid vehicle 1 stops during signal waiting or the like while running in the hybrid running mode, the ECU 100 stops the engine 10 and disengages the clutch 30. When the depression of the brake pedal is released or the accelerator pedal is depressed during idling stop, the ECU 100 engages the clutch 30 and restarts the engine 10 by cranking with the motor 40. The idling stop control is an example of intermittent operation control.

[0018] [Schematic Configuration of Engine] FIG. 2 is a schematic configuration diagram of the engine 10. The engine 10 includes an engine body 11, an intake passage 20, and an exhaust passage 24. The engine body 11 is a multi-cylinder engine having a plurality of cylinders. An in-cylinder injection valve 12 and a spark plug 14 are provided in the engine body 11. The in-cylinder injection valve 12 directly injects fuel into the combustion chamber of the engine 10. Note that, instead of the in-cylinder injection valve 12 or in addition to the in-cylinder injection valve, a port injection valve may be provided. The spark plug 14 ignites the air-fuel mixture. A throttle valve 22 is provided in the intake passage 20. The throttle valve 22 is driven by, for example, an actuator (not shown) to adjust the intake air amount.

[0019] A three-way catalyst 26 and a GPF (Gasoline Particulate Filter) 27 are provided in the exhaust passage 24. The three-way catalyst 26 contains a catalytic metal, has an oxygen storage capacity, and purifies NOx, HC, and CO. The GPF 27 is a porous ceramic structure that collects ash and soot discharged from the engine body 11. The ash is a metal oxide contained in engine oil, fuel additives, etc. and is a non-combustible substance. The soot is generated by the evaporation of the fuel adhering to the top surface of the piston before being exposed to the flame and burned, and burns at a predetermined temperature or higher. The GPF 27 is an example of a filter. Note that, for example, when the engine 10 is a diesel engine, a DPF (Diesel Particulate Filter) is provided instead of the GPF 27.

[0020] Here, the relationship between the soot collection rate in the GPF27 and the driving distance of the hybrid vehicle 1 will be described. FIG. 3 is a graph showing the relationship between the soot collection rate in the GPF27 and the driving distance of the hybrid vehicle 1. The driving distance of the hybrid vehicle 1 here is the driving distance during the operation of the engine 10 and does not include the driving distance in the motor driving mode. FIG. 3 shows the case where the soot deposition amount in the GPF27 is a certain value other than 0 and the case where it is 0. When the soot deposition amount is constant, as the driving distance increases until it reaches a predetermined value, the soot collection rate increases, and when the driving distance is equal to or greater than the predetermined value, the soot collection rate is maintained at a high constant value. On the other hand, when the soot deposition amount is 0, the GPF27 is maintained in a low collection rate state with a low soot collection rate. This is presumably because when the soot deposition amount in the GPF27 is 0, it is easy for soot with a small particle size to pass through the mesh of the GPF27.

[0021] Also, as shown in FIG. 3, when the soot deposition amount is constant, the longer the driving distance until it reaches a predetermined value, the higher the soot collection rate. When the soot deposition amount is 0, the soot collection rate gradually increases as the driving distance increases. This is presumably because as the driving distance increases, the amount of ash deposited on the mesh of the GPF27 increases, making it difficult for soot to pass through the mesh of the GPF27.

[0022] As described above, when the driving distance is short and the soot deposition amount in the GPF27 is small, the GPF27 is in a low collection rate state with a low soot collection rate, and there is a possibility that the exhaust emissions deteriorate. Therefore, as will be described below, when the GPF27 is in a low collection rate state, the ECU 100 executes suppression control to suppress the amount of soot discharged from the engine 10.

[0023] [Suppression Control] FIG. 4 is a flowchart illustrating suppression control. The ECU 100 determines whether the engine 10 is being driven (step S1). For example, when the driving mode is the motor driving mode, the determination at step S1 is No. For example, when the driving mode is the hybrid driving mode and the idling stop as described above is not being executed, the determination at step S1 is Yes. Even when the driving mode is the hybrid driving mode, if the engine 10 is stopped due to the idling stop function, the determination at step S1 is No. If the determination at step S1 is No, this control ends.

[0024] If the determination at step S1 is Yes, the ECU 100 determines whether the driving distance of the hybrid vehicle 1 while the engine 10 is being driven is less than a first threshold value (step S2). As described above, the longer the driving distance of the hybrid vehicle 1 while the engine 10 is being driven, the larger the amount of ash deposition in the GPF 27. Therefore, the driving distance of the hybrid vehicle 1 while the engine 10 is being driven correlates with the amount of ash deposition in the GPF 27. The first threshold value is set to the driving distance corresponding to the amount of ash deposition at which there is a possibility that the passage of soot through the GPF 27 cannot be restricted by the ash deposited in the GPF 27. This is because when the amount of ash deposition is large, soot can be collected by the GPF 27 due to the deposited ash. For example, the first threshold value is set to the driving distance corresponding to the amount of ash deposition at which there is a possibility that soot will pass through the GPF 27 when the amount of soot deposition in the GPF 27 is 0. The driving distance while the engine 10 is being driven is calculated by the ECU 100 based on the vehicle speed while the engine 10 is being driven. If the determination at step S2 is No, this control ends. Step S2 is an example of the process executed by the determination unit.

[0025] If the answer is Yes in step S2, the ECU 100 determines whether the amount of soot deposition in the GPF 27 is less than the second threshold value (step S3). The second threshold value is set to an amount of soot deposition at which there is a risk that the passage of soot through the GPF 27 cannot be restricted by the soot deposited in the GPF 27. This is because when the amount of soot deposition is large, the GPF 27 can collect the soot due to the deposited soot. For example, the second threshold value is set to an amount of soot deposition at which there is a risk that the soot will pass through the GPF 27 when the amount of ash deposition in the GPF 27 is 0. The amount of soot deposition is calculated by the ECU 100 by integrating the amount of soot deposition in the GPF 27 per unit time based on the operating state of the engine 10 and the temperature of the cooling water of the engine 10. Here, when the regeneration control of the GPF 27 or fuel cut is executed in a high-temperature state of the GPF 27, the soot deposited in the GPF 27 burns. Therefore, in such a state, the ECU 100 subtracts the amount of soot deposition. The calculation of the amount of soot deposition is not limited to the above method, and other known methods may also be used. If the answer is No in step 3, this control ends. Step S3 is an example of the process executed by the determination unit.

[0026] If the answer is Yes in step S3, the ECU 100 determines that the GPF 27 is in a low collection rate state with a low soot collection rate (step S4), and executes suppression control to suppress the soot discharge amount on the engine 10 (step S5). Thus, since the suppression control is executed when the answer is Yes in steps S1 to S3, the deterioration of the exhaust emission is suppressed. Step S5 is an example of the process executed by the execution unit.

[0027] For example, the above-described suppression control is a control that makes the injection timing of the in-cylinder injection valve 12 of the engine 10 closer to the timing of bottom dead center in the intake stroke than when the suppression control is not executed. At bottom dead center in the intake stroke, the piston is at the position farthest from the in-cylinder injection valve 12. Therefore, by making the injection timing of the in-cylinder injection valve 12 closer to the timing of bottom dead center in the intake stroke, it is possible to suppress the amount of fuel adhering to the piston top surface among the amount of fuel injected by the in-cylinder injection valve 12. For example, if the injection timing when the suppression control is not executed is BTDC330°, the injection timing is set to BTDC280° by the suppression control. As a result, the amount of adhering fuel on the piston top surface exposed to the flame in the combustion stroke is suppressed, and the amount of soot emission can be suppressed.

[0028] The suppression control may be a control that stops the intermittent operation of automatically stopping and then restarting the operation of the engine 10, that is, a control that stops the idling stop function. By stopping the idling stop function, the restart of the engine 10 is restricted. As a result, an increase in the amount of soot emission due to the generation of local rich gas caused by the deterioration of fuel atomization in the cold cylinder during restart is suppressed. Incidentally, the suppression control may be a control that makes the injection timing of the in-cylinder injection valve 12 closer to the timing of bottom dead center in the intake stroke and stops the intermittent operation.

[0029] In the above embodiment, the hybrid vehicle 1 having the engine 10 and the motor 40 as the driving power source is exemplified, but it is not limited thereto. For example, a hybrid vehicle having an engine, a first motor, and a second motor as the driving power source, and further having a planetary gear mechanism for transmitting these powers to the drive wheels may be used. In the above embodiment, the hybrid vehicle 1 is described as an example, but it is not limited thereto. For example, an engine vehicle having only an engine provided as the driving power source may be used.

[0030] As described above, the embodiments of the present invention have been described in detail, but the present invention is not limited to such specific embodiments, and various modifications and changes are possible within the scope of the gist of the present invention described in the claims.

Explanation of Reference Numerals

[0031] 1 Hybrid vehicle (vehicle) 27 GPF (filter) 100 ECU (control device, determination unit, execution unit)

Claims

1. A control device for a vehicle having an engine and a filter for collecting ash and soot discharged from the engine, wherein a determination unit determines whether or not the running distance of the vehicle during driving of the engine, which correlates with the amount of ash deposited in the filter, is less than a first threshold value, and whether or not the amount of soot deposited in the filter calculated based on the operating state of the engine is less than a second threshold value; an execution unit that, when a positive determination is made by the determination unit, executes suppression control for suppressing the amount of soot discharged from the engine more than when a negative determination is made by the determination unit; and the first threshold value is set to the running distance corresponding to the amount of ash deposition at which there is a possibility that the passage of soot through the filter cannot be restricted by the ash deposited in the filter, A control device for a vehicle, wherein the second threshold value is set to the amount of soot deposition at which there is a possibility that the passage of soot through the filter cannot be restricted by the soot deposited in the filter.

2. The control device for a vehicle according to claim 1, wherein the suppression control includes control for bringing the injection timing of the in-cylinder injection valve of the engine closer to the timing of bottom dead center of the intake stroke than when the suppression control is not executed.

3. The control device for a vehicle according to claim 1 or 2, wherein the suppression control includes control for stopping intermittent operation in which the operation of the engine is automatically stopped and restarted.

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