Vehicle control device

Abstract

To provide a control device for a vehicle, which suppresses deterioration of fuel economy associated with the retard processing of ignition timing.SOLUTION: A vehicle comprises an engine that is a driving power source, and a filter for collecting exhaust particulates from the engine. A control device for the vehicle comprises: a determination unit that determines whether or not the engine continues high-load operation for a predetermined period of time or more after completion of engine warming-up in a previous trip, and a temperature rise control unit that, when the determination result by the determination unit is negative determination, allows the execution of temperature rise control on the filter by retard processing of ignition timing of the engine in the current trip, and when the determination result by the determination unit is positive determination, restricts the execution of the temperature rise control in the current trip.SELECTED DRAWING: Figure 3

Description

[Technical Field]

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

[0002] In some cases, filter regeneration control is required to prevent clogging of the filter. If the filter temperature is low when regeneration control is required, temperature rise control is performed to increase the exhaust heat quantity by retarding the ignition timing and raise the filter temperature (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-060027 Summary of the Invention [Problem to be solved by the invention]

[0004] Execution of temperature increase control by retarding the ignition timing as described above may result in a deterioration in fuel economy.

[0005] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a vehicle control device that suppresses the deterioration of fuel economy that accompanies retarding of ignition timing. [Means for solving the problem]

[0006] The above object can be achieved by a control device for a vehicle equipped with an engine as a driving power source and a filter that collects exhaust particulates from the engine, the control device comprising: a judgment unit that judges whether the engine continued to operate at high load for a predetermined period of time or more after warming up of the engine was completed in a previous trip; and a temperature rise control unit that, if the judgment result by the judgment unit is a negative judgment, allows the execution of temperature rise control of the filter by retarding the ignition timing of the engine in the current trip, and, if the judgment result by the judgment unit is a positive judgment, restricts the execution of the temperature rise control in the current trip.

[0007] The vehicle may further include a torque converter having a lock-up clutch on a power transmission path between the engine and drive wheels, and the temperature rise control unit may disengage the lock-up clutch while the temperature rise control is being performed.

[0008] The vehicle may further include a motor serving as a power source for traveling, the motor being provided on a power transmission path between the engine and the torque converter, and a battery for supplying and receiving electric power to and from the motor.

[0009] The temperature rise control unit may restrict switching from a hybrid driving mode in which the engine is driven to a motor driving mode in which the engine is stopped during execution of the temperature rise control.

[0010] The high-load operation is an operation in which the temperature of the filter rises from a temperature below the target temperature in the temperature rise control due to exhaust from the engine, and the specified time may be the time required for the temperature of the filter to reach the target temperature by continuing the high-load operation. [Effects of the Invention]

[0011] According to the present invention, it is possible to provide a vehicle control device that suppresses deterioration in fuel economy due to ignition timing retardation processing. [Brief explanation of the drawings]

[0012] [Figure 1]FIG. 1 is a schematic diagram of a hybrid vehicle. [Figure 2] FIG. 1 is a schematic diagram of an engine. [Figure 3] 10 is a flowchart showing an example of a temperature rise control limiting process. [Figure 4] 10 is a flowchart illustrating an example of a high-load history process. DETAILED DESCRIPTION OF THE INVENTION

[0013] [Hybrid vehicle configuration] FIG. 1 is a schematic diagram of a hybrid vehicle 1. The hybrid vehicle 1 is equipped with an engine 10 and a motor 15 as a power source for traveling. The engine 10 is a gasoline engine having multiple cylinders, but may also be a diesel engine. A transmission unit 11 is provided on a power transmission path from the engine 10 to drive wheels 13. The transmission unit 11 and the left and right drive wheels 13 are drivingly connected via a differential 12.

[0014] The transmission unit 11 is provided with a K0 clutch 14 and a motor 15. The motor 15 is provided on a power transmission path from the engine 10 to the drive wheels 13.

[0015] The K0 clutch 14 is provided between the engine 10 and the motor 15 in the power transmission path. The K0 clutch 14 is engaged when supplied with hydraulic pressure, connecting the power transmission between the engine 10 and the motor 15. The K0 clutch 14 is released when the hydraulic pressure supply is stopped, cutting off the power transmission between the engine 10 and the motor 15. The K0 clutch 14 is in a slip state from when torque transmission begins until it is fully engaged.

[0016] The motor 15 is connected to the battery 16 via an inverter 17. The battery 16 is a rechargeable secondary battery such as a nickel-metal hydride battery or a lithium-ion battery. The motor 15 functions as a motor that generates driving force for the vehicle in response to power supplied from the battery 16. The motor 15 also functions as a generator that generates electric power to charge the battery 16 in response to power transmitted from the engine 10 and the drive wheels 13. The electric power exchanged between the motor 15 and the battery 16 is adjusted by the inverter 17.

[0017] The transmission unit 11 is provided with a torque converter 18 and an automatic transmission 19. The torque converter 18 is a fluid coupling with a torque amplification function. The automatic transmission 19 is a stepped transmission that switches the gear ratio in multiple stages. The torque converter 18 is provided on the power transmission path between the motor 15 and the drive wheels 13. The automatic transmission 19 is provided on the power transmission path between the torque converter 18 and the drive wheels 13. The torque converter 18 is provided with a lock-up clutch (hereinafter referred to as an LU clutch) 20 that receives a supply of hydraulic pressure and engages to directly connect the motor 15 and the automatic transmission 19.

[0018] The LU clutch 20 is engaged when hydraulic pressure is supplied, connecting the power transmission between the motor 15 and the drive wheels 13. The LU clutch 20 is released when the hydraulic pressure supply is stopped. The LU clutch 20 is in a slip state from the released state to the engaged state.

[0019] The transmission unit 11 is further provided with an oil pump 21 and a hydraulic control mechanism 22. The hydraulic pressure generated by the oil pump 21 is supplied to the K0 clutch 14, the torque converter 18, the automatic transmission 19, and the LU clutch 20 via the hydraulic control mechanism 22. The hydraulic control mechanism 22 is provided with hydraulic circuits for each of the K0 clutch 14, the torque converter 18, the automatic transmission 19, and the LU clutch 20, and various hydraulic control valves for controlling the operating hydraulic pressures thereof.

[0020] A hybrid vehicle is provided with an ECU (Electronic Control Unit) 50 as a control device for the vehicle. The ECU 50 is an electronic control unit that includes a processing circuit that performs various arithmetic processes related to vehicle driving control, and a memory that stores control programs and data. The ECU 50 is an example of a vehicle control device, and functionally realizes a determination unit and a temperature rise control unit, which will be described in detail later.

[0021] The ECU 50 is connected to an ignition switch 61, a crank angle sensor 62, an air flow meter 63, air-fuel ratio sensors 64 and 65, and a water temperature sensor 66. The ignition switch 61 detects whether the ignition is on or off. The crank angle sensor 62 detects the rotation speed of the crankshaft of the engine 10. The air flow meter 63 detects the amount of intake air introduced into the engine 10. The air-fuel ratio sensors 64 and 65 detect the air-fuel ratio of the exhaust gas from the engine 10. The water temperature sensor 66 detects the temperature of the coolant that cools the engine 10.

[0022] The ECU 50 controls the operation of the engine 10 and the motor 15. Specifically, the ECU 50 controls the inverter 17 to adjust the amount of electric power exchanged between the motor 15 and the battery 16, thereby controlling the torque of the motor 15. The ECU 50 controls the operation of the K0 clutch 14, the LU clutch 20, and the automatic transmission 19 through the control of the hydraulic control mechanism 22.

[0023] The ECU 50 drives the hybrid vehicle 1 in either a motor driving mode or a hybrid driving mode. In the motor driving mode, the ECU 50 disengages the K0 clutch 14 to rotate the drive wheels 13 using the power of the motor 15. In the hybrid driving mode, the ECU 50 engages the K0 clutch 14 to rotate the drive wheels 13 using the power of at least one of the engine 10 and the motor 15. For example, when the required driving force for the hybrid vehicle 1 exceeds a driving force threshold, the mode is switched from the motor driving mode to the hybrid driving mode. Furthermore, when the charge amount of the battery 16 falls below a power threshold, the mode is switched from the motor driving mode to the hybrid driving mode.

[0024] [Engine outline] 2 is a schematic diagram of the engine 10. The engine 10 includes a cylinder block 30, a cylinder head 32, a piston 33, a connecting rod 34, a crankshaft 35, an intake passage 36, an intake valve 36v, an exhaust passage 37, and an exhaust valve 37v.

[0025] A cylindrical bore 31 is provided in the cylinder block 30. A piston 33 is housed in the bore 31 so as to be able to reciprocate. A combustion chamber C is defined by the wall surface of the bore 31, the lower surface of the cylinder head 32, and the top surface of the piston 33. The volume of the combustion chamber C increases and decreases as the piston 33 reciprocates.

[0026] The engine 10 is connected to a crankshaft 35, which is the output shaft of the engine 10, via a connecting rod 34. The connecting rod 34 and the crankshaft 35 convert the reciprocating motion of the piston 33 into the rotational motion of the crankshaft 35. The engine 10 is provided with the crank angle sensor 62 described above.

[0027] The intake passage 36 is connected to the combustion chamber C via an intake valve 36v. The exhaust passage 37 is connected to the combustion chamber C via an exhaust valve 37v. The intake passage 36 is provided with the air flow meter 63 described above.

[0028] The cylinder block 30 is provided with an in-cylinder injection valve 41D that injects fuel directly into the combustion chamber C. The intake passage 36 is provided with a port injection valve 41P that injects fuel toward the intake port. The cylinder head 32 is provided with an ignition plug 42 that ignites the mixture of intake air and fuel introduced into the combustion chamber C. Note that only one of the in-cylinder injection valve 41D and the port injection valve 41P may be provided.

[0029] The exhaust passage 37 is provided with a three-way catalyst 43 and a GPF (Gasoline Particulate Filter) 44. The three-way catalyst 43 contains catalytic metal, has oxygen storage capacity, and purifies NOx, HC, and CO. The GPF 44 is a porous ceramic structure that captures exhaust fine particles (hereinafter referred to as PM (Particulate Matter)) in the exhaust gas. The GPF 44 is an example of a filter. Note that, for example, if the engine 10 is a diesel engine, a DPF (Diesel Particulate Filter) is provided instead of the GPF 44.

[0030] An air-fuel ratio sensor 64 is provided between the three-way catalyst 43 and the GPF 44. The air-fuel ratio sensor 64 detects the air-fuel ratio of the exhaust gas discharged from the three-way catalyst 43. An air-fuel ratio sensor 65 is provided downstream of the GPF 44. The air-fuel ratio sensor 65 detects the air-fuel ratio of the exhaust gas discharged from the GPF 44.

[0031] The ECU 50 controls the operation of the engine 10 by controlling the opening of the throttle valve 40, the fuel injection amount of the in-cylinder injection valve 41D and the port injection valve 41P, the ignition timing of the spark plug 42, etc. based on the detection signals of the above-mentioned sensors.

[0032] The ECU 50 estimates the amount of PM accumulated in the GPF 44, and when the amount of PM accumulated exceeds a predetermined value, requests regeneration control of the GPF 44. The method for estimating the amount of PM accumulated may be, for example, based on the driving history of the engine 10 since the completion of the previous regeneration control, the pressure difference across the GPF 44, or other known methods. In regeneration control, oxygen for burning the accumulated PM is supplied to the GPF 44 by, for example, performing a fuel cut or controlling the air-fuel ratio to a lean air-fuel ratio.

[0033] [Temperature rise control] As described above, when a regeneration request for the GPF 44 is made and the temperature of the GPF 44 is below a predetermined value, the ECU 50 executes temperature increase control to increase the temperature of the GPF 44 to a predetermined target temperature. The temperature increase control is executed by retarding the ignition timing, which retards the ignition timing from the basic ignition timing. Retarding the ignition timing increases the amount of exhaust heat, thereby increasing the temperature of the GPF 44. The target temperature in the temperature increase control is the temperature at which PM accumulated in the GPF 44 begins to burn when oxygen is supplied to the GPF 44 due to the execution of regeneration control. Therefore, by executing regeneration control after the temperature of the GPF 44 is increased, the PM accumulated in the GPF 44 can be efficiently burned.

[0034] The ECU 50 also disengages the LU clutch 20 while the temperature rise control is being executed. This is because, if the LU clutch 20 is engaged, vibrations of the engine 10 caused by retarding the ignition timing may be transmitted to the drive wheels 13 via the LU clutch 20, which may result in a decrease in drivability. The ECU 50 also restricts switching from the hybrid driving mode to the motor driving mode while the temperature rise control is being executed. This is because if the engine 10 is stopped after switching to the motor driving mode, the GPF 44 cannot be heated and regenerated. Note that the restriction on the switching may be implemented by prohibiting the switching itself, or by changing the driving force threshold for switching from the hybrid driving mode to the motor driving mode to a lower value, or by changing the power threshold to a higher value.

[0035] As described above, the temperature rise control may reduce the driving force of the engine 10 by the amount of exhaust heat increased by the ignition timing retardation process. Furthermore, as described above, if the LU clutch 20 is disengaged while the temperature rise control is being executed, the efficiency of transmission of driving force from the engine 10 to the drive wheels 13 decreases. Furthermore, if switching to the motor driving mode is restricted while the temperature rise control is being executed, the engine 10 will continue to operate. Thus, the execution of the temperature rise control may worsen fuel economy. Therefore, the ECU 50 aims to improve fuel economy by restricting the temperature rise control when a predetermined condition is met.

[0036] [Temperature rise control limit processing] FIG. 3 is a flowchart showing an example of a process for restricting temperature rise control. This process is repeatedly executed while the ignition is on. The ECU 50 references a high load history flag to determine whether there is a high load history from the previous trip (step S1). The high load history flag is set to on if a high load operating state continues for a predetermined time or more after the engine 10 has finished warming up, as will be described in detail later. Step S1 is an example of a process executed by the determination unit. If the result in step S1 is No, the ECU 50 permits the execution of temperature rise control for the current trip (step S2). Step S2 is an example of a process executed by the temperature rise control unit.

[0037] If step S1 returns Yes, the ECU 50 restricts the execution of the temperature rise control for the current trip (step S3). In this embodiment, restricting the execution of the temperature rise control means prohibiting the execution of the temperature rise control. If high-load operation was performed in the previous trip, it is expected that high-load operation will also be performed in the current trip. Therefore, even if temperature rise control is not performed in the current trip, the engine 10 will be in a high-load operating state, and the GPF 44 will be heated to the target temperature for the temperature rise control due to the exhaust heat of the engine 10. Because temperature rise control is restricted in this way, deterioration of fuel economy is suppressed. Step S3 is an example of processing executed by the temperature rise control unit. Note that if the execution of the temperature rise control is restricted and a request for execution of regeneration control is made, the ECU 50 executes regeneration control when the temperature of the GPF 44 reaches or exceeds the target temperature for the temperature rise control due to the exhaust heat of the engine 10.

[0038] As described above, the hybrid vehicle 1 is equipped with the motor 15 and the battery 16 in addition to the engine 10. For example, the battery 16 supplies power to the motor 15, which is a driving power source, and charges the motor 15 with regenerative power. For this reason, the battery 16 is heavier than a battery installed in an internal combustion engine vehicle. In this way, the weight of the hybrid vehicle 1 is greater than that of an internal combustion engine vehicle. As a result, the load on the engine 10 in the hybrid driving mode is greater than that of an internal combustion engine vehicle. For this reason, the amount of PM emissions in the hybrid driving mode may be greater than that of an internal combustion engine vehicle. For this reason, the hybrid vehicle 1 may have to perform temperature rise control more frequently, which may result in a deterioration in fuel economy. Even in such a case, the deterioration in fuel economy can be suppressed by limiting the execution of the temperature rise control as described above.

[0039] [High load history processing] FIG. 4 is a flowchart showing an example of high load history processing. This processing is repeatedly executed while the ignition is on. The ECU 50 determines whether or not warm-up of the engine 10 has been completed (step S11). Specifically, it is determined that warm-up has been completed when the temperature of the engine 10 coolant is equal to or higher than a predetermined value. If the answer is No in step S11, this control ends.

[0040] If the result of step S11 is Yes, the ECU 50 determines whether the duration of high-load operation is equal to or longer than a predetermined time T (step S12). Here, high-load operation refers to operation in which the intake air amount is equal to or greater than a predetermined value A, and in which the temperature of the GPF 44 is increased by exhaust gas from the engine from a temperature lower than the target temperature in the temperature increase control. The predetermined time T is the time required for the temperature of the GPF 44 to reach the target temperature in the temperature increase control if such high-load operation continues. The predetermined value A and the predetermined time T may be fixed values ​​or variable values. For example, the predetermined value A and the predetermined time T may be variable values ​​that are set shorter as the predetermined value A increases, and longer as the predetermined value A decreases. The predetermined value A and the predetermined time T are determined in advance based on experimental or simulation results. If the result of step S12 is No, the ECU 50 switches the high-load history flag off (step S13). If the result of step S12 is Yes, the ECU 50 switches the high-load history flag on (step S14). With reference to the high load history flag that has been switched as described above, the ECU 50 permits or restricts the execution of the temperature rise control.

[0041] In the above embodiment, the case where the execution of the temperature rise control is prohibited has been described as an example of limiting the execution of the temperature rise control, but this is not limiting. For example, when the high load history flag is on, the execution of the temperature rise control may be limited by shortening the execution time of the temperature rise control or by reducing the amount of retardation of the ignition timing compared to when the high load history flag is off. This is because shortening the execution time or reducing the amount of retardation can also suppress deterioration of fuel economy. The amount of retardation may be reduced while shortening the execution time.

[0042] The above-described embodiments may also be applied to a control device for an engine vehicle that has only an engine as a driving power source. The above-described embodiments may also be applied to a control device for a hybrid vehicle in which an engine and a first motor are connected to a drive shaft connected to drive wheels via a planetary gear, and a second motor is connected to the drive shaft.

[0043] 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]

[0044] 1 Hybrid vehicle 10 Engine 15 motor 16 Battery 18 Torque converter 20 Lock-up clutch 44 GPF (filter) 50 ECU (vehicle control unit, judgment unit, temperature rise control unit)

Claims

[Claim 1] A control device for a vehicle including an engine as a driving power source, a filter that collects exhaust particulates from the engine, a torque converter having a lock-up clutch on a power transmission path between the engine and drive wheels, a motor as a driving power source provided on the power transmission path between the engine and the torque converter, a battery that supplies and receives electric power to and from the motor, and a K0 clutch that is disposed between the engine and the motor, The vehicle is a hybrid vehicle, a determination unit that determines whether the engine continued to operate at a high load for a predetermined period of time or more after the engine completed warming up in the previous trip; a temperature rise control unit that, when the determination result by the determination unit is a negative determination, permits execution of temperature rise control of the filter by retarding the ignition timing of the engine in the current trip, and, when the determination result by the determination unit is a positive determination, assumes that the high load operation will also be performed in the current trip and restricts execution of the temperature rise control in the current trip; Equipped with the temperature rise control unit engages the K0 clutch and releases the lock-up clutch during execution of the temperature rise control, the temperature rise control unit, during execution of the temperature rise control, restricts switching from a hybrid driving mode in which the K0 clutch is engaged and the engine is driven to a motor driving mode in which the K0 clutch is released and the engine is stopped, the high-load operation is an operation in which the temperature of the filter is increased from a temperature lower than the target temperature in the temperature increase control by exhaust gas from the engine, The vehicle control device, wherein the predetermined time is a time required for the temperature of the filter to reach the target temperature due to the continuation of the high-load operation.

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