Vehicle control device

Abstract

The invention provides a vehicle control device capable of prolonging regeneration time of a filter. When the accelerator pedal (13) is operated, the control device (70) drives the engine (20) and the plurality of MGs (31, 32) so that the engine rotation speed does not fall below the lower limit rotation speed, and increases the lower limit rotation speed when a regeneration request for the GPF (28) is generated. When the operation of the accelerator pedal (13) is released in a condition in which a regeneration request has occurred, the control device (70) starts a fuel cut process and an electric operation process. The control device (70) terminates the electric operation process and the fuel cut-off process when the engine rotation speed reaches the minimum rotation speed while the fuel cut-off process and the electric operation process are being executed.

Description

TECHNICAL FIELD

[0001] The present application relates to a vehicle control device applied to a vehicle equipped with an engine and a motor generator. BACKGROUND

[0002] The control device disclosed in Patent Literature 1 is applied to a vehicle equipped with an engine in which a filter that traps particulate matter contained in exhaust gas is disposed in an exhaust passage, and a motor generator that is coupled to a crankshaft of the engine in a state in which power can be transmitted. The control device executes electric driving that suppresses a drop in a rotational speed of the crankshaft, i.e., an engine rotational speed, by driving the motor generator in a case where fuel cut based on a request to regenerate the filter is executed.

[0003] PRIOR ART DOCUMENTS

[0004] PATENT LITERATURE

[0005] Patent Literature 1: Japanese Patent Application Publication No. 2015-202832 SUMMARY

[0006] PROBLEMS TO BE SOLVED BY THE INVENTION

[0007] Even if the electric driving is executed while the fuel cut is performed as described above, the engine rotational speed gradually decreases. Also, when the engine rotational speed reaches a minimum rotational speed, the fuel cut ends and fuel supply to a combustion chamber of the engine is started again, so the regeneration of the filter stops. That is, when the execution time of the fuel cut is short, the filter cannot be sufficiently regenerated.

[0008] MEANS FOR SOLVING THE PROBLEMS

[0009] A vehicle control device for solving the above-described problem is applied to a vehicle equipped with an engine provided with a filter that traps particulate matter contained in exhaust gas in an exhaust passage, and an electric motor generator coupled to a crankshaft of the engine in a state capable of transmitting power. The vehicle control device is provided with a processing circuit. The processing circuit drives the engine and the electric motor generator in such a manner that an engine rotation speed is not lower than a lower limit rotation speed in a case where an accelerator pedal is operated so that the engine performs load operation. The processing circuit increases the lower limit rotation speed in a case where a request for regenerating the filter, that is, a regeneration request, is generated, as compared with a case where the regeneration request is not generated. The processing circuit starts a fuel cut processing of stopping supply of fuel to a cylinder of the engine when operation of the accelerator pedal is released in a state where the engine performs load operation. The processing circuit starts an electric operation processing of suppressing a decrease in the engine rotation speed by driving the electric motor generator in a case where the fuel cut processing is started in a state where the regeneration request is generated. The processing circuit ends the electric operation processing and ends the fuel cut processing and starts supply of fuel to the cylinder again when the engine rotation speed becomes a minimum rotation speed in a state where the fuel cut processing and the electric operation processing are performed.

[0010] Effects of Invention

[0011] The above-described vehicle control device has an effect of being able to extend a regeneration time of the filter. BRIEF DESCRIPTION OF DRAWINGS

[0012] Figure 1 is a schematic configuration view that shows a vehicle provided with a control device of one embodiment of a vehicle control device.

[0013] Figure 2 is a flowchart that shows a series of processes executed by the control device of Figure 1 .

[0014] Figure 3 is a flowchart that shows a series of processes executed by the control device of Figure 1 .

[0015] Figure 4 Figs. 23 (a) to (e) are timing charts at the time of regeneration of a filter provided in an exhaust passage of an engine of a vehicle of Figure 1 . DETAILED DESCRIPTION

[0016] Hereinafter, one embodiment of a vehicle control device will be described with reference to Figures 1-4 .

[0017] <Structure of Vehicle>

[0018] Figure 1 A vehicle 10 equipped with a control device 70 is shown. The control device 70 corresponds to "vehicle control device". The vehicle 10 includes an engine 20, a first motor generator 31, a second motor generator 32, a planetary gear mechanism 40, a power transmission mechanism 50, a plurality of wheels 11, a converter 33, and a storage battery 34. Hereinafter, the first motor generator 31 is described as "first MG 31", and the second motor generator 32 is described as "second MG 32". In the present embodiment, the first MG 31 and the second MG 32 correspond to "motor generator" that is linked to a crankshaft 22 of the engine 20 in a state capable of transmitting power.

[0019] The engine 20 is equipped with a plurality of cylinders 21, the crankshaft 22, a plurality of ignition devices 23, a plurality of fuel injection valves 24, an intake passage 25, and an exhaust passage 26. In the plurality of cylinders 21, a mixture gas containing air introduced from the intake passage 25 and fuel injected by the corresponding fuel injection valve 24 is generated. The mixture gas is combusted by spark discharge of the ignition device 23 in the plurality of cylinders 21, and the crankshaft 22 is rotated.

[0020] The exhaust gas generated by combustion of the mixture gas in the plurality of cylinders 21 is discharged to the exhaust passage 26. The catalyst 27 and a gasoline particulate filter 28 are provided in the exhaust passage 26. The catalyst 27 oxidizes CO and HC contained in the exhaust gas flowing in the exhaust passage 26, or reduces NOx. The gasoline particulate filter 28 is disposed in a portion of the exhaust passage 26 that is more downstream than the catalyst 27. The gasoline particulate filter 28 traps particulate matter contained in the exhaust gas flowing in the exhaust passage 26. Hereinafter, the gasoline particulate filter 28 is described as "GPF 28".

[0021] The planetary gear mechanism 40 is equipped with a sun gear 41, a ring gear 42, a pinion 43, and a carrier 44. The crankshaft 22 of the engine 20 is linked to the pinion 43 via the carrier 44. The output shaft 31a of the first MG 31 is linked to the sun gear 41. Also, the planetary gear mechanism 40 can transmit output to the power transmission mechanism 50 via the ring gear 42.

[0022] The power transmission mechanism 50 includes a countershaft drive gear 51, a countershaft driven gear 52, a reduction gear 53, a final drive gear 54, a final driven gear 55, and a differential 56. The countershaft drive gear 51 can rotate integrally with the ring gear 42. The countershaft drive gear 51 and the reduction gear 53 are engaged with the countershaft driven gear 52. The reduction gear 53 can rotate integrally with the output shaft 32a of the second MG 32.

[0023] The final drive gear 54 can rotate integrally with the countershaft driven gear 52. The final driven gear 55 is engaged with the final drive gear 54. The output of the final driven gear 55 is transmitted to the plurality of wheels 11 via the differential 56.

[0024] The first MG 31 and the second MG 32 receive and supply electric power to and from a storage battery 34 via a converter 33. The converter 33 converts a terminal voltage of the storage battery 34, which is a direct-current voltage source, into an alternating-current current and outputs. That is, the storage battery 34 is capable of storing electric power supplied to the plurality of MGs 31, 32.

[0025] <Control device>

[0026] An example of the control device 70 is an electronic control device. In this case, the control device 70 has a CPU 71 and a memory 72 that stores a program executed by the CPU 71. By the CPU 71 executing the program of the memory 72, the control device 70 is capable of controlling the engine 20 and the plurality of MGs 31, 32. In the present embodiment, the CPU 71 corresponds to the "processing circuitry".

[0027] Detection signals of a plurality of sensors are input to the control device 70. The plurality of sensors include a crank angle sensor 81 and an accelerator opening degree sensor 82. The crank angle sensor 81 is a sensor that detects a rotation angle of the crankshaft 22 and outputs a detection signal corresponding to a rotation speed of the crankshaft 22. The accelerator opening degree sensor 82 outputs a detection signal corresponding to an opening degree of the accelerator pedal 13. Hereinafter, the rotation speed of the crankshaft 22 obtained on the basis of the detection signal of the crank angle sensor 81 is described as "engine speed Ne". The opening degree of the accelerator pedal 13 obtained on the basis of the detection signal of the accelerator opening degree sensor 82 is described as "accelerator opening degree AC".

[0028] In a case where the accelerator pedal 13 is operated so that the engine 20 performs load operation, the CPU 71 drives the engine 20 and the plurality of MGs 31, 32 in such a manner that the engine speed Ne is not lower than a lower limit speed NeThB. An engine speed larger than a minimum rotation speed NeThA of the engine 20 is set as the lower limit speed NeThB. The minimum rotation speed NeThA is described later.

[0029] In a case where the engine 20 performs load operation, sometimes the operation of the accelerator pedal 13 by the driver of the vehicle 10 is released. In this case, in a case where the engine speed Ne is larger than the minimum rotation speed NeThA, the CPU 71 starts fuel cut processing. In the fuel cut processing, the CPU 71 stops the supply of fuel into the plurality of cylinders 21 by stopping the fuel injection of the plurality of fuel injection valves 24.

[0030] In a case where the fuel cut processing is executed, the engine speed Ne decreases. If the fuel cut processing is continued even though the engine speed Ne is smaller than the minimum speed NeThA, the rotation of the crankshaft 22 will stop. Therefore, when the engine speed Ne reaches the minimum speed NeThA by execution of the fuel cut processing, the CPU 71 ends the fuel cut processing. In this case, the CPU 71 starts the supply of fuel into the plurality of cylinders 21 again by starting the fuel injection of the plurality of fuel injection valves 24 again. Thus, the CPU 71 can make the engine speed Ne larger than the minimum speed NeThA.

[0031] Here, in a case where the engine 20 is subjected to load operation, a request for regenerating the GPF 28, i.e., a regeneration request, is sometimes generated. In a case where the CPU 71 executes the fuel cut processing in a state where the regeneration request is generated, the CPU 71 executes the mot operation processing together with the fuel cut processing. In the mot operation processing, the control device 70 suppresses the decrease of the engine speed Ne, for example, by causing the first MG 31 to be driven.

[0032] When the crankshaft 22 rotates in a state where the supply of fuel into the plurality of cylinders 21 is stopped, the air discharged from the plurality of cylinders 21 to the exhaust passage 26 is supplied to the GPF 28. Thus, the regeneration of the GPF 28 is performed. Therefore, when the length of time during which the fuel cut processing is executed is short, the regeneration of the GPF 28 cannot be sufficiently performed.

[0033] Therefore, in the control device 70, in a case where the regeneration request is generated, the CPU 71 increases the lower limit speed NeThB compared to a case where the regeneration request is not generated. Thus, in a case where the accelerator pedal 13 is operated and the engine 20 is subjected to load operation, the CPU 71 can maintain a state where the engine speed Ne is relatively large. Therefore, the CPU 71 can start the fuel cut processing and the mot operation processing from a state where the engine speed Ne is relatively large. As a result, the CPU 71 can make the execution time of the fuel cut processing relatively long.

[0034] <Setting processing of lower limit speed>

[0035] Reference Signs Figure 2 The setting processing of the lower limit speed NeThB executed by the CPU 71 will be described. The CPU 71 repeatedly executes this setting processing every predetermined control period.

[0036] In step S11, the CPU 71 determines whether the fuel cut processing is being executed. In a case where the CPU 71 is executing the fuel cut processing (S11: YES), the CPU 71 temporarily ends this setting processing. On the other hand, in a case where the CPU 71 is not executing the fuel cut processing (S11: NO), the CPU 71 causes the processing to proceed to step S13.

[0037] In step S13, the CPU 71 determines whether a request for reproduction of the filter 28 has been made. In the case where a request for reproduction has been made (S13: YES), the CPU 71 transfers the process to step S15. On the other hand, in the case where a request for reproduction has not been made (S13: NO), the CPU 71 transfers the process to step S17.

[0038] In step S15, the CPU 71 determines whether the discharge control limit electric power Wout of the battery 34 is less than the threshold value WoutTh. In the case where the crankshaft 22 is rotated by driving of the first MG 31, if the discharge control limit electric power Wout is relatively low, the driving force transmitted from the first MG 31 to the crankshaft 22 is small, and therefore the effect of suppressing the decrease in engine speed is insufficient. Therefore, the discharge control limit electric power, which becomes a criterion for determining whether the decrease in engine speed can be sufficiently suppressed, is set to the threshold value WoutTh. In the case where the discharge control limit electric power Wout is less than the threshold value WoutTh (S15: YES), the CPU 71 transfers the process to step S19. On the other hand, in the case where the discharge control limit electric power Wout is the threshold value WoutTh or more (S15: NO), the CPU 71 transfers the process to step S17.

[0039] In step S17, the CPU 71 sets the first rotational speed Ne1 to the lower limit rotational speed NeThB. Thereafter, the CPU 71 temporarily ends the setting process.

[0040] In step S19, the CPU 71 sets the second rotational speed Ne2 to the lower limit rotational speed NeThB. The second rotational speed Ne2 is greater than the first rotational speed Ne1. Thereafter, the CPU 71 temporarily ends the setting process.

[0041] <Filter reproduction process>

[0042] Reference Figure 3 The filter reproduction process performed by the CPU 71 will be described. The CPU 71 repeatedly performs this filter reproduction process every predetermined control period.

[0043] In step S31, the CPU 71 determines whether the operation of the accelerator pedal 13 has been released. In the case where the operation has been released (S31: YES), the CPU 71 transfers the process to step S33. On the other hand, in the case where the operation has not been released (S31: NO), the CPU 71 transfers the process to step S35.

[0044] In step S33, CPU 71 determines whether the engine speed Ne is above the minimum speed NeThA. A speed Ne0, which is lower than the first speed Ne1, is set as the minimum speed NeThA. If the engine speed Ne is above the minimum speed NeThA (S33: Yes), CPU 71 transfers the process to step S37. On the other hand, if the engine speed Ne is less than the minimum speed NeThA (S33: No), CPU 71 transfers the process to step S35.

[0045] In step S35, CPU71 terminates the fuel cutoff process and the electric operation process. That is, while CPU71 is performing the fuel cutoff process, CPU71 restarts the fuel supply to the multiple cylinders 21 by restarting the operation of the multiple fuel injection valves 24. Additionally, if CPU71 is performing the electric operation process, CPU71 terminates the electric operation process. Afterwards, CPU71 temporarily terminates the filter regeneration process.

[0046] In step S37, CPU 71 performs a fuel cut-off process. In the next step S39, CPU 71 determines whether a regeneration request for GPF 28 has been generated. If a regeneration request has been generated (S39: Yes), CPU 71 transfers the process to step S41. On the other hand, if no regeneration request has been generated (S39: No), CPU 71 temporarily terminates the filter regeneration process. That is, CPU 71 performs a fuel cut-off process, but does not perform an electric operation process. In step S41, CPU 71 performs an electric operation process. Afterward, CPU 71 temporarily terminates the filter regeneration process.

[0047] <Function and Effects of This Implementation Method>

[0048] Reference Figure 4 The function and effects of this implementation method will be explained.

[0049] like Figure 4 As shown in (a) to (e), at time t11, when the driver of vehicle 10 is operating the accelerator pedal 13 and the engine 20 is under load, a regeneration request for GPF 28 is generated. No regeneration request is generated before time t11. Therefore, the first speed Ne1 is set to the lower limit speed NeThB. However, after time t11, a regeneration request for GPF 28 is generated, so the second speed Ne2 is set to the lower limit speed NeThB. That is, as a regeneration request is generated, the lower limit speed NeThB increases.

[0050] At timing t12 later, the operation of the accelerator pedal 13 is released. Since the engine speed Ne is greater than the minimum engine speed NeThA, the fuel cut processing is started. When the fuel cut processing is executed, the engine speed Ne gradually decreases. Therefore, the motoring processing is executed.

[0051] In the case where the fuel cut processing is executed, air is discharged from the plurality of cylinders 21 to the exhaust passage 26. By supplying such air to the GPF 28, the regeneration of the GPF 28 is promoted. In addition, since the driving force of the first MG 31 is transmitted to the crankshaft 22, as shown by the solid line in (b) of FIG. 10, the decrease of the engine speed Ne is suppressed. Figure 4

[0052] Further, in the case where the fuel cut processing is executed, the engine speed Ne is decreased. Therefore, the motoring processing is executed. Figure 4 In (b) of FIG. 10, the progress of the engine speed Ne in the comparative example is indicated by the double-dot chain line. In the comparative example, even if the regeneration request of the GPF 28 is generated, the lower limit engine speed NeThB is maintained as the first engine speed Ne1.

[0053] In such a comparative example, in the case where the accelerator pedal 13 is operated and the engine 20 performs the load operation, the engine speed Ne is lower than the second engine speed Ne2. This is because the first engine speed Ne1 is set as the lower limit engine speed NeThB. Then, at timing t12, the fuel cut processing and the motoring processing are started. In the comparative example, compared with the case of the present embodiment, the fuel cut processing and the motoring processing are started in a state where the engine speed Ne is relatively small. Therefore, in the present embodiment, at timing t14, the engine speed Ne reaches the minimum engine speed NeThA, whereas in the comparative example, at timing t13, the engine speed Ne reaches the minimum engine speed NeThA. Timing t13 is a timing before timing t14. That is, the time during which air can be supplied to the GPF 28 is relatively short, and therefore, the time during which the GPF 28 can be regenerated is relatively short.

[0054] In contrast, in the present embodiment, the fuel cut processing and the motoring processing can be started from a state where the engine speed Ne is relatively large. Therefore, compared with the case of the comparative example, the time during which air can be supplied to the GPF 28 is lengthened. Therefore, in the present embodiment, the regeneration time of the GPF 28 can be extended.

[0055] Here, in the case where the motoring processing is executed in a state where the discharge control limit electric power Wout of the battery 34 is low, the decrease of the engine speed Ne cannot be sufficiently suppressed. Therefore, in the case where the discharge control limit electric power Wout is smaller than the threshold value WoutTh, the lower limit engine speed NeThB is made larger. Thereby, the time during which the GPF 28 can be regenerated can be suppressed from becoming shorter in correspondence with the start of the fuel cut processing and the motoring processing in a state where the engine speed Ne is relatively large. ​

[0056] <Modification example>

[0057] The above-described embodiments can be implemented as follows. The above-described embodiments and the following modification examples can be implemented in combination with each other within a range in which there is no technical inconsistency.

[0058] • The CPU 71 can set the lower limit rotation speed NeThB in accordance with the discharge control limit electric power Wout at the start time of the fuel cut processing.

[0059] • It can also be that, in a case where the regeneration request of the GPF 28 is generated, the CPU 71 sets the second rotation speed Ne2 to the lower limit rotation speed NeThB regardless of whether the discharge control limit electric power Wout is below the threshold value WoutTh.

[0060] • The vehicle to which the vehicle control device is applied can be a vehicle provided with the engine 20 and the motor generator linked to the crankshaft 22 in a state capable of transmitting power, and can also be a vehicle of a structure different from the vehicle 10 shown in FIG. 1. Figure 1

[0061] • The control device 70 is not limited to being provided with a CPU and a ROM to execute software processing. That is, the control device 70 can be any of the following (a), (b), and (c).

[0062] (a) The control device 70 is provided with one or more processors that execute various processes according to computer programs. The processors include a CPU and a memory such as a RAM and a ROM. The memory stores program codes or instructions that cause the CPU to execute the processes. The memory, which is a computer-readable medium, includes all available media that can be accessed by a general-purpose or special-purpose computer.

[0063] (b) The control device 70 is provided with one or more dedicated hardware circuits that execute various processes. As the dedicated hardware circuits, for example, an integrated circuit for a specific purpose, that is, an ASIC or an FPGA can be cited. The ASIC is an abbreviation for "Application Specific Integrated Circuit", and the FPGA is an abbreviation for "Field Programmable Gate Array".

[0064] (c) The control device 70 is provided with one or more processors that execute part of various processes according to computer programs and one or more dedicated hardware circuits that execute the remaining processes in the various processes.

[0065] Explanation of reference numerals

[0066] ​10 vehicle, 13 accelerator pedal, 20 engine, 21 cylinder, 22 crankshaft, 26 exhaust passage, 28 GPF, 31, 32 MG, 34 storage battery, 70 control device, 71 CPU.

Claims

1. A vehicle control device applied to a vehicle, the vehicle comprising: an engine, a filter for capturing particulate matter contained in exhaust gas provided in an exhaust passage; and an electric generator connected to the crankshaft of the engine in a power-transmitting state. The vehicle control device includes processing circuitry. The processing circuit is configured as follows: When the accelerator pedal is operated and the engine is under load, the engine and the electric generator are driven in a manner that keeps the engine speed from falling below the lower limit speed. When a regeneration requirement arises, the lower speed limit is increased compared to when the regeneration requirement is not present. When the accelerator pedal is released while the engine is under load, a fuel cut-off process begins, stopping the supply of fuel to the engine cylinders. When the fuel cut-off process is performed under the condition that the regeneration requirement is generated, an electric operation process is initiated to suppress the decrease in engine speed by driving the electric generator. When the engine speed reaches its minimum speed while the fuel cut-off process and the electric operation process are being performed, the electric operation process ends, and the fuel cut-off process ends, and fuel is supplied to the cylinder again.

2. The vehicle control device according to claim 1, wherein, The processing circuit is configured to, when the regeneration request is generated, increase the lower limit speed compared to the case where the discharge control limit power of the battery storing the power supplied to the electric generator is less than a threshold.

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