Vehicle control device

Abstract

To prolong the regeneration time of a filter.SOLUTION: When an accelerator pedal 13 is operated, the control device 70 drives the engine 20 and the plurality of MG31 32 so that the engine rotation speed does not fall below the lower limit rotation speed, and increases the lower limit rotation speed when the regeneration request of the GPF28 is generated. When the operation of the accelerator pedal 13 is canceled under the situation where the regeneration request is occurring, the control device 70 starts the fuel cut-off process and the motoring process. When the engine rotation speed reaches the minimum rotation speed in a situation where the fuel cut-off process and the motoring process are being executed, the control device 70 ends the motoring process and the fuel cut-off process.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a vehicle control device that is applied to a vehicle equipped with an engine and a motor generator. [Background technology]

[0002] The control device disclosed in Patent Document 1 is applied to a vehicle equipped with an engine in which a filter for capturing particulate matter contained in the exhaust is arranged in the exhaust passage, and a motor generator connected to the engine crankshaft in a state in which power can be transmitted. When a fuel cut is executed based on a request to regenerate the filter, the control device drives the motor generator to perform motoring, which suppresses a decrease in the engine rotation speed, which is the rotation speed of the crankshaft. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2015-202832 Summary of the Invention [Problem to be solved by the invention]

[0004] Even when motoring while fuel is cut as described above, the engine speed gradually decreases. When the engine speed reaches its minimum speed, the fuel cut ends and fuel supply to the engine's combustion chamber resumes, stopping filter regeneration. In other words, if the fuel cut is performed for a short period of time, the filter will not be regenerated sufficiently. [Means for solving the problem]

[0005] A vehicle control device for solving the above problem is applied to a vehicle including an engine having an exhaust passage equipped with a filter for capturing particulate matter contained in the exhaust, and a motor generator connected to the engine crankshaft in a state in which power can be transmitted. The vehicle control device includes a processing circuit. When an accelerator pedal is operated to cause the engine to operate under load, the processing circuit drives the engine and the motor generator so that the engine rotation speed does not fall below a lower limit rotation speed. When a regeneration request for regenerating the filter is issued, the processing circuit increases the lower limit rotation speed compared to when the regeneration request is not issued. When the accelerator pedal is released while the engine is operating under load, the processing circuit initiates a fuel cut process to stop fuel supply to the engine cylinders. When the fuel cut process is initiated while the regeneration request is issued, the processing circuit initiates a motoring process to drive the motor generator to suppress a decrease in the engine rotation speed. When the engine rotation speed reaches the minimum rotation speed while the fuel cut processing and the motoring processing are being performed, the processing circuit terminates the motoring processing and also terminates the fuel cut processing and resumes fuel supply to the cylinders. [Effects of the Invention]

[0006] The vehicle control device has the effect of extending the filter regeneration time. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a schematic diagram showing the configuration of a vehicle equipped with a control device that is one embodiment of a vehicle control device. [Figure 2] FIG. 2 is a flowchart showing a series of processes executed by the control device of FIG. [Figure 3] FIG. 3 is a flowchart showing a series of processes executed by the control device of FIG. [Figure 4]In FIG. 4, (a) to (e) are timing charts for regenerating a filter installed in an exhaust passage of an engine equipped in the vehicle of FIG. DETAILED DESCRIPTION OF THE INVENTION

[0008] An embodiment of a vehicle control device will be described below with reference to FIGS. <Vehicle configuration> FIG. 1 shows a vehicle 10 equipped with a control device 70. The control device 70 corresponds to a "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, an inverter 33, and a battery 34. Hereinafter, the first motor generator 31 will be referred to as a "first MG 31," and the second motor generator 32 will be referred to as a "second MG 32." In this embodiment, the first MG 31 and the second MG 32 correspond to "motor generators" that are connected to the crankshaft 22 of the engine 20 in a state capable of transmitting power.

[0009] The engine 20 includes a plurality of cylinders 21, a 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, an air-fuel mixture is generated that contains air introduced from the intake passage 25 and fuel injected by the corresponding fuel injection valve 24. The air-fuel mixture is combusted in the plurality of cylinders 21 by spark discharge from the ignition devices 23, causing the crankshaft 22 to rotate.

[0010] Exhaust gas generated by combustion of the air-fuel mixture in the multiple cylinders 21 is discharged into an exhaust passage 26. A catalyst 27 and a gasoline particulate filter 28 are installed in the exhaust passage 26. The catalyst 27 oxidizes CO and HC and reduces NOx contained in the exhaust gas flowing through the exhaust passage 26. The gasoline particulate filter 28 is arranged in a portion of the exhaust passage 26 downstream of the catalyst 27. The gasoline particulate filter 28 captures particulate matter contained in the exhaust gas flowing through the exhaust passage 26. Hereinafter, the gasoline particulate filter 28 will be referred to as "GPF 28."

[0011] The planetary gear mechanism 40 includes a sun gear 41, a ring gear 42, a pinion gear 43, and a carrier 44. The crankshaft 22 of the engine 20 is connected to the pinion gear 43 via the carrier 44. The output shaft 31a of the first MG 31 is connected to the sun gear 41. The planetary gear mechanism 40 is capable of transmitting output to the power transmission mechanism 50 via the ring gear 42.

[0012] The power transmission mechanism 50 includes a counter drive gear 51, a counter driven gear 52, a reduction gear 53, a final drive gear 54, a final driven gear 55, and a differential 56. The counter drive gear 51 can rotate integrally with the ring gear 42. The counter drive gear 51 is meshed with the counter drive gear 51 and the reduction gear 53. The reduction gear 53 can rotate integrally with the output shaft 32a of the second MG 32.

[0013] The final drive gear 54 can rotate integrally with the counter driven gear 52. The final driven gear 55 is meshed with the final drive gear 54. The output of the final driven gear 55 is transmitted to the plurality of wheels 11 via a differential 56.

[0014] The first MG 31 and the second MG 32 exchange power with a battery 34 via an inverter 33. The inverter 33 converts the terminal voltage of the battery 34, which is a DC voltage source, into AC current and outputs it. In other words, the battery 34 can store power to be supplied to the multiple MGs 31 and 32.

[0015] <Control device> 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. The CPU 71 executes the program in the memory 72, thereby enabling the control device 70 to control the engine 20 and the multiple MGs 31 and 32. In this embodiment, the CPU 71 corresponds to the "processing circuit."

[0016] Detection signals from multiple sensors are input to the control device 70. The multiple sensors include a crank angle sensor 81 and an accelerator position sensor 82. The crank angle sensor 81 is a sensor that detects the rotation angle of the crankshaft 22 and outputs a detection signal corresponding to the rotation speed of the crankshaft 22. The accelerator position sensor 82 outputs a detection signal corresponding to the position of the accelerator pedal 13. Hereinafter, the rotation speed of the crankshaft 22 based on the detection signal of the crank angle sensor 81 will be referred to as the "engine rotation speed Ne." The position of the accelerator pedal 13 based on the detection signal of the accelerator position sensor 82 will be referred to as the "accelerator position AC."

[0017] When the accelerator pedal 13 is operated and the engine 20 is operated under load, the CPU 71 drives the engine 20 and the multiple MGs 31, 32 so that the engine rotation speed Ne does not fall below a lower limit rotation speed NeThB. An engine rotation speed higher than the minimum rotation speed NeThA of the engine 20 is set as the lower limit rotation speed NeThB. The minimum rotation speed NeThA will be described later.

[0018] While the engine 20 is operating under load, the driver of the vehicle 10 may release the accelerator pedal 13. In this case, if the engine speed Ne is greater than the minimum engine speed NeThA, the CPU 71 starts a fuel cut process. In the fuel cut process, the CPU 71 stops fuel injection from the fuel injection valves 24, thereby stopping the fuel supply to the cylinders 21.

[0019] When the fuel cut process is being executed, the engine speed Ne decreases. If the fuel cut process is continued even when the engine speed Ne becomes less than the minimum rotation speed NeThA, the rotation of the crankshaft 22 will stop. Therefore, the CPU 71 ends the fuel cut process when the engine speed Ne reaches the minimum rotation speed NeThA through the execution of the fuel cut process. In this case, the CPU 71 resumes fuel injection from the plurality of fuel injection valves 24, thereby resuming fuel supply to the plurality of cylinders 21. In this way, the CPU 71 can make the engine speed Ne higher than the minimum rotation speed NeThA.

[0020] When the engine 20 is operating under load, a regeneration request may be issued to regenerate the GPF 28. If the CPU 71 executes a fuel cut process while a regeneration request is issued, the CPU 71 executes a motoring process in addition to the fuel cut process. In the motoring process, the control device 70 suppresses a decrease in the engine rotation speed Ne by, for example, driving the first MG 31.

[0021] When the crankshaft 22 rotates with fuel supply to the cylinders 21 stopped, air discharged from the cylinders 21 into the exhaust passage 26 is supplied to the GPF 28. This regenerates the GPF 28. Therefore, if the duration of the fuel cut process is short, the GPF 28 will not be regenerated sufficiently.

[0022] Therefore, in the control device 70, the CPU 71 increases the lower limit rotation speed NeThB when a regeneration request is issued compared to when no regeneration request is issued. As a result, the CPU 71 can maintain a relatively high engine rotation speed Ne when the accelerator pedal 13 is operated and the engine 20 is operating under load. Therefore, the CPU 71 can start the fuel cut process and motoring process while the engine rotation speed Ne is relatively high. As a result, the CPU 71 can relatively extend the execution time of the fuel cut process.

[0023] <Lower limit rotation speed setting process> The process of setting the lower limit rotation speed NeThB executed by the CPU 71 will be described with reference to Fig. 2. The CPU 71 repeatedly executes this setting process at every predetermined control period.

[0024] In step S11, the CPU 71 determines whether or not a fuel cut process is being executed. If the CPU 71 is executing the fuel cut process (S11: YES), the CPU 71 temporarily ends the setting process. On the other hand, if the CPU 71 is not executing the fuel cut process (S11: NO), the CPU 71 proceeds to step S13.

[0025] In step S13, the CPU 71 determines whether or not a regeneration request has been issued for the GPF 28. If a regeneration request has been issued (S13: YES), the CPU 71 proceeds to step S15. On the other hand, if a regeneration request has not been issued (S13: NO), the CPU 71 proceeds to step S17.

[0026] In step S15, the CPU 71 determines whether the discharge control limit power Wout of the battery 34 is less than a threshold value WoutTh. When the crankshaft 22 is rotated by driving the first MG 31, if the discharge control limit power Wout is relatively low, the driving force transmitted from the first MG 31 to the crankshaft 22 is small, and the effect of suppressing a decrease in engine rotation speed is not sufficient. Therefore, the discharge control limit power, which serves as a criterion for determining whether a decrease in engine rotation speed can be sufficiently suppressed, is set to a threshold value WoutTh. If the discharge control limit power Wout is less than the threshold value WoutTh (S15: YES), the CPU 71 proceeds to step S19. On the other hand, if the discharge control limit power Wout is equal to or greater than the threshold value WoutTh (S15: NO), the CPU 71 proceeds to step S17.

[0027] In step S17, the CPU 71 sets the first rotation speed Ne1 to the lower limit rotation speed NeThB, and then temporarily ends the setting process. In step S19, the CPU 71 sets the second rotation speed Ne2 to the lower limit rotation speed NeThB. The second rotation speed Ne2 is higher than the first rotation speed Ne1. Thereafter, the CPU 71 temporarily ends the setting process.

[0028] <Filter regeneration process> The filter regeneration process executed by the CPU 71 will be described with reference to Fig. 3. The CPU 71 repeatedly executes the filter regeneration process at predetermined control intervals.

[0029] In step S31, the CPU 71 determines whether or not the operation of the accelerator pedal 13 has been released. If the operation has been released (S31: YES), the CPU 71 proceeds to step S33. On the other hand, if the operation has not been released (S31: NO), the CPU 71 proceeds to step S35.

[0030] In step S33, the CPU 71 determines whether the engine rotation speed Ne is equal to or greater than the minimum rotation speed NeThA. A rotation speed Ne0, which is lower than the first rotation speed Ne1, is set as the minimum rotation speed NeThA. If the engine rotation speed Ne is equal to or greater than the minimum rotation speed NeThA (S33: YES), the CPU 71 proceeds to step S37. On the other hand, if the engine rotation speed Ne is less than the minimum rotation speed NeThA (S33: NO), the CPU 71 proceeds to step S35.

[0031] In step S35, the CPU 71 ends the fuel cut process and the motoring process. That is, if the CPU 71 was executing the fuel cut process, the CPU 71 restarts the operation of the plurality of fuel injection valves 24, thereby restarting the fuel supply to the plurality of cylinders 21. Also, if the CPU 71 was executing the motoring process, the CPU 71 ends the motoring process. Thereafter, the CPU 71 temporarily ends the filter regeneration process.

[0032] In step S37, the CPU 71 executes a fuel cut process. In the following step S39, the CPU 71 determines whether a regeneration request for the GPF 28 has been issued. If a regeneration request has been issued (S39: YES), the CPU 71 proceeds to step S41. On the other hand, if a regeneration request has not been issued (S39: NO), the CPU 71 temporarily terminates the filter regeneration process. In other words, the CPU 71 executes the fuel cut process but does not execute the motoring process. In step S41, the CPU 71 executes the motoring process. Thereafter, the CPU 71 temporarily terminates the filter regeneration process.

[0033] <Actions and Effects of This Embodiment> The operation and effects of this embodiment will be described with reference to FIG. As shown in FIGS. 4(a) to 4(e), a regeneration request for the GPF 28 is generated at timing t11 while the engine 20 is operating under load because the driver of the vehicle 10 is operating the accelerator pedal 13. No regeneration request has been generated before timing t11. Therefore, the first rotation speed Ne1 is set to the lower limit rotation speed NeThB. However, after timing t11, a regeneration request for the GPF 28 is generated, and the second rotation speed Ne2 is set to the lower limit rotation speed NeThB. In other words, the lower limit rotation speed NeThB increases as the regeneration request is generated.

[0034] At a subsequent timing t12, the accelerator pedal 13 is released. Since the engine rotation speed Ne is greater than the minimum rotation speed NeThA, the fuel cut process is initiated. While the fuel cut process is being executed, the engine rotation speed Ne gradually decreases. Therefore, the motoring process is executed.

[0035] When the fuel cut process is being performed, air is discharged from the cylinders 21 into the exhaust passage 26. This air is supplied to the GPF 28, thereby promoting regeneration of the GPF 28. Furthermore, because the driving force of the first MG 31 is transmitted to the crankshaft 22, a decrease in the engine rotation speed Ne is suppressed, as indicated by the thick solid line in FIG. 4(b).

[0036] 4(b), the transition of the engine rotation speed Ne in the comparative example is shown by a two-dot chain line. In the comparative example, even if a regeneration request for the GPF 28 is generated, the lower limit rotation speed NeThB is maintained at the first rotation speed Ne1.

[0037] In this comparative example, when the accelerator pedal 13 is operated and the engine 20 is operating under load, the engine speed Ne is lower than the second speed Ne2. This is because the first speed Ne1 is set to the lower limit speed NeThB. Then, the fuel cut process and motoring process are initiated at timing t12. In the comparative example, the fuel cut process and motoring process are initiated when the engine speed Ne is relatively low compared to the present embodiment. Therefore, in the present embodiment, the engine speed Ne reaches the minimum speed NeThA at timing t14, whereas in the comparative example, the engine speed Ne reaches the minimum speed NeThA at timing t13. Timing t13 occurs before timing t14. In other words, 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.

[0038] In contrast, in this embodiment, the fuel cut process and motoring process can be started when the engine rotation speed Ne is relatively high. Therefore, the time during which air can be supplied to the GPF 28 is longer than in the comparative example. Therefore, in this embodiment, the regeneration time of the GPF 28 can be extended.

[0039] Here, if the motoring process is performed when the discharge control power limit Wout of the battery 34 is low, the decrease in the engine rotation speed Ne is not sufficiently suppressed. Therefore, when the discharge control power limit Wout is less than the threshold value WoutTh, the lower limit rotation speed NeThB is increased. This prevents the time available for regenerating the GPF 28 from being shortened by the time the fuel cut process and motoring process are started when the engine rotation speed Ne is relatively high.

[0040] <Example of change> The above embodiment can be modified as follows: The above embodiment and the following modifications can be combined with each other within the scope of technical compatibility.

[0041] The CPU 71 may set the lower limit rotation speed NeThB in accordance with the discharge control power limit Wout at the start of the fuel cut process. When a request for regeneration of the GPF 28 is made, the CPU 71 may set the second rotation speed Ne2 to the lower limit rotation speed NeThB regardless of whether the discharge control limit power Wout is equal to or less than the threshold value WoutTh.

[0042] The vehicle to which the vehicle control device is applied may be a vehicle having a configuration different from that of the vehicle 10 shown in FIG. 1, as long as it is a vehicle equipped with an engine 20 and a motor generator connected to the crankshaft 22 in a state capable of transmitting power.

[0043] The control device 70 is not limited to a device that includes a CPU and ROM and executes software processing. In other words, the control device 70 may have any of the following configurations (a), (b), and (c):

[0044] (a) The control device 70 includes one or more processors that execute various processes according to a computer program. The processor includes a CPU and memory such as RAM and ROM. The memory stores program code or instructions that cause the CPU to execute processes. Memory, i.e., computer-readable media, includes any available media that can be accessed by a general-purpose or special-purpose computer.

[0045] (b) The control device 70 includes one or more dedicated hardware circuits that perform various processes. Examples of dedicated hardware circuits include application-specific integrated circuits (ASICs) or FPGAs. ASIC stands for "Application Specific Integrated Circuit," and FPGA stands for "Field Programmable Gate Array."

[0046] (c) The control device 70 includes one or more processors that execute some of the various processes in accordance with a computer program, and one or more dedicated hardware circuits that execute the remaining processes among the various processes. [Explanation of symbols]

[0047] 10...vehicle, 13...accelerator pedal, 20...engine, 21...cylinder, 22...crankshaft, 26...exhaust passage, 28...GPF, 31, 32...MG, 34...battery, 70...control device, 71...CPU

Claims

1. The present invention is applied to a vehicle including an engine having an exhaust passage provided with a filter for capturing particulate matter contained in the exhaust, and a motor generator connected to a crankshaft of the engine in a state capable of transmitting power, a processing circuit; The processing circuitry When an accelerator pedal is operated and the engine is operated under load, the engine and the motor generator are driven so that the engine rotation speed does not fall below a lower limit rotation speed; When a regeneration request that is a request to regenerate the filter is issued, the lower limit rotation speed is increased compared to when the regeneration request is not issued, When the accelerator pedal is released while the engine is operating under load, a fuel cut process is initiated to stop the supply of fuel to the cylinders of the engine; When the fuel cut process is executed under the condition that the regeneration request is issued, a motoring process is started to suppress a decrease in the engine rotation speed by driving the motor generator. When the engine rotation speed reaches a minimum rotation speed while the fuel cut processing and the motoring processing are being performed, the motoring processing is terminated, and the fuel cut processing is terminated to resume fuel supply to the cylinders. Vehicle control device.

2. When the regeneration request is issued, if the discharge control limit power of the battery that stores the power supplied to the motor generator is less than a threshold, the processing circuit increases the lower limit rotation speed compared to when the regeneration request is not issued. The vehicle control device according to claim 1 .

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