Control system for hybrid vehicles

Abstract

This invention provides a control device for hybrid vehicles that suppresses the feeling of deceleration when the accelerator is released in parallel mode. [Solution] The control device for a hybrid vehicle has an internal combustion engine and a motor mounted on the vehicle, and has a parallel mode in which the internal combustion engine outputs power to the drive wheels, and a series mode in which the power generated by the internal combustion engine is output to the motor, and when the accelerator pedal is turned off during the parallel mode, the control device prohibits fuel cut control which interrupts fuel injection of the internal combustion engine while continuing the parallel mode.

Description

Technical Field

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

Background Art

[0002] Conventionally, a control device for a hybrid vehicle having a parallel mode is known (see, for example, Patent Document 1). Patent Document 1 discloses a control device for a hybrid vehicle having a parallel mode in which the front wheels of the vehicle are driven by an engine and a front motor. The control device for the hybrid vehicle of Patent Document 1 has fuel supply stop control for stopping the fuel supply to the engine when the vehicle decelerates (accelerator off). The control device for the hybrid vehicle of Patent Document 1 executes regenerative braking while continuing the fuel supply when the charge rate of the drive battery decreases in the parallel mode. The control device for the hybrid vehicle of Patent Document 1 charges the drive battery by driving the generator while continuing the operation of the engine in order to promote the charging of the drive battery.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the parallel mode, since the drive wheels (front wheels in Patent Document 1) are driven by the engine, a strong deceleration feeling occurs when fuel supply stop control (fuel cut control) is executed. Even in the control device for the hybrid vehicle of Patent Document 1, if the fuel supply stop control is executed during the parallel mode when the charge rate is not decreasing, a strong deceleration feeling occurs.

[0005] The objective of this disclosure is to provide a control device for a hybrid vehicle that suppresses the feeling of deceleration when the accelerator is released in parallel mode. [Means for solving the problem]

[0006] The control device for a hybrid vehicle according to this disclosure comprises an internal combustion engine mounted on the vehicle and a motor, and has a parallel mode in which the internal combustion engine outputs power to the drive wheels and a series mode in which the power generated by the internal combustion engine outputs power to the motor, wherein when the accelerator pedal is turned off during the parallel mode, fuel cut control, which interrupts fuel injection of the internal combustion engine, is prohibited while continuing the parallel mode. [Effects of the Invention]

[0007] According to the control system of this hybrid vehicle, by prohibiting fuel cut-off when the accelerator is released and parallel mode is maintained, engine braking caused by friction and pump losses in the internal combustion engine is suppressed. This reduces the feeling of deceleration caused by the transmission of engine braking to the drive wheels. [Brief explanation of the drawing]

[0008] [Figure 1] A system diagram of a control system for a hybrid vehicle according to one embodiment of the present disclosure. [Figure 2] A system diagram of an internal combustion engine according to one embodiment of the present disclosure. [Figure 3] A flowchart illustrating the control procedures performed by the control device of the hybrid vehicle of this disclosure. [Modes for carrying out the invention]

[0009] Hereinafter, one embodiment of this disclosure will be described with reference to the drawings.

[0010] As shown in Figures 1 and 2, the control system 1 of vehicle C includes an engine (an example of an internal combustion engine) 2, a motor (FrM) 3, a generator (GEN) 4, a drive battery (BT) 6, a transaxle 8, an inverter 12 that controls the motor 3 and generator 4, an accelerator pedal 14 operated by the user of vehicle C, a charger 16 that can be connected to an external power source, an external power supply device 18 that can supply power to external devices such as home appliances, a gradient sensor 20, a control device 22, and a fuel tank 24. Vehicle C in this embodiment is a plug-in hybrid electric vehicle (PHEV) equipped with external charging, which allows power from an external power source to be stored in the drive battery 6 by the charger 16, and external power supply, which allows power from the drive battery 6 to be supplied to external devices by the external power supply device 18.

[0011] As shown in Figure 1, the engine 2 is connected to the generator 4 and drives the generator 4. Furthermore, in this embodiment, the engine 2 can drive the wheels C1 via the transaxle 8. The engine 2 in this embodiment is a four-cylinder in-line gasoline engine.

[0012] As shown in Figure 2, the engine 2 has a fuel injector 40. The fuel injector 40 in this embodiment has an intake port injector 40a that injects fuel into the intake port 42 and an in-cylinder injector 40b that injects fuel into the cylinder N. The engine 2 receives fuel from the fuel tank 24 and consumes it by burning it.

[0013] As shown in Figure 1, the motor 3 is connected to the wheel C1 via the transaxle 8 and axle 10, and drives the wheel C1. The motor 3 in this embodiment is a three-phase AC motor having multiple coils and multiple permanent magnets. The motor 3 is also driven by the rotation of the axle 10 (wheel C1) to generate electricity (regenerative power). Therefore, the motor 3 is a motor-generator capable of both powering and generating electricity. The generator 4 is connected to the engine 2 and can drive the engine 2. The generator 4 motorizes the engine 2 while powering is supplied by the drive battery 6. On the other hand, the generator 4 is driven by the engine 2 to generate electricity while the engine 2 is running. Therefore, the generator 4 is a motor-generator capable of both powering and generating electricity.

[0014] The drive battery 6 outputs power to the motor 3 and generator 4, and also receives power generated by the motor 3 and generator 4. Furthermore, the drive battery 6 receives external power via the charger 16. In this embodiment, the drive battery 6 is composed of multiple lithium-ion batteries.

[0015] The transaxle 8 has multiple gears and a clutch 8a. The engine 2 is connected to the generator 4 and the axle 10 via the transaxle 8. When the clutch 8a is open, power transmission between the engine 2 and the axle 10 is interrupted, and when the clutch 8a is engaged, power from the engine 2 is transmitted to the axle 10.

[0016] The inverter 12 controls the motor torque of the motor 3 by converting the DC power supplied from the drive battery 6 into AC power and adjusting the power supplied to the motor 3. Furthermore, when the motor 3 is regenerating, the inverter 12 controls the regenerative torque of the motor 3 by converting the AC power supplied from the motor 3 into DC power and adjusting the power supplied to the drive battery 6.

[0017] The gradient sensor 20 detects the gradient state of the vehicle C in the longitudinal direction, that is, whether the vehicle C is tilted relative to the horizontal plane. In this embodiment, the gradient sensor 20 is a camera. The gradient sensor 20 is electrically connected to the control device 22.

[0018] The control device 22 is electrically connected to the engine 2 and the motor 3 via the inverter 12, and controls the engine 2 and the motor 3. The control device 22 is actually an ECU (Electronic Control Unit) composed of a microcomputer including an arithmetic unit, memory, and input / output buffers. The control device 26 controls the vehicle C based on maps and programs stored in memory.

[0019] Vehicle C in this embodiment has driving modes such as EV mode, series mode, and parallel mode. In EV mode, with the engine 2 stopped, vehicle C drives the motor 3 with power from the drive battery 6. In series mode, vehicle C disengages the clutch 8a, drives the generator 4 with the engine 2, and uses the power generated by the generator 4 to drive the motor 3 and drive the wheels (an example of drive wheels) C1. In parallel mode, vehicle C engages the clutch 8a and uses the power of the engine 2 to drive the wheels C1 via the axle 10. In vehicle C, the control device 22 switches between each driving mode according to the depression state of the accelerator pedal 14, and controls the motor 3 and generator 4 via the inverter 12, as well as the engine 2.

[0020] In addition, the vehicle C may also have an external power supply mode, a charging mode, and a save mode. In the external power supply mode, when the connector 18a is connected to an external device, the control device 26 supplies power from the drive battery 6 to the external device using the external power supply device 18. When the state of charge (SOC) of the drive battery 6 becomes lower than the minimum SOC during the external power supply mode, the control device 22 disconnects the clutch 8a, starts the engine 2 to drive the generator 4, stores the power generated by the generator 4 in the drive battery 6, and supplies it to the external device, thereby executing an engine power generation external power supply mode. In the charging mode, the control device 26 drives the generator 4 by the engine 2 and mainly stores the power generated by the generator 4 in the drive battery 6. In the save mode, the control device 22 restricts the output of the drive battery 6 so as to maintain the SOC of the drive battery 6. In the save mode, the power generated by the generator 4 is supplied to the motor 3. In this embodiment, in the save mode, the power performance of the vehicle C is suppressed more than in the series mode, and priority is given to maintaining the output of the drive battery 6.

[0021] The control device 22 includes a determination unit that determines whether the state of the vehicle C is in the first state or the second state. In the first state, when the accelerator pedal 14 is turned off during the parallel mode, the control device 22 disconnects the clutch 8a and switches to the series mode. In the second state, when the accelerator pedal is turned off during the parallel mode, the control device 22 maintains the connection state of the clutch 8a and continues the parallel mode. Details of the first state and the second state will be described later.

[0022] The control device 22 includes a gradient acquisition unit 22a. In this embodiment, the gradient acquisition unit 22a is a program stored in the memory of the control device 22. The gradient acquisition unit 22a determines the gradient situation of the vehicle C by performing image processing on the image acquired from the gradient sensor 20. In this embodiment, the control device 22 determines, as the gradient situation, whether the vehicle C is climbing an uphill, whether the vehicle C is descending a downhill, whether there is an uphill in front of the vehicle C (in the traveling direction), or whether there is a downhill.

[0023] The control device 22 includes an outside air temperature sensor 22b. In the present embodiment, the outside air temperature sensor 22b is disposed inside the control device 22. However, the outside air temperature sensor 22b may be disposed, for example, in the intake duct of the engine 2. In addition, the outside air temperature sensor 22b may be disposed at any location of the vehicle C.

[0024] The control device 22 is capable of executing fuel cut control. The fuel cut control is control for temporarily interrupting the injection from the fuel injector 40.

[0025] Next, the control procedure executed by the control device 22 will be described using the flowchart of FIG. 3.

[0026] In step S1, the control device 22 determines whether it is in the parallel mode. In the present embodiment, the control device 22 determines that it is in the parallel mode when the conditions for the parallel mode stored in the memory in advance are satisfied. The conditions for the parallel mode are conditions under which it is more efficient to transmit power from the engine 2 to the wheels C1 than in the series mode. The conditions are, for example, that the speed V of the vehicle C is a predetermined speed or higher (for example, 6 km / h or higher), or that the required output Q calculated from the depression amount of the accelerator pedal 14 is constant. The control device 22 may determine that it is in the parallel mode when the clutch 8a is in the connected state. When the control device 22 determines that it is in the parallel mode (step S1 YES), the process proceeds to step S2.

[0027] When the control device 22 determines that it is not in the parallel mode (step S1 NO), it returns.

[0028] In step S2, the control device 22 determines whether the accelerator pedal 14 has been turned off. In the present embodiment, the control device 22 determines that the accelerator pedal 14 has been turned off when the depression amount of the accelerator pedal 14 is zero. When the control device 22 determines that the accelerator pedal 14 has been turned off (step S2 YES), the process proceeds to step S3.

[0029] If the control device 22 determines that the accelerator pedal 14 is not turned off (step S2 NO), it returns to the starting position.

[0030] In step S3, the control device 22 determines whether the vehicle is in the second state. The second state is a cryogenic state where the temperature of the intake air drawn into the engine 2 is below the first temperature (e.g., below minus 10°C) or above the second temperature (e.g., above 40°C). In this embodiment, the second state is whether the vehicle C is located in an environmental region (state) where the ambient temperature T obtained from the ambient temperature sensor 22b is at a cryogenic temperature (e.g., below minus 10°C) or an extremely high temperature (e.g., above 40°C). At cryogenic and extremely high temperatures, it becomes difficult for the drive battery 6 to accept power from the regeneration of the motor 3. For this reason, in the second state, the parallel mode is continued in order to utilize engine braking. On the other hand, especially at cryogenic temperatures, the frictional resistance of the sliding parts of the engine 2 increases. For this reason, the deceleration due to engine braking when fuel cut control is performed increases. If the control device 22 determines that the vehicle is in the second state (step S3 YES), it proceeds to step S4.

[0031] In step S4, the control device 22 determines whether or not the vehicle is currently climbing an uphill slope. If the control device 22 determines that the vehicle is currently climbing an uphill slope (step S4 YES), it proceeds to step S5.

[0032] In step S5, the control device 22 prohibits fuel cut control. In this embodiment, fuel cut control is prohibited if the second state is in effect. However, the control device 22 may also prohibit fuel cut control when the temperature is extremely low. On uphill slopes, the deceleration of vehicle C due to fuel cut control is more pronounced. Therefore, at extremely low temperatures, the user of vehicle C is more likely to experience an excessive deceleration. The control device 22 returns after prohibiting fuel cut control.

[0033] If the control device 22 determines that it is not currently climbing an uphill slope (step S4 NO), it proceeds to step S6.

[0034] In step S6, the control device 22 determines whether or not the vehicle is currently descending a downhill slope (downward gradient).

[0035] If the control device 22 determines that the vehicle is descending a downhill slope (step S6 YES), it proceeds to step S10 and executes fuel cut control. If fuel cut control is not executed on a downhill slope, the vehicle C will continue to accelerate. Therefore, the control device 22 activates engine braking by executing fuel cut control.

[0036] If the control device 22 determines that it is not currently going downhill (downhill gradient) (step S6 NO), that is, if it determines that it is traveling on level ground, it proceeds to step S7.

[0037] In step S7, the control device 22 determines whether or not there is an uphill slope in the direction of travel of vehicle C. If the control device 22 determines that there is an uphill slope in the direction of travel of vehicle C (step S7 YES), it proceeds to step S8.

[0038] If the control device 22 determines that there is no uphill gradient in the direction of travel of vehicle C (step S7 NO), it returns.

[0039] In step S8, the control device 22 prohibits fuel cut control and increases the fuel injection amount or intake air amount to increase the torque of engine 2. When vehicle C enters a slope from flat ground while fuel cut is in effect, the deceleration of vehicle C increases. As a result, the user of vehicle C is likely to experience a strong feeling of deceleration. Therefore, the control device 22 suppresses the feeling of deceleration by prohibiting fuel cut control and increasing the torque of engine 2. The control device 22 may, for example, change the amount by which the torque is increased according to the gradient.

[0040] If the control device 22 determines that it is not in the second state (step S3 NO), it proceeds to step S9. In step S9, the control device 22 determines that it is in the first state and proceeds to step S10. That is, the first state is a state that is not the second state. In step S10, in the first state, the control device 22 switches to series mode, disengages the clutch 8a, and performs fuel cut control. In this state, it performs regenerative braking of the motor 3 equivalent to engine braking when the outside temperature is in the normal temperature range (for example, between -10°C and 40°C). The control device 22 charges the drive battery 6 with the power generated by regeneration. The control device 22 returns after performing fuel cut control.

[0041] As explained above, this disclosure provides a control device 22 for a hybrid vehicle C that suppresses the feeling of deceleration when the accelerator is released in parallel mode.

[0042] <Other Embodiments> Although embodiments of the present disclosure have been described above, the present disclosure is not limited to the embodiments described above, and various modifications are possible without departing from the spirit of the invention. In particular, the various modifications described herein can be combined as needed.

[0043] In the above embodiment, the fuel injection system 40 was described using an example that includes an intake port injection valve 40a for injecting fuel into the intake port 42 and an in-cylinder injection valve 40b for injecting fuel into the cylinder N, but the disclosure is not limited thereto. The engine 2 may be an engine 2 with only the intake port injection valve 40a, or an engine 2 with only the in-cylinder injection valve 40b. The engine 2 may also be a diesel engine.

[0044] In the above embodiment, the gradient sensor 20 was described using a camera as an example, but this disclosure is not limited thereto. The gradient sensor 20 may be, for example, an infrared radar, a millimeter-wave radar, or the like. The gradient acquisition unit 22a may determine the gradient in front of the vehicle C from the information acquired from these sensors. The control device 22 may also determine whether the vehicle C is currently going uphill or downhill using a G sensor (not shown) or a gyro sensor built into the control device 22.

[0045] In the above embodiment, the second state was described using an example where the ambient temperature T obtained from the ambient temperature sensor 22b is extremely low (e.g., below -10°C) or extremely high (e.g., above 40°C), but the disclosure is not limited thereto. For example, during parallel mode in charge mode, or during parallel mode in engine power generation external power supply mode, the second state may be even if the temperature is higher than extremely low (e.g., below 0°C). This allows the control device 22 to increase the frequency of prohibiting fuel cut control. As a result, the control device 22 can generate power while suppressing the feeling of deceleration when the accelerator is released. [Explanation of Symbols]

[0046] 2: Engine, 3: Motor, 4: Generator, 6: Drive battery, 8: Transaxle 14: Accelerator pedal, 16: Charger, 18: External power supply device 20: Gradient sensor, 22: Control device, 22a: Gradient acquisition unit, 26: Control device 40: Fuel injection system, 40a: Intake port injection valve, 40b: In-cylinder injection valve C: Hybrid vehicle (vehicle)

Claims

1. A control device for a hybrid vehicle having an internal combustion engine mounted on the vehicle and a motor, the control device having a parallel mode that outputs power from the internal combustion engine to the drive wheels and a series mode that outputs power generated by the internal combustion engine to the motor, If the accelerator pedal is released during the parallel mode, fuel cut control, which interrupts fuel injection of the internal combustion engine while continuing the parallel mode, is prohibited. Control system for hybrid vehicles.

2. When the vehicle is in the first state, if the accelerator pedal is turned off during the parallel mode, the system switches to the series mode. When the vehicle is in the second state, if the accelerator pedal is turned off during the parallel mode, the parallel mode is continued. Equipped with, During the second state, the fuel cut control is prohibited. A control device for a hybrid vehicle according to claim 1.

3. The vehicle further comprises a gradient acquisition unit that acquires the status of the vehicle being on a gradient. If an uphill gradient is obtained by the gradient acquisition unit during the second state, the fuel cut control is prohibited. A control device for a hybrid vehicle according to claim 2.

4. The second state is a state in which the intake air of the internal combustion engine is at an extremely low temperature or an extremely high temperature. A control device for a hybrid vehicle according to claim 2.

5. The vehicle further comprises a gradient acquisition unit that acquires the status of the vehicle being on a gradient. If a downward slope is obtained by the slope acquisition unit during the second state, the fuel cut control is executed. A control device for a hybrid vehicle according to any one of claims 2 to 4.

Images