Hybrid vehicles

Abstract

To provide a hybrid vehicle capable of appropriately charging a battery by regenerative generation.SOLUTION: A vehicle 1 is enabled to switch between a regenerative braking mode where a driving battery 11 is charged through generation by a travel-driving front motor 4 when traveling in deceleration and a motoring mode where motoring is performed in which an engine 2 is forcibly driven by driving a motor-generator 9 in a case where a charge ratio SOC of the driving battery 11 is equal to or higher than a predetermined value in a regenerative braking mode. In the vehicle, in the motoring mode, a water pump 30 for circulating a coolant in the engine 2 is caused to drive, with an output of the water pump 30 controlled on the basis of a temperature of the coolant.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a control technology during regenerative braking of a hybrid vehicle.

Background Art

[0002] In hybrid vehicles developed in recent years, there is known a vehicle including an engine (internal combustion engine), a generator driven by the internal combustion engine to generate electricity, a driving battery (storage battery) that can be charged by receiving power from the generator, and a driving motor that drives the driving wheels for running by receiving power from the driving battery or the generator. In the hybrid vehicle as described above, the electric power generated by the generator is supplied to the driving battery or the driving motor. Also, during vehicle deceleration, regenerative power generation is performed by the driving motor, and the generated electric power can be supplied to the driving battery for charging. By performing regenerative power generation, a braking force is applied by the driving motor (regenerative braking).

[0003] As described in Patent Document 1, when the driving battery is near full charge during regenerative braking, the electric power generated by the driving motor cannot be charged to the driving battery. Therefore, there is known a technique that enables regenerative braking by performing motoring in which, for example, the engine is driven by a generator to consume electric power. Also, Patent Document 1 discloses that when motoring is performed near full charge of the driving battery and sufficient electric power cannot be consumed by motoring, the electric power consumption is increased by operating the electric water pump of the engine together with motoring, thereby enabling regenerative braking.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, operating the electric water pump generates noise, so it is not advisable to operate it more than necessary. Furthermore, excessive operation of the electric pump may lead to overcooling of the internal combustion engine. The present invention was made to solve the above-mentioned problems, and its objective is to provide a hybrid vehicle that ensures regenerative braking force and appropriately operates the electric pump to suppress noise when motoring is performed when the battery is near full charge. [Means for solving the problem]

[0006] To achieve the above objectives, the present invention provides a hybrid vehicle comprising: an internal combustion engine mounted on the vehicle; a first electric motor capable of driving the internal combustion engine; a second electric motor capable of driving the vehicle and generating regenerative power during deceleration; a storage battery that supplies power to the second electric motor; an electric pump that circulates a refrigerant to the internal combustion engine; and a control unit that controls the first electric motor and the second electric motor, wherein the hybrid vehicle includes a refrigerant temperature detection unit that acquires the temperature of the refrigerant. The system includes an oil temperature detection unit that acquires the oil temperature of the internal combustion engine, The control unit is equipped with a regenerative braking mode in which the vehicle is decelerated by regenerating power with the second electric motor and charging the battery, and a motoring mode in which, when the charge level of the battery is above a predetermined value in the regenerative braking mode, motoring is performed by driving the first electric motor to forcibly drive the internal combustion engine and consume the power regenerated by the second electric motor, and in the motoring mode, the electric pump is driven and the temperature of the refrigerant is controlled. , and the difference between the oil temperature and the refrigerant temperature The output of the electric pump is controlled based on the following:

[0007] This allows the electric pump to be driven and consume power during motoring mode, increasing the amount of power that can be regenerated by the second electric motor even when the battery charge level is above a predetermined value, thereby ensuring regenerative braking force. Furthermore, since the output of the electric pump is controlled based on the refrigerant temperature, it is possible to suppress noise caused by excessive operation of the electric pump and prevent overcooling of the internal combustion engine.

[0008] Also, By understanding the condition of the internal combustion engine based on both its oil temperature and water temperature, the operating state of the electric pump can be made more appropriate. Preferably, the output of the electric pump is controlled according to the rotational speed of the motor ring, and the control unit corrects the output of the electric pump, which is determined according to the rotational speed of the motor ring, when the difference between the oil temperature and the refrigerant temperature is greater than or equal to a predetermined temperature difference, and controls the output of the electric pump, which is determined according to the rotational speed of the motor ring, when the difference between the oil temperature and the refrigerant temperature is less than the predetermined temperature difference.

[0009] This allows the system to control the state of the internal combustion engine by increasing the output of the electric pump, which is determined according to the motoring rotation speed, when the temperature difference between the oil temperature and the refrigerant temperature exceeds a predetermined temperature difference during motoring, thereby promoting heat exchange between the refrigerant and the lubricating oil. Preferably, the control unit controls the output of the electric pump based on the rotational speed of the motor ring and the temperature of the refrigerant when the rotational speed of the motor ring is above a predetermined speed, and controls the output of the electric pump based on the rotational speed of the motor ring when the rotational speed of the motor ring is below the predetermined speed.

[0010] As a result, when the motoring rotation speed exceeds a predetermined speed, the temperature of the internal combustion engine tends to rise. Therefore, by controlling the output of the electric pump based on the motoring rotation speed and the refrigerant temperature, it is possible to suppress an excessive rise in the internal combustion engine temperature. Preferably, the internal combustion engine and the electric pump are connected, and the electric pump has a refrigerant passage through which the refrigerant flows, and a bypass passage that bypasses the internal combustion engine is connected to the refrigerant passage, and the control unit drives the electric pump and controls the refrigerant to flow through the bypass passage when the temperature of the refrigerant is below a predetermined temperature during the motoring mode.

[0011] This allows the system to control the flow of the refrigerant through a bypass passage when the refrigerant temperature is below a predetermined temperature during motoring mode, thereby suppressing the temperature drop of the internal combustion engine. Preferably, the system includes a cooling device powered by electricity from the battery and used to cool the battery, and the control unit may increase the output of the cooling device when there is a surplus of power generated by regenerative power even after driving the motor and the electric pump.

[0012] This allows for increased power consumption by increasing the output of the cooling system when the regenerative power cannot be fully consumed by the motor and electric pump drive, thereby ensuring regenerative braking force. [Effects of the Invention]

[0013] According to the hybrid vehicle of the present invention, in motoring mode, power is consumed by driving an electric pump, which increases regenerative power and ensures a large amount of regenerative braking force. Furthermore, the electric pump is controlled by the refrigerant temperature , and the difference between the oil temperature and the refrigerant temperature By controlling the output based on this, the electric pump can be operated appropriately in response to changes in friction caused by temperature changes in the internal combustion engine during motoring, thereby reducing noise from the operation of the electric pump and suppressing overcooling of the internal combustion engine. [Brief explanation of the drawing]

[0014] [Figure 1] This is a schematic diagram of a hybrid vehicle according to one embodiment of the present invention. [Figure 2] This is a diagram showing the configuration of the regenerative control device in the hybrid vehicle of this embodiment.

Best Mode for Carrying Out the Invention

[0015] Hereinafter, embodiments of the hybrid vehicle of the present invention will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram of a driving system of a hybrid vehicle (hereinafter referred to as vehicle 1) according to an embodiment of the present invention. Vehicle 1 in an embodiment of the present invention is a vehicle such as a plug-in hybrid vehicle or a hybrid vehicle that drives a motor generator 9 (electric motor) by the output of an engine 2 (internal combustion engine) to generate electricity and includes an electric front motor 4 (second electric motor) that drives wheels.

[0016] The engine 2 can drive the drive shaft 8 of the front wheels 3 via the front transaxle 7 and can drive the motor generator 9 (first electric motor) via the front transaxle 7 to generate electricity. Further, the engine 2 and the front wheels 3 are connected via a clutch 16 disposed in the front transaxle 7. The front motor 4 is driven by being supplied with electric power from a drive battery 11 (storage battery) or the motor generator 9 mounted on the vehicle 1 via a control unit 20, and drives the drive shaft 8 of the front wheels 3 via the front transaxle 7.

[0017] The electric power generated by the motor generator 9 can charge the drive battery 11 and can supply electric power to the front motor 4. The drive battery 11 is composed of a secondary battery such as a lithium-ion battery. Further, the drive battery 11 is provided with a charge rate detection unit 11a (charge amount detection unit) that detects the charge rate (SOC) of the drive battery 11.

[0018] The control unit 20 has functions to control the driving mode, the output of the front motor 4, the power generation amount and output of the motor generator 9, the fuel injection amount and fuel injection timing in the engine 2, the engagement and disengagement of the clutch 16 in the front transaxle 7, etc. The driving modes include an EV driving mode, an engine driving mode, a parallel driving mode, and a series driving mode.

[0019] The control unit 20 is a control device for performing comprehensive control of the vehicle 1. The control unit 20 includes an input / output device, a storage device (ROM, RAM, non-volatile RAM, etc.), a central processing unit (CPU), a timer, etc. In the EV mode, the engine 2 is stopped and the motor 46 is driven to make the vehicle run. In the series mode, the clutch 16 of the front transaxle 7 is disengaged, the engine 2 drives the motor generator 9 to generate electricity, and at the same time, the front motor 4 is driven to make the vehicle run. In the series mode, the rotational speed of the engine 2 is set to an efficient value.

[0020] In the parallel mode, the clutch 16 of the front transaxle 7 is engaged, and the power of the engine 2 and the front motor 4 is transmitted to drive the front wheels 3. The control unit 20 sets the driving mode to the parallel mode in the efficient region of the engine 2, such as in the high-speed region. Also, in the region excluding the parallel mode, that is, in the medium and low-speed regions, it switches between the EV mode and the series mode based on the state of charge (SOC) of the drive battery 11.

[0021] In addition, the control unit 20 enables a regenerative braking mode in which when the vehicle is decelerating, the front motor 4 is forced to drive by the rotational force of the front wheels 3 to generate electricity (regenerative power generation), and at the same time, regenerative braking is executed to apply a braking force to the front wheels 3. The regenerative braking force in the regenerative braking mode can be changed by the selection operation of the shift lever.

[0022] Furthermore, in the regenerative braking mode during vehicle deceleration, the control unit 20 is capable of a motoring mode in which, for example, when the charge level of the drive battery 11 reaches or exceeds a threshold (predetermined value) near full charge, power is supplied to the motor generator 9 to activate it and rotate the engine 2. In the motoring mode, fuel injection to the engine 2 is suppressed, similar to the regenerative power generation mode, but motoring may be performed while fuel injection and ignition are still being carried out.

[0023] In motoring mode, with engine output suppressed by reducing fuel injection, power is consumed by driving the engine 2 with the motor generator 9. This ensures regenerative braking force even when the drive battery 11 is near full charge. The amount of power consumed by the motor generator 9 varies depending on the friction of the engine 2.

[0024] In motoring mode, the control unit 20 controls the motor generator 9 according to the charge level (charge rate) of the drive battery 11 and the amount of regenerative power generated by the front motor 4 to control the engine rotation speed (motoring speed) due to motoring. For example, the amount of regenerative power generated by the front motor 4 can be input from the control unit 20.

[0025] Figure 2 is a diagram showing the configuration of the regenerative braking control device in the vehicle of this embodiment. As shown in Figure 2, the control unit 20 receives the engine coolant temperature (engine water temperature) from the coolant temperature sensor 25 (refrigerant temperature detection unit) and the engine lubrication oil temperature (engine oil temperature) from the oil temperature sensor 26 (oil temperature detection unit) provided in the engine 2, as well as the engine rotational speed (motorizing speed during motoring), and controls the operation of the water pump 30, the coolant passage switching valve 31, and the battery cooling device 37. The engine rotational speed can be obtained from the engine rotational speed sensor 27 or from the rotational speed of the motor generator 9 during motoring.

[0026] The water pump 30 is an electric pump located in the coolant circulation path 35 (refrigerant passage) through which the coolant of the engine 2 flows, and is capable of circulating coolant in the coolant circulation path 35. The coolant circulation path 35 is equipped with a bypass passage 36 that bypasses the engine 2. The cooling water passage switching valve 31 is located at the upstream branching point between the cooling water circulation passage 35 and the bypass passage 36, and switches whether the cooling water discharged from the water pump 30 flows into either the engine 2 or the bypass passage 36.

[0027] The battery cooling device 37 (cooling device) is an electric device for cooling the drive battery 11, such as an electric fan. The specific operational control of the water pump 30, the cooling water channel switching valve 31, and the battery cooling device 37 during motoring mode is described below. The control unit 20 operates the water pump 30 when the engine water temperature is higher than a predetermined temperature T1, which is set appropriately, during motoring, and suppresses the operation of the water pump 30 when the engine water temperature is below the predetermined temperature T1. The predetermined temperature T1 can be set, for example, to around the temperature at which the engine 2 has finished warming up. As the engine temperature rises, the friction of the engine 2 decreases, so the power consumption of the motor generator 9 in motoring mode decreases. When the engine water temperature, which is related to the engine temperature, is above the predetermined temperature T1, that is, after the engine 2 has finished warming up, the friction of the engine 2 is increased by cooling the engine 2, and power is consumed by operating the water pump 30. This increases the regenerative power (power obtained by regenerative power generation) and ensures a high regenerative braking force.

[0028] Furthermore, when the engine water temperature is below the predetermined temperature T1, that is, before the engine 2 has finished warming up, even if the water pump 30 is stopped, the friction of the engine 2 is high and the power consumption of the motor generator 9 in motoring mode is sufficient, so a high regenerative braking force can be secured. In addition, by suppressing the operation of the water pump 30, the warm-up of the engine 2 can be accelerated and the noise caused by the operation of the water pump 30 can be reduced.

[0029] Furthermore, the control unit 20 controls the output of the water pump 30 to decrease as the engine water temperature rises during motoring. This allows the power consumption of the water pump 30 to be increased or decreased in accordance with the increase or decrease in friction of the engine 2, i.e., the increase or decrease in power consumption of the motor generator 9 in motoring mode, thereby ensuring regenerative braking force while reducing the noise of the water pump 30.

[0030] Furthermore, the control unit 20 should receive engine oil temperature along with engine water temperature as input and correct the output of the water pump 30 based on the temperature difference between the engine water temperature and the engine oil temperature in motoring mode. For example, if the temperature difference is greater than or equal to a predetermined temperature difference ΔT2, the output of the water pump 30 should be increased compared to when the temperature difference is less than the predetermined temperature difference ΔT2. When there is a difference between the engine water temperature and the engine oil temperature, the output of the water pump 30 can be increased to promote heat exchange between the engine water temperature and the engine oil temperature, thereby increasing the power consumption of the motor generator 9, increasing the regenerative power, and ensuring regenerative braking force.

[0031] Furthermore, the control unit 20 controls the output of the water pump 30 according to the motoring speed (rotational speed during motoring). When the temperature difference between the engine oil temperature and the engine water temperature is greater than or equal to a predetermined temperature difference, the control unit 20 corrects the output of the water pump 30 to increase the output determined according to the motoring speed. When the temperature difference is less than the predetermined temperature difference, the control unit 20 controls the output of the water pump 30 according to the output determined according to the motoring speed.

[0032] For example, as the motoring speed increases, the temperature of engine 2 may rise, so the output of water pump 30 should be increased. However, if the temperature difference between engine oil temperature and engine water temperature is less than a predetermined temperature difference, heat exchange cannot be expected between engine water temperature and engine oil temperature, so setting the output of water pump 30 to the value determined according to the motoring speed will sufficiently suppress an excessive temperature rise in engine 2.

[0033] Furthermore, the control unit 20 may control the water pump 30 based on the motoring speed and engine water temperature when the motoring speed is equal to or greater than a predetermined speed V1, and control the output of the water pump 30 based on the motoring speed when the motoring speed is less than the predetermined speed V1. When the motoring speed is above a predetermined speed, power consumption increases, and the difference in power consumption due to changes in engine water temperature becomes large. Therefore, by controlling the output of the water pump 30 based on the motoring speed and engine water temperature, the power consumption of the water pump 30 can be set with precision. When the motoring speed is below a predetermined speed, the power consumption of the motor generator 9 decreases, and the difference in power consumption due to changes in refrigerant temperature also decreases, so the output of the water pump 30 can be controlled with precision based on the motoring speed.

[0034] Furthermore, the cooling water circulation path 35 of the engine 2 is provided with a bypass passage 36 that bypasses the engine 2, and the control unit 20 should operate the water pump 30 and control the cooling water to flow through the bypass passage 36 when the engine water temperature is below a predetermined temperature during motoring mode. As a result, when the engine water temperature is below a predetermined temperature during motoring mode, the coolant is controlled to flow through the bypass passage 36, thereby suppressing the temperature drop of the engine 2 while increasing the power consumption of the water pump 30.

[0035] Furthermore, the vehicle 1 is equipped with a battery cooling device 37 that is powered by the drive battery 11 and cools the drive battery 11. The control unit 20 may increase the output of the battery cooling device 37 if the regenerative power cannot be fully consumed by the motoring and water pump 30, and the required regenerative braking force cannot be obtained, that is, if the regenerative power is greater than the power consumed by the motoring and water pump 30.

[0036] This allows for greater regenerative power generation and thus ensure regenerative braking force when the regenerative power cannot be fully consumed by motoring and driving the water pump 30. This is achieved by increasing the power consumption of the battery cooling device 37. Additionally, when regenerative power is used to charge the drive battery 11 during motoring, the drive battery 11 generates heat. Activating the battery cooling device 37 suppresses the temperature rise of the drive battery 11, thereby improving charging performance.

[0037] It should be noted that the present invention is not limited to the embodiments described above. For example, the detailed control described above may be modified as appropriate. This invention can be widely applied to hybrid vehicles capable of regenerative power generation and motoring. [Explanation of Symbols]

[0038] 1 vehicle 2. Engine (internal combustion engine) 4. Front motor (second electric motor) 9. Motor Generator (First Electric Motor) 11. Power battery (rechargeable battery) 11a Charge level detection unit (charge amount detection unit) 20 Control Unit (Control Section) 25 Cooling water temperature sensor (refrigerant temperature detection unit) 26. Oil temperature sensor (oil temperature detection unit) 30 Water pump (electric pump) 35 Cooling water circulation path (refrigerant path) 36 Bypass passage 37. Battery cooling system (cooling device)

Claims

1. A hybrid vehicle comprising: an internal combustion engine mounted on the vehicle; a first electric motor capable of driving the internal combustion engine; a second electric motor capable of driving the vehicle and generating regenerative power during deceleration; a storage battery that supplies power to the second electric motor; an electric pump that circulates a refrigerant to the internal combustion engine; and a control unit that controls the first electric motor and the second electric motor, A refrigerant temperature detection unit that acquires the temperature of the refrigerant, The system includes an oil temperature detection unit that acquires the oil temperature of the internal combustion engine, The control unit, The vehicle can be switched between a regenerative braking mode, in which the vehicle is decelerated by regenerating power with the second electric motor and charging the battery, and a motoring mode, in which, when the battery charge level is above a predetermined value during the regenerative braking mode, the internal combustion engine is forcibly driven by the first electric motor to consume the power regenerated by the second electric motor. During the motoring mode, the electric pump is driven, and the output of the electric pump is controlled based on the temperature of the refrigerant and the difference between the oil temperature and the temperature of the refrigerant. A hybrid vehicle characterized by the following features.

2. The output of the electric pump is controlled according to the rotational speed of the motor ring. The control unit corrects the output of the electric pump, which is determined according to the rotational speed of the motor ring, when the difference between the oil temperature and the refrigerant temperature is greater than or equal to a predetermined temperature difference, and controls the output of the electric pump, which is determined according to the rotational speed of the motor ring, when the difference between the oil temperature and the refrigerant temperature is less than the predetermined temperature difference. The hybrid vehicle according to feature 1.

3. The control unit controls the output of the electric pump based on the rotation speed of the motor ring and the temperature of the refrigerant when the rotation speed of the motor ring is above a predetermined speed, and controls the output of the electric pump based on the rotation speed of the motor ring when the rotation speed of the motor ring is below the predetermined speed. The hybrid vehicle according to feature 1.

4. The internal combustion engine and the electric pump are connected, and the electric pump has a refrigerant passage through which the refrigerant flows. A bypass passage that bypasses the internal combustion engine is connected to the refrigerant passage. The hybrid vehicle according to claim 1, characterized in that the control unit drives the electric pump and controls the flow of the refrigerant through the bypass passage when the temperature of the refrigerant is below a predetermined temperature during the motoring mode.

5. It has a cooling device that is powered by electricity from the aforementioned battery and cools the aforementioned battery, The control unit increases the output of the cooling device when there is a surplus of power generated by regenerative power generation even after driving the motor and the electric pump. The hybrid vehicle according to feature 1.

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