Dual-motor electric drive system and control method

Abstract

The invention relates to the technical field of new energy automobiles, in particular to a dual-motor electric drive system and a control method.The dual-motor electric drive system comprises a main drive motor, an auxiliary drive motor, an engine and a differential mechanism, and the two sides of the differential mechanism are connected with wheels through a first transmission shaft and a second transmission shaft respectively; the differential mechanism is located between the main drive motor and the auxiliary drive motor, a first output shaft of the main drive motor and the first transmission shaft are coaxially arranged, and a second output shaft of the auxiliary drive motor and the second transmission shaft are coaxially arranged. A second clutch is arranged between the engine and the auxiliary drive motor and used for disconnecting or connecting transmission between the engine and the auxiliary drive motor. Therefore, the differential mechanism is located between the main drive motor and the auxiliary drive motor, that is, the two motors are symmetrically arranged and coaxially arranged in a matched mode, the space proportion is reduced, the space utilization rate is improved, meanwhile, the engine and the auxiliary drive motor are separated through the second clutch, the auxiliary drive motor can be independently operated, and electricity waste is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of new energy vehicles, and in particular to a dual-motor electric drive system and a control method. Background Art

[0002] New energy vehicles have built-in electric drive systems, and the electric drive systems include motors and transmission mechanisms, and the electric drive systems are used to drive wheels. In existing electric drive systems, the main drive motor and the auxiliary drive motor are generally located on the same side, while the other side is relatively empty, so the space utilization rate is low, and the output shaft of the motor and the input shaft of the wheel are set separately, that is, different shaft settings, so the number of shafts is relatively large, so the space occupied will be relatively large. At the same time, the engine generally runs synchronously with the auxiliary drive motor, but there is a time when the auxiliary drive motor needs to run and the engine is not running. At this time, the operation of the engine is a waste of electricity. Summary of the invention

[0003] The purpose of the present invention is to provide a dual-motor electric drive system and control method, in which the differential is located between the main drive motor and the auxiliary drive motor, that is, the dual motors are symmetrically arranged and coaxially arranged, thereby reducing the space occupancy and improving the space utilization rate. At the same time, through the setting of clutch 2, the engine and the auxiliary drive motor are separated, and the auxiliary drive motor can be operated independently and the power waste is reduced, thereby solving the existing problems of large space occupancy and low space utilization rate and the problem of power waste caused by synchronous operation of the engine and the auxiliary drive motor.

[0004] The object of the present invention is achieved in that:

[0005] A dual-motor electric drive system includes a main drive motor, an auxiliary drive motor, an engine and a differential, wherein a first transmission shaft and a second transmission shaft are respectively arranged on both sides of the differential, and the other ends of the first transmission shaft and the second transmission shaft are connected to wheels;

[0006] The differential is located between the main drive motor and the auxiliary drive motor, and the main drive motor is connected to one side of the differential through a transmission assembly 1, and the output shaft 1 of the main drive motor is coaxially arranged with the transmission shaft, and the auxiliary drive motor is connected to the other side of the differential through a transmission assembly 2, and the output shaft 2 of the auxiliary drive motor is coaxially arranged with the transmission shaft 2;

[0007] The transmission component 2 includes a clutch 1, and the clutch 1 is located between the differential and the auxiliary drive motor and is used to disconnect or connect the transmission between the differential and the auxiliary drive motor, and a clutch 2 is arranged between the engine and the auxiliary drive motor, and the clutch 2 is used to disconnect or connect the transmission between the engine and the auxiliary drive motor.

[0008] Preferably, the two ends of the clutch are respectively connected to the engine and the auxiliary drive motor through a gear set.

[0009] Preferably, the transmission assembly 1 includes a gear set, and the main drive motor is connected to the differential through the gear set;

[0010] Or / and, one end of the clutch is connected to the differential and the auxiliary drive motor respectively through a gear set.

[0011] Preferably, a clutch wear life prediction system is also included, and the system comprises:

[0012] A displacement sensor is installed on the release bearing of the clutch 1 and obtains the initial OFFSET value F0 of the clutch 1 and the current OFFSET value F after the clutch 1 is fully engaged each time;

[0013] The control module is used to calculate the degree of wear of the clutch 1 according to the initial OFFSET value F0 and the current OFFSET value F. When the degree of wear of the clutch 1 is greater than the set value K, the clutch 1 needs to be replaced, otherwise the clutch 1 does not need to be replaced.

[0014] Preferably, the control module is also used to read the flywheel torque N1 output by the engine and the engine speed, and calculate the current transmission torque N2 of the second clutch according to the flywheel torque N1 and the engine speed.

[0015] A control method for an electric drive system according to any of the above claims, based on real-time vehicle condition information, the vehicle controller calculates and determines the most suitable working mode, and outputs instructions to the electric drive system to optimize the coupling working condition, the working modes including: pure electric single motor working mode, pure electric generator working mode and pure electric dual motor working mode.

[0016] Preferably, the vehicle condition information includes the target torque required for vehicle driving, the maximum torque output by the main drive motor, the real-time SOC value of the battery and the target SOC value of the battery;

[0017] When the target torque required for vehicle driving is less than the maximum torque output by the main drive motor, and the real-time SOC value of the battery is greater than the target SOC value of the battery, the working mode is in the pure electric single motor working mode;

[0018] When the target torque required for vehicle driving is less than the maximum torque output by the main drive motor, and the real-time SOC value of the battery is less than the target SOC value of the battery, the working mode is in the pure electric generator working mode;

[0019] When the target torque required for vehicle driving is greater than the maximum torque output by the main drive motor, and the real-time SOC value of the battery is greater than the target SOC value of the battery, the working mode is in the pure electric dual-motor working mode.

[0020] Preferably, in the pure electric single motor operating mode, clutch one and clutch two are both in the disconnected state. At this time, the main drive motor serves as the power source and transmits power to the wheels through transmission component one, differential and drive shaft one, and the auxiliary drive motor and the engine are not working.

[0021] Preferably, in the pure electric generator working mode, the clutch 1 is in the disconnected state, and the clutch 2 is in the closed state. At this time, the main drive motor serves as the power source and transmits the power to the wheels through the transmission assembly 1, the differential and the drive shaft 1. At the same time, the engine works and transmits the power to the auxiliary drive motor, and the auxiliary drive motor serves as a generator and charges the battery.

[0022] When the battery is charged to a value where the real-time SOC of the battery is greater than the target SOC of the battery, clutch 2 is disconnected and the engine stops working, thus returning to the pure electric single-motor mode.

[0023] Preferably, in the pure electric dual-motor working mode, the clutch 1 is in a closed state, and the clutch 2 is in a disconnected state. At this time, the main drive motor and the auxiliary drive motor are used as a power source to transmit power to the wheels. At the same time, the engine does not work, and the auxiliary drive motor is used as a drive motor, and the battery is used to power the auxiliary drive motor;

[0024] When the battery is consumed to the point where the real-time SOC value of the battery is less than the target SOC value of the battery, the pure electric dual-motor working mode cannot be started, causing the vehicle to be torque-limited and unable to accelerate further. The target torque required for driving the vehicle is less than the maximum torque output by the main drive motor. At this time, clutch one is disconnected and clutch two is closed, thus entering the pure electric generator working mode, and allowing the engine to work to charge the auxiliary drive motor until the real-time SOC value of the battery is greater than the target SOC value of the battery, at which time the pure electric dual-motor mode can be started.

[0025] Compared with the prior art, the present invention has the following outstanding and beneficial technical effects:

[0026] The present invention locates the differential between the main drive motor and the auxiliary drive motor, that is, the dual motors are symmetrically arranged and coaxially arranged. Specifically, the output shaft 1 of the main drive motor is coaxially arranged with the transmission shaft, and the output shaft 2 of the auxiliary drive motor is coaxially arranged with the transmission shaft 2, thereby reducing the space occupation and improving the space utilization rate. At the same time, through the setting of the clutch 2, the engine and the auxiliary drive motor are separated, so that the auxiliary drive motor can be operated independently and the waste of electricity can be reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a structural schematic diagram of the present invention.

[0028] Figure 2 This is a structural schematic diagram of the pure electric single motor working mode.

[0029] Figure 3 This is a structural diagram of the pure electric generator working mode.

[0030] Figure 4 This is a structural diagram of the pure electric dual-motor working mode.

[0031] Reference numerals: 1-main drive motor; 11-output shaft 1; 2-auxiliary drive motor; 21-output shaft 2;

[0032] 3-engine; 4-differential; 5-drive shaft 1; 6-drive shaft 2; 7-wheel; 8-clutch 1;

[0033] 9-Clutch two. DETAILED DESCRIPTION

[0034] The specific implementation modes of the present invention are further described in detail below with reference to the accompanying drawings.

[0035] like Figure 1 As shown, a dual-motor electric drive system includes a main drive motor 1, an auxiliary drive motor 2, an engine 3 and a differential 4, and a transmission shaft 1 5 and a transmission shaft 2 6 are respectively arranged on both sides of the differential 4, and the other ends of the transmission shaft 1 5 and the transmission shaft 2 6 are connected to the wheels 7.

[0036] At the same time, the differential 4 is located between the main drive motor 1 and the auxiliary drive motor 2, and the main drive motor 1 is connected to one side of the differential 4 through a transmission component 1, and the output shaft 11 of the main drive motor 1 is coaxially arranged with the transmission shaft 1 5, and the auxiliary drive motor 2 is connected to the other side of the differential 4 through a transmission component 2, and the output shaft 2 21 of the auxiliary drive motor 2 is coaxially arranged with the transmission shaft 2 6.

[0037] Therefore, in actual use, the differential 4 is located between the main drive motor 1 and the auxiliary drive motor 2, that is, the dual motors are symmetrically arranged and coaxially arranged. Specifically, the output shaft 11 of the main drive motor 1 is coaxially arranged with the transmission shaft 1 5, and the output shaft 2 21 of the auxiliary drive motor 2 is coaxially arranged with the transmission shaft 2 6, thereby reducing the space occupancy and improving the space utilization.

[0038] Secondly, transmission component 2 includes clutch 1 8, and clutch 1 8 is located between the differential 4 and the auxiliary drive motor 2 and is used to disconnect or connect the transmission between the differential 4 and the auxiliary drive motor 2, and clutch 2 9 is arranged between the engine 3 and the auxiliary drive motor 2, and clutch 2 9 is used to disconnect or connect the transmission between the engine 3 and the auxiliary drive motor 2.

[0039] Therefore, in actual use, the engine 3 and the auxiliary drive motor 2 are separated by setting the clutch 2 9, so that the auxiliary drive motor 2 can be operated independently and the power waste can be reduced.

[0040] like Figure 1-Figure 4As shown, the two ends of the clutch 2 9 are connected to the engine 3 and the auxiliary drive motor 2 through a gear set. At the same time, the transmission component 1 includes a gear set, and the main drive motor 1 is connected to the differential 4 through a gear set, and the two ends of the clutch 1 8 are connected to the differential 4 and the auxiliary drive motor 2 through a gear set.

[0041] At the same time, in order to facilitate the replacement and maintenance of the clutch, the present invention also includes a clutch wear life prediction system, which includes a displacement sensor and a control module. The displacement sensor is used to be installed on the release bearing of the clutch 8, and obtain the initial OFFSET value F0 of the clutch 8 and the current OFFSET value F after each clutch 8 is fully engaged, and the OFFSET value in mechanics usually refers to the offset.

[0042] Moreover, the control module is used to calculate the degree of wear of the clutch 8 according to the initial OFFSET value F0 and the current OFFSET value F. When the degree of wear of the clutch 8 is greater than the set value K, the clutch 8 needs to be replaced, otherwise the clutch 8 does not need to be replaced.

[0043] The degree of wear of the clutch 8 = (F0-F) / Fa, and Fa is the wear thickness of the clutch 8. Specifically, the driven plate of the clutch 8 usually has an allowable wear thickness.

[0044] Secondly, clutch 2 9 can also be detected in the same way as clutch 1 8, and can also be detected in combination with engine 3. First, the control module is also used to read the flywheel torque N1 output by engine 3 and the speed of engine 3, and calculate the current transmission torque N2 of clutch 2 9 based on the flywheel torque N1 and the speed of engine 3.

[0045] This is because as the use time increases, the wear also increases, and the transmission torque N2 of the clutch 2 9 will decrease. When it decreases to the set value, it can be replaced. At the same time, the calculation formula is N2 = N1-(a×I), where a is used to represent the acceleration of the engine speed, and acceleration = (speed 2-speed 1) / time interval, and I is used to represent the engine's rotational inertia, and the engine's rotational inertia is an engine constant.

[0046] The present invention also protects a control method, and the control method is based on the electric drive system described in any of the above claims, specifically: based on real-time vehicle condition information, the vehicle controller calculates and determines the most suitable working mode, and outputs instructions to the electric drive system to make the coupling working condition reach the best, the working mode includes: pure electric single motor working mode, pure electric generator working mode and pure electric dual motor working mode.

[0047] The vehicle condition information includes the target torque required for vehicle driving, the maximum torque output by the main drive motor, the real-time SOC value of the battery, and the target SOC value of the battery. Therefore, when the target torque required for vehicle driving is less than the maximum torque output by the main drive motor, and the real-time SOC value of the battery is greater than the target SOC value of the battery, the working mode is in the pure electric single motor working mode;

[0048] Moreover, when the target torque required for vehicle driving is less than the maximum torque output by the main drive motor, and the real-time SOC value of the battery is less than the target SOC value of the battery, the working mode is in the pure electric generator working mode;

[0049] Secondly, when the target torque required for vehicle driving is greater than the maximum torque output by the main drive motor, and the real-time SOC value of the battery is greater than the target SOC value of the battery, the working mode is in the pure electric dual-motor working mode.

[0050] like Figure 2 As shown, in the pure electric single motor working mode, clutch 1 8 and clutch 2 9 are both in the disconnected state. At this time, the main drive motor 1 serves as the power source and transmits power to the wheel 7 through the transmission component 1, the differential 4 and the drive shaft 1 5, and the auxiliary drive motor 2 and the engine 3 are not working.

[0051] like Figure 3 As shown, in the pure electric generator working mode, clutch 1 8 is in a disconnected state and clutch 2 9 is in a closed state. At this time, the main drive motor 1 serves as a power source and transmits power to the wheel 7 through a transmission component, a differential 4 and a drive shaft 1 5. At the same time, the engine 3 works and transmits power to the auxiliary drive motor 2, and the auxiliary drive motor 2 is used as a generator to charge the battery.

[0052] When the battery is charged to a real-time SOC value greater than the target SOC value of the battery, the clutch 2 9 is disconnected and the engine 3 does not work, thereby returning to the pure electric single motor mode.

[0053] like Figure 4 As shown, in the pure electric dual-motor working mode, clutch 1 8 is in a closed state, and clutch 2 9 is in a disconnected state. At this time, the main drive motor and the auxiliary drive motor 2 act as a power source together to transmit power to the wheels 7. At the same time, the engine 3 does not work, and the auxiliary drive motor 2 is used as a drive motor, and the battery is used to power the auxiliary drive motor 2.

[0054] When the battery is consumed to the point where the real-time SOC value of the battery is less than the target SOC value of the battery, the pure electric dual-motor working mode cannot be started, so that the whole vehicle is torque-limited and cannot be accelerated further. The target torque required for vehicle driving is less than the maximum torque output by the main drive motor. At this time, clutch 1 8 is disconnected and clutch 2 9 is closed, thereby being in the pure electric generator working mode, and allowing the engine 3 to work and charge the auxiliary drive motor 2 until the real-time SOC value of the battery is greater than the target SOC value of the battery, at which time the pure electric dual-motor mode can be started.

[0055] The above shows and describes the basic principle and main features of the present invention and the advantages of the present invention. At the same time, the present invention is not limited by the above embodiments, so without departing from the principle and scope of the present invention, the present invention will also have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed for protection.

Claims

1. A dual-motor electric drive system, characterized in that: The vehicle comprises a main drive motor (1), an auxiliary drive motor (2), an engine (3) and a differential (4), wherein a transmission shaft (5) and a transmission shaft (6) are respectively arranged on both sides of the differential (4), and the other ends of the transmission shaft (5) and the transmission shaft (6) are connected to wheels (7); The differential (4) is located between the main drive motor (1) and the auxiliary drive motor (2), and the main drive motor (1) is connected to one side of the differential (4) through a transmission component 1, and an output shaft 1 (11) of the main drive motor (1) is coaxially arranged with a transmission shaft 1 (5), and the auxiliary drive motor (2) is connected to the other side of the differential (4) through a transmission component 2, and an output shaft 2 (21) of the auxiliary drive motor (2) is coaxially arranged with a transmission shaft 2 (6); The transmission assembly 2 comprises a clutch 1 (8), and the clutch 1 (8) is located between the differential (4) and the auxiliary drive motor (2) and is used to disconnect or connect the transmission between the differential (4) and the auxiliary drive motor (2), and a clutch 2 (9) is provided between the engine (3) and the auxiliary drive motor (2), and the clutch 2 (9) is used to disconnect or connect the transmission between the engine (3) and the auxiliary drive motor (2).

2. A dual-motor electric drive system according to claim 1, characterized in that: The two ends of the second clutch (9) are respectively connected to the engine (3) and the auxiliary drive motor (2) through a gear set.

3. The dual-motor electric drive system according to claim 1, characterized in that: The transmission assembly 1 comprises a gear set, and the main drive motor (1) is connected to the differential (4) via the gear set; Or / and, the two ends of the clutch one (8) are respectively connected to the differential (4) and the auxiliary drive motor (2) through a gear set.

4. A dual-motor electric drive system according to any one of claims 1 to 3, characterized in that: A clutch wear life prediction system is also included and includes: A displacement sensor is used to be installed on the release bearing of the clutch one (8) and obtain the initial OFFSET value F0 of the clutch one (8) and the current OFFSET value F after each clutch one (8) is fully engaged; The control module is used to calculate the degree of wear of the clutch one (8) according to the initial OFFSET value F0 and the current OFFSET value F. When the degree of wear of the clutch one (8) is greater than the set value K, the clutch one (8) needs to be replaced, otherwise the clutch one (8) does not need to be replaced.

5. A dual-motor electric drive system according to claim 4, characterized in that: The control module is also used to read the flywheel torque N1 output by the engine (3) and the engine (3) speed, and calculate the current transmission torque N2 of the second clutch (9) according to the flywheel torque N1 and the engine (3) speed.

6. A control method for an electric drive system according to any one of the above claims, characterized in that: Based on real-time vehicle condition information, the vehicle controller calculates and determines the most appropriate working mode, and outputs instructions to the electric drive system to achieve the best coupling working condition. The working modes include: pure electric single motor working mode, pure electric generator working mode and pure electric dual motor working mode.

7. A control method according to claim 6, characterized in that: The vehicle condition information includes the target torque required for vehicle driving, the maximum torque output by the main drive motor, the real-time SOC value of the battery, and the target SOC value of the battery; When the target torque required for vehicle driving is less than the maximum torque output by the main drive motor, and the real-time SOC value of the battery is greater than the target SOC value of the battery, the working mode is in the pure electric single motor working mode; When the target torque required for vehicle driving is less than the maximum torque output by the main drive motor, and the real-time SOC value of the battery is less than the target SOC value of the battery, the working mode is in the pure electric generator working mode; When the target torque required for vehicle driving is greater than the maximum torque output by the main drive motor, and the real-time SOC value of the battery is greater than the target SOC value of the battery, the working mode is in the pure electric dual-motor working mode.

8. A control method according to claim 6, characterized in that: In the pure electric single motor working mode, the clutch 1 (8) and the clutch 2 (9) are both in the disconnected state. At this time, the main drive motor (1) serves as the power source and transmits power to the wheels (7) through the transmission component 1, the differential (4) and the transmission shaft 1 (5), and the auxiliary drive motor (2) and the engine (3) are both not working.

9. A control method according to claim 6, characterized in that: In the pure electric generator working mode, the clutch 1 (8) is in the disconnected state and the clutch 2 (9) is in the closed state. At this time, the main drive motor (1) serves as the power source and transmits the power to the wheels (7) through the transmission component a differential (4) and the transmission shaft 1 (5). At the same time, the engine (3) works and transmits the power to the auxiliary drive motor (2). The auxiliary drive motor (2) is used as a generator and charges the battery. When the battery is charged to a battery real-time SOC value greater than the battery target SOC value, the second clutch (9) is disconnected and the engine (3) stops working, thereby returning to the pure electric single motor mode.

10. A control method according to claim 6, characterized in that: In the pure electric dual-motor working mode, the clutch 1 (8) is in a closed state, and the clutch 2 (9) is in a disconnected state. At this time, the main drive motor and the auxiliary drive motor (2) together serve as a power source to transmit power to the wheels (7). At the same time, the engine (3) does not work, and the auxiliary drive motor (2) is used as a drive motor, and the battery is used to power the auxiliary drive motor (2); When the battery is depleted to the point where the real-time SOC value of the battery is less than the target SOC value of the battery, the pure electric dual-motor working mode cannot be started, so that the whole vehicle is torque-limited and cannot be further accelerated. When the target torque required for vehicle driving is less than the maximum torque output by the main drive motor, the clutch 1 (8) is disconnected and the clutch 2 (9) is closed, thereby being in the pure electric generator working mode, and the engine (3) is operated to charge the auxiliary drive motor (2) until the real-time SOC value of the battery is greater than the target SOC value of the battery, at which time the pure electric dual-motor mode can be started.

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