Double-motor electric drive axle with torque control function and control method thereof

Abstract

The invention provides a double-motor electric drive axle with a torque control function and a control method thereof. The double-motor electric drive axle with the torque control function comprises a first motor, a second motor, a switching assembly, a first speed reduction assembly, a second speed reduction assembly, a differential mechanism and two output half shafts connected with the differential mechanism, the second speed reduction assembly comprises a brake, a first-stage speed reduction unit and a second-stage speed reduction unit, and the second-stage speed reduction unit is a planet row. The first motor is connected with a shell of the differential mechanism through the first speed reduction assembly, the second motor is connected with the first speed reduction assembly through the switching assembly or connected with a sun gear of the second-stage speed reduction unit through the switching assembly, and a planet carrier of the second-stage speed reduction unit is connected with one of the output half shafts. According to the double-motor electric drive axle with the torque control function and the control method of the double-motor electric drive axle, a novel scheme for actively distributing the drive torque between the left drive wheel and the right drive wheel according to needs is achieved.

Description

Technical Field

[0001] This invention relates to the field of electric drive axles, and more specifically to a dual-motor electric drive axle with torque control function and its control method. Background Technology

[0002] Vehicle dynamics control is one of the core technology areas of the modern automotive industry, aiming to improve vehicle handling, stability, and safety under various driving conditions. The differential, as a key component of the drive axle, primarily functions to allow a speed difference between the left and right drive wheels during cornering, ensuring smooth cornering. Traditional differentials, such as open differentials and limited-slip differentials, are passive devices. While they achieve basic differential functions, they cannot actively and precisely distribute torque between the left and right drive wheels according to driving intentions. This leads to instability phenomena such as understeer ("pushing") or oversteer ("fishtailing") under extreme conditions, such as high-speed cornering or low-traction surfaces, limiting the improvement of vehicle handling limits. To overcome these shortcomings, torque control technology has emerged. This technology can actively distribute drive torque between the left and right drive wheels as needed, thereby generating yaw moment that directly assists vehicle steering, significantly improving cornering performance and driving stability. This invention provides a new torque control scheme. Summary of the Invention

[0003] To achieve the function of actively distributing drive torque between the left and right drive wheels as needed, this invention provides a dual-motor electric drive bridge with torque control function and its control method.

[0004] A dual-motor electric drive axle with torque control function includes a first motor, a second motor, a switching assembly, a first reduction assembly, a second reduction assembly, a differential, and two output half-shafts connected to the differential. The second reduction assembly includes a brake, a primary reduction unit, and a secondary reduction unit. The secondary reduction unit is a planetary gear set. The first motor is connected to the housing of the differential through the first reduction assembly. The second motor is connected to the first reduction assembly through the switching assembly, or connected to the sun gear of the secondary reduction unit through the switching assembly. The planet carrier of the secondary reduction unit is connected to one of its output half-shafts. The ring gear of the secondary reduction unit is connected to the housing of the differential through the primary reduction unit. The brake is located on the axle housing and connected to the sun gear of the secondary reduction unit.

[0005] In a preferred embodiment of the dual-motor electric drive axle with torque control function provided by the present invention, the primary reduction unit is a planetary gear set, the ring gear of the primary reduction unit is connected to the ring gear of the secondary reduction unit, the planet carrier of the primary reduction unit is connected to the housing of the differential, and the sun gear of the primary reduction unit is fixedly connected to the axle housing. The primary reduction unit and the secondary reduction unit have the same number of teeth.

[0006] In a preferred embodiment of the dual-motor electric drive axle with torque control function provided by the present invention, the first reduction assembly is a three-stage parallel shaft reduction assembly. The first reduction assembly includes three stages of reduction gears and two parallel shafts. The first stage of reduction gears connects the output shaft of the first motor and the first parallel shaft, the second stage of reduction gears connects the first parallel shaft and the second parallel shaft, and the third stage of reduction gears connects the second parallel shaft and the housing of the differential; the second motor is connected to the first parallel shaft through the switching assembly.

[0007] In a preferred embodiment of the dual-motor electric drive axle with torque control function provided by the present invention, the switching component includes an input engagement tooth, a straight engagement tooth, a steering engagement tooth, and an engagement tooth sleeve. The input engagement tooth is connected to the output shaft of the second motor, the straight engagement tooth is connected to the first reduction assembly, the steering engagement tooth is connected to the sun gear of the secondary reduction unit, and the engagement tooth sleeve engages with the input engagement tooth and the straight engagement tooth, or engages with the input engagement tooth and the steering engagement tooth, or does not engage with either.

[0008] In a preferred embodiment of the dual-motor electric drive axle with torque control function provided by the present invention, a steering reduction gear set is further included, wherein the steering engagement gear is disposed on the steering reduction gear set and is connected to the sun gear of the secondary reduction unit through the steering reduction gear set.

[0009] In a preferred embodiment of the dual-motor electric drive axle with torque control function provided by the present invention, it includes single-motor straight-line driving, dual-motor straight-line driving, left-turn driving and right-turn driving states. In single-motor straight-line drive and dual-motor straight-line drive states, the brake is activated and the sun gear of the secondary reduction unit is fixed. In single-motor straight-line drive state, the engagement sleeve is isolated, the first motor drives the first reduction assembly, and the second motor stops. In dual-motor straight-line drive state, the engagement sleeve engages the input engagement tooth and the straight-line engagement tooth, and the first motor and the second motor jointly drive the first reduction assembly. In left-turn and right-turn driving states, the brake is closed and the sun gear of the secondary reduction unit is released. The engagement gear engages the input engagement gear and the steering engagement gear. The first motor drives the first reduction assembly, and the second motor drives the sun gear of the secondary reduction unit. In left-turn driving state, the second motor is in the opposite direction to the first motor. In right-turn driving state, the second motor is in the same direction as the first motor.

[0010] In left-turn drive mode, the rotational speed and torque of the left-side output half-shaft are both less than those of the right-side output half-shaft; in right-turn drive mode, the rotational speed and torque of the left-side output half-shaft are greater than those of the right-side output half-shaft.

[0011] A control method for a dual-motor electric drive axle is provided, which controls the dual-motor electric drive axle with torque control function to switch between four driving states: single-motor straight driving, dual-motor straight driving, left turn, and right turn; by controlling the speed of the second motor, the torque and speed difference between the two vehicles on both sides during steering is actively controlled.

[0012] Compared with existing technologies, the dual-motor electric drive bridge with torque control function and its control method provided by this invention have the following beneficial effects: 1. The electric drive axle provided by this invention, through the intervention of a second motor, achieves active control of the difference in speed and torque between the two wheels during cornering. This allows the outer wheel to obtain a higher speed and greater driving torque, generating a yaw moment that assists in vehicle steering. This greatly reduces understeer, making the vehicle more agile and stable when cornering.

[0013] 2. The electric drive axle provided by this invention can achieve mode switching through simple operation of the gear sleeve and brake, with rapid response and adaptability to various driving scenarios.

[0014] 3. The electric drive axle provided by this invention can be driven by a single motor for straight driving. In this case, the system degenerates into a highly efficient traditional differential, suitable for smooth daily driving with minimal energy loss. Alternatively, it can be driven by two motors for straight driving, providing peak power output to meet the needs of rapid acceleration, high-speed cruising, or heavy loads, offering strong power. It adapts to various driving scenarios. Attached Figure Description

[0015] Figure 1 This is a structural diagram of a dual-motor electric drive bridge with torque control function; Figure 2 It is a power flow diagram of a dual-motor electric drive bridge with torque control function in single-motor straight-drive mode; Figure 3 It is a power flow diagram of a dual-motor electric drive bridge with torque control function in the dual-motor straight-drive state; Figure 4 It is a power flow diagram of a dual-motor electric drive axle with torque control function in left-turn drive mode; Figure 5 This is a power flow diagram of a dual-motor electric drive bridge with torque control function in right-turn drive mode.

[0016] The diagram labels are as follows: 1. First motor; 2. Second motor; 3. First output shaft; 4. First parallel shaft; 5. Second parallel shaft; 6. Second output shaft; 7. Right half shaft; 8. Left half shaft; 9. First-stage driving gear; 10. First-stage driven gear; 11. Second-stage driving gear; 12. Second-stage driven gear; 13. Third-stage driving gear; 14. Steering driving gear; 15. Steering driven gear; 16. First-stage sun gear; 17. First-stage planetary gear; 18. First-stage ring gear; 19. First-stage planetary carrier; 20. Second-stage sun gear; 21. Second-stage planetary gear; 22. Second-stage ring gear; 23. Second-stage planetary carrier; 24. Right half shaft gear; 25. Left half shaft gear; 26. Differential planetary gear; 27. Cross shaft; 28. Differential housing; 29. ​​Steering engagement gear; 30. Input engagement gear; 31. Straight-line engagement gear; 32. Engagement gear sleeve; 33. Brake; 34. Right wheel; 35. Left wheel; 36. Detailed Implementation

[0017] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0018] Please see Figure 1 This is a structural diagram of the dual-motor electric drive bridge with torque control function provided by the present invention.

[0019] The dual-motor electric drive axle with torque control includes a first motor 1, a second motor 2, a switching assembly, a first reduction assembly, a second reduction assembly, a brake 34, a steering reduction gear set, a differential, a left half-shaft 8, and a right half-shaft 7. A left wheel 36 and a right wheel 35 are also introduced.

[0020] The first motor 1 has a first output shaft 3, and the second motor 2 has a second output shaft 6. The first reduction gear assembly includes a first parallel shaft 4, a second parallel shaft 5, a first-stage driving gear 9, a first-stage driven gear 10, a second-stage driving gear 11, a second-stage driven gear 12, a third-stage driving gear 13, and a third-stage driven gear 14. The steering reduction gear set includes a steering driving gear 15 and a steering driven gear 16.

[0021] The second reduction assembly includes a primary reduction unit and a secondary reduction unit, both of which are planetary gear sets. The primary reduction unit includes a primary sun gear 17, a primary planetary gear 18, a primary ring gear 19, and a primary planetary carrier 20. The secondary reduction unit includes a secondary sun gear 21, a secondary planetary gear 22, a secondary ring gear 23, and a secondary planetary carrier 24. The differential includes a right half-shaft gear 25, a left half-shaft gear 26, a differential planetary gear 27, a cross shaft 28, and a differential housing 29. The switching assembly includes a steering engagement gear 30, an input engagement gear 31, a straight-line engagement gear 32, and an engagement gear sleeve 33.

[0022] The first output shaft 3 is fixedly equipped with a primary drive gear 9, the first parallel shaft 4 is fixedly equipped with a primary driven gear 10 and a secondary drive gear 11, the second parallel shaft 5 is fixedly equipped with a secondary driven gear 12 and a tertiary drive gear 13, and the differential housing 29 is fixedly equipped with a tertiary driven gear 14. The first output shaft 3, the first parallel shaft 4, and the second parallel shaft 5 are parallel to each other, and the six gears from the primary drive gear 9 to the tertiary driven gear 14 mesh sequentially to form a three-stage parallel shaft reduction mechanism.

[0023] A steering drive gear 15 is slidably mounted on the second output shaft 6, and a steering engagement gear 30 is located to the right of the steering drive gear 15. The second output shaft 6 passes through the steering drive gear 15 and has an input engagement gear 31 at its end located to the right of the steering engagement gear 30. The left end of the first parallel shaft 4 passes through the first-stage driven gear 10 and is fixedly equipped with a straight engagement gear 32. The engagement gear sleeve 33 slides left and right, switching between three states: being located at the input engagement gear 31, engaging the input engagement gear 31 and the steering engagement gear 30, and engaging the input engagement gear 31 and the straight engagement gear 32.

[0024] The internal structure of the differential is consistent with existing technology, so it will not be described in detail. The left half-shaft 8 has a primary reduction unit and a secondary reduction unit arranged from right to left.

[0025] The first-stage sun gear 17 is slidably fitted onto the left half-shaft 8 and fixed to the axle housing. The first-stage planetary carrier 20 is joined on the right side, slidably fitted onto the left half-shaft 8, and extends to the right along the left half-shaft 8. A third-stage driven gear 14 is fixedly provided on the outer side of the extension section, and the right end is fixedly connected to the differential housing 29. The first-stage ring gear 19 is fixedly connected to the second-stage ring gear 23. The second-stage planetary carrier 24 is fixedly connected to the left half-shaft 8. The second-stage sun gear 21 is slidably fitted onto the left half-shaft 8 and extends to the left along the left half-shaft 8. A steering driven gear 16 is fixedly provided on the outer side of the extension section.

[0026] The steering drive gear 15 meshes with the steering driven gear 16, and the transmission occurs between the steering engagement gear 30 and the secondary sun gear 21.

[0027] The brake 34 is located on the axle housing and connected to the secondary sun gear 21. The brake 34 can activate and lock the secondary sun gear 21, or deactivate and release the secondary sun gear 21.

[0028] Ws1 represents the first-stage sun gear at 17 RPM, Wr1 represents the first-stage ring gear at 19 RPM, Wc1 represents the first-stage planetary carrier at 20 RPM, Wra represents the right half-shaft at 7 RPM, Wla represents the left half-shaft at 8 RPM, Wd represents the differential housing at 29 RPM, and k represents the ratio of the number of teeth on the ring gear to the number of teeth on the sun gear.

[0029] The following relationship exists: Ws1+k×Wr1=(k+1)×Wc1 Ws² + k × Wr² = (k + 1) × Wc² Since Ws1=0, Wr1=Wr2 Therefore, Ws² + (k+1) × Wc₁ = (k+1) × Wc₂ Since 2Wd = Wra + Wla, Wc1 = Wd, Wc2 = Wla Therefore, Ws² + (k+1)Wra / 2 = (k+1)Wla / 2 Ws2 is controlled by the second motor 2.

[0030] If Ws2 is positive, then the left wheel 36 rotates faster and the right wheel 35 rotates slower; If Ws2 is negative, then the left wheel 36 rotates slowly and the right wheel 35 rotates quickly.

[0031] Ts2 represents the torque of the second-stage sun gear 21 (controlled by the second motor 2), Tc2 represents the torque of the second-stage planetary carrier 24, Tm represents the torque input from the first motor 1 to the differential housing 29, Td represents the load torque of the differential housing 29, Tla represents the torque of the left half-shaft 8, and Tra represents the torque of the right half-shaft 7. Since the two planetary gear sets have the same number of teeth, Tc2 = Tc1.

[0032] When the second motor 2 is not engaged, it functions as a traditional differential. Tm=Td, Tla=Tra=Td / 2=Tm / 2 When the second motor 2 intervenes and provides torque in the same direction: Tm=Td+Tc1, Tla=(Tm-Tc1) / 2+Tc2=(Tm+Tc2) / 2, Tra=(Tm-Tc2) / 2, the torque of the left wheel is greater than that of the right wheel.

[0033] When the second motor 2 intervenes and provides reverse torque: Tm+Tc1=Td, Tla=(Tm+Tc1) / 2-Tc2=(Tm-Tc2) / 2, Tra=(Tm+Tc2) / 2, the torque of the left wheel is smaller than that of the right wheel.

[0034] Based on the above derivation, by controlling the opening and closing of the brake 24, the switching of the gear sleeve 33 between the three states, and the forward or reverse rotation of the second motor 2, four driving states can be formed: single-motor straight-line, dual-motor straight-line, left turn, and right turn.

[0035] Please also refer to Figures 2 to 5 These are the power flow diagrams of the dual-motor electric drive bridge with torque control function provided by the present invention in single-motor straight-line drive state, dual-motor straight-line drive state, left-turn drive state, and right-turn drive state.

[0036] When the control brake 24 is activated, the engagement sleeve 33 is located at the input engagement tooth 31 and is not engaged with other teeth. The first motor 1 rotates forward and the second motor 2 is turned off, which is a single motor straight drive state.

[0037] When the control brake 24 is activated, the gear sleeve 33 engages the input engagement gear 31 and the straight engagement gear 32, causing the first motor 1 to rotate forward and the second motor 2 to rotate forward, thus achieving a dual-motor straight-drive state.

[0038] When the control brake 24 is closed, the gear sleeve 33 engages the input engagement gear 31 and the steering engagement gear 30, causing the first motor 1 to rotate forward and the second motor 2 to rotate forward, which is the right-turn drive state.

[0039] When the control brake 24 is closed, the gear sleeve 33 engages the input engagement gear 31 and the steering engagement gear 30, the first motor 1 rotates forward and the second motor 2 rotates in reverse, which is the left-turn drive state.

[0040] In single-motor straight-drive mode, the first motor 1 drives the differential housing 29 through the first reduction gear assembly, and the second motor 2 stops. With the brake 34 activated, the first-stage sun gear 17 and the second-stage sun gear 21 are fixed, while the first-stage planetary carrier 20 and the second-stage planetary carrier 24 rotate freely with the differential housing 29 and the left half-shaft 8, respectively. This is equivalent to a conventional differential.

[0041] In the dual-motor straight-drive mode, the first motor 1 drives the differential housing 29 through the first reduction gear assembly. The second motor 2 drives the first parallel shaft 4 sequentially through the second output shaft 6, input engagement gear 31, engagement gear sleeve 33, and straight-drive engagement gear 32, thus merging the power of the first motor 1. Only the power is enhanced; other states are the same as in the single-motor straight-drive mode.

[0042] In right-turn drive mode, the first motor 1 still drives the differential housing 29 through the first reduction gear assembly. The second motor 2 drives the second-stage sun gear 21 sequentially through the second output shaft 6, input engagement gear 31, engagement gear sleeve 33, steering engagement gear 30, steering drive gear 15, and steering driven gear 16. The power from the second-stage sun gear 21 drives the left half-shaft 8 through the first-stage planetary carrier 20, and also drives the differential housing 29 through the first-stage ring gear 19 and the first-stage planetary carrier 20, ultimately driving the left half-shaft 8. The left wheel 36 receives both higher speed and torque. By controlling the speed of the second motor 2, the difference between the speed and torque of the left wheel 36 can be controlled, achieving active control.

[0043] In left-turn drive mode, the power flow of the first motor 1 and the second motor 2 is the same as in right-turn mode. Since the second motor 2 rotates in reverse, the power of the left half-shaft 8 flows back to the second reduction gear via the secondary planetary carrier 24 and is used to drive the right half-shaft 7, resulting in greater speed and torque for the right wheel 35. Active control is achieved using the same method as in right-turn mode.

[0044] A control method for a dual-motor electric drive bridge, based on the above control scheme, controls the dual-motor electric drive bridge with torque control function to switch between four driving states: single-motor straight-line, dual-motor straight-line, left turn, and right turn, and further realizes active control.

[0045] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention specification, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A dual-motor electric drive bridge with torque control function, characterized in that: The system includes a first motor, a second motor, a switching assembly, a first reduction assembly, a second reduction assembly, a differential, and two output half-shafts connected to the differential. The second reduction assembly includes a brake, a primary reduction unit, and a secondary reduction unit. The secondary reduction unit is a planetary gear set. The first motor is connected to the housing of the differential through the first reduction assembly. The second motor is connected to the first reduction assembly through the switching assembly, or connected to the sun gear of the secondary reduction unit through the switching assembly. The planet carrier of the secondary reduction unit is connected to one of its output half-shafts. The ring gear of the secondary reduction unit is connected to the housing of the differential through the primary reduction unit. The brake is located on the axle housing and connected to the sun gear of the secondary reduction unit.

2. The dual-motor electric drive bridge with torque control function according to claim 1, characterized in that: The first-stage reduction unit is a planetary gear set. The gear ring of the first-stage reduction unit is connected to the gear ring of the second-stage reduction unit. The planet carrier of the first-stage reduction unit is connected to the housing of the differential. The sun gear of the first-stage reduction unit is fixedly connected to the axle housing.

3. The dual-motor electric drive bridge with torque control function according to claim 2, characterized in that: The number of teeth in the first-stage reduction unit is the same as that in the second-stage reduction unit.

4. The dual-motor electric drive bridge with torque control function according to any one of claims 1 to 3, characterized in that: The first deceleration component is a three-stage parallel shaft deceleration component.

5. The dual-motor electric drive bridge with torque control function according to claim 4, characterized in that: The first reduction gear assembly includes three-stage reduction gears and two parallel shafts. The first-stage reduction gear connects the output shaft of the first motor and the first parallel shaft. The second-stage reduction gear connects the first parallel shaft and the second parallel shaft. The third-stage reduction gear connects the second parallel shaft and the housing of the differential. The second motor is connected to the first parallel shaft through the switching assembly.

6. The dual-motor electric drive bridge with torque control function according to claim 5, characterized in that: The switching component includes an input engagement tooth, a straight engagement tooth, a steering engagement tooth, and an engagement tooth sleeve. The input engagement tooth is connected to the output shaft of the second motor, the straight engagement tooth is connected to the first reduction assembly, the steering engagement tooth is connected to the sun gear of the second-stage reduction unit, and the engagement tooth sleeve engages with the input engagement tooth and the straight engagement tooth, or engages with the input engagement tooth and the steering engagement tooth, or does not engage with either.

7. The dual-motor electric drive bridge with torque control function according to claim 6, characterized in that: It also includes a steering reduction gear set, wherein the steering engagement gear is located on the steering reduction gear set and is connected to the sun gear of the secondary reduction unit through the steering reduction gear set.

8. The dual-motor electric drive bridge with torque control function according to claim 6 or 7, characterized in that: This includes drive states such as single-motor straight-ahead, dual-motor straight-ahead, left turn, and right turn; In single-motor straight-line drive and dual-motor straight-line drive states, the brake is activated and the sun gear of the secondary reduction unit is fixed. In single-motor straight-line drive state, the engagement sleeve is isolated, the first motor drives the first reduction assembly, and the second motor stops. In dual-motor straight-line drive state, the engagement sleeve engages the input engagement tooth and the straight-line engagement tooth, and the first motor and the second motor jointly drive the first reduction assembly. In left-turn and right-turn driving states, the brake is closed and the sun gear of the secondary reduction unit is released. The engagement gear engages the input engagement gear and the steering engagement gear. The first motor drives the first reduction assembly, and the second motor drives the sun gear of the secondary reduction unit. In left-turn driving state, the second motor is in the opposite direction to the first motor. In right-turn driving state, the second motor is in the same direction as the first motor.

9. The dual-motor electric drive bridge with torque control function according to claim 8, characterized in that: In left-turn drive mode, the rotational speed and torque of the left-side output half-shaft are both less than those of the right-side output half-shaft; in right-turn drive mode, the rotational speed and torque of the left-side output half-shaft are greater than those of the right-side output half-shaft.

10. A control method for a dual-motor electric drive bridge, characterized in that: Based on the dual-motor electric drive axle with torque control function as described in claim 8 or 9, the control method of the dual-motor electric drive axle is used to control the dual-motor electric drive axle with torque control function to switch between four driving states: single-motor straight driving, dual-motor straight driving, left turn, and right turn; by controlling the speed of the second motor, the torque and speed difference between the two vehicles on both sides during steering is actively controlled.

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