Dual-motor planetary gear train variable speed system and variable speed control method thereof

Abstract

The double-motor planetary gear train variable speed system of the application is designed by coupling double motors with a multi-gear variable speed planetary gear train, increases the high-efficiency operation interval of the motor, meets the driving demand under different working conditions, reduces energy consumption, forms an independent reverse gear position, improves the reliability of the system structure under extreme working conditions, improves the working condition adaptability of the variable speed system, forms a composite transmission architecture by coupling the assembly with the planetary gear train with three groups of star rows, optimizes the spatial layout of the system, improves the compactness of the structure of the variable speed system, shortens the axial dimension and reduces the weight of the system, sets a brake and a clutch in the planetary gear train, forms multi-gear switching, both expands the multi-gear position and optimizes the compact layout, and eliminates the gear shifting impact, improving the driving experience. The application also provides a variable speed control method for the double-motor planetary gear train variable speed system.

Description

Technical Field

[0001] This invention relates to a dual-motor planetary gear train transmission system and its transmission control method, belonging to the field of pure electric transmission technology. Background Technology

[0002] As electric vehicles increasingly demand high-efficiency and multi-scenario power output, single-motor electric drive axle solutions face significant limitations. This is because single high-power motors are expensive and inefficient under low-load conditions, often resulting in high overall vehicle energy consumption and unsatisfactory power performance. With technological advancements, dual-motor electric drive axles are becoming increasingly popular. By combining two relatively smaller-power motors, system costs are reduced, and precise speed ratio configurations allow the motors to operate more frequently in their efficient operating range, significantly improving vehicle economy and driving experience.

[0003] However, existing dual-motor multi-speed electric drive systems have significant drawbacks in their reverse gear design, which relies on the motor's reversal. When the motor reverses at high speed, the oil seals are prone to failure due to reverse oil pressure leakage. Furthermore, conventional unidirectional rotary oil pumps cannot supply oil under reverse conditions, creating a lubrication blind spot and resulting in insufficient lubrication of transmission components, affecting their lifespan and safety. Moreover, although planetary gear sets can achieve speed ratio switching via brakes, existing technologies mostly rely on a single mechanical structure (such as a parallel shaft or planetary gear set), making it difficult to balance multi-speed expansion and a compact layout. Summary of the Invention

[0004] The dual-motor planetary gear transmission system provided by this invention features a multi-speed transmission design combining dual-motor coupling with a planetary gear train. This increases the high-efficiency operating range of the motors, meets the driving requirements under different operating conditions, and forms an independent reverse gear. This improves the reliability of the system structure under extreme conditions and enhances the adaptability of the transmission system. It balances multi-speed expansion and a compact layout while eliminating shift shock, thus improving the driving experience. This invention also provides a transmission control method for the dual-motor planetary gear transmission system.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A dual-motor planetary gear train transmission system includes a coupling component that couples the power of two motors and a planetary gear train connected to the output end of the coupling component. The planetary gear train comprises a first planetary gear set, a second planetary gear set, and a third planetary gear set connected sequentially from front to back. A first brake is mounted on the second planetary gear set, and a second brake is mounted on the third planetary gear set. The output ends of the first and third planetary gear sets are connected by a clutch. The planetary gear train outputs forward gear power when the second brake or the clutch is activated, or outputs reverse gear power when the first brake is activated.

[0006] Preferably, the coupling assembly includes two motors, an input shaft connected to the shaft end of the motors, and a constant meshing shaft meshing with the two input shafts respectively, the constant meshing shaft being connected to the input end of the planetary gear train.

[0007] Preferably, the front end of the constant meshing shaft is fitted with a lubrication pump that pumps lubricating fluid for the entire system.

[0008] Preferably, the first planetary gear set includes a first sun gear connected to a constant meshing shaft, a first planet gear meshing with the first sun gear, a first planet carrier mounted on the first planet gear, and a first gear ring with an inner ring meshing with the first planet gear. The second planetary gear set includes a second sun gear, a second planet gear meshing with the second sun gear, a second planet carrier mounted on the second planet gear, and a second gear ring with an inner ring meshing with the second planet gear. The third planetary gear set includes a third sun gear, a third planet gear meshing with the third sun gear, a third planet carrier mounted on the third planet gear, and a third gear ring with an inner ring meshing with the third planet gear. The first gear ring is fixed, the first planet carrier, the second sun gear, and the third sun gear are fixedly connected, the second gear ring is fixedly connected to the third planet carrier, an output shaft is mounted on the third planet carrier, and the first planet carrier and the output shaft are connected via a clutch.

[0009] Preferably, the first brake is mounted on the second planetary carrier, and the second brake is mounted on the third gear ring.

[0010] Preferably, the intermediate shaft is coaxially fixed on the first planetary carrier, the second sun gear and the third sun gear are fixed on the intermediate shaft, and the clutch is installed between the intermediate shaft and the output shaft, so that the intermediate shaft and the output shaft are connected by the engagement of the clutch.

[0011] The speed control method for the dual-motor planetary gear transmission system described above is characterized by: When the first brake and clutch are closed, the second brake is engaged, and the planetary gear system outputs power in forward gear; With the first and second brakes engaged, the clutch is activated, and the planetary gear system outputs forward second gear power. When the second brake and clutch are closed, the first brake is engaged, and the planetary gear system outputs reverse gear power.

[0012] Preferred, When the planetary gears output first gear power, the coupling assembly drives the first sun gear to rotate, and the power of the first sun gear is transmitted through the first planet carrier and the third sun gear to the third planet carrier and the output shaft; When the planetary gear outputs second-gear power, the coupling assembly drives the first sun gear to rotate, and the power of the first sun gear is transmitted to the output shaft through the first planetary carrier; When the planetary gears output reverse gear power, the coupling assembly drives the first sun gear to rotate, and the power of the first sun gear is transmitted through the first planetary carrier, the second sun gear, and the second ring gear to the third planetary carrier and the output shaft.

[0013] The beneficial effects of this invention are: The dual-motor planetary gear train transmission system of this invention uses a coupling component to couple and transmit the power of two motors to the planetary gear train. The planetary gear train has three planetary gear sets. Brakes are mounted on the second and third planetary gear sets. A clutch connects the output shaft of the first planetary gear set to the output end of the third planetary gear set. The planetary gear train outputs forward gear power when the second brake or clutch is activated, or outputs reverse gear power when the first brake is activated. The dual-motor coupling combined with the multi-speed transmission design of the planetary gear train increases the high-efficiency operating range of the motors, meets the driving requirements under different working conditions, reduces energy consumption, and avoids reliance on external power. Reverse gear is achieved by reversing the motor, thus avoiding the risk of system oil seal failure caused by reverse gear. An independent reverse gear is formed, improving the reliability of the system structure under extreme conditions and enhancing the adaptability of the transmission system. The coupling component and the planetary gear train with three sets of star rows form a composite transmission architecture, optimizing the system space layout, improving the structural compactness of the transmission system, shortening the axial dimension and reducing the system weight. The brake and clutch are set in the planetary gear train to form multi-gear switching, which takes into account both multi-gear expansion and compact layout, while eliminating shift shock and improving the driving experience. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the transmission structure of the dual-motor planetary gear system in a specific implementation.

[0015] Figure 2 A schematic diagram of the transmission structure of a dual-motor planetary gear transmission system when outputting power to advance one gear.

[0016] Figure 3 A schematic diagram of the transmission structure of a dual-motor planetary gear transmission system when outputting forward second gear power.

[0017] Figure 4 A schematic diagram of the transmission structure of a dual-motor planetary gear transmission system when outputting reverse gear power. Detailed Implementation

[0018] The following is combined Figures 1-4 The embodiments of the present invention will be described in detail below.

[0019] A dual-motor planetary gear transmission system includes a coupling component 1 that couples the power of two motors and a planetary gear train connected to the output end of the coupling component 1. The planetary gear train comprises a first planetary gear set 2, a second planetary gear set 3, and a third planetary gear set 4 connected sequentially from front to back. A first brake 5 is mounted on the second planetary gear set 3, and a second brake 6 is mounted on the third planetary gear set 4. The output ends of the first planetary gear set 2 and the third planetary gear set 4 are connected by a clutch 7. The planetary gear train outputs forward gear power when the second brake 6 or the clutch 7 is activated, or outputs reverse gear power when the first brake is activated.

[0020] The dual-motor planetary gear transmission system described above uses a coupling component 1 to couple and transmit the power of the two motors to the planetary gear train. The planetary gear train has three planetary gear sets. Brakes are mounted on the second planetary gear set 3 and the third planetary gear set 4. A clutch 7 connects the output shaft of the first planetary gear set 2 to the output end of the third planetary gear set 4. The planetary gear train outputs forward gear power when the second brake 6 or clutch 7 is activated, or outputs reverse gear power when the first brake 5 is activated. The dual-motor coupling combined with the multi-speed transmission design of the planetary gear train increases the high-efficiency operating range of the motors, meets the driving requirements under different working conditions, and reduces energy consumption. To avoid relying on motor reversal to achieve reverse gear, thus mitigating the risk of system oil seal failure due to motor reversal forming reverse gear, an independent reverse gear is formed, improving the reliability of the system structure under extreme working conditions and enhancing the working condition adaptability of the transmission system. The coupling component 1 and the planetary gear train with three sets of star rows form a composite transmission architecture, optimizing the system spatial layout, improving the structural compactness of the transmission system, shortening the axial dimension and reducing the system weight. Brakes and clutches are set in the planetary gear train to form multi-gear switching, which takes into account both multi-gear expansion and compact layout, while eliminating shift shock and improving the driving experience.

[0021] The coupling assembly 1 includes two motors 11, an input shaft 12 connected to the shaft ends of the motors 11, and a constant meshing shaft 13 meshing with the two input shafts 12 respectively. The constant meshing shaft 13 is connected to the input end of the planetary gear train. The input shaft 13 meshes with the constant meshing shaft 13, coupling the power of the two motors 11 to the constant meshing shaft 13. The constant meshing shaft 13 transmits the power to the planetary gear train. The coupling assembly 1 has a parallel shaft structure. The constant meshing shaft 13 rotates when the motors start, transmitting the power to the planetary gear train. The planetary gear train cannot output power when the first brake, the second brake, and the clutch are not engaged. Power can only be output when the first brake, the second brake, or the clutch is engaged.

[0022] The front end of the constant meshing shaft 13 is equipped with a lubrication pump 14, which pumps lubricating fluid for the entire system. After the motor starts, the constant meshing shaft 13 rotates, driving the lubrication pump 14 to pump oil to lubricate the gears and bearings in the entire system. The constant meshing shaft 13 is not affected by gear shifting and can drive the lubrication pump 14 in forward, reverse, and neutral gears, ensuring a continuous and stable supply of lubricating oil under any operating condition. This solves the lubrication blind spot problem caused by oil pump failure during reverse rotation in traditional electric drive systems. The independent control of reverse gear protects the sealing effect of the oil seal in the system, and the directional continuous oil supply of the lubrication pump protects the lubrication capacity of the system, providing dual protection for the transmission system and significantly improving the structural reliability and stability of the transmission system under extreme operating conditions.

[0023] The first planetary gear set 2 includes a first sun gear 21 connected to a constant meshing shaft, a first planet gear meshing with the first sun gear 21, a first planet carrier 22 mounted on the first planet gear, and a first gear ring 23 whose inner ring meshes with the first planet gear. The second planetary gear set 3 includes a second sun gear 31, a second planet gear meshing with the second sun gear 31, a second planet carrier 32 mounted on the second planet gear, and a second gear ring 33 whose inner ring meshes with the second planet gear. The third planetary gear set 4 includes a third sun gear 41, a third planet gear meshing with the third sun gear 41, a third planet carrier 42 mounted on the third planet gear, and a third gear ring 43 whose inner ring meshes with the third planet gear. The first gear ring 23 is fixed. The first planet carrier 22, the second sun gear 31, and the third sun gear 41 are fixedly connected. The second gear ring 33 is fixedly connected to the third planet carrier 42. An output shaft 44 is mounted on the third planet carrier 42. The first planet carrier 22 and the output shaft 44 are connected by a clutch 7. The first gear ring 23 is fixed, so that the first planetary gear set 2 can only output power from the first planetary carrier 22. When the clutch is engaged, the first planetary carrier 22 is connected to the output shaft 44, and the power of the first planetary carrier 22 is directly transmitted to the output shaft. At this time, the second planetary gear set 3 and the third planetary gear set 4 do not participate in the transmission. Only when the clutch is closed and the first brake or the second brake is engaged can the second planetary gear set 3 and the third planetary gear set 4 participate in the transmission. During driving, only one of the clutch, the first brake, and the second brake needs to be engaged, making gear shifting control simple and avoiding gear shifting shock.

[0024] The first brake 5 is mounted on the second planetary carrier 32, and the second brake 6 is mounted on the third ring gear 43. When neither the first brake nor the clutch is engaged, and only the second brake 6 is engaged, the power of the coupling assembly 1 is transmitted from the constant engagement shaft 13 to the first sun gear 21. The power of the first sun gear 21 is transmitted to the first planetary carrier 22, which drives the third sun gear 43. The third sun gear 41 then transmits power to the third planetary carrier 42, and the power is output from the output shaft 44, forming the forward gear of the transmission system to meet the high torque drive requirements under heavy load conditions. When both the first brake 5 and the second brake 6 are closed, and only the clutch is engaged, the power of the coupling assembly 1 is transmitted from the constant engagement shaft 13 to the first sun gear 21. The power of the first sun gear 21 is transmitted to the first planetary carrier 22, which directly drives the output shaft 44. The transmission system generates a second-gear forward power. The torque of the second-gear forward power is less than that of the first-gear forward power, but the speed is greater than that of the first-gear forward power. The second-gear forward power meets the low-torque, high-speed drive requirements under light load conditions. When the second brake and clutch are both closed, and only the first brake is working, the power of the coupling assembly 1 is frequently transmitted to the first sun gear 21 through the meshing shaft 13. The power of the first sun gear 21 is transmitted to the first planetary carrier 22, and the first planetary carrier 22 transmits the power to the second sun gear 31. Since the second planetary carrier 32 is fixed by the first brake 5, the second sun gear 31 will drive the second ring gear 33 to rotate in the opposite direction. The third planetary carrier 42 rotates in the opposite direction coaxially with the second ring gear 33, causing the output shaft 44 to rotate in the opposite direction, thus forming the reverse gear power of the transmission system.

[0025] In this configuration, an intermediate shaft 24 is coaxially fixed on the first planetary carrier 22. A second sun gear 31 and a third sun gear 41 are fixed on the intermediate shaft 24. A clutch 7 is mounted between the intermediate shaft 24 and the output shaft 44, connecting the intermediate shaft 24 and the output shaft 44 through the engagement of the clutch 7. The intermediate shaft 24 can be integrally formed with the first planetary carrier 22. The second sun gear 31 and the third sun gear 41, mounted on the intermediate shaft 24, rotate synchronously with the rotation of the first planetary carrier 22. When the clutch 7 is engaged, it connects the intermediate shaft 24 and the output shaft 44; when the clutch 7 is disengaged, the connection between the intermediate shaft 24 and the output shaft 44 is broken.

[0026] The speed control method for the dual-motor planetary gear transmission system described above is characterized by: When the first brake 5 and clutch 7 are closed, the second brake 6 is engaged, and the planetary gear system outputs power in forward gear one. When the first brake 5 and the second brake 6 are closed, the clutch 7 is engaged, and the planetary gear system outputs forward second gear power. When the second brake 6 and clutch 7 are closed, the first brake 5 is engaged, and the planetary gear system outputs reverse gear power.

[0027] The aforementioned transmission control method involves the planetary gear system outputting forward first gear power upon activation of the second brake 6, forward second gear power upon activation of the clutch 7, or reverse gear power upon activation of the first brake 5. The forward first gear power meets the high torque drive requirements under heavy load conditions. The forward second gear power has a lower torque but higher speed than the forward first gear power, meeting the low torque and high speed drive requirements under light load conditions. The multi-gear transmission design combining dual-motor coupling with the planetary gear system increases the efficient operating range of the motors, meets the drive requirements under different operating conditions, reduces energy consumption, avoids relying on motor reversal to achieve reverse gear, and mitigates the risk of system oil seal failure due to motor reversal forming reverse gear. It also forms an independent reverse gear, improving the reliability of the system structure under extreme operating conditions and enhancing the adaptability of the transmission system.

[0028] in, When the planetary gear outputs first gear power, the coupling component 1 drives the first sun gear 21 to rotate, and the power of the first sun gear 21 is transmitted to the third planetary carrier 42 and the output shaft 44 through the first planetary carrier 22 and the third sun gear 41. When the planetary gear outputs second-gear power, the coupling assembly 1 drives the first sun gear 21 to rotate, and the power of the first sun gear 21 is transmitted to the output shaft 44 via the first planet carrier 22; When the planetary gear outputs reverse gear power, the coupling assembly 1 drives the first sun gear 21 to rotate, and the power of the first sun gear 21 is transmitted to the third planetary carrier 42 and the output shaft 44 through the first planetary carrier 22, the second sun gear 31, and the second ring gear 33.

[0029] When neither the first brake nor the clutch is engaged, and only the second brake 6 is engaged, the power of the coupling assembly 1 is transmitted from the constant engagement shaft 13 to the first sun gear 21. The power of the first sun gear 21 is transmitted to the first planetary carrier 22, which drives the third sun gear 43. The third sun gear 43 transmits power to the third planetary carrier 42, and the power is output through the output shaft 44, forming the forward gear of the transmission system. When both the first and second brakes are closed, and only the clutch is engaged, the power of the coupling assembly 1 is transmitted from the constant engagement shaft 13 to the first sun gear 21. The power of the first sun gear 21 is transmitted to the first planetary carrier 22, and the third sun gear 43 drives the third sun gear 43. The third sun gear 43 transmits power to the third planetary carrier 42, and the power is output through the output shaft 44, forming the forward gear of the transmission system. The planetary carrier 22 directly drives the output shaft 44 to move, forming the forward second gear power of the transmission system. When the second brake and clutch are closed and only the first brake is working, the power of the coupling component 1 is frequently transmitted to the first sun gear 21 through the meshing shaft 13. The power of the first sun gear 21 is transmitted to the first planetary carrier 22, and the first planetary carrier 22 transmits the power to the second sun gear 31. Since the second planetary carrier 32 is fixed by the first brake 5, the second sun gear 31 will drive the second ring gear 33 to rotate in the opposite direction. The third planetary carrier 42 rotates in the opposite direction coaxially with the second ring gear 33, causing the output shaft 44 to rotate in the opposite direction, forming the reverse gear power of the transmission system.

[0030] The technical solutions of the embodiments of the present invention have been fully described above with reference to the accompanying drawings. It should be noted that the described embodiments are only a part of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

Claims

1. A dual-motor planetary gear train transmission system, comprising a coupling assembly for power coupling of two motors and a planetary gear train connected to the output end of the coupling assembly, characterized in that: The planetary gear train includes a first planetary gear set, a second planetary gear set, and a third planetary gear set connected in sequence from front to back. The second planetary gear set is equipped with a first brake, and the third planetary gear set is equipped with a second brake. The planetary gear train outputs forward gear power when the second brake or clutch is activated, or outputs reverse gear power when the first brake is activated. The coupling assembly includes two motors, an input shaft connected to the shaft end of the motors, and a constant meshing shaft meshing with the two input shafts respectively. The constant meshing shaft is connected to the input end of the planetary gear train. The first planetary gear set includes a first sun gear connected to a constant meshing shaft, a first planet gear meshing with the first sun gear, a first planet carrier mounted on the first planet gear, and a first gear ring with an inner ring meshing with the first planet gear. The second planetary gear set includes a second sun gear, a second planet gear meshing with the second sun gear, a second planet carrier mounted on the second planet gear, and a second gear ring with an inner ring meshing with the second planet gear. The third planetary gear set includes a third sun gear, a third planet gear meshing with the third sun gear, a third planet carrier mounted on the third planet gear, and a third gear ring with an inner ring meshing with the third planet gear. The first gear ring is fixed, the first planet carrier, the second sun gear, and the third sun gear are fixedly connected, the second gear ring is fixedly connected to the third planet carrier, an output shaft is mounted on the third planet carrier, and the first planet carrier is connected to the output shaft via a clutch. The first brake is mounted on the second planetary carrier, and the second brake is mounted on the third gear ring.

2. The dual-motor planetary gear transmission system according to claim 1, characterized in that: The front end of the constant meshing shaft is fitted with a lubrication pump that pumps lubricating fluid to the entire system.

3. The dual-motor planetary gear transmission system according to claim 1, characterized in that: The intermediate shaft is coaxially fixed on the first planetary carrier, the second sun gear and the third sun gear are fixed on the intermediate shaft, and the clutch is installed between the intermediate shaft and the output shaft. The intermediate shaft and the output shaft are connected by the engagement of the clutch.

4. The speed control method for the dual-motor planetary gear train transmission system according to any one of claims 1 to 3, characterized in that: When the first brake and clutch are closed, the second brake is engaged, and the planetary gear system outputs power in forward gear; With the first and second brakes engaged, the clutch is activated, and the planetary gear system outputs forward second gear power. When the second brake and clutch are closed, the first brake is engaged, and the planetary gear system outputs reverse gear power.

5. The speed control method for the dual-motor planetary gear train transmission system according to claim 4, characterized in that: When the planetary gears output first gear power, the coupling assembly drives the first sun gear to rotate, and the power of the first sun gear is transmitted through the first planet carrier and the third sun gear to the third planet carrier and the output shaft; When the planetary gear outputs second-gear power, the coupling assembly drives the first sun gear to rotate, and the power of the first sun gear is transmitted to the output shaft through the first planetary carrier; When the planetary gears output reverse gear power, the coupling assembly drives the first sun gear to rotate, and the power of the first sun gear is transmitted through the first planetary carrier, the second sun gear, and the second ring gear to the third planetary carrier and the output shaft.

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