Four-motor four-gear compound transmission integrated system and its transmission control method

Abstract

The four-motor four-gear composite transmission integrated system of the application utilizes the characteristics of large speed ratio of the planetary gear train to effectively improve the torque, and realizes multi-gear power output through control of the first brake, the second brake and the clutch assembly, forms effective matching from low-speed large torque to high-speed low energy consumption, and improves the speed domain bandwidth; the clutch assembly and the brake are arranged in the planetary gear train to realize gear shifting, which not only avoids increase of the axial size of the system due to increase of the gear setting, but also avoids gear shifting impact of the parallel shaft, improves gear shifting smoothness and efficiency, the coupling assembly of the parallel shaft structure is combined with the transmission mechanism of the double planetary gear train structure, which not only improves the coupling efficiency of the motor and the transmission mechanism, but also improves the structural compactness and reduces the axial size of the system, which is beneficial to vehicle arrangement; the system power output can still be maintained through the remaining motor and the adaptive gear when single motor failure occurs, which significantly enhances the system robustness. The application also provides a transmission control method of the four-motor four-gear composite transmission integrated system.

Description

Technical Field

[0001] This invention relates to an integrated system of a four-motor, four-speed composite transmission 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, traditional single-speed electric drive systems, with their fixed transmission ratios, struggle to balance low-speed torque and high-speed efficiency. To improve power flexibility, pure electric transmissions have developed multi-motor, multi-gear transmission technology, making multi-gear transmission a key direction for enhancing the overall performance of electric drive systems. Existing electric drive transmissions mostly employ planetary gear sets and parallel shaft structures. Planetary gear sets increase the speed ratio and output torque, while parallel shaft structures provide shifting transmission. However, parallel shaft structures suffer from shift shock, power interruption, insufficient gear expandability, and low gear switching efficiency. Furthermore, the multi-gear configuration in parallel shaft structures creates structural redundancy, increasing the axial space of the transmission and hindering overall vehicle layout.

[0003] In addition, while multi-motor coordinated multi-speed drive technology can improve power flexibility, the coupling efficiency between the motor and the transmission mechanism is low. Summary of the Invention

[0004] The four-motor, four-speed composite transmission integrated system provided by this invention achieves an effective match from low-speed, high-torque to high-speed, low-energy consumption, increasing speed bandwidth, improving shift smoothness and efficiency. It not only enhances the coupling efficiency between the motor and the transmission mechanism but also improves structural compactness, reduces the system's axial dimensions, facilitates vehicle layout, and significantly enhances system robustness. This invention also provides a transmission control method for the four-motor, four-speed composite transmission integrated system.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: The four-motor four-speed composite transmission system includes a coupling assembly for coupling the power of two motors, an intermediate shaft, a transmission mechanism with four-speed function, and an output shaft. The coupling assembly consists of two sets, symmetrically distributed on both sides of the intermediate shaft and respectively meshing with it. The transmission mechanism includes a first planetary gear set and a second planetary gear set coaxially arranged behind the first planetary gear set. The intermediate shaft is coaxially connected to the sun gear of the first planetary gear set. The output shaft is mounted on the ring gear of the second planetary gear set. The ring gear of the first planetary gear set is fixedly connected to the sun gear of the second planetary gear set. A clutch assembly is installed inside the ring gear of the second planetary gear set. The planet carrier of the first planetary gear set connects to the planet carrier or ring gear of the second planetary gear set as the clutch assembly moves. A first brake is mounted on the ring gear of the first planetary gear set, and a second brake is mounted on the planet carrier of the second planetary gear set.

[0006] Preferably, the coupling assembly includes two motors, an input shaft connected to the motor shaft ends respectively, and a constantly meshed shaft meshing with the input shaft, the constantly meshed shaft meshing with an intermediate shaft.

[0007] Preferably, the first planetary gear set includes a first sun gear coaxially connected to the intermediate 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 output shaft is mounted on the second gear ring. The first gear ring is fixedly connected to the second sun gear. The first planet carrier is connected to the second planet carrier or the second gear ring as the clutch assembly moves. A first brake is mounted on the first gear ring, and a second brake is mounted on the second planet carrier.

[0008] Preferably, the output end of the first planetary carrier is fixed to the engagement gear, and the clutch assembly includes a first clutch that can connect the engagement gear to the second planetary carrier and a second clutch that can connect the engagement gear to the second gear ring.

[0009] Preferably, the first gear ring and the first sun gear are integrally formed, the output end of the first planetary carrier passes through the first gear ring and the second sun gear and extends into the second gear ring, a support gear corresponding to the engaging gear is fixed on the second gear ring, the first clutch is installed between the second planetary carrier and the engaging gear, and the second clutch is installed between the engaging gear and the support gear.

[0010] Preferably, the first clutch is a sliding gear sleeve that can slide axially on the second planetary carrier and engages with the engagement gear by sliding to the right on the second planetary carrier. The second clutch is a sliding gear sleeve that can slide axially on the support gear and engages with the engagement gear by sliding to the left on the support gear.

[0011] The speed control method of the four-motor four-speed composite transmission integrated system described above The four-speed power of the four-motor four-speed composite transmission system is formed by controlling the clutch assembly, the first brake, and the second brake. The characteristic feature is that the control method from first gear to fourth gear is as follows: When the first brake is engaged, the clutch assembly moves to connect the planet carrier of the first planetary gear set with the ring gear of the second planetary gear set, forming the first gear. When the second brake is engaged, the clutch assembly moves to connect the planet carrier of the first planetary gear set with the planet carrier of the second planetary gear set, forming second gear power; When the first brake is engaged, the clutch assembly moves to connect the planet carrier of the first planetary gear set with the ring gear of the second planetary gear set, forming a three-speed power. When the first brake is engaged, the clutch assembly moves to connect the planet carrier of the first planetary gear set with the planet carrier of the second planetary gear set, forming a fourth gear.

[0012] Preferred, "The movement of the clutch assembly connects the planet carrier of the first planetary gear set with the ring gear of the second planetary gear set" means that the second clutch slides to the left on the support gear and engages with the engagement gear; "The movement of the clutch assembly connects the planet carrier of the first planetary gear set with the planet carrier of the second planetary gear set" means that the first clutch slides to the right on the second planetary carrier and engages with the engagement gear.

[0013] The beneficial effects of this invention are: The four-motor four-speed composite transmission gearbox integrated system of the present invention has a coupling component that couples the power of two motors, and the power of the two sets of coupling components is coupled to the intermediate shaft to realize the power of the four motors to combine and improve the power density. The intermediate shaft transmits the combined power to the transmission mechanism. The transmission mechanism utilizes the large speed ratio of the planetary gear set to effectively improve the torque, and achieves multi-gear power output by controlling the first brake, the second brake and the clutch assembly, forming an effective match from low speed and high torque to high speed and low energy consumption, and improving the speed range bandwidth. By incorporating a clutch assembly and brake in the planetary gear set to achieve gear shifting, the system's axial dimension is avoided from being increased by gear settings, and the impact of parallel shaft shifting is also avoided, thus improving shifting smoothness and efficiency. The combination of the parallel shaft structure coupling assembly and the dual planetary gear set transmission mechanism not only improves the coupling efficiency between the motor and the transmission mechanism, but also enhances structural compactness, reduces the system's axial dimension, and is beneficial for overall vehicle layout. In the event of a single motor failure, the system's power output can still be maintained by the remaining motor and the appropriate gear, significantly enhancing the system's robustness. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the transmission structure of the four-motor four-speed composite transmission system integrated system in a specific implementation.

[0015] Figure 2 A schematic diagram of the transmission structure of a four-motor, four-speed composite transmission system for forming a single-speed power transmission.

[0016] Figure 3 A schematic diagram of the transmission structure of a four-motor, four-speed composite transmission system for forming a two-speed powertrain.

[0017] Figure 4 A schematic diagram of the transmission structure of a four-motor, four-speed composite transmission system for forming a three-speed powertrain.

[0018] Figure 5 A schematic diagram of the transmission structure of a four-motor, four-speed composite transmission system integrated with a four-speed powertrain. Detailed Implementation

[0019] The following is combined Figures 1-5 The embodiments of the present invention will be described in detail below.

[0020] The four-motor four-speed composite transmission integrated system includes a coupling component 1 for coupling the power of two motors, an intermediate shaft 2, a transmission mechanism 3 with four-speed function, and an output shaft 4. The coupling component 1 consists of two sets, which are symmetrically distributed on both sides of the intermediate shaft 2 and respectively mesh with the intermediate shaft 2. The transmission mechanism 3 includes a first planetary gear set 5 and a second planetary gear set 6 coaxially arranged behind the first planetary gear set 5. The intermediate shaft 2 is coaxially connected to the sun gear of the first planetary gear set 5. The output shaft 4 is mounted on the ring gear of the second planetary gear set 6. The ring gear of the first planetary gear set 5 is fixedly connected to the sun gear of the second planetary gear set 6. The ring gear of the second planetary gear set 6 contains a clutch assembly 7. The planet carrier of the first planetary gear set 5 is connected to the planet carrier or ring gear of the second planetary gear set 6 as the clutch assembly 7 moves. The ring gear of the first planetary gear set 5 is equipped with a first brake 8, and the planet carrier of the second planetary gear set 6 is equipped with a second brake 9.

[0021] The four-motor, four-speed composite transmission system described above integrates two motors via coupling component 1. The power from the two sets of coupling components 1 is coupled to the intermediate shaft 4, achieving power convergence of the four motors and increasing power density. The intermediate shaft 4 transmits the converged power to the transmission mechanism 3. The transmission mechanism 3 utilizes the large speed ratio of the planetary gear set to effectively increase torque. By controlling the first brake, the second brake, and the clutch assembly, it achieves multi-gear power output, forming an effective match from low-speed high torque to high-speed low energy consumption, thus increasing the speed range bandwidth. The clutch assembly 7 and brake are set in the planetary gear set to achieve gear shifting, which avoids increasing the axial dimension of the system due to gear settings and avoids the impact of parallel shaft shifting, improving shifting smoothness and efficiency. The combination of the parallel shaft structure coupling component and the double planetary gear set transmission mechanism not only improves the coupling efficiency between the motor and the transmission mechanism but also improves structural compactness, reduces the axial dimension of the system, and is beneficial for vehicle layout. In the event of a single motor failure, the system's power output can still be maintained by the remaining motor and the appropriate gear, significantly enhancing the system's robustness.

[0022] The coupling assembly 1 includes two motors 11, an input shaft 12 connected to the motor shaft ends, and a constantly meshing shaft 13 meshing with the input shaft 12. The constantly meshing shaft 13 meshes with the intermediate shaft 2. The meshing of the input shaft 12 with the constantly meshing shaft 13 couples the power of the two motors to the constantly meshing shaft 13. The meshing of the constantly meshing shaft 13 with the intermediate shaft 2 couples the power of the two sets of coupling assemblies 1 to the intermediate shaft 2, and the intermediate shaft 2 transmits the power to the sun gear of the first planetary gear set 3.

[0023] The first planetary gear set 5 includes a first sun gear 51 coaxially connected to the intermediate shaft 2, a first planet gear meshing with the first sun gear 51, a first planet carrier 52 mounted on the first planet gear, and a first gear ring 53 with an inner ring meshing with the first planet gear. The second planetary gear set 6 includes a second sun gear 61, a second planet gear meshing with the second sun gear 61, a second planet carrier 62 mounted on the second planet gear, and a second gear ring 63 with an inner ring meshing with the second planet gear. The output shaft 4 is mounted on the second gear ring 63. The first gear ring 53 is fixedly connected to the second sun gear 61. The first planet carrier 52 is connected to the second planet carrier 62 or the second gear ring 63 as the clutch assembly 7 moves. The first brake 8 is mounted on the first gear ring 53, and the second brake 9 is mounted on the second planet carrier 52. When the first brake 8 is activated, the first ring gear 53 is fixed; when the second brake is activated, the second planetary carrier 52 is fixed. When the first brake 8 is activated and the clutch assembly 7 moves to connect the first planetary carrier 52 with the second ring gear 63, the power of the two sets of coupling assemblies 1 is transmitted to the intermediate shaft 2. The intermediate shaft 2 drives the first sun gear 51 to rotate. Part of the power of the first sun gear 51 is transmitted to the output shaft 4 via the first planetary carrier 52 and the second ring gear 63, and the other part of the power is transmitted to the output shaft 4 via the first ring gear 53, the second sun gear 61, and the second ring gear 63. On shaft 4, the two power sources converge to form first-gear power output. First-gear power has high torque and low speed, meeting the driving requirements of low-speed, high-torque operation, suitable for heavy-load climbing or muddy conditions. When the second brake 9 is activated, the clutch assembly 7 connects the first planetary carrier 52 and the second planetary carrier 62. The power of the two sets of coupling assemblies 1 is transmitted to the intermediate shaft 2. The intermediate shaft 2 drives the first sun gear 51 to rotate. The power of the first sun gear 51 passes through the first ring gear 53, the second sun gear 61, and the second ring gear 63 to the output shaft 4, forming second-gear power output. The torque of second-gear power is lower than that of first-gear power, but the speed is higher. Second-gear power is suitable for heavy-load, flat-road conditions. When the first brake 8 is activated, the clutch assembly 7 connects the first planetary carrier 52 and the second ring gear 63. The power of the two sets of coupling assemblies 1 is transmitted to the intermediate shaft 2. The intermediate shaft 2 drives the first sun gear 51 to rotate. The power of the first sun gear 51 is transmitted to the output shaft 4 through the first planetary carrier 52 and the second ring gear 53, forming third-gear power output. The torque of third-gear power is lower than that of second-gear power, but the speed is higher. Third-gear power is suitable for... For light-load uphill or muddy conditions; when the first brake 8 is activated, the clutch assembly 7 moves to connect the first planetary carrier 52 and the second planetary carrier 62, the power of the two sets of coupling assemblies 1 is transmitted to the intermediate shaft 2, the intermediate shaft 2 drives the first sun gear 51 to rotate, and the power of the first sun gear 51 is transmitted to the output shaft 4 through the first planetary carrier 52, the second planetary carrier 62, and the second ring gear 63, forming a four-speed power output. The torque of the fourth-speed power is lower than that of the third-speed power, and the speed is higher than that of the third-speed power. The fourth-speed power is suitable for light-load flat road conditions and meets the driving requirements of high speed and low energy consumption.

[0024] The first planetary carrier 52 has a fixed engagement gear 54 at its output end. The clutch assembly 7 includes a first clutch 71 that connects the engagement gear 54 to the second planetary carrier 62 and a second clutch 72 that connects the engagement gear 54 to the second gear ring 63. The engagement gear 54 is fixed to the first planetary carrier 52. When the first clutch 71 is engaged, the engagement gear 54 is connected to the second planetary carrier 62, forming a connection between the first planetary carrier 52 and the second planetary carrier 62. When the second clutch 72 is engaged, the engagement gear 54 is connected to the second gear ring 63, forming a connection between the first planetary carrier 52 and the second gear ring 63.

[0025] The first ring gear 53 and the first sun gear 51 are integrally formed. The output end of the first planetary carrier 52 passes through the first ring gear 53 and the second sun gear 61 and extends into the second ring gear 63. A support gear 64 corresponding to the engaging gear 54 is fixed on the second ring gear 63. A first clutch 71 is installed between the second planetary carrier 62 and the engaging gear 54, and a second clutch 72 is installed between the engaging gear 54 and the support gear 64. As can be seen from the attached drawings, the first clutch 71 is located between the second planetary carrier 62 and the engaging gear 54. When the first clutch 71 is engaged, it connects the second planetary carrier 62 and the engaging gear 54, forming a connection between the first planetary carrier 52 and the second planetary carrier 62. The second clutch 72 is located between the engaging gear 54 and the support gear 64. When the second clutch 72 is engaged, the engaging gear 54 and the support gear 64 are connected, forming a connection between the first planetary carrier 52 and the second ring gear 63.

[0026] The first clutch 71 is a sliding sleeve mounted on the second planetary carrier 62, which can slide axially. The first clutch 71 slides to the right on the second planetary carrier 62 and engages with the engagement gear 54. The second clutch 72 is a sliding sleeve mounted on the support gear 64, which can slide to the left on the support gear 64 and engages with the engagement gear 54. The engagement gear 54 is located between the second planetary carrier 62 and the second ring gear 63. The movement of the first clutch 71 or the second clutch 72 can form a connection between the first planetary carrier 52 and the second planetary carrier 62 or the second ring gear 63. Both the first clutch 71 and the second clutch 72 are sliding sleeve type clutches, and the engagement and disengagement of the clutches are achieved by the sliding of the sliding sleeves. The structure is simple and easy to operate.

[0027] This invention also protects the speed control method of the above-described four-motor four-speed composite transmission integrated system. The four-speed power of the four-motor four-speed composite transmission system is formed by controlling the clutch assembly 7, the first brake 8, and the second brake 9. The characteristic feature is that the control method from first gear to fourth gear is as follows: When the first brake is engaged, the clutch assembly 7 moves to connect the planet carrier of the first planetary gear set 5 with the ring gear of the second planetary gear set 6, forming the first gear. When the second brake is engaged, the clutch assembly 7 moves to connect the planet carrier of the first planetary gear set 5 with the planet carrier of the second planetary gear set 6, forming second gear power; When the first brake is engaged, the clutch assembly 7 moves to connect the planet carrier of the first planetary gear set 5 with the ring gear of the second planetary gear set, forming a three-speed power. When the first brake is engaged, the clutch assembly 7 moves to connect the planet carrier of the first planetary gear set with the planet carrier of the second planetary gear set, forming a fourth-speed power.

[0028] When the first brake is activated and the clutch assembly 7 moves to connect the first planetary carrier 52 and the second ring gear 63, the power of the two sets of coupling assemblies 1 is transmitted to the intermediate shaft 2. The intermediate shaft 2 drives the first sun gear 51 to rotate. Part of the power from the first sun gear 51 is transmitted to the output shaft 4 via the first planetary carrier 52 and the second ring gear 63, while the other part of the power is transmitted to the output shaft 4 via the first ring gear 53, the second sun gear 61, and the second ring gear 63. The two parts of the power converge on the output shaft 4, forming a first-gear power output. With high torque and low speed, it meets the driving requirements of low-speed, high-torque operation and is suitable for heavy-load climbing or muddy conditions. When the second brake 9 is activated, the clutch assembly 7 connects the first planetary carrier 52 and the second planetary carrier 62. The power of the two sets of coupling assemblies 1 is transmitted to the intermediate shaft 2. The intermediate shaft 2 drives the first sun gear 51 to rotate. The power of the first sun gear 51 is transmitted through the first ring gear 53, the second sun gear 61, and the second ring gear 63 to the output shaft 4, forming a second-gear power output. The torque of the second-gear power is lower than that of the first-gear power, and the speed is higher than that of the first-gear power. The first gear is suitable for heavy-duty flat road conditions. When the first brake 8 is activated, the clutch assembly 7 moves to connect the first planetary carrier 52 and the second ring gear 63. The power of the two sets of coupling assemblies 1 is transmitted to the intermediate shaft 2. The intermediate shaft 2 drives the first sun gear 51 to rotate. The power of the first sun gear 51 is transmitted to the output shaft 4 through the first planetary carrier 52 and the second ring gear 53, forming the third gear power output. The torque of the third gear power is lower than that of the second gear power, and the speed is higher than that of the second gear power. The third gear power is suitable for light-duty climbing or muddy conditions. When the first brake 8 is activated, the clutch assembly 7 moves to connect the first planetary carrier 52 and the second planetary carrier 62. The power of the two sets of coupling assemblies 1 is transmitted to the intermediate shaft 2. The intermediate shaft 2 drives the first sun gear 51 to rotate. The power of the first sun gear 51 is transmitted to the output shaft 4 through the first planetary carrier 52, the second planetary carrier 62, and the second ring gear 63, forming a four-speed power output. The torque of the fourth-speed power is lower than that of the third-speed power, but the speed is higher than that of the third-speed power. The fourth-speed power is suitable for light-load flat road conditions and meets the drive requirements of high speed and low energy consumption.

[0029] in, "The movement of clutch assembly 7 connects the planet carrier of the first planetary set 5 with the ring gear of the second planetary set 6" means that the second clutch 72 slides to the left on the support gear 64 and engages with the engagement gear 54; the second clutch 72 engages the support gear 64 and the engagement gear 54, forming a connection between the first planetary carrier 52 and the second ring gear 63; "The movement of clutch assembly 7 connects the planet carrier of the first planetary set 5 with the planet carrier of the second planetary set 6" means that the first clutch 71 slides to the right on the second planetary carrier 62 and engages with the engagement gear 54; the first clutch 71 engages the second planetary carrier and the engagement gear 54, forming a connection between the second planetary carrier 62 and the first planetary carrier 52. The engagement gear 54 is located between the second planetary carrier 62 and the second ring gear 63. The movement of the first clutch 71 or the second clutch 72 can form a connection between the first planetary carrier 52 and the second planetary carrier 62 or the second ring gear 63. Both the first clutch 71 and the second clutch 72 are sliding sleeve type clutches. The engagement and disengagement of the clutch are achieved by the sliding of the sliding sleeve. The structure is simple and easy to operate.

[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 four-motor four-speed composite transmission integrated system, comprising a coupling assembly for coupling the power of two motors, an intermediate shaft, a transmission mechanism with four-speed function, and an output shaft, wherein the number of coupling assemblies is two sets, the two sets of coupling assemblies are symmetrically distributed on both sides of the intermediate shaft and respectively mesh with the intermediate shaft, characterized in that: The transmission mechanism includes a first planetary gear set and a second planetary gear set coaxially arranged behind the first planetary gear set. An intermediate shaft is coaxially connected to the sun gear of the first planetary gear set. An output shaft is mounted on the ring gear of the second planetary gear set. The ring gear of the first planetary gear set is fixedly connected to the sun gear of the second planetary gear set. A clutch assembly is installed inside the ring gear of the second planetary gear set. The planet carrier of the first planetary gear set is connected to the planet carrier or ring gear of the second planetary gear set as the clutch assembly moves. A first brake is installed on the ring gear of the first planetary gear set, and a second brake is installed on the planet carrier of the second planetary gear set. The first planetary gear set includes a first sun gear coaxially connected to the intermediate 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 output shaft is mounted on the second gear ring. The first gear ring is fixedly connected to the second sun gear. The first planet carrier is connected to the second planet carrier or the second gear ring as the clutch assembly moves. The first brake is mounted on the first gear ring, and the second brake is mounted on the second planet carrier. The output end of the first planetary carrier is fixed to the engagement gear, and the clutch assembly includes a first clutch that can connect the engagement gear to the second planetary carrier and a second clutch that can connect the engagement gear to the second gear ring. The first gear ring and the first sun gear are integrally formed. The output end of the first planetary carrier passes through the first gear ring and the second sun gear and extends into the second gear ring. A support gear corresponding to the engaging gear is fixed on the second gear ring. The first clutch is installed between the second planetary carrier and the engaging gear, and the second clutch is installed between the engaging gear and the support gear. The first clutch is a sliding gear sleeve that can slide axially on the second planetary carrier. The first clutch slides to the right on the second planetary carrier and engages with the engagement gear. The second clutch is a sliding gear sleeve that can slide axially on the support gear. The second clutch slides to the left on the support gear and engages with the engagement gear.

2. The four-motor four-speed composite transmission integrated system according to claim 1, characterized in that: The coupling assembly includes two motors, an input shaft connected to the motor shaft ends respectively, and a normally meshed shaft meshing with the input shaft. The normally meshed shaft meshes with an intermediate shaft.

3. The speed control method for the four-motor, four-speed composite transmission integrated system according to any one of claims 1 to 2, The four-speed powertrain of the four-motor four-speed composite transmission system is formed by controlling the clutch assembly, the first brake, and the second brake. Its characteristics are: The control method for power from first gear to fourth gear is as follows: When the second brake is engaged, the clutch assembly moves to connect the planet carrier of the first planetary gear set with the ring gear of the second planetary gear set, forming the first gear. When the second brake is engaged, the clutch assembly moves to connect the planet carrier of the first planetary gear set with the planet carrier of the second planetary gear set, forming second gear power; When the first brake is engaged, the clutch assembly moves to connect the planet carrier of the first planetary gear set with the ring gear of the second planetary gear set, forming a three-speed power. When the first brake is engaged, the clutch assembly moves to connect the planet carrier of the first planetary gear set with the planet carrier of the second planetary gear set, forming a fourth gear.

4. The speed control method for the four-motor, four-speed composite transmission integrated system according to claim 3, characterized in that: "The movement of the clutch assembly connects the planet carrier of the first planetary gear set with the ring gear of the second planetary gear set" means that the second clutch slides to the left on the support gear and engages with the engagement gear; "The movement of the clutch assembly connects the planet carrier of the first planetary gear set with the planet carrier of the second planetary gear set" means that the first clutch slides to the right on the second planetary carrier and engages with the engagement gear.

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