Four-motor four-gear composite transmission speed changer integrated system and speed change control method thereof

Abstract

According to the four-motor four-gear composite transmission speed changer integrated system, the characteristic that the speed ratio of a planet row is large is utilized, the torque is effectively increased, multi-gear power output is achieved by controlling the first brake, the second brake and the clutch assembly, effective matching from low-speed large torque to high-speed low energy consumption is formed, and the speed domain bandwidth is increased; a clutch assembly and a brake are arranged in a planet row to achieve gear shifting, gear setting is prevented from increasing the axial size of a system, parallel shaft gear shifting impact is avoided, gear shifting smoothness and efficiency are improved, a coupling assembly of a parallel shaft structure is combined with a speed change mechanism of a double-planet-row structure, the coupling efficiency of a motor and the speed change mechanism is improved, and the service life of the motor is prolonged. The structure compactness is improved, the axial size of the system is reduced, and arrangement of the whole vehicle is facilitated; when a single motor breaks down, power output of the system can still be maintained through the remaining motors and the adaptive gear, and the robustness of the system is remarkably enhanced. The invention further provides a variable speed control method of the four-motor four-gear composite transmission integrated system.

Description

Technical Field

[0001] The present invention relates to a four-motor four-speed compound transmission integrated system and a speed control method thereof, belonging to the technical field of pure electric transmissions. Background Art

[0002] As electric vehicles continue to demand high-efficiency, multi-scenario power output, traditional single-speed electric drive systems, due to their fixed transmission ratios, struggle to balance low-speed torque with high-speed energy efficiency. To enhance power flexibility, pure electric transmissions have developed a drive technology that uses multiple motors in coordinated, multi-speed shifting. Multi-speed shifting technology has become a key approach to improving the overall performance of electric drive systems. Existing electric drive transmissions often utilize planetary gears and parallel shaft structures. The planetary gear increases speed ratios and output torque, while the parallel shaft structure creates a shifting transmission. However, the parallel shaft structure suffers from shift shock, power interruption, insufficient gear scalability, and low gear shift efficiency. Furthermore, the multiple gear pull configuration in the parallel shaft structure creates structural redundancy, increases the axial space of the transmission, and is detrimental to vehicle layout.

[0003] In addition, although the driving technology of multiple motors coordinated with multi-speed shifting can improve power flexibility, the coupling efficiency between the motor and the speed shifting mechanism is low. Summary of the Invention

[0004] The four-motor, four-speed compound transmission integrated system provided by this invention effectively matches low-speed, high-torque transmissions to high-speed, low-energy transmissions, increasing speed bandwidth and enhancing smooth and efficient shifting. This not only improves the coupling efficiency between the motor and the transmission mechanism, but also enhances structural compactness, reduces the system's axial dimensions, facilitates overall vehicle layout, and significantly enhances system robustness. The invention also provides a speed control method for the four-motor, four-speed compound transmission integrated system.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is: A four-motor four-speed compound transmission integrated system includes a coupling assembly for coupling the power of two motors, an intermediate shaft, a speed change mechanism with a four-speed shifting function, and an output shaft. The number of coupling assemblies is two groups, and the two groups of coupling assemblies are symmetrically distributed on both sides of the intermediate shaft and respectively mesh with the intermediate shaft. It is characterized in that: the speed change mechanism includes a first planetary row and a second planetary row coaxially arranged on the rear side of the first planetary row, the intermediate shaft is coaxially connected to the sun gear of the first planetary row, the output shaft is assembled on the ring gear of the second planetary row, the ring gear of the first planetary row is fixedly connected to the sun gear of the second planetary row, the ring gear of the second planetary row is equipped with a clutch assembly, the planet carrier of the first planetary row is connected to the planet carrier or ring gear of the second planetary row as the clutch assembly moves, the ring gear of the first planetary row is equipped with a first brake, and the planet carrier of the second planetary row is equipped with a second brake.

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

[0007] Preferably, the first planetary row includes a first sun gear coaxially connected to the intermediate shaft, a first planetary gear meshed with the first sun gear, a first planetary carrier mounted on the first planetary gear, and a first ring gear whose inner ring is meshed with the first planetary gear; the second planetary row includes a second sun gear, a second planetary gear meshed with the second sun gear, a second planetary carrier mounted on the second planetary gear, and a second ring gear whose inner ring is meshed with the second planetary gear; the output shaft is mounted on the second ring gear, the first ring gear is fixedly connected to the second sun gear, the first planetary carrier is connected to the second planetary carrier or the second ring gear as the clutch assembly moves, the first brake is mounted on the first ring gear, and the second brake is mounted on the second planetary carrier.

[0008] Preferably, the output end of the first planetary carrier is fixedly coupled to a gear, and the clutch assembly comprises a first clutch capable of connecting the coupled gear to the second planetary carrier and a second clutch capable of connecting the coupled gear to the second ring gear.

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

[0010] Preferably, the first clutch is a sliding gear sleeve mounted on the second planetary carrier and can slide axially, the first clutch slides to the right on the second planetary carrier and is combined with the coupling gear, and the second clutch is a sliding gear sleeve mounted on the supporting gear and can slide axially, the second clutch slides to the left on the supporting gear and is combined with the coupling gear.

[0011] The above-mentioned speed control method of the four-motor four-speed compound transmission integrated system is By controlling the clutch assembly, the first brake and the second brake, a four-speed power of a four-motor four-speed compound transmission integrated system is formed, characterized in that: the control method from the first speed power to the fourth speed power is as follows: When the first brake is activated, 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 power; When the second brake is activated, the clutch assembly moves to connect the planet carrier of the first planetary gear with the planet carrier of the second planetary gear, forming the second gear power; When the first brake is activated, the clutch assembly moves to connect the planetary carrier of the first planetary gear set with the ring gear of the second planetary gear set, forming the third gear power; When the first brake is activated, the clutch assembly moves to connect the planet carrier of the first planetary gear with the planet carrier of the second planetary gear, forming the fourth gear power.

[0012] Preferably, “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” means that the second clutch slides to the left on the support gear and engages with the coupling gear; “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” means that the first clutch slides to the right on the second planetary gear set and engages with the coupling gear.

[0013] The beneficial effects of the present invention are: The four-motor, four-speed compound transmission integrated system of the present invention has a coupling assembly that couples the power of the two motors. The power of the two sets of coupling assemblies is coupled to the intermediate shaft, realizing the power confluence of the four motors and improving the power density. The intermediate shaft transmits the confluence power to the speed change mechanism. The speed change mechanism utilizes the large speed ratio of the planetary gear to effectively improve the torque, and realizes multi-speed 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, thereby improving the speed range bandwidth. Setting a clutch assembly and a brake in the planetary gearbox to achieve gear shifting not only avoids the gear setting from increasing the axial size of the system, but also avoids the impact of parallel shaft gear shifting, thereby improving the smoothness and efficiency of gear shifting. The coupling assembly of the parallel shaft structure is combined with the speed change mechanism of the double planetary gearbox structure, which not only improves the coupling efficiency of the motor and the speed change mechanism, but also improves the structural compactness, reduces the axial size of the system, and is beneficial to the overall vehicle layout. In the event of a single motor failure, the system's power output can still be maintained through the remaining motors and the adapted gear, significantly enhancing the system's robustness. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a transmission structure diagram of a four-motor four-speed compound transmission integrated system in a specific implementation method.

[0015] Figure 2 Schematic diagram of the transmission structure of the four-motor four-speed compound transmission integrated system when forming first-gear power.

[0016] Figure 3 Schematic diagram of the transmission structure of the four-motor four-speed compound transmission integrated system when forming second-gear power.

[0017] Figure 4 Schematic diagram of the transmission structure of the four-motor four-speed compound transmission integrated system when forming three-speed power.

[0018] Figure 5 Schematic diagram of the transmission structure of the four-motor four-speed compound transmission integrated system to form four-speed power. DETAILED DESCRIPTION

[0019] The following combination Figures 1 to 5 The embodiments of the present invention are described in detail.

[0020] A four-motor four-speed compound transmission integrated system includes a coupling assembly 1 for coupling the power of two motors, an intermediate shaft 2, a speed change mechanism 3 with a four-speed shifting function, and an output shaft 4. The number of coupling assemblies 1 is two groups, and the two groups of coupling assemblies 1 are symmetrically distributed on both sides of the intermediate shaft 2 and respectively mesh with the intermediate shaft 2. It is characterized in that the speed change mechanism 3 includes a first planetary row 5 and a second planetary row 6 coaxially arranged behind the first planetary row 5. The intermediate shaft 2 is coaxially connected to the sun gear of the first planetary row 5. The output shaft 4 is assembled on the ring gear of the second planetary row 6. The ring gear of the first planetary row 5 is fixedly connected to the sun gear of the second planetary row 6. A clutch assembly 7 is installed in the ring gear of the second planetary row 6. The planet carrier of the first planetary row 5 is connected to the planet carrier or ring gear of the second planetary row 6 as the clutch assembly 7 moves. A first brake 8 is installed on the ring gear of the first planetary row 5, and a second brake 9 is installed on the planet carrier of the second planetary row 6.

[0021] In the aforementioned four-motor, four-speed compound transmission integrated system, coupling assembly 1 couples the power of two motors. The power of the two coupling assemblies 1 is coupled to the intermediate shaft 4, achieving power confluence of the four motors and improving power density. The intermediate shaft 4 transmits the confluence 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, multi-gear power output is achieved, forming an effective match from low-speed, high-torque to high-speed, low-energy consumption, thereby increasing the speed bandwidth. The clutch assembly 7 and brake are provided in the planetary gear set to achieve gear shifting, which not only avoids the increase in the axial size of the system due to the gear setting, but also avoids the shock of parallel shaft gear shifting, thereby improving smooth and efficient gear shifting. The combination of the parallel shaft coupling assembly and the dual planetary gear gear transmission mechanism not only improves the coupling efficiency between the motor and the gear transmission mechanism, but also improves the structural compactness, reduces the axial size of the system, and facilitates the overall vehicle layout. In the event of a single motor failure, the system's power output can still be maintained through the remaining motors and the adapted gear, significantly enhancing the system's robustness.

[0022] The coupling assembly 1 comprises two motors 11, input shafts 12 connected to the shaft ends of each motor, and constant meshing shafts 13 meshing with the input shafts 12. The constant meshing shafts 13 mesh with the intermediate shaft 2. The input shafts 12 mesh with the constant meshing shafts 13, coupling the power of the two motors to the constant meshing shafts 13. The meshing of the constant meshing shafts 13 with the intermediate shaft 2 couples the power of the two coupling assemblies 1 to the intermediate shaft 2, which then transmits the power to the sun gear of the first planetary gear set 3.

[0023] Among them, the first planetary row 5 includes a first sun gear 51 coaxially connected to the intermediate shaft 2, a first planetary gear meshed with the first sun gear 51, a first planetary carrier 52 mounted on the first planetary gear, and a first ring gear 53 whose inner ring is meshed with the first planetary gear. The second planetary row 6 includes a second sun gear 61, a second planetary gear meshed with the second sun gear 61, a second planetary carrier 62 mounted on the second planetary gear, and a second ring gear 63 whose inner ring is meshed with the second planetary gear. The output shaft 4 is mounted on the second ring gear 63, the first ring gear 53 is fixedly connected to the second sun gear 61, and the first planetary carrier 52 is connected to the second planetary carrier 62 or the second ring gear 63 as the clutch assembly 7 moves. The first brake 8 is mounted on the first ring gear 53, and the second brake 9 is mounted on the second planetary carrier 52. When the first brake 8 is activated, the first ring gear 53 is fixed, and 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, and 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 by driving 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 through the first ring gear 53, the second sun gear 61 and the second ring gear 63. The two parts of power converge on the output shaft 4 to form the first gear power output. The first gear power has large torque and low speed, which meets the driving requirements of low speed and high torque and is suitable for heavy-load climbing or muddy conditions. When the second brake 9 is activated and the clutch assembly 7 connects the first planetary carrier 52 with the second planetary carrier 62, the power of the two sets of coupling assemblies 1 is transmitted to the intermediate shaft 2, and 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 ring gear 53, the second sun gear 61, and the second ring gear 63, forming the 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 second gear power is suitable for heavy-load flat road conditions; when the first brake 8 is activated, the clutch assembly 7 moves to connect the first planetary carrier 52 with the second ring gear 63, and the power of the two sets of coupling assemblies 1 is transmitted to the intermediate shaft 2, and 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 a 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 load climbing or muddy working conditions; when the first brake 8 is activated and the clutch assembly 7 moves to connect the first planetary carrier 52 with the second planetary carrier 62, the power of the two sets of coupling assemblies 1 is transmitted to the intermediate shaft 2, and 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 fourth-gear power output. The torque of the fourth-gear power is lower than that of the third-gear power, and the speed is higher than that of the third-gear power. The fourth-gear power is suitable for light-load flat road conditions and meets the driving requirements of high speed and low energy consumption.

[0024] The output end of the first planetary carrier 52 is fixed to a coupling gear 54, and the clutch assembly 7 includes a first clutch 71 that can connect the coupling gear 54 to the second planetary carrier 62, and a second clutch 72 that can connect the coupling gear 54 to the second ring gear 63. The coupling gear 54 is fixed to the first planetary carrier 52. When the first clutch 71 is engaged, the coupling 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 coupling gear 54 is connected to the second ring gear 63, forming a connection between the first planetary carrier 52 and the second planetary carrier 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 extends through the first ring gear 53 and the second sun gear 61 and into the second ring gear 63. A support gear 64 corresponding to the coupling gear 54 is fixed to the second ring gear 63. The first clutch 71 is installed between the second planetary carrier 62 and the coupling gear 54, and the second clutch 72 is installed between the coupling gear 54 and the support gear 64. As can be seen from the accompanying drawings, the first clutch 71 is arranged between the second planetary carrier 62 and the coupling gear 54. When the first clutch 71 is engaged, the second planetary carrier 62 is connected to the coupling gear 54, forming a connection between the first planetary carrier 52 and the second planetary carrier 62. The second clutch 72 is arranged between the coupling gear 54 and the support gear 64. When the second clutch 72 is engaged, the coupling gear 54 is connected to the support gear 64, forming a connection between the first planetary carrier 52 and the second ring gear 63.

[0026] The first clutch 71 is a sliding gear sleeve mounted on the second planetary carrier 62 and slidable in the axial direction. The first clutch 71 slides rightward on the second planetary carrier 62 to engage with the coupling gear 54. The second clutch 72 is a sliding gear sleeve mounted on the support gear 64 and slidable in the axial direction. The second clutch 72 slides leftward on the support gear 64 to engage with the coupling gear 54. The coupling gear 54 is disposed between the second planetary carrier 62 and the second ring gear 63. The movement of the first clutch 71 or the second clutch 72 forms 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 gear sleeve clutches. The engagement and disengagement of the clutches are achieved by sliding of the sliding gear sleeve. They have a simple structure and are easy to operate.

[0027] The present invention also protects the speed control method of the above-mentioned four-motor four-speed compound transmission integrated system, By controlling the clutch assembly 7, the first brake 8 and the second brake 9, a four-speed power of the four-motor four-speed compound transmission integrated system is formed, which is characterized in that the control method from the first gear power to the fourth gear power is as follows: When the first brake is activated, the clutch assembly 7 moves to connect the planet carrier of the first planetary gear 5 with the ring gear of the second planetary gear 6, forming the first gear power; When the second brake is activated, the clutch assembly 7 moves to connect the planet carrier of the first planetary gear 5 with the planet carrier of the second planetary gear 6, thus forming the second gear power; When the first brake is activated, the clutch assembly 7 moves to connect the planet carrier of the first planetary gear 5 with the ring gear of the second planetary gear, forming the third gear power; When the first brake is activated, 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 gear power.

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

[0029] in, “The movement of the clutch assembly 7 to connect the planet carrier of the first planetary gear 5 with the ring gear of the second planetary gear 6” means that the second clutch 72 slides to the left on the supporting gear 64 and engages with the coupling gear 54; the second clutch 72 engages the supporting gear 64 with the coupling gear 54, forming a connection between the first planetary gear 52 and the second ring gear 63; “The movement of the clutch assembly 7 to connect the planet carrier of the first planetary gear 5 with the planet carrier of the second planetary gear 6” means that the first clutch 71 slides to the right on the second planetary gear 62 and engages with the coupling gear 54; the first clutch 71 engages the second planetary gear 54 with the coupling gear 54, forming a connection between the second planetary gear 62 and the first planetary gear 52. The coupling gear 54 is arranged between the second planetary gear 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 gear 52 and the second planetary gear 62 or the second ring gear 63. The first clutch 71 and the second clutch 72 are both sliding gear sleeve type clutches. The clutch is engaged and disengaged by sliding the sliding gear sleeve. They have a simple structure and are easy to operate.

[0030] The above fully describes the technical solutions of the embodiments of the present invention in conjunction with the accompanying drawings. It should be noted that the embodiments described are only part of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

Claims

1. A four-motor, four-speed compound transmission integrated system includes a coupling assembly for coupling the power of the two motors, an intermediate shaft, a speed change mechanism with four-speed shifting capability, and an output shaft. The system comprises two sets of coupling assemblies, symmetrically distributed on either side of the intermediate shaft and meshing with the intermediate shaft. The system is characterized by: The speed change mechanism includes a first planetary row and a second planetary row coaxially arranged on the rear side of the first planetary row. The intermediate shaft is coaxially connected to the sun gear of the first planetary row, and the output shaft is assembled on the ring gear of the second planetary row. The ring gear of the first planetary row is fixedly connected to the sun gear of the second planetary row. A clutch assembly is installed in the ring gear of the second planetary row. The planet carrier of the first planetary row is connected to the planet carrier or ring gear of the second planetary row with the movement of the clutch assembly. A first brake is installed on the ring gear of the first planetary row, and a second brake is installed on the planet carrier of the second planetary row.

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

3. The four-motor four-speed compound transmission integrated system according to claim 1, characterized in that: The first planetary row includes a first sun gear coaxially connected to the intermediate shaft, a first planetary gear meshed with the first sun gear, a first planetary carrier mounted on the first planetary gear, and a first ring gear whose inner ring is meshed with the first planetary gear. The second planetary row includes a second sun gear, a second planetary gear meshed with the second sun gear, a second planetary carrier mounted on the second planetary gear, and a second ring gear whose inner ring is meshed with the second planetary gear. The output shaft is mounted on the second ring gear, the first ring gear is fixedly connected to the second sun gear, the first planetary carrier is connected to the second planetary carrier or the second ring gear as the clutch assembly moves, the first brake is mounted on the first ring gear, and the second brake is mounted on the second planetary carrier.

4. The four-motor four-speed compound transmission integrated system according to claim 3, characterized in that: The output end of the first planetary carrier is fixed with a coupling gear, and the clutch assembly includes a first clutch that can connect the coupling gear with the second planetary carrier and a second clutch that can connect the coupling gear with the second ring gear.

5. The four-motor four-speed compound transmission integrated system according to claim 4, characterized in that: The first ring gear and the first sun gear are integrally formed, the output end of the first planetary carrier passes through the first ring gear and the second sun gear and extends into the second ring gear, a supporting gear corresponding to the coupling gear is fixed on the second ring gear, the first clutch is installed between the second planetary carrier and the coupling gear, and the second clutch is installed between the coupling gear and the supporting gear.

6. The four-motor four-speed compound transmission integrated system according to claim 5, characterized in that: The first clutch is a sliding gear sleeve mounted on the second planetary carrier and can slide axially. The first clutch slides to the right on the second planetary carrier and is engaged with the coupling gear. The second clutch is a sliding gear sleeve mounted on the supporting gear and can slide axially. The second clutch slides to the left on the supporting gear and is engaged with the coupling gear.

7. The speed control method of the four-motor four-speed compound transmission integrated system according to any one of claims 1 to 6, The four-speed power of the four-motor four-speed compound transmission integrated system is formed by controlling the clutch assembly, the first brake and the second brake, and is characterized by: The control method from the first gear to the fourth gear is: When the first brake is activated, 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 power; When the second brake is activated, the clutch assembly moves to connect the planet carrier of the first planetary gear with the planet carrier of the second planetary gear, forming the second gear power; When the first brake is activated, the clutch assembly moves to connect the planetary carrier of the first planetary gear set with the ring gear of the second planetary gear set, forming the third gear power; When the first brake is activated, the clutch assembly moves to connect the planet carrier of the first planetary gear with the planet carrier of the second planetary gear, forming the fourth gear power.

8. The speed control method of the four-motor four-speed compound transmission integrated system according to claim 7, characterized in that: "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" means that the second clutch slides to the left on the support gear and engages with the coupling gear; "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" means that the first clutch slides to the right on the second planetary gear set and engages with the coupling gear.

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