A coaxial dual-motor drive axle assembly and a working method thereof

Abstract

The application discloses a coaxial double-motor driving axle assembly structure and a working method thereof. The application has the distributed driving, single-motor driving and double-motor simultaneous driving modes. The differential package with the differential lock does not intervene in the work in the distributed driving mode, and intervenes in the work in the single-motor driving or double-motor simultaneous driving mode. When the wheels start to slip on the road surface with small adhesion, the differential package with the differential lock is automatically locked to ensure the passability of the vehicle. When the whole vehicle is high-speed sliding, the power of the whole vehicle can be cut off in real time according to the requirement, and the economy and the power performance of the whole vehicle are better balanced. The application has the structural characteristics of the distributed driving, single-motor driving, double-motor driving, coaxial type, planetary mechanism transmission, differential lock locking and power cutting.

Description

Technical Field

[0001] This invention relates to the field of electric drive axle technology, and in particular to a coaxial dual-motor drive axle assembly and its working method. Background Technology

[0002] Currently, most new energy electric drive axle systems on the market use a single motor parallel shaft and lack integrated differential locks and disconnection mechanisms. Power is mostly transmitted to each wheel via the drive shaft, and each wheel cannot perform independent vector control. This results in a lack of adaptability to complex road conditions, no independent axle disengagement function, and poor energy efficiency. These products, which fail to meet customer needs, have long power transmission routes, low efficiency, large size, and high energy consumption, and are no longer competitive in the market. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of the prior art and provide a coaxial dual-motor drive axle assembly and its working method, in which each wheel can be independently vector controlled, multiple power sources can be switched in real time according to energy consumption requirements, it has self-locking, can be disengaged, is highly integrated, and is miniaturized.

[0004] The objective of this invention is achieved as follows:

[0005] A coaxial dual-motor drive axle assembly, characterized in that it includes a left wheel, a left motor assembly, a left planetary transmission mechanism assembly, a left synchronizer, a left constant mesh gear, a needle roller bearing, a right constant mesh gear, a right synchronizer, a right planetary transmission mechanism assembly, a right motor assembly, a right wheel, a differential assembly, a left output inner shaft, and a right output inner shaft.

[0006] The left motor assembly includes a left motor rotor and a left motor stator, and the right motor assembly includes a right motor rotor and a right motor stator. The opposite ends of the left motor rotor and the right motor rotor are connected to a sun gear, and the left motor rotor and the right motor rotor have axial inner holes.

[0007] The left planetary transmission assembly includes left planetary gears, a left planetary carrier, and a left planetary ring gear. The left planetary ring gear has a clutch for self-braking. The left planetary gears are mounted on the left planetary carrier, which has a shaft portion loosely fitted inside the left motor rotor. The shaft portion of the left planetary carrier is connected to a left wheel. The left planetary gears mesh with the sun gear and the left planetary ring gear on the left motor rotor, respectively. The right planetary transmission assembly includes right planetary gears, a right planetary carrier, and a right planetary ring gear. The ring gear has a clutch for braking itself. The planetary gears of the right planetary transmission mechanism are mounted on the planetary carrier of the right planetary transmission mechanism. The planetary carrier of the right planetary transmission mechanism has a shaft that is loosely fitted inside the rotor of the right motor. The shaft of the planetary carrier of the right planetary transmission mechanism is connected to the right wheel. The planetary gears of the right planetary transmission mechanism mesh with the sun gear and the ring gear of the right planetary transmission mechanism on the rotor of the right motor respectively. One end of the shaft of the planetary gear of the left planetary transmission mechanism passes through the planetary carrier of the left planetary transmission mechanism and is connected to the left synchronizer. One end of the shaft of the planetary gear of the right planetary transmission mechanism passes through the planetary carrier of the right planetary transmission mechanism and is connected to the right synchronizer. The opposite ends of the planetary carriers of the left and right planetary transmission mechanisms are provided with synchronous engagement surfaces.

[0008] The differential assembly includes a differential lock and a main reduction gear. Both the left and right constant mesh gears mesh with the main reduction gear. The opposing ends of the left and right constant mesh gears have synchronous engagement surfaces. The left synchronizer is located between the synchronous engagement surfaces of the left planetary transmission mechanism's planet carrier and the left constant mesh gear. The right synchronizer is located between the synchronous engagement surfaces of the right planetary transmission mechanism's planet carrier and the right constant mesh gear. The left output inner shaft is loosely fitted inside the shaft portion of the left planetary transmission mechanism's planet carrier. One end of the left output inner shaft is connected to the left wheel, and the other end is connected to the differential assembly. The right output inner shaft is loosely fitted inside the shaft portion of the right planetary transmission mechanism's planet carrier. One end of the right output inner shaft is connected to the right wheel, and the other end is connected to the differential assembly.

[0009] The left and right motor rotors are supported on the electric vehicle by bearings at both ends, and the left and right motor stators are fixed to the electric vehicle.

[0010] The two ends of the planetary gears of the left planetary transmission mechanism are supported on the planet carrier of the left planetary transmission mechanism by the left support bearing and the right support bearing of the left planetary transmission mechanism; the two ends of the planetary gears of the right planetary transmission mechanism are supported on the planet carrier of the right planetary transmission mechanism by the left support bearing and the right support bearing of the right planetary transmission mechanism.

[0011] The output shafts at both ends of the differential assembly are supported on the electric vehicle via the left and right support bearings of the differential assembly, respectively.

[0012] The left and right constant mesh gears are supported on a support shaft by needle roller bearings. The support shaft is connected between the rotating shafts of the planetary gears of the left planetary transmission mechanism and the rotating shafts of the planetary gears of the right planetary transmission mechanism.

[0013] The right output inner shaft / left output inner shaft are equipped with an output disconnection mechanism.

[0014] A working method for a coaxial dual-motor drive axle assembly.

[0015] When the vehicle is in distributed drive operation mode, the clutches of the left planetary transmission ring gear and the right planetary transmission ring gear are engaged and braked, and the left motor assembly and the right motor assembly are working. At this time, the left motor rotor and the right motor rotor rotate, and the left synchronizer and the right synchronizer engage the left planetary transmission planet carrier and the right planetary transmission planet carrier respectively. Power is transmitted from the left motor rotor and the right motor rotor to the left planetary transmission planet gear and the right planetary transmission planet gear respectively, and then transmitted to the left planetary transmission planet carrier and the right planetary transmission planet carrier through the left synchronizer and the right synchronizer respectively, and then transmitted to the left wheel and the right wheel respectively.

[0016] When the vehicle is in single-motor drive mode, the clutches of the left planetary transmission ring gear / right planetary transmission ring gear are engaged and braked, the left motor assembly / right motor assembly works, the left motor rotor / right motor rotor rotates, and the left synchronizer / right synchronizer engages the left constant mesh gear / right constant mesh gear; power is transmitted from the left motor rotor / right motor rotor to the left planetary transmission ring gear / right planetary transmission ring gear, and then from the left planetary transmission ring gear / right planetary transmission ring gear to the left constant mesh gear / right constant mesh gear via the left synchronizer / right synchronizer, and then from the left constant mesh gear / right constant mesh gear to the main reduction gear, and finally to the left wheel and right wheel via the differential pack assembly with differential lock;

[0017] When the vehicle is in dual-motor drive mode, the clutches of the left and right planetary transmission gear rings are disengaged, and the left and right motor assemblies operate. The left synchronizer engages the left constant mesh gear, and the right synchronizer engages the right constant mesh gear. At this time, the left and right motor assemblies are working, and the left and right motor rotors rotate, driving the planetary gears of the left and right planetary transmission mechanisms to rotate. Power is transmitted through the left synchronizer to the left constant mesh gear, and through the right synchronizer to the right constant mesh gear. Then, the left and right constant mesh gears transmit the power to the main reduction gear, and finally through the differential lock assembly to the left and right wheels. When the left and right wheels of the vehicle slip, the differential lock assembly will lock, thus ensuring the vehicle's passability. When the vehicle needs to cut off power during the coasting phase, the output disconnection mechanism built into the right / left output inner shaft will disconnect, cutting off the power and preventing it from being transmitted to the wheels.

[0018] By employing the above technical solution, this invention possesses features such as independent wheel vector control, real-time switching of multiple power sources, prevention of wheel slippage, power disengagement, and coaxial design. It has the following beneficial effects:

[0019] This invention employs a coaxial, integrated design for both input and output, resulting in high integration and a compact size, thus maximizing vehicle space utilization. Distributed motor drive allows for real-time torque vector adjustment for each wheel based on differences in traction, improving the vehicle's passability. The single-motor or dual-motor drive modes offer greater flexibility in energy management strategy selection, contributing to energy conservation. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the structure of the present invention. Detailed Implementation

[0021] A coaxial dual-motor drive axle assembly includes a left wheel 1, a left motor assembly 2, a left planetary transmission mechanism assembly 3, a left synchronizer 4, a left constant mesh gear 5, a needle roller bearing 6, a right constant mesh gear 7, a right synchronizer 8, a right planetary transmission mechanism assembly 9, a right motor assembly 10, a right wheel 11, a differential assembly 12, a left output inner shaft 13, and a right output inner shaft 14.

[0022] The left motor assembly 2 includes a left motor rotor 2-3 and a left motor stator 2-4, and the right motor assembly 10 includes a right motor rotor 10-3 and a right motor stator 10-4. The opposing ends of the left motor rotor 2-3 and the right motor rotor 10-3 are connected to a sun gear, and the left motor rotor 2-3 and the right motor rotor 10-3 have axial inner holes.

[0023] The left planetary transmission assembly 3 includes a left planetary transmission planetary gear 3-3, a left planetary transmission planet carrier 3-4, and a left planetary transmission ring gear 3-5. The left planetary transmission ring gear 3-5 has a clutch for self-braking. The left planetary transmission planetary gear 3-3 is mounted on the left planetary transmission planet carrier 3-4. The left planetary transmission planet carrier 3-4 has a shaft portion loosely fitted inside the left motor rotor 2-3. The shaft portion of the left planetary transmission planet carrier 3-4 is connected to the left wheel 1. The left planetary transmission planetary gear 3-3 meshes with the sun gear on the left motor rotor 2-3 and the left planetary transmission ring gear 3-5, respectively. The right planetary transmission assembly 9 includes a right planetary transmission planetary gear 9-3, a right planetary transmission planet carrier 9-4, and a right planetary transmission ring gear 9-5. Ring 9-5 has a clutch for braking itself. The planetary gear 9-3 of the right planetary transmission mechanism is mounted on the planetary carrier 9-4 of the right planetary transmission mechanism. The planetary carrier 9-4 of the right planetary transmission mechanism has a shaft that is loosely fitted inside the right motor rotor 10-3. The shaft of the planetary carrier 9-4 of the right planetary transmission mechanism is connected to the right wheel 11. The planetary gear 9-3 of the right planetary transmission mechanism meshes with the sun gear on the right motor rotor 10-3 and the ring gear 9-5 of the right planetary transmission mechanism. One end of the shaft of the planetary gear 3-3 of the left planetary transmission mechanism passes through the planetary carrier 3-4 of the left planetary transmission mechanism and is connected to the left synchronizer 4. One end of the shaft of the planetary gear 9-3 of the right planetary transmission mechanism passes through the planetary carrier 9-4 of the right planetary transmission mechanism and is connected to the right synchronizer 8. The opposite ends of the planetary carrier 3-4 of the left planetary transmission mechanism and the planetary carrier 9-4 of the right planetary transmission mechanism are provided with a synchronous engagement surface.

[0024] The differential assembly 12 is equipped with a differential lock. The differential assembly 12 includes a main reduction gear 12-3. The left constant mesh gear 5 and the right constant mesh gear 7 both mesh with the main reduction gear 12-3. The opposite ends of the left constant mesh gear 5 and the right constant mesh gear 7 are provided with synchronous engagement surfaces. The left synchronizer 4 is located between the synchronous engagement surface of the planetary carrier 3-4 of the left planetary transmission mechanism and the synchronous engagement surface of the left constant mesh gear 5. The right synchronizer 8 is located between the synchronous engagement surface of the planetary carrier 9-4 of the right planetary transmission mechanism and the synchronous engagement surface of the right constant mesh gear 7. The left output inner shaft 13 is loosely fitted inside the shaft portion of the planetary carrier 3-4 of the left planetary transmission mechanism. One end of the left output inner shaft 13 is connected to the left wheel 1, and the other end is connected to the differential assembly 12. The right output inner shaft 14 is loosely fitted inside the shaft portion of the planetary carrier 9-4 of the right planetary transmission mechanism. One end of the right output inner shaft 14 is connected to the right wheel 11, and the other end is connected to the differential assembly 12.

[0025] The left motor rotor 2-3 and the right motor rotor 10-3 are supported on the electric vehicle by bearings at both ends, and the left motor stator 2-4 and the right motor stator 10-4 are fixed to the electric vehicle.

[0026] The two ends of the planetary gear 3-3 of the left planetary transmission mechanism are supported on the planet carrier 3-4 of the left planetary transmission mechanism by the left support bearing 3-1 and the right support bearing 3-2 of the left planetary transmission mechanism; the two ends of the planetary gear 9-3 of the right planetary transmission mechanism are supported on the planet carrier 9-4 of the right planetary transmission mechanism by the left support bearing 9-1 and the right support bearing 9-2 of the right planetary transmission mechanism.

[0027] The output shafts at both ends of the differential assembly 12 are supported on the electric vehicle via the left differential support bearing 12-1 and the right differential support bearing 12-2, respectively.

[0028] The left constant mesh gear 5 and the right constant mesh gear 7 are supported on the support shaft by the needle roller bearing 6. The support shaft is connected between the rotating shaft of the planetary gear 3-3 of the left planetary transmission mechanism and the rotating shaft of the planetary gear 9-3 of the right planetary transmission mechanism.

[0029] The right output inner shaft 14 and the left output inner shaft are equipped with an output disconnection mechanism 14-1.

[0030] A working method for a coaxial dual-motor drive axle assembly.

[0031] When the vehicle is in distributed drive operation mode, the clutches of the left planetary transmission mechanism ring gear 3-5 and the right planetary transmission mechanism ring gear 9-5 are engaged and braked, and the left motor assembly 2 and the right motor assembly 10 are working. At this time, the left motor rotor 2-3 and the right motor rotor 10-3 rotate, and the left synchronizer 4 and the right synchronizer 8 are engaged with the left planetary transmission mechanism planet carrier 3-4 and the right planetary transmission mechanism planet carrier 9-4 respectively. Power is transmitted from the left motor rotor 2-3 and the right motor rotor 10-3 to the left planetary transmission mechanism planet gear 3-3 and the right planetary transmission mechanism planet gear 9-3 respectively, and then through the left synchronizer 4 and the right synchronizer 8 to the left planetary transmission mechanism planet carrier 3-4 and the right planetary transmission mechanism planet carrier 9-4, and then to the left wheel 1 and the right wheel 11 respectively.

[0032] When the vehicle is in single-motor drive mode, the clutches of the left planetary transmission gear ring 3-5 and the right planetary transmission gear ring are engaged and braked, the left motor assembly 2 and the right motor assembly are working, the left motor rotor 2-3 and the right motor rotor rotate, and the left synchronizer 4 and the right synchronizer engage the left constant mesh gear 5 and the right constant mesh gear. Power is transmitted from the left motor rotor 2-3 and the right motor rotor to the left planetary transmission gear 3-3 and the right planetary transmission gear, and then from the left planetary transmission gear 3-3 and the right planetary transmission gear to the left constant mesh gear 5 and the right constant mesh gear via the left synchronizer 4 and the right synchronizer. Then, it is transmitted from the left constant mesh gear 5 and the right constant mesh gear to the main reduction gear 12-3, and finally to the left wheel 1 and the right wheel 11 via the differential package assembly 12 with differential lock.

[0033] When the vehicle is in dual-motor drive mode, the clutches of the left planetary transmission gear ring 3-5 and the right planetary transmission gear ring 9-5 are disengaged, and the left motor assembly 2 and the right motor assembly 10 are activated. The left synchronizer 4 engages the left constant mesh gear 5, and the right synchronizer 8 engages the right constant mesh gear 7. At this time, the left motor assembly 2 and the right motor assembly 10 are activated, and the left motor rotor 2-3 and the right motor rotor 10-3 rotate, driving the planetary gears 3-3 and 9-3 of the left planetary transmission mechanism to rotate. The power is transmitted to the left constant mesh gear via the left synchronizer 4. 5. The right synchronizer 8 transmits power to the right constant mesh gear 7, and then the left constant mesh gear 5 and the right constant mesh gear 7 transmit power to the main reduction gear 12-3. Finally, the power is transmitted to the left wheel 1 and the right wheel 11 via the differential lock assembly 12. When the left wheel 1 and the right wheel 11 of the vehicle slip, the differential lock assembly 12 will lock, thereby ensuring the passability of the vehicle. When the vehicle needs to cut off power during the coasting phase, the output disconnection mechanism 14-1 built on the right output inner shaft 14 / left output inner shaft will disconnect the power and it will not be transmitted to the wheels.

[0034] In this embodiment, refer to Figure 1 A coaxial dual-motor drive axle assembly structure comprises a left wheel 1, a left motor assembly 2, a left planetary transmission mechanism assembly 3, a left synchronizer 4, a left constant mesh gear 5, a needle roller bearing 6, a right constant mesh gear 7, a right synchronizer 8, a right planetary transmission mechanism assembly 9, a right motor assembly 10, a right wheel 11, a differential pack assembly with a differential lock 12, a left output inner shaft 13, and a right output inner shaft 14.

[0035] The left motor assembly 2 includes a left motor left support bearing 2-1, a left motor right support bearing 2-2, a left motor rotor 2-3 with a sun gear, and a left motor stator 2-4. The left motor assembly 2 is supported by the left motor left support bearing 2-1 and the left motor right support bearing 2-2.

[0036] The left planetary transmission mechanism assembly 3 includes a left planetary transmission mechanism left support bearing 3-1, a left planetary transmission mechanism right support bearing 3-2, a left planetary transmission mechanism planetary gear 3-3, a left planetary transmission mechanism planet carrier 3-4, and a left planetary transmission mechanism gear ring 3-5 with a clutch. The left planetary transmission mechanism planetary gear 3-3 is supported by the left planetary transmission mechanism left support bearing 3-1 and the left planetary transmission mechanism right support bearing 3-2.

[0037] The right planetary transmission mechanism assembly 9 includes a right planetary transmission mechanism left support bearing 9-1, a right planetary transmission mechanism right support bearing 9-2, a right planetary transmission mechanism planetary gear 9-3, a right planetary transmission mechanism planet carrier 9-4, and a right planetary transmission mechanism gear ring 9-5 with a clutch. The right planetary transmission mechanism planetary gear 9-3 is supported by the right planetary transmission mechanism left support bearing 9-1 and the right planetary transmission mechanism right support bearing 9-2.

[0038] The right motor assembly 10 includes a right motor left support bearing 10-1, a right motor right support bearing 10-2, a right motor rotor 10-3 with a sun gear, and a right motor stator 10-4. The right motor assembly 10 is supported by the right motor left support bearing 10-1 and the right motor right support bearing 10-2.

[0039] The differential package assembly 12 with differential lock includes a left differential support bearing 12-1, a right differential support bearing 12-2, a main reduction gear 12-3, and the differential package assembly 12, which is supported by the left differential support bearing 12-1 and the right differential support bearing 12-2.

[0040] The right output inner shaft 14 has a built-in output disconnection mechanism 14-1.

[0041] In this embodiment, when the vehicle is in a distributed drive operating state, the left motor assembly 2 and the right motor assembly 10 are operational. At this time, the left motor rotor 2-3 and the right motor rotor 10-3 with sun gears rotate, and the left planetary transmission gear ring 3-5 with clutch and the right planetary transmission gear ring 9-5 with clutch are in a closed state. The left synchronizer 4 and the right synchronizer 8 are engaged with the left planetary transmission gear planet carrier 3-4 and the right planetary transmission gear planet carrier 9-4, respectively. Power is transmitted from the left motor rotor 2-3 and the right motor rotor 10-3 with sun gears to the left planetary transmission gear planets 3-3 and 9-3, respectively, and then through the left synchronizer 4 and the right synchronizer 8 to the left planetary transmission gear planet carrier 3-4 and the right planetary transmission gear planet carrier 9-4. This power is then transmitted to the left wheel 1 and the right wheel 11, respectively.

[0042] In this embodiment, when the vehicle is in single-motor drive mode, for example, when the left motor assembly 2 is working, the left motor rotor 2-3 with the sun gear rotates, the left planetary transmission mechanism gear ring 3-5 with clutch is in a closed state, and the left synchronizer 4 is engaged with the left constant mesh gear 5. At this time, the power is transmitted from the left motor rotor 2-3 with the sun gear to the planet gear 3-3 of the left planetary transmission mechanism, and then from the planet gear 3-3 of the left planetary transmission mechanism to the left constant mesh gear 5 via the left synchronizer 4, and then from the left constant mesh gear 5 to the main reduction gear 12-3, and finally to the left wheel 1 and the right wheel 11 via the differential package assembly 12 with differential lock.

[0043] Similarly, when the right motor assembly 10 is working, the power is transmitted through a series of transmissions and finally transmitted to the left wheel 1 and the right wheel 11 via the differential lock assembly 12.

[0044] In this embodiment, when the vehicle is in dual-motor drive mode, the left motor assembly 2 and the right motor assembly 10 are working, the left planetary transmission gear ring 3-5 with clutch is disengaged, and the right planetary transmission gear ring 9-5 with clutch is disengaged. The left synchronizer 4 engages the left constant mesh gear 5, and the right synchronizer 8 engages the right constant mesh gear 7. At this time, the left motor assembly 2 and the right motor assembly 10 are working, and the left motor rotor 2-3 with sun gear and the right motor rotor 10-3 with sun gear rotate, driving the planetary gears 3-3 and 9-3 of the left and right planetary transmission mechanisms to rotate. The power is transmitted through the left synchronizer 4 to the left constant mesh gear 5 and through the right synchronizer 8 to the right constant mesh gear 7. Then, the left constant mesh gear 5 and the right constant mesh gear 7 transmit the power to the main reduction gear 12-3, and finally through the differential lock assembly 12 to the left wheel 1 and the right wheel 11. When the left wheel 1 and right wheel 11 of the vehicle slip, the differential package assembly 12 with differential lock will lock, thus ensuring the vehicle's passability. When the vehicle needs to cut off the power to the axle during the slipping phase, the output disconnect mechanism 14-1 on the right output inner axle 14 will disconnect, cutting off the power and preventing it from being transmitted to the wheels.

[0045] In summary, this invention features distributed drive, single-motor drive, and dual-motor simultaneous drive modes. In distributed drive mode, the differential lock-equipped differential does not engage. When entering single-motor or dual-motor simultaneous drive modes, the differential lock-equipped differential engages. When the wheels begin to slip on surfaces with low traction, the differential lock-equipped differential automatically locks to ensure vehicle traction. When the vehicle is coasting at high speed, the power can be cut off in real time as needed, thus better balancing the vehicle's economy and power performance. The structural features of this invention patent include: distributed drive, single-motor drive, dual-motor drive, coaxial design, planetary transmission mechanism, differential lock locking, and power cut-off.

[0046] This invention patent adopts a coaxial design, realizing the concept of miniaturization. Furthermore, a differential lock is designed into the dual-motor drive axle assembly, improving the vehicle's passability and enabling all-terrain operation. It also considers the vehicle's energy strategy, incorporating a disconnection mechanism that intervenes and disengages in real time according to the vehicle's energy strategy.

[0047] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made to it in form and detail without departing from the scope defined by the claims of the present invention.

Claims

1. A coaxial dual-motor drive axle assembly, characterized in that: Includes the left wheel, left motor assembly, left planetary transmission assembly, left synchronizer, left constant mesh gear, needle roller bearing, right constant mesh gear, right synchronizer, right planetary transmission assembly, right motor assembly, right wheel, differential assembly, left output inner shaft, and right output inner shaft. The left motor assembly includes a left motor rotor and a left motor stator, and the right motor assembly includes a right motor rotor and a right motor stator. The opposite ends of the left motor rotor and the right motor rotor are connected to a sun gear, and the left motor rotor and the right motor rotor have axial inner holes. The left planetary transmission assembly includes left planetary gears, a left planetary carrier, and a left planetary ring gear. The left planetary ring gear has a clutch for self-braking. The left planetary gears are mounted on the left planetary carrier, which has a shaft portion loosely fitted inside the left motor rotor. The shaft portion of the left planetary carrier is connected to a left wheel. The left planetary gears mesh with the sun gear and the left planetary ring gear on the left motor rotor, respectively. The right planetary transmission assembly includes right planetary gears, a right planetary carrier, and a right planetary ring gear. The ring gear has a clutch for braking itself. The planetary gears of the right planetary transmission mechanism are mounted on the planetary carrier of the right planetary transmission mechanism. The planetary carrier of the right planetary transmission mechanism has a shaft that is loosely fitted inside the rotor of the right motor. The shaft of the planetary carrier of the right planetary transmission mechanism is connected to the right wheel. The planetary gears of the right planetary transmission mechanism mesh with the sun gear and the ring gear of the right planetary transmission mechanism on the rotor of the right motor respectively. One end of the shaft of the planetary gear of the left planetary transmission mechanism passes through the planetary carrier of the left planetary transmission mechanism and is connected to the left synchronizer. One end of the shaft of the planetary gear of the right planetary transmission mechanism passes through the planetary carrier of the right planetary transmission mechanism and is connected to the right synchronizer. The opposite ends of the planetary carriers of the left and right planetary transmission mechanisms are provided with synchronous engagement surfaces. The differential assembly includes a differential lock and a main reduction gear. Both the left and right constant mesh gears mesh with the main reduction gear. The opposing ends of the left and right constant mesh gears have synchronous engagement surfaces. The left synchronizer is located between the synchronous engagement surfaces of the left planetary transmission mechanism's planet carrier and the left constant mesh gear. The right synchronizer is located between the synchronous engagement surfaces of the right planetary transmission mechanism's planet carrier and the right constant mesh gear. The left output inner shaft is loosely fitted inside the shaft portion of the left planetary transmission mechanism's planet carrier. One end of the left output inner shaft is connected to the left wheel, and the other end is connected to the differential assembly. The right output inner shaft is loosely fitted inside the shaft portion of the right planetary transmission mechanism's planet carrier. One end of the right output inner shaft is connected to the right wheel, and the other end is connected to the differential assembly.

2. The coaxial dual-motor drive axle assembly according to claim 1, characterized in that: The left and right motor rotors are supported on the electric vehicle by bearings at both ends, and the left and right motor stators are fixed to the electric vehicle.

3. The coaxial dual-motor drive axle assembly according to claim 1, characterized in that: The two ends of the planetary gears of the left planetary transmission mechanism are supported on the planet carrier of the left planetary transmission mechanism by the left support bearing and the right support bearing of the left planetary transmission mechanism; the two ends of the planetary gears of the right planetary transmission mechanism are supported on the planet carrier of the right planetary transmission mechanism by the left support bearing and the right support bearing of the right planetary transmission mechanism.

4. The coaxial dual-motor drive axle assembly according to claim 1, characterized in that: The output shafts at both ends of the differential assembly are supported on the electric vehicle via the left and right support bearings of the differential assembly, respectively.

5. The coaxial dual-motor drive axle assembly according to claim 1, characterized in that: The left and right constant mesh gears are supported on a support shaft by needle roller bearings. The support shaft is connected between the rotating shafts of the planetary gears of the left planetary transmission mechanism and the rotating shafts of the planetary gears of the right planetary transmission mechanism.

6. The coaxial dual-motor drive axle assembly according to claim 1, characterized in that: The right output inner shaft / left output inner shaft are equipped with an output disconnection mechanism.

7. A method for operating the coaxial dual-motor drive axle assembly as described in claim 1, characterized in that: When the vehicle is in distributed drive operation mode, the clutches of the left planetary transmission ring gear and the right planetary transmission ring gear are engaged and braked, and the left motor assembly and the right motor assembly are working. At this time, the left motor rotor and the right motor rotor rotate, and the left synchronizer and the right synchronizer engage the left planetary transmission planet carrier and the right planetary transmission planet carrier respectively. Power is transmitted from the left motor rotor and the right motor rotor to the left planetary transmission planet gear and the right planetary transmission planet gear respectively, and then transmitted to the left planetary transmission planet carrier and the right planetary transmission planet carrier through the left synchronizer and the right synchronizer respectively, and then transmitted to the left wheel and the right wheel respectively. When the vehicle is in single-motor drive mode, the clutches of the left planetary transmission ring gear / right planetary transmission ring gear are engaged and braked, the left motor assembly / right motor assembly works, the left motor rotor / right motor rotor rotates, and the left synchronizer / right synchronizer engages the left constant mesh gear / right constant mesh gear; power is transmitted from the left motor rotor / right motor rotor to the left planetary transmission ring gear / right planetary transmission ring gear, and then from the left planetary transmission ring gear / right planetary transmission ring gear to the left constant mesh gear / right constant mesh gear via the left synchronizer / right synchronizer, and then from the left constant mesh gear / right constant mesh gear to the main reduction gear, and finally to the left wheel and right wheel via the differential pack assembly with differential lock; When the vehicle is in dual-motor drive mode, the clutches of the left and right planetary transmission gear rings are disengaged, and the left and right motor assemblies operate. The left synchronizer engages the left constant mesh gear, and the right synchronizer engages the right constant mesh gear. At this time, the left and right motor assemblies are working, and the left and right motor rotors rotate, driving the planetary gears of the left and right planetary transmission mechanisms to rotate. Power is transmitted through the left synchronizer to the left constant mesh gear, and through the right synchronizer to the right constant mesh gear. Then, the left and right constant mesh gears transmit the power to the main reduction gear, and finally through the differential lock assembly to the left and right wheels. When the left and right wheels of the vehicle slip, the differential lock assembly will lock, thus ensuring the vehicle's passability. When the vehicle needs to cut off power during the coasting phase, the output disconnection mechanism built into the right / left output inner shaft will disconnect, cutting off the power and preventing it from being transmitted to the wheels.

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