An electric drive axle system and a method of operating the same

Abstract

The application provides an electric drive axle system and a working method thereof, and relates to the field of electric drive axle systems.The electric drive axle system comprises a differential, the differential comprises a shell, a side gear one and a side gear two are oppositely arranged in the shell, an output shaft of the side gear one is connected with a half shaft one through a clutch one, an output shaft of the side gear two is connected with a half shaft two through a clutch two, a driving gear is arranged on the shell, the electric drive axle system further comprises a motor one and a motor two, the motor one drives a third gear, the third gear can drive the driving gear to rotate, a ninth gear is driven by a motor shaft two, the ninth gear can drive the driving gear to rotate, the motor one further drives a gear shifting mechanism one, the gear shifting mechanism one can be engaged with a transmission gear set one on the half shaft one, the motor two further drives a gear shifting mechanism two, the gear shifting mechanism two can be engaged with a transmission gear set two on the half shaft two.The electric drive axle system can effectively improve the economy of the whole vehicle, and can solve the problem of tire wear under complex road conditions.

Description

Technical Field

[0001] This invention relates to the field of electric drive bridges, and more particularly to an electric drive bridge system and its operating method. Background Technology

[0002] A mechanical differential is a mechanism that allows the left and right (or front and rear) drive wheels to rotate at different speeds. The differential consists of planetary gears, a planetary gear carrier (differential housing), half-shaft gears, and other parts. The engine's power enters the differential through the drive shaft, directly driving the planetary gear carrier. The planetary gears then drive the left and right half-shafts, which in turn drive the left and right wheels respectively. When the car is moving straight, the left and right wheels and the planetary gear carrier rotate at the same speed, which is in a balanced state. However, when the car turns, this balance is disrupted, causing the inner wheel to rotate at a slower speed and the outer wheel to rotate at a faster speed. However, using a mechanical differential on an electric drive axle increases the number of mechanical differentials and gear transmissions, reduces the system's transmission path and efficiency, and cannot effectively balance the overall vehicle economy.

[0003] In the prior art, in order to avoid the influence of mechanical differentials being greater than transmission efficiency, a wheel-side direct drive method is used instead of a mechanical differential. That is, two motors directly drive the corresponding half shafts, and the speed of the two motors is controlled by electronic control, thereby achieving different speeds for the two half shafts, i.e., the wheels. This technical solution has the advantages of short power transmission path and high transmission efficiency.

[0004] However, with the above technical solutions, since there is no mechanical differential, the differential control of the left and right motors relies entirely on electronic control. It is necessary to identify the road excitation load spectrum. In poor road conditions such as uneven roads, curves and slopes, the time difference in response speed and the error in identifying the excitation load spectrum make it difficult for the tire speeds on both sides to meet the driving requirements. This results in tire wear and uneven tire wear in poor road conditions. At the same time, in order to meet the torque requirements, it is often necessary to match a motor with higher power and torque. On the one hand, this increases the cost, and on the other hand, the significant increase in unsprung mass greatly affects the handling and comfort of the vehicle. Summary of the Invention

[0005] To address the technical problem of tire wear and uneven wear on wheels caused by electric drive axles under complex working conditions in the prior art, this invention provides an electric drive axle system and its operating method, which can effectively improve the overall vehicle economy while also solving the tire wear and uneven wear problem under complex road conditions.

[0006] To solve the above-mentioned technical problems, in a first aspect, the present invention provides an electric drive axle system, including a differential. The differential includes a housing, inside which a first side gear and a second side gear are disposed opposite to each other. The output shaft of the first side gear is connected to a first half-shaft via a first clutch, and the output shaft of the second side gear is connected to a second half-shaft via a second clutch. A drive gear is disposed on the housing. The system also includes a first motor and a second motor. The first motor drives a third gear, which is capable of driving the drive gear to rotate. The second motor drives a ninth gear, which is capable of driving the drive gear to rotate. The first motor also drives a first shifting mechanism, which is capable of meshing with a first transmission gear set on the first half-shaft. The second motor also drives a second shifting mechanism, which is capable of meshing with a second transmission gear set on the second half-shaft. By coordinating the differential, motor one, motor two, clutch one, clutch two, shift mechanism one, and shift mechanism two, the driver can choose whether the differential drives half shaft one and half shaft two, or whether motor one and motor two drive half shaft one and half shaft two, depending on the working conditions and road conditions. This fully utilizes the advantages of wheel-side drive and mechanical differential drive, effectively improving the overall vehicle economy and solving the problem of tire wear under complex working conditions.

[0007] Furthermore, the first motor is connected to a first motor connecting shaft, on which the third gear is mounted. The first shifting mechanism is mounted on the first motor connecting shaft. The second motor is connected to a second motor connecting shaft, on which the ninth gear is mounted. The second shifting mechanism is mounted on the second motor connecting shaft. By arranging the first shifting mechanism, the third gear, the second shifting mechanism, and the ninth gear coaxially, the longitudinal space occupied is reduced, facilitating chassis layout.

[0008] Furthermore, the first shifting mechanism is located between the third gear and the first motor, and the second shifting mechanism is located between the ninth gear and the second motor. By placing the first and second shifting mechanisms in the middle, support for the shifting mechanism at both ends can be achieved, avoiding the formation of a cantilever beam support structure.

[0009] Furthermore, the third gear is located between the first shift mechanism and the first motor, and the ninth gear is located between the second shift mechanism and the second motor.

[0010] Furthermore, the first transmission gear set includes an eighth gear and a seventh gear coaxially arranged, the eighth gear and the seventh gear being keyed to the half-shaft; the first shifting mechanism includes a fifth gear, a shifting actuator, and a sixth gear, the fifth gear and the sixth gear being rotatably mounted on the first motor connecting shaft, the fifth gear meshing with the eighth gear, and the sixth gear meshing with the seventh gear; the second transmission gear set includes a first gear and a second gear coaxially arranged, the first gear and the second gear being keyed to the half-shaft; the second shifting mechanism includes an eleventh gear, a shifting actuator, and a tenth gear, the eleventh gear and the tenth gear being rotatably mounted on the first motor connecting shaft, the eleventh gear meshing with the first gear, and the tenth gear meshing with the second gear.

[0011] Furthermore, the first motor is connected to a first motor connecting shaft, on which the third gear is mounted. The third gear meshes with the twelfth gear, which in turn meshes with the drive gear. The twelfth gear is mounted on a third connecting shaft, and the first shifting mechanism is mounted on the third connecting shaft. The second motor is connected to a second motor connecting shaft, on which the ninth gear is mounted. The ninth gear meshes with the thirteenth gear, which in turn meshes with the drive gear. The thirteenth gear is mounted on a fourth connecting shaft, and the second shifting mechanism is mounted on the fourth connecting shaft. By adding the twelfth and thirteenth gears, the lateral space occupied can be reduced, facilitating chassis layout.

[0012] Furthermore, the first transmission gear set includes an eighth gear and a seventh gear coaxially arranged, the eighth gear and the seventh gear being keyed to the half-shaft. The first shifting mechanism includes a fifth gear, a shifting actuator, and a sixth gear, the fifth gear and the sixth gear being rotatably mounted on the third connecting shaft. The fifth gear meshes with the eighth gear, and the sixth gear meshes with the seventh gear. The second transmission gear set includes a first gear and a second gear coaxially arranged, the first gear and the second gear being keyed to the half-shaft. The second shifting mechanism includes an eleventh gear, a shifting actuator, and a tenth gear, the eleventh gear and the tenth gear being rotatably mounted on the fourth connecting shaft. The eleventh gear meshes with the first gear, and the tenth gear meshes with the second gear.

[0013] Furthermore, the transmission ratio between the sixth gear and the seventh gear is greater than the transmission ratio between the fifth gear and the eighth gear, and the transmission ratio between the eleventh gear and the first gear is greater than the transmission ratio between the tenth gear and the second gear.

[0014] Furthermore, the first motor and the second motor are symmetrical about the center of the differential, and the first shift mechanism and the second shift mechanism are also symmetrical about the center of the differential. This symmetrical arrangement facilitates the distribution of axle loads between the front and rear axles. The dual-motor structure enables motor miniaturization, which is more conducive to modularization and lightweighting. Simultaneously, the real-time power and torque distribution of the dual motors can improve the motor load rate under low power conditions, thereby improving the overall vehicle economy.

[0015] Secondly, the present invention also provides a method for operating an electric drive bridge, employing the aforementioned electric drive bridge system. When the vehicle is coasting unloaded, both clutches 1 and 2 are disengaged, and shift mechanisms 1 and 2 are in neutral. When the vehicle is under parking brake, both clutches 1 and 2 are engaged, and shift mechanisms 1 and 2 are in gear. When the vehicle is traveling at medium to high speeds on good road conditions, both clutches 1 and 2 are disengaged, and shift mechanisms 1 and 2 are in high gear. When the vehicle is starting fully loaded, climbing at low to medium speeds on good road conditions, both clutches 1 and 2 are disengaged, and shift mechanisms 1 and 2 are in low gear. When the vehicle is on poor road conditions, both clutches 1 and 2 are engaged, and shift mechanisms 1 and 2 are in neutral. These multiple operating modes cover all the vehicle's needs for coasting, towing, efficient and economical cruising, and handling complex conditions, achieving both economy and efficient transmission.

[0016] As can be seen from the above technical solutions, the present invention has the following advantages: This invention provides an electric drive axle system and its operating method. Through the coordination of a differential, motor one, motor two, clutch one, clutch two, shift mechanism one, and shift mechanism two, the driver can choose whether the differential drives half-shafts one and two, or whether motor one and motor two drive them, based on working conditions and road conditions. This fully utilizes the advantages of wheel-side drive and mechanical differential drive, effectively improving vehicle economy and solving the problem of tire wear under complex working conditions. By coaxially arranging shift mechanism one with the third gear, shift mechanism two, and the ninth gear, longitudinal space occupancy is reduced, facilitating chassis layout. The gear shift mechanism is positioned in the middle, allowing for support from both ends and avoiding the formation of a cantilever beam support structure. The addition of twelfth and thirteenth gears reduces lateral space requirements, facilitating chassis layout. Symmetrical arrangement promotes axle load distribution between the front and rear axles. The dual-motor structure enables motor miniaturization, further facilitating modularization and lightweighting. Real-time power and torque distribution between the dual motors improves motor load rate under low power conditions, thereby enhancing overall vehicle economy. Multiple operating modes cover all vehicle requirements for coasting, towing, efficient and economical cruising, and handling complex conditions, achieving both economy and efficient transmission. Attached Figure Description

[0017] To more clearly illustrate the technical solution of the present invention, the accompanying drawings used in the description will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a structural schematic diagram of a specific embodiment of the present invention.

[0019] Figure 2 This is a schematic diagram of the assembly structure of shift mechanism one, shift mechanism two, and differential in a specific embodiment of the present invention.

[0020] In the diagram: 1. Wheel assembly 2; 2. Half-shaft 2; 3. First gear; 4. Second gear; 5. Clutch 2; 7. Third gear; 8. Motor connecting shaft 1; 9. Drive gear; 10. Fifth gear; 11. Gear shifting mechanism 1; 12. Sixth gear; 13. Motor 1; 14. Wheel assembly 1; 15. Half-shaft 1; 16. Seventh gear; 17. Eighth gear; 18. Clutch 1; 20. Differential; 21. Ninth gear; 22. Motor connecting shaft 2; 23. Tenth gear; 24. Gear shifting mechanism 2; 25. Eleventh gear; 26. Motor 2; 27. Connecting shaft 3; 28. Thirteenth gear; 29. ​​Connecting shaft 4; 30. Twelfth gear. Detailed Implementation

[0021] To make the objectives, features, and advantages of this invention more apparent and understandable, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings of the specific embodiments. Obviously, the embodiments described below are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this patent, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this patent. Specific Implementation Method 1 like Figure 1As shown in the figure, this specific embodiment provides an electric drive axle system, including a differential 20, a first half-shaft 15, a second half-shaft 2, a first motor 13, and a second motor 26. A wheel assembly 14 is provided at one end of the first half-shaft 15, and a second wheel assembly 1 is provided at one end of the second half-shaft 2. The differential 20 includes a housing, inside which a first side gear and a second side gear are arranged opposite to each other. A gear set is also provided inside the housing, capable of meshing with the first and second side gears respectively. The output shaft of the first side gear is connected to the first half-shaft 15 via a first clutch 18, and the output shaft of the second side gear is connected to the second half-shaft via a second clutch 26. 5 is connected to half shaft 2. The housing is connected by a spline and has a drive gear 9. Motor 13 drives a third gear 7. The third gear 7 can drive the drive gear 9 to rotate and thus drive the differential 20 to work. Motor 26 drives a ninth gear 21. The ninth gear 21 can drive the drive gear 9 to rotate and thus drive the differential 20 to work. Motor 13 also drives a shift mechanism 1. The shift mechanism 1 can mesh with the transmission gear set 1 on half shaft 15. Motor 26 also drives a shift mechanism 2. The shift mechanism 2 can mesh with the transmission gear set 2 on half shaft 2. Through the coordination of differential 20, motor 13, motor 26, clutch 18, clutch 25, shift mechanism 1 and shift mechanism 2, the driver can choose whether to drive half shaft 15 and half shaft 2 by differential 20 or by motor 13 and motor 26, depending on the working conditions and road conditions. This fully utilizes the advantages of wheel-side drive and mechanical differential drive, effectively improves the overall vehicle economy, and solves the problem of tire wear under complex working conditions.

[0023] like Figure 1 As shown, in order to reduce the longitudinal space occupied and facilitate the chassis layout, motor 13 is connected to motor connecting shaft 8, and a third gear 7 is connected to motor connecting shaft 8 via a key. Shift mechanism 1 is set on motor connecting shaft 8. Motor 26 is connected to motor connecting shaft 22, and a ninth gear 21 is set on motor connecting shaft 22 via a key. Shift mechanism 2 is set on motor connecting shaft 22.

[0024] like Figure 1 As shown, the third gear 7 can be located between the first shift mechanism and the first motor 13, and the ninth gear 21 can be located between the second shift mechanism and the second motor 26. However, in order to avoid the corresponding shift mechanisms forming a cantilever beam support, in this specific embodiment, the first shift mechanism is located between the third gear 7 and the first motor 13, and the second shift mechanism is located between the ninth gear 21 and the second motor 26.

[0025] like Figure 1As shown, in this specific embodiment, the first transmission gear set includes an eighth gear 17 and a seventh gear 16 coaxially arranged. The eighth gear 17 and the seventh gear 16 are connected to the first half-shaft 15 via a flat key. The first shifting mechanism includes a fifth gear 10, a shifting actuator 11, and a sixth gear 12. The fifth gear 10 and the sixth gear 12 are rotatably mounted on the first motor connecting shaft 8 via bearings. The fifth gear 10 meshes with the eighth gear 17, and the sixth gear 12 meshes with the seventh gear 16. The second transmission gear set includes a first gear 3 and a second gear 4 coaxially arranged. The first gear 3 and the second gear 4 are connected to the second half-shaft 2 via a key. The second shifting mechanism includes an eleventh gear 25, a shifting actuator 24, and a tenth gear 23. The eleventh gear 25 and... The tenth gear 23 is rotatably mounted on the motor connecting shaft 8 via a bearing. The eleventh gear 25 meshes with the first gear 3, and the tenth gear 23 meshes with the second gear 4. The transmission ratio between the sixth gear 12 and the seventh gear 16 is greater than the transmission ratio between the fifth gear 10 and the eighth gear 17, and the transmission ratio between the eleventh gear 25 and the first gear 3 is greater than the transmission ratio between the tenth gear 23 and the second gear 4. That is, when the shifting actuator 11 meshes with the sixth gear 12, it is a low-speed, high-torque gear; when the shifting actuator 11 meshes with the fifth gear 10, it is a high-speed, low-torque gear; when the shifting actuator 24 meshes with the eleventh gear 25, it is a low-speed, high-torque gear; and when the shifting actuator 24 meshes with the tenth gear 23, it is a high-speed, low-torque gear.

[0026] like Figure 1 As shown in this specific embodiment, motor 13 and motor 26 are symmetrical about the differential 20, and shift mechanism 1 and shift mechanism 2 are symmetrical about the differential 20. The symmetrical arrangement is conducive to the distribution of axle load between the front and rear axles. The dual-motor structure enables motor miniaturization, which is more conducive to modularization and lightweighting. At the same time, the power and torque of the dual motors are distributed in real time, which can improve the motor load rate of the vehicle under low power, thereby improving the overall vehicle economy.

[0027] In this specific embodiment, the shift actuator 11 and the shift actuator 24 have the same structure, both including a transmission gear. The transmission gear is keyed to the corresponding motor connecting shaft. A sliding sleeve is axially movable on the outer circumference of the gear. The sliding sleeve can connect the corresponding shift gear to the gear to realize the access of power. Specific Implementation Method Two like Figure 2As shown, this specific embodiment provides an electric drive axle system, which is basically the same in structure as the electric drive axle system in specific embodiment one. The difference is that: motor one 13 is connected to motor connecting shaft one 8, and a third gear 7 is keyed on motor connecting shaft one 8. The third gear 7 meshes with the twelfth gear 30, and the twelfth gear 30 meshes with the drive gear 9. The twelfth gear 30 is keyed on connecting shaft three 27. Shifting mechanism one is set on connecting shaft three 27. Motor two 26 is connected to motor connecting shaft two 22, and a ninth gear 21 is keyed on motor connecting shaft two 22. The ninth gear 21 meshes with the thirteenth gear 28, and the thirteenth gear 28 meshes with the drive gear 9. The thirteenth gear 28 is keyed on connecting shaft four 29. Shifting mechanism two is set on connecting shaft four 29. By adding the twelfth gear 30 and the thirteenth gear 28, the lateral space occupied can be shortened, which is convenient for chassis layout.

[0029] like Figure 2 As shown, in this specific embodiment, the first transmission gear set includes an eighth gear 17 and a seventh gear 16 coaxially arranged. The eighth gear 17 and the seventh gear are keyed to a half-shaft 15. The first gear shifting mechanism includes a fifth gear 10, a shifting actuator 11, and a sixth gear 12. The fifth gear 10 and the sixth gear 12 are rotatably mounted on a connecting shaft 27. The fifth gear 10 meshes with the eighth gear 17, and the sixth gear 12 meshes with the seventh gear 16. The second transmission gear set includes a first gear 3 and a second gear 4 coaxially arranged. The first gear 3 and the second gear are keyed to a half-shaft 2. The second gear shifting mechanism includes an eleventh gear 25, a shifting actuator 24, and a tenth gear 23. The eleventh gear 25 and the tenth gear 23 are rotatably mounted on a connecting shaft 29 via bearings. The eleventh gear 25 meshes with the first gear 3, and the tenth gear 23 meshes with the second gear 4. Specific Implementation Method 3 This specific embodiment provides a method for operating an electric drive axle, employing the electric drive axle system of Specific Embodiment One. When the vehicle is coasting unloaded, both clutch 18 and clutch 25 are disengaged, and shift mechanisms 1 and 2 are in neutral. When the vehicle is under parking brake, both clutch 18 and clutch 25 are engaged, and shift mechanisms 1 and 2 are in gear. When the vehicle is traveling at medium to high speeds and the road conditions are good, wheel-side drive mode is used, i.e., both clutch 18 and clutch 25 are disengaged, shift mechanisms 1 and 2 are in high gear, and power is transmitted from motor 13 through shift mechanism 1 and eighth gear 17 to half-shaft 15, and also from motor 26 through shift mechanism 2 and second gear 4 to half-shaft 2. When the vehicle starts fully loaded, climbs hills at low to medium speeds, and on good road conditions, it uses wheel-side drive mode. Both clutches 18 and 25 are disengaged, and shift mechanisms 1 and 2 are in low gear. Power is transmitted from motor 13 through shift mechanism 1 and the seventh gear 16 to half-shaft 15, and also from motor 26 through shift mechanism 2 and the first gear 3 to half-shaft 2. When the road conditions are poor, it uses center differential mode, where both clutches 18 and 25 are engaged, and shift mechanisms 1 and 2 are in neutral. Power is transmitted from motor 13 through the third gear 7 to differential 20, and also from the ninth gear 21 to differential 20. These multiple operating modes cover all the vehicle's needs for coasting, towing, efficient and economical cruising, and handling complex conditions, achieving both economy and efficient transmission.

[0031] As can be seen from the above specific embodiments, the present invention has the following beneficial effects: 1. Through the coordination of differential 20, motor 13, motor 26, clutch 18, clutch 25, shift mechanism 1 and shift mechanism 2, the driver can choose whether to drive half shaft 15 and half shaft 2 by differential 20 or by motor 13 and motor 26 according to working conditions and road conditions. This fully utilizes the advantages of wheel-side drive and mechanical differential drive, effectively improves the economy of the vehicle, and solves the problem of tire wear under complex working conditions. 2. By arranging the first shift mechanism coaxially with the third gear 7, the second shift mechanism and the ninth gear 21, the longitudinal space occupied is reduced, which facilitates the chassis layout; 3. By placing shift mechanism one and shift mechanism two in the middle, the corresponding shift mechanisms can be supported at both ends, thus avoiding the formation of a cantilever beam support structure; 4. By adding the twelfth gear 30 and the thirteenth gear 28, the lateral space occupied can be reduced, which facilitates the chassis layout; 5. Symmetrical arrangement is conducive to the distribution of axle load between the front and rear axles. The dual-motor structure enables motor miniaturization, which is more conducive to modularization and lightweighting. At the same time, the power and torque of the dual motors are distributed in real time, which can improve the motor load rate of the vehicle under low power, thereby improving the overall vehicle economy. 6. By employing multiple operating modes to cover various working conditions of the vehicle, the vehicle achieves both economy and efficient transmission. These multiple operating modes cover all the vehicle's needs for coasting, towing, efficient and economical cruising, and handling complex working conditions, thus achieving both economy and efficient transmission.

[0032] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An electric drive axle system, comprising a differential (20), the differential (20) comprising a housing, wherein a first side gear and a second side gear are disposed opposite to each other inside the housing, characterized in that: The output shaft of the first side gear is connected to the first half shaft (15) via the first clutch (18), and the output shaft of the second side gear is connected to the second half shaft (2) via the second clutch (5). A drive gear (9) is provided on the housing. It also includes motor one (13) and motor two (26). Motor one (13) is driven by a third gear (7), which can drive the drive gear (9) to rotate. Motor two (26) is driven by a ninth gear (21), which can drive the drive gear (9) to rotate. Motor 1 (13) also drives a shift mechanism 1, which can mesh with a transmission gear set 1 on half shaft 1 (15). Motor 2 (26) also drives a shift mechanism 2, which can mesh with a transmission gear set 2 on half shaft 2 (2). Motor 1 (13) is connected to motor connecting shaft 1 (8), and a third gear (7) is provided on motor connecting shaft 1 (8). The third gear (7) meshes with the twelfth gear (30), and the twelfth gear (30) meshes with the drive gear (9). The twelfth gear (30) is provided on connecting shaft 3 (27), and shifting mechanism 1 is provided on connecting shaft 3 (27). Motor 2 (26) is connected to motor connecting shaft 2 (22), and a ninth gear (21) is provided on motor connecting shaft 2 (22). The ninth gear (21) meshes with the thirteenth gear (28), and the thirteenth gear (28) meshes with the drive gear (9). The thirteenth gear (28) is provided on connecting shaft 4 (29), and shifting mechanism 2 is provided on connecting shaft 4 (29).

2. The electric drive bridge system as described in claim 1, characterized in that: Motor 1 (13) is connected to motor connecting shaft 1 (8), and a third gear (7) is provided on motor connecting shaft 1 (8). Gear shifting mechanism 1 is provided on motor connecting shaft 1 (8). Motor 2 (26) is connected to motor connecting shaft 2 (22), and a ninth gear (21) is provided on motor connecting shaft 2 (22). Gear shifting mechanism 2 is provided on motor connecting shaft 2 (22).

3. The electric drive bridge system as described in claim 2, characterized in that: The first shift mechanism is located between the third gear (7) and the first motor (13), and the second shift mechanism is located between the ninth gear (21) and the second motor (26).

4. The electric drive bridge system as described in claim 2, characterized in that: The third gear (7) is located between the first shift mechanism and the first motor (13), and the ninth gear (21) is located between the second shift mechanism and the second motor (26).

5. The electric drive bridge system as described in claim 2, characterized in that: The transmission gear set one includes an eighth gear (17) and a seventh gear (16) arranged coaxially. The eighth gear (17) and the seventh gear are keyed to a half-shaft one (15). The gear shifting mechanism one includes a fifth gear (10), a shifting actuator one (11), and a sixth gear (12). The fifth gear (10) and the sixth gear (12) are rotatably mounted on a motor connecting shaft one (8). The fifth gear (10) meshes with the eighth gear (17), and the sixth gear (12) meshes with the seventh gear (16). The transmission gear set two includes a first gear (3) and a second gear (4) arranged coaxially. The first gear (3) and the second gear are keyed to the half shaft two (2). The gear shifting mechanism two includes an eleventh gear (25), a shifting execution mechanism two (24) and a tenth gear (23). The eleventh gear (25) and the tenth gear (23) are rotatably arranged on the motor connecting shaft one (8). The eleventh gear (25) meshes with the first gear (3) and the tenth gear (23) meshes with the second gear (4).

6. The electric drive bridge system as described in claim 1, characterized in that: The transmission gear set one includes an eighth gear (17) and a seventh gear (16) arranged coaxially. The eighth gear (17) and the seventh gear (16) are keyed to a half-shaft one (15). The shifting mechanism one includes a fifth gear (10), a shifting actuator one (11), and a sixth gear (12). The fifth gear (10) and the sixth gear (12) are rotatably mounted on a connecting shaft three (27). The fifth gear (10) meshes with the eighth gear (17), and the sixth gear (12) meshes with the seventh gear (16). The transmission gear set two includes a first gear (3) and a second gear (4) arranged coaxially. The first gear (3) and the second gear (4) are keyed to the half shaft two (2). The gear shifting mechanism two includes an eleventh gear (25), a shifting execution mechanism two (24) and a tenth gear (23). The eleventh gear (25) and the tenth gear (23) are rotatably arranged on the connecting shaft four (29). The eleventh gear (25) meshes with the first gear (3) and the tenth gear (23) meshes with the second gear (4).

7. The electric drive bridge system as described in claim 4 or 6, characterized in that: The transmission ratio of the sixth gear (12) to the seventh gear (16) is greater than that of the fifth gear (10) to the eighth gear (17), and the transmission ratio of the eleventh gear (25) to the first gear (3) is greater than that of the tenth gear (23) to the second gear (4).

8. The electric drive bridge system as described in claim 7, characterized in that: Motor 1 (13) and Motor 2 (26) are symmetrical about the differential (20), and shift mechanism 1 and shift mechanism 2 are symmetrical about the differential (20).

9. A method for operating an electric drive bridge, characterized in that: Using the electric drive axle system as described in claim 8, when the vehicle is coasting unloaded, both clutches 1 and 2 are disengaged, and shift mechanisms 1 and 2 are in neutral. When the vehicle is under parking brake, both clutches 1 and 2 are engaged, and shift mechanisms 1 and 2 are in gear. When the vehicle is traveling at medium to high speeds and the road conditions are good, both clutches 1 and 2 are disengaged, and shift mechanisms 1 and 2 are in high gear. When the vehicle is starting fully loaded, climbing at medium to low speeds and the road conditions are good, both clutches 1 and 2 are disengaged, and shift mechanisms 1 and 2 are in low gear. When the road conditions are poor, both clutches 1 and 2 are engaged, and shift mechanisms 1 and 2 are in neutral.

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