Electric drive axle and electric truck

Abstract

The present invention relates to an electric drive axle and an electric truck. The electric drive axle is provided with a main drive electric motor, an auxiliary drive electric motor, a speed reducer assembly and a differential assembly, wherein the speed reducer assembly is provided with a main drive first speed reduction stage, an auxiliary drive first speed reduction stage, a first-gear transmission mechanism, a second-gear transmission mechanism and a gear shifting mechanism, wherein the gear shifting mechanism enables switching between a first gear, a second gear and a neutral gear; the main drive electric motor transmits power to the differential assembly via the main drive first speed reduction stage by means of the first-gear transmission mechanism or the second-gear transmission mechanism; the speed reducer assembly is further provided with an auxiliary drive power disengagement device; and the auxiliary drive electric motor can transmit power to the first-gear transmission mechanism via the auxiliary drive first speed reduction stage by means of coupling of the auxiliary drive power disengagement device, and avoids passive idling by means of disconnection of the auxiliary drive power disengagement device. The electric truck provided by the present invention has the electric drive axle.

Description

E-axles and electric trucks

[0001] This application claims priority to Chinese Patent Application No. 202410050737.8 filed on January 15, 2024, and the contents of the above-mentioned Chinese patent application disclosure are hereby incorporated by reference in their entirety as a part of this application. Technical Field

[0002] The present invention relates to an electric drive axle and an electric truck. Background Art

[0003] The current market for electric axles in electric trucks, such as those used in medium- and heavy-duty trucks, generally adopts two main drive modes: single-motor drive or dual-motor drive. Single-motor drive significantly reduces the transport efficiency of heavy-duty electric trucks due to the limited power of the single motor at high speeds, resulting in poor acceleration and gradeability. Dual-motor drive, however, significantly reduces the efficiency of heavy-duty electric trucks when the vehicle is lightly loaded, as the dual motors cannot operate in their economic zone. This increases power consumption, poor vehicle economy, reduced range, and increased operating costs. Therefore, both single-motor and dual-motor drive axles are not conducive to market adoption.

[0004] Furthermore, in electric axles with differentials, the space available for the speed reducer and motor is even more limited due to the large space occupied by the differential, necessitating a more space-efficient speed reducer. Numerous electric axle designs for passenger cars are known in this regard, but they differ significantly from those for electric trucks in many respects, such as the balancing suspension and leaf springs on the chassis of electric trucks. Therefore, electric axles for passenger cars are generally not directly transferable to electric trucks.

[0005] Many types of speed reducers are known for electric axles in electric trucks, but many are merely designed in principle, often without considering the size and efficiency of the gears in the actual reduction stage, making them difficult to implement.

[0006] In addition, in an electric drive axle with a differential, the design of the electric drive axle also needs to consider the design of the transmission stage, among which the transmission stage from the motor to the differential (such as the design of spur gear transmission and planetary gear transmission) and the transmission stage from the differential to the wheel (such as the design of planetary gear transmission) require an overall design, and the design of the transmission stage also needs to be associated with the design of the motor, so that the motor can work in the high-efficiency zone as much as possible while ensuring high transmission efficiency.

[0007] Furthermore, the weight of the electric drive axle is also a key consideration, so the number of parts should be minimized while ensuring power and energy savings. Currently, there is no ideal solution for dual-motor electric drive axles that balances power, economy, and space utilization. Summary of the Invention

[0008] Based on the above-mentioned prior art, the technical problem to be solved by the present invention is to overcome the defects of the prior art to a large extent and provide an electric drive axle with high practical use value.

[0009] According to the present invention, the electric drive axle is used for an electric truck. The electric drive axle has a main drive motor, an auxiliary drive motor, a reducer assembly and a differential assembly, wherein the reducer assembly has a main drive first-stage reduction stage, an auxiliary drive first-stage reduction stage, a first-gear transmission mechanism, a second-gear transmission mechanism and a shift mechanism, wherein the shift mechanism realizes switching between first gear, second gear and neutral gear, wherein the main drive motor transmits power to the differential assembly via the main drive first-stage reduction stage through the first-gear transmission mechanism or the second-gear transmission mechanism, wherein the reducer assembly also has an auxiliary drive force disengaging device, and the auxiliary drive motor can transmit power to the first-gear transmission mechanism via the auxiliary drive first-stage reduction stage through the coupling of the auxiliary drive force disengaging device, and passive idling is avoided by disconnecting the auxiliary drive force disengaging device.

[0010] Here, the transmission design of the main drive motor ensures that the motor operates in the economic zone or high-efficiency zone under low-speed conditions, while achieving good climbing performance. The transmission design of the auxiliary drive motor meets the needs of the vehicle for acceleration and climbing under high-speed conditions. The use of an auxiliary drive force disengagement device can achieve the disengagement of the auxiliary drive motor under light load, achieve the need for power saving and avoid energy loss caused by passive idling of the motor. In addition, with the help of the coupling of the auxiliary drive force disengagement device, the vehicle can also operate only with the auxiliary drive motor. In addition, the design of the reducer assembly realizes multiple drive modes. In the scope of the present invention, the high-efficiency zone of the motor refers to the motor efficiency in the range of 90% to 97%. In the overall solution, the present invention has achieved an ideal solution that takes into account power, economy and space utilization, and will further highlight the beneficial technical effects in the preferred embodiment.

[0011] In a preferred embodiment of the present invention, the auxiliary drive motor is capable of transmitting power only to the first-gear transmission mechanism via the auxiliary drive primary reduction stage and through coupling with the auxiliary drive force disconnecting device. This means that the auxiliary drive motor does not directly transmit power to the second-gear transmission mechanism via the auxiliary drive primary reduction stage. Thus, the auxiliary drive force disconnecting device can completely disconnect the power of the auxiliary drive motor.

[0012] In a preferred embodiment of the present invention, the main drive first reduction stage comprises a first gear and a second gear meshing with each other, the first gear being connected to the main drive motor and the second gear being fixed on the first shaft, wherein the auxiliary drive first reduction stage comprises a third gear and a fourth gear meshing with each other, the third gear being connected to the auxiliary drive motor and the fourth gear being rotatably supported on the second shaft, furthermore, the first gear transmission mechanism comprises a first gear driving gear and a first gear driven gear, and the second gear transmission mechanism comprises a second gear driving gear and a second gear driven gear, wherein the first gear driving gear and the second gear driving gear are fixed on the first shaft and the first gear driven gear and the second gear driven gear are rotatably supported on the output shaft of the transmission assembly, furthermore, the shifting mechanism comprises an output shaft hub, a first gear driven gear hub, a second gear driven gear hub and a first gear sleeve, wherein the first gear sleeve can be located only on the output shaft hub, or can connect the first gear driven gear hub to the output shaft hub, and can connect the second gear driven gear hub to the output shaft hub. Through the above design, power transmission of the main drive motor is achieved, ensuring the power performance of the electric truck under low-speed conditions.

[0013] In a preferred embodiment of the present invention, the auxiliary driving force disengagement device includes a fourth gear hub, a second shaft hub, a second shaft, a second gear sleeve, and a fifth gear, wherein the second shaft hub is fixed to the second shaft, and the second gear sleeve is capable of connecting or disconnecting the fourth gear hub with the second shaft hub, wherein the fifth gear is fixed to the second shaft and meshes with the first gear driven gear. Here, the fourth gear does not mesh with the second gear driven gear. By setting the auxiliary driving force disengagement device according to the present invention, the auxiliary drive motor is disengaged when the load is light, thereby achieving the need for power saving; in addition, auxiliary power is provided when the load is heavy, and the power requirements under high-speed conditions and the low-speed climbing ability can be met.

[0014] In a preferred embodiment of the present invention, the output shaft is directly connected to the differential assembly. Within the scope of this invention, "direct connection" refers to the absence of an intermediate reduction stage, specifically the absence of a planetary gear reducer between the output shaft and the differential assembly. As a result, the main drive motor and the auxiliary drive motor can transmit power to the differential assembly via only two reduction stages, significantly improving transmission efficiency. Furthermore, this design saves space and improves the space utilization of the reducer assembly.

[0015] In a preferred embodiment of the present invention, the differential assembly is connected to the left and right half-axles of the electric truck, with the right half-axle passing through a hollow output shaft. Each of the left and right half-axles is directly connected to its corresponding wheel. In other words, no reduction stage is provided between the left and right half-axles and the wheels. This integrated design eliminates the need for wheel-mounted reducers, reducing manufacturing and assembly costs.

[0016] In a preferred embodiment of the present invention, the second gear is axially arranged between the first gear driving gear and the second gear driving gear. Furthermore, the fourth gear is axially arranged between the first gear driven gear and the second gear driven gear. Furthermore, the auxiliary drive force disengagement device is arranged between the shift mechanism and the auxiliary drive motor, with respect to the radial direction of the axle. This design achieves a more compact structure. In a preferred embodiment of the present invention, the main drive motor is arranged at the front of the electric drive axle, and the auxiliary drive motor is arranged at the rear of the electric drive axle, with respect to the direction of travel. This design makes the overall profile easier to adapt to other structures.

[0017] In a preferred embodiment of the present invention, the main drive motor, auxiliary drive motor, speed reducer assembly, and differential assembly are arranged in a common housing. This makes the electric drive axle design more compact and is particularly beneficial for the design of the lubrication system, thereby lubricating the components within the entire housing.

[0018] In a preferred embodiment of the present invention, the rated torque of the main drive motor is greater than 1000 Nm, and the rated torque of the auxiliary drive motor does not exceed the rated torque of the main drive motor. The rated torque of the auxiliary drive motor is selected to be 50% to 100% of the rated torque of the main drive motor, preferably 60% to 80%. By specifically selecting the rated torques of the main drive motor and the auxiliary drive motor, they are particularly compatible with the reducer assembly designed according to the present invention, thereby ensuring that the main drive motor and the auxiliary drive motor operate in their high-efficiency range as much as possible and ensuring high power transmission efficiency.

[0019] In a preferred embodiment of the present invention, the electric drive axle includes a controller for controlling the shift mechanism and the auxiliary drive force disengagement device. The controller is configured to implement the following drive modes: a low-speed drive mode for the main drive motor, a low-speed drive mode for the main and auxiliary drive motors, a high-speed drive mode for the main drive motor, a high-speed drive mode for the main and auxiliary drive motors, a low-speed drive mode for the auxiliary drive motor, and a high-speed drive mode for the auxiliary drive motor. By switching between various drive modes, the axle can adapt to various operating conditions, achieving power savings while ensuring power.

[0020] In a preferred embodiment of the present invention, in the auxiliary drive motor low-gear drive mode, the main drive motor outputs zero torque (e.g., shut down) and the shift mechanism is in first gear. The auxiliary drive motor can transmit power to the first-gear transmission mechanism through the coupling of the auxiliary drive force disconnecting device, and then output power through the first-gear transmission mechanism. In the auxiliary drive motor high-gear drive mode, the main drive motor outputs zero torque and the shift mechanism is in second gear. The auxiliary drive motor can transmit power to the first-gear transmission mechanism through the coupling of the auxiliary drive force disconnecting device, and then transmit power to the second-gear transmission mechanism for output. These two modes achieve power saving requirements when lightly loaded or unloaded, and at low or high speeds. Furthermore, in a preferred embodiment, when the auxiliary drive motor is used alone, the cruising speed of the electric truck is between 20 and 50 km / h, and more preferably, the road gradient is less than 1%. Under these operating conditions, using the auxiliary drive motor alone can be well adapted to the electric drive axle design of the present invention, thereby maintaining the motor's efficiency in the high-efficiency range.

[0021] Another aspect of the present invention relates to an electric truck having an electric drive axle according to the present invention. The electric truck according to the present invention has at least two axles, preferably three axles. Advantageously, the electric drive axles according to the present invention are the center axle and the rear axle. The electric truck can be a medium-duty electric truck, particularly a heavy-duty electric truck.

[0022] Overall, the electric drive axle according to the present invention balances power, economy, and space utilization. Through its various preferred embodiments, the electric drive axle or electric truck according to the present invention can further reduce energy consumption and operating costs, thereby offering greater advantages over gasoline-powered vehicles and increasing the future market penetration of electric trucks. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The above features and advantages of the present invention and the manner of achieving them are described in detail below with reference to specific embodiments and the accompanying drawings, but the present invention is not limited to the features of the specific embodiments. In the accompanying drawings:

[0024] FIG1 shows an electric drive axle according to the present invention.

[0025] FIG2 shows the low-speed driving mode of the main drive motor.

[0026] FIG3 shows the low-speed driving mode of the main drive motor and the auxiliary drive motor.

[0027] FIG4 shows the high-speed driving mode of the main drive motor.

[0028] FIG5 shows the high-speed driving mode of the main drive motor and the auxiliary drive motor.

[0029] FIG6 shows the auxiliary drive motor low gear driving mode.

[0030] FIG7 shows the auxiliary drive motor high-speed driving mode. DETAILED DESCRIPTION

[0031] To make the purpose, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the described embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0032] Unless otherwise defined, the technical or scientific terms used herein shall have the ordinary meaning understood by persons of ordinary skill in the field to which the invention belongs. The words "first", "second" and similar terms used in the patent application specification and claims of the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. Words such as "include" or "comprise" mean that the elements or objects preceding the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Front", "back", "up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the object being described changes, the relative positional relationship may also change accordingly.

[0033] The drawings in the present invention are not drawn strictly according to the actual scale. They are regarded as provisions of the present invention only when the size and position relationship are clearly stated. The specific size and quantity of each structure can be determined according to actual needs.

[0034] The present invention is generally described with reference to Figure 1. The electric drive axle comprises: a main drive motor 1; a first gear 2, which is designed as the driving gear of the main drive first-stage reduction stage; a second gear 3, which is designed as the driven gear of the main drive first-stage reduction stage; a second gear driving gear 4; a second gear driven gear 5; a right half shaft 6; a first gear sleeve 7; a third gear 9, which is designed as the driving gear of the auxiliary drive first-stage reduction stage; a fourth gear 8, which is designed as the driven gear of the auxiliary drive first-stage reduction stage; an auxiliary drive motor 10; a second shaft gear hub 11; a fifth gear 12, which is designed as the driving gear of the auxiliary drive second-stage reduction stage; a first gear driven gear 13; a differential assembly 14; a left half shaft 15; a first gear driving gear 16; an output shaft 17; an output shaft gear hub 18; a second gear sleeve 19; a first shaft 20; and a second shaft 21.

[0035] 1 , the electric drive axle includes a main drive motor, an auxiliary drive motor, a reducer assembly and a differential assembly, wherein the reducer assembly includes a main drive first-stage reduction stage, an auxiliary drive first-stage reduction stage, a first-gear transmission mechanism, a second-gear transmission mechanism and a shift mechanism, wherein the shift mechanism realizes switching between first gear, second gear and neutral gear, wherein the main drive motor transmits power to the differential assembly via the main drive first-stage reduction stage and through the first-gear transmission mechanism or the second-gear transmission mechanism, wherein the reducer assembly further includes an auxiliary drive force disengaging device, wherein the auxiliary drive motor can transmit power to the first-gear transmission mechanism via the auxiliary drive first-stage reduction stage and through the coupling of the auxiliary drive force disengaging device, and passive idling is avoided by disconnecting the auxiliary drive force disengaging device.

[0036] The main drive first reduction stage, the auxiliary drive first reduction stage, the first gear transmission mechanism, the second gear transmission mechanism, the shift mechanism, and the auxiliary drive force disengagement device are further described below.

[0037] The main drive primary reduction stage has intermeshing first and second gears. The first gear, serving as the driving gear of the primary reduction stage, is connected to the main drive motor. The second gear, serving as the driven gear of the primary reduction stage, is fixed to the first shaft. The auxiliary drive primary reduction stage has intermeshing third and fourth gears. The third gear, serving as the driving gear of the auxiliary drive primary reduction stage, is connected to the auxiliary drive motor. The fourth gear, serving as the driven gear of the auxiliary drive primary reduction stage, is rotatably supported on the second shaft (e.g., via a bearing). The fourth gear does not mesh with the second gear driven gear.

[0038] The first-gear transmission mechanism includes a first-gear driving gear and a first-gear driven gear. When first gear is engaged, the first-gear driving gear serves as the driving gear for the main drive secondary reduction stage, while the first-gear driven gear serves as the driven gear for the main drive secondary reduction stage. The second-gear transmission mechanism includes a second-gear driving gear and a second-gear driven gear. When second gear is engaged, the second-gear driving gear serves as the driving gear for the main drive secondary reduction stage, while the second-gear driven gear serves as the driven gear for the main drive secondary reduction stage. Furthermore, the first-gear driving gear and the second-gear driving gear are fixed to the first shaft, while the first-gear driven gear and the second-gear driven gear are rotatably supported on the output shaft.

[0039] The shift mechanism includes an output shaft hub, a first-gear driven gear hub, a second-gear driven gear hub, and a first gear sleeve. The first gear sleeve can be positioned solely on the output shaft hub (i.e., in neutral), or it can connect the first-gear driven gear hub to the output shaft hub (to engage first gear), and the second-gear driven gear hub to the output shaft hub (to engage second gear). This allows the main drive motor's power to be transmitted to the output shaft via only two transmission stages, resulting in highly efficient transmission. This design also offers excellent stability and space efficiency.

[0040] The auxiliary drive force disengagement device includes a fourth gear hub, a second shaft hub, a second shaft, a second gear sleeve, and a fifth gear. The second shaft hub is fixed to the second shaft, and the second gear sleeve is capable of connecting and disconnecting the fourth gear hub from the second shaft hub. The fifth gear is fixed to the second shaft and meshes with the first gear driven gear. The auxiliary drive force disengagement device not only transmits power from the auxiliary drive motor to the first gear driven gear, but also disconnects the power from the auxiliary drive motor to prevent passive idling of the auxiliary drive motor.

[0041] Referring to Figure 1, the output shaft is directly connected to the differential assembly without a reduction stage. The differential assembly is connected to the electric truck's axles, namely the left and right half-shafts, with the right half-shaft passing through the hollow-designed output shaft. The left and right half-shafts are directly connected to the wheels, meaning there is no reduction stage between the left and right half-shafts. This overall design eliminates the need for wheel-mounted reducers, reducing manufacturing and assembly costs.

[0042] Furthermore, with respect to the direction of travel, the main drive motor is located at the front of the electric drive axle, and the auxiliary drive motor is located at the rear. Furthermore, the second gear is axially arranged between the first and second gear driving gears. Furthermore, the fourth gear is axially arranged between the first and second gear driven gears. Furthermore, with respect to the radial direction of the axle, the auxiliary drive force disconnect device is located between the shift mechanism and the auxiliary drive motor. This design achieves a more compact structure.

[0043] Various driving modes are described below with reference to FIG. 2 to FIG. 7 , wherein the bold solid lines represent the paths of power transmission.

[0044] Figure 2 shows the main drive motor in low-gear mode, with the first gear sleeve shifted left (first gear engaged) and the second gear sleeve stationary (i.e., the auxiliary drive force disconnect device is disengaged). The main drive motor's power is transmitted to the wheels via the first and second gears, the first-gear driving gear, the first-gear driven gear, the output shaft hub, the output shaft, the differential, the left and right half-shafts. This ensures high power at low speeds.

[0045] Figure 3 shows the main drive motor and auxiliary drive motor in low-gear mode, with the first gear sleeve shifted to the left and the second gear sleeve shifted to the right (i.e., the auxiliary drive force disengagement device is in a coupled state). The power of the main drive motor is transmitted to the wheels via the first gear, the second gear, the first gear driving gear, the first gear driven gear, the output shaft hub, the output shaft, the differential, the left and right half-shafts. Simultaneously, the power of the auxiliary drive motor is transmitted to the wheels via the third gear, the fourth gear, the second shaft hub, the second shaft, the fifth gear, the first gear driven gear, the output shaft hub, the output shaft, the differential, the left and right half-shafts. This ensures greater power requirements at low speeds.

[0046] Figure 4 illustrates the main drive motor in high-gear mode. The first gear sleeve shifts right (second gear engaged), while the second gear sleeve remains stationary (i.e., the auxiliary drive force disengagement device is disconnected). Power from the main drive motor is transmitted to the wheels via the first and second gears, the second-gear driving gear, the second-gear driven gear, the output shaft hub, the output shaft, the differential, and the left and right half-shafts. This mode achieves power savings under light loads by fully disengaging the auxiliary drive motor, preventing it from idling and reducing energy waste.

[0047] Figure 5 shows the high-gear drive mode for the main and auxiliary drive motors. With the first gear sleeve shifted right (second gear engaged), and the second gear sleeve shifted right (i.e., the auxiliary drive force disengagement device is in the coupled state), the main drive motor's power is transmitted to the wheels via the first gear, second gear, second-gear driving gear, second-gear driven gear, output shaft hub, output shaft, differential, left and right half-shafts. Simultaneously, the auxiliary drive motor's power is transmitted to the wheels via the third gear, fourth gear, second shaft hub, second shaft, fifth gear, first-gear driven gear, first shaft, second-gear driving gear, second-gear driven gear, output shaft hub, output shaft, differential, left and right half-shafts. This mode ensures greater power requirements at high speeds.

[0048] Figure 6 illustrates the auxiliary drive motor's low-gear drive mode. The first gear sleeve shifts left (first gear engaged), the second gear sleeve shifts right (i.e., the auxiliary drive force disengagement device is in the coupled state), and the main drive motor is off. The auxiliary drive motor's power is transmitted to the wheels via the third gear, fourth gear, second shaft hub, second shaft, fifth gear, first-gear driven gear, output shaft hub, output shaft, differential, left and right half-shafts. This mode achieves power savings when the vehicle is lightly loaded or unloaded, and at low speeds.

[0049] Figure 7 shows the auxiliary drive motor in low-gear mode, in which the first gear sleeve shifts right (second gear is engaged), the second gear sleeve shifts right (i.e., the auxiliary drive force disengagement device is in the coupled state), the main drive motor is shut down, and the auxiliary drive motor's power is transmitted to the wheels via the third gear, fourth gear, second shaft hub, second shaft, fifth gear, first gear passive gear, first gear driving gear, first shaft, second gear driving gear, second gear passive gear, output shaft hub, output shaft, differential, left half-shaft, and right half-shaft. This mode achieves power saving requirements under light or no-load conditions and at high speeds. In the above two drive modes, although the main drive motor may passively idle due to the gear transmission, a separate power disengagement device is not provided. This is because, considering various operating conditions, the impact of the main drive motor's passive idling is relatively small, and from a cost perspective, a separate power disengagement device is not required. Therefore, the above design is very reasonable.

[0050] Those skilled in the art should understand that the above-mentioned specific embodiments are merely examples and not limitations, and that various modifications, combinations, partial combinations and replacements may be made to the embodiments of the present invention according to design requirements and other factors. As long as they are within the scope of the attached claims or their equivalents, they fall within the scope of rights to be protected by the present invention.

Claims

1. An electric drive axle for an electric truck, the electric drive axle having a main drive motor, an auxiliary drive motor, a reducer assembly, and a differential assembly, characterized in that The reducer assembly has a main drive first-stage reduction stage, an auxiliary drive first-stage reduction stage, a first-gear transmission mechanism, a second-gear transmission mechanism, and a shifting mechanism. The shifting mechanism realizes the switching among the first gear, the second gear, and the neutral gear. The main drive motor transmits power to the differential assembly via the main drive first-stage reduction stage and through the first-gear transmission mechanism or the second-gear transmission mechanism. The reducer assembly also has an auxiliary drive power disengaging device. The auxiliary drive motor can transmit power to the first-gear transmission mechanism via the auxiliary drive first-stage reduction stage and through the coupling of the auxiliary drive power disengaging device, and avoid passive idling through the disconnection of the auxiliary drive power disengaging device.

2. The electric drive axle according to claim 1, wherein The main drive first-stage reduction stage has a first gear and a second gear that mesh with each other. The first gear is connected to the main drive motor, and the second gear is fixed on the first shaft. The auxiliary drive first-stage reduction stage has a third gear and a fourth gear that mesh with each other. The third gear is connected to the auxiliary drive motor, and the fourth gear is rotatably supported on the second shaft. In addition, the first-gear transmission mechanism includes a first-gear driving gear and a first-gear driven gear, and the second-gear transmission mechanism includes a second-gear driving gear and a second-gear driven gear. The first-gear driving gear and the second-gear driving gear are fixed on the first shaft, and the first-gear driven gear and the second-gear driven gear are rotatably supported on the output shaft of the transmission assembly. In addition, the shifting mechanism includes an output shaft hub, a first-gear driven gear hub, a second-gear driven gear hub, and a first sleeve. The first sleeve can be located only on the output shaft hub, or can connect the first-gear driven gear hub to the output shaft hub, and connect the second-gear driven gear hub to the output shaft hub.

3. The electric drive axle according to claim 2, wherein, The auxiliary drive power disengaging device includes a fourth-gear hub, a second-shaft hub, a second shaft, a second sleeve, and a fifth gear. The second-shaft hub is fixed on the second shaft, and the second sleeve can connect or disconnect the fourth-gear hub to the second-shaft hub. The fifth gear is fixed on the second shaft and meshes with the first-gear driven gear.

4. The electric drive axle according to claim 2, wherein The output shaft is directly connected to the differential assembly, and the differential assembly is connected to the left half shaft and the right half shaft of the electric truck. The right half shaft passes through the output shaft designed as a hollow shaft. The left half shaft and the right half shaft are directly connected to the corresponding wheels respectively.

5. The electric drive axle according to claim 3, characterized in that, The second gear is axially arranged between the first-gear driving gear and the second-gear driving gear. In addition, the fourth gear is axially arranged between the first-gear driven gear and the second-gear driven gear. In addition, with reference to the radial direction of the axle, the auxiliary drive power disengaging device is arranged between the shifting mechanism and the auxiliary drive motor. In addition, with reference to the driving direction, the main drive motor is arranged on the front side of the electric drive axle, and the auxiliary drive motor is arranged on the rear side of the electric drive axle.

6. The electric drive axle according to claim 1, characterized in that, The rated torque of the main drive motor is greater than 1000 Nm, and the rated torque of the auxiliary drive motor does not exceed the rated torque of the main drive motor.

7. The electric drive axle according to claim 1, wherein The main drive motor, the auxiliary drive motor, the reducer assembly, and the differential assembly are arranged in a common housing.

8. The electric drive axle according to claim 1, characterized in that, The electric drive axle has a controller for controlling the shifting mechanism and the auxiliary drive power disengaging device. The controller is configured to be able to implement the following driving modes: the main drive motor low-gear driving mode, the main drive motor and the auxiliary drive motor low-gear driving mode, the main drive motor high-gear driving mode, the main drive motor and the auxiliary drive motor high-gear driving mode, the auxiliary drive motor low-gear driving mode, and the auxiliary drive motor high-gear driving mode.

9. The electric drive axle according to claim 8, wherein In the low gear driving mode of the auxiliary drive motor, the main drive motor outputs zero torque and the shifting mechanism is shifted into the first gear. The auxiliary drive motor can transmit power to the first gear transmission mechanism through the coupling of the auxiliary driving force disengaging device, and then output the power through the first gear transmission mechanism. In the high gear driving mode of the auxiliary drive motor, the main drive motor outputs zero torque and the shifting mechanism is shifted into the second gear. The auxiliary drive motor can transmit power to the first gear transmission mechanism through the coupling of the auxiliary driving force disengaging device, and then transmit it to the second gear transmission mechanism to output the power. Moreover, when the auxiliary drive motor is used alone, the cruising speed of the electric truck is between 20 and 50 kilometers per hour.

10. An electric truck, characterized in that, The electric truck has an electric drive axle according to any one of claims 1 to 9.

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