Electric drive axle and electric truck

Abstract

An electric drive axle, comprising a unique driving electric motor (1), a reducer assembly and a differential assembly (13), wherein the reducer assembly is provided with a first reduction stage, a first-gear transmission mechanism, a second-gear transmission mechanism and a power takeoff, the first-gear transmission mechanism is provided with a first-gear shifting mechanism for switching between a neutral gear and the first gear, the second-gear transmission mechanism is provided with a second-gear shifting mechanism for engaging and disengaging the second gear, the first-gear shifting mechanism is arranged between an axle and the driving electric motor, the second-gear shifting mechanism is arranged coaxial to the axle, and the second-gear transmission mechanism is in direct transmission connection with the power takeoff. The electric drive axle has the dynamic property, the economical efficiency, the space utilization rate and the power takeoff efficiency. Further disclosed is an electric truck comprising the electric drive axle.

Description

e-axles and electric trucks

[0001] This application claims priority to Chinese patent application No. 202310602868.8 filed on May 26, 2023, 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 invention relates to an electric drive axle and an electric truck. Background Art

[0003] For electric axles in electric trucks, such as those used in medium- and heavy-duty electric trucks, the current market-proven solution uses a fixed-ratio reducer. This solution results in low-speed torque at low motor speeds, failing to meet the hill-climbing requirements of heavy trucks and resulting in low vehicle power. At high speeds, the motor cannot operate in its economical range due to power constraints, increasing power consumption and poor vehicle economy. This significantly reduces the truck's transport efficiency, shortens its range, and increases its operating costs. This approach, in turn, hinders 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 differential's large footprint, necessitating a more efficient speed reducer. Numerous electric axle designs for passenger cars are known, but these differ significantly from those for electric trucks in many respects, such as the presence of a balancing suspension and leaf springs on the chassis of electric trucks. Therefore, passenger car axles are generally not directly transferable to electric trucks. Regarding electric truck axles, particularly those with power take-offs, various speed reducer designs are known. However, many of these designs remain at the theoretical level, often failing to consider the size and efficiency of the gears in the actual reduction stages. This makes them difficult to implement, and the transmission path and efficiency of the power take-off cannot be guaranteed. For example, in one known design, the speed reducer has three forward gears, all located on a central shaft, and features a central planetary gear transmission. Furthermore, the input force is transmitted to the power take-off via a four-stage transmission. However, this design, with three gears and a planetary gear transmission mounted on the central shaft, results in a speed reducer with excessive axial dimensions, making it virtually impossible to install within the electric axle of an electric truck. Furthermore, the power take-off's power transmission efficiency is poor. Another known design employs a fixed-ratio speed reducer in the electric axle. While shifting elements can transfer power input to the power take-off, this cuts off power transmission to the wheels, preventing power take-off during driving. Consequently, no ideal solution currently exists that balances power, economy, space utilization, and power take-off efficiency.

[0005] Summary of the Invention

[0006] 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.

[0007] The electric drive axle according to the present invention is used for an electric truck. The electric drive axle has a single drive motor, a reducer assembly and a differential assembly. The reducer assembly has a first reduction stage, a first-gear transmission mechanism, a second-gear transmission mechanism and a power take-off. The first-gear transmission mechanism has a first-gear shift mechanism for switching between neutral and first gear, and the second-gear transmission mechanism has a second-gear shift mechanism for engaging and disengaging the second gear. The first-gear shift mechanism is arranged between the axle and the drive motor, the second-gear shift mechanism is arranged coaxially with the axle, and the second-gear transmission mechanism is directly connected to the power take-off.

[0008] The electric drive axle of the present invention allows the motor to disengage power transmission when in neutral, thereby resolving the energy loss caused by the motor's passive idling during high-speed coasting. By utilizing a high-speed gear (second gear) and a low-speed gear (first gear), the electric truck's ability to climb grades at low speeds is ensured, while also ensuring that the drive motor operates more within the economical or high-efficiency zone when traveling at high speeds. Within the scope of the present invention, the high-efficiency zone of the electric truck's drive motor is set between 90% and 96%, more preferably between 94% and 96%. Therefore, in the actual operation of the electric truck, it provides better power and economy, adapting to a wider range of road conditions while also reducing energy consumption and thus operating costs. Furthermore, the electric drive axle of the present invention can reduce manufacturing difficulty during product manufacturing and better utilize the limited space on the axle during product installation, thereby reducing manufacturing and installation costs. Furthermore, the electric drive axle of the present invention not only meets the above requirements but also ensures a high power transmission efficiency of the power take-off. At the same time, the physical structure of the power take-off is more advantageous in terms of spatial layout. Therefore, the electric drive axle of the present invention takes into account power, economy, space utilization and power take-off efficiency.

[0009] In an embodiment of the present invention, the first reduction stage is composed of a first reduction driving gear and a first reduction driven gear that mesh with each other, and the motor shaft of the drive motor is connected to the first reduction driving gear. The first gear transmission mechanism includes a first gear driving gear and a first gear driven gear that mesh with each other, the first gear driving gear is supported on the shaft of the first reduction driven gear via a bearing, and the first gear driven gear is fixedly supported on a hollow shaft. The second gear transmission mechanism includes a second gear driving gear and a second gear driven gear that mesh with each other, the second gear driving gear is fixedly connected to the first reduction driven gear, and the second gear driven gear is supported on the hollow shaft via a bearing. The hollow shaft is arranged coaxially with the axle and is connected to the differential assembly for outputting power to the wheels through the differential. The first gear shift mechanism includes a gear hub of the first gear driving gear, a first gear gear hub, and a first gear gear sleeve, and the gear hub of the first gear driving gear and the first gear gear hub can be engaged or disengaged via the first gear gear sleeve. The second-speed shift mechanism includes a gear hub for the second-speed driven gear, a second-speed gear hub fixedly connected to the hollow shaft, and a second-speed gear sleeve. The gear hub and the second-speed gear hub of the second-speed driven gear are engaged or disengaged via the second-speed gear sleeve. The power take-off (PTO) includes a PTO gear, a gear hub for the PTO gear, an output shaft gear, and a PTO engagement sleeve. The gear hub and the output shaft gear are engaged or disengaged via the PTO engagement sleeve, and the PTO gear meshes with the second-speed driven gear. The PTO's output shaft is capable of outputting power. When the electric truck is stationary, neutral is engaged, and the PTO engagement sleeve engages, allowing the PTO to output power through a three-stage transmission. When the electric truck is moving, first gear can be engaged, and the PTO engagement sleeve engages, similarly allowing the PTO to output power through a three-stage transmission. When the electric truck is moving, second gear can be engaged, and the PTO engagement sleeve engages, similarly allowing the PTO to output power through a three-stage transmission. Therefore, the PTO can output power in neutral, first gear, and second gear. In addition, the output shaft of the power take-off can be connected to a hydraulic pump, the hydraulic pump transmits hydraulic fluid to a hydraulic motor through a hydraulic oil pipe, and the hydraulic motor can be connected to an external device.

[0010] In one embodiment, the axle is connected to the wheel via a corresponding wheel-mounted reduction assembly. Because the wheel-mounted reduction assembly handles some of the speed reduction, the transmission ratio of the reducer assembly can be reduced, further reducing the actual size of the reducer assembly and lowering manufacturing costs. Therefore, when the reducer assembly according to the present invention is used in combination with the wheel-mounted reduction assembly, the aforementioned advantages of the present invention can be further realized.

[0011] In one embodiment, the first gear shift mechanism is arranged between the differential assembly and the drive motor in the radial direction of the axle, thereby achieving a more compact structural arrangement and making full use of the space in the reducer housing.

[0012] In one embodiment, the second-gear hub is positioned between the first-gear driven gear and the second-gear driven gear. Furthermore, the power take-off and the second-gear hub are axially located on the same side of the second-gear driven gear. This design achieves a more compact structure and fully utilizes the space within the reducer housing.

[0013] In one embodiment, the drive motor, reducer assembly, and differential assembly are arranged in a common reducer housing. This allows for a very compact layout and keeps the axial dimension of the reducer housing very small, thus achieving very high utilization of the limited space in the electric drive axle.

[0014] Another aspect of the present invention relates to an electric truck having the electric drive axle according to the present invention.

[0015] Overall, the electric axle and electric truck according to the present invention address the challenge of simultaneously balancing power, economy, space utilization, and power takeoff efficiency in electric drive systems. Through the various preferred embodiments of the present invention, the electric axle and electric truck according to the present invention can further reduce energy consumption and operating costs, as well as manufacturing and installation costs. This offers significant advantages over existing gasoline-powered vehicles and increases the future market penetration of electric trucks. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] 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:

[0017] FIG1 shows a schematic diagram of an electric drive axle according to the present invention. DETAILED DESCRIPTION

[0018] FIG1 illustrates an electric drive axle according to a specific embodiment of the present invention. The electric drive axle comprises a single drive motor 1, a reducer assembly (including various reduction stages), and a differential assembly 13. The motor shaft of the drive motor 1 is directly connected to a first-speed reduction driving gear 2, which meshes with a first-speed reduction driven gear 3. A second-speed driving gear 4 and a first-speed gear hub 17 are fixedly connected to the shaft of the first-speed reduction driven gear 3. A first-speed driving gear 15 is supported on the shaft of the first-speed reduction driven gear 3 via a bearing. The gear hub of the first-speed driving gear 15 can engage or disengage with the first-speed gear hub 17 via a first-speed gear sleeve 16. The first-speed driving gear 15 meshes with the first-speed driven gear 12, which is fixed to a hollow shaft 20. The hollow shaft 20 is connected to the differential assembly 13 for outputting power to the vehicle axles.

[0019] In the embodiment shown in Figure 1, the hollow shaft is rotatably supported on the right half shaft 6 of the axle, the differential assembly 13 is directly connected to the right half shaft 6 and the left half shaft 14 of the axle, and the left half shaft and the right half shaft are respectively connected to their respective wheel-side reduction assemblies 7.

[0020] In the embodiment shown in Figure 1, the second-gear driving gear 4 meshes with the second-gear driven gear 5. The second-gear driven gear is supported on a hollow shaft 20 via a bearing. The gear hub of the second-gear driven gear can be engaged or disengaged with the second-gear gear hub 11 fixed to the hollow shaft via the second-gear gear sleeve. Therefore, the movement of the first-gear gear sleeve and the second-gear gear sleeve allows the gear to be engaged in neutral, first gear, and second gear.

[0021] In the embodiment shown in Figure 1, the second-gear driven gear 5 meshes with the power take-off gear 8, which is supported on the output shaft 18 of the power take-off via a bearing. The hub of the power take-off gear and the output shaft gear 19 can be engaged or disengaged via the power take-off gear sleeve 9. Therefore, when the electric truck is stationary, the neutral gear is engaged, and the power take-off outputs power through a three-stage transmission. When the electric truck is moving, the power take-off can output power regardless of whether the first or second gear is engaged. In addition, unlike the schematic diagram shown in Figure 1, the power take-off can be arranged on the left side of the second-gear driven gear, which can also make the layout more compact.

[0022] In the actual layout of this embodiment, the first-gear shift mechanism (comprising the first-gear driving gear 15, the first-gear hub 17, and the first-gear sleeve 16) is radially arranged between the differential assembly and the drive motor. Furthermore, the schematic diagram of this embodiment does not show the complete reducer housing. In the actual layout, the drive motor, reducer assembly, and differential assembly are housed in a common reducer housing. This allows for a very compact layout and minimizes the axial dimensions of the reducer housing, effectively utilizing the limited space available within the electric drive axle.

[0023] In the scope of the present invention, the directions “left” and “right” are only used to describe the names of components, and do not limit the actual directions.

[0024] 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, the electric drive axle having a unique drive motor, a reducer assembly and a differential assembly, characterized in that: The reducer assembly comprises a primary reduction stage, a first gear transmission mechanism, a second gear transmission mechanism and a power take-off, wherein the first gear transmission mechanism comprises a first gear shift mechanism for switching between neutral and first gear, and the second gear transmission mechanism comprises a second gear shift mechanism for engaging and disengaging the second gear, wherein the first gear shift mechanism is arranged between the axle and the drive motor, the second gear shift mechanism is arranged coaxially with the axle, and the second gear transmission mechanism is directly connected to the power take-off.

2. The electric drive axle according to claim 1, characterized in that: The first reduction stage is composed of a first reduction driving gear and a first reduction driven gear that mesh with each other. The motor shaft of the drive motor is connected to the first reduction driving gear. The first gear transmission mechanism includes a first gear driving gear and a first gear driven gear that mesh with each other. The first gear driving gear is supported on the shaft of the first reduction driven gear through a bearing, and the first gear driven gear is fixedly supported on a hollow shaft. The second gear transmission mechanism includes a second gear driving gear and a second gear driven gear that mesh with each other. The second gear driving gear is fixedly connected to the first reduction driven gear, and the second gear driven gear is supported on a hollow shaft through a bearing. The hollow shaft is coaxially arranged with the axle and connected to the differential assembly, and is used to output power to the wheels through the differential.

3. The electric drive axle according to claim 2, characterized in that: The first gear shift mechanism includes a gear hub of a first gear driving gear, a first gear gear hub and a first gear gear sleeve. The gear hub of the first gear driving gear and the first gear gear hub can be engaged or disengaged through the first gear gear sleeve. The second gear shift mechanism includes a gear hub of a second gear driven gear, a second gear gear hub fixedly connected to the hollow shaft, and a second gear gear sleeve. The gear hub of the second gear driven gear and the second gear hub can be engaged or disengaged through the second gear gear sleeve.

4. The electric drive axle according to claim 2, characterized in that: The power take-off includes a power take-off gear, a gear hub of the power take-off gear, an output shaft gear and a power take-off engaging gear sleeve. The gear hub of the power take-off gear and the output shaft gear are engaged or disengaged through the power take-off engaging gear sleeve. The power take-off gear is meshed with the second gear driven gear. The output shaft of the power take-off can be connected to a hydraulic pump. The hydraulic pump transmits hydraulic fluid to a hydraulic motor through a hydraulic oil pipe. The hydraulic motor can be connected to an external device.

5. The electric drive axle according to claim 1, characterized in that: The axle is connected to the wheels through the corresponding wheel reduction assembly.

6. The electric drive axle according to claim 1, characterized in that: The first gear shift mechanism is arranged between the differential assembly and the drive motor in the radial direction of the axle.

7. The electric drive axle according to claim 3, characterized in that: The second gear gear hub is arranged between the first gear driven gear and the second gear driven gear.

8. The electric drive axle according to claim 1, characterized in that: The drive motor, the reduction gear assembly and the differential assembly are arranged in a common reduction gear housing.

9. An electric truck, characterized in that: The electric truck has the electric drive axle according to any one of claims 1 to 8.

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