Axle system

Abstract

This invention relates to an axle system. The axle system includes a planetary gear set, comprising: a first sun gear; first planet gears meshing with the first sun gear; a second planet gear torsionally connected to the first planet gear along the same axis of rotation; a ring gear arranged along the same axis of rotation as the first sun gear; a planet carrier mounted on the second planet gear and arranged along the same axis of rotation as the first sun gear; and a second sun gear meshing with the second planet gear and arranged along the same axis of rotation as the first sun gear. The torque of the axle system can be input to the planetary gear set from the first sun gear and can be selectively output through the planet carrier or the second sun gear. The axle system of this invention can achieve a two-stage transmission function with a large gear ratio in a simple and compact layout.

Description

Technical Field

[0001] This invention relates to the field of vehicle technology. Specifically, this invention relates to an axle system for motor vehicles. Background Technology

[0002] The axle system is a crucial component of modern automobiles. It transmits the torque generated by the internal combustion engine or electric motor to the wheels, driving them to rotate and propelling the vehicle forward. The engine, transmission, and differential can all be integrated into the axle system. Typically, engines, especially electric motors, operate at very high speeds, necessitating speed reduction and torque amplification via transmissions or similar mechanisms within the axle system to achieve suitable output speeds at the wheels.

[0003] To achieve large transmission ratios and multi-speed changes, axle systems often feature complex layouts consisting of multiple drive shafts, numerous gear pairs, and synchronizers. For example, CN 104057821B discloses a powertrain assembly for a two-speed electric vehicle driven by an electric motor. The synchronizer selectively connects the differential housing to the sun gear of a planetary gear set or the output shaft of the motor, thereby achieving speed changes. In this layout, the transmission ratio is insufficient because the motor's output torque passes through a limited number of gear sets along the transmission path. Adding more gear sets requires more parallel drive shafts, further increasing the system's space requirements. The motor's output shaft is parallel to the differential's half-shaft, which further reduces the structure's compactness and integration. Furthermore, the synchronizer used to select the transmission path is complex, space-consuming, and expensive. Summary of the Invention

[0004] Therefore, the technical problem to be solved by the present invention is to provide an axle system that can realize a speed change function with a large transmission ratio in a simple and compact layout.

[0005] The aforementioned technical problem is solved by an axle system according to the present invention. This axle system includes a planetary gear set for transmitting torque, comprising: a first sun gear; first planet gears meshing with the first sun gear; second planet gears anti-torsively connected to the first planet gears along the same axis of rotation; a fixed ring gear arranged along the same axis of rotation as the first sun gear; a planet carrier mounted on the second planet gears and arranged along the same axis of rotation as the first sun gear; and a second sun gear meshing with the second planet gears and arranged along the same axis of rotation as the first sun gear. Depending on the specific needs of the transmission ratio and spatial layout, the ring gear can, for example, be fixed to the transmission housing of the axle system and can mesh with either of the two planet gears. In the above-described axle system structure, a unique double planetary gear set is formed, which has two sun gears arranged coaxially and a pair of planet gears anti-torsively connected. The torque of the axle system is input into the planetary gear set from the first sun gear. The first sun gear drives the first planet gear and the second planet gear to rotate together, and the second planet gear then drives the planet carrier and transmits the torque to the second sun gear. Ultimately, either the planet carrier or the second sun gear can be chosen as the output end of the planetary gear set, thereby obtaining different transmission ratios.

[0006] In the aforementioned transmission layout, the transmission ratio between the input and output ends of the planetary gear set is determined by multiple transmission ratios along the entire transmission path: when torque is output from the second sun gear, it is determined by the transmission ratio between the first sun gear and the first planet gear, and the transmission ratio between the second planet gear and the second sun gear; when torque is output from the planet carrier, it is determined by the transmission ratio between the first sun gear and the first planet gear, and the transmission ratio between the second planet gear and the planet carrier. This provides a transmission ratio far greater than that of conventional planetary gear sets, and its overall structure is centrally symmetrical, eliminating the need for an additional drive shaft, thus significantly saving radial layout space. Simultaneously, the direct torsional connection between the paired planet gears also allows for a very compact axial layout. Preferably, the first and second planet gears can be integrally formed to simplify installation procedures, reduce the number of components, and improve system integration. However, alternative torsional connection methods such as spline connections or welding can be used as needed.

[0007] According to a preferred embodiment of the invention, the axle system may further include a dual clutch arranged coaxially with the second sun gear. The dual clutch includes an outer engagement hub and a first and second inner engagement hub capable of selectively engaging with the outer engagement hub in a torsionally resistive manner. The first inner engagement hub is torsionally connected to the second sun gear, and the second inner engagement hub is torsionally connected to the planet carrier. The outer engagement hub and the two inner engagement hubs together constitute a dual-clutch synchronizing mechanism capable of selectively outputting torque from either the planet carrier or the second sun gear. This dual clutch can, for example, take the form of a common wet clutch or other clutches. Compared to conventional synchronizers, the dual-clutch synchronizing mechanism is coaxially arranged with the planetary gear set and has a simpler structure, thus saving layout space and cost.

[0008] According to another preferred embodiment of the invention, the axle system may further include a differential connected to the outer engagement hub for outputting torque to the wheels and allowing different speeds to be obtained on the two wheels. Preferably, the differential may be arranged coaxially with the dual clutch, thereby reducing the number of drive shafts and optimizing radial layout space. In this case, due to the use of a dual-clutch synchronization mechanism, the outer engagement hub may preferably be directly fixed to the differential housing, and may further preferably be integrally formed with the differential housing. This can significantly save axial layout space in the axle system. Furthermore, one half-shaft of the differential may pass coaxially through the cavities of the first and second sun gears without contacting the first and second sun gears, thereby transmitting the differentialized torque to one wheel.

[0009] According to another preferred embodiment of the invention, the differential can also be arranged on another axis parallel to the rotation axis of the two sun gears. In this case, the outer engagement hub can be connected to the differential via a gear set, thereby obtaining an additional transmission ratio through the gear set.

[0010] According to another preferred embodiment of the invention, the ring gear of the planetary gear set can mesh with the second planetary gear, and the diameter of the first planetary gear is larger than the diameter of the second planetary gear. In this case, the first planetary gear does not engage with the ring gear. Since the speed directly output from the vehicle engine is generally high, it is usually desirable to achieve a speed reduction and torque increase effect through the transmission path of the axle system. For this reason, in the gear set composed of the first sun gear and the first planetary gear, the diameter of the first planetary gear, which is the output end, is generally larger, while in the gear set composed of the second planetary gear and the second sun gear, the diameter of the second planetary gear, which is the input end, is generally smaller. Therefore, in a pair of planetary gears arranged coaxially, the space on the radially outer side of the second planetary gear is relatively large, and the engagement of the ring gear with the second planetary gear helps to save radial layout space.

[0011] According to another preferred embodiment of the present invention, the axle system may further include a motor, which serves as the power input mechanism of the axle system, and its output end is torsionally connected to the first sun gear along the same axis of rotation. Since the axle system of the present invention is a two-speed transmission system, it is particularly suitable for electric vehicles. Attached Figure Description

[0012] The invention is further described below with reference to the accompanying drawings. In the drawings, the same reference numerals represent elements with the same function. Wherein:

[0013] Figure 1 This is a schematic diagram of the structure of an axle system according to an embodiment of the present invention;

[0014] Figure 2a and Figure 2b They are Figure 1 A schematic diagram of the torque transmission path of the CRRC axle system in different gears; and

[0015] Figure 3 This is a schematic diagram of the structure of a vehicle axle system according to another embodiment of the present invention. Detailed Implementation

[0016] The following describes specific embodiments of the axle system according to the present invention in conjunction with the accompanying drawings. The detailed description and drawings below are provided to illustrate the principles of the invention, and the invention is not limited to the described preferred embodiments; the scope of protection of the invention is defined by the claims.

[0017] According to an embodiment of the present invention, an axle system for a two-speed transmission vehicle is provided. This axle system can be applied to various motor vehicles, and is particularly suitable for electric vehicles.

[0018] Figure 1 A schematic diagram of an axle system according to an embodiment of the present invention is shown. As shown, the axle system includes a motor as a power mechanism, a planetary gear set and a dual clutch as a gearbox, and a differential 11. The motor includes a stator 1, a rotor 2, and a motor output shaft 3. The stator 1 is fixed to a motor housing (not shown), for example. The rotor 2 and the motor output shaft 3 are arranged radially inside the stator 1 along the same axis of rotation and are capable of rotating integrally relative to the stator 1. One end of the motor output shaft 3 extends out of the motor housing.

[0019] The planetary gear set of this axle system is a double planetary gear set, which includes a first sun gear 14, a second sun gear 9, a ring gear 5, and a planet carrier 7 arranged along the same axis of rotation, and also includes one or more pairs of first planet gears 4 and second planet gears 6 arranged in pairs. The first sun gear 14 is torsionally connected to the end of the motor output shaft 3 extending out of the motor housing along the same axis of rotation; preferably, the two can be integrally formed. One or more first planet gears 4 are distributed radially outside the first sun gear 14 in the circumferential direction and mesh with the first sun gear 14 respectively. Each first planet gear 4 is torsionally connected to a corresponding second planet gear 6 along the same axis of rotation; preferably, each pair of first planet gears 4 and second planet gears 6 can be integrally formed. The second planet gear 6 is located axially on the side of the first planet gear 4 opposite to the motor. Each pair of first planet gears 4 and second planet gears 6 is rotatably supported on the planet carrier 7. An annular ring gear 5 is fixed radially outside the second planet gear 6 to, for example, a transmission housing (not shown) and meshes with each second planet gear 6. The second sun gear 9 is located on the side of the first sun gear 14 facing away from the motor, and meshes with each of the second planet gears 6 radially inward. To achieve a larger transmission ratio for speed reduction and torque increase, in the gear set consisting of the first sun gear 14 and the first planet gear 4, the diameter of the first planet gear 4 (as the output end) is larger, while in the gear set consisting of the second planet gears 6 and the second sun gear 9, the diameter of the second planet gear 6 (as the input end) is smaller. Therefore, in a pair of coaxially arranged planet gears, the diameter of the second planet gear 6 is designed to be smaller than that of the first planet gear 4, and the ring gear 5 meshes with the second planet gear 6, which helps to save radial layout space.

[0020] The dual-clutch axle system includes a first inner engagement hub 12, a second inner engagement hub 13, and an outer engagement hub 8, all arranged along the same axis of rotation as the planetary gear set (i.e., along the same axis of rotation as the two sun gears and consequently the motor output shaft 3). Driven by a drive mechanism (not shown), the two inner engagement hubs can each move axially, selectively engaging or disengaging with the outer engagement hub 8 under torsion. Specifically, the first inner engagement hub 12 is torsionally connected to the second sun gear 9, the second inner engagement hub 13 is torsionally connected to the planetary carrier 7, and the outer engagement hub 8 is torsionally connected to the differential 11 housing. In this configuration, the differential 11 is also arranged along the same axis of rotation as the motor and the planetary gear set. Preferably, the first inner engagement hub 12 and the second sun gear 9, the second inner engagement hub 13 and the planetary carrier 7, and the outer engagement hub 8 and the differential 11 housing can be integrally formed.

[0021] The differential 11 includes two half-shafts 10 and 15, which enable torque to be transmitted to the left and right wheels at different speeds. Half-shaft 15 passes sequentially through the second sun gear 9 and the first sun gear 14 of the planetary gear set and the cavity in the motor output shaft 3 along the axis of the axle system, without contacting these structures, thus enabling torque output to the wheel on that side with the same axis of rotation.

[0022] Figure 2a and Figure 2b Arrows illustrate the torque transmission paths of the aforementioned axle system in two different gears. For example... Figure 2a As shown, when the second inner engagement hub 13 and the outer engagement hub 8 are engaged torsionally, the first inner engagement hub 12 disengages from the outer engagement hub 8. The torque output by the motor is first transmitted to the first planetary gear 4 through the first sun gear 14, then to the planet carrier 7 through the second planetary gear 6, and finally input to the differential 11 through the second inner engagement hub 13 and the outer engagement hub 8. Figure 2b As shown, when the first inner engagement hub 12 and the outer engagement hub 8 are engaged torsionally, the second inner engagement hub 13 disengages from the outer engagement hub 8. The torque output by the motor is first transmitted to the first planetary gear 4 through the first sun gear 14, then to the second sun gear 9 through the second planetary gear 6, and finally input to the differential 11 through the first inner engagement hub 12 and the outer engagement hub 8. This design integrates two sets of planetary gears and two sun gears within the same planetary gear set, increasing the number of transmission stages and achieving a larger transmission ratio while significantly shortening the axial length of the system. Simultaneously, the coaxial arrangement of the motor, planetary gear set, and differential in this system reduces the number of support shafts and shortens the radial dimension of the system. Furthermore, the use of a dual-clutch synchronization mechanism further simplifies the system structure, reduces costs, and avoids torque transmission interruption during gear shifts.

[0023] Figure 3 Another embodiment according to the present invention is shown. This embodiment is related to... Figure 1 The only difference in the embodiment shown is the arrangement of the differential 11. Figure 3 As shown, the differential 11 is arranged on another axis parallel to the motor, planetary gear set, and dual clutch. A first gear 16 is torsionally connected to the outer engagement hub 8 on the side facing away from the planetary gear set, along with the axis of rotation. A second gear 17 is fixed to the housing of the differential 11 along the axis of rotation. The first gear 16 and the second gear 17 mesh with each other, thereby transmitting the output torque of the outer engagement hub 8 to the housing of the differential 11. The first gear 16 and the second gear 17 can further provide additional gear ratios, thus achieving a more flexible gear ratio design.

[0024] While possible embodiments have been described exemplarily in the foregoing description, it should be understood that numerous variations of embodiments exist through combinations of all known and readily conceived technical features and implementation methods. Furthermore, it should be understood that the exemplary embodiments are merely examples and do not in any way limit the scope, application, or construction of the invention. The foregoing description is more intended to provide those skilled in the art with technical guidance for transforming at least one exemplary embodiment, wherein various changes, particularly regarding the function and structure of the components, can be made without departing from the scope of the claims.

[0025] Appendix Label Table

[0026] 1. Stator

[0027] 2 rotors

[0028] 3. Motor output shaft

[0029] 4 First Planetary Gear

[0030] 5 Gear Ring

[0031] 6 Second Planetary Gear

[0032] 7 Planetary Carrier

[0033] 8. External coupling hub

[0034] 9. Second Sun Wheel

[0035] 10 half-shafts

[0036] 11. Differential

[0037] 12 First inner joint hub

[0038] 13 Second inner joint hub

[0039] 14 First Sun Wheel

[0040] 15 half-shafts

[0041] 16 First Gear

[0042] 17 Second Gear

Claims

1. An axle system comprising a planetary gear set, characterized in that, The planetary gear set includes: First sun wheel (14); The first planetary gear (4) meshes with the first sun gear (14); The second planetary gear (6) is torsionally connected to the first planetary gear (4) along the same axis of rotation; A gear ring (5) is fixed and arranged along the same axis of rotation as the first sun gear (14), and the gear ring (5) meshes with one of the first planet gear (4) and the second planet gear (6); Planet carrier (7), which is mounted on the second planetary gear (6) and arranged on the same axis of rotation as the first sun gear (14); and The second sun gear (9) meshes with the second planet gear (6) and is arranged on the same axis of rotation as the first sun gear (14); The torque of the axle system can be input into the planetary gear set from the first sun gear (14) and can be selectively output through the planet carrier (7) or the second sun gear (9).

2. The axle system according to claim 1, characterized in that, The axle system also includes a dual clutch arranged on the same axis of rotation as the second sun gear (9). The dual clutch includes an outer engagement hub (8) and a first inner engagement hub (12) and a second inner engagement hub (13) that can selectively engage with the outer engagement hub (8) in a torsion manner. The first inner engagement hub (12) is torsionally connected to the second sun gear (9), and the second inner engagement hub (13) is torsionally connected to the planet carrier (7).

3. The axle system according to claim 2, characterized in that, The axle system also includes a differential (11) that is connected to the outer coupling hub (8) via a transmission.

4. The axle system according to claim 3, characterized in that, The differential (11) is arranged on the same axis of rotation as the dual clutch.

5. The axle system according to claim 4, characterized in that, The outer coupling hub (8) is fixed to the housing of the differential (11).

6. The axle system according to claim 4, characterized in that, One half-shaft (15) of the differential (11) passes through the cavity of the first sun gear (14) and the second sun gear (9) along the axis of rotation.

7. The axle system according to claim 2, characterized in that, The outer coupling hub (8) is connected to the differential (11) via a gear set.

8. The axle system according to claim 1, characterized in that, The gear ring (5) meshes with the second planetary gear (6), and the diameter of the first planetary gear (4) is larger than the diameter of the second planetary gear (6).

9. The axle system according to claim 1, characterized in that, The first planetary gear (4) and the second planetary gear (6) are integrally formed.

10. The axle system according to any one of claims 1 to 9, characterized in that, The axle system also includes a motor (1), the output end of which is torsionally connected to the first sun gear (14) along the same axis of rotation.

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