Planetary gear reducer and vehicle

Abstract

The utility model relates to a planetary gear reducer for a vehicle, which comprises a shell and a planetary gear device, the shell is provided with a fixing groove used for fixing the planetary gear device, the planetary gear device is provided with a gear ring and a planet wheel, the gear ring is provided with an inner tooth part meshed with the planet wheel and a fixing part used for rotatably fixing the planetary gear device, the internal tooth portion is designed as helical teeth, the fixing portion has a protruding piece inserted into the fixing groove, the central axis of the protruding piece has an inclination angle with respect to the axis of the planetary gear device, and the inclination angle is opposite to the rotation angle of the internal tooth portion. The utility model aims to solve the problem that in the prior art, axial force exists in a gear, so that a clamping ring falls off and loses efficacy, and light weight and reliability improvement of a transmission system are achieved.

Description

Technical Field

[0001] This utility model relates to the field of vehicle transmission system technology, and specifically to the optimized design of the gear ring connection structure for a planetary gear reducer. Background Technology

[0002] In planetary gear systems, if torque is transmitted between gears via spur teeth, problems such as low overlap and poor operational balance arise, leading to higher noise levels in the planetary gear reducer. Therefore, for planetary gear systems used in vehicles, helical teeth are typically used to transmit torque for NVH (noise, vibration, and harshness) considerations. This means the ring gear and planetary gears are connected by helical teeth for anti-torsional connection. Due to the meshing geometry of helical teeth, the ring gear and planetary gears generate significant axial forces when transmitting torque. Traditional solutions involve adding a retainer ring to the housing to prevent axial movement of the ring gear. However, under high loads, frequent reversing, or extreme conditions (such as in off-road vehicles), the accumulated axial forces can easily overload the retainer ring, causing plastic deformation or even detachment from the mounting slot, leading to axial displacement of the ring gear and the risk of transmission failure. Furthermore, the reliance on retainer rings not only increases the number of parts and assembly steps but also raises maintenance costs and structural complexity. Utility Model Content

[0003] The technical problem to be solved by this utility model is to provide an improved planetary gear reducer for vehicles, which can overcome the problems in the prior art and ensure that the planetary gear device will not easily move in the axial direction with a simple structure and low cost.

[0004] The aforementioned technical problem is solved by an improved planetary gear reducer for vehicles, comprising a housing and a planetary gear assembly. The housing has a retaining groove on its radially inner side for fixing the planetary gear assembly. The planetary gear assembly has a ring gear and planetary gears. The ring gear has internal teeth that mesh with the planetary gears and a retaining part for rotational fixation in the retaining groove. The internal teeth are designed as helical teeth, and the retaining part is a protrusion inserted into the retaining groove. The core improvement of this invention lies in the fact that the central axis of the protrusion has an inclination angle relative to the axis of the planetary gear assembly, and this inclination angle is opposite to the rotation angle of the internal teeth. Through the mechanical cancellation effect of the opposite rotation angle, the axial forces generated by the meshing of the internal and external components of the ring gear reducer are theoretically balanced, and the total axial resultant force approaches zero. This solution can completely eliminate the risk of axial displacement caused by the internal meshing of the helical teeth of the ring gear in the prior art, thus eliminating the need to rely entirely on the traditional retaining ring limiting structure, simplifying the overall structure of the gearbox, reducing manufacturing costs and assembly complexity, and significantly improving the reliability of the transmission system. According to this invention, the opposite angle means that the deviation direction of the centerline of the component from the system axis is opposite. More specifically, the rotation angle of the helical teeth in the gear ring refers to the angle between the helix of the helical teeth and the gear axis. If this angle is defined as positive, then the inclination angle between the center line of the protruding part of the gear ring fixing part and the gear axis is negative. In the top view, the rotation angle of the helical teeth in the internal gear ring and the inclination angle of the fixing part are on opposite sides of the gear axis.

[0005] In a further optimization, the inclination angle of the fixing part is limited to the range of 25° to 35°. This angle range has been experimentally verified to provide sufficient contact area and torque transmission efficiency during helical gear meshing, while ensuring optimal balance of axial forces between the internal and external teeth. A smaller helix angle can easily lead to stress concentration at the tooth root, while an excessively large angle can cause installation difficulties; this range balances mechanical performance and manufacturing feasibility. Preferably, the inclination angle of the fixing part is exactly the same as the rotation angle of the internal helical teeth. This design ensures that the axial forces generated at both meshing points are completely equal in magnitude and opposite in direction, achieving self-balancing of axial forces through strict symmetry, eliminating the potential influence of any residual forces, and thus significantly reducing the risk of displacement under dynamic operating conditions.

[0006] In a further optimized design, the fixing part has multiple toothed protrusions evenly distributed on the outer circumference of the gear ring. These evenly distributed toothed protrusions engage with the housing grooves, increasing the contact area, enhancing torque transmission between the gear ring and the housing, and preventing deformation or breakage caused by single-point stress concentration. The toothed structure, through the engagement of the tooth tips with the grooves, provides stronger circumferential constraint, reducing the minute rotation of the gear ring during torque reversal and lowering impact noise. More preferably, the number of teeth in the fixing part is set to 40 to 50. This number of helical teeth ensures the meshing strength with the housing fixing groove while avoiding excessive tooth size that would reduce load-bearing capacity. Fewer teeth would increase inter-tooth pressure, while too many teeth would increase processing costs; this design achieves a balance between fixing reliability and economy through a compromise.

[0007] In a further optimization, considering the redundancy requirements of different application scenarios, a retaining ring can be added to the groove at the axial end of the housing for supplementary fixation. This design allows for additional axial restraint under extreme high torque or impact conditions via the retaining ring, rather than serving as the primary limiting means, thus providing flexible configuration possibilities for special applications while avoiding the problem of retaining ring material fatigue in conventional use.

[0008] Both the circumferential width of the fixing part and the circumferential width of the fixing groove have manufacturing tolerances. In the application of this invention, to facilitate smoother oblique assembly of the fixing part and the fixing groove, these manufacturing tolerances may be relatively large. This causes the side of the protruding part of the fixing part to repeatedly collide with the wall of the fixing groove during vehicle operation, generating unwanted noise. To solve the noise problem caused by the assembly gap between the fixing part and the fixing groove of the housing, the width of each tooth of the fixing part is machined to be slightly smaller than the width of the fixing groove, and elastic spring plates are provided on the outer periphery of some or all of the external teeth. During assembly, the spring plates are deformed by the gear compression, filling the gap between the gear ring and the housing, absorbing the periodic impact energy caused by changes in torque direction, effectively reducing transmission noise and improving vehicle NVH performance. More preferably, the spring plates adopt a U-shaped structure and are fitted onto the fixing part, with their opening direction facing away from the fixing groove of the housing. This design allows the spring plates to be subjected to bidirectional pressure from the teeth and the groove wall during installation, forming stable elastic deformation, ensuring that they are not easily dislodged under long-term vibration, and the opening direction design prevents them from flipping back due to compression and causing failure. The spring plates are distributed at uniform intervals, covering a portion of the outer tooth circumference. By selectively arranging the spring plate areas, material costs and processing difficulties can be reduced, while ensuring a balanced distribution of buffering force between the gear ring and the housing, avoiding additional stress concentration caused by local elasticity differences.

[0009] In a further optimized design, the gear ring body is made of aluminum alloy. Only the internal teeth undergo targeted heat treatment to improve surface hardness and wear resistance, while the outer circumferential fixed portion is not heat-treated separately. That is, when heat-treating the gear ring, the processing parameters are configured based on the requirements of the internal teeth. The lightweight properties of aluminum alloy reduce the overall weight of the reducer, while selective heat treatment ensures the meshing performance of the internal teeth while avoiding deformation of the internal teeth caused by heat treatment of the fixed portion. Since the internal teeth have higher requirements for tooth profile and surface hardness, the heat treatment processing parameters are set only to consider the needs of the internal teeth, thus balancing functional optimization and process efficiency.

[0010] Based on the above-described reducer design, the technical problem of this invention can also be solved by a vehicle that, when equipped with a planetary gear reducer featuring the aforementioned characteristics, can achieve stable and reliable transmission under conditions without snap ring constraints. This is particularly suitable for electric vehicles or off-road vehicles operating under high loads and frequent torque switching. The overall operating efficiency and service life of the vehicle's power system are significantly improved due to the reduced reducer failure rate and maintenance requirements. Attached Figure Description

[0011] The present invention will now be described in more detail with reference to the accompanying drawings, but this does not limit the overall concept of the invention.

[0012] Figure 1 A partial schematic diagram and a partial enlarged view of a planetary gear reducer designed according to the prior art are shown;

[0013] Figure 2 A perspective view of the gear ring of a planetary gear reducer designed according to the prior art is shown;

[0014] Figure 3 A perspective view of the gear ring of the planetary gear reducer designed according to this utility model is shown;

[0015] Figure 4 A partial exploded view of the planetary gear device designed according to this utility model is shown.

[0016] In this utility model, unless otherwise specified, "axial", "radial" and "circumferential" are all relative to the main gear of the planetary gear assembly. Detailed Implementation

[0017] Figure 1 A partial perspective view of a planetary gear reducer designed according to the prior art is shown. The parts related to the improvement of this utility model are the planetary gear reducer housing 100 and the gear ring 200 of the planetary gear assembly. The gear ring 200 is as follows... Figure 2As shown, it has a fixed part 201 and an internal gear part 202. In planetary gear systems, if torque is transmitted between gears via spur teeth, there will be problems such as low overlap and poor operational balance, resulting in high noise in the planetary reducer. Therefore, helical teeth are usually used to transmit torque in planetary gear systems, that is, the ring gear and the planetary gears are connected to resist torsion through helical teeth. Therefore, the internal gear part 202 of the ring gear 200 is usually designed as helical teeth. The ring gear 200 is connected to the housing of the planetary gear system 100 through the fixed part 201, thereby fixing the planetary gear system to the housing 100. Figure 2 As shown, the fixing part 201 of the gear ring 200 is designed as a straight tooth. The radially inner side of the housing 100 has a corresponding fixing groove 101. The fixing part 201 of the gear ring 200 is inserted into the fixing groove 101, thereby fixing the gear ring 200 and thus the planetary gear assembly. Because the internal teeth 202 of the gear ring 200 are designed as helical teeth, the torque transmission between the helical teeth will generate axial force during the operation of the planetary gear assembly. This may cause the gear ring 200 to shift axially, potentially leading to the gear ring 200 dislodging from the assembly. To avoid this risk, a retaining ring 300 is provided on the housing 100 in the axial direction of the gear ring 200 to further fix the gear ring 200 axially and prevent it from dislodging. However, adding the retaining ring 300 increases manufacturing costs, and in high-speed operating environments, high axial forces will be generated, and the retaining ring may also dislodge.

[0018] Figure 3 and Figure 4 An improved version according to the present invention is shown. Figure 3 A perspective view of the improved gear ring 2 is shown. The gear ring 2 also has a fixing part 21 and an internal gear part 22. The internal gear part 22 and... Figure 2 The existing technology shown is identical and unchanged; the main improvement lies in the fixing part 21. According to this invention, the fixing part 21 is designed as a helical tooth, and the direction of its rotation angle is exactly opposite to the direction of the rotation angle of the internal tooth part 22, thereby counteracting the axial force generated by the internal tooth part 22 during torque transmission. Preferably, the rotation angle of the fixing part 21 is equal in magnitude and opposite in direction to the rotation angle of the internal tooth part 22, thus effectively canceling each other out. The rotation angle of the fixing part 21 is at least not less than the rotation angle of the internal tooth part 22, and the preferred value range is between 25° and 35°. Since the gear ring is usually made of aluminum alloy, which has relatively low rigidity, in order to securely fix it to the fixing groove 11 of the housing 1 (e.g., Figure 4 As shown, the number of teeth in the fixing part 21 is preferably set between 40 and 50. If the number of teeth is too small, the fixing requirements cannot be met; however, if the number of teeth is too large, the fixing strength will also be affected because each tooth is too small.

[0019] Figure 4A partial exploded view of the planetary gear device designed according to this utility model is shown. As shown, the gear ring 2 is inserted into the fixing groove 11 of the housing 1 via the fixing part 21, thereby fixing the planetary gear device to the housing 1. During vehicle operation, the gear ring 2 can be subjected to repeated torque reversals, such as during "reversing" or "forward". There is a circumferential gap between the fixing part 21 on the gear ring 2 and the fixing groove 11 in the housing. Due to the repeated torque reversals of the gear ring 2, the fixing part 21 will repeatedly impact the fixing groove 11, which will generate undesirable noise. Changing the fixing part 21 from straight teeth to helical teeth can improve this technical problem to some extent. If you want to further improve this problem, you can consider adding spring plates to all or part of the teeth of the fixing part 21. For example, some or all of the teeth of the fixing part 21 can be machined to be smaller than the fixing groove, and then spring plates can be provided on the outer ring of the outer part 21. Due to the elasticity of the spring plates, the assembly of the gear ring 2 and the housing 1 becomes easier. During operation, the spring sheet absorbs the kinetic energy generated by the repeated impact between the toothed ring 2 and the housing 1, thereby reducing noise and improving the vehicle's NVH performance.

[0020] Obviously, the above embodiments of this utility model are merely examples for clearly illustrating the present utility model, and are not intended to limit the implementation of the present utility model. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this utility model should be included within the protection scope of the claims of this utility model.

[0021] List of reference numerals

[0022] 1. 100 Casing

[0023] 11, 101 Fixing Slot

[0024] 300 clasp parts

[0025] 2. 200 gear ring

[0026] 21, 201 Fixing Part

[0027] 22, 202 Internal teeth

Claims

1. A planetary gear reducer for a vehicle, comprising a housing (1) and a planetary gear assembly, the housing (1) having a retaining groove (11) for fixing the planetary gear assembly, the planetary gear assembly having a ring gear (2) and planetary gears, the ring gear (2) having internal teeth (22) meshing with the planetary gears and a retaining portion (21) for rotatably fixing the planetary gear assembly, wherein, The internal gear (22) is designed as a helical tooth, and the fixing part (21) has a protrusion that is inserted into the fixing groove (11). The central axis of the protrusion has an inclination angle relative to the axis of the planetary gear device, and the inclination angle is opposite to the rotation angle of the internal gear (22).

2. The planetary gear reducer according to claim 1, characterized in that, The fixing part (21) has a plurality of toothed protrusions evenly distributed on the outer circumference of the toothed ring (2).

3. The planetary gear reducer according to claim 2, characterized in that, The fixing part (21) has 40 to 50 teeth.

4. The planetary gear reducer according to claim 1, characterized in that, The tilt angle of the fixing part (21) is between 25° and 35°.

5. The planetary gear reducer according to claim 1, characterized in that, The tilt angle of the fixed part (21) is equal to the rotation angle of the internal tooth part (22).

6. The planetary gear reducer according to any one of claims 1 to 5, characterized in that, The housing (1) has a groove at its axial end, and a retaining ring is fixed in the groove.

7. The planetary gear reducer according to any one of claims 1 to 5, characterized in that, The circumferential width of the protrusion is smaller than the circumferential width of the fixing groove (11), and a spring sheet is provided on the outer periphery of all or part of the fixing part (21).

8. The planetary gear reducer according to claim 7, characterized in that, The spring sheet is U-shaped and sleeved on the protrusion, with the opening of the spring sheet facing away from the fixing groove (11).

9. The planetary gear reducer according to any one of claims 1 to 5, characterized in that, The gear ring (2) is made of aluminum alloy material, wherein the heat treatment processing parameters are set according to the requirements of the inner teeth (22) of the gear ring (2).

10. A vehicle having a planetary gear reducer according to any one of claims 1 to 9.

Images