A motorcycle reverse gear

Abstract

This utility model discloses a reverse gear for motorcycles, relating to the field of motorcycle transmission technology. The gear includes a bevel gear body with external teeth integrally arranged around its outer circumference. These external teeth have a helical bevel tooth structure, with each tooth having an equal width. A groove is formed on the end face of the body, and internal teeth with a straight tooth structure are circumferentially arranged on the inner wall of the groove, with each tooth having an equal width. An annular boss coaxial with the body is located at the center of the groove, and a through hole is located at the center of the body for mating with an output shaft. The external and internal teeth are formed by a single forging process, resulting in continuous metal flow lines and improved coaxiality and strength. The two sides of the internal teeth are arc-shaped, with a continuous arc-shaped chamfered surface at the tooth root and a symmetrical double-beveled chamfer at the tooth tip, effectively reducing stress concentration and meshing impact noise. The gear body is made of 20CrMnTi alloy, and the tooth surfaces are sequentially coated with a TiN and molybdenum disulfide composite coating to improve wear resistance, corrosion resistance, and friction reduction. This reverse gear has a compact structure, smooth transmission, low noise, and long service life, making it suitable for reverse gear systems in large-displacement motorcycles.

Description

Technical Field

[0001] This utility model relates to the field of motorcycle transmission technology, specifically to a motorcycle reverse gear. Background Technology

[0002] The reverse gear of a motorcycle is the core component for reversing a motorcycle, directly affecting the vehicle's handling, reliability, and driving comfort. As motorcycles develop towards larger displacement, higher performance, and lower noise, the existing reverse gear technology can no longer meet market demands, mainly manifested in the following ways: (1) Poor coaxiality: The external teeth of the existing gears are machined using a plywood machine, resulting in relatively poor coaxiality with the internal teeth after machining. (2) Insufficient strength: The existing gears are mostly machined using cutting (such as hobbing and gear shaping), which cuts off the metal flow lines and results in insufficient bending strength at the tooth root, making it prone to tooth root breakage under heavy loads (such as climbing and reversing fully loaded). (3) High operating noise: The existing reverse gears are straight teeth, and the impact of straight tooth meshing is large, especially when reversing at low speeds, the gear meshing frequency is superimposed with the resonance of the vehicle body, affecting the driving experience. Utility Model Content

[0003] In view of this, the purpose of this utility model is to provide a reverse gear for motorcycles to solve the above problems.

[0004] To achieve the above objectives, this utility model provides the following technical solution:

[0005] This utility model provides a reverse gear for a motorcycle, including a bevel gear body. The gear body has external teeth on the outer circumference of the tooth tip circle. The external teeth have a helical bevel tooth structure, and each tooth has an equal tooth width. The end face of the tooth tip circle of the gear body is provided with a groove. The inner wall of the groove is provided with internal teeth in the circumferential direction. The internal teeth have a straight tooth structure, and each tooth has an equal tooth width. An annular boss is provided in the groove. The central axis of the boss coincides with the central axis of the gear body. A through hole is opened at the central axis of the gear body, penetrating the gear body. The external teeth and internal teeth are forged in one piece, and the metal flow lines are continuous.

[0006] In this invention, the external teeth on the outer circumference of the gear body's tip circle are helical bevel teeth with a spatial helix shape distributed along a conical surface. During meshing, they form a progressive surface contact, resulting in better transmission smoothness and load-bearing capacity, as well as lower noise. Furthermore, in this invention, the external and internal teeth are forged in a single process, with continuous metal flow lines, which improves both coaxiality and strength.

[0007] Furthermore, the internal tooth structure has two sides that are arc-shaped surfaces that slope outward from the end furthest from the groove sidewall to the end closest to the groove sidewall.

[0008] Furthermore, the tooth root transition zone of the internal tooth is provided with a continuous arc-shaped chamfered surface. Preferably, the chamfer width is 0.1-0.15 times the module, and the chamfer angle is 30°±5°. This configuration can effectively reduce the stress concentration factor at the tooth root and improve the bending fatigue strength.

[0009] Furthermore, the tip of the internal tooth is provided with a symmetrical double-beveled chamfer, and the chamfered surface extends to the tooth end face to form a guide edge. Preferably, the chamfer height is 1 / 10 to 1 / 8 of the tooth height, and the chamfer angle is 45° ± 5°. This configuration can effectively reduce meshing impact noise.

[0010] Furthermore, the gear body is made of 20CrMnTi alloy. Using 20CrMnTi as the gear body material provides excellent surface strengthening and core toughness retention, as well as excellent machinability, making it suitable for integral forging of internal and external gears.

[0011] Furthermore, each tooth surface of the external and internal teeth is sequentially coated with a TiN coating and a molybdenum disulfide coating. Preferably, the thickness of the TiN coating 8 is 2-3 μm, and the thickness of the molybdenum disulfide coating 7 is 0.5-1 μm. Sequentially coating the external and internal tooth surfaces with TiN and molybdenum disulfide coatings utilizes the combined effect of these coatings to effectively reduce the coefficient of friction, noise, and improve the wear resistance and corrosion resistance of the gears; furthermore, it also enhances the fatigue strength of the gears.

[0012] Beneficial Effects: The motorcycle reverse gear disclosed in this utility model features an integrally forged external and internal gear teeth with continuous metal flow lines, improving coaxiality and increasing the strength of both internal and external teeth. Compared to traditional machining methods, this improves coaxiality by over 30% and increases tooth root bending fatigue strength by 25%, effectively preventing tooth root fracture during heavy-load reversing. The external teeth utilize a helical bevel gear structure, offering better transmission smoothness and load-bearing capacity, while also reducing noise. The internal teeth have symmetrical double-beveled chamfers at the tooth tip, effectively reducing meshing impact noise. A continuous arc-shaped chamfered surface in the tooth root transition zone effectively reduces the tooth root stress concentration coefficient and enhances bending fatigue strength. TiN and molybdenum disulfide coatings are sequentially sprayed onto the tooth surfaces of both the external and internal teeth. The combined effect of these coatings effectively reduces the friction coefficient, lowers noise, and improves the gear's wear and corrosion resistance. Furthermore, it enhances the gear's fatigue strength. Through this combined effect, the measured noise reduction is over 10 dB. In summary, the reverse gear provided by this utility model has excellent coaxiality and strength performance, and also has low noise. Attached Figure Description

[0013] Figure 1 This is a cross-sectional view of the reversing gear;

[0014] Figure 2 This is a schematic diagram of the overall structure of the reversing gear.

[0015] Figure 3 This is a schematic diagram of the internal tooth structure.

[0016] Figure 4 This is a schematic diagram of the coating structure.

[0017] Explanation of reference numerals in the attached drawings: 1. Gear body; 2. Groove; 3. Boss; 4. External tooth; 5. Internal tooth; 6. Through hole; 8. Titanium nitride coating; 7. Molybdenum disulfide coating; 10. Arc surface; 10. Rhomboid surface; 11. Beveled chamfer. Detailed Implementation

[0018] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0019] Example 1

[0020] like Figure 1 and Figure 2 As shown, this utility model provides a reverse gear for a motorcycle, including a bevel gear body 1. The gear body 1 has external teeth 4 on the outer circumference of the tooth tip circle. The external teeth 4 are spiral bevel teeth with equal tooth width. The end face of the tooth tip circle of the gear body 1 is provided with a groove 2. The inner wall of the groove 2 is provided with internal teeth 5 in the circumferential direction. The internal teeth 5 are straight teeth with equal tooth width. An annular boss 3 is provided in the groove 2. The central axis of the boss 3 coincides with the central axis of the gear body 1. A through hole 6 is opened at the central axis of the gear body 1, penetrating the gear body. The external teeth 4 and internal teeth 5 are forged in one piece, and the metal flow lines are continuous.

[0021] In this invention, the external teeth on the outer circumference of the addendum circle of the gear body 1 are helical bevel teeth with a spatial helix shape distributed along a conical surface. During meshing, they form a progressive surface contact, resulting in better transmission smoothness and load-bearing capacity, as well as lower noise. In this invention, the external teeth 4 and internal teeth 5 are forged in one piece, with continuous metal flow lines, which improves both coaxiality and strength.

[0022] In one embodiment, such as Figure 3 As shown, the internal tooth 5 structure has two sides that are arc surfaces 9 that slope outward from the end away from the groove sidewall to the end near the groove sidewall.

[0023] In one embodiment, such as Figure 3 As shown, the tooth root transition zone of the internal tooth 5 is provided with a continuous arc-shaped chamfered surface 10. Preferably, the width of the chamfer is 0.1-0.15 times the module, and the chamfer angle is 30°±5°. This setting can effectively reduce the stress concentration factor at the tooth root and improve the bending fatigue strength.

[0024] In one embodiment, such as Figure 3 As shown, the tooth tip of the internal tooth 5 is provided with a symmetrical double-bevel chamfer 11. Preferably, the chamfer height is 1 / 10-1 / 8 of the tooth height, the chamfer angle is 45°±5°, and the chamfer surface extends to the tooth end face to form a guide edge. This configuration can effectively reduce meshing impact noise.

[0025] In one embodiment, the gear body is made of 20CrMnTi alloy. Using 20CrMnTi as the gear body material provides excellent surface strengthening and core toughness retention, as well as excellent machinability, making it suitable for integral forging of internal and external gears.

[0026] In one embodiment, such as Figure 4 As shown, each tooth surface of the external tooth 4 and the internal tooth 5 is sequentially coated with a TiN coating 8 and a molybdenum disulfide coating 7. Preferably, the thickness of the TiN coating 8 is 2-3 μm, and the thickness of the molybdenum disulfide coating 7 is 0.5-1 μm. By sequentially coating the tooth surfaces of the external tooth 4 and the internal tooth 5 with the TiN coating 8 and the molybdenum disulfide coating 7, the combined effect of these two coatings can effectively reduce the coefficient of friction, reduce noise, and improve the wear resistance and corrosion resistance of the gears; furthermore, it can also enhance the fatigue strength of the gears.

[0027] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A motorcycle reverse gear, characterized in that, The gear includes a bevel gear body. The gear body has external teeth on the outer circumference of its tooth tip circle. The external teeth are spiral bevel gears with equal tooth width. The end face of the gear body's tooth tip circle has a groove. The inner wall of the groove has internal teeth circumferentially arranged. The internal teeth are straight teeth with equal tooth width. An annular boss is provided in the groove. The central axis of the boss coincides with the central axis of the gear body. A through hole is provided at the central axis of the gear body. The external teeth and internal teeth are forged in one piece, and the metal flow lines are continuous.

2. The motorcycle reverse gear according to claim 1, characterized in that, The internal tooth structure has two sides that are arc surfaces that slope outward from the end furthest from the groove sidewall to the end closest to the groove sidewall.

3. The motorcycle reverse gear according to claim 1, characterized in that, The root transition zone of the internal teeth is provided with a continuous arc-shaped chamfered surface.

4. The motorcycle reverse gear according to claim 1, characterized in that, The inner tooth tip is provided with a symmetrical double-bevel chamfer, and the chamfer surface extends to the tooth end face to form a guide edge.

5. The motorcycle reverse gear according to claim 1, characterized in that, The gear body is made of 20CrMnTi alloy.

6. The motorcycle reverse gear according to claim 1, characterized in that, Each tooth surface of the external and internal teeth is sequentially coated with a TiN coating and a molybdenum disulfide coating.

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