Bicycle Hub Axial Freewheel Mechanism with Roller Bearing Preload
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Solution Overview
Problem
Existing hubs for human-powered vehicles, particularly bicycles, face challenges with freewheel mechanisms that are either too heavy, prone to wear, or require increased weight to enhance durability, leading to inefficiencies and maintenance issues due to axial displacement and potential gear shifts during freewheeling.
Innovation Solution
A hub design featuring a freewheel device with two interacting components, each having axial engagement elements that can move between freewheel and engaged positions, supported by roller bearings and a separate, stiffer freewheel component made of heavier materials, allowing for improved rigidity and easier maintenance while maintaining a lightweight structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the hub shell and rotor are supported by roller bearings, then the hub achieves smooth rotation and reduced friction, but the axial positioning and rigidity become insufficient under high loads
Solution Approach 1:
The patent introduces axial play compensation elements (spring elements or elastomeric elements) as intermediaries between the roller bearings and the hub components. These elements mediate the force transmission while compensating for axial play, thus maintaining both low friction and high positioning stability simultaneously.
Solution Approach 2:
The patent changes the physical parameters of the bearing support system by introducing preloaded spring elements that actively adjust the axial positioning under varying load conditions. This dynamic parameter adjustment allows the system to maintain optimal friction characteristics while ensuring stable axial positioning during high-load operations.
2Strength
If heavier materials or greater wall thicknesses are used to make the hub stiffer, then the hub durability and rigidity are improved, but the hub weight increases
Solution Approach 1:
The patent employs composite construction by combining lightweight hub shell materials with strategically placed reinforcement elements and preloaded bearing supports. This composite approach achieves high rigidity and durability without uniformly increasing the entire hub's weight, as the reinforcement is concentrated only where structurally necessary.
Solution Approach 2:
The patent segments the hub structure into functional zones: lightweight sections for general coverage and reinforced sections with preloaded bearings and compensation elements for high-stress areas. This segmentation allows the hub to achieve high rigidity where needed while maintaining low weight in non-critical areas.
3Stability of the object's composition
If axial displacement of the rotor is prevented, then gear shift during freewheeling is avoided, but the freewheel mechanism complexity increases
Solution Approach 1:
The patent merges the axial positioning function with the existing roller bearing support system by integrating preloaded spring elements into the bearing assembly. This combination achieves rotor axial fixation and gear position stability without adding separate complex positioning mechanisms, thus avoiding significant increases in overall mechanism complexity.
4Speed
If the number of pawls in the freewheel mechanism is increased, then the re-engagement speed when starting is improved, but the device complexity and space requirement increase
Solution Approach 1:
The patent replaces the traditional multi-pawl radial freewheel mechanism with an axial freewheel mechanism using helical gears and spring-loaded engagement elements. This substitution achieves fast re-engagement through the inherent mechanics of helical gear meshing while reducing the number of discrete pawl components and simplifying the overall mechanism structure.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The design enhances the hub's rigidity and durability, reduces wear, and simplifies assembly and disassembly, while maintaining a lightweight and compact form, thus addressing the limitations of prior art by providing a more reliable and efficient freewheel mechanism.
Implementation Method 1
a hub for at least partially human-powered vehicles and in particular bicycles, the hub comprising a hub shell which is rotatably mounted relative to a hub axle with two roller bearings arranged on opposite end regions of the hub shell
Implementation Method 2
A freewheel device is provided between the rotor and the hub shell with two interacting freewheel components, namely a freewheel component on the hub side and a freewheel component on the rotor side
Implementation Method 3
The two freewheel components can be moved in the axial direction relative to one another at least between a freewheel position and an engaged position that engages one another, with drive torque being transferrable from the rotor to the hub shell in the engaged position
Data Source
AI summary
The hub (1) for bicycles (100) comprises a hub housing (2) rotatably mounted relative to a hub axle (5), a rotor (8) rotatably mounted relative to the hub axle (2) by means of two rotor bearings (6, 7), and a freewheel assembly (9) with two interacting freewheel components (10, 20), namely a hub-side freewheel component (10) and a rotor-side freewheel component (20). The two freewheel components (10, 20) each have axial engagement elements (33) and are movable in the axial direction (30) relative to each other between a freewheel position and an engaging position (31). In the engagement position (31), a drive torque can be transmitted. The hub-side freewheel component (10) has an axial body section (13) equipped with a thread (10c) and is screwed into the hub housing (2) with a thread (2c).The hub-side freewheel component (10) includes a tool contour (70) which can be coupled with a suitably designed tool (80) to loosen the screw connection of the hub-side freewheel component (10) to the hub housing (2).