Bevel Planetary Hub Transmission with Roller Teeth
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Solution Overview
Problem
Current bicycle hub transmissions suffer from high internal friction, limited torque capacity, incompatibility with direct-drive and mono-blade mounting configurations, and a lack of adaptability to emerging bicycle designs.
Innovation Solution
The integration of bevel planetary gears with roller teeth allows for larger planet gears, reducing friction and increasing torque capacity, while enabling compatibility with both chain-drive and direct-drive systems and mono-blade mounting through a configuration that axially separates driven and driving elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If conventional planetary gears with small teeth are used in a compact hub assembly, then the hub transmission achieves a compact design, but internal friction increases significantly
Solution Approach 1:
The patent transitions from conventional spur gears to bevel gears, changing the gear orientation from parallel to perpendicular axes. This dimensional change allows the planet gears to engage the ring gear at an angle, enabling larger planet gear dimensions while maintaining the same compact hub volume, thereby reducing internal friction without increasing overall size.
Solution Approach 2:
The patent changes the gear tooth parameters by using bevel gears with larger pitch diameters and different tooth geometry compared to conventional spur gears. This parameter change allows for larger contact surfaces and reduced pressure, decreasing internal friction while maintaining compact dimensions through optimized gear arrangement.
2Volume of moving object
If small gear teeth are used in the planetary hub, then the hub transmission remains compact, but torque capacity is limited
Solution Approach 1:
By using bevel gears with perpendicular axis engagement, the patent enables larger planet gear dimensions within the same compact hub volume. The conical gear geometry allows for increased tooth surface area and better load distribution, significantly enhancing torque capacity without increasing the overall hub transmission size.
3Adaptability or versatility
If conventional hub gear configuration is used, then chain-drive compatibility is achieved, but direct-drive compatibility is lost
Solution Approach 1:
The patent designs the hub transmission with bevel planetary gears that can operate effectively in both chain-drive and direct-drive configurations. The perpendicular gear engagement and modular component design allow the same hub to accommodate different drive systems, making it universally compatible without requiring configuration changes or increasing device complexity.
4Adaptability or versatility
If conventional hub design is used, then double-blade mounting compatibility is maintained, but mono-blade mounting capability is lost
Solution Approach 1:
The patent creates a hub transmission design that can be mounted on both conventional double-blade axles and modern mono-blade forks. The symmetric bevel gear arrangement and flexible mounting interface allow the same hub to adapt to different fork configurations, providing universal mounting compatibility without increasing device complexity.
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
This solution significantly reduces internal friction, enhances torque capacity, and facilitates compatibility with various mounting configurations, making bicycle hub transmissions more efficient and versatile.
Implementation Method 1
The integration of bevel planetary gears with roller teeth allows for larger planet gears, reducing friction
Data Source
AI summary
Compared to derailleur bicycle chain transmissions, internal hub transmissions for bicycles have higher friction and a lower torque capacity. In addition, bicycle hub transmissions are generally incompatible with alternate drive arrangements such as direct-drive, or different mounting options such as mono-blade mounting. The present invention addresses these concerns by employing bevel gears with roller teeth in a planetary bicycle hub transmission. The bevel gear configuration allows larger planet gears, which gives sufficient circumferential space for roller teeth to reduce the meshing friction. The larger planet gears also increase the allowable torque. Furthermore, the bevel gear configuration facilitates the high ratios required for direct-drive, and results a hub structure highly compatible with mono-blade mounting. With this is view, the hub is designed for both chain-drive and direct-drive, and for both double-blade and mono-blade mounting.