Bicycle Transmission Hub Without Ring Gear
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Solution Overview
Problem
Conventional bicycle transmission hubs require a chain to drive the hub shaft and have a complex structure due to the need for a ring gear, limiting direct hub shaft rotation and efficient force transmission.
Innovation Solution
A bicycle transmission hub design featuring a hub shaft with first pawls, driving gears with ratchets, driven gears, an output wheel, and a hub shell with a ratchet, controlled by a transmission controller that includes an outer ring, inner ring, and lever mechanism to manage pawl engagement and rotation force transfer without a ring gear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a conventional planetary gear system with ring gear is used, then the hub shaft can be rotated, but the structure becomes complicated and direct hub shaft rotation is limited
Solution Approach 1:
The invention extracts and removes the ring gear from the conventional planetary gear system, retaining only the essential sun gear and planetary gears. This extraction eliminates the structural complexity and interference caused by the ring gear while preserving the core functionality of the planetary gear mechanism, enabling direct hub shaft rotation without the complicating elements of traditional internal gear systems
Solution Approach 2:
The invention inverts the conventional approach by making the planetary gear carrier the fixed element rather than the ring gear. The hub shaft is fixed and the planetary gears rotate around it, with the carrier serving as the stationary support structure. This inversion allows direct rotation force application to the hub shaft while simplifying the overall structure by eliminating the need for a ring gear
2Ease of operation
If a chain and driven sprocket are used to rotate the hub shaft, then the hub shaft can be driven, but direct driving without chain is not possible
Solution Approach 1:
The invention merges the functions of the chain drive and planetary gear system into a single integrated mechanism. The planetary gears directly engage with the fixed hub shaft, combining the force transmission function previously performed by the chain with the gear reduction function in one unified structure, eliminating the need for separate chain and sprocket components
Solution Approach 2:
The planetary gears serve as an intermediary mechanism that directly transfers rotation force from the input to the fixed hub shaft. Instead of using a chain as the intermediary, the planetary gears provide a direct mechanical connection that enables force transmission while allowing the hub shaft to be fixed, thus mediating between the input force and the stationary hub shaft
3Reliability
If ring gear, sun gear, and planetary gears are all provided, then the planetary gear system functions, but the structure becomes complicated
Solution Approach 1:
The invention extracts the ring gear from the planetary gear system, removing this component entirely while maintaining the functional integrity of the system. The sun gear and planetary gears continue to operate effectively with the fixed hub shaft serving the role previously filled by the ring gear, reducing the number of components from three (ring gear, sun gear, planetary gears) to two (sun gear, planetary gears)
Solution Approach 2:
The fixed hub shaft assumes multiple functions: it serves as the stationary support for the planetary gears, the element that receives and transmits rotation force, and the structural equivalent of the ring gear. This multi-functionality allows the system to operate reliably with fewer components, as the hub shaft compensates for the removed ring gear through its fixed position and structural role
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
Enables direct rotation of the hub shaft and efficient transfer of input rotation force to the hub shell without a ring gear, simplifying the structure and enhancing transmission efficiency.
Implementation Method 1
a ratchet formed on the inner peripheral surface thereof to receive a rotation force transferred by the second pawl
Implementation Method 2
a plurality of first pawls arranged on the outer peripheral surface thereof... a ratchet formed on the inner peripheral surface thereof to receive a rotation force transferred by the first pawls
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
A bicycle transmission hub according to the present invention comprises: a hub shaft to which a rotation force is input, the hub shaft having a plurality of first pawls arranged on the outer peripheral surface thereof; a transmission controller for controlling the first pawls to appear and disappear; a plurality of driving gears, each of which has a ratchet formed on the inner peripheral surface thereof to receive a rotation force transferred by the first pawls, the driving gears having a different number of teeth, the hub shaft extending through the center of each of the driving gears; a plurality of driven gears, which are engaged with the driving gears, respectively, have a different number of teeth, and rotate while being coupled to each other; an output wheel, which rotates while being coupled to a driving gear adjacent thereto among the driving gears and has a second pawl disposed on the outer peripheral surface thereof; and a hub shell, which has a wheel spoke connected thereto and has a ratchet formed on the inner peripheral surface thereof to receive a rotation force transferred by the second pawl.