Internal Derailleur Ratchet Ring Control for Smooth Gear Shifting
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Solution Overview
Problem
Existing internal derailleurs with two-layer planet gear speed change systems experience temporary gear shifts and require high torque, leading to unsmooth operation and increased manufacturing complexity.
Innovation Solution
A gear switching control device with a track sleeve and serially connected axial ratchet control rings that control the axial ratchets of each planet gear speed change system, ensuring identical speed ratios and reducing torque, simplifying the gear change process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a two-layer planet gear speed change system is used to reduce the number of speed change stages, then manufacturing cost is reduced, but temporary gear shifts occur causing unsmooth operation
Solution Approach 1:
The control device opens the axial ratchet of the second planet gear speed change system before closing the axial ratchet of the first planet gear speed change system. This preliminary action ensures that the second system is ready to engage before the first system disengages, preventing temporary gear shifts and ensuring smooth operation while maintaining the cost-effective two-layer structure
2Adaptability or versatility
If axial ratchets are controlled to switch between fixed and free rotating states, then speed change stages are achieved, but high torque is required
Solution Approach 1:
The control device prepares the second planet gear system by opening its axial ratchet before the first system closes its axial ratchet. This preliminary preparation allows for a more gradual and distributed torque requirement, as the second system is already ready to engage rather than requiring simultaneous torque from both systems
Solution Approach 2:
The control device acts as an intermediary that coordinates the switching of axial ratchets between the two planet gear speed change systems. By managing the sequence of opening and closing operations, it distributes the torque requirements over time rather than requiring peak torque from both systems simultaneously
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 solution provides a smooth gear shifting experience with reduced torque and simplified manufacturing, achieving identical speed change ratios across layers and lowering production costs.
Implementation Method 1
Each layer of the planet gear speed change system has identical speed change ratio and as a result, and thus they have same module structure... each ratchet control ring controls the axial ratchet switch of a respective planet gear speed change system
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A gear switching control device of an internal derailleur includes a plurality of planet gear speed change systems; a gear switching control unit; a plurality of axial ratchet control rings (21, 22, 23) for controlling action of a plurality of axial ratchets (17); said plurality of axial ratchets (17); and the plurality of axial ratchet control rings are serially connected by the same gear switching control unit; wherein the gear switching control unit comprises a track sleeve (2), one end of the track sleeve is installed with a force accept portion (2a) and another end thereof is installed with a linking rod (2b) which is used to serially connect the plurality of axial ratchet control rings; each of the axial ratchet control rings is formed with a respective connecting hole (21a, 22a, 23a); each axial ratchet control ring being installed with a cam or cam-like device (21b, 21c, 22b, 22c, 23b, 23c); said cams or cam-like devices each having a different operating moving range.