Selector Shaft Gear Shift Mechanism With Fewer Parts
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Solution Overview
Problem
Existing gear-changing devices for mobility devices, such as electric-assist bicycles, are complex and costly due to their numerous parts, complicating manufacture and assembly.
Innovation Solution
A simplified gear-changing device with a selector shaft, shuttle, worm gear, and pawls, utilizing a ball piston mechanism for gear selection, reducing the number of components and simplifying assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional gear-changing device with multiple components (geared gearbox, sliding shuttle, ratchet system, balls, springs) is used, then the gear-changing functionality is achieved, but the device complexity and manufacturing cost increase
Solution Approach 1:
The patent combines multiple separate components (shuttle, ratchet system, balls, springs) into an integrated gear selection mechanism. The selector shaft directly engages with gear clusters through simplified interaction, merging functions that were previously distributed across multiple independent parts, thereby reducing overall device complexity while maintaining gear-changing functionality
Solution Approach 2:
The selector shaft serves multiple functions simultaneously: it acts as the moving element for gear selection, incorporates the engagement mechanism through its interaction with gear clusters, and provides the structural framework for the entire gear-changing system. This multi-functionality eliminates the need for separate dedicated components for each function
2Reliability
If a traditional gear-changing device with many components is used, then the gear-changing functionality is achieved, but the ease of manufacture and assembly deteriorates
Solution Approach 1:
By merging the shuttle, ratchet system, and engagement elements into a unified selector shaft mechanism, the patent reduces the number of discrete parts that need to be manufactured and assembled. Fewer components mean fewer manufacturing steps, less inventory management, and simpler assembly procedures while preserving the essential gear-changing function
3Reliability
If a traditional gear-changing device with numerous components is used, then the gear-changing functionality is achieved, but the manufacturing cost increases
Solution Approach 1:
The integration of multiple functions into the selector shaft reduces the total component count, which directly lowers manufacturing costs through reduced material usage, simplified production processes, and decreased assembly labor. The patent achieves cost reduction by eliminating redundant parts while maintaining the core gear-selection capability
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 simplified design reduces manufacturing complexity and costs while maintaining effective gear-changing functionality.
Implementation Method 1
a gear-change actuator arranged to move the shuttle along the worm gear between at least two positions
Implementation Method 2
a worm gear are arranged, a gear-change actuator arranged to move the shuttle along the worm gear
Implementation Method 3
at least two pawls arranged on the selector shaft ensuring the function of engaging the selected gear
Data Source
Figure 1~2
Figure 3a~3b
Figure 4~5
AI summary
The invention relates to a gear change device for a mobility device comprising: - a selection shaft in which are disposed a shuttle (41) and a means of moving the shuttle (41), - a gear change actuator arranged to move the shuttle (41) along the means of moving, between at least two positions, and engage a selected gear, the shuttle (41) comprising at least two means (411, 412) of selecting a gear.