Bicycle Gearshift Chain Guide Non-Linear Displacement
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Solution Overview
Problem
Existing bicycle gearshifts face challenges in achieving high precision, particularly when dealing with cogsets that have a large number of sprockets, as the distance between the chain guide and sprockets is minimized only at the largest and smallest sprockets, leading to reduced precision at intermediate sprockets due to the conical shape of the cogset.
Innovation Solution
A bicycle gearshift with an articulated quadrilateral linkage and a transmission system featuring a variable gear ratio between the pin and rotary body, allowing for non-linear displacement of the chain guide, ensuring it remains close to the cogset across all sprockets, including intermediate sizes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the chain guide is positioned close to the largest sprocket to maximize sensitivity, then control sensitivity is improved, but the distance to intermediate sprockets increases reducing precision
Solution Approach 1:
The base body is made rotatable relative to the frame around the pin body axis, allowing the angular position to dynamically adjust according to the primary displacement of the chain guide. This dynamic adjustment enables the chain guide to maintain optimal proximity to different sized sprockets during gearshifting operations
Solution Approach 2:
The system changes the angular position parameter of the base body relative to the frame based on the displacement of the chain guide. This parameter change allows adaptation to different sprocket sizes, maintaining high precision control across the entire range of the cogset
2Measurement precision
If the chain guide is positioned close to intermediate sprockets, then gearshifting precision is improved, but the chain guide cannot be close to both largest and smallest sprockets simultaneously
Solution Approach 1:
The rotatable base body enables the system to dynamically adapt its configuration based on which sprocket is currently engaged. As the chain guide moves to engage different sized sprockets, the base body rotates to optimize the angular position, ensuring high precision control for each specific sprocket size
Solution Approach 2:
The mechanism provides universal adaptability to handle all sprocket sizes in the cogset uniformly. The combination of linear displacement and rotational adjustment allows the same mechanism to achieve optimal positioning whether engaging the largest, smallest, or any intermediate sprocket
Data Source
AI summary
A bicycle gearshift is operated by imposing on the chain guide a primary displacement in the axial direction with respect to a cogset, to move the chain between the sprockets. Simultaneously with imposing on the primary displacement imposing on the chain guide a secondary displacement in the radial direction with respect to the cogset. The secondary displacement is of a greater size when the primary displacement takes place in the area of the cogset with the larger sprockets whereas it is of a smaller size when the primary displacement takes place in the area of the cogset with the smaller sprockets.