Bicycle Front Derailleur Actuation Device with Dynamic Indexing
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Solution Overview
Problem
Existing front derailleur actuation devices for bicycles have a significant distance between chain guide plates, which compromises quicker and more precise upward gearshifting while still allowing the use of all toothed wheels, especially when the chain is on the largest crown gear.
Innovation Solution
An actuation device with a rotating member and a stationary member featuring a fastening track with stop areas and an additional stop area outside the track, allowing the cable-winding bush to reach intermediate and maximum positions for precise gearshifting without compromising the use of all toothed wheels, by using a pointer that slides on the fastening track and an alternative arc path during gear operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the distance between chain guide plates is reduced for quicker gearshifting, then the speed and precision of upward gearshifting is improved, but the ability to use all toothed wheels (especially with largest crown gear) is compromised
Solution Approach 1:
The patent introduces a dynamic indexing mechanism where the cable-winding bush can be held in multiple predetermined angular positions through interaction between the indexing bush and ball-carrying disc. This dynamic positioning system allows the system to adapt between two operational modes: reduced distance for speed and full distance for compatibility, resolving the contradiction by making the distance adjustable rather than fixed
Solution Approach 2:
The patent changes the parameter of distance between chain guide plates from a fixed value to a variable parameter with at least two distinct values. The indexing mechanism enables switching between a first distance (reduced for speed) and a second distance (increased for compatibility), allowing the system to optimize performance based on operational requirements
2Adaptability or versatility
If the distance between chain guide plates is increased to maintain compatibility with all toothed wheels, then the versatility is improved, but the speed and precision of upward gearshifting deteriorates
Solution Approach 1:
The indexing mechanism provides dynamic control over the cable-winding bush position, enabling the system to switch between extended distance mode (for compatibility) and reduced distance mode (for speed). This resolves the contradiction by making the distance adjustable rather than permanently fixed at the larger value
Solution Approach 2:
The patent segments the indexing mechanism into distinct functional components: the cable-winding bush, the indexing bush with multiple stop areas, and the ball-carrying disc with corresponding balls. This segmentation allows independent optimization of each component's function while maintaining the overall ability to provide both distance configurations
3Manufacturing precision
If multiple stop areas are added to the indexing bush for precise positioning, then the manufacturing precision is improved, but the device complexity increases
Solution Approach 1:
The indexing mechanism is designed to be self-regulating through the interaction between the ball-carrying disc and indexing bush. The balls automatically engage with the stop areas to maintain precise angular positions without requiring external control systems or complex actuation mechanisms, achieving precision through self-service
Solution Approach 2:
The ball-carrying disc acts as an intermediary element between the cable-winding bush and the indexing bush. It transfers and maintains the angular positioning information through the balls that engage with the stop areas, simplifying the overall mechanism while achieving precise positioning through this mediating component
Data Source
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AI summary
The invention relates to an actuation device (10) of the control cable of a front derailleur (300) of a bicycle, comprising a casing (11), configured for fixing to bicycle handlebars, a cable-winding bush (13) mounted in the casing (11) angularly rotatable about a rotation axis (X) in a first angular direction (A) between a first angular position and a last angular position and in a second angular direction (B) between the last angular position and the first angular position to actuate a front derailleur (300) of a bicycle, a rotating member (14) mounted in the casing in a rotatable manner about the rotation axis (X) and a stationary member (18) mounted in a non-rotatable manner in the casing (11), wherein one from the rotating member (14) and the stationary member (18) is provided with at least one pointer (15, 16) slidably engaged on a fastening track (19) equipped with a plurality of stop areas (20) provided on the other member (18). The stationary member (18) or the rotating member (14) provided with said fastening track (19) further comprises at least one further stop area (24) not arranged along said fastening track (19), said further stop area (24) being engageable by said pointer (15, 16) and being arranged between two successive stop areas (20) of said fastening track (19), the cable-winding bush (13) passing between two angular positions following the passage of the pointer (15, 16) between two stop areas (20).