Derailleur Rotational Force Control Structure
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Solution Overview
Problem
Existing human-powered vehicle derailleurs fail to effectively manage rotational force of the pulley assembly, leading to inefficiencies in shifting between sprockets and increased friction, which affects driving efficiency and chain tension.
Innovation Solution
A human-powered vehicle derailleur with a rotational force control structure that includes a cam member, an abutment member, and a biasing member, which applies additional forces to the pulley assembly to optimize its position and reduce rotational force, ensuring proper chain engagement and tension across different sprockets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a conventional pulley assembly biasing member is used, then the pulley assembly can be biased toward a first rotational position, but the rotational force cannot be effectively managed across different sprockets, leading to increased friction and shifting inefficiencies
Solution Approach 1:
The patent applies dynamics by making the pulley assembly rotatable about a pivot axis, allowing it to dynamically adjust its rotational position between a first rotational position (for smallest sprocket) and a second rotational position (for largest sprocket). This dynamic adjustment optimizes chain tension and reduces friction for each gear position, improving shifting efficiency while minimizing energy loss.
Solution Approach 2:
The patent changes the rotational parameter of the pulley assembly to optimize performance. By controlling the rotational position of the pulley assembly relative to the movable member, the system adjusts chain tension and friction characteristics for different sprocket engagements, thereby improving productivity while reducing energy loss.
2Productivity
If the pulley assembly is fixed in position, then the structure is simple, but chain tension cannot be optimized across different sprockets, affecting driving efficiency
Solution Approach 1:
The patent introduces dynamic capability by allowing the pulley assembly to rotate about a pivot axis, enabling it to adapt its position for optimal chain tension when engaging different sprockets. This dynamic adjustment improves driving efficiency while adding controlled complexity through the rotational mechanism.
Solution Approach 2:
The patent applies preliminary action by pre-configuring the pulley assembly with a biasing member that naturally biases it toward the first rotational position. This preliminary setup ensures optimal chain tension is automatically established when the chain engages the smallest sprocket, improving driving efficiency without requiring complex active control systems.
3Reliability
If additional forces are applied to the pulley assembly, then rotational force is optimized for each sprocket position, but the device complexity increases
Solution Approach 1:
The patent uses a biasing member to apply a preliminary force that biases the pulley assembly toward the first rotational position. This preliminary action ensures reliable chain engagement with the smallest sprocket and provides a baseline tension that improves reliability across all gear positions without requiring complex active control mechanisms.
Solution Approach 2:
The patent applies local quality by providing different cam surface geometries at different locations on the cam member. The first cam surface interacts with the abutment member when the pulley assembly is in the first pivotal position, while the second cam surface interacts when in the second pivotal position. This localized differentiation optimizes chain engagement reliability for each specific gear position.
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 enhances driving efficiency by maintaining optimal chain tension and reducing friction, thereby improving shifting performance and minimizing energy loss during operation.
Implementation Method 1
a biasing member configured to bias the abutment member
Implementation Method 2
The rotational force control structure includes a cam member having a first cam surface, an abutment member configured to abut the first cam surface
Data Source
AI summary
A derailleur comprises a base member, a movable member, a linkage structure, a pulley assembly, and a rotational force control structure configured to control rotational force of the pulley assembly relative to the movable member. The pulley assembly is pivotally movable relative to the movable member about a pivot axis in first and second directions. The pulley assembly is configured to move in the first direction upon moving from a second pivotal position toward a first pivotal position. The rotational force control structure includes a cam member having a first cam surface, an abutment member configured to abut the first cam surface, and a biasing member configured to bias the abutment member. The abutment member is configured to abut the first cam surface by the biasing member to apply first additional force to the pulley assembly in the first direction while the pulley assembly is in the first pivotal position.