Derailleur Pulley Assembly Biasing Force Optimization
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Solution Overview
Problem
Existing human-powered vehicle derailleurs fail to maintain an optimal rotational force state for the pulley assembly relative to the movable member, leading to inefficiencies in shifting and propulsion.
Innovation Solution
A human-powered vehicle derailleur is designed with a pulley assembly biasing member that adjusts the rotational force by varying the pulley distance and biasing return force, ensuring the return value is within specific ranges (136 to 750) to maintain an optimal state, and includes a motor and wireless communication for enhanced functionality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the pulley assembly biasing member is designed to adjust rotational force by varying pulley distance and biasing return force, then the shifting performance and propulsion efficiency are improved, but the device complexity increases due to additional components and adjustment mechanisms
Solution Approach 1:
The patent applies parameter changes by adjusting the pulley distance between the first and second pulleys, and modifying the biasing return force of the pulley assembly biasing member to achieve optimal rotational force. This allows the system to maintain preferred shifting performance and propulsion efficiency without adding complex mechanical structures, simply by tuning existing parameters within specified ranges.
2Loss of energy
If the return value (biasing return force × pulley distance) is maintained within 136-750 to optimize rotational force, then the driving loss is reduced, but the manufacturing precision requirements increase to ensure accurate parameter control
Solution Approach 1:
The patent defines specific parameter ranges (return value between 136-750, pulley distance between 4.55-15 cm, biasing return force between 30-50 newtons) to minimize driving loss. These parameter specifications provide clear manufacturing targets that balance precision requirements with energy efficiency, allowing manufacturers to achieve optimal performance through controlled parameter variations.
3Ease of operation
If the pulley distance is increased to reduce rotational force, then the shifting smoothness is improved, but the device size increases which affects compactness
Solution Approach 1:
The patent optimizes the pulley distance within a specific range (4.55-15 cm, preferably 7-14 cm) to achieve smooth shifting operation while maintaining compact device dimensions. This parameter optimization allows the system to balance shifting quality with size constraints, avoiding both excessive force and oversized configuration.
4Productivity
If the biasing return force is increased to improve chain tension, then the propulsion efficiency is enhanced, but the ease of operation deteriorates due to increased resistance during shifting
Solution Approach 1:
The patent specifies the biasing return force within the range of 30-50 newtons to achieve optimal chain tension and propulsion efficiency while maintaining acceptable ease of operation. This parameter range balances the competing requirements of propulsion performance and shifting effort, preventing both insufficient tension and excessive resistance.
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 derailleur effectively sets the rotational force of the pulley assembly in a preferred state, optimizing shifting performance, reducing driving loss, and enhancing propulsion efficiency while allowing for compact design and wireless communication.
Implementation Method 1
a pulley assembly biasing member configured to bias the pulley assembly with respect to the movable member in the first pivotal direction
Data Source
AI summary
A derailleur comprises a base member configured to be attached to a human-powered vehicle frame, a movable member movable with respect to the base member, a pulley assembly pivotally attached to the movable member in a first pivotal direction and a second pivotal direction opposite to the first pivotal direction and including a first pulley having a first pulley axis and a second pulley having a second pulley axis, a pulley assembly biasing member configured to bias the pulley assembly with respect to the movable member in the first pivotal direction, a pulley distance (centimeter) being defined between the first pulley axis and the second pulley axis, a biasing return force (newton) being defined by rotational force of the pulley assembly relative to the movable member, and a return value defined by the biasing return force multiplied by the pulley distance. The return value is 136 or larger.