Bicycle Transmission With Variable Speed Coupling
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Solution Overview
Problem
Current bicycle transmission systems lack a versatile and efficient mechanism for variable speed transmission that can be easily integrated with bicycle frames, limiting the range of gear ratios and pedaling assistance.
Innovation Solution
A bicycle transmission apparatus comprising a base member, input and output shafts, transmission members, and coupling members that allow for variable speed transmission through a combination of rotational axes and coupling mechanisms, including a one-way clutch and assist device for pedaling assistance, which can be integrated with the bicycle frame for enhanced performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a conventional bicycle transmission system is used, then the structure is simple, but the range of gear ratios is limited and pedaling assistance is insufficient
Solution Approach 1:
The transmission system is divided into multiple independent transmission members (first transmission member and second transmission member) that can rotate about different rotational axes. This segmentation allows each member to contribute differently to the overall gear ratio, expanding the range of available gear ratios while maintaining manageable system complexity through modular design.
Solution Approach 2:
The system employs a variable speed stage that can change the speed ratio between the first and second transmission members dynamically. This dynamic adjustment capability, combined with the one-way clutch mechanism, allows the transmission system to adapt to different riding conditions and terrains, providing both a wide gear ratio range and automated assistance without requiring an overly complex manual shifting system.
2Adaptability or versatility
If a variable speed transmission mechanism is added, then the gear ratio range is expanded, but the device complexity increases
Solution Approach 1:
The one-way clutch mechanism enables automatic engagement and disengagement of the variable speed stage based on the rotational direction and torque conditions. This self-service feature allows the transmission system to automatically select appropriate gear ratios without requiring complex manual control mechanisms, thereby expanding the gear ratio range while limiting the increase in operational complexity.
Solution Approach 2:
The first coupling member is designed to couple the first transmission member to the second transmission member while also serving as part of the variable speed stage mechanism. This multi-functionality reduces the number of separate components needed, allowing the system to achieve variable speed transmission with fewer dedicated coupling mechanisms, thus expanding gear ratio options while controlling overall device complexity.
3Loss of energy
If the input shaft and output shaft are spaced apart, then the transmission efficiency is improved, but the base member size increases
Solution Approach 1:
The system utilizes multiple rotational axes (input rotational axis, first rotational axis, and second rotational axis) that are spatially arranged in three-dimensional space. By spacing the input and output shafts apart along different axes rather than simply increasing linear distance, the design achieves better transmission efficiency through optimized torque transfer paths while minimizing the overall volume of the base member through efficient spatial utilization.
Data Source
AI summary
A bicycle transmission apparatus comprises a base member, an input shaft, a first transmission member, a second transmission member, and a first coupling member. The base member is configured to be attached to a bicycle frame as a separate member from the bicycle frame. The first transmission member is rotatable relative to the base member about a first rotational axis different from the input rotational axis. The second transmission member is rotatable relative to the base member about a second rotational axis different from each of the input rotational axis and the first rotational axis. The first coupling member is configured to couple the first transmission member to the second transmission member to transmit rotation of the first transmission member to the second transmission member at a variable speed stage.