Bicycle Transmission with Load-Shifting Clutches for Pedaling Shifts
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Solution Overview
Problem
Existing bicycle transmission systems often require the rider to stop pedaling to shift gears, limiting the ability to up- or downshift based on pedal force or electromotor torque, and suffer from high friction losses and weight.
Innovation Solution
A transmission system comprising a continuously variable transmission (CVT) and multiple transmission ratios, with load-shifting clutches allowing gear shifting without stopping pedaling, and a control unit for electronic actuation, minimizing friction and weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If traditional derailleur or gear hub systems are used, then gear shifting mechanism is provided, but up- and downshifting is not always possible depending on rider pedal force
Solution Approach 1:
A clutch mechanism is introduced as an intermediary between the input shaft and output shaft of the transmission system. The clutch can be selectively engaged or disengaged to decouple the drivetrain, allowing gear shifts to occur without requiring the rider to stop pedaling. This mediator enables shifting under load by temporarily removing the torque transmission path during the shifting operation.
Solution Approach 2:
The patent replaces traditional mechanical derailleurs or hub-based shifting mechanisms with an electronically controlled clutch system. Instead of using complex mechanical cable-actuated derailleurs or hub internals that require torque cessation for shifting, an electronic clutch actuator controlled by a control unit enables seamless shifting while maintaining mechanical simplicity and reliability.
2Ease of operation
If rider stops pedaling to shift gears, then gear ratio change is possible, but loss of time and productivity occurs
Solution Approach 1:
The clutch mechanism enables continuous pedaling action while performing gear shifts. By decoupling the input and output shafts during shifting operations, the system maintains uninterrupted torque transmission and rider momentum, eliminating the need to stop pedaling for gear changes. This ensures continuous useful action without interruption.
3Adaptability or versatility
If multiple transmission ratios are provided, then adaptability is improved, but device complexity increases
Solution Approach 1:
The transmission system is segmented into distinct functional modules: a first transmission providing two transmission ratios, a second transmission providing two additional transmission ratios, and a clutch mechanism for selective engagement. This segmentation allows multiple gear ratios to be achieved through modular combinations rather than a single complex transmission, simplifying the overall system architecture while maintaining versatility.
Solution Approach 2:
The clutch mechanism serves multiple functions: it enables gear shifting between different transmission ratios, allows for continuous pedaling during shifts, and can be selectively engaged or disengaged based on riding conditions. This multi-functional component reduces the need for separate mechanisms for each function, thereby reducing overall device complexity while maintaining adaptability.
Data Source
AI summary
Disclosed is a transmission system for a vehicle, particularly for a bicycle. The system comprises an input and an output, and a first transmission and a second transmission between the input and the output, wherein the first transmission and the second transmission are connected in series. The first transmission is selectively operable according to a first transmission ratio or a second transmission ratio, and has a first load-shifting clutch for switching the first transmission from the first transmission ratio to the second transmission ratio and/or vice versa. The second transmission is selectively operable according to a third transmission ratio or a fourth transmission ratio, and has a second load-shifting clutch for switching the second transmission from the third transmission ratio to the fourth transmission ratio and/or vice versa.