Bicycle Transmission Layout for Lower Planetary Gear Load
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Solution Overview
Problem
Existing bicycle transmissions face challenges in being durable, mechanically efficient, lightweight, and cost-effective, particularly when handling high torque loads from electric propulsion motors, and they often struggle with efficient gear shifting under load.
Innovation Solution
A bicycle transmission design incorporating a parallel transmission stage between offset axes, a planetary transmission with a clutch mechanism, and optionally a continuously variable transmission, which minimizes mechanical loads on the planetary transmission and allows gear shifting under load, using a clutch mechanism to selectively engage rotational members to a stationary part for various transmission ratios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the planetary transmission is placed before the parallel transmission in the torque path, then the planetary transmission must handle high torque loads from the electric motor, but this increases mechanical stress and reduces durability
Solution Approach 1:
The patent inverts the conventional transmission arrangement by placing the parallel transmission before the planetary transmission in the torque path. This reversal ensures that the planetary transmission receives pre-reduced torque from the parallel transmission stage, significantly lowering mechanical stress and improving durability without sacrificing transmission functionality.
2Weight of moving object
If the transmission components are arranged in a compact configuration, then the overall size and weight are reduced, but the clutch mechanism becomes difficult to access for gear shifting
Solution Approach 1:
The patent offsets the second axis from the first axis, creating a three-dimensional arrangement that allows the clutch mechanism to be positioned in a more accessible location. This dimensional adjustment enables easier access for gear shifting operations while maintaining a compact overall transmission configuration and minimizing weight.
3Power
If multiple transmission stages are combined in series, then the transmission can handle high torque loads efficiently, but the device complexity increases
Solution Approach 1:
The patent combines a parallel transmission stage and a planetary transmission stage in series to create a compact multi-stage transmission system. This merging of different transmission mechanisms allows efficient torque handling through progressive reduction while maintaining a space-efficient design suitable for bicycle applications.
Data Source
AI summary
The disclosure relates to a bicycle transmission, comprising a transmission input and a transmission output, each associated with a first axis, and a second axis offset from the first axis. The bicycle transmission comprises a parallel transmission providing a parallel transmission stage between a parallel transmission input associated with the first axis and a parallel transmission output associated with the second axis. The bicycle transmission further comprises a planetary transmission associated with the second axis.