Bicycle Drive Unit Single Housing Axial Alignment
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Solution Overview
Problem
Current drive units for electric power-assisted bicycles face inefficiencies in power transmission and increased noise and vibration due to axial misalignment between components, which complicates the design and reduces performance.
Innovation Solution
The drive unit design incorporates a single cylindrical housing to support both the first speed reducer and power transmission, reducing axial misalignment, and utilizes a bell-and-spigot-joint structure and thrust washers to minimize friction and improve mechanical efficiency, along with a planetary gear mechanism and bevel gears to optimize power transmission and reduce size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple housings are used to support the first speed reducer and power transmission separately, then each component can be independently supported, but axial misalignment occurs between components and power transmission efficiency decreases
Solution Approach 1:
The patent combines multiple separate housings into a single integrated housing structure that supports both the first speed reducer and power transmission components. This merging eliminates the interfaces between multiple housings, preventing axial misalignment and improving power transmission efficiency while reducing overall structural complexity.
2Reliability
If axial misalignment is allowed in the design, then manufacturing and assembly are easier, but power transmission efficiency decreases and noise and vibration increase
Solution Approach 1:
The single housing structure is designed with pre-integrated mounting positions and support features for both the first speed reducer and power transmission components. This preliminary integration ensures precise axial alignment is built into the structure from manufacturing, eliminating the need for complex post-assembly alignment adjustments while maintaining high power transmission efficiency.
3Stability of the object's composition
If additional housings and fastening devices are used to support components, then structural stability is improved, but the bicycle frame design flexibility is reduced
Solution Approach 1:
By merging multiple housings into a single integrated housing unit, the patent reduces the number of external fastening devices and mounting points required on the bicycle frame. This consolidated structure maintains structural stability through internal component integration while providing a cleaner, more flexible mounting interface that enhances bicycle frame design flexibility.
Data Source
AI summary
A drive unit for a bicycle includes a housing, a first speed reducer including an input shaft and an output shaft coaxial with each other to reduce rotation transmitted from an electric motor, a power transmission to which rotation of the output shaft of the first speed reducer is transmitted, and a second speed reducer to change a direction of an axis of rotation transmitted from the power transmission. The housing includes a single cylindrical first housing to support the first speed reducer and the power transmission without any housing other than the first housing being interposed therebetween.