Bicycle Drive Unit Layout for Compact Motor Integration
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Solution Overview
Problem
In bicycle drive units, it is challenging to reduce the size of the propulsion assist motor component in a direction parallel to the crankshaft's rotational axis without compromising the integrity and appearance of the system.
Innovation Solution
The bicycle drive unit is designed with a housing configuration where the propulsion assist motor's rotational axis intersects the crankshaft's axis, allowing for a reduced distance and dimensions in the parallel direction, and is accommodated within the bicycle frame to enhance space utilization and aesthetics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the rotational axis of the propulsion assist motor is made parallel to the rotational axis of the crankshaft, then the motor can be easily integrated with the crankshaft, but the size of the bicycle drive unit in the direction parallel to the crankshaft rotational axis increases
Solution Approach 1:
The patent changes the spatial relationship between the motor and crankshaft from a parallel axis configuration to an intersecting axis configuration. Specifically, the rotational axis of the propulsion assist motor intersects the rotational axis of the crankshaft, allowing the motor to be positioned in a different dimensional orientation that reduces the overall length of the drive unit in the direction parallel to the crankshaft axis while maintaining effective power transmission integration
2Shape
If the housing is made to accommodate within the frame, then the outer appearance integrity is improved and space is efficiently used, but the installation complexity increases
Solution Approach 1:
The housing is divided into multiple portions: a first portion that accommodates the crankshaft and a second portion that accommodates the propulsion assist motor. These portions are connected in a manner that allows the housing to be accommodated within the bicycle frame while maintaining structural integrity and aesthetic appearance. The segmented design enables the housing to fit into the frame's available space without compromising the overall appearance or requiring excessive installation complexity
Data Source
AI summary
A bicycle drive unit includes a housing, a crankshaft and a propulsion assist motor. The housing is configured to be mounted on a frame of a bicycle. The crankshaft is provided to the housing. The assist propulsion motor is provided to the housing to assist propulsion of a bicycle. The propulsion assist motor includes a rotational axis extending in a direction intersecting a direction in which crankshaft extends. The bicycle drive unit is configured such that a distance from a rotational axis of the crankshaft to a part of the bicycle drive unit that is the farthest from the rotational axis of the crankshaft in a direction parallel to the rotational axis of the propulsion assist motor is smaller than or equal to 210 mm.