Electric Bicycle Driving Unit Axial Size Reduction
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Solution Overview
Problem
Existing electric assist bicycle driving units are hindered by the large size due to the conventional placement of circuit boards distant from the motor and gear reducer, making it difficult to minimize the axial dimensions of the unit.
Innovation Solution
A driving unit design featuring a substrate positioned between the motor and driven gear, with a transmission shaft and gears arranged to reduce size, including a substrate with a mounting surface perpendicular to the crankshaft axis, and a housing configuration that allows for efficient space utilization and heat dissipation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the circuit board is positioned distant from the motor and gear reducer, then the circuit board can be easily mounted and accessed, but the axial size of the driving unit increases
Solution Approach 1:
The circuit board is repositioned from a distant location to a position between the motor and driven gear, utilizing the radial space within the driving unit. This dimensional reorganization allows the circuit board to be mounted closer to the motor while maintaining accessibility, thereby reducing the axial length without compromising ease of operation.
2Temperature
If the circuit board is positioned distant from the motor, then heat dissipation is easier, but the overall size of the driving unit increases
Solution Approach 1:
The circuit board mounting position is merged with the space between the motor and driven gear, combining the functions of heat dissipation and compact sizing. This integrated positioning allows the circuit board to benefit from proximity to the motor for heat management while contributing to the reduced overall volume of the driving unit.
Data Source
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AI summary
A driving unit for use in an electric assist bicycle with reduced size as measured in an axial direction of the crankshaft is provided. A driving unit 50 may be used in an electric assist bicycle 10. The driving unit 50 includes a motor 60, a first transmission gear 84 and a driven gear 104. Out of the motor 60, first transmission gear 84 and driven gear 104, a first component 104 is a component with the largest diameter as viewed in an axial direction of the crankshaft 54, and a second component 60 is a component with the second largest diameter. A substrate 150 is located between the first and second components 104 and 60 as measured in an axial direction of the crankshaft 54.