Electric Bicycle Motor Unit With Stator-Coupled Heat Dissipation
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Solution Overview
Problem
Existing motor units for electric bicycles lack effective heat dissipation capabilities, leading to potential performance issues and increased weight due to excessive resin usage.
Innovation Solution
A motor unit design featuring a metallic cup in pressure contact with the stator to efficiently transfer and dissipate heat, reducing the need for extensive resin molding and minimizing weight while enhancing cooling efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If resin molding technique is used to house the motor, then the motor unit structure is simplified and manufacturing is easier, but the heat dissipation capability is insufficient
Solution Approach 1:
The invention uses a composite structure combining resin and metal materials. The motor case is resin-molded for ease of manufacture and structural integration, while a metallic cup is inserted into the resin case to provide efficient heat dissipation. This composite approach allows the motor unit to benefit from both the manufacturing advantages of resin molding and the thermal conductivity of metal materials.
2Strength
If extensive resin molding is used to house the motor, then the motor is well protected and structured, but the overall weight of the motor unit increases
Solution Approach 1:
The invention extracts the heat dissipation function from the resin motor case and assigns it to a separate metallic cup component. This allows the resin case to be minimized to only the extent necessary for structural support and protection, while the metal cup provides the required thermal management. The extraction of excessive resin material reduces overall weight while maintaining essential protective functions.
3Temperature
If a metallic cup is introduced for heat dissipation, then heat dissipation capability is improved, but the device complexity increases
Solution Approach 1:
The invention merges the metallic cup with the resin motor case through insertion and fixing, creating an integrated hybrid structure. The metallic cup is fitted into the resin case and secured in place, combining the thermal management function of metal with the structural and manufacturing advantages of resin molding. This merging approach adds heat dissipation capability while minimizing the increase in overall device complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The design improves heat dissipation and reduces the overall weight of the motor unit, addressing the limitations of existing technologies by directly transferring heat from the stator to the metallic cup for efficient dissipation.
Implementation Method 1
An inner peripheral surface of the metallic cup is in pressure contact with the stator... directly transferring heat from the stator to the metallic cup for efficient dissipation
Data Source
AI summary
A motor unit for use in electric bicycles, the motor unit comprising: a motor having a rotary shaft; a unit case to house the rotary shaft partially; an input shaft arranged in the unit case to penetrate through the unit case and to be rotatable around an axis; an input body configured to rotate along with the input shaft; an output body configured to rotate around the axis upon receiving rotational force of the input body; and a control board housed in the unit case and configured to control rotation of the motor. The unit case includes: a first heat dissipating portion connected to a first surface of the control board; and a second heat dissipating portion connected to a second surface opposite from the first surface of the control board.