Electric Hub Width Reduction via Nested Bearing Support
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Solution Overview
Problem
Conventional electric hub devices are difficult to design with a reduced width, which limits their compactness and efficiency in electric bicycles.
Innovation Solution
The electric hub device incorporates a support member with a recess to house a bearing member, allowing the hub body to be rotatably supported while reducing its width, and includes a deceleration mechanism with a sun gear, annular gear, and planetary gears to efficiently transmit power from the motor to the wheel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the hub body is designed to accommodate the motor and deceleration mechanism with conventional bearing arrangements, then the motor can rotate the hub body effectively, but the width of the hub body becomes large and cannot be reduced
Solution Approach 1:
The bearing member is nested within the recess of the support member, with the outer ring of the bearing member fitting into the recess and the inner ring fitting onto the hub shaft. This nested arrangement allows the bearing to be housed within the existing structural space rather than requiring additional external space, thereby reducing the overall width of the hub body while maintaining reliable rotational support functionality
Solution Approach 2:
The support member includes a recess that receives the bearing member in the width direction, effectively utilizing the depth dimension (axial direction) to accommodate the bearing rather than expanding in the width direction. This dimensional redistribution allows the hub body width to be reduced while preserving the rotational support function through proper spatial arrangement of components
2Volume of moving object
If the hub body width is reduced to enhance compactness, then the overall size and weight decrease, but the structural complexity increases due to the recess and nested bearing member configuration
Solution Approach 1:
The support member serves multiple functions: it provides structural support for the hub body, contains the recess to house the bearing member, and facilitates the nested arrangement that reduces width. By integrating these functions into a single component rather than using separate elements, the design achieves width reduction without proportionally increasing the number of parts or overall structural complexity
3Volume of moving object
If the bearing member is fit into the recess of the support member, then the width of the hub body is reduced, but the manufacturing precision requirements increase for proper fitting and alignment
Solution Approach 1:
The design specifies particular dimensional parameters for the recess and bearing member outer ring to enable proper fitting. By carefully controlling the size and tolerance parameters of these components, the nested arrangement achieves the width reduction goal while maintaining feasible manufacturing precision requirements through optimized dimensional relationships between parts
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
This configuration results in a smaller and lighter electric hub device that effectively reduces the hub body's width, enhancing the compactness and efficiency of the electric bicycle by minimizing size and weight while maintaining power transmission capabilities.
Implementation Method 1
the support member includes a bearing member fit into the recess of the support member, the bearing member rotatably receiving the hub body
Implementation Method 2
the deceleration mechanism includes a sun gear formed on the rotating shaft, an annular gear provided in the hub body, and rotatable planetary gears engaged with the sun gear and the annular gear
Data Source
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AI summary
A hub shaft 25 is inserted into a through hole 40 formed on a hub body 26, and a rotating shaft 35 of a motor 27 operates with the hub body 26 in an interlocked manner via a deceleration mechanism 45. The deceleration mechanism 45 includes a sun gear 46 formed on the rotating shaft 35, an annular gear 47 provided in the hub body 26, and planetary gears 48 engaged with the sun gear 46 and the annular gear 47. A support member 50 supporting the planetary gears 48 is provided on the motor 27 and includes a recess 54 opposed to the through hole 40 in the direction of an axis 28 of the hub shaft 25. A bearing member 59 is fit into the recess 54 of the support member 50, the bearing member 59 rotatably receiving the hub body 26.