Electric Motor Brush Holder Axial Positioning Design
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Solution Overview
Problem
Existing electric motor designs require complex positioning structures, such as abutting portions in the yoke housing, to axially position the brush holder, which complicates the motor's structure and increases manufacturing costs.
Innovation Solution
The electric motor design separates the yoke housing and gear housing, with the brush holder installed between them, using a holder member with contact portions that contact the yoke housing and a base member with engaging portions for snap-fitting, eliminating the need for internal positioning structures in the yoke housing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If an abutting portion is formed in the yoke housing to axially position the holder member, then the holder member can be positioned, but the structure of the yoke housing becomes complex
Solution Approach 1:
The positioning function is extracted from the yoke housing and transferred to the holder member itself. The holder member includes a contact portion that contacts the opening end portion of the yoke housing, eliminating the need for an abutting portion in the yoke housing. This extraction principle resolves the contradiction by maintaining positioning precision while simplifying the yoke housing structure.
Solution Approach 2:
Instead of providing a positioning structure in the stationary yoke housing, the invention inverts the approach by equipping the moving holder member with the positioning contact portion. This inversion transfers the positioning responsibility from the housing to the component being positioned, thereby simplifying the housing structure while maintaining positioning accuracy.
2Productivity
If the holder member and base member are permanently engaged, then assembly is simple, but disassembly and repair become difficult
Solution Approach 1:
The engagement between the holder member and base member is made dynamic rather than static. The snap-fit engagement allows the components to be firmly connected during operation (maintaining productivity) while enabling easy disassembly when needed (improving ease of repair). The elastic deformation capability of the engaging portions provides the necessary dynamic characteristic.
Solution Approach 2:
The snap-fit engagement mechanism allows for temporary discarding of the engaged state during repair, with the ability to recover the engagement after repair. The holder member can be easily separated from the base member for brush replacement, then re-engaged to restore the original state, combining assembly simplicity with repair ease.
3Ease of operation
If the holder member is axially spaced from the base member by an axial gap, then the contact portion can contact the yoke housing, but the holder member requires additional positioning mechanisms
Solution Approach 1:
The holder member is designed with multi-functionality: it simultaneously provides brush holding, electrical contact, and axial positioning functions. The contact portion serves both as an electrical contact element and as a positioning element that defines the axial position relative to the yoke housing, eliminating the need for separate positioning mechanisms.
Solution Approach 2:
The invention merges the positioning function with the contact function in the holder member. The contact portion that provides electrical connection also serves as the positioning reference by contacting the opening end portion of the yoke housing. This merging of functions reduces device complexity while maintaining ease of operation.
Data Source
AI summary
A brush holder is placed between a yoke housing and a gear housing and includes a holder member and a base member. The holder member is installed to an opening of the yoke housing and holds a plurality of brushes. The base member is installed to the holder member and includes a connector configured to connect with an external connector to receive an electric power. An output side end part of the yoke housing has a flange portion, through which the gear housing is fixed to the yoke housing. The holder member includes a contact portion that contacts an opening end portion of the yoke housing in an axial direction of a rotatable shaft. The contact portion is axially spaced from the base member by an axial gap.