Brush Holder Fixation via Bridge Portions and Fitting Grooves
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Solution Overview
Problem
The existing brush holding device for DC motors faces challenges in achieving sufficient strength due to limitations in the height and thickness of engaging pieces, which affects the solid fixation of the brush holder, particularly in compact and lightweight designs like starter motors.
Innovation Solution
The brush holding device incorporates a holder plate with a center hole and elongated holes, featuring bridge portions that insert into fitting grooves on the brush holder's thick-wall portion, allowing for a secure fixation and distributing the load to enhance strength while facilitating assembly without excessive force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the thickness of the holder plate is increased to provide sufficient bending strength for engaging pieces, then the fixation strength is improved, but the weight and axial length of the DC motor increase
Solution Approach 1:
The holder plate is segmented into multiple functional regions: engaging pieces for electrical connection, bridge portions for mechanical fixation, and reinforcing ribs for structural support. This segmentation allows each region to be optimized independently, enabling sufficient fixation strength without increasing the overall plate thickness and motor weight.
Solution Approach 2:
Instead of increasing thickness in the axial direction, the invention utilizes the radial and lateral dimensions by extending bridge portions laterally and adding reinforcing ribs. This dimensional redistribution provides structural strength without increasing the motor's axial length.
2Strength
If the height of engaging pieces is increased to improve fixation solidity, then the bending strength is improved, but the axial length of the DC motor increases
Solution Approach 1:
The fixation function is segmented between engaging pieces (for electrical connection) and bridge portions (for mechanical anchoring). This allows the engaging pieces to maintain compact height while the bridge portions extend laterally to provide sufficient fixation solidity without increasing axial length.
3Strength
If the thickness of the holder plate is increased to allow larger gap height for engaging pieces, then the plate-like convex parts can have sufficient thickness, but the device complexity and weight increase
Solution Approach 1:
The holder plate is divided into functional segments including engaging pieces, bridge portions, and reinforcing ribs. This segmentation allows the plate-like convex parts to achieve sufficient thickness through localized reinforcement rather than increasing the overall plate thickness, thereby reducing device complexity.
4Strength
If the bridge portions are made rigid to provide strong fixation force, then the fixation strength is improved, but the insertion force required during assembly becomes excessive
Solution Approach 1:
The bridge portions are designed with optimized dimensional parameters including width, length, and thickness ratios. These parameter adjustments create a balance where the bridge portions provide sufficient fixation force while maintaining flexibility during insertion, reducing the required assembly force.
Solution Approach 2:
The bridge portions exhibit dynamic characteristics during assembly, transitioning from a flexible state during insertion to a rigid state during operation. This allows easy assembly followed by strong fixation, resolving the contradiction between insertion ease and fixation strength.
Data Source
AI summary
The brush holding device includes a brush holder having a brush-housing chamber, and a holder plate to which the brush holder is attached. The holder plate is formed with a center hole at a center portion thereof, the center hole having a size allowing a commutator to path therethrough, and a pair of elongated holes opposing to each other with respect to the opening portion, the elongated holes defining bridge portions with the opening hole. The brush holder has a thick-wall portion integral with a bottom wall of the brush-housing chamber, the thick-wall portion being formed with fitting grooves at lateral sides thereof. The bridge portions are inserted into the fitting grooves so that the brush holder is fitted to the holding plate in such a state that the thick-wall portion is caught between the bridge portions.