Brush Cage Widened Opening for Spring Arm Blockage Prevention
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Solution Overview
Problem
In motor vehicle starters, the helical spring used to apply force to the brushes can become transversely positioned due to torque and vibrations, causing blockages in its displacement and disrupting contact with the commutator segments.
Innovation Solution
The brush cage design features a widened opening in its lateral wall to accommodate the spring arm, allowing for greater freedom of movement and preventing blockages, with specific edge inclinations and portions facilitating the insertion and centering of the spring arm and braid, and enhancing the cage's rigidity through fin connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a helical spring is used to apply force to the brush, then the brush maintains contact with the commutator segments, but the spring can become transversely positioned due to torque and vibrations causing blockages in its displacement
Solution Approach 1:
The opening in the lateral wall is designed with a widened shape that provides additional spatial dimension for the spring arm to move freely. The opening extends in the axial direction of the rotor shaft, creating a three-dimensional space that accommodates transverse positioning of the spring while preventing blockages. This dimensional approach allows the spring to maintain contact reliability without restricting its displacement freedom.
2Ease of operation
If the opening in the lateral wall is widened to allow spring freedom of movement, then blockages are prevented, but the structural rigidity of the brush cage may be compromised
Solution Approach 1:
The opening is strategically positioned and shaped in specific regions of the lateral wall where it is least likely to compromise overall structural integrity. The widened portion is localized to the area needed for spring arm passage, while the rest of the cage structure maintains its rigidity. This local modification approach allows the opening to provide spring displacement freedom without significantly weakening the cage.
3Ease of operation
If the opening shape is modified to prevent spring blockages, then displacement freedom is improved, but manufacturing complexity increases
Solution Approach 1:
The opening is designed as a simple geometric shape with straight edges and corners that can be easily fabricated using standard manufacturing processes. The opening is segmented into distinct portions: a first portion with a first edge, a second portion with a second edge, and optionally a third portion with a third edge. Each portion can be independently formed, simplifying the manufacturing process while still achieving the widened shape needed to prevent spring blockages.
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 design ensures uninterrupted displacement of the spring arm, maintaining consistent contact with the commutator segments and preventing blockages, thereby ensuring reliable operation of the motor vehicle starter.
Implementation Method 1
An elastic means, such as a spring, exerts a force on each brush held in a cage in the direction of the commutator to ensure contact between the brush and the commutator segments.
Data Source
AI summary
The invention relates mainly to a brush cage (13) for a brush holder (10) of an electric motor comprising:—two lateral walls (26) and a connecting wall (28) connecting the two lateral walls (26),—in which cage at least one of the lateral walls (26) has an opening (43) for the passage of a spring arm,—the lateral wall (26) comprising the opening (43) having a length (L0) measured between a first end (51) intended to be furthest from a commutator and a second end (52) intended to be closest to the commutator, wherein the opening (43) comprises at least a first portion (431) between the two ends (51, 52) which widens out towards the second end (52).