Electric Motor Brush System Retention Design
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Solution Overview
Problem
The assembly of electric motors with commutator-based brush systems is complex and costly due to the need for additional components like retaining rings and specialized tools, and there is a risk of brush damage during assembly and operation from collisions with the commutator.
Innovation Solution
A brush system with a brush made from pressed carbon dust and a flexible stranded connection line, where a spring element is connected to the brush, guiding it in a quiver-like brush shaft with a longitudinal slot that includes a constriction to prevent collision with the commutator during assembly, allowing for secure and cost-effective assembly and operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If brushes are mounted in the brush holder without additional retaining components, then device complexity is reduced, but manufacturing precision deteriorates due to the need for complex brush grooves and retaining contours
Solution Approach 1:
The patent merges the brush retention function with the brush holder structure itself by integrating a retaining protrusion directly into the brush holder body. This eliminates the need for separate retaining rings or complex brush grooves, thereby reducing device complexity while maintaining manufacturing precision through a unified structural design.
Solution Approach 2:
The brush holder is designed to perform multiple functions: guiding the brush, providing electrical insulation, and retaining the brush in place through an integrated retaining protrusion. This multi-functional design eliminates the need for additional specialized components, reducing overall device complexity while maintaining precise brush positioning.
2Reliability
If retaining rings are used to hold brushes in place, then brush retention is improved, but assembly time increases due to additional installation and removal steps
Solution Approach 1:
The retaining function is merged into the brush holder structure through an integrated retaining protrusion, eliminating the need for separate retaining rings. This allows brushes to be retained reliably while significantly reducing assembly and disassembly time, as no additional components need to be installed or removed.
Solution Approach 2:
The brush holder structure itself provides the retention function through its integrated protrusion design, making the system self-sufficient. The brush is retained by the structural geometry of the holder rather than requiring external retaining components, streamlining the assembly process.
3Reliability
If brushes are pressed inwards against spring force during motor mounting, then brush contact with commutator is ensured, but brush damage risk increases due to collision with commutator
Solution Approach 1:
The brush holder is designed with a retaining protrusion that pre-positions the brush in a retracted state before motor assembly. This preliminary positioning prevents the brush from protruding too far forward, eliminating the risk of collision with the commutator during assembly while ensuring proper contact is established afterward.
Solution Approach 2:
The integrated retaining structure provides a built-in mechanical stop that prevents excessive brush protrusion before assembly issues can occur. This design feature acts as a preventive measure, cushioning against the potential harmful effect of brush-commutator collision during motor mounting.
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 solution simplifies the assembly process, reduces production costs, and prevents brush damage by ensuring the brush does not collide with the commutator, enabling a secure and efficient electrical connection while compensating for operational abrasion.
Implementation Method 1
a spring element which, in its operative connection with the brush, exerts a spring force on the brush to cause it to rest against the commutator
Implementation Method 2
allowing them to slide under the force of the springs, thus enabling automatic brush adjustment
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
The invention relates to a brush system (20) of an electric motor (8), comprising a commutator (24), at least one brush (26) that is guided within a brush duct (28) and is provided with a connection line (32), and a spring element (30, 38, 40, 46, 50) that exerts a spring force on the brush (26) when the spring element is effectively connected thereto, such that the brush (26) rests against the commutator (24); the brush duct (28) includes a longitudinal duct slot (56) inside which the connection line (32) extends and which has a constriction (58) that the connection line (32) penetrates when the effective connection between the spring element (30) and the brush (26) is established.