Segmented Earthing Brush Mounting Plate for Small Radial Space Motors
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Solution Overview
Problem
Existing earthing brush assemblies for electric motors are not adaptable to variations in shaft and housing diameters, particularly in motors with small radial spaces between the housing and rotary shaft, leading to inadequate electrical discharge management and potential damage to rolling bearings.
Innovation Solution
An earthing brush assembly featuring a conductive brush with a unique mounting plate design, including radially and axially extending tongues and segments, allows for easy adaptation to different diameters and provides secure radial and axial retention, ensuring effective electrical potential equalization between the shaft and housing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional earthing brush assembly with annular flange and multiple tongues is used, then the brush can be retained axially and radially, but the assembly is not suitable for electric motors with small radial space between housing and shaft
Solution Approach 1:
The mounting plate is segmented into three separate mounting segments distributed circumferentially around the main body, each segment independently surrounding the brush support. This segmentation allows the assembly to adapt to different radial spaces while maintaining secure retention of the earthing brush.
2Reliability
If earthing brushes are produced for each shape and size of shaft and housing, then adequate electrical discharge management is achieved, but manufacturing complexity and cost increase
Solution Approach 1:
The mounting plate with its main body and three circumferentially distributed mounting segments forms a universal assembly that can accommodate different shaft and housing diameters. The segments can be positioned at different radial distances, allowing the same basic design to serve multiple motor sizes and configurations without requiring completely different brush assemblies for each application.
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 effectively dissipates electrical charges across varying motor sizes, reducing electrical discharges and noise while maintaining structural integrity, even in motors with limited radial space, thus protecting the rolling bearings and improving motor performance.
Implementation Method 1
By virtue of the conductivity of the fibers, the brush is kept at the same electrical potential as the housing of the electric motor. The inner and outer races of the rolling bearing are also at the same electrical potential, which reduces or even eliminates problematic electrical discharges through the rolling bearing.
Data Source
AI summary
An earthing brush assembly including an earthing brush and a brush mounting plate configured to radially and axially retain the brush, the brush having a support and a plurality of conductive individual fibres mounted in the support, the mounting plate providing a radial main body axially delimited by a first front face and by a second front face, and a plurality of tongues for axially and radially retaining the brush, the tongues being circumferentially distributed around the main body of the mounting plate and extending axially from the second front face of the main body. The brush mounting plate includes at least three mounting segments extending radially outwards from an outer surface of the main body, the mounting segments being distributed circumferentially around the main body of the mounting plate, each one of the segments locally surrounding the support of the earthing brush while remaining radially separated from the support.