Axial Brush Assembly With Bypass Path for Slip Ring Reliability
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Solution Overview
Problem
Existing electric motor designs face challenges in maintaining reliable electrical connections between the rotor shaft and the slip rings, leading to issues such as increased electrical resistance, wear, and potential for bearing current-induced damage.
Innovation Solution
The design incorporates a rotor assembly with conical projections or convex receptacles on brushes and slip rings, biased by springs, and includes internal conduits and bearing current bypass brushes to ensure stable electrical connections and grounding, minimizing resistance and wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional brush and slip ring connection is used, then the structure is simple, but electrical connectivity and reliability are insufficient due to bearing current bypass and varying internal resistance
Solution Approach 1:
The brush assembly is segmented into multiple functional components: axial brush for primary electrical connection, bearing current bypass brush for circulating current management, and spring elements for maintaining contact pressure. This segmentation allows each component to perform its specific function optimally, improving overall electrical connectivity and reliability while managing the complexity through modular design
Solution Approach 2:
The patent introduces a bearing current bypass brush as an intermediary component that provides a dedicated path for circulating currents to flow through the bearing assembly without affecting the primary electrical connection. This intermediary element resolves the contradiction by handling the harmful bearing currents separately, thereby improving reliability without requiring complete redesign of the main brush assembly
2Reliability
If conventional brush and slip ring connection is used, then the manufacturing is simple, but bearing current bypass issues occur leading to component wear
Solution Approach 1:
The brush assembly is divided into distinct functional segments including axial brushes, bearing current bypass brushes, and spring elements. Each segment can be manufactured and assembled independently, which improves component durability through specialized design while managing manufacturing complexity through modular assembly procedures
Solution Approach 2:
The bearing current bypass brush acts as an intermediary that protects the main brush and slip ring interface from harmful circulating currents. This mediator component extends component life by preventing electrochemical wear on critical surfaces while adding a relatively simple manufacturing step of installing an additional brush element
3Loss of energy
If conventional electrical connection is used, then the device complexity is low, but electrical losses increase due to varying internal resistance
Solution Approach 1:
The electrical connection path is segmented into multiple parallel paths through the use of axial brushes and bearing current bypass brushes. This segmentation creates multiple current flow routes that reduce the overall internal resistance and minimize electrical losses, while the modular structure manages the increased complexity through systematic arrangement of parallel connection elements
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 enhances the reliability and efficiency of electrical connections, reduces friction and wear, and mitigates bearing current-induced damage, thereby improving the performance and longevity of the electric motor.
Implementation Method 1
The first brush is biased towards the first slip ring with a first spring element
Data Source
AI summary
A rotor assembly includes a rotor shaft and a rotor core supported by the rotor shaft and surrounded by a plurality of windings. The rotor assembly also includes a first brush engaging a first slip ring fixed relative to a first distal end of the rotor shaft. The first brush includes one of a first conical projection or a first convex receptacle and the first slip ring includes the other of the first conical projection or the first convex receptacle. A first electrical connection extends between the first slip ring and the plurality of windings. A second brush is configured to engage a second slip ring with the second slip ring fixed relative to the rotor shaft. A second electrical connection extending between the second slip ring and the plurality of windings.