Disconnectable Brush Module for Slip Ring Wear Reduction
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Solution Overview
Problem
Existing electric machines with externally excited synchronous rotors experience frictional losses and wear due to constant contact between brushes and slip rings, leading to high operational costs, especially in applications like battery-operated four-wheel-drive vehicles where the rotor is only temporarily energized.
Innovation Solution
A brush module with a shaft journal that can be reversibly mechanically coupled to the rotor shaft, allowing axial decoupling of brushes from the slip rings, enabling electrical energization through the shaft journal, which is synchronized with mechanical coupling and decoupling, reducing wear and friction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If brushes are constantly pressed against slip rings to ensure good electrical contacting, then electrical connectivity is improved, but brush wear and frictional losses increase continuously
Solution Approach 1:
The brush holder is made dynamically controllable, allowing it to be positioned in different radial positions relative to the rotor shaft. This enables the system to switch between contact and separation states, making the brush-slip ring interaction dynamic rather than static. The control unit receives signals and adjusts the brush holder position accordingly, implementing dynamic adaptation to operational requirements.
Solution Approach 2:
The system implements periodic contact and separation of brushes from slip rings based on operational requirements. During boost operation, brushes are positioned to contact slip rings for electrical energization. During non-boost periods, brushes are separated to eliminate unnecessary wear. This periodic action pattern matches the intermittent nature of boost axle operation.
2Reliability
If brushes are constantly pressed against rotating slip rings, then continuous electrical contact is maintained, but frictional losses occur continuously even when not needed
Solution Approach 1:
The brush holder positioning system is made dynamically controllable based on operational signals. The control unit adjusts the radial position of the brush holder to match the operational state, creating a dynamic system that adapts to minimize energy losses while maintaining reliability when needed.
Solution Approach 2:
The system changes the spatial parameter (radial position) of the brush holder to control the contact state. By varying this parameter between contact and separation positions, the system optimizes the balance between maintaining electrical contact and minimizing frictional energy losses.
3Reliability
If expensive conductive materials are used in brushes for good electrical contacting, then electrical conductivity is improved, but material cost increases
Solution Approach 1:
The system implements periodic contact where brushes only engage with slip rings during actual boost operation rather than continuously. This reduces the cumulative wear and material consumption, making the use of expensive conductive materials more economically viable by limiting their exposure to frictional wear to only when electrically conductive contact is actually required.
Solution Approach 2:
The invention converts the potential harm of continuous wear into a benefit by strategically limiting contact to only when necessary. The controlled separation during non-operational periods transforms what would be continuous material degradation into selective, minimized wear, extending brush life and reducing replacement costs.
4Adaptability or versatility
If a mechanical coupling system is added to enable reversible coupling of shaft journal to rotor shaft, then controlled energization is improved, but device complexity increases
Solution Approach 1:
The brush holder assembly is designed with multi-functionality, serving both as the electrical contact component and as the mechanically coupled element to the rotor shaft. The shaft journal is integrated into the brush holder structure, combining electrical function and mechanical coupling function in a single integrated component, thereby reducing overall system complexity.
Solution Approach 2:
The invention merges the brush holder, brushes, and shaft journal into an integrated assembly that can be reversibly coupled to the rotor shaft. This consolidation of components reduces the number of separate parts and simplifies the mechanical coupling system while maintaining the capability for controlled energization.
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 solution minimizes wear and friction, reduces operational costs, and enhances efficiency by ensuring brushes are only in contact during energization, thus extending the lifespan of the brushes and improving the machine's performance.
Implementation Method 1
The brushes are pressed by springs against the slip contacts of the rotor
Implementation Method 2
the brushes usually contain a material with large electrical conductivity (such as copper, silver or gold)
Implementation Method 3
frictional losses and wear of the brushes occur constantly at the contact sites of the slip rings
Data Source
AI summary
An electric machine comprising a rotor having a rotor shaft and a brush module having a brush holder with at least one brush for energizing the rotor, wherein the brush module comprises a shaft journal which can be coupled reversibly mechanically to the rotor shaft of the electric machine and against which the brush lies.