Slip Ring Extension for Electric Machine Cooling
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Solution Overview
Problem
Existing electric machines with slip rings face limited heat dissipation due to the insulating material used in slip ring carriers, which restricts the flow of heat from the slip rings to the cooled rotor shaft, leading to inefficient thermal management.
Innovation Solution
The extension of the slip ring beyond the lateral surface of the rotor shaft into a recess, increasing the heat dissipation area and using a coolant-conducting region within the rotor shaft to enhance cooling, with configurations such as trapezoidal, L-shaped, or T-shaped cross sections to optimize heat transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a slip ring carrier made of electrically and thermally insulating material is used to mount slip rings, then electrical insulation is ensured, but heat dissipation from the slip ring to the cooled rotor shaft is severely limited
Solution Approach 1:
The slip ring is extended in the axial direction beyond the lateral surface, utilizing the third dimension (axial direction) to increase the heat transfer surface area. This dimensional extension allows heat to be dissipated over a larger area without compromising the electrical insulation provided by the slip ring carrier.
Solution Approach 2:
The extension section of the slip ring is specifically positioned within the recess of the rotor shaft where cooling is most effective. This local optimization concentrates the heat transfer function in the region with最佳的 cooling conditions, maximizing heat dissipation efficiency while maintaining electrical insulation elsewhere.
2Temperature
If the heat dissipation area is increased to improve thermal management, then heat dissipation efficiency improves, but the device structure becomes more complex
Solution Approach 1:
The extension section of the slip ring serves dual functions: it increases the heat transfer surface area for improved cooling, and simultaneously acts as part of the electrical contact structure. This multi-functionality achieves better thermal management without adding separate cooling components, thereby avoiding increased device complexity.
Solution Approach 2:
The heat dissipation function is merged with the slip ring structure itself rather than being implemented as a separate cooling system. The extension section integrates thermal management directly into the electrical contact component, eliminating the need for additional complex cooling mechanisms.
3Area of stationary object
If the slip ring is extended beyond the lateral surface into the recess, then the heat transfer area is increased, but the space for coolant flow may be reduced
Solution Approach 1:
The extension section is positioned within the recess where cooling conditions are already optimized. This local placement ensures that the extended area operates in the region with the best thermal gradient and coolant flow characteristics, maximizing heat transfer efficiency per unit area.
Solution Approach 2:
The slip ring extension utilizes the axial dimension within the recess rather than radially expanding into the coolant flow path. This dimensional approach increases heat transfer area without significantly impeding the radial coolant flow necessary for effective cooling.
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 significantly improves heat dissipation efficiency by increasing the heat transfer area and maintaining electrical insulation between slip rings, allowing for robust and efficient thermal management without complex structures.
Implementation Method 1
The heat flow through the slip ring carrier or the rotor shaft is proportional to the product of the thermal conductivity of the material used and the area participating in the heat transport perpendicular to the heat transport direction.
Implementation Method 2
an extension section of the slip ring, which is at least partially accommodated in the recess, extends beyond the lateral surface in one or both axial directions of the rotor shaft
Data Source
AI summary
An electric machine, including a stator and a rotor shaft having a cooling device, which shaft carries at least one slip ring, which has a lateral surface, which electrically contacts a contact element fixed on the stator, and which is at least partially accommodated in a recess of the rotor shaft, wherein an extension section of the slip ring, which is at least partially accommodated in the recess, extends beyond the lateral surface in one or both axial directions of the rotor shaft.