Shaft Grounding Ring Thermal Preconditioning for Low-Impedance Contact
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Solution Overview
Problem
Existing shaft grounding rings face challenges in providing a reliable, low-impedance electrical connection between a rotating shaft and a non-rotating housing, as high preload forces increase rotational resistance and wear, while low preload forces fail to form a reliable path for high-frequency interference currents.
Innovation Solution
A shaft grounding ring with thermally preconditioned, elastically bendable plastic-based contact elements that form a sliding contact with the shaft or sleeve, ensuring constant elasticity and a low-impedance connection through thermal aging and preloading during production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a high preload force is applied to the discharge element against the shaft, then the impedance of the transition is reduced and electrical connection is improved, but the rotational resistance of the shaft increases and wear of contact elements increases
Solution Approach 1:
The discharge element is divided into multiple contact elements arranged circumferentially around the shaft. This segmentation allows the total preload force to be distributed across multiple smaller contact points, reducing the rotational resistance and wear at each individual contact point while maintaining the overall electrical connection reliability through the collective action of all contact elements.
2Reliability
If a high preload force is applied to the discharge element against the shaft, then the impedance of the transition is reduced and electrical connection is improved, but the wear of contact elements increases
Solution Approach 1:
The discharge element is segmented into multiple contact elements that share the total preload force. This distribution reduces the wear rate at each individual contact element, extending their service life while maintaining reliable electrical connection through the collective contact of all elements.
Solution Approach 2:
The contact elements are made from elastomeric material, changing the physical parameter of material hardness and elasticity. This material selection provides inherent elastic deformation capability that accommodates shaft runout and vibration, maintaining consistent electrical contact over extended service periods while reducing mechanical wear through compliant contact.
3Force
If a low preload force is applied to the discharge element, then the rotational resistance and wear are reduced, but the impedance increases and reliable return conducting path is not formed
Solution Approach 1:
Multiple contact elements distributed circumferentially provide sufficient total contact area and conductivity even with low individual preload forces. The collective electrical conductance of all contact elements together forms a reliable return conducting path while each element exerts only minimal force on the shaft, reducing rotational resistance and wear.
4Stability of the object's composition
If the elasticity of contact elements changes during operation due to thermal load, then the preloading of sliding contact becomes unstable, but thermal aging during operation cannot be controlled
Solution Approach 1:
The contact elements are subjected to thermal aging treatment during the manufacturing process before the shaft grounding ring is put into service. This preliminary thermal exposure pre-stabilizes the elastomeric material's elasticity, so that subsequent thermal loads during normal operation cause minimal additional change in elastic properties, maintaining stable sliding contact preloading throughout the service life.
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 method ensures a stable, low-impedance electrical connection with minimal thermal impact during operation, maintaining reproducible elasticity and effective interference current return paths, suitable for both dry and oil environments.
Implementation Method 1
the contact elements undergo thermal aging, and therefore a subsequent thermal load arising during the operation of the shaft grounding ring only negligibly affects the elasticity of the contact elements
Implementation Method 2
The contact elements are elastically bendable and, due to their inherent bending elasticity, bring about a preloading of the sliding contact
Implementation Method 3
the shaft grounding ring has at least one discharge element, which is made of an electrically conductive PTFE material and rests against the shaft via an elastically bent edge region with elastic deformation. As a result, an electrically conductive sliding contact is formed between the shaft and the discharge element
Data Source
AI summary
A method for producing a shaft grounding ring includes providing a shaft grounding ring having an annular main body and contact elements arranged on the main body. The contact elements are electrically conductive and plastic-based. The contact elements are configured to establish an electrically conductive sliding contact with a circumferential surface of a shaft or of a sleeve placed onto the shaft. The contact elements are elastically bendable such that the contact elements are configured to preload the electrically conductive sliding contact. Additionally, the method includes thermally preconditioning the shaft grounding ring before use.