Conductive Seal Assembly for RF Interference in EV Transmissions
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Solution Overview
Problem
Hybrid and electric vehicles with permanent magnet motors generate radiofrequency (RF) energy that causes interference with communication devices due to its propagation through the transmission system, leading to undesirable interference with devices like AM radios.
Innovation Solution
A conductive seal assembly is implemented around the transmission output shaft, comprising a sealing member, support member, and contact member with electrically-conductive surfaces that couple the shaft to the housing, creating a conductive path to ground and channeling RF energy away from the transmission system, thereby preventing its propagation throughout the vehicle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a traditional non-conductive seal is used, then the seal structure is simple and manufacturing is easy, but RF energy propagates through the transmission system causing interference with communication devices
Solution Approach 1:
The seal assembly combines multiple materials with different properties: a sealing member (elastomer or polymer) for sealing, support members (metal or plastic) for structural support, and conductive surfaces (metal coatings or conductive materials) for RF shielding. This composite structure simultaneously achieves sealing, structural integrity, and RF energy blocking without requiring a completely redesigned complex system
Solution Approach 2:
The seal assembly performs multiple functions simultaneously: sealing the interface between transmission components, providing structural support, and blocking RF energy propagation. By integrating these functions into a single multi-component assembly, the invention reduces the need for separate RF shielding components, thereby managing complexity while solving the interference problem
2Object-affected harmful factors
If an electrically-conductive seal assembly is implemented, then RF energy is blocked and directed to ground, but the manufacturing process becomes more complex
Solution Approach 1:
The seal assembly is divided into separate functional components: sealing members for sealing, support members for structure, and conductive surfaces for RF blocking. This segmentation allows each component to be manufactured using optimized processes for its specific function, then assembled together, simplifying the overall manufacturing approach compared to creating a single complex integrated component
Solution Approach 2:
The conductive surfaces act as intermediary elements between the non-conductive sealing members and the grounded transmission housing. These conductive layers or coatings provide the necessary electrical connection for RF shielding while allowing the sealing members to maintain their sealing function, enabling a modular manufacturing approach where conductive elements can be applied or attached to sealing components
3Reliability
If multiple components are used in the seal assembly, then RF energy is effectively blocked, but the assembly complexity increases
Solution Approach 1:
The invention merges the sealing function and RF shielding function into a single integrated seal assembly. The conductive surfaces are combined with the sealing members and support members to create a unified structure that simultaneously provides sealing and RF blocking, reducing the need for separate shielding components and simplifying the overall assembly
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 conductive seal assembly effectively inhibits RF energy from interfering with communication devices by directing it to a grounded location, reducing interference and maintaining the integrity of the transmission system by preventing fluid leakage and contaminant entry.
Implementation Method 1
an electrically-conductive surface overlying at least a portion of the contact member and at least a portion of the support member, the electrically-conductive surface contacting the transmission output shaft and the transmission output shaft housing
Data Source
AI summary
A seal for a vehicle having a transmission output shaft and a transmission output shaft housing is provided. The seal comprises a contact member at least partially surrounding and contacting the transmission output shaft, a support member coupled to the contact member, the support member at least partially surrounding the transmission output shaft and extending along the transmission output shaft, the support member coupled to the transmission output shaft housing, and an electrically-conductive surface overlying at least a portion of the contact member and at least a portion of the support member, the electrically-conductive surface contacting the transmission output shaft and the transmission output shaft housing.