EMI Shield Member for Electric Machine Enclosure
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Solution Overview
Problem
High voltage electric machines produce significant electro-magnetic interference (EMI) that can interfere with other electronic devices and must comply with federal regulations limiting EMI emissions, requiring effective methods to confine EMI within the machine while maintaining a sealed enclosure.
Innovation Solution
An EMI blocking member with an insulating layer and an electrically conductive EMI shield member is positioned across the opening of the enclosure, grounded to the housing to prevent EMI escape, allowing a non-conductive cover and ensuring compliance with EMI emission limits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a gasket formed from an electrically conductive material is positioned between the enclosure and the cover to ensure all portions of the housing remain electrically grounded, then EMI emissions are confined to the interior portion, but the enclosure cannot remain sealed
Solution Approach 1:
The EMI blocking function is segmented from the sealing function. The EMI shield member with insulating layer provides EMI blocking, while a separate gasket member provides sealing. This segmentation allows each component to perform its primary function without compromise - the EMI shield blocks emissions without needing to be conductive throughout, and the gasket provides seal integrity without EMI blocking requirements.
Solution Approach 2:
The insulating layer acts as an intermediary between the EMI shield member and the gasket member. It allows the EMI shield to be electrically isolated from the cover while still maintaining the EMI blocking function, and enables the gasket to provide sealing without requiring electrical conductivity. This intermediary resolves the conflict between EMI blocking and sealing requirements.
2Object-affected harmful factors
If the housing and cover are connected to an electrical ground to confine EMI emissions, then EMI is blocked, but the complexity of the grounding system increases
Solution Approach 1:
The EMI blocking function is extracted from the grounding system. Instead of relying on a complex grounding network involving conductive gaskets and multiple ground paths, the invention uses an EMI shield member with insulating layer that provides EMI blocking through its inherent shielding properties. This extraction simplifies the grounding system while maintaining EMI confinement effectiveness.
3Adaptability or versatility
If an EMI shield member with insulating layer is used to block EMI emissions, then non-conductive materials can be used for the cover, but additional components are required
Solution Approach 1:
The EMI shield member with insulating layer and the gasket member are merged into a single integrated EMI blocking member assembly. This integration reduces the number of separate components that would otherwise be required - the insulating layer is incorporated directly into the EMI shield structure, and the gasket is positioned within the same assembly, simplifying the overall component count while enabling non-conductive cover materials.
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 effectively blocks EMI emissions from the electric machine, allowing the use of non-conductive materials for the cover and maintaining electrical grounding, thus ensuring compliance with regulatory limits and preventing interference with other devices.
Implementation Method 1
The EMI shield member is configured and disposed to block EMI release from the housing via the enclosure
Implementation Method 2
The grounding member establishes an electrical ground between the EMI shield member and the housing
Data Source
AI summary
A method of blocking electro-magnetic interference (EMI) in an electric machine having a housing including an interior portion, an opening leading to the interior portion, and an enclosure positioned about the opening, includes positioning an EMI blocking member in the enclosure across the opening. The EMI blocking member includes an insulating layer having a first surface and a second surface. An EMI shield member is positioned on one of the first and second surfaces. The EMI shield member includes a surface formed from an electrically conductive material that substantially covers the one of the first and second surfaces. The EMI shield member is grounded to the housing. The EMI shield member is configured and disposed to block EMI release from the housing via the enclosure.