Vehicle Subframe Grounding Through Coated Fastener Interfaces
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Solution Overview
Problem
Conventional grounding methods for electrical devices on vehicles, especially those mounted on subframes with surface coatings, are bulky and can damage the coatings, and serrated fasteners compromise corrosion resistance.
Innovation Solution
A grounding assembly that uses fasteners to create conductive pathways through non-conductive surface coatings by forming threads in weld nuts and employing Zn-Ni coated conductive elements, ensuring electrical connection without damaging the coatings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional grounding straps or brackets are used to ground the electrical device, then the electrical connection is established, but the grounding components become large in size and may damage the surface coating on the subframe
Solution Approach 1:
The grounding system is segmented into multiple small fastening points distributed across the subframe surface, replacing the conventional single large grounding strap or bracket. This segmentation allows the grounding function to be achieved through multiple small contact points that do not concentrate stress on any single location, thereby preventing surface coating damage while maintaining electrical connectivity
Solution Approach 2:
A non-conductive intermediate layer is introduced between the fastener and the subframe surface coating. This intermediary layer prevents direct mechanical contact between the fastener and the coating, eliminating the harmful effect of coating damage while still allowing the fastener to secure the grounding element to the subframe structure
2Reliability
If large grounding straps are used to span the distance between the electrical device and vehicle body, then grounding is achieved, but the device complexity and component size increase
Solution Approach 1:
The grounding system is divided into multiple small fastening points with small grounding elements distributed across the subframe, replacing the conventional single large grounding strap. This segmentation reduces the size of individual grounding components and simplifies the overall grounding system while maintaining effective electrical connection through multiple contact points
Solution Approach 2:
The grounding function is merged with the existing fastening structure. The same fasteners that secure the grounding element to the subframe also provide the electrical connection path, eliminating the need for separate large grounding straps and reducing overall component complexity
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
Provides effective grounding without the need for large straps or brackets, maintaining corrosion resistance and electrical conductivity, while avoiding damage to surface coatings.
Implementation Method 1
The first fastener is configured to provide an electrically conductive pathway between the electrical device and the subframe through the first fastener
Implementation Method 2
The subframe and the electrical device may be electrically isolated at the surface interface, e.g., by virtue of a non-conductive surface coating on the subframe and/or the electrical device
Data Source
AI summary
A subframe assembly comprising a subframe and a conductive element installed to the subframe thereby defining a surface interface at a fixing point between the subframe and the conductive element. The subframe and the conductive element are electrically isolated at the surface interface. A fastener is configured to secure the conductive element to the subframe at the fixing point, and to provide an electrically conductive pathway between the subframe and the conductive element through the fastener.