Vehicle Subframe Grounding Through Fastener-Conductive Interfaces

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

Conventional grounding methods for electrical devices on vehicles, particularly those mounted on subframes with surface coatings, are inefficient and can damage the coatings, and large grounding components are unsuitable for certain applications.

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 thread-forming bolts, ensuring electrical connectivity while preserving coating integrity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional grounding methods (ground straps or brackets) are used to ground electrical devices on subframes, then electrical connectivity is achieved, but the grounding components become large in size and may damage surface coatings

Engineering Contradiction:
Improveelectrical connectivityVSAvoidsize of grounding components
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent combines the grounding function with the existing fastening structure by integrating a conductive element into the fastener assembly. The fastener simultaneously performs mechanical fastening and electrical grounding functions, eliminating the need for separate ground straps or brackets. This merging of functions reduces component size and simplifies the overall grounding system while maintaining reliable electrical connectivity between the electrical device and vehicle body.

Inventive Principle:
Principle #5Merging (Combining)

2Reliability

If serrated fasteners are used to cut into coated surfaces to aid grounding, then electrical connectivity is improved, but the surface coating is removed in regions surrounding the fastener

Engineering Contradiction:
Improveelectrical connectivityVSAvoidcoating damage
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent introduces a conductive element as an intermediary component that bridges the electrical connection between the electrical device and vehicle body without requiring direct contact with or damage to the painted surface. This conductive element is integrated into the fastener assembly and makes contact with metallic surfaces that are already exposed (such as the subframe or mounting surfaces), thereby achieving reliable grounding without the need to cut through or remove protective coatings from surrounding areas.

Inventive Principle:
Principle #24Intermediary (Mediator)

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 damaging surface coatings and eliminating the need for large grounding components, maintaining corrosion resistance and electrical conductivity.

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

Methodology Applied
Scientific EffectElectrical Conduction: Conduction (electrical)

Implementation Method 2

employing thread-forming bolts

Methodology Applied
Scientific EffectPlastic Deformation: Plasticity

Data Source

PatentEP4651307A1Grounding of an electrical device in a vehicle
Publication Date: 2025.11.19 FORD GLOBAL TECH LLC
  • EP4651307A1 patent drawingFigure 1
  • EP4651307A1 patent drawingFigure 2
  • EP4651307A1 patent drawingFigure 3

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.