Steering Wheel Horn Switch Conductive Paths
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Solution Overview
Problem
The existing steering wheel airbag systems experience poor conductivity performance between the horn switch mechanism and the core metal due to variations in the contact state between the pin member and the clip, leading to inconsistent electrical connections.
Innovation Solution
The steering wheel incorporates a horn switch mechanism with a metal pin member locked to the core metal via an engagement member and a resin cap interposed between the pin member and the core metal, featuring multiple conductive connection paths to ensure reliable electrical connectivity, including a first connection path with a conductive engagement member and a second path with an inner and outer contact portion extending along the resin cap.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single engagement member (clip) is used to connect the pin member to the core metal, then the device complexity is reduced, but the reliability of electrical connection deteriorates due to contact state variations
Solution Approach 1:
The electrical connection path is segmented into multiple parallel paths: the first connection path through the engagement member (clip) and the second connection path through the resin cap. This segmentation ensures that if one path experiences contact variations, the other path maintains electrical connectivity, thereby improving reliability without significantly increasing overall device complexity
Solution Approach 2:
The resin cap serves as an intermediary conductive element that provides an alternative electrical connection path between the pin member and the core metal. This intermediary structure ensures stable electrical contact by distributing the connection through multiple contact points rather than relying on a single engagement member
2Reliability
If the resin cap contacts both the inner surface of the through hole and the outer surface of the pin member, then the conductivity performance is improved, but the device complexity increases due to additional contact interfaces
Solution Approach 1:
The resin cap performs multiple functions simultaneously: it provides electrical conduction through its conductive material, mechanical support for the pin member, and creates stable contact interfaces with both the through hole and pin member. This multi-functionality improves conductivity performance without proportionally increasing device 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
This configuration enhances the reliability and conductivity performance between the horn switch mechanism and the core metal, maintaining high conductivity even under axial forces from vehicle vibrations or operational movements, ensuring consistent horn device operation.
Implementation Method 1
an inner surface of the neck portion of the pin member rubs against an outer surface of the clip
Data Source
AI summary
A steering wheel, in which an airbag device is attached to a core metal, including a through hole for attachment of the airbag device, via a horn switch mechanism, the horn switch mechanism including: a metal pin member whose tip end portion is locked to the core metal via an engagement member to be engaged with the tip end portion in a state where the tip end portion is inserted into the through hole and which forms a part of an electrical circuit configured to operate the horn device; and a resin cap which is interposed between an inner surface of the through hole and an outer surface of the pin member, the steering wheel includes a plurality of connection paths configured to normally connect the pin member and the core metal in a manner of forming a part of the electrical circuit.