Steering Wheel Detent Pin Embedding for Airbag Module Alignment
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Solution Overview
Problem
The existing snap-fit connections between steering wheels and airbag modules in vehicles face challenges in maintaining precise tolerances and holding forces, especially when the airbag module needs to be movable for horn actuation, while also requiring a detachable and cost-effective solution that compensates for inaccuracies during foam covering of the steering wheel skeleton.
Innovation Solution
The detent pin is positively embedded in the foamed steering wheel cover, allowing for accurate positioning and alignment with the airbag module, combining a high-holding-force snap-fit connection between the module and the steering wheel skeleton with a low-holding-force connection between the module and the foamed cover, ensuring small gap widths and mobility, and optionally using a screw connection for additional stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a detachable snap-fit connection is used between the airbag module and steering wheel skeleton, then ease of assembly and disassembly is improved, but holding force and positioning precision deteriorate
Solution Approach 1:
The connection system is segmented into multiple independent detent pins that can be individually engaged and disengaged. Each detent pin acts as a separate fastening element, allowing the airbag module to be securely held during normal operation while enabling quick release when needed by simply pressing the release mechanism.
Solution Approach 2:
The detent pins incorporate a dynamic release mechanism that transitions the connection from a locked state to an unlocked state. The pins are designed to be rigid during normal operation to maintain holding force, but can be easily actuated to release the connection when the horn button is pressed or during airbag deployment.
2Adaptability or versatility
If the airbag module is made movable for horn actuation, then functionality is improved, but positioning precision and gap control deteriorate
Solution Approach 1:
The airbag module is granted mobility in the axial direction (toward and away from the steering wheel skeleton) while maintaining fixed positioning in radial directions. This dimensional differentiation allows the module to move for horn actuation while the detent pins constrain it in other dimensions to maintain precise gap control and alignment with the steering wheel cover.
3Ease of manufacture
If tolerance requirements are increased for cost reduction, then manufacturing cost is improved, but alignment precision and gap control deteriorate
Solution Approach 1:
The detent pins serve a dual function: they provide the fastening connection while simultaneously acting as self-aligning features. The pins are positioned on the steering wheel skeleton such that they automatically guide and align the airbag module during assembly, compensating for tolerance variations in the foam cover and ensuring consistent gap widths without requiring additional alignment fixtures or complex positioning mechanisms.
4Ease of repair
If the detent pin connection is made detachable for workshop operation, then ease of repair is improved, but connection stability deteriorates
Solution Approach 1:
The connection system incorporates a dynamic state transition between locked and unlocked positions. During normal vehicle operation, the detent pins maintain a stable locked state providing strong holding force. During workshop repair operations, a simple actuation mechanism allows the pins to transition to an unlocked state, enabling easy disassembly. The same mechanism that provides stability during operation also enables controlled instability during repair.
Data Source
AI summary
A steering wheel for an automotive vehicle comprising an airbag module and a detachable snap-fit connection for fastening the airbag module to the steering wheel includes a detent pin that is positively embedded in the foamed steering wheel cover of the steering wheel.