Curved Welding Surface for Gas Expulsion in Active Bolster
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Solution Overview
Problem
The existing hot welding process for joining plastic walls in active vehicle bolsters can trap gas bubbles due to surface imperfections, leading to weak welds and reduced strength under high inflation pressures.
Innovation Solution
A curved welding surface on the attachment boss is used, where the apex makes first contact with the attachment pad, creating a contact edge that moves radially outward during compression to expel gas from the weld interface, preventing bubble formation and enhancing joint strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If flat welding surfaces are used for hot welding the bladder member to the reaction plate, then the manufacturing process is simple, but gas bubbles are trapped in the weld creating weak points that reduce joint strength
Solution Approach 1:
The attachment boss is designed with a curved welding surface instead of a flat surface. The curvature causes the contact edge to move radially outward during compression, expelling gas from the weld interface and preventing bubble formation. This maintains manufacturing simplicity while significantly improving weld joint strength by eliminating weak points caused by trapped gas.
2Strength
If the curved welding surface with apex contact is used, then gas is effectively expelled from the weld interface improving joint strength, but the manufacturing precision requirements increase
Solution Approach 1:
The welding surface geometry is changed from flat to curved with a specific apex configuration. This parameter change enables gas expulsion during welding while the curvature radius and apex position are optimized to balance the manufacturing precision requirements with the gas expulsion effectiveness, making the process feasible for production.
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 curved welding surface effectively displaces gas from the weld interface, resulting in a stronger and more reliable joint that resists separation under high pressures, improving the overall performance of the active bolster during crash events.
Implementation Method 1
The peripheral seal is formed by hot welding, for example. Hot welding involves heating of the matching surfaces and then compressing them together.
Implementation Method 2
Hot welding involves heating of the matching surfaces and then compressing them together.
Data Source
AI summary
An active bolster for an automotive vehicle includes a plastic-molded trim wall that deploys outwardly during a crash. A plastic-molded reaction plate is mounted as a deployment base. A plastic-molded bladder member is joined around a substantially sealed perimeter with the trim wall to form an inflatable bladder. The bladder member includes at least one substantially circumferential pleated baffle around a central attachment region. The central attachment region includes an attachment boss projecting toward an attachment pad on the reaction plate to form a hot weld. The attachment boss has an arched cross section defining a weld surface with an apex. The weld surface is hot welded to the attachment pad such that the apex makes first contact with the attachment pad, wherein compression of the bladder member with the reaction plate creates a contact edge moving radially outward from the apex to expel gas from the hot weld.