Airbag Lining Puncture Weakening Geometry
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Solution Overview
Problem
Existing methods for weakening airbag linings to ensure proper deployment in motor vehicles are either aesthetically unsatisfactory, compromise tearing characteristics, or require additional processing steps, such as visible notches, chemical treatment, or filling perforations, which are not suitable for natural materials like leather.
Innovation Solution
A lining material with successively arranged and spaced punctures on the inner side of the airbag cover periphery, forming a weakening geometry that deviates from a straight line, allowing the punctures to penetrate the material without subsequent filling, ensuring consistent tearing characteristics and optical concealment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the lining material is scribed to create a deep incision for weakening, then the tearing characteristics are improved, but the notch gapes and becomes visible on the outer side of the lining
Solution Approach 1:
The incision is segmented into multiple discrete punctures arranged in sequence rather than a continuous deep cut. This segmentation allows the material to tear reliably along the puncture line while each individual puncture remains visually concealed, especially when filled with matching material
Solution Approach 2:
The solution moves from a two-dimensional surface notch to a three-dimensional approach by creating punctures with controlled depth and providing fill material that restores the surface contour. The weakening function is achieved through the subsurface puncture geometry while the visible surface remains intact
2Reliability
If the lining material is chemically dissolved or evaporated with a laser beam to create weakening, then the tearing characteristics are improved, but the edges harden and compress under climatic effects becoming visible
Solution Approach 1:
The continuous chemical or thermal treatment is segmented into discrete puncture points. Each puncture creates localized weakening without extending the hardened/compressed region along the entire weakening line, thus preventing visible distortion while maintaining reliable tearing at each puncture site
Solution Approach 2:
The punctures are designed to extend only to the necessary depth to create effective weakening without excessive penetration that would cause hardening and compression of the material edges. The depth is carefully controlled to achieve the minimum required for functional weakening while avoiding adverse material property changes
3Reliability
If perforations are produced in the lining to create weakening, then the tearing characteristics are improved, but the perforations must be filled in again after production and the lining needs to be returned to the finishing shop
Solution Approach 1:
The punctures are designed and positioned during the initial finishing process rather than being created afterward. The finishing shop applies the weakening geometry as part of the original treatment, eliminating the need for subsequent filling operations and returning the lining to another facility
Solution Approach 2:
The weakening function is merged with the finishing process. The same equipment or process that finishes the lining surface also creates the puncture pattern, combining two operations into one integrated workflow and eliminating intermediate handling steps
4Shape
If the depth of the incision is reduced to prevent gapping, then the visibility of the notch is improved, but the tearing characteristics are negatively influenced
Solution Approach 1:
The weakening function is achieved through multiple discrete punctures rather than a single shallow incision. The cumulative effect of several closely spaced punctures creates reliable tearing initiation while each individual puncture remains shallow enough to avoid visible gapping when filled
Solution Approach 2:
Each puncture is designed with specific local geometry and depth optimized for its function. The punctures have controlled dimensions that create sufficient stress concentration for reliable tearing while maintaining visual concealability, with each location tailored to the local material properties
Data Source
AI summary
In order to realize the required weakening geometries in a lining material for the hinged cover of an airbag, punctures are produced on the inner side of a lining material by a puncturing needle, wherein the punctures are intermittently produced in the lining material from the inner side, the weakening geometry deviates from a straight line to ensure constant, reliable and defined tearing characteristics of the lining material, wherein for producing the lines of arbitrary weakening geometries by the punctures, the puncturing needle is oriented relative to the desired line direction in one preferred embodiment of the invention, i.e., the cutting edge of the puncturing needle is aligned with the weakening geometry to be produced.