Airbag Cover Weakening Pattern for Misalignment Tolerance

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

Existing airbag cover layers face challenges in aligning predetermined breaking zones during manufacturing and assembly, leading to potential mismatches that increase opening forces and delay or reduce airbag inflation, especially when dealing with translational and angular mismatches between layers.

Innovation Solution

An airbag cover layer with a predetermined breaking zone featuring a main extension and multiple weakenings that intersect each other, forming a zigzag or undulating tear line, allowing for alignment even with translational and angular mismatches, and designed to be easily broken during inflation, with weakenings that vary in length, orientation, and shape to distribute breaking force effectively.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If multiple airbag cover layers are used with separate predetermined breaking zones, then aesthetic appearance and material selection flexibility are improved, but alignment precision between layers deteriorates leading to mismatch

Engineering Contradiction:
Improvematerial selection flexibilityVSAvoidalignment precision between layers
Core Design Contradiction:
Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent combines the predetermined breaking zones of multiple airbag cover layers into a single integrated zone. The outer layer's breaking zone is designed to overlap and align with the inner layer's breaking zone, creating a unified breaking region that functions as one system rather than separate zones requiring precise alignment.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent introduces a width dimension to the breaking zone concept. By making the breaking zone sufficiently wide in the transverse direction, the design tolerates positional variations and angular mismatches between layers, transforming a precise point/line alignment problem into a broader area overlap problem that is less sensitive to manufacturing variations.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Force

If narrow predetermined breaking zones are used to maintain precision, then breaking force is reduced, but tolerance to misalignment deteriorates

Engineering Contradiction:
Improvebreaking forceVSAvoidtolerance to misalignment
Core Design Contradiction:
ForceVSAdaptability or versatility

Solution Approach 1:

The patent resolves this contradiction by expanding the breaking zone in the transverse width dimension while maintaining controlled characteristics in the longitudinal direction. This creates a broader overlap area that tolerates misalignment without significantly increasing the breaking force, as the width expansion provides alignment tolerance without proportionally increasing the total breakable material cross-section.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The patent applies different characteristics to different parts of the breaking zone. The zone is designed with specific width variations and weakening patterns that create regions of different breaking resistance, allowing the central overlapping region to be optimized for low breaking force while peripheral regions provide structural support and alignment tolerance.

Inventive Principle:
Principle #3Local quality

3Adaptability or versatility

If wide predetermined breaking zones are used to tolerate misalignment, then alignment tolerance is improved, but breaking force increases

Engineering Contradiction:
Improvealignment toleranceVSAvoidbreaking force
Core Design Contradiction:
Adaptability or versatilityVSForce

Solution Approach 1:

The patent makes different portions of the breaking zone have different breaking characteristics. The central overlapping portion is designed with maximum width and strongest weakening to provide alignment tolerance and minimal breaking force, while peripheral portions have reduced width or stronger material properties to limit the total breaking force increase.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent varies parameters such as width, material density, and weakening pattern throughout the breaking zone. By changing these parameters spatially, the design achieves broad alignment tolerance in the width direction while controlling the overall breaking force through strategic placement of high and low resistance regions.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP2878497B1Airbag cover layer and airbag cover
Publication Date: 2018.02.21 VOLVO CAR CORP
  • EP2878497B1 patent drawingFigure 1~2c
  • EP2878497B1 patent drawingFigure 3~4
  • EP2878497B1 patent drawingFigure 5~6

AI summary

The present disclosure relates to an airbag cover layer (18) comprising a predetermined breaking zone (20), the predetermined breaking zone (20) having a main extension and a plurality (24) of weakenings (26, 28, 30, 32, 34; 42, 44, 46, 48, 50) arranged along the main extension. At least one weakening of the plurality intersects a preceding weakening and also intersects a subsequent weakening. The disclosure further relates to an airbag cover (14, 14') comprising such an airbag cover layer (18).