Automobile Airbag Door Bond Strength Difference Mechanism

Solution Overview

Problem

Existing automobile airbag doors require tear lines on both the base and cover members, which increases manufacturing complexity and costs, and there is a need for an airbag door where the cover member without a tear line can be torn along the tear line of the base member.

Innovation Solution

An automobile airbag door with a bond strength difference generating mechanism, where a tear line is formed only in the door base member, and the bond strength between the door base and cover members is weaker in a specific band-like zone along the tear line, allowing the cover member to be torn along the base member's tear line when pressed by the airbag.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If tear lines are formed on both the door base member and the door cover member, then the airbag door can be reliably opened during deployment, but the manufacturing complexity and costs increase

Engineering Contradiction:

Improvereliability of airbag door openingVSAvoidmanufacturing complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The invention extracts the tear line feature from the door cover member, retaining it only on the door base member. The door cover member is designed without a tear line, and instead relies on the bond strength difference between the first zone (weaker bonding) and second zone (stronger bonding) to enable tearing along the base member's tear line during airbag deployment, thereby simplifying manufacturing while maintaining reliability

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The invention applies local quality by creating a bond strength difference generating mechanism with different bonding characteristics in different zones. The first zone has weaker bond strength to facilitate tearing, while the second zone has stronger bond strength to maintain structural integrity, allowing the cover member to be torn along the base member's tear line without requiring a tear line on the cover itself

Inventive Principle:

Principle #3Local quality

2Strength

If the bond strength between door base member and door cover member is uniform, then the structural integrity is maintained, but the cover member cannot be torn along the base member's tear line

Engineering Contradiction:

Improvebond strength between base and cover membersVSAvoidease of forming tear line

Core Design Contradiction:

StrengthVSEase of manufacture

Solution Approach 1:

The invention applies local quality by creating a bond strength difference generating mechanism with different bonding characteristics in different zones. The first zone has weaker bond strength to facilitate tearing, while the second zone has stronger bond strength to maintain structural integrity, allowing the cover member to be torn along the base member's tear line without requiring a tear line on the cover itself

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The bonding area between the door base member and door cover member is segmented into at least two zones: a first zone with weaker bond strength and a second zone with stronger bond strength. This segmentation enables differential tearing behavior where the cover member tears along the base member's tear line while maintaining overall structural integrity

Inventive Principle:

Principle #1Segmentation

3Speed

If the door cover member is made easy to tear, then the airbag can deploy quickly, but the door cover member may peel off the door base member during normal use

Engineering Contradiction:

Improveairbag deployment speedVSAvoidstability of bond between base and cover members

Core Design Contradiction:

SpeedVSStability of the object's composition

Solution Approach 1:

The invention applies local quality by creating a bond strength difference generating mechanism with different bonding characteristics in different zones. The first zone has weaker bond strength to facilitate tearing, while the second zone has stronger bond strength to maintain structural integrity, allowing the cover member to be torn along the base member's tear line without requiring a tear line on the cover itself

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The bonding area between the door base member and door cover member is segmented into at least two zones: a first zone with weaker bond strength and a second zone with stronger bond strength. This segmentation enables differential tearing behavior where the cover member tears along the base member's tear line while maintaining overall structural integrity

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS8480121B2Automobile airbag door

Publication Date: 2013.07.09 TOYODA GOSEI CO LTD

AI summary

An automobile airbag door is formed by a door base member, a door cover member, and a tear line. The door base member and the door cover member form a part of a base member and a part of a cover member of an instrument panel, respectively. When pressed by an airbag being deployed and inflated, the door base member is torn from the tear line. The first zone is defined as the bonded part between the outer surface of the door base member and the door cover member which extends along the tear line and includes a part on which the tear line is projected. The second zones are on both sides of the first zone and extend along the tear line. The automobile airbag door has a mechanism that makes the bond strength in the first zone weaker than the bond strength in each second zone.