Igniter Assembly Resin Integration Backlash Reduction
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Solution Overview
Problem
Conventional igniter assemblies for gas generators in airbag apparatuses face challenges with backlash and insufficient engaging strength due to complex shapes and reliance on elastic deformation, which complicates design changes and affects long-term reliability.
Innovation Solution
The igniter assembly integrates a separate igniter body, metal collar, and holder using resin, with features like convex or concave portions and through-holes, eliminating the need for elastic deformation, allowing for simpler designs and enhanced engaging strength through resin integration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a complex holder shape with elastic deformation is used to prevent backlash, then engaging strength is improved, but device complexity increases and design changes become difficult
Solution Approach 1:
The holder is divided into a tubular body portion and a separate convex portion that is fitted into the tubular body. This segmentation allows the convex portion to provide the necessary engaging features (protrusions or recesses) for preventing backlash without requiring the entire holder to have a complex elastic deformation structure. The convex portion can be a simple geometric element that is easily manufactured and modified.
Solution Approach 2:
The elastic deformation function is extracted from the holder's overall shape and concentrated into the convex portion that fits into the tubular body portion. This allows the main tubular body to maintain a simple cylindrical shape while the convex portion provides the specific engaging features needed for backlash prevention. The separation enables independent optimization of each component.
2Reliability
If a fitted holder structure is used to maintain firm connection, then reliability is improved, but manufacturing complexity increases
Solution Approach 1:
The convex portion and tubular body portion are combined through a fitting structure where the convex portion is inserted into the tubular body. This merging provides firm connection and reliable engagement while keeping each component's individual shape simple. The fitting interface provides the necessary connection strength without requiring complex manufacturing processes for either component.
3Reliability
If protrusions or recesses are formed on the holder surface for connector connection, then connection reliability is improved, but holder structure complexity increases
Solution Approach 1:
The protrusions or recesses for connector connection are localized to the convex portion rather than being distributed throughout the entire holder structure. This local concentration of engaging features allows the main tubular body to remain simple while the convex portion provides the specific local geometry needed for reliable connector connection. Each local feature serves a specific function without complicating the overall structure.
Data Source
AI summary
An igniter assembly includes, an igniter body having an ignition portion and an electroconductive pin, a substantially cylindrical collar surrounding and retaining the igniter body, and a tubular holder disposed inside the collar and surrounding the electroconductive pin to connect the electroconductive pin to a connector. The igniter body, the collar, and the tubular holder are separate members, and are integrated by a resin (provided that the holder is not fitted by being inserted into the collar or a resin portion covering the collar). The tubular holder has a tubular body portion and a convex portion covered by the resin and formed on an outer circumferential surface of the tubular body portion in the diametrical direction or on an inner circumferential surface of the tubular body portion in the diametrical direction. A fitting portion is provided to the inner circumferential surface of the tubular body portion for fitting the connector.