Gas Generator Igniter Anchorage via Retaining Projections

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Solution Overview

Problem

Plastic-coated igniter units in gas generators fail to maintain metal parts' anchorage during fires due to melting or softening, leading to unreliable electrical connections, and existing high-temperature-resistant plastics are costly and difficult to ignite effectively.

Innovation Solution

The igniter unit features laterally protruding retaining projections on the connecting lines, which are integrally formed and secure the lines within the igniter support, eliminating the need for high-temperature-resistant plastics and early ignition agents, while maintaining a compact design and low production costs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If standard plastic-coated igniter units are used, then production costs are low and processing is simple, but metal parts become unanchored when plastic melts or softens during fires

Engineering Contradiction:
Improveanchorage reliabilityVSAvoidfire resistance
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The connecting line is segmented into functional sections: an electrical conductor core, an insulating coating, and lateral retaining projections. This segmentation allows the retaining projections to provide mechanical anchorage independent of the plastic insulator's thermal stability, resolving the contradiction between low-cost standard plastics and fire-resistant anchorage reliability.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The retaining projections extend laterally from the connecting line in a direction perpendicular to the electrical current flow. This dimensional addition creates a mechanical interlock with the igniter support that remains effective even when the plastic insulator softens or melts during fire conditions, maintaining anchorage reliability without requiring high-temperature-resistant materials.

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

2Object-affected harmful factors

If high-temperature-resistant plastics are used, then fire resistance and anchorage stability improve, but material and processing costs increase significantly

Engineering Contradiction:
Improvefire resistanceVSAvoidproduction cost
Core Design Contradiction:
Object-affected harmful factorsVSEase of manufacture

Solution Approach 1:

The solution segments the anchorage function from the insulating function. The lateral retaining projections handle mechanical retention during fire, while the plastic insulator provides only electrical insulation. This allows use of inexpensive standard plastics without compromising fire resistance, as the projections maintain anchorage independently of plastic thermal properties.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The design accepts that the plastic insulator may degrade during extreme fire events, but the critical anchorage function is performed by the durable metal retaining projections. This allows use of low-cost standard plastics that don't require high-temperature resistance, reducing material and processing costs while maintaining overall system reliability through the projection-based anchorage.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

3Reliability

If early ignition agents are added to improve ignition reliability, then ignition performance improves, but thermal conductivity of the plastic decreases making ignition more difficult

Engineering Contradiction:
Improveignition reliabilityVSAvoidthermal conductivity
Core Design Contradiction:
ReliabilityVSUse of energy by moving object

Solution Approach 1:

The connecting line is segmented into the electrical conductor core and the insulating coating with retaining projections. This segmentation allows the insulator to focus solely on electrical insulation and mechanical retention, while ignition reliability is ensured by the projection design that maintains stable electrical contact and positioning, eliminating the need for early ignition agents that would compromise thermal conductivity.

Inventive Principle:
Principle #1Segmentation

4Reliability

If curved connecting leads are manufactured with precise positioning, then anchorage and electrical connection improve, but manufacturing complexity and difficulty increase

Engineering Contradiction:
Improveanchorage reliabilityVSAvoidmanufacturing complexity
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

Instead of curving the connecting leads to achieve anchorage, the invention inverts the approach by adding lateral retaining projections to straight connecting lines. This simplifies manufacturing significantly, as straight lines are easier to produce and position than curved leads, while the projections provide the necessary mechanical interlock with the igniter support for reliable anchorage.

Inventive Principle:
Principle #13The other way round (Inversion)

Data Source

PatentEP1972883B1Ignition unit for a gas generator
Publication Date: 2012.05.16 TRW AIRBAG SYSTEMS GMBH
  • EP1972883B1 patent drawingFigure 1~3
  • EP1972883B1 patent drawingFigure 4a~4d
  • EP1972883B1 patent drawingFigure 5a~6

AI summary

The ignition unit (10) has at least one primary charge (14), at least one oblong electrical connecting lead (16) connected to a further connection lead or metal contact in the region near the primary charge via a bridge wire or a metal igniter support with at least one opening (26) through at least one connecting lead passes. The at least one connecting lead has at least one sideways holding protrusion (38) arranged between the primary charge and the igniter support and protruding over an edge (40) of the associated opening.