Micro Gas Generator Housing With Insert-Molded Igniter Support
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Solution Overview
Problem
The manufacture of micro gas generators for vehicle safety systems is complex and costly due to the need for handling pyrotechnical igniters during injection-molding, requiring sophisticated processes and protective measures, and machined metallic holders are expensive.
Innovation Solution
A micro gas generator design featuring a plastic housing part injection-molded around a metallic insert, with a seat for the igniter, allowing separate fabrication of the housing part and igniter, and incorporating a fixing cap or propelling charge container for stabilization and sealing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If injection-molding is performed around the igniter, then the housing part can be manufactured integrally with igniter support, but complex protective measures and sophisticated processes are required
Solution Approach 1:
The manufacturing process is divided into two independent stages: first, the plastic housing part is injection-molded without the igniter present; second, the igniter is inserted into the pre-formed housing part. This segmentation eliminates the need for complex protective measures during injection-molding while still achieving integral construction of the housing part with igniter support features.
Solution Approach 2:
The housing part is prepared in advance with integrated support structures (such as recesses, friction-fit features, or threaded holes) that are designed to receive and secure the igniter after molding. This preliminary action allows the housing part to be manufactured using standard injection-molding processes without requiring the igniter to be present during the molding process.
2Reliability
If machined metallic holders are used, then igniter support and pressure resistance are achieved, but manufacturing costs increase significantly
Solution Approach 1:
The material parameter is changed from metal to plastic for the housing part, while compensating for mechanical properties through design features such as reinforced ribs, integrated metallic inserts in critical areas, or optimized geometric structures that provide sufficient strength and pressure resistance without requiring expensive machined metallic holders.
Solution Approach 2:
The housing part combines plastic material with integrated support structures that may include metallic inserts or reinforcement elements only where absolutely necessary. This composite approach maintains the cost advantages of plastic injection-molding while providing localized metal strength where required for igniter support and pressure resistance.
3Device complexity
If the igniter is inserted after housing part completion, then manufacturing complexity is reduced, but additional assembly steps are required
Solution Approach 1:
The igniter insertion step is combined with other assembly operations performed after injection-molding, such as installing the propelling charge, assembling the firing mechanism, or final housing closure. This merging of operations minimizes the impact on overall productivity while maintaining the manufacturing simplicity benefits of separate igniter insertion.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Facilitates manufacturing by eliminating the need for protective measures during injection-molding, reduces costs, and enhances mechanical stability and sealing, while maintaining igniter stability and assembly integrity.
Implementation Method 1
the plastic material forming the housing part is injection-molded around the insert and, thus, the insert is positively connected to the housing part
Implementation Method 2
the seat is configured so that, after being inserted, the igniter is held frictionally in the seat
Data Source
AI summary
The invention describes a micro gas generator (10) for a vehicle safety system comprising a plastic housing part (20) and a metallic insert (22), wherein the plastic material forming the housing part (20) is injection-molded around the insert (22) and, thus, the latter is positively connected to the housing part (20), and wherein a seat (24) in which an igniter (14) is inserted is formed in the housing part (20). In addition, a method of manufacturing a micro gas generator (10) is described.