Riveted Pyrotechnic Switch Housing With Metal Insert Sealing
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Solution Overview
Problem
Pyrotechnic devices with multi-part housings face challenges in achieving a good seal and resistance to operating pressures, while being difficult to assemble due to weaknesses in the housing components.
Innovation Solution
A pyrotechnic switch design featuring a housing with a metal insert and a plastic body overmolded onto the metal insert, where the rivet contacts the metal insert rather than the plastic, ensuring the riveting force is absorbed by the metal, and a shouldered rivet base provides additional support to limit contact pressures and prevent radial stresses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the housing parts are fastened by clipping or bolts, then the assembly is easy, but the sealing and resistance to operating pressures are insufficient
Solution Approach 1:
The rivet is designed with a curved deformation path during installation, allowing it to swell and conform to the cylindrical passage opening in the metal insert. This curved engagement creates a reliable seal while maintaining ease of assembly through the self-centering nature of the cylindrical fit.
Solution Approach 2:
A metal insert with a cylindrical passage opening is introduced as an intermediary component between the rivet and the plastic housing. This metal intermediary transfers and distributes the riveting forces, preventing direct contact between the rivet and plastic, thereby ensuring both reliable sealing and ease of assembly.
2Reliability
If the housing parts are fastened by rivets, then the resistance to operating pressures is improved, but the assembly becomes complicated due to plastic weakness
Solution Approach 1:
The metal insert serves as a mediator that receives the rivet during assembly, protecting the plastic housing from direct riveting forces. The rivet swells within the metal insert's cylindrical passage, creating a secure connection without compromising the plastic, thus simplifying assembly while maintaining pressure resistance.
Solution Approach 2:
The housing combines plastic and metal materials, with the metal insert providing the rigid structural support needed for rivet engagement. This composite construction allows the plastic to provide sealing and insulation while the metal provides mechanical strength for pressure resistance and easy rivet assembly.
3Ease of manufacture
If the rivet contacts the plastic body directly, then the assembly is simple, but the plastic weakness causes sealing failures and structural damage
Solution Approach 1:
The metal insert with its cylindrical passage opening acts as an intermediary that the rivet contacts during assembly. This eliminates direct contact between the rivet and plastic body, preventing structural damage to the plastic while maintaining assembly simplicity through the self-centering cylindrical fit.
Solution Approach 2:
The metal insert is strategically placed only at the rivet engagement location, providing localized metal reinforcement where mechanical strength is needed. The rest of the housing remains plastic, maintaining its sealing and insulation properties, thus achieving local quality enhancement without overall complexity increase.
4Reliability
If a shouldered rivet base is used to limit contact pressures, then the sealing is improved, but the device complexity increases
Solution Approach 1:
The metal insert serves multiple functions: it provides a cylindrical passage for rivet insertion, acts as an intermediary to protect the plastic, distributes riveting forces through its rigid structure, and the shouldered base limits contact pressures. This multi-functionality improves sealing without significantly increasing device complexity.
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
The solution provides a robust and easily assembled pyrotechnic switch with enhanced sealing and resistance to operating pressures, maintaining structural integrity and simplifying the manufacturing process by eliminating radial forces on the plastic components.
Implementation Method 1
at least one out of the first housing part or the second housing part comprises a metal insert and a plastic body overmolded onto the metal insert
Implementation Method 2
the head of the rivet is initially cylindrical in order to be inserted into the passage opening. At the time of assembly, the head is deformed by the riveting tool to be flattened and widened.
Data Source
AI summary
A pyrotechnic switch comprises a housing formed by a first housing part and a second housing part, at least one rivet by means of which the first housing part is riveted onto the second housing part in order to form the housing, and at least one pyrotechnic actuator arranged in the housing. Further, at least one of the first housing part or the second housing part comprises a metal insert and a plastic body overmolded onto the metal insert, and the metal insert comprises a passage opening for the rivet such that the rivet is in contact with the passage opening of the metal insert.