Pyrotechnic Actuator Subassembly with Guided Igniting Portion
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Solution Overview
Problem
Conventional explosive studs used in vehicle safety systems, such as airbag modules, are often oversized and expensive, failing to meet safety requirements and cost-effectiveness for applications requiring controlled release of tether activation units.
Innovation Solution
A pyrotechnic actuator subassembly with a movable igniting portion guided by a receiving element, where the igniting portion is restricted after activation, and a tether is fixed before activation to ensure controlled movement and safety, utilizing a plastic receiving element and snap-fit connections for cost-effective manufacturing and mounting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional explosive studs are used as actuator units, then they are robust and can absorb excessive forces, but they are oversized and too expensive for tether activation applications
Solution Approach 1:
The actuator system is divided into two functional parts: a robust holding portion that remains mounted and a movable igniting portion that is activated and discarded. This segmentation allows the expensive robust components to be used only when needed, while the activated portion can be simpler and more cost-effective for tether activation applications
Solution Approach 2:
The igniting portion is designed as a disposable component that is activated once and then discarded or retained in the firing head. This allows the use of cheaper materials and manufacturing methods for the igniting portion while maintaining robustness in the holding portion that remains in the system
2Ease of operation
If the igniting portion is made movable after activation, then tether release is enabled, but contact with vehicle occupants or damage to the system may occur
Solution Approach 1:
The firing head serves as an intermediary structure that guides the movement of the igniting portion. This intermediary component ensures that the igniting portion moves in a controlled manner along a predetermined path, enabling tether release while preventing uncontrolled movement that could contact occupants or damage the system
Solution Approach 2:
The guide structure for the igniting portion is pre-configured in the firing head before activation. This preliminary arrangement ensures that when the igniting portion becomes movable, its movement is automatically constrained to a safe predetermined path, eliminating the need for complex real-time control mechanisms
3Reliability
If a receiving element is added to guide the igniting portion, then safety requirements are met, but device complexity increases
Solution Approach 1:
The receiving element and guide structure are merged into a single integrated firing head component. This combination eliminates the need for separate guiding mechanisms while still providing the necessary constraints for safe igniting portion movement, thereby maintaining safety requirements 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 actuator subassembly provides a cost-effective, safely designed solution for pyrotechnic actuators with controlled movement, preventing contact with vehicle occupants and damage, while allowing reliable tether release, meeting all safety requirements with minimal manufacturing and mounting effort.
Implementation Method 1
a pre-fabricated electric igniting unit (18) including a pyrotechnic charge (20) is received
Data Source
AI summary
The invention relates to an actuator subassembly (10) for a vehicle safety system comprising a pyrotechnic actuator unit (12) including an igniting portion (14) as well as a receiving element (16) forming a guide for the movable igniting portion (14) after activating the actuator unit (12). Further the invention relates to an airbag module of a vehicle safety system comprising said actuator subassembly (10) and a method of mounting a releasable tether (30) on an airbag module by means of said actuator assembly (10).