Actuator Operating Pin Forward Movement Restriction
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Solution Overview
Problem
Existing actuators for airbag systems face issues with reliably preventing forward movement of the piston before operation and ensuring swift rearward movement of the operating pin upon activation, due to design limitations that can lead to incomplete gas injection and piston movement restrictions.
Innovation Solution
The actuator design incorporates a piston with an operating pin, a squib for generating driving gas, and a cylindrical case with injection holes around the operating pin, where the piston is initially restricted by the ceiling wall and gas is injected through these holes to facilitate swift rearward movement upon operation, utilizing both pressure and reaction force for efficient pin movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the injection hole is disposed at a vicinity of the ceiling wall portion before the actuator is operated, then the structure is compact, but the injection hole may move toward the ceiling wall portion and be closed by the ceiling wall portion when the piston moves forward before operation
Solution Approach 1:
The injection hole is configured to inject driving gas in the axial direction of the operating pin (parallel to the pin axis) rather than in a radial direction. This dimensional change in gas injection orientation ensures that the injection path remains clear even when the piston moves forward before operation, preventing the injection hole from being blocked by the ceiling wall portion while maintaining compact structure.
2Reliability
If the positioning member is arranged at a position where it is exposed outward from the cylinder case, then the rearward movement of the piston before being operated is restricted, but the forward movement of the piston cannot be firmly restricted
Solution Approach 1:
The positioning function is segmented into two independent components: the positioning member that restricts rearward movement, and the front end wall portion of the piston that restricts forward movement. This segmentation allows each component to be optimized for its specific direction of constraint without interfering with the other, achieving firm bidirectional positioning control.
Solution Approach 2:
The piston's own front end wall portion serves as the forward movement restriction element, eliminating the need for a separate forward positioning member. The piston structure itself provides the positioning function by having its front end wall contact the ceiling wall portion to prevent forward movement, simplifying the overall positioning structure.
3Ease of operation
If the operating pin has a diameter smaller than the outer diameter of the front end wall portion, then the pin can move freely, but the pin may move before the actuator is operated
Solution Approach 1:
The front end wall portion of the piston is designed to contact the ceiling wall portion before the actuator is operated, creating a preliminary mechanical constraint that prevents the operating pin from moving forward. This preliminary anti-action counteracts any forces that might cause premature pin movement, ensuring the pin remains stable until activation.
Solution Approach 2:
The operating pin is configured to move in the axial direction of the piston, perpendicular to the contact surface between the front end wall portion and ceiling wall portion. This dimensional arrangement allows the pin to move freely in its operational direction while the wall contact provides constraint in the opposite direction, achieving both freedom of operation and positional stability.
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
This configuration effectively prevents forward piston movement before activation and ensures swift, reliable rearward movement of the operating pin, improving the actuator's operational efficiency and reducing the risk of gas leakage.
Implementation Method 1
a squib which can generate driving gas upon being ignited when the actuator is operated
Implementation Method 2
around the operating pin of the cap portion is arranged a plurality of injection holes capable of injecting the driving gas from the gas injection port into the space between the front end wall portion and the ceiling wall portion inside the cylinder case
Data Source
AI summary
An actuator which has an operating pin of the invention includes a piston which has an operating pin, a squib, and a cylinder case for holding the piston, in which the piston is moved rearward along with the operating pin by a driving gas generated injected from the squib into the cylinder case. A cap portion for covering the side of the squib with a gas injection port comprises a cylindrical side portion and a front end wall portion, and the operating pin is projected from the center of this front end wall portion. The cap portion is arranged with injection holes through which the driving gas is injected. Forward movement of the piston before the actuator is operated is restricted by the front end wall portion of the cylinder case coming into contact with the ceiling wall portion of the cylinder case.