Piston-Cylinder Unit Preload Sealing for Vehicle Safety Systems
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Solution Overview
Problem
Existing piston-cylinder units in vehicle safety systems face issues with reproducibility and stability, leading to unwanted movement and noise during vehicle operation, and inadequate sealing against environmental factors.
Innovation Solution
A piston-cylinder unit design featuring a detachable closure cap with a snap-in connection and preloading mechanism, which ensures precise positioning and sealing, minimizing unwanted movement and environmental exposure, and utilizing a pyrotechnic actuator for defined force application.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the closure cap is pressed onto the cylinder end to close the outlet opening, then the piston is positioned in the initial position and sealed against environmental influences, but the piston may wobble and generate rattling noises during vehicle operation
Solution Approach 1:
The closure cap is pre-loaded against the piston in the initial position, creating a preliminary positioning action that prevents wobbling and rattling before the piston moves. This pre-positioning ensures the piston starts in a stable, centered location within the cylinder.
Solution Approach 2:
The closure cap acts as an intermediary element between the piston and the cylinder outlet opening. It provides both sealing and positioning functions, mediating the interaction between the piston and environmental influences while preventing harmful rattling noises.
2Ease of manufacture
If the closure cap is made of plastic and pressed onto the cylinder, then it can be easily manufactured and attached, but it may not provide sufficient sealing against moisture and dirt particles
Solution Approach 1:
The closure cap utilizes a flexible plastic material that can be pressed onto the cylinder to form a tight sealing interface. The flexibility of the plastic shell allows it to conform to the cylinder surface, creating an effective barrier against moisture and dirt particles while maintaining ease of manufacture.
Solution Approach 2:
The closure cap is pre-loaded with a pressing force during assembly to ensure immediate and effective sealing upon attachment. This preliminary sealing action prevents environmental contaminants from entering the cylinder-piston assembly during the attachment process and subsequent operation.
3Productivity
If the piston is displaced from its initial position to the end position, then the pyrotechnic actuator can effectively move the piston through the outlet opening, but the closure cap must be detachable without being destroyed
Solution Approach 1:
The closure cap is designed as a separate, detachable component from the piston-cylinder assembly. This segmentation allows the cap to be easily removed or pushed away during piston actuation without being destroyed, while maintaining its integrity for potential reuse or replacement. The cap functions as an independent element that can be detached during high-speed piston movement.
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 reproducible and stable operation by preventing piston wobbling and rattling, ensuring effective sealing, and enabling precise control of the piston's movement, enhancing the overall performance and reliability of vehicle-integrated personal safety systems.
Implementation Method 1
The sealing cap also represents a sealing element, in that it seals the interior of the cylinder against undesirable environmental influences, such as moisture and dirt particles, against the area surrounding the cylinder
Implementation Method 2
The preferred embodiment of the invention provides for an in-unit pyrotechnic actuator to move the piston
Data Source
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AI summary
The piston-cylinder unit (2) has a cylinder (4), and piston bearing (12) that is displaceable in axial direction in the cylinder. The cylinder has a stop (34) for defining an end position of the piston. The piston has damping section for braking the piston before reaching the final position in which the damping portion is deformed, such that piston is displaceable in direction of its initial position. Independent claims are included for the following: (1) vehicle integrated personal safety system; and (2) method for producing piston-cylinder unit.