Belt Tensioner Spacer for Thrust Means Ejection
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Solution Overview
Problem
State-of-the-art belt tensioners face issues where the thrust means can get caught at the stop, leading to incomplete ejection from the pressure reservoir, causing unintended influence on force limitation during reverse rotation, and complicating mounting processes.
Innovation Solution
A spacer is introduced between the piston and the thrust means, ensuring the thrust means is completely urged past the stop and out of the pressure reservoir, with the spacer's length equal to or greater than the stop's length, and a narrowed cross-section projection to prevent re-engagement, facilitating complete ejection and secure retention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the thrust means is designed to interact with the stop to prevent piston over-travel, then the piston is reliably constrained in its final position, but the thrust means may get caught at the stop and fail to eject completely from the pressure reservoir
Solution Approach 1:
A spacer element is introduced as an intermediary component between the piston and the thrust means. This spacer acts as a mediator that transmits the piston's motion to the thrust means while ensuring complete ejection past the stop projection, resolving the contradiction between reliable position control and complete ejection.
2Reliability
If the thrust means remains partially inside the pressure reservoir after tensioning, then the stop can effectively limit piston travel, but the thrust means gets urged back into the reservoir during force limitation and influences force limitation inadvertently
Solution Approach 1:
The spacer element ensures that the thrust means is completely extracted or removed from the pressure reservoir after the tensioning operation. By pushing the thrust means past the stop projection and out of the reservoir, the spacer eliminates the harmful unintended influence on subsequent force limitation operations.
3Ease of operation
If a spacer is introduced between the piston and thrust means to ensure complete ejection, then the thrust means is reliably pushed past the stop, but the device complexity increases
Solution Approach 1:
The piston assembly is segmented into distinct functional elements: the piston itself, the spacer element, and the thrust means. This segmentation allows each component to perform its specific function independently, with the spacer ensuring complete ejection while maintaining overall system reliability.
4Reliability
If the stop is designed to seal the pressure reservoir when the piston abuts on it, then the pressure reservoir is effectively sealed to prevent fluid leakage, but the thrust means cannot be completely ejected past the stop
Solution Approach 1:
The spacer serves as a mediator that enables the thrust means to pass through the sealing zone created by the stop. By positioning the spacer between the piston and thrust means, it ensures the thrust means is pushed past the stop projection while the piston itself maintains sealing contact with the stop.
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 solution prevents thrust means from getting caught, ensuring free movement and reliable force limitation, while simplifying the mounting process by allowing sequential insertion and fixation of components without resistance.
Implementation Method 1
a piston movably supported in the longitudinal direction in the pressure reservoir to which piston pressurized fluid can be applied and which in this way can be moved in a tensioning direction
Implementation Method 2
the piston seals the pressure reservoir. The stop and/or the piston are designed so that the pressure reservoir is sealed when the piston abuts on the stop. In this way the pressurized fluid, for example hot gas from an inflator, is prevented from flowing out of the pressure reservoir
Data Source
AI summary
In a belt tensioner (10) for a seat belt comprising an elongate pressure reservoir (12), a piston (18) movably supported in the pressure reservoir (12) in the longitudinal direction to which piston pressurized fluid can be applied and which in this way can be moved in a tensioning direction (S), a mechanical thrust means (20) interacting with the piston, the thrust means interacting with a gearwheel (22) and driving the same in the case of restraint, and comprising a stop (24) on which the piston (18) abuts in the tensioning direction in a final position, it is provided that between the piston (18) and the thrust means (20) a spacer (30) in the form of a separate member is provided which is dimensioned such that in the final position of the piston (18) the thrust means (20) is urged past the stop (24) by said spacer. Furthermore there is provided a method of mounting a belt tensioner of this type.