Seat-belt pretensioner coupling element release mechanism
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Solution Overview
Problem
Existing seat-belt pretensioner systems face issues with force limitation obstruction due to opposite rotating movements of the belt shaft and the need for a locking element to be brought to a ready position before release, which can lead to increased stress on the coupling element and require higher strength to absorb impacting forces.
Innovation Solution
A seat-belt pretensioner design featuring a coupling element fixed in the circumferential direction with a detachable connection and an engagement wheel that uses conical engagement sections to connect with the seat-belt shaft, allowing for a rotation movement that disengages the pretensioner drive wheel, eliminating the need for a ready position and reducing axial stress on the coupling element.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a locking element is used to couple the pretensioner drive wheel to the belt shaft, then the pretensioner can maintain the coupling during tensioning movement, but the locking element must first be brought to a ready position which increases the complexity and time of the release process
Solution Approach 1:
The invention extracts the blocking function from the coupling element itself and places it in a separate blocking device that is fixed in the housing. This allows the coupling element to be released simply by rotating the seat-belt shaft, eliminating the need to bring the coupling element to a ready position. The blocking device is disengaged by the rotation movement alone, simplifying the release process while maintaining reliable coupling during tensioning.
2Stability of the object's composition
If the locking element is fixed in the seat-belt strap extraction direction with respect to the housing, then it can provide stable coupling, but it requires higher strength to absorb impacting forces during release
Solution Approach 1:
The invention extracts the force-absorbing function from the coupling element and transfers it to the blocking device and housing structure. The coupling element only needs to transmit rotational motion, while the blocking device absorbs the impacting forces during release. This separation of functions reduces the strength requirements of the coupling element while maintaining stable coupling during operation.
3Reliability
If the coupling element is subjected to axial force to maintain coupling, then it can prevent relative rotation, but it experiences increased stress and requires higher form stability
Solution Approach 1:
The invention extracts the axial force transmission function from the coupling element and places it in the blocking device. The coupling element is only subjected to tangential forces from rotation, while the blocking device handles the axial forces. This separation significantly reduces the stress and form stability requirements of the coupling element.
4Ease of operation
If the locking element is released by turning the belt shaft, then the release process can be simple, but the locking element must first be brought to a ready position which adds time and complexity
Solution Approach 1:
The invention extracts the ready-positioning requirement from the release process. The blocking device is designed to be disengaged directly by rotation of the seat-belt shaft without requiring the coupling element to be brought to a ready position first. This eliminates the time and complexity associated with ready-positioning while maintaining ease of operation.
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 enables independent release of the coupling element from the pretensioner drive wheel with smaller external forces, avoiding the need to bring the locking element to a ready position and reducing the strength requirements of the coupling element, thus improving the force-limited seat-belt strap extraction process.
Implementation Method 1
an engagement wheel is provided to connect the seat-belt shaft with the pretensioner drive wheel which body engages with axially aligned, conical engagement sections into corresponding recesses on the seat-belt shaft or the pretensioner drive wheel and is secured on the pretensioner drive wheel in the circumferential direction by the coupling element
Implementation Method 2
The locking element is formed, for example, by a spring disk which is moved into a ready position by the activation of the tensioning movement in that it engages with spring arms in a fixed-housing gear
Data Source
AI summary
A seat belt pretensioner having a housing, a belt shaft (10), a load limiting device (70) and a pretensioner drive wheel (20) coupled to the belt shaft (10). A coupling element (60) is fixed to the drive wheel (20) via a detachable connection, and can be locked by a blocking device (90). An engagement wheel (50) is provided for connecting the belt shaft (10) with the pretensioner drive wheel (20) having engagement portions (51) engaging into corresponding recesses (12) on the belt shaft (10) or on the pretensioner drive wheel (20) and is fixed by the coupling element (60). The detachable connection can be disconnected by locking of the coupling element (60) and rotation of the belt shaft (10) in the belt webbing extraction direction, thereby the engagement wheel (50) undergoes relative rotation in relation to the pretensioner drive wheel (20) or to the belt shaft (10).