Belt Retractor Switchable Force-Limiting Coupling Mechanism
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Solution Overview
Problem
The existing belt retractor systems require switching from a lower to a higher force limiting level before completing a full rotation of the belt shaft, which is not flexible enough to accommodate scenarios where this switch is needed later, such as after multiple rotations with respect to a locked profile head.
Innovation Solution
Incorporating a bridging device that initially supports the coupling element on the connecting tube's surface, preventing the locking hook from latching into the locking groove until a preset angle is reached, allowing the belt shaft to rotate multiple times before engaging the higher force limiting level, with options including a spacer or a catch mechanism for adjustable switching times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the locking hook is allowed to latch into the locking groove immediately upon rotation, then the force limiting level switches earlier, but this reduces the flexibility to delay switching until after multiple rotations
Solution Approach 1:
The bridging device acts as an intermediary between the coupling element and the locking groove. It temporarily prevents the locking hook from engaging with the locking groove during initial rotations, then releases it at the predetermined angle. This mediator mechanism enables delayed switching while maintaining a relatively simple overall structure.
Solution Approach 2:
The bridging device is pre-configured to interfere with the locking hook's path to the locking groove during initial rotations. This preliminary action of blocking engagement allows the system to delay the force limiting level switch until the desired rotation angle is reached, providing flexibility in switching timing.
2Adaptability or versatility
If the bridging device is removed, then the structure is simpler, but the belt shaft cannot rotate multiple times before engaging the higher force limiting level
Solution Approach 1:
The bridging device creates a dynamic engagement sequence where the coupling element's interaction with the locking groove is controlled over time. Initially, the bridging device prevents engagement, allowing multiple rotations. At the predetermined angle, the bridging device moves away, enabling the locking hook to latch into the locking groove and switch to the higher force limiting level.
Solution Approach 2:
The force limiting device is segmented into two functional stages: the first stage allows free rotation with the bridging device blocking engagement, and the second stage engages the locking mechanism at the predetermined angle. This segmentation enables multiple rotations before switching while maintaining a manageable device structure.
3Adaptability or versatility
If the locking hook engages the locking groove immediately, then the higher force limiting level activates sooner, but this prevents adaptation to scenarios requiring delayed engagement after multiple rotations
Solution Approach 1:
The bridging device performs a preliminary blocking action that prevents the locking hook from engaging the locking groove during initial rotations. This preliminary interference with the engagement process creates a controllable time delay, allowing the system to adapt to operational scenarios where delayed activation of the higher force limiting level is required.
Solution Approach 2:
The system transitions from a static immediate-engagement design to a dynamic controlled-engagement design. The bridging device enables the locking mechanism to remain disengaged during initial rotations, then dynamically engages at the predetermined angle, providing adaptability to varying operational requirements while controlling the timing of force limiting level switching.
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
Enables switching from the low to high force limiting level after multiple rotations of the belt shaft, enhancing flexibility and ensuring the belt retractor can adapt to varying operational requirements without premature engagement.
Implementation Method 1
a coupling element, arranged between the belt shaft and the connecting tube, which is configured as a spring element with a locking hook that slides over the outer periphery of the connecting tube during rotation of the belt shaft including the coupling element and, when the preset angle of rotation of the belt shaft is reached, drops into a locking groove formed on the periphery of the connecting tube
Data Source
AI summary
A vehicle seat belt retractor with a belt shaft (10) and a coupled profile head lockable to a housing. A force-limiting device has at least two elements (11, 12) between profile head and belt shaft (10). Free ends (15, 16) of the force-limiting elements (11, 12) are coupled to each other by a connecting tube (13) via a coupling element (18). The coupling element (18) has a hook-shaped spring element with a locking hook (19) which slides over the connecting tube (13) when the belt shaft (10) rotates and engages in a locking groove (20) to couple the connecting tube (13) to the belt shaft (10). At a preset angle of rotation of the belt shaft (10) is reached, the bridging device releases the coupling element (18) for the locking hook (19) to latch into the connecting tube locking groove (20).