Belt Retraction Coupling with Breaking Point
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Solution Overview
Problem
Existing self-locking belt retractors face interference between emergency and pretensioning devices during pyrotechnic events, leading to potential destruction due to peak forces when the coupling member is re-actuated by the pretensioning device during high-speed belt shaft rotation.
Innovation Solution
The coupling part is designed with a predetermined breaking point and mass inertia or a centrifugal clutch to ensure it lags behind or separates from the belt shaft during emergency tensioning, preventing re-engagement with the pretensioning device and thus avoiding destructive peak forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the coupling member is designed to be re-engagable by the pretensioning device during emergency tensioning, then the pretensioning device can continue to function, but the coupling part may be re-actuated causing destructive peak forces
Solution Approach 1:
The coupling part is segmented into a first coupling part connected to the belt shaft and a second coupling part connected to the pretensioning device, with a predetermined breaking point between them. During emergency tensioning, the first coupling part separates from the second coupling part at the breaking point, preventing the pretensioning device from re-engaging the rapidly rotating belt shaft and causing destructive forces.
Solution Approach 2:
The predetermined breaking point is pre-designed in the coupling part to fail under specific conditions. When the belt shaft rotates at high speed during emergency tensioning, the breaking point automatically fails, preliminarily preventing any potential re-engagement of the coupling member by the pretensioning device before destructive forces can occur.
2Power
If the coupling connection between the belt shaft and pretensioning device is maintained during emergency tensioning, then the pretensioning device can assist emergency tightening, but it interferes with the emergency tensioning device effectiveness
Solution Approach 1:
The first coupling part is extracted from the complete coupling connection during emergency tensioning. When the belt shaft rotates at high speed, the first coupling part separates from the second coupling part at the predetermined breaking point, removing the pretensioning device from the power transmission path and eliminating its interfering effect on emergency tightening.
Solution Approach 2:
The coupling connection is designed to be dynamic rather than static. The coupling part automatically transitions from an engaged state during normal operation to a separated state during emergency tensioning when the belt shaft exceeds a certain rotational speed, allowing the system to adapt to different operational conditions.
3Ease of operation
If the coupling member is returned to release position by the rapidly rotating belt shaft, then the pretensioning device is released, but the coupling member may be re-actuated by the pretensioning device during high-speed rotation
Solution Approach 1:
The predetermined breaking point is pre-designed to fail when the coupling part experiences the high-speed rotation conditions. This preliminary action ensures that before any re-actuation can occur, the breaking point has already failed and the first coupling part has separated, preventing peak forces from developing.
Solution Approach 2:
The potential harmful effect of the pretensioning device re-actuating the coupling member during high-speed rotation is converted into a benefit. The predetermined breaking point is designed to fail under these exact conditions, using the high-speed rotation itself as the trigger for separation, thereby preventing the harmful peak forces that would otherwise occur.
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 design effectively prevents the pretensioning device from interfering with the emergency tensioning device, ensuring safe operation by maintaining the coupling separation and preventing further action by the pretensioning device during emergency situations.
Implementation Method 1
the coupling part is designed with a large mass inertia, which causes it to remain stationary in relation to the rapidly rotating belt shaft
Implementation Method 2
a centrifugal clutch controlled by the initial rapid rotation of the clutch part together with the belt shaft centrifugal forces in engagement with another component of the belt retractor is arranged on the coupling part
Data Source
Figure 1
Figure 2~3
Figure 4~6
AI summary
A self-locking belt retractor with an emergency tensioning device for the belt shaft and with a second tensioning device designed as a reversibly operating pretensioning device, wherein the emergency tensioning device is designed with a greater rotational speed and a coupling is arranged between pretensioning device and belt shaft, is characterized in that that coupling part (17) of the coupling which is connected to the belt shaft (14) is fastened releasably to the belt shaft (14) via at least one predetermined breaking point (40) and is designed in such a manner that, when the emergency tensioning device (15) is triggered, the coupling part (17) lags behind the belt shaft (14), which is rotated at the greater rotational speed, until the at least one predetermined breaking point (40) tears.