Webbing Take-Up Device Radial Wire Positioning
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Solution Overview
Problem
Existing webbing take-up devices have limitations on the lengths of energy absorbing members, restricting the energy absorbing stroke due to interference between load absorbing wires during spool rotation.
Innovation Solution
A webbing take-up device design with a spool, first and second energy absorbing members, and a lock unit that allows for longer energy absorbing strokes by positioning the energy absorbing members to prevent interference, enabling the spool to rotate while restricting pullout rotation, thus allowing the webbing to be pulled out effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If the load absorbing wires are made longer to increase energy absorbing stroke, then the energy absorbing capability is improved, but the wires impede each other during spool rotation
Solution Approach 1:
The patent positions the retaining position of the second load absorbing wire further to the radial direction outside than the first load absorbing wire, creating a radial dimension separation. This dimensional arrangement allows both wires to be pulled out along different radial paths during spool rotation, preventing interference while maintaining long energy absorbing stroke capability.
Solution Approach 2:
The patent employs asymmetric positioning where the second load absorbing wire is retained at a position separated further away to the rotation radial direction outside from the central axis than the first load absorbing wire. This asymmetric arrangement creates different pullout trajectories for each wire, eliminating mutual interference during rotation while maximizing the energy absorbing stroke.
2Duration of action of moving object
If the lengths of load absorbing wires are increased, then the energy absorbing stroke is extended, but the device complexity increases due to stringent length limitations
Solution Approach 1:
The patent employs asymmetric positioning where the second load absorbing wire is retained at a position separated further away to the rotation radial direction outside from the central axis than the first load absorbing wire. This asymmetric arrangement creates different pullout trajectories for each wire, eliminating mutual interference during rotation while maximizing the energy absorbing stroke.
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 design allows for a longer energy absorbing stroke without limitations on the lengths of the energy absorbing members, effectively restraining the vehicle occupant during rapid deceleration by channeling the webbing pulling force into distorting the energy absorbing members.
Implementation Method 1
the lock base engages the first energy absorbing member with the spool and deforms the first energy absorbing member along a spool circumferential direction while pulling the first energy absorbing member out from the first insertion hole
Data Source
AI summary
When a retaining portion for a first load absorbing wire and a second insertion hole of a second load absorbing wire are aligned with each other in a spool radial direction, and a retaining portion for the second load absorbing wire and a first insertion hole of the first load absorbing wire are aligned with each other in a spool radial direction, the forming position of the retaining portion for the first load absorbing wire is set further to the spool radial direction outside than the second insertion hole so that the retaining portion of the first load absorbing wire and the second insertion hole do not align with each other along the spool axial direction in this state. Similarly the forming position of the retaining portion for the second load absorbing wire is set further to the spool radial direction outside than the first insertion hole.