Webbing Take-up Device Axial Constraint Mechanism
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Solution Overview
Problem
Existing webbing take-up devices face inefficiencies in transmitting kinetic energy due to the rotating body's movement in the rotation axis direction when engaged by a moving member, leading to suboptimal webbing take-up and potential friction issues.
Innovation Solution
A webbing take-up device design that includes a spool, a rotating body, and a rotating body placement section with an abutted portion to restrict the rotating body's movement in the rotation axis direction, along with an energy absorption member like a torsion shaft to permit rotation in the pull-out direction, stabilizing the load and reducing friction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the moving member engages with the rotating body to rotate the spool in the take-up direction, then the webbing is taken up onto the spool, but the rotating body moves in the rotation axis direction which reduces kinetic energy transmission efficiency
Solution Approach 1:
The abutted portion is designed to preemptively counteract the unwanted axial movement of the rotating body before it occurs during engagement. By providing a pre-positioned abutment surface, the system prevents the energy-wasting axial displacement rather than correcting it after the fact, ensuring kinetic energy is transmitted efficiently to rotate the spool in the take-up direction
2Device complexity
If the rotating body is free to move in the rotation axis direction, then the structure is simpler, but kinetic energy transmission from the moving member to the rotating body becomes inefficient
Solution Approach 1:
The rotating body placement section is segmented into a pair of wall portions spaced apart to form a space, with the abutted portion provided to one of these wall portions. This segmentation allows the rotating body to be constrained axially without requiring a completely rigid or complex structure, maintaining simplicity while preventing energy loss through unwanted movement
3Ease of operation
If the spool and rotating body placement section are disposed adjacent to each other, then the abutted portion can be provided to the nearest wall portion, but this may cause friction between the spool and abutted portion
Solution Approach 1:
The abutted portion is specifically provided to the wall portion nearest to the spool, creating a localized constraint function at the most effective position. This local quality approach ensures the rotating body is properly positioned without requiring friction, as the abutment provides a clean, predetermined stop that guides the rotating body into the correct position during engagement
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 effectively restricts the rotating body's axial movement, stabilizes the engaged state, and efficiently transmits kinetic energy, reducing the rotation force required for webbing take-up while minimizing friction and maintaining load stability.
Implementation Method 1
the energy absorption member is a torsion shaft that undergoes torsional deformation in a rotation-circumferential direction of the spool
Data Source
AI summary
A webbing take-up device includes a spool. The webbing take-up device also includes a lock base and a coupling member that are provided so as to rotatable as an integral unit with the spool, and that engage with a rack so as to be rotated and to rotate the spool in a take-up direction when the rack is moved. The webbing take-up device further includes a rack housing section that includes a pair of wall spaced apart from each other in a rotation axis direction of the lock base and the coupling member so as to form a space in which the lock base and the coupling member are disposed. The rack housing section is provided with an abutted portion that is abutted by a part of the coupling member so as to restrict the lock base and the coupling member from moving in the rotation axis direction.