Webbing Take-up Device Multi-Rotation Energy Absorption
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing webbing take-up devices for vehicle seatbelts limit the number of rotations of the spool from the start of deformation of a first energy absorption member to the start of deformation of a second energy absorption member to less than one rotation, restricting the effective energy absorption capacity.
Innovation Solution
A webbing take-up device design that includes a spool, a lock base, first and second energy absorption members, a rotating body, a coupling member, a lock member, and a restricting member, allowing the second energy absorption member to deform after the spool has rotated more than one rotation by releasing the movement restriction on the lock member after the rotating body has rotated once.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the lock ring is restricted from rotating by the lock portion abutting the switching face, then the structure is simple and reliable, but the number of rotations of the spool is limited to less than one rotation
Solution Approach 1:
The lock member is designed to transition from a restricted state to an unrestrained state dynamically. Initially, the restricting member prevents the lock member from engaging the engagement portion, allowing the spool to rotate more than one rotation. After one rotation, the restricting member releases the lock member, which then engages with the engagement portion to restrict further rotation. This dynamic state change resolves the contradiction by allowing both multi-rotation capability and structural reliability.
2Productivity
If the restricting member releases the lock member after one rotation, then the spool can rotate more than one rotation, but the structure becomes more complex
Solution Approach 1:
The lock member serves multiple functions: it acts as both a rotation restriction mechanism (by engaging with the engagement portion) and as a component that interacts with the restricting member to enable multi-rotation. The restricting member integrates the function of controlling when the lock member becomes active. By merging these functions into fewer components, the design achieves multi-rotation capability without excessive structural complexity.
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 the spool to rotate beyond one rotation, enhancing the energy absorption capacity by allowing both the first and second energy absorption members to deform, thereby increasing the effective energy absorption during the pull-out process.
Implementation Method 1
the main torsion shaft undergoes twisting deformation
Implementation Method 2
the sub torsion shaft also undergoes twisting deformation
Data Source
AI summary
A webbing take-up device is obtained in which the number of rotations of a spool from the start of deformation of a first energy absorption member until the start of deformation of a second energy absorption member can exceed one rotation. In a webbing take-up device, a restricting tab is provided at an open side of the engagement recess portion. Although the leading end of the stopper pawl and the engagement recess portion face each other in the first rotation of the lock ring, a leading end of a stopper pawl is thereby unable to enter inside the engagement recess portion. The restricting tab is restricted from rotating when the leading end of the stopper pawl abuts an abutting portion of the restricting tab. When the lock ring accordingly rotates in a pull-out direction, the restricting tab moves relative to the open side of the engagement recess portion. When the leading end of the stopper pawl and the engagement recess portion face each other in this state, the leading end of the stopper pawl is thereby able to enter the engagement recess portion.