Webbing Take-Up Device Lock Base Serrated Flange Axial Constraint
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Solution Overview
Problem
Existing webbing take-up devices fail to effectively limit the movement of engaging portions in the axial direction relative to suppressing portions, leading to potential rotation and displacement issues during vehicle emergencies.
Innovation Solution
A webbing take-up device design that includes a spool, a rotating portion with an engaging portion and an abutting portion, a suppressing portion, and an energy absorbing member, which limits axial movement and rotation by engaging and abutting mechanisms, and a lock member that restricts pull-out direction rotation through a serrated portion and flange configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the engaging portion is allowed to move freely in the axial direction, then the rotating portion can rotate smoothly, but the engaging portion cannot be limited from moving away axially relative to the suppressing portion
Solution Approach 1:
The rotating portion is divided into functionally independent segments: the engaging portion for radial engagement with ratchet teeth, the abutting portion for axial contact with the suppressing portion, and the energy absorbing member for controlled deformation. This segmentation allows each component to perform its specific function without interfering with others, achieving reliable axial movement limitation while maintaining smooth rotation capability.
Solution Approach 2:
The solution addresses axial movement limitation by introducing a constraint mechanism in the axial dimension (through the abutting portion and suppressing portion) without affecting the radial engagement mechanism. This multi-dimensional approach allows the engaging portion to move freely in the axial direction for smooth rotation while the abutting portion provides the necessary axial constraint through a separate contact interface.
2Strength
If the energy absorbing member is made deformable to allow relative rotation, then rotational load can be absorbed, but the rotating portion may displace axially during deformation
Solution Approach 1:
The system separates the load absorption function (energy absorbing member) from the position stabilization function (abutting portion). The energy absorbing member deforms to absorb rotational load while the abutting portion independently maintains axial position stability by contacting the suppressing portion, preventing axial displacement during deformation.
Solution Approach 2:
The abutting portion is pre-positioned to contact the suppressing portion before any deformation occurs. This preliminary axial constraint ensures that when the energy absorbing member deforms under rotational load, the rotating portion cannot displace axially, as the abutting portion has already established the positional boundary.
3Ease of operation
If the engaging teeth are moved axially with respect to the ratchet teeth, then the engaging mechanism can operate, but rotation of the rotating portion cannot be effectively limited
Solution Approach 1:
The solution operates in two dimensions: the engaging portion handles radial movement for engagement operation, while the abutting portion handles axial movement for rotation limitation. By separating these functions into different spatial dimensions and contact interfaces, the system achieves both easy operation of the engaging mechanism and reliable limitation of rotation through the abutting portion's axial constraint.
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 device effectively limits movement and rotation of the engaging and lock members, ensuring the webbing is securely taken up and restraining occupants during emergencies by dispersing load and preventing concentration on specific components, thus enhancing safety and mechanical integrity.
Implementation Method 1
an energy absorbing member that couples the rotating portion and the spool to each other, that limits relative rotation of the spool with respect to the rotating portion, and that becomes deformed in a case in which a rotational load of relative rotation of the spool with respect to the rotating portion has exceeded a predetermined magnitude, to thereby allow relative rotation of the spool with respect to the rotating portion
Data Source
AI summary
A serrated portion is formed on an outer peripheral portion of a lock base body of a lock base of a webbing take-up device. Furthermore, a flange portion is formed on the outer peripheral portion of the lock base body. The flange portion is disposed on a vehicle front side with respect to the serrated portion. Triangular grooves of the serrated portion are closed by the flange portion. When the lock base becomes displaced in a vehicle rearward direction and the flange portion comes into abutting contact with a leg plate of a frame, further displacement of the lock base in the vehicle rearward direction is blocked. Due to this, engagement between the serrated portion and ratchet teeth of a ratchet hole in the leg plate can be maintained.