Webbing Take-Up Device Pinion Diameter Reduction
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Solution Overview
Problem
Existing webbing take-up devices increase the diameter of the pinion and require longer racks to ensure adequate webbing take-up, which is inefficient and costly.
Innovation Solution
A webbing take-up device configuration where the first and second members, with pinion-configuring portions, restrict rotation in the pull-out direction, and the second member is fixed to the torsion shaft, allowing for a smaller pinion diameter by utilizing a pinion section with teeth positioned radially inward and a secure fitting structure between members to efficiently transmit torque.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a pinion is provided as a separate body disposed at the outer circumferential side of a member that is restricted from rotating in the pull-out direction by the lock portion, then the webbing take-up function is achieved, but the diameter of the pinion is increased and the rack becomes longer
Solution Approach 1:
The invention merges the pinion function into the lock base by forming pinion teeth directly on the outer circumferential surface of the lock base. This integration eliminates the need for a separate pinion component, reducing the overall pinion diameter and rack length while maintaining the webbing take-up function. The lock base simultaneously serves as both the locking mechanism and the pinion gear.
Solution Approach 2:
The lock base is designed to perform multiple functions: it restricts rotation in the pull-out direction through the lock portion, and simultaneously transmits rotational force in the take-up direction through the pinion teeth formed on its outer circumferential surface. This multi-functionality reduces the number of components and minimizes the pinion diameter.
2Quantity of substance
If the pinion diameter is increased to ensure adequate webbing take-up, then the webbing take-up capacity is improved, but the device size and manufacturing costs increase
Solution Approach 1:
By integrating the pinion teeth into the lock base structure, the invention achieves adequate webbing take-up capacity without increasing the overall device size. The combined structure allows for optimized space utilization and reduces manufacturing complexity, thereby lowering production costs.
Solution Approach 2:
The invention optimizes the parameters of the pinion teeth (such as tooth profile, module, and pitch) formed directly on the lock base to achieve the required webbing take-up capacity with a smaller effective diameter, reducing both device size and manufacturing costs.
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 configuration effectively suppresses the pinion diameter, ensuring efficient webbing take-up while reducing the device's size and costs, and enhancing torque transmission and manufacturability.
Implementation Method 1
a rack and the like for rotating the pinion are made longer in order to ensure that a given amount of webbing is taken up
Implementation Method 2
a pinion for rotating a spool in a take-up direction in a vehicle emergency is disposed at the outer circumferential side of a shaft portion of a lock base fixed to a torsion shaft
Data Source
Figure 1
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Figure 3
AI summary
In a vehicle emergency, rotation of a lock base (26) in a pull-out direction opposite to a take-up direction is restricted. A first pinion-configuring portion (60) formed at an outer circumferential portion of the lock base (26) configures one width direction side of a pinion section (50) that is rotated in the take-up direction by a rack that moves due to fluid pressure in a vehicle emergency. A coupling member (34) disposed between the lock base (26) and the torsion shaft (18) is fixed to the lock base (26) and to a torsion shaft (18). A second pinion-configuring portion (70) that configures a width direction other side of the pinion section (50) is formed alongside the first pinion-configuring portion (60) at an outer circumferential portion of the coupling member (34).