Webbing Take-Up Spring Retention Under Shock Compression
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Solution Overview
Problem
Existing webbing take-up devices face issues with compression coil springs falling out when subjected to shocks, such as during a drop, which compromises their functionality.
Innovation Solution
The device incorporates a spool, rotating body, restricting member, operating member, compression coil spring, boss portion, and housing section, where the boss portion and housing section limit displacement of the coil spring ends, preventing it from coming out, even under shock conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a compression coil spring is provided between the W pawl and V gear to urge the W pawl in one direction, then the operating function of the webbing take-up device is improved, but the compression coil spring may fall out when shock is imparted to the device
Solution Approach 1:
The compression coil spring is nested within a dedicated spring accommodation space formed in the V gear, with the spring engagement portion of the W pawl inserted into the spring. This nested structure ensures the spring remains confined within the V gear even under shock conditions, preventing it from falling out while maintaining its urging function on the W pawl
Solution Approach 2:
A spring engagement portion is introduced as an intermediary element between the compression coil spring and the W pawl. This engagement portion, formed on the W pawl, provides a secure interface that holds the spring in place while transmitting the urging force, thereby stabilizing the spring position during operation and shock events
2Ease of operation
If the compression coil spring is completely compressed toward one side, then the operating member can be positioned at the extreme position, but the spring may exit from between engagement portions
Solution Approach 1:
The spring accommodation space is nested within the V gear structure, providing a confined environment that holds the compression coil spring securely. Even when the spring is completely compressed toward one side during operation, the nested structure prevents it from exiting the engagement portions by confining it within the dedicated space
Solution Approach 2:
The spring accommodation space extends in the radial direction of the V gear, creating an additional dimensional constraint. This radial extension provides extra space that accommodates the spring's compression movement while preventing it from exiting axially, thus allowing extreme positioning of the operating member without spring ejection
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 compression coil spring from exiting between engagement portions, ensuring reliable operation and preventing webbing ejection during sudden movements.
Implementation Method 1
The compression coil spring is provided between the first spring engagement portion and the second spring engagement portion, and urges the operating member toward the first position side
Data Source
AI summary
A webbing take-up device includes a spool, a V gear that includes a first spring engagement portion, a W pawl that includes a second spring engagement portion, and a return spring provided between the first spring engagement portion and the second spring engagement portion. A boss portion that is provided to the first spring engagement portion is inserted into a one-side of the return spring. A housing section is provided to the second spring engagement portion, with an other-side of the return spring housed therein. Displacement of an end portion on the second spring engagement portion side of the return spring is limited by the housing section in a state in which the W pawl is positioned at a reset position, and in a state in which the return spring is completely compressed toward the first spring engagement portion side.