Webbing Take-Up Device Load Path Segmentation
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Solution Overview
Problem
Existing webbing take-up devices face limitations in material selection and compact design for the shaft portion due to load input from the lock member, which restricts the choice of materials and dimensions.
Innovation Solution
A webbing take-up device with a lock base and lock member where the shaft portion is integrated as a single body with the load bearing portion, allowing the load to be input to the load bearing portion rather than the shaft portion, enabling separation of load input surfaces and thus eliminating the need for strong or rigid material selection for the shaft portion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the shaft portion is engaged by the lock member to transmit load, then the lock mechanism can function properly, but the material selection for the shaft portion is limited and the shaft portion cannot be made more compact
Solution Approach 1:
The invention divides the load transmission path into two separate functional zones: the shaft portion insertion hole provides rotational support and positioning, while the load bearing portion receives and transmits the load. This segmentation allows the shaft portion to be made of lightweight materials without compromising load-bearing capability, thus resolving the contradiction between reliability and material selection freedom.
Solution Approach 2:
The load bearing portion acts as an intermediary element between the lock member and the shaft portion. When the lock member engages with the ratchet teeth, the load is transmitted through the load bearing portion rather than directly to the shaft portion. This intermediary structure enables the shaft portion to be compact and made from various materials while maintaining proper lock mechanism function.
2Reliability
If the shaft portion is engaged by the lock member to transmit load, then the lock mechanism can function properly, but the shaft portion dimensions are constrained and compact design is impeded
Solution Approach 1:
The invention divides the load transmission path into two separate functional zones: the shaft portion insertion hole provides rotational support and positioning, while the load bearing portion receives and transmits the load. This segmentation allows the shaft portion to be made of lightweight materials without compromising load-bearing capability, thus resolving the contradiction between reliability and material selection freedom.
Solution Approach 2:
The load bearing portion acts as an intermediary element between the lock member and the shaft portion. When the lock member engages with the ratchet teeth, the load is transmitted through the load bearing portion rather than directly to the shaft portion. This intermediary structure enables the shaft portion to be compact and made from various materials while maintaining proper lock mechanism function.
Data Source
AI summary
A webbing take-up device includes a spool, a lock base, and a lock member. The lock base includes a lock base body equipped with a load bearing portion, and a shaft portion. The lock member includes a shaft portion insertion hole for insertion of the shaft portion, and on actuation displaces from a housed position to an engaged position to limit rotation of the spool in the pull-out direction. Shapes and dimensions of the shaft portion and the shaft portion insertion hole are set such that, when a load accompanying pull-out of the webbing from the spool has been input from the lock member positioned at the engaged position to the lock base, the load is input from the lock member to the load bearing portion and an outer peripheral face of the shaft portion and an inner peripheral face of the shaft portion insertion hole are separated from each other.