Seat Belt Retract Locking Base Contact Prevention
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Solution Overview
Problem
In seat belt retractors, high loads or pretensioner activation can cause the spool to become decentered, leading to increased resistance due to contact between the locking base and the base frame, which hinders smooth pretensioner activation.
Innovation Solution
A protect cover with a side wall portion is integrated along the side surface of the locking base, featuring a cut where the side wall is not present over the pawl's movable region, and a ceiling portion with securing holes, to prevent contact between the locking base and the base frame, reducing resistance during pretensioner activation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the spool is allowed to rotate freely in the base frame, then webbing retraction is smooth, but the locking base contacts the base frame when decentered, increasing resistance
Solution Approach 1:
A protect cover is introduced as an intermediary component between the locking base and the base frame. This protect cover includes a side wall portion that extends along the side surface of the locking base, preventing direct contact between the locking base and the base frame when the spool becomes decentered during high-load operations or pretensioner activation.
2Volume of moving object
If the locking base is positioned close to the base frame for compact design, then device size is reduced, but contact occurs during spool movement, increasing resistance
Solution Approach 1:
The protect cover serves as a protective intermediary that allows the locking base to be positioned close to the base frame for compact design while preventing harmful contact. The side wall portion of the protect cover extends to prevent the locking base from contacting the base frame during spool movement, thus eliminating the harmful friction and resistance.
Solution Approach 2:
The protect cover is installed beforehand to prevent contact between the locking base and base frame. This protective structure is in place before any decentering occurs, cushioning against potential harmful contact and ensuring smooth operation during high-load conditions or pretensioner activation.
Data Source
Figure 1
Figure 2
Figure 3(A)~3(B)
AI summary
In order to provide a seat belt retractor and a seat belt apparatus in which contact between a locking base and a base frame can be suppressed, a seat belt retractor includes a spool (2) that retracts a webbing restraining an occupant, a base frame (3) that accommodates the spool (2) while allowing the spool (2) to rotate, and a lock mechanism (4) regulating rotation of the spool (2). The lock mechanism (4) includes a locking base (41) disposed at an end portion of the spool (2), an opening (31) that is formed in the base frame (3) and allows the locking base (41) to be inserted therethrough, engagement teeth (32) formed at an inner edge of the opening (31), and a pawl (42) that is disposed radially outwardly movable relative to the locking base (41) and engageable with the engagement teeth (32). The lock mechanism (4) further includes a protect cover (43) that is attached to the locking base (41) and includes a side wall portion (43b) disposed along a side surface portion of the locking base (41).