Chairs and seats – Body or occupant restraint or confinement – Safety belt or harness; e.g. – lap belt or shoulder harness
Reexamination Certificate
2000-11-22
2001-09-04
Barfield, Anthony D. (Department: 3636)
Chairs and seats
Body or occupant restraint or confinement
Safety belt or harness; e.g., lap belt or shoulder harness
C297S216130, C242S384400
Reexamination Certificate
active
06283553
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to seat belt retractors and, more particularly, to seat belt retractors having universal acceleration sensors for use in reclinable seat backs.
BACKGROUND OF THE INVENTION
There are regulations currently in place in the U.S. that mandate certain retractor locking requirements which specify that acceleration sensors must be operable to lock the retractor at either one of two conditions. The first condition requires that at threshold accelerations of 0.7 g's, the sensor should cause locking of the retractor in any of three mutually-perpendicular planes. In these planes, the retractor must also lock at the specified acceleration when tilted at 45° increments to a range of 180° in the plane.
Automobiles are manufactured with their seat backs at a nominal design and installed position from which they can be shifted and tilted forwardly and rearwardly to respective maximum forward and rearward inclinations of the seat backs. Accordingly, §209 specifies that if the first condition is not met by the seat back retractor, the other alternative condition that must be satisfied is that the retractor lock when tilted forward or rearward 45° from the design position of the seat back. Where the retractor has the previously-described types of inertia members that may not satisfy the first condition of §209 in properly detecting vertically aligned accelerations, the second condition where locking must be present at 45° from the design position of the seat back must be established.
One of the difficulties in providing a commercially successful, inclinable retractor being shifted with a changing of the seat inclination is maintaining the sensitivity of the retractor locking mechanism, which typically means keeping the gap between the pawl and ratchet teeth at a constant distance. This is difficult because the inertia weight is often carried in a pivotal support and shifts relative to the pawl, which is mounted on a stationary support. The retractor locking mechanism's sensitivity should be substantially the same when the inertia member is at the nominal seat back position or when swung through almost 45° as when closely adjacent the rearward inclination position.
While there have been a number of prior art acceleration universal sensors designed for use in reclinable seat backs, many of these use inertia members that will not shift properly to sense accelerations in an aligned vertical plane. Further, none of these prior art universal inertia sensors successfully meet the specifications that require locking of the retractor at specified angular range of 45° its position at installation, i.e., its designed position.
SUMMARY OF THE INVENTION
In accordance with the present invention, a retractor may be mounted on an inclinable seat back; and the retractor locks at specified forward and rearward inclinations. More specifically, the retractor incorporates a universal acceleration sensor that compensates for different seat back inclinations so that it does not lock until a threshold vehicle acceleration condition is detected, and so that it will lock regardless of the sensed acceleration when the seat back and retractor are or were shifted or specified inclinations forward and rearward from the seat back inclined designed position. In this manner, the vehicle sensitive retractor herein is particularly tailored to meet automotive specifications that require retractor locking at specified angular inclinations on either side of the seat back design position.
Typically, prior seat belt retractors having universal sensors typically allow for equal inclinations from one side to the other of a vertical plane such that, unlike the present retractor, they are not specifically tailored to ensure locking at specific angles forward and rearward from a designed and installed position of the seat back. The design and installed inclined position of the seat back is the inclined position at which it comes delivered from the manufacturer, e.g. 18.5° from vertical. For different manufacturers or vehicles, the retractor is designed to be operated at a specific installed position that is predetermined and known, usually vertical when mounted on a pillar or the like or inclined to the vertical when mounted on a seat. The particular specification at hand requires that the retractor be locked at 45° forward and rearward from an inclined design position such that where the design position is at 18.5°, the retractor must be locked at 63.5° inclined rearwardly from the vertical.
In one form of the present invention, the vehicle sensitive retractor herein includes an inertia sensor that has a pivotally mounted universal support that is biased to remain substantially vertical as the seat back is tilted forwardly and rearwardly on either side of the design position. Stops engage the support to stop pivoting of the support when engaged therewith. An actuator mechanism locks the retractor reel either by operation of the inertia member, or when the retractor is reclined to a predetermined rearward inclination position. The rearward inclination position is designed so that it is at an angular spacing from the designed and installed position of the seat back that substantially corresponds to that set forth in the previously-described retractor locking specifications. As the seat back and retractor thereon are pivoted downwardly from the inclined design position, a distal projection on the actuating mechanism locks the retractor reel either by operation of the inertia member, or when the retractor is reclined to a predetermined rearward inclination position. The rearward inclination position is designed so that it is at an angular spacing from the designed and installed position of the seat back that substantially corresponds to that set forth in the previously-described retractor locking specifications. As the seat back and retractor thereon are pivoted downwardly from the inclined design position, a distal projection on the actuating mechanism causes a locking of the retractor.
The support engages the other stop when the retractor and seat back are shifted forwardly of the design position to a predetermined forward inclination position. At this position, the actuator mechanism will not lock the retractor until the inertia member senses at least a 0.7 g acceleration. As previously mentioned, the relevant retractor locking specifications mandate locking at a predetermined angular spacing forward of the design position, as well. Once the support hits the other stop, upon continued pivoting of the retractor past this point towards the vertical and then inclined back on the other side of the vertical, the retractor acts like a normal retractor so that the continued pivoting causes the inertia member to become less stable and more prone to actuation as the support and inertia member now pivot with the retractor. The particular inertia member will become operable as by toppling over where a standing man kind of inertia member is utilized at a predetermined amount of pivoting thereof. The position of the forward stop is predetermined and the inertia member is chosen so that the amount of pivoting before it becomes operable will be well within the forward limit set by the retractor locking specifications. And because this limit will generally be on the side of the vertical beyond which the seat back will not be pivoted, it is acceptable to rely on the inertia member to operate the actuating mechanism for locking the retractor as sensitivity variances caused by pivoting of the inertia member and support will not be of a concern.
On the other hand, sensitivity is an important issue on the side of the vertical where the seat back will be used and pivoted between different positions. On this operative side, it is important that the inertia sensor used with the retractor maintain substantially the same sensitivity to accelerations throughout substantially the entire range of seat back inclinations. In this regard, preferably the stops are arranged so to correspond to the forward the rearward
Anderson Erick Michael
Grabowski Richard M.
Barfield Anthony D.
Fitch Even Tabin & Flannery
Takata Seat Belts Inc.
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