GB2244203A

GB2244203A - Buckle pretensioner for seatbelts

Info

Publication number: GB2244203A
Application number: GB9108609A
Authority: GB
Inventors: Muneo Nishizawa
Original assignee: Takata Corp
Current assignee: Takata Corp
Priority date: 1990-04-23
Filing date: 1991-04-22
Publication date: 1991-11-27
Also published as: GB9108609D0; DE4113094A1; DE9104917U1; FR2661137A1; JPH045148A; KR910018246A; CA2040935A1

Abstract

A buckle pretensioner for applying pretension to a vehicle restraining belt webbing by pulling a buckle B to which the restraint belt webbing is attached in a direction of pretension the restraint belt includes a buckle webbing W having one end connected to the buckle and its other end connected to a take-up device 3 for pulling the buckle webbing such as to move the buckle in the direction that pretensions the restraint belt. The take-up device includes a detent device 22, 23 for preventing the buckle from moving in the opposite direction and releasing the pretension. A guide device 11, 12 is provided along the path of the buckle webbing for changing the direction of the buckle webbing along its path between the buckle and the take-up means. The change in direction of the buckle webbing permits the take-up device to be installed in dead space in the vehicle, such as under a seat. The actuating device 4 for the pretensioning reel may be a known explosive piston/ cylinder device acting on a cable wound around the reel 32. <IMAGE>

Description

1 X 2::E --1= -cl:2 C) Buckle Pretensioner This invention relates to a

seat belt apparatus and, more particularly, to a buckle pretensioner which pulls in a buckle stay of a seat belt apparatus to remove slack from a seat belt.

A seat belt apparatus installed in an automotive vehicle for the purpose of restraining the body of a passenger in a seat is provided with a pretensioner actuated in the event of an emergency to tension the belt and remove slack. As long as a pretensioner is capable of removing the slack in the belt webbing of a seat belt apparatus, the pretentioner may be installed at any desired location. In three-point type continuous webbings ordinarily used, it has recently been verified that a system which tensions the buckle side is effective in order to apply pretention to both the shoulder belt and lap belt of the three-point type continuous webbing.

Accordingly, a pretensioner which tensions a buckle stay has been proposed as disclosed, for example, in the specifications of Japanese Patent Application laid-Open (KOKAI) Nos. 61-241234 and 1164651.

Though these examples of the prior art are functionally effective, all of them employ arrangements which require a rigid guide mechanism for guiding the buckle stay in the pull-in direction on the inner side of the seat for the purpose of rendering the buckle independent. Since this mechanism occupies a fairly large amount of useful space on the seat side, the examples of the prior art are not necessarily effective in terms of design, because they diminish the degree of freedom with regard to vehicle engineering. Another arrangement has been proposed [for example, see the specifications of Japanese Utility 5 Model Publication (KOKOKU) Nos. 54-44337 and 56-12136] as a means for holding the buckle stay in an independent state without taking up space on the inner side of the seat. Specifically, a buckle is supported on a boot, the base end of the boot is supported on the side of the seat cushion, and the webbing secured to the buckle is passed through the interior of the boot and connected to a retractor or to a fixed point.

If it were possible to supply a pretensioner to the webbing of a buckle having such an independent mechanism, then it would be possible to realiz-e a practical buckle pretensioner devoid of the aforesaid difficulty in which the above- mentioned useful space is occupied.

The present invention has been proposed in view of the foregoing circumstances, and its object is to provide a buckle pretensioner capable of being applied to the conventional independent type buckle, wherein the position of installation is capable of being selected at will.

According to the present invention, the foregoing object is attained by providing a buckle pretensioner for applying pretension to a vehicle restraint webbing by pulling a buckle webbing connected to a buckle in a direction to pretension the restraint webbing. The invention is characterized in that the other end of the buckle webbing is connected to a take-up device for pulling he webbing and thereby moving the buckle in a direction to tighten the restraint belt webbing.

The take-up device includes a detent arrangement to prevent the buckle from moving in the opposite i i 1 direction and releasing the pretension. A guide device is provided along the path of the buckle webbing for changing the direction of the buckle webbing along its path between he buckle and the take-up device.

In the buckle pretensioner of the present invention, the buckle webbing is introduced to the take-up means after having its direction changed by the guide device, and the buckle is pulled down by the operation of the take-up means, thereby applying pretension to the seat belt. Release of the applied pretension is prevented by the detent mechanism of the take-up device.

other features and advantages of the present invention will be apparent from the following description of embodiments taken in conjunction with the accompanying drawings, in which like reference characters designate the same or similar parts throughout the figures thereof.

Fig. 1 is a perspective view showing an embodiment of the present invention; Fig. 2 is a perspective view showing, in enlarged form, a buckle pretensioner as well as the positional relationship of portions associated therewith; Fig. 3 is a sectional view showing the details of a pull-in mechanism of the buckle pretensioner; Figs. 4A and 4B illustrate the details of a shaft of the buckle pretensioner and portions associated therewith, in which Fig. 4A is a side view and Fig. 4B a sectional taken along line 4A-4A; and Figs. 5A and 5B are side sectional views useful in describing the operation of the apparatus.

An embodiment of the present invention will now be described in detail with reference to the accompanying drawings.

Fig. 1 is a perspective view illustrating a seat belt apparatus to which the buckle pretensioner according to the embodiment of the invention is applied.

The buckle pretensioner in this seat belt apparatus is disposed beneath a seat and is connected to a buckle B installed on the inner side of the seat, and the buckle pretensioner is adapted to apply pretension to a shoulder belt S and a lap belt L by pulling a webbing W. The webbing W is connected, via guiding means 1 which changes the stretching direction of the webbing, to take-up means 3 having a detent mechanism 2. In Fig. 1, numeral 4 denotes a pull-in mechanism of the take-up means 3, and reference characters A, R and T represent a through-anchor, a retractor and a through-tongue T.

Fig. 2 is a perspective view showing, in enlarged form, a buckle pretensioner as well as the positional relationship of portions associated therewith. Though all of the components in Fig. 2 are shown to be disposed in a manner opposite that depicted in Fig. 1, the arrangement is substantially the same.

The buckle B is connected to the guiding means 1 via a boot B1 whose upper end is integrally joined with the lower part of the buckle. The guiding means 1 is attached to a seat or vehicle body by bolts or the like so as to be free to tilt back and forth through a prescribed angular range with respect to the seat. The webbing W, the upper end of which is fixed to the lower part of the buckle B, extends to the take-up means 3 through the interior of the boot B1 and via a hole 11 provided in the guiding means 1. The base end of the webbing W is secured to and wound about a shaft 32, the 1 i 1 1 details of which will be described later. A cylindrical guide bar 12 for smoothly guiding the bent portion of the webbing W is disposed on the upper edge of the hole 11 in the guiding means 1. The take-up means 3 is equipped with the shaft 32 whose two ends are freely rotatably supported on a bracket-shaped base 31. One end of the shaft 32 is formed to be square. and a ratchet wheel 21 constituting a detent mechanism is attached to this square end of the shaft. A ratchet pawl 22 freely rotatably supported on the base 31 is biased by a spring 23 so as to engage with teeth on the circumference of the ratchet wheel 21. The other end of the shaft 32 also is formed to be square and has a pulley 41, which constitutes a pull-in mechanism 4, attached thereto.

Fig. 3 is a sectional view showing the details of the pull-in mechanism, and Figs. 4A and 4B illustrate the details of the shaft and portions associated therewith. in which Fig. 4A is a side view and Fig. 4B a sectional view taken along line 4B-4B.

As illustrated in Figs. 3, 4A and 4B, a wire 42 is wound about the pulley 41 in a circumferential groove thereof. One end of the wire 42 is fixed to the pulley 41 at a fastener tab portion 43 formed by cutting and bending into the groove a portion of the flange of the pulley 41. A block 44 which prevents the wire from slipping off is attached to the tip of the portion 43. The other end of the wire 42 is connected to a piston 45 of the pull-in mechanism 4, and the piston 45 is free to slide inside a cylinder 46. Attached to one end of the cylinder 46 is an actuating means 47 which produces an operating gas by burning of an explosive mixture 48 filling its interior. The actuating means 47 and the cylinder 46 are interconnected by a gas conduit 49.

The shaft 32 has a slit 33 through which the webbing W, which extends in the axial direction of the shaft, is passed. The base end of the webbing W is folded back onto itself and sewn to form a looped portion through which a webbing stopper shaft 34 is inserted. Accordingly, the webbing W, which is secured fast to the shaft 32 by the webbing stopper shaft 34, is passed through the slit 33 and led out to the exterior of the shaft 32.

Fig. 5A illustrates the buckle pretensioner in the non-operating state, in which the boot B1 is extended and the buckle B is held in an independent state. Under these conditions, the webbing W also is in the extended state and is capable of being wound up at all times in the direction of arrow X in Fig. 5A. When an acceleration sensor (not shown) senses emergency deceleration of the vehicle in excess of a predetermined value under these circumstances, the sensor transmits an electrical signal to the actuating means 47 of the pull-in mechanism 4 shown in Fig. 3, thereby igniting and burning the explosive mixture 48. Owing to the combustion gas produced, the piston 45 is moved rightward with respect to (Fig. 3) at high speed, as a result of which the wire 42 is pulled in the same direction to rotate the pulley 41 clockwise. Upon this rotational motion of the pulley 41, the shaft 32 is rotated clockwise (See Fig. 5B whereby the webbing W is wound up on the shaft 32. This pulls down the throughtongue T along with the buckle B and, at the same time, rotates the ratchet wheel 21 while pushing out the ratchet pawl 22 against the biasing force produced by the biasing spring 23. As a result, pretension is applied to the shoulder belt S and lap belt L shown in Fig. 1. At the pull-in operation of the webbing W, the bent portion of the webbing W is pulled in smoothly while being guided by the guide bar 12. After the webbing W is pulled in rapidly in this manner, an inertial force acting upon the body of the passenger attempts to pull out the shoulder belt S and lap belt 1 i i i i g L. However, the inertial force produces a restoring action which pulls back the webbing in buckle B, so that the shaft 32 and ratchet wheel 21 attached to the shaft 32 are caused to rotate counter-clockwise, as indicated by arrow Y in Fig. 5B. This rotation of the ratchet wheel 21 has the effect of allowing the ratchet pawl 22 to be pushed in toward the axis of the ratchet wheel by the biasing force of biasing spring 23 so as to engage a tooth of the ratchet whee.'11.. This prevents further return of the shaft 22 in the direction of arrow Y as a result of the tension acting upon shoulder belt S and lap belt L.

Thus, with the apparatus of the prese.-t invention, guidance in the pulling (descending) direction of the webbing W on the side of the buckle B is performed by the boot B1, and therefore a special mechanism for supporting the buckle B is not required. Since the guiding means 1 for changing the direction of the webbing W along a path between the buckle B and the take-up means 3 is provided, the pretensioner can be arranged in the space beneath the seat, which is dead space within the vehicle. In addition, effective pretension can be applied to the shoulder belt S and lap belt L by a simple mechanism. Though the present invention has been described in detail based upon the foregoing embodiment, the invention is not limited to these embodiments but can be modified in various ways within the scope of the claims. 30 By way of example, a compression coil spring or a torsion coil spring can be used instead of the explosive mixture mentioned above to pull the webbing W.

claims 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 1.

A buckle pretensioner for applying pretension to a vehicle restraint belt webbing by pulling a buckle to which the restraint belt webbing is attached in a direction to pretension the restraint belt and including a buckle webbing having one end connected to the buckle characterized in that the other end of the buckle webbing is connected to a take-up means for pulling the buckle webbing such as to move the buckle in said direction and including detent means for preventing the buckle from moving in the opposite direction and releasing the pretension and in that guide means is provided along the path of the buckle webbing for changing the direction of the buckle webbing along its path between the buckle and the take-up means.

2. A buckle pretensioner substantially as herein described with reference to and as illustrated in the accompanying drawings.

Published 1991 at 7be Patent Office, Concept Houm Cardiff Road. Newport, Gwent NP9 I RH. Further copies may be obtained from Sales Branch, Unit 6. Nine Mile Point. Cwmfelinfach, Cross Keys. Newport, NPI 7HZ. Printed by Multiplex techniques lid, St Mary Cray, Kent.

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