GB2250418A

GB2250418A - Improvements in or relating to a seat-belt pre-tensioner

Info

Publication number: GB2250418A
Application number: GB9026340A
Authority: GB
Inventors: Lars Axelsson; Lennart Karlsson
Original assignee: Autoliv Development AB
Current assignee: Autoliv Development AB
Priority date: 1990-12-04
Filing date: 1990-12-04
Publication date: 1992-06-10
Anticipated expiration: 2010-12-04
Also published as: GB2250418B; GB9026340D0

Abstract

A safety-belt pre-tensioner arrangement incorporates a buckle 1 adapted to receive a tongue provided on a safety-belt, and a wire which has one end 2 fixed to the buckle and the other end fixed to a mounting point. The wire passes around a deflector element 3. A spring device 5 is provided to move the deflector element in the event that an accident occurs. On movement of the deflector element the buckle moves by a distance which is greater than the distance of movement of the deflector element. In the preferred embodiment, the deflector element comprises a pulley 3 pivotally mounted at the end of a spring loaded longitudinally movable arm 8. <IMAGE>

Description

DESCRIPTION OF INVENTION "Improvements in or relating to a Seat-belt Pre-tensioner" THE PRESENT INVENTION relates to a seat-belt pre-tensioner for use in a motor vehicle.

It is becoming conventional to provide a seat-belt in a motor vehicle with a pre-tensioner adapted to apply tension to the seat-belt when accident conditions are sensed. In this way the seat-belt will be tightened around a person wearing the seat-belt as the accident progresses, minimising the risk of injury to that person.

Various pre-tensioning arrangements have been proposed before and the present invention seeks to provide an improved pre-tensioner.

According to this invention there is provided a safety-belt pre-tensioner arrangement, said arrangement incorporating a buckle adapted to receive a tongue provided on a safety-belt, a wire (or equivalent) having one end fixed to the buckle and the other end fixed to a mounting point, the wire passing round a deflector element, means being provided to move the deflector element in the event that an accident occurs, the arrangement being such that upon movement of the deflector element the buckle moves by a distance which is greater than the distance of movement of the deflector element.

Preferably the means to move the deflector element comprise an energy source and an associated sensor adapted to sense an accident situation and activate the energy source.

Conveniently the energy source is a pyrotechnic energy source.

Alternatively the energy source may be a spring.

Preferably the deflector is in the form of a pulley-wheel.

Conveniently means are provided to retain the deflector substantially in the final position that it adopts when it has moved.

Preferably the retaining means comprise one or more teeth provided on means supporting the deflector and a co-operating tooth or teeth provided on a fixed support.

Advantageously the deflector comprises a roller mounted on a bracket, one arm of the bracket being provided with the tooth or teeth, that arm of the bracket being movable in an aperture formed in a support plate, that aperture defining co-operating teeth adapted to co-operate with the teeth provided on the bracket.

In order that the invention may be more readily understood, and so that further features thereof may be appreciated, the invention will now be described, by way of example, with reference to the accompanying drawings in which FIGURE 1 is a diagrammatic side view of an embodiment of the invention in an initial condition, FIGURE 2 is a corresponding view showing the arrangement after an accident has arisen, and FIGURE 3 is an enlarged view of part of the arrangement shown in Figures 1 and 2 illustrating the ratchet locking device.

Referring initially to Figure 1 of the accompanying drawings a seat-belt pre-tensioner is illustrated adapted to apply tension to a seat-belt by moving a seat-belt buckle 1. The seat-belt buckle 1 is of a conventional design, and is mounted on a wire or cable 2. The wire passes round a pulley-wheel 3 and is then anchored into an anchoring block 4. The anchoring block Lt is mounted on a support plate 5. The support plate 5 defines an aperture 6 adapted to receive a fastening bolt by means of which the support plate 5 can be mounted on the motor vehicle, or on a seat present in the vehicle.

The pulley-wheel 3 is mounted on a spindle 7 which passes through apertures provided in two arms of a "U"-shaped support bracket 8. The base of the "U"-shaped bracket 8 is mounted on a support plate 9. A rod 10 is mounted on the other side of the support plate 9, and extends axially, the rod 10 terminating in an enlarged head 11. The rod extends from the plate 9, through an aperture provided in a restraining plate 12 which is mounted on and extends perpendicularly to the support plate 5. The enlarged head 11 of the rod 10 is engaged by a retaining element 13 which is associated with a sensor 14 adapted to sense accident conditions.

A helical compression spring 15 is provided extending between the plate 9 and the plate 12.

Referring now to Figure 3 one arm 16 of the "U"-shaped bracket 8 is illustrated, showing the aperture 17 provided therein to receive the pivot for the pulley-wheel 3, the position of which is illustrated in phantom. It can be seen that the upper part of the arm 16 is provided with a plurality of serrations or teeth 18. This arm 16 of the bracket 8 is positioned to lie within an elongate oval aperture 19 which is formed in the plate 5. The aperture 19 has an upper part which is formed with teeth or serrations 20 adapted to mesh with the teeth or serrations 18 provided on the arm 15 of the bracket 8.

The illustrated arrangement is adapted to be mounted in position in a motor vehicle, with the buckle 1 located at a convenient position adJacent the hips of a person wearing a safety-belt.

When accident conditions are sensed by the sensor 14, which may contain any appropriate mechanism, the retaining element 13 is released and can move pivotally, thus becoming disengaged from the enlarged end stop 11 provided on the rod 10. The rod 10 can then move towards the left under the influence of the compression spring 15. The pulley-wheel 3 is thus moved towards the left, to the position illustrated generally in Figure 2.

Because the buckle 1 is mounted on a wire or cable 2 which surrounds the pulley 3, as the pulley-wheel moves to the left the buckle 1 moves by a distance which is greater than the distance moved by the pulley-wheel 3.

Also it is to be observed that the buckle does not only move downwardly, but is also physically moved towards the left as illustrated in Figures 1 and 2. Thus the buckle would be moved from a position adjacent the hips of a person wearing the buckle to a position more behind the hips of a person wearing the buckle. Thus the geometry of the belt relative to the person wearing it will be altered, placing the belt into a position in which the person wearing the belt is restrained with optimum efficiency and a minimum risk of injury.

It is to be understood that when the pulley-wheel 3 has moved towards the left, to the position illustrated in Figure 2, any upward force applied to the wire 2, as indicated by the arrow 21 in Figure 3 will tend to move the bracket 8 upwardly, bringing the teeth 18 on the arm 16 of the bracket 8 into mating engagement with the teeth 20 defined by the upper boundary of the oval aperture 19, thus preventing the bracket 8 from moving towards the right back to its initial position. Thus the buckle 1 is retained in its new position, as illustrated in Figure 2, until the force applied thereto during the accident has terminated.

Whilst the invention has been described with reference to one embodiment it is to be appreciated that many modifications may be effected without departing from the scope of the invention as defined by the following Claims. Whilst in the described embodiment a helical compression spring 15 is used to bias the pivot wheel 3 towards the left, any other appropriate energy source may be utilised, as may be felt to be appropriate. Whilst a pulley-wheel has been mentioned, the wire or cable from the buckle may pass over any appropriate deflector, and the deflector need not rotate although this may well be preferred. Whilst one particular retaining device has been described in the form of the co-operating teeth 18 and 20, any other appropriate retaining device may be provided, such as a ratchet arrangement including a pivotally mounted pawl adapted to engage ratchet teeth or some other equivalent device.

Claims

CLAIMS:

1. A safety-belt pre-tensioner arrangement, said arrangement incorporating a buckle adapted to receive a tongue provided on a safety-belt, a wire (or equivalent) having one end fixed to the buckle and the other end fixed to a mounting point, the wire passing round a deflector element, means being provided to move the deflector element in the event that an accident occurs, the arrangement being such that upon movement of the deflector element the buckle moves by a distance which is greater than the distance of movement of the deflector element.

2. An arrangement according to Claim 1 wherein the means to move the deflector element comprise an energy source and an associated sensor adapted to sense an accident situation and activate the energy source.

3. An arrangement according to Claim 2 wherein the energy source is a pyrotechnic energy source.

4. An arrangement according to Claim 2 wherein the energy source is a spring.

5. An arrangement according to any one of the preceding Claims wherein the deflector is in the form of a pulley-wheel.

6. An arrangement according to any one of the preceding Claims wherein means are provided to retain the deflector substantially in the final position that it adopts when it has moved.

7. An arrangement according to Claim 6 wherein the retaining means comprise one or more teeth provided on means supporting the deflector and a co-operating tooth or teeth provided on a fixed support.

8. An arrangement according to Claim 7 wherein the deflector comprises a roller mounted on a bracket, one arm of the bracket being provided with the tooth or teeth, that arm of the bracket being movable in an aperture formed in a support plate, that aperture defining co-operating teeth adapted to co-operate with the teeth provided on the bracket.

9. A safety-belt pre-tensioner arrangement substantially as herein described with reference to and as shown in the accompanying drawings.

10. Any novel feature or combination of features disclosed herein.