PRETENSIONER

Abstract: A pretensioner fitting arrangement comprising an arming bracket (3) having a flange (16) operable to arm the pretensioner when the bracket is fitted, and having means for limiting access to the means (2) by which the pretensioner is fitted to the vehicle. The arming bracket (3) is secured to the pretensioner by a screw having two head parts (4, 5), coaxial one with the other but arranged so that one head part (5) is covered by a sealing ring (15), the two head parts being connected together by a section which is adapted to break when a torque of a predetermined level is applied to it. Heads (4, 5) may be coloured or shaped differently. The invention allows arming of the pretensioner after it is installed in the car and prevents the removal of the pretensioner in an armed state. It also makes it extremely difficult for any unauthorised dealer to fit second hand pretensioners and provides a visual indication to the vehicle owner or inspector if this has happened.

Description: PRETENSIONER DESCRIPTION The present invention relates to a pretensioner for a vehicle safety restraint and particularly to a tamper-proof fitting therefor. Modern pretensioners operate at very high levels of force to rapidly take up the slack in a safety belt in a crash situation. The pretensioner may be sited at the retractor end of the belt and is connected to rapidly rewind the belt webbing reel. The force required is generated either mechanically by a powerful pre-stressed spring or by pyrotechnic means and an armed pretensioner requires careful handling and safety procedures must be observed. The pretensioner is supplied to the vehicle manufacturer or authosied fitter in a disarmed state so that it is safe to transport. It is only armed when it has been correctly fitted in the vehicle. However, a problem arises if the pretensioner is removed from the vehicle after fitting. In this case the pretensioner is armed and will constitute a safety hazard in handling and transport. Furthermore, unscrupulous dealers and fitters may be tempted to dispose of these second hand pretensioners to fit in other vehicles. This is undesirable because they will not have been checked by the manufacturer or other authorised and trained people. They may then constitute a safety hazard or may fail to operate correctly in a crash situation. In addition known pretensioner fitting and arming arrangements are complicated, expensive and difficult to fit. According to the present invention there is provided a pretensioner fitting arrangement comprising an arming bracket having a flange operable to arm the pretensioner when the bracket is fitted, and having means for limiting access to the means by which the pretensioner is fitted to the vehicle, a screw having two head parts, coaxial one with the other but arranged so that one had part is covered, for example by a sealing ring, the two head parts being connected together by a section which is adapted to break when a torque of a predetermined level is aplied to it. At least one and preferably both of the screw head parts may be hexagonal in shape. According to a preferred embodiment of the present invention, the sealing ring or other screw covering part may be colour coded to identify the fitter. Alternatively different shaped heads may be used for the same purpose. If a bright colour is used for the sealing ring, it will be particularly easily evident whether or not the pretensioner has been tampered with by any unauthorised person. The invention allows arming of the pretensioner after it is installed in the car and prevents the removal of the pretensioner in an armed state. It also makes it extremely difficult for any unauthorised dealer to fit second hand pretensioners and provides a visual indication to the vehicle owner or inspector if this has happened. For a better understanding of the invention and to show how the same may be carried into effect, reference will now be made to the accompanying drawings in which: Figure 1 is a partially exploded, perspective view showing how a pretensioner is fitted in a vehicle using a fitting arrangement according to a first embodiment of the present invention. Figure 2 illustrates the components of Figure 1 in an assembled state. Figure 3 illustrates a second embodiment of the invention in a partially exploded, perspective view. Figure 4 shows the components of Figure 2in an assembled state. In all Figures a pretensioner tube 1 is attached to a retractor assembly 6 which is fixed to a B-pillar 7 of the side of a vehicle. An arming bracket according to the invention is shown at 3. The forward direction of the vehicle is indicated by arrow F. Seat belt webbing 8 is wound on the retractor 6 spool and exits the retractor vertically parallel to the B-pillar 7. A recess 9 is provided in the B-pillar 7 into which the retractor 6 and pretensioner 1 fits. The retractor 6 is fixed to the B-pillar 7 by a relatively large diameter screw 2 which secures through a hole 10 in the retractor frame plate 11 and a hole 12 in the B-pillar 7. The arming bracket 3 is then placed adjacent to the retractor 6 so that covering flange 13 overlaps, and preferably completely obscures the head of the fixing screw 2. This makes it very difficult for the pretensioner - retractor assembly to be dismounted from the vehicle unless the arming bracket 3 is first removed and once arming bracket 3 is removed, the pretensioner is automatically disarmed since arm 16 disengages from the pretensioner. The arming bracket 3 is secured to the retractor frame plate 11 by an arming screw of a special construction. The screw 4 has two heads 4 and 5, coaxial with each other and separated by a relatively weak stem portion 14. The inner head part 5 is covered by a sealing ring 15. Figure 2 shows clearly how these parts fit together in the assembled state in the recess 9 in the B-pillar 7. As the screw 4 is tightened into its fitting, the torque causes the stem connecting portion 4 between the two heads 4 and 5 shears, thus detaching the outer head 4. The inner head 5 is surrounded by sealing ring 15 and thus protected from unauthorised tampering since the head is not easily exposed for engagement with a spanner or other turning tool . Even if the arming bracket is removed, the pretensioner will be disarmed and cannot be rearmed for unauthorised installation in another vehicle, unless the arming bracket is re- attached. This can only be done (without detection) by an authorised dealer with access to a replacement arming screw with double heads and sealing ring intact. Figures 3 and 4 show an alternative embodiment of the invention. Like parts are denoted by like reference numerals. In this embodiment three retractor fixing screws 2 are used instead of one, and the pretensioner - retractor arrangement is attached using an additional fixing plate 17. As can be seen in Figure 4, only one of the fixing screws 2 is covered by the arming bracket 3 in the fixing position, but this is sufficient to prevent unauthorised tampering with the pretensioner. It can be clearly seen in Figure 4 that the lever 16 of the arming bracket fits into a recess in the side of the pretensioner to arm it .

Claims: CLAIMS 1. A pretensioner fitting arrangement comprising an arming bracket having a flange operable to arm the pretensioner when the bracket is fitted, and having means for limiting access to the means by which the pretensioner is fitted to the vehicle, a screw having two head parts, coaxial one with the other but arranged so that one head part is covered, the two head parts being connected together by a section which is adapted to break when a torque of a predetermined level is applied to it . 2. A pretensioner fitting arrangement according to claim 1, wherein said one head part is covered by a sealing ring. 3. A pretensioner fitting arrangement according to claim 1 or 2 , wherein at least one of the screw head parts is hexagonal. 4. A pretensioner fitting arrangement according to claim 3, wherein both of the screw head parts are hexagonal. 5. A pretensioner fitting according to claim 1, 2 or 3, wherein the screw covering part is colour coded. 6. A pretensioner fitting arrangement according to claims 1 or 2 , wherein the screw head parts are different shapes in cross section.

Inventors: COPPO FULVIO, ROMEO BONINO, COPPO, FULVIO, ROMEO, BONINO
Applicants: ALLIEDSIGNAL SISTEMI DI SICURE, COPPO FULVIO, FREEMAN JACQUELINE CAROL, ROMEO BONINO, ALLIEDSIGNAL SISTEMI DI SICUREZZA S.P.A., COPPO, FULVIO, FREEMAN, JACQUELINE, CAROL, ROMEO, BONINO
Application year: 1997
Main classification: B60R22
IPC codes: B60R22, F16B31, F16B41