GB2317859A - Retractor reel for a safety belt - Google Patents

Abstract

A retractor reel for a safety-belt comprises a spool 6 on which the safety-belt is wound. A spring 15 biasses the spool 6 to reel-in the safety-belt during normal wear, and the spool is locked when an accident occurs. A rotor 18 is connected to the spool 6 and defines arcuate flow passages which extend radially outwards toward outlets 24 formed in the housing 10. The outlets to the flow passages are arranged tangentially to the outer periphery of the rotor 18 such that, in response to an accident, gas generated from the pyrotechnic charge 27 causes the rotor 18 to rotate, thus pre-tensioning the safety-belt.

Description

DESCRIPTION OF INVENTION "INPROVEMENTS IN OR RELATING TO A RETRACTOR REEL" THE PRESENT INVENTION relates to a retractor reel and more particularly relates to a retractor reel intended for use with a safety-belt in a motor vehicle such as a motor car.

It has been proposed previously to provide a retractor reel for use with a safety belt in a motor car with a pre-tensioner mechanism, that is to say a mechanism which is adapted to apply a preliminary tension to the safety-belt when an accident occurs.

The advantage of providing the retractor with a pre-tensioner is that, when accident occurs, the safetybelt is drawn tightly across the chest and lap of the occupant of the vehicle, to avoid unnecessary forward movement of the occupant of the vehicle.

Some prior proposals utilise rotary fluid motors.

For example, GB-A-1,587,460 discloses an arrangement in which a paddle wheel is connected to one end of the spool of the retractor, on which the safety-belt is wound, and gas is directed towards the paddle wheel, in the event that an accident arises, in order to rotate the paddle wheel and the spool, thus tensioning the belt. DE-A-2,814,487 discloses another arrangement in which a motor is provided at the end of the spool of a retractor. The motor comprises a housing defining a circular cross-section chamber which receives a rotatable element. The rotatable element is provided with scraper elements which are resiliently biassed outwardly to engage the inner wall of the chamber. A gas is supplied to one part of the chamber causing the element to rotate, thus applying a tension to the safety-belt.

The prior art arrangements are relatively complex in operation and relatively expensive to manufacture.

According to this invention there is provided a retractor reel for a safety-belt, the retractor reel comprising means supporting a spool, a safety-belt to be wound on to the spool, resilient means adapted to bias the spool to reel in the safety-belt on to the spool, and means responsive to an indication that an accident is occurring to lock the spool to prevent the withdrawal of the safetybelt from the spool, there being a rotatable element adapted to co-rotate with the spool, the element defining at least one flow passage for gas, the flow passage terminating with an outlet spaced radially from the axis of rotation of the element and having a substantial tangential component, there being gas supplying means adapted to supply gas to the said flow passage, and means responsive to the occurrence of an indication that an accident is occurring to activate the gas supplying means.

Preferably the said element is mounted directly for rotation with the spool.

Conveniently the said element defines a plurality of flow passages.

Advantageously the or each flow passage extends from a chamber which is substantially aligned with the axis of rotation of the element.

Preferably said cavity is located adjacent an opening defined by a projecting collar, the gas supply means being connected to said opening by means of a seal.

Conveniently the or each flow passage is of reducing cross-section towards said outlet.

In a preferred embodiment the gas generator comprises a pyrotechnic device, but alternatively it may comprise a source of compressed gas.

The present invention seeks to provide an improved retractor reel.

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 perspective view of part of a retractor reel in accordance with the invention, the outer housing of the retractor reel being removed for the sake of clarity of illustration.

FIGURE 2 is a sectional view of part of the arrangement of Figure 1, and FIGURE 3 is an elevational perspective view of the part of the arrangement of Figure 1 as illustrated in Figure 2, with parts shown in phantom.

Referring initially to Figure 1, a retractor mechanism for a safety-belt comprises a substantially "U"shaped metal frame 1 having a base 2 and two forwardly extending side arms 3,4. The base 2 is provided with a plurality of apertures 5 to enable the frame to be secured in position.

Extending between the two forwardly extending side arms 3,4 is a spool 6 (shown in Figure 2) which has wound on it a reel 7 of safety-belt 8.

One side arm 3 carries a housing 9 which contains a conventional locking mechanism adapted to lock the spool 6 in the event that an accident arises, to prevent safety-belt being withdrawn from the reel on the spool.

Such locking mechanisms are conventional and thus the locking mechanism will not be described in detail here.

The forwardly extending side arm 4 carries, on its outer surface, a housing 10.

The housing 10, as can be seen more clearly in Figure 2, receives a trunnion 11, which forms part of the spool 6, the trunnion 11 passing through an aperture 12 formed in the forwardly extending wall 4. The trunnion engages one end 14 of a helical spring 15, the other end of which is connected to an outer wall 16, forming part of the housing 10. The spring 15 provides a torsional force tending to rotate the spool 6 to retract the safety-belt 8 on to the spool 6 to form the reel 7.

An end portion 17 of the trunnion 11 extends beyond the spring 15 and engages securely part of a rotor element 18. The rotor element 18, as can be seen more clearly from Figure 3, is of circular form and has a central axial opening, defined by an upstanding collar 19, which communicates with a central chamber 20 which in turn extends to three substantially radially outwardly directed flow passages 21.

Each of the flow passages 21 is of arcuate form, and of gradually reducing width, as seen in Figure 3 and gradually reducing depth as seen in Figure 2. Thus, each flow passage is of reducing cross-section. Each flow passage 21 terminates with an outlet aperture 22 located at the outer periphery of the element 18, each outlet 22 being directed, relative to the outer periphery of the element 18, with a substantial tangential component.

The side wall 23 of the housing 10 is provided with a plurality of apertures 24 which are substantially aligned with the outlets 18.

The housing 10 covers the element 18 and carries a pyrotechnic charge 27. The pyrotechnic charge is aligned with the opening defined by the upstanding collar 19 and a seal 28 is located between the pyrotechnic charge and the collar 19 to form a substantially gas-tight seal. A squib 25 is associated with the pyrotechnic charge 27 adapted to ignite the pyrotechnic charge. As can be seen in Figure 1, the squib 25 is associated with a crash sensor 26, such as an accelerometer, although an impact sensor may be used.

In operation of the retractor reel illustrated in Figures 1 to 3, in the event that an accident arises, the crash sensor 26 will generate a signal which is supplied to the squib 25. The squib 25 activates the pyrotechnic charge 27, and a substantial quantity of gas is generated.

The gas is injected into the chamber 20 defined by the element 18 and subsequently flows along the arcuate radially outwardly extending passages 21. The gas is ejected through the outlet apertures 22, and because of the formation of the outlet apertures 22, the gas is directed away from the element 18 with a substantial tangential component. Because the pressure supplied by the pyrotechnic charge and the reducing cross-section of the flow passages, the gas is ejected from the outlet apertures 22 with a substantial velocity. The gas escapes from the housing 10 through the apertures 24.

Consequently, the element 18 rotates.

Because the element 18 is connected to the end part 17 of the trunnion 11 that is formed integrally with the spool 6, the element 18 rotates with the spool 6, and consequently as the element 18 is driven rotationally, so the spool 6 is driven, thus retracting safety-belt 8 on to the reel 7 of safety-belt.

It is to be appreciated that in ordinary use of the safety-belt, the element 18 will co-rotate with the spool 6, rotating in one sense as the safety-belt is paid out from the reel 7 and rotating in the opposite sense as the safety-belt is withdrawn on to the reel 7 under the torsional force provided by the spring 15.

It is to be appreciated that the element 18 may be made of any appropriate material, and consequently need not be expensive. For example, the element may be made from a relatively cheap alloy or even from a thermoset plastic.

It is to be appreciated that whilst the invention has been described with reference to one specific embodiment, various modifications could be effected without departing from the scope of the invention. For example, instead of using a pyrotechnic charge to generate gas, a source of compressed gas could be utilised. Instead of utilising a plurality of air-flow passages, only one airflow passage need be utilised. Instead of the element defining the flow passages being connected directly to the spool 6, the element could be connected for co-rotation of the spool by means of a gear arrangement.

Claims (9)

CLAIMS:

1. A retractor reel for a safety-belt, the retractor reel comprising means supporting a spool, a safety-belt to be wound on to the spool, resilient means adapted to bias the spool to reel in the safety-belt on to the spool, and means responsive to an indication that an accident is occurring to lock the spool to prevent the withdrawal of the safety-belt from the spool, there being a rotatable element adapted to co-rotate with the spool, the element defining at least one flow passage for gas, the flow passage terminating with an outlet spaced radially from the axis of rotation of the element and having a substantial tangential component, there being gas supplying means adapted to supply gas to the said flow passage, and means responsive to the occurrence of an indication that an accident is occurring to activate the gas supplying means.

2. A retractor according to Claim 1 wherein the said element is mounted directly for rotation with the spool.

3. A retractor according to Claim 1 or 2 wherein the said element defines a plurality of flow passages.

4. A retractor according to any one of the preceding Claims wherein the or each flow passage extends from a chamber which is substantially aligned with the axis of rotation of the element.

5. A retractor according to Claim 4 wherein said cavity is located adjacent an opening defined by a projecting collar, the gas supply means being connected to said opening by means of a seal.

6. A retractor according to any one of the preceding Claims wherein the or each flow passage is of reducing cross-section towards said outlet.

7. A retractor according to any one of the preceding Claims wherein the gas generator comprises a pyrotechnic device.

8. A retractor according to any one of Claims 1 to 6 wherein the gas generator comprises a source of compressed gas.

8. A retractor for a safety-belt substantially as herein described with reference to and as shown in the accompanying drawings.

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