GB2247392A

GB2247392A - Improvements in or relating to a safety-belt pre-tensioner

Info

Publication number: GB2247392A
Application number: GB9018445A
Authority: GB
Inventors: Pascal Brodier
Original assignee: GEN ENGINEERING
Current assignee: GEN ENGINEERING
Priority date: 1990-08-22
Filing date: 1990-08-22
Publication date: 1992-03-04
Anticipated expiration: 2010-08-22
Also published as: GB9018445D0; GB2247392B

Abstract

A pre-tensioner for a vehicle safety-belt includes a device which moves an element e.g. cable 7 which is connected to the safety-belt, to apply tension to the safety-belt. A compressed helical spring 12 is mounted between a fixed point 13 and an abutment 10 connected to the element. A trigger arrangement 21, 23 retains the spring in a compressed state but releases the spring in response to a predetermined deceleration of a vehicle. The spring then moves the element 7 and applies tension to the belt. Retaining means comprising conical wedge 16 and balls 30 retain the element in the position to which is moved by the spring, the retaining means being located within the hollow centre of the helical spring. <IMAGE>

Description

DESCRIPTION OF INVENTION "Improvements in or relating to a Safety-Belt Pre-Tensioner" THE PRESENT INVENTION relates to a safety-belt pre-tensooner and more particularly to a pre-tensioner for use w-th a safety-belt in a vehicle such as a motor vehicle.

Safety-belts are provided in motor vehicles to restrain drivers and passengers n the event that an accident occurs. The primary function of a safety-belt 15 to prevent a driver or passenger travelling forwardly, relative to a vehicle, when the vehicle has been rapidly decelerated in an accident. If a safety-belt is at all slack at the moment that an accident occurs, the person restrained by the safety-belt may be injured. for example, by travellIng forwardly by a signnficant dis- trance before the safety-belt actually becomes tight anr starts to restrain that person.This can be very d s- advantageous and lead to people restrained by safetybelts colliding with the steering wheel or with the window-screen of a motor vehicle.

It has therefore been proposed previously to provide a pre-tensioner which serves to apply a tension to a safety-belt when an accident is detected, so that the person restrained by the safety-belt is held firmly in their seat as the vehicle decelerates in the accid- ent. The present invention relates to a pre-tensioner of this general type.

According to one aspect of this invention there is provided a pre-tensioner for a vehicle safety-belt incorporating a device to move an element which is directly or indirectly connected to the safety-belt, to apply a tension thereto, said device comprising a compressed helical spring mounted between a fixed point and an abutment connected to said element, a trigger arrangement, adapted to retain the spring in a compressed state, but to release the spring in response to a predetermined deceleration of the vehicle, to cause the spring to move the element thus to apply the tension to the belt, and retaining means to retain the element in the position to which it is moved by the spring, the retaining means being located within the hollow centre of the helical spring.

Preferably a cylinder is provided extending axially of the spring, the cylinder being within the spring, part of the element extending through the cylinder from the abutment and past said fixed point, the retaining means comprising a portion of the element carrying a sloping face inclined towards the fixed poInt, nt, and a movable element to co-operate with the face and which, on movement of the portion towards the fixed point becomes wedged between the sloping face and the interior of the cylinder.

Conveniently said portion defInIng the sloping face is of substantially conical form.

Preferably the said movable element consists of a ring surrounding the conical part.

Advantageously the movable element consists of one or more balls to co-operate with the conical part.

In a preferred embodiment the movable element comprises a resilient ring having balls or the like incorporated in it.

Preferably the trigger consists of a pivotted arm carrying means which engage said element, thus retaining the spring in the compressed state, the arm being restrained against pivotted movement by a member which moves to release the arm in response to a predetermined deceleration there being a rotatable ball or roller between the arm and the said member.

AccordIng to another aspect of this invention a pre-tensloner for a vehicle safety-belt incorporatlng a device to move an element which is directly or indirectly connected to the safety-belt, to impart a tension thereto, said device comprising, means to bias said element to effect movement thereof, a trIgger to retain the element, but to release the element to effect sa d movement in response to a predetermined deceleration o the vehIcle, thus applying tension to the safety-belt, the trigger consisting of a pivotted arm carrying means whIch engage said element, thus retaining the element in position, the arm being restrained against pivotted movement 5 a member which moves to release the arm in response to the predetermIned deceleratIon, there be.n- an intermediate element between the arm and the sa.d member.

Preferably the intermediate element is a ball or roller.

Advantageously the ball or roller is engaged In a recess in the arm, and a recess in said member, and is not connected to the arm or to the member.

Preferably the member is a pivotally mounted mass.

Conveniently the element forms part of or is connected to a cable which is connected to a buckle adapted to receive a tongue which is mounted on the safety-belt.

In order that the invention may be more readily understood, and so that further features thereof may be appreicated, the invention will now be described, by way of example, with reference to the accompanying drawing which is a diagrammatic side view of one embodiment of the invention.

Referring to Flgure 1 of the drawings, a pretensioner for a vehicle safety-belt comprises a mounting plate 1 having a lug 2 defining an aperture 3 which can be connected to an anchoring point. The plate may also define a second lug 4 defining a second aperture 5 again for connection to a mounting point. The various components to be described hereinafter are mounted on the mounting plate.

A pulley 5 is mounted on the mounting plate an zaire 3 passes around the pulley. One end of the wire connected to a conventional buckle 8 adapted to receive a safety-belt or the like. The wire may pass through an appropriate guide (not shown) to maIntaIn the safety-belt buckle in a predetermined position where it can receive a tongue mounted on a safety-belt.

The other end of the wire 7 is connected to a plate 10. Part of the wire passes through an aperture formed In the plate 10 and terminates with a sleeve 11 which is crimped or otherwise secured to the wire, so the plate 10 cannot move axially of the wire. The plate engages one end of a helical compression spring 12 which is initially in the compressed form, the other end of the spring 12 engaging a fixed abutment 13 which is carried by the mounting plate 1. Thus the spring 12 is tending, with reference to the accompanying drawing, to move the plate 10 towards the right.

A plug 14 is mounted on the wire in the region of the abutment 13. The plug 14 comprises a cylindrical portion 15 which is crimped to the wire to secure the plug to the wire, a conical tapering portion 16, a portion 17 defining a recess 18 and a terminal portion 19, which may again be of cylindrical form and which may again be crimped to the wire.

At least the tapering portIon 16 of the plug is retained within a metal sleeve 20 whIch is contained within the helical spring 12 and which extends from the abutment 13 to the initial position of the plate 10.

A locking mechanism IS provided which engages the plug 14 to retain the pre-tensioner apparatus in an initial condition. The locking mechanism comprises an arm 21 whIch is pivotally mounted at one end about a plot poInt 22. The arm has a downwar- y extendIng pro jest on 23 whIch is engaged withIn the recess 19 formed in the p'ug 1!'. The arm 21 terminates at a free end 22 which has a recess therein which engages an intermedIate element in the form of a ball or roller 25. The ball or roller 25 engages a co-operating recess 26 defined by a weight 27 which is mounted for pivotal movement about an upper pivot axis 28.

Surrounding the tapering portion 16 of the plug 14 is a locking element 30. The locking element is in the form of a ring which may comprise a ring of resilient material such as a 110"ring formed of rubber or some similar material. The ring may have embedded in it a plurality of steel balls or similar items. Alternatively, the locking element may itself comprise a plurality of balls which may be joined together such as beads on a necklace.

In any event the locking element 30 is so dimensioned that it just touches the interior of the sleeve 20. Should the plug move towards the right, the locking element will move down the conically tapering portion 16 towards the narrowest part (i.e. towards the position shown in the drawing), and the locking element will then slide within the sleeve 20. However, should the plug move towards the left, the locking element will engage the sleeve 20 and will thus tend to move up the conically tapering portion towards the widest part, thus deformlng the locking element 30. The locking element 30 will then become wedged firmly between the tapering Portion 16 and the interior of the sleeve 20, thus preventing further movement of the plug towards the left.

The mechanism as described above may be contanned wIthin an appropriate housing indicated at 31.

It is S to be appreciated, at this stage, that the aperture 3, which is connected to the pr-nc ?^: anchorIng point, is substantially in alignment ith the axis of the portion of the wire 7 extending between the pulley 6 and the buckle 8 when the buckle is in the operative condition.

The buckle will be used in the normal way, with a tongue present on a safety-belt being inserted into the buckle when a person is to travel in the motor vehicle fitted with the safety-belt and the associate pre-tensloner, the tongue being released from the buckle at the end of the journey.

If, during the journey, an accident situation should arise, the vehicle will decelerate and, when a predetermined limit of deceleration has been exceeded, the mass 27 will tend to pivot forwardly, towards the right, about the pivot axis 28. Movement of the mass 27 will not be impeded by the engagement of the arm 21 against the mass 27, since the engagement of the arm 21 against the mass 27 is through the intermediate member 25 which consists of a ball or a roller. Thus the mass is relatively free to move and movement will not be undesirably impeded. The mass may, if desired, be associated with a spring or other resilient means applying a bias to retain the mass in the initial position as illustrated, so that the spring or other resilIent bias has to be overcome before the mass can move to a position in which the arm 21 is released.This may prevent the apparatus triggering unintentionally. In an alternative arrangement (not shown in the drawIng), the form of the recesses in the free end of the arm 24 and in the mass 27 which receive the ball or roller 25 may be such that if the mass 27 is to pivot forwardly, the free end of the arm 21 must move downwardly against the bias imparted thereto by the action of the sprIng 12 vta the projectIon 23. Thus the deceleratIon must be sufficient so that the initial movement of the mass can move the end of the arm 24 down to release the ball or roller before the device is actually triggered.

When the mass 27 has moved forwardly, the intermediate element comprIsed by the ball or roller 25 will become disengaged from the recess 26 and also disengaged from the free end 24 of the arm 21. Once the free end of the arm 24 is no longer restrained by the intermediate member, the arm 21 will be free to pivot about the pivot axis 22. Since the projection 23 on the arm is located beneath the level of the pivot axss 22, the arm will tend to pivot upwardly about the pivot axis 22 under the bias provided by the spring 12. The spring 12 is tending to move the plate 10 towards the right, and is thus tending also to move the plug 14 towards the right. As the plug 14 moves towards the right the upwards movement of the arm 21 disengages the projection 23 from the recess 18.The spring 12 then moves the plate 10 towards the right to the position 10' illustrated in phantom. The spring is a spring of considerable strength, and thus moves to the position 10' almost regardless of the force applied to the buckle 8 by the safety-belt. It will be appreciated that during this movement of the plate to the position 10' the buckle is moved to the position Illustrated in phantom at 8'. Thus the buckle has moved downwardly and it Is to be appreciated that the buckle will have taken up any slack" in the safety-belt connected to the buckle and will have effectively tightened the safety-belt about the person wearing the safety-belt.

If any force is then applied to the buckle, that force will be transmitted to the plug through the wire 7. However, if any force is applied to the plug In this way the locking element 30, which engages the interior of the sleeve 20 and the conically tapering portion 16 of the plug 14 will tend to move up the conically tapering portion so that the locking element 30 securely wedges between the tapering portion 16 and the sleeve 20, thus retaining the plug In its positIon.

Thus, when the device operates the plug initially moves towards the right and is then prevented, by the operation of the locking element, from moving back towards the left. Thus, it is to be appreciated that the buckle 8 is moved to the position 8' and is then retained firmly in that position. Any forte applied to the buckle when in the position 8' is trans ferred to the aperture 3 which is connected to the anchoring point.

Whilst one specific embodiment has been illustrated in the drawing it will be appreciated that various modifications may be made to this embodiment without departing from the scope of the present invention.

Claims

CLAIMS:

1. A pre-tensioner for a vehicle safety-belt incorporating a device to move an element which is directly or indirectly connected to the safety-belt, to apply a tension thereto, said device comprising a compressed helical spring mounted between a fixed point and an abutment connected to said element, a trigger arrangement, adapted to retain the spring in a compressed state, but to release the spring in response to a predetermined deceleration of the vehicle, to cause the spring to move the element thus to apply the tension to the belt, and retaining means to retain the element in the position to which it is moved by the spring, the retaining means being located within the hollow centre of the helical spring.

2. A pre-tensioner according to Claim 1 wherein a cylinder is provided extending axially of the spring, the cylinder being within the spring, part of the element extending through the cylinder from the abutment and past said fixed point, the retaining means eompr-s- ing a portIon of the element carrying a sloping face i- dined towards the fixed point, and a movable element to co-operate with the face and which, on movement of the portion towards the fixed point becomes wedged between the sloping face and the interior of the cylinder.

3. A pre-tensioner according to Claim 2 wherein said portion defining the sloping face is of substantially conical form.

4. A pre-tensioner according to Cla'm 3 whereIn the said movable element consists of a ring surroundIng the conical part.

5. A pre-tensioner according to Claim 3 wherein the movable element consists of one or more balls to co-operate with the conical part.

6. A pre-tensioner according to Claim 3 wherein the movable element comprises a resilient ring having balls or the like Incorporated in it.

7. A pre-tensioner according to any one of Claims 1 to 6 wherein the trigger arrangement consists of a pivotted arm carrying means which engage said element, thus retaining the spring in the compressed state, the arm being restrained against pivoting movement by a member which moves to release the arm in response to a predetermIned deceleration, there beIng a rotatable ball or roller between the arm and the said member.

8. A pre-tensioner for a vehicle safety-belt incorporating a device to move an element which is dIrectly or indirectly connected to the safety-belt, to impart a tension thereto, said device comprising, means to bias said element to effect movement thereof, a trIgger to retain the element, but to release the el- ment to effect saId movement in response to a predeter m-ned deceleration of the vehicle, thus applyIng tension to the safety-belt, the trigger consisting of a pivotted arm carrying means which engage said element, thus retaining the element in position, the arm being restrained against pivotted movement by a member which moves to release the arm in response to the predetermined deceleration, there being an intermediate element between the arm and the said member.

9. A pre-tensioner according to Claim 8 wherein the intermediate element is a ball or roller.

10. A pre-tensioner according to Claim 7 or Claim 9 wherein the ball or roller is engaged in a recess in the arm, and a recess in said member, and is not connected to the arm or to the member.

11. A pre-tensioner according to Claim 7, 9 or 10 wherein the member is a pivotally mounted mass.

12. A pre-tensioner for a vehicle safety-belt substantially as herein described with reference to and as shown in the accompanying drawings.

12. A pre-tensioner according to any one of the preceding Claims wherein the element forms part of or is connected to a cable which is connected to a buckle adapted to receive a tongue which is mounted on the safety-belt.

13. A pre-tensioner for a vehicle safety-belt substantially as herein described with reference to and as shown in the accompanying drawings.

14. Any novel feature or combinatIon of features disclosed herein.

AMENDMENTS TO THE CLAIMS HAVE BEEN FILED AS FOLLOWS.

1. A pre-tensioner for a vehicle safety-belt incorporating a device to move an element which is directly or indirectly connected to the safety belt, to apply a tension thereto, said device comprising a compressed helical spring mounted between a fixed point and an abutment connected to said element; a trigger arrangement, adapted to retain the spring in a compressed state, but to release the spring in response to a predetermined deceleration of the vehicle, to cause the spring to move the element thus to apply the tension to the belt; a cylinder extending axially of the spring, the cylinder being within the spring, part of the element which carries a sloping face inclined towards the fixed point being located within the cylinder and retaining means to retain the element in the position to which it is moved by the spring, the retaining means being located within the hollow centre of the helical spring and comprises a movable element to co-operate with the said sloping face and which, on movement of the said part of the element towards the fixed point becomes wedged between the sloping face and the interior of the cylinder.

2. A pre-tensioner according to Claim 1 wherein said part of the element defining the sloping face is of substantially conical form.

3. A pre-tensioner according to Claim 2 wherein the said movable element consists of a ring surrounding the part of conical form.

4. A pre-tension according to Claim 2 wherein the movable element consists of one or more balls to co-operate with the part of conical form.

5. A pre-tensioner according to Claim 2 wherein the movable element comprises a resilient ring having balls or the like incorporated in it.

6. A pre-tensioner according to any one of Claims 1 to 5 wherein the trigger arrangement consists of a pivoted arm carrying means which engage said element, thus retaining the spring in the compressed state, the arm being restrained against pivoting movement by a member which moves to release the arm in response to a predetermined deceleration, there being a rotatable ball or roller between the arm and the said member.

7. A pre-tensioner for a vehicle safety-belt, incorporating a device to move an element which is directly or indirectly connected to the safety-belt, to impart a tension thereto; said device comprising: means to bias said element to effect movement thereof; a trigger to retain the element, but to release the element to effect said movement in response to a predetermined deceleration of the vehicle, thus applying tension to the safety-belt, the trigger consisting of a pivoted arm carrying means which engage said element, thus retaining the element in position, the arm being restrained against pivoted movement by a member which moves to release the arm in response to the predetermined deceleration, there being an intermediate element between the arm and the said member.

8. A pre-tensioner according to Claim 7 wherein the intermediate element is a ball or roller.

9. A pre-tensioner according to Claim 6 or Claim 8 wherein the ball or roller is engaged in a recess in the arm, and a recess in said member, and is not connected to the arm or the member.

10. A pre-tensioner according to Claim 6, 8 or 9 wherein the member is a pivotally mounted mass.

11. A pre-tensioner according to any one of the preceding Claims wherein the element forms part of or is connected to a cable which is connected to a buckle adapted to receive a tongue which is mounted on the safety-belt.