GB2221605A

GB2221605A - Safety belt reel arrangement

Info

Publication number: GB2221605A
Application number: GB8818798A
Authority: GB
Inventors: Jorgen Ohlsson; Thomas Magnusson; Tommy Andersson
Original assignee: Autoliv Development AB
Current assignee: Autoliv Development AB
Priority date: 1988-08-08
Filing date: 1988-08-08
Publication date: 1990-02-14
Anticipated expiration: 2008-08-08
Also published as: GB8818798D0; GB2221605B; DE3926370A1

Description

PATENTS ACT 1977 P4348GB-NF/jlc

DESCRIPTION OF INVENTION

Improvements in or relating to a safety belt reel arrangement THE PRESENT INVENTION relates to a safety belt reel arrangement and more particularly relates to a safety belt reel arrangement for use in a motor vehicle. In particular the invention relates to a reel for a vehicle safety belt of the type in which a rotable shaft is adapted automatically to wind in the seat belt when the belt is not in use.

Modern safety belts in vehicles, particularly motor cars, are provided with a spring loaded reel comprising a winding spindle, which is arranged in a housing, on to which the safety belt is automatically wound when the safety belt is not in use. Such safety belts are normally provided with a locking mechanism for lock- ing the winding spindle when the belt is in use if the vehicle is suddenly accelerated or decelerated so that the safety belt cannot be extracted. This may occur if the vehicle turns sharply or is subjected to accident conditions. Also such safety belts'are normally pro- vided with a device for looking the winding spindle when the belt is extracted rapidly from the reel.

The means utilised to lock the spindle when the belt is extracted rapidly from the reel usually comprise an inertia mass mounted for rotation with the spindle. If the spindle rotates with undue rapidity, the inertia mass does not rotate as fast as the spindle, and this differential in rotation is sensed, causing locking to be effected.

When a person utilising a safety belt of this type takes the safety belt off, the safety belt is let go and is wound on to the reel automatically. It is possible for belt to be wound on to the reel with some speed, and then, when all the belt has been wound on to the reel, the reel suddenly stops rotating. The belt may, at this instant, be stretched beyond its normal length, since a safety belt is usually slightly elastic. Also, when the reel stops rotating the inertia mass, mentioned above, will rotatjc- relative to the spindle and may move the looking mechanism to a condition in which it can effect looking of the spindle. The tension in the belt will tend to rotate the reel in the "paying out" direction, and this may serve to bring the locking mechanism into engagement with the reel. The reel is thus locked and the tension in the belt acts to maintain the reel in a locked condition. Thus the stretched belt may hold the reel locked and it cannot be released easily when a person tries to use the belt.

The present invention seeks to provide a retractor reel assembly in which the risk of this situation arising is obviated or reduced.

According to this invention there is provided a retractor reel assembly for a vehicle safety belt comprising rotatably mounted means adapted automatically to wind a safety belt in when the safety belt is not in use, and means for locking said winding means to prevent the safety belt from being paid out, means responsive to the rate of belt withdrawal to actuate said locking means, means to sense the quantity of belt present on the reel and presence means responsive to a predetermined quantity of belt present on the reel to dis- able said means responsive to the rate of belt withdrawal.

p Thus when a 'predetermined quantity of belt is present on the reel, for example when virtually all of the belt that can be wound onto the reel has been wound onto the reel, the means responsive to the rate of belt withdrawal are disabled and thus cannot effect a looking of the spindle. When a short length of belt has been paid out from the reel, e.g. when a person pulls out a length of belt to put the belt on, the means responsive to the rate of belt withdrawal are re-enabled thus per- mitting looking to be effected if the belt is pulled out with a jerk.

Preferably means sensitive to acceleration or deceleration of the vehicle are additionally provided for actuating said locking means.

Conveniently the means to sense the quantity of belt present on the reel comprise a pivotally mounted lever, one end of the lever being in contact with the exterior of the belt present on the reel, another part of the lever serving to disable said means responsive to the rate of belt withdrawal. The said end of the lever may be in direct contact with the exterior of the belt, or may be in contact through an intermediate follower member.

Advantageously said means responsive to the rate of belt withdrawal comprise an inertia mass movable relative to a shaft of the reel, and the said disabling means comprise means adapted to prevent relative rotation between the inertia mass and the shaft of the reel.

Conveniently said disabling means comprise an element movable axially of the shaft, said element having means thereon adapted to engage the inertia mass and another member mounted on the shaft to prevent rotation of the inertia mass relative to the shaft.

Preferably the member movable axially of the shaft carries two axially protruding diametrically opposed pins, said pins being adapted to pass through apertures formed in an element mounted on the shaft of the reel and to engage apertures present in the inertia mass to prevent relative rotation of the inertia mass.

Advantageously the member adapted to engage the inertia mass is rotatably mounted within a drive member, means being provided to drive the drive member axially of the shaft of the reel.

Preferably the drive member is mounted on a base member, therebeing a screw thread or other cam connection between the drive member and the base member, said,means responsive to the quantity of belt present on the reel causing the drive member to be rotated, thus causing the drive member to move axially of the shaft of the reel.

In order that the invention may be more readily understood, the invention will now be described, by way of example, with reference to the accompanying drawings in which, FIGURE 1 is an exploded perspective view of a prior art safety belt arrangement, and

FIGURE 2 is an exploded view of part of an embodiment of the invention which is a modification of the seat belt shown in Figure 1.

Referring initially to Figure 1 a safety belt arrangement incorporates a metal housing 1 which defines apertures to receive the various components to be des- 1 cribed. One side wall of the housing defines an aper ture 2 which accommodates a bearing 3. Part o - f the bearing is inserted into a housing 4 which contains a helical spring. A cover 5 is retained on the housing 4 by means of screws 6. A bobbin or reel 7 is provided which is mounted on a shaft 8. One end of the shaft 8 is received within an appropriate recess 9 formed in the bearing 3, so that the bearing rotatably supports that end of the shaft. The helical spring contained within the housing 4 is connected to the bearing or to the shaft in such a way that a rotary bias is imparted to the shaft 8.

The other end of the shaft 8 is inserted into a corresponding bearing 10 which is mounted in another aperture 11 formed in the metal housing 1.

The bobbin or reel 7 is provided to have a seat belt wound on to it, and the spring in the housing 4 tends to wind the belt on to the bobbin or reel.

A cover 12 is provided located between the part of the housing defining the aperture 11 and the bobbin 7. A toothed looking wheel 13 is mounted on the shaft 8 for rotation with the shaft between the housing 12 and the bearing 10. The wheel 13 cannot rotate relative to the shaft 8.

A plastic material control element 14 is lo- cated adjacent the exterior of the housing 1, one face of the control element defining a recess 15. The inner periphery of the recess is toothed. The recess 15 accommodates a second toothed locking wheel 16, and two elements 17, 18 to sense only a sudden movement or jerk of the belt stored on the bobbin 7. The element 17 is a lighweight follower which is securely connected to the element 18 which is in the form of an annular metallic mass. The elements 17, 18 thus move together as a single component. The recess 15 also accommodates a further toothed wheel 19. A housing 20 is provided which effectively covers and protects these components. The components are mounted coaxially with the shaft for rotation about the shaft axis. The wheels 16, 19 are keyed to the shaft and cannot rotate relative to the shaft. The control element 14 and the movement sensing elements 17, 18 can, however, rotate relative to the shaft.

Pivotally mounted on the control element 14 is a pivotally mounted member 21 which is adapted to be moved by a force sensitive device'such as a pendulum or "standing man". The pivotally mounted member 21 is located so that it can be moved pivotally to a position in which one end of the member 21 engages the toothed wheel 19 and when the toothed wheel 19 is engaged by the member 21 the control element 14 will be constrained to rotate with the shaft 8. When the force sensitive device senses a certain force, and the belt is pulled out, the control element rotates with the shaft, which leads to a locking of the shaft as will now be described.

A spring 22 is provided to bias the control element 14 rotationally to an initial starting position.

Two looking tabs 23 are provided which are located in appropriately positioned and configured apertures 24 in the part of the housing 1 that defines_ the aperture 11. The looking tabs are pivotally mounted in position. The control element 14 has two wings 25 extending from the rear wall and extending radially outwardly of the side wall. On rotation of the control element 14 from its initial starting position the wings 25 engage the locking tabs 23, moving the locking tabs 1 23 pivotally in such a way that part of each locking tab extends to contact with the first locking wheel 13 and, through the aperture formed in the control member 14 ad jacent the wing 25, with the second looking wheel 16.

With the tabs 23 engaging the toothed wheels 13 and 16 the shaft is locked against further rotation.

The arrangement may be such that the control element 14 rotates by a predetermined amount befor the looking tabs are engaged by the wings 25 and are moved to engage the said toothed wheels 13, 16. Altern atively, the wheel 19 may be mounted on the shaft in such a way that the shaft can rotate by a small amount even when the wheel 19 is engaged by the member 21. In such a case a short length of belt may be withdrawn before locking occurs.

It is to be noted that Figure 1 illustrates a pivoted lever 26 which is pivotally mounted on an app ropriate spindle provided on the wheel 19. A spring 27 is provided to bias the lever to a predetermined pos ition. One end of the spring engages one end of the pivoted lever 26, and the other end of the spring en gages a stop provided on the wheel 19. The other end of the lever engages a radially outwardly directed pro jection 28 provided on the element 17. The spring 27 and the associated lever 26 are so designed and located that the inertia mass is usually biassed to a position.

relative to the wheel 19 such that the pivoted lever 26 does not engage the toothed interior of the plastic control element 14. However, if the inertia mass 18 moves relative to the wheel 19, against the bias im parted by the spring 27. then the projection 28 presses against the lever 26 which is moved so that part of the lever contacts the toothed interior of the recess 15 in the control element 14. Thus the control element 14 is caused to rotate with the shaft. As the control element 14 moves with the shaft the wings 25 engage with the locking tabs 23, pulling them into engagement with the toothed wheels 13 and 16, thus looking the shaft.

It is to be understood that if the inertia mass 18 moves relative to the shaft when the safety belt has been fully wound on to the shaft, and when the safety belt is slightly stretched, as the tension in the stretched belt causes the shaft 8 to rotate in the anti- clockwise direction as shown in Figure 1, the control element 14 will be caused to rotate with the shaft. and the locking tabs will be moved to the looking position. The shaft is then inadvertently locked, and the shaft cannot be moved in either direction when a person tries to use the belt.

Figure 2 is a view of an embodiment of the invention. The similarity between the invention and the prior art described above will be immediately apparent, and like references are used for like parts, which will not be re- described.

Referring now to Figure 2, the illustrated reel is provided with an acceleration sensitive device 30, of conventional design, which is adapted to engage the toothed wheel 19 via an arm 21 when a motor vehicle in which the safety belt is fitted is subjected to a severe deceleration, to lock the shaft against further rotation.

Additionally the reel is provided with means, about to be described. which serve to lock the inertia mass 18. and the associated follower element 17. in position relative to the adjacent toothed wheel 19 when almost all the safety belt has wound back on to the reel. The inertia mass will only be locked in position when virtually all the safety belt is present on the 1 1 reel, and thus will not be locked in position when the safety belt is being worn by a passenger, since in that situation at least a significant part of the safety belt will be withdrawn from the reel.

The presently described reel incorporates a belt sensing lever 31 which is pivotally mounted on the cover 20 by means of a pivot shaft. One end 34 of the lever 31 is co-operating with a follower member 32 which is insertable into an aperture 33 formed in the cover 12. The member 32 engages the outer circumference of the seat belt wound on to the bobbin 7. It will be appreciated that as the amount of seat belt wound on to the bobbin 7 increases, so the member 32 and the free end 34 of the lever 31 will be displaced, thus causing an operative end 35 of the lever to execute a corres ponding motion.

Mounted within the housing 20 is a fixed base member 36. The base member 36 defines a protruding pin 37 on which the toothed wheel 19, the inertia weight 18 and the associated member 17 are mounted for pivotal rotation. The protruding pin 37 may be formed of a low friction material, such as nylon.

The fixed base member 36 also defines two outer opposed arcuate walls 38, 39 and on the interior of each of these is formed a part helical groove 40 thus constituting effectively a screw thread.

Received within the part of the base member 36 between the outer arcuate wall 38, 39 and the central protruding boss 37 is a drive member 41. The drive member is of annular form, but has, on its outer periphery, two part helical projections 42 adapted to be slidably received within the helical grooves 40. A radially extending arm 42A engages the operative end 35 of the lever 31. The arrangement is such that, as the lever 31 tilts, the arm 42A is driven tangentially, thus causing the drive member 41 to be rotated and thus to be driven axially in and out of the fixed member 36 by the interengaging helical projections 42 and groove 40.

Rotatably mounted within the drive member 41 is a rotor 43. The rotor 43 carries two diametrically opposed axially extending pins 44. It can be seen that as the drive member 41 is driven in and out, so the pins 44 are driven axially. The pins may pass through apertures provided in the toothed wheel 19, and engage part of the member 17, thus preventing movement of the member 17 relative to the toothed wheel 19. Thus, effectively, this serves to dis-able the locking means sensitive to the rate of belt withdrawal.

When the drive member 41 is in a retracted position, the tips of the pins 44 will remain in the aper- tures in the toothed wheel 19, and the member 41 will rotate in synchronism with the wheel 19. Thus the pins will be correctly aligned ready to be brought to the position where relative movement of the inertia mass is prevented as soon as a sufficient quantity of belt is on the reel.

It will thus be understood that when a significant part of the seat belt has been withdrawn from the reel, the described arrangement operates in exactly the same manner as the arrangement described with reference to Figure 1. However. when the significant length of belt has been wound on to the bobbin 7 the lever 31 moves. thus causing the member 41 to move axially, causing the pins 44 to lock the inertia weight in position relative to the toothed wheel 19, and then the inertia weight cannot move to lock the reel.

Whilst the invention has been described with reference to one specific embodiment, many modifications may be effected without departing from the invention.

Claims

CLAIMS:

1. A retractor reel assembly for a vehicle safety belt comprising rotatably mounted means adapted auto matically to wind a safety belt in when the safety belt is not in use, and means for locking said winding means to prevent the safety belt from being paid out, means responsive to the rate of belt withdrawal to actuate said locking means. means to sense the quantity of belt present on the reel and means responsive to a pre determined quantity of belt present on the reel to dis able said means responsive to the rate of belt with drawal.

2. A retractor reel according to Claim 1 wherein means sensitive to acceleration or deceleration of the vehicle are provided for actuating said locking means.

3. A retractor reel according to Claim 1 or 2 wherein the means to sense the quantity of belt present on the reel comprise a pivotally mounted lever, one end of the lever being in contact with the exterior of the belt present on the reel, another part of the lever serving to disable said means responsive to the rate of belt withdrawal.

4. A retractor reel according to any one of the preceding Claims wherein said means responsive to the rate of belt withdrawal comprise an inertia mass movable relative to a shaft of the reel or an element mounted on the shaft of the reel, the said disabling means compris ing means adapted to prevent relative rotation between the inertia mass and the shaft of the reel.

5. A retractor reel assembly according to Claim 4 wherein said disabling means comprise an element -movable axially of the shaft, said element having means thereon adapted to engage the inertia mass and another member mounted on the shaft to prevent rotation of the inertia mass relative to the shaft.

6. A retractor assembly according to Claim 5 wherein the member movable axially of the shaft carries two axially protruding diametrically opposed pins, said pins being adapted to pass through apertures formed in an element mounted on the shaft of the reel and to en- gage apertures present in the inertia mass to prevent relative rotation of the inertia mass.

7. A retractor reel according to Claim 5 or 6 wherein the member adapted to engage the inertia mass is rotatably mounted within a drive member, means being provided to drive the drIve member axially of the shaft of the reel.

8. A retractor reel substantially as herein described with reference to and as shown in Figure 2 of the accompanying drawings.

Published 1990atThe Patent Office. State House. 6671 High Eolborn.Londor. WC1R4TP. Further copies maybe obtained from The Patent Office Sales Branch. St Mary Cray. Orpingtor- Kei t BR5 3RD- Primed by WAInp2ex techniques lta. St Mary Cray. Kent. Con P87

8. A retractor reel assembly according to Claim 7 wherein the drive member is mounted on a base member, therebeing a screw thread connection between the drive member and the base member, said means responsive to the quantity of belt present in the reel causing the drive member to be rotated, thus causing the drive member to move axially of the shaft of the reel.

9. A retractor reel substantially as herein des cribed with reference to and as shown in Figure 2 of the accompanying drawings.

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

4 -14.

Amendments to the claims have been filed as follows 1. A retractor reel assembly for a vehIcle safety belt comprising rotatably mounted means adapted automatically to wind the safety belt in when the safety belt is not in use, and means for locking said winding means to prevent the safety belt from being paid out, means responsive to the rate of belt withdrawal to actuate the locking means, and comprising an inertia mass moveable relative to the shaft of the reel, or relative to an element mounted on the shaft of the reel, the locking means beIng actuated when the inertia mass has moved by a pre-determined amount relative to the said shaft or element, the assembly further comprising means to sense the quantity of belt present on the reel adapted to prevent relative rotation between the inertia mass and the shaft of the reel whenever the quantity of belt present on the reel is below a pre- determined minimum quantity.

A retractor reel according to Claim 1 wherein the means to sense the quantity of belt present on the reel comprise a pivotally mounted lever, one end of the lever being in contact with the exterior of the belt present on the reel, another part of the lever serving to actuate the said means adapted to prevent relative rotation between the inertia mass and the shaft.

3. A retractor reel assembly according to Claim 1 and 2 wherein said means to prevent relative rotation comprise an element moveable axially of the shaft, said element having means thereon adapted to engage the inertia mass and another member mounted on the shaft to prevent rotation of the inertia mass relative to the shaft.

115- 4. A retractor member according to Clailm 3 wherein the member moveable axially of the shaft carries two axially protruding diametrically opposed pins, said pins being adapted to pass through apertures formed in an element mounted on the shaft of the reel and to engage apertures present in the inertia mass to prevent said relative rotation of the inertia mass.

5. A retractor reel according to Claim 3 or 4 wherein the member adapted to engage the inertia mass is rotatably mounted within a drive member, said means to sense the quantity of belt present on the reel being operative to drive the drIve member axially over the shaft of the reel.

6. A retractor reel according to Claim 5 wherein the drive member is mounted on a base member, there being a screw thread connection between the drive member and the base member, said means to sense the quantity of belt present on the reel causing the drive member to be rotated, thus causing the drive member to move axially over the shaft of the reel.

7. A retractor reel according to any one of the preceding Claims wherein additional means, sensitive to acceleration or deceleration of the vehicle are provided for actuating said locking means.