GB2175194A - Seat belt assembly - Google Patents

Abstract

A seat belt assembly includes a spool onto which a seat belt is wound, locking means adapted to selectively lock the spool to prevent further unwinding of the belt, and release means responsive to buckling of the belt for selectively disengaging said locking means to allow the belt to be freely wound and unwound from the spool except when the belt is buckled. <IMAGE>

Description

SPECIFICATION Seat belt assembly This invention relates in general to seat belt assemblies and more particularly, to a seat belt retractor having selectively engageable locking means and release means for disengaging said locking means except when the seat belt is buckled.

A number of different types of automatic seat belt retractor mechanisms are presently known. One type, often referred to as a "web-sensitive" seat belt retractor, senses a sudden unwinding of the belt and immediately locks the retractor spool to prevent further unwinding. No locking will occur as long as the belt is slowly unwound from the spool. Such a mechanism is convenient when used by adults, but has the disadvantage when used in a child restraint seat, that the child may work free of the belt or otherwise create excess slack or other unsafe conditions.

Another commonly employed type of automatic seat belt retractor includes a locking mechanism that allows the belt to be unwound from a spool as long as the belt is pulled continuously. If the unwinding of the belt is even momentarily reversed, a stop mechanism is activated to prevent further unwinding. The belt may be pulled from the spool and buckled around a user in a continuous motion.

Upon release, the belt automaticaily retracts and assumes a latched condition to restrain the user in the seat without further adjustment.

It is a disadvantage of this type of automatic retractor that even an adult user may misjudge the length of belt that must be withdrawn from the spool to pass around his body and may prematurely release tension on the belt before a sufficient length has been withdrawn. Once the belt is permitted to rewind, even slightly, further unwinding is impossible and the belt must be allowed to retract a sufficient distance to reset the locking mechnaism before the belt can again be unwound from the spool.

The problem becomes particularly bothersome when such an automatic retractor is used in connection with a child restraint seat. It may be difficult or impossible to withdraw the belt from the spool in a continuous motion while the child is resisting, pulling on the belt, or otherwise interfering with the necessary continuous unwinding of the belt. Where such an automatic retractor is used for older children who buckle themselves up, the required smooth continuous motion may be difficult for the child to effect., Accordingly, it is an object of this invention to provide a seat belt assembly that offers the advantages of automatic locking, but which does not require the continuous, smooth unwinding of the belt from the spool.

It is another object of this invention to provide a seat belt assembly that cannot be loosened after latching.

It is another object of this invention to provide a seat belt assembly that operates in a freewheeling mode when the belt is not buckled and in an automatic latching mode when the belt is buckled.

It is still another object of this invention to provide a seat belt assembly that is especially adapted for use in a child restraint seat.

Briefly stated and in accordance with a presently preferred embodiment of this invention, a seat belt assembly includes a spool onto which a seat belt is wound, locking means adapted to selectively lock the spool to prevent further unwinding of the belt, and release means responsive to buckling of the belt for selectively disengaging said locking means for allowing the belt to be freely wound and unwound from the spool except when the belt is buckled.

While the aspects of the invention that are regarded as novel are set forth with particularity in the appended claims, the invention itself, together with further objects and advantages thereof, may be more fully appreciated by reference to the following detailed description of the invention taken in conjunction with the accompanying drawings in which: Figure 1 is a side elevational view, partly in section, of a child restraint seat showing the seat belt assembly of this invention.

Figure 2 is a partial section of a portion of the seat of Figure 1 showing the seat belt assembly in a first position.

Figure 3 is a section similar two Figure 2 showing the seat belt assembly in a second position.

Figure 4s a bottom plan view of the ratcheting retractor of this invention.

Figures 5 and 6 are side views, partially in section, of a seat belt retractor assembly in accordance with an alternative embodiment of this invention.

Referring now to Figure 1, the seat belt assembly of this invention is illustrated in connection with a child's car seat designated generally at 10. Seat 10 includes a plurality of interconnected tubular frame members 13 supporting a generally vertical back rest portion 12 and a substantially horizontal seat portion 14 disposed in generally L-shaped configuration. Preferably, padded covering members 15 and 17 are disposed on the back and seat, respectively, by conventional means so as to allow removal for cleaning or replacement as necessary.

A seat belt retractor assembly 16 in accordance with the invention is mounted to the underside of seat 14 by a bolt 19 of any other conventional fasteners. A preferably webbed elongated belt 18 is lead rearwardly from retractor 16 behind back rest 12 and through at least one opening to the front of the seat. A padded chest protector 20 is attached to the free end of belt 18 and a buckle 22 is attached to the opposite end of protector 20.

Preferably, the free end of belt 18 that is attached to protector 20 is divided into first and second spaced-apart end sections adapted to pass on each side of the head of the child and to rest on the shoulders of the child in use. Such constructions are conventional. Buckle 22 is adapted to engage a tongue 24 fixed to seat portion 14 as shown in Figure 2.

The manner of operation of a conventional "automatic" seat belt retractor has already been described. The structure of such a retractor, modified in accordance with this invention, may be seen by reference to Figu res 2--4. In these figures, like and corresponding elements ofthe invention are designated by like reference numerals.

Figure 2 is a partial sectional viewofseat10 showing retractor 16. Retractor 16 is also shown in Figure 4. Retractor 16 includes a U-shaped base 30 having a mounting tab 32 including a mounting hole 34therethrough for receiving a bolt or similar fastenerforattachingthe retractor 16 to the underside of seat 14.

Downwardly depending side members 36 and 38 of base 30 support a spool 40 therebetween. One end of belt 18 is fixedly attached to spool 40 and is wound thereabout. Spool 40 is provided with spring means 41 attached to one end of the spool and to base 30 for continuously exerting a winding force on spool 40 to retract belt 18 towards a fully wound condition.

First and second ratchetwheels42 and 44are fixedly attached to the ends of spool 40 between the spool and the sides of base 30. A pawl 46 is pivotally mounted between side members 36 and 38 and includes engaging tabs 50 and 52forengaging ratchetwheels 42 and 44, respectively, and a beltengaging glide member 54 disposed approximately centrally of said pawl. Pawl 46 is biased into engagement with ratchet wheels 42 and 44 by pawl spring 58 having one end fixedly attached to base 30 and the other end attached to pawl 46. Spring 58 is shown schematically in Figures 2 and 3 and its actual form may be seen more clearly in Figure 4.

A rotating pawl cam 60 is disposed between ratchet wheel 44 and side member 36. As belt 18 is unwound from spool 40, pawl cam 60 rotates in the same direction as ratchet 44. The limits of rotation of cam 60 are defined by tab 62 on the peripherythereof and notch 64 in side member 36. Preferably, ratchet wheel 44 and pawl cam 60 are lightly frictionally coupled so that as spool 40 rotates in a counterclockwise direction, pawl cam 60 also rotates counterclockwise until tab 62 reaches the lower end of slot 64 as shown in the drawing.

When belt 18 is fully retracted, the belt engages glide member 54 and pushes pawl 46 out of engagement with ratchet wheels 42 and 44. As belt 18 is unwound, pawl cam 60 rotates to its counterclockwise limit of rotation (as seen in Fig.2) and cam surface66 engages pawl 46.The radius of pawl cam 60 at cam surface 66 is at least slightly larger than the maximum radius of ratchet 44. As long as belt 18is continuouslyunwoundfrom spool 40, pawl 46 is held out ofengagementwith ratchet 44 by cam 60. When belt 18 is allowed to rewind even slightly, cam 60 rotates clockwise and pawl 46 drops off cam surface 66 into position for engaging ratchets 42 and 44.

Ratchets 42 and 44 preventfurther unwinding of belt 18. Cam 60 can be reset only by allowing belt 18to rewind sufficiently to engage glide member 54 of pawl 46 as heretofore described.

This invention provides, forthefirst time, disengaging means for disabling the latching function exceptwhen buckle 22 is latched on tongue 24. An at least substantially rigid release actuator arm 21 is pivotally attached to the side of retractor 16.

A spring 23 or equivalent means biases release actuatorarm 21 upwards as shown in Figure 2.A lever arm 70 engages a laterally extending portion 68 of release actuator arm 21. Lever arm 70 is attached to a surface of pawl 46. Afree end 71 of arm 21 passes through an opening 72 in wall 74 of seat 14to a position adjacenttongue 24. Free end 71 is depressed by buckle 22 when the buckle is positioned on tongue 24. When release actuator arm 21 is depressed by engagementwith buckle 22, lever arm engaging portion 68 is disengaged from lever arm 70 and pawl 46 is free to move between latched and unlatched positions and the ratchet mechanism of seat belt retractor 16 operates in the normal manner.

As shown in Figure 3, when buckle 22 is removed from tongue 24, release actuatorarm 21 is moved to the position shown in Figure 3 by spring 23 and lever arm 70 is depressed by portion 68 of release actuator arm 21 to move pawl 46 out of engagement with ratchet wheels 42 and 44 and cam 60.

It will be appreciated that in the position shown in Figure3, belt 18 maybefreelywound and unwound from spool 40, notwithstanding the position of cam 60. Thus,the necessity for continuously unwinding the beltto avoid engaging the ratchet action is eliminated by this invention.

An alternative embodiment of the invention withoutthe automaticfeature ofthe embodiment shown in Figures 1-4 is illustrated at Figures 5 and 6.

In these two figures, like elements are designated by like reference numerals. Thefigures show the retractor in two positions, namely with the buckle installed on the buckle tongue (Figure 6) and with the buckle whollyor partly removed from the buckle tongue (Figure 5).

The retractor includes a buckle tongue 24formed in one leg of a U-shape member 76 with an extension 78 attached, for example, by rivet 94 to the frame 92 ofthe retractorassembly. A generally V-shaped lever arm 80 having a buckle engaging portion 81 is pivotally mounted on post 82. An opposite end 83 of the pivotal arm 80 engages spring clip 84. A pivotally mounted ratchet engaging pawl 88 is disposed betweenfirstspring clip 84and second spring clip86, both ofwhich are conveniently attached to frame 92 by rivet94. Normally, spring clips 84 and86 bias pawl 88to the position shown in Figure 5, that is, disengaged from ratchet 90. In this position, seat belt 18 isfree to wind and unwind from the spool.

As can be seen by referring now to Figure 6, when buckle 22 is latched on tongue 24, buckle engaging portion 81 of lever 80 is displaced towards the base of U-shaped member 76 causing spring 84to be displaced in a direction towards ratchet 90 and pawl 88 to be moved into a position for engaging ratchet wheel 90 to allow seat belt 1 8to be rewound, but not to be unwound bythecombined action of ratchet90 and pawl 88.

Accordingly, it can be seen thatthe embodiment of the invention illustrated in Figures 5 and 6 provides the essential features of this invention, but without the automatic features of the embodiments illustrated in the earlierfigures and with a substantial simplification in structure.

While the invention has been shown and described in connection with a presently preferred embodiment thereof, those skilled in the art wiil appreciate that many modifications and changes may be made without departing from the true spirit and scope of the invention which is intended to be defined solely by the appended claims.

Claims (16)

1. A seat belt assembly comprising: a spool; a belt wound on said spool; first attaching means on said belt; second attaching means for removably receiving said first attaching means; retractor means connected to said spool for causing said spool to rotate for winding said belt thereon; selectively engageable latch means connected to said spool for preventing rotation of the spool; and control means connected to said latch means for engaging said latch means only when said first and second attaching means are connected.

2. The assembly of Claim 1 wherein said latch means comprises; ratchet means attached to said spool; and pawl means adapted to selectively engage said ratchet means.

3. The assembly of Claim 2 wherein said control means comprises means connected to said pawl means for moving said paw out of engagement with said ratchet means.

4. The assembly of Claim 3 wherein said pawl comprises a pivotally mounted member biased into engagement with said ratchet.

5. The assembly of Claim 4 wherein said control means comprises a lever having a first end disposed adjacent said second attachment means and adapted to be engaged by said first attachment means when said first and second attachment means are connected.

6. The assembly of Claim 5 wherein said lever includes a pawl engaging portion for holding said pawl out of engagement with said ratchet except when said first and second attachment means are connected.

7. The assembly of Claim 5 further comprising means attached to said pawl and engageable by said lever for holding said pawl out of engagement with said ratchet except when said first and second attachment means are connected.

8. In a seat belt retractor of the type comprising a spool, a seat belt wound about said spool and spool locking means adapted to allow said seat belt to be continuously unwound from said spool, but for latching said seat belt when said unwinding stops or is reversed, the improvement comprising means for disengaging said latch mechanism for allowing said belt to be freely wound and unwound except when said belt is buckled.

9. The retractor of Claim 8 wherein said disengaging means comprises a lever.

10. The appparatus of Claim 9 further comprising a fixed tongue; a buckle adapted to engage said tongue; and wherein said lever is positioned adjacent said tongue for activation by said buckle when positioned on said tongue.

11. A seat belt retractor assembly comprising: a spool; a belt wound on said spool; ratchet means on said spool; pawl means adjacent said spool and cooperating with said spool for allowing said belt to be rewound onto said spool but preventing said belt from being unwound from said spool; a buckle on one end of said belt; means adjacent said spool for releasably receiving said buckle; and means movable between a first position when said buckle is positioned on said tongue and a second position when said buckle is at least partially disengaged from said tongue for disengaging said pawl from said ratchet except when said buckle is latched on said tongue.

12. The assembly of Claim 11 wherein said disengaging means comprises a lever having a first end adjacent to said tongue and a second end adjacent to and adapted to engage said pawl.

13. The assembly of Claim 11 further comprising first spring means engaging said pawl for biasing said pawl into a first position disengaging from said ratchet and second spring means engaging said pawl for biasing said pawl in a direction engaged with said ratchet, said first spring means being stronger than said second spring means so that said pawl is normally disengaged from said ratchet.

14. The assembly of Claim 13 wherein said lever engages said second spring means for adding to the force applied to said pawl by said second spring means and for displacing said pawl into engagement with said ratchet when said buckle is latched on said tongue.

15. The assembly of Claim 14 wherein said second spring means biases said lever into a first position for engaging said buckle as said buckle is moved into position on said tongue.

16. A seat belt assembly substantially as hereinbefore described with reference to Figures 1-4 or Figures 5 and 6 of the accompanying drawings.