GB2201449A - A locking device - Google Patents

Abstract

A locking arrangement selectively locks in position a first element which is movably mounted to a second element. One element carries a rack 12, and the other element carries two gear wheels 16, 17 each engagable with the rack. The gear wheels may be moved from a position in which they are prevented from rotating (Fig 4) to a position in which they are free to rotate (Fig 3). Other embodiments are described. <IMAGE>

Description

DESCRIPTION OF INVENTION Improvements in or relating to a locking device.

THE PRESENT INVENTION relates to a locking device, and more particularly the invention relates to a locking device adapted to lock a movable component relative to a fixed component, the locking device being such that the movable component may be locked relative to the fixed component at any position within a predetermined path of travel.

It- has been proposed previously to provide locking devices to lock a movable component relative to a fixed component. For example, the seats present in motor cars have been mounted in channels for a sliding movement in a forward and backward direction. Means have been provided to lock the seat in various selected positions within the limited path of movement. A typical locking means provides a number of spaced holes or detents formed in the channel, and a spring-biased locking member attached to the chair which can engage a hole or detent when the chair is in an appropriate position.

It is to be understood that the locking member will only engage the hole or detent when the chair is in an. appropriate position, with the locking member aligned with the hole or detent and should the chair be in an intermediate position, the locking member will engage the channel. If the chair is moved slowly the locking member may engage or lock in an adjacent hole or detent.

However, if the chair is moved suddenly there is not ùffletent time for the bolt to engage the hole or detent, and this can lead to 'skipping' and/or distruction of the locking member.

Similar locking systems have been used in many situations, for example with a device to adjust the height of the pillar loop on a motor vehicle safety belt system.

FIGURE 1 of the accompanying drawings illustrates a locking device of this type in which a plate 1 is provided with evenly spaced apertures 2. A member 3 that slides adjacent the plate carries a locking member 4 having teeth 5 adapted to engage the apertures 2. A spring 6 is provided to biased the teeth 5 into engagement with the apertures.

According to this invention there is provided a locking arrangement for selectively locking in position a first element which is movably mounted relative to a second element, one of said elements carrying rack and the other of said elements carrying at least part of a gear means engagable with the rack, said gear means comprising at least two gear wheels each engaging part of the rack, the gear means being movable from a condition in which the said two gear-wheels are prevented from rotating, to a position in which the said two gear wheels are free to rotate.

The terms 'rack' and 'gear wheel' are used in a broad sense to include not only a toothed rack and toothed gear wheels, but any rack and wheels with meshing or interengaging surfaces that can provide a nonslip engagement.

In one embodiment said gear wheel arrangement comprises two gear wheels engaging a common rack, one of the gear wheels being movable into and out of engagement with the other said gear wheel.

The gear wheels may be spring biased together and selectively manually operable means are provided to move the gear wheels apart,or the gear wheels may be spring biassed apart and means may be provided to move the gear wheels into engagement.

One embodiment comprises three gear wheels engaging a common rack, the two end gear wheels being movable into and out of engagement with the central gear wheel.

Preferably one said gear wheel is mounted on the respective element carrying said gear means, and the other gear wheel is mounted on a member that is movably mounted on the said respective element, movable between positions in which the other gear wheel is in engagement with the first gear wheel and out of engagement with the first gear wheel, means being provided for moving said movable member to bring the second gear wheel into and out of engagement with the first gear wheel.

Preferably the means adapted to move the movable member comprises means adapted to apply a force directly to the movable member.

Conveniently the means to move the movable member comprise an elongate cable extending around two pulleys, one end of the cable engaging the said respective element on which the wheels are mounted, and the other end of the cable engaging said movable member, at least one of the pulleys being such that the effective diameter thereof can be increased or decreased selectively in order to move the movable member.

Advantageously the movable member comprises a pivotally mounted arm spring biased to a position in which the two gear wheels are in engagement with each other.

In an alternåtive embodiment the rack means comprise two opposed rack portions, and the gear wheel means comprises three wheels, one engaging one rack portion, another engaging the outer rack portion, and an intermediate gear wheel engaging said one gear wheel and said another gear wheel.

Preferably the gear wheels are provided with non-symetrical gear teeth.

A locking arrangement according to the invention may be incorporated in a slide mechanism for adjusting- the position of a vehicle seat, or in a slider mechanism for adjusting the position of a headrest, or in a slider mechanism for adjusting the position of a pillar loop of a safetly belt.

In order that the invention maybe more readily understood, and so that further features thereof may be appreciated, the invention will now be described, by way of example, with reference with the accompany drawings in which: FIGURE 2 is a side diagrammatic view of one embodiment of the invention, FIGURE 3 is a view of the embodiment of figure 2 in the locking condition, FIGURE 4 is a diagramatic view showing two mating cog wheels, FIGURE 5 is another diagramatic view correspo nding to figure 5 but illustrating another embodiment, FIGURE 6 is a view corresponding to figures 2 and 3 illustrating a modified embodiment of the inventi on, FIGURE 7 is a view corresponding to figures 2 and 3 illustrating a further modified emobodiment of the invention, and FIGURE 8 is another diagramatic view illustra ting a further embodiment of the invention.

Embodiments of the invention incorporate a fi xed element carrying a first surface which may be in the form of a toothed rack adapted to engage with two or mo re toothed gear wheels or sprockets. Whilst the invent ion will be described in such terms it is to be underst ood that in alternative embodiments of the invention any surface or surfaces may be utilised which will engage w ith wheels or rollers in a non-slip manner may be utili sed.

Refering now to figures 2 and 3 of the accompanying drawings, an embodiment of the invention is illu strated in which there is a plate 10 provided with aper tures 11 by means of which the plate may be mounted in position on a motor vehicle. The plate defines a tooth ed rack 12 and also defines an elongate guide i3 which guides shafts 14, 15 on which are mounted toothed wheels 16, 17. The toothed wheels may be adapted to move with an element movable relative to the fixed plate 10.

The toothed wheels 16, 17 have their toothed p eripheries in engagement with the rack 12. One of the toothed wheels is movable relative to the other toothed wheel so that the wheels may either be in the condition illustrated in figure 2 in which the peripheries of the toothed wheels do not contact each other or or the toot hed wheels may be in the condition illustrated in figure 3, in which the peripheries of the toothed wheels do en gage with each other, with the teeth of the wheels 16 being intermeshed with the teeth of the wheel 17.

However, the said other toothed wheel is mounted to move with the movable element so that if said other toothed wheel is prevented from moving then the movable element is prevented from moving.

It will be understood that with the apparatus in the condition illustrated in figure 2, both the toothed wheels are free to rotate, and thus the wheels may move along the rack 12. Thus a movable element on which the wheels are mounted may move relative to the rack.

However, when the wheels are move to the condition illustrated in figure 3, with the peripheries of the two wheels meshed, and with each wheel mested with the rack, the wheels cannot rotate, and thus the wheels cannot move along the rack, and consequently the movable member on which the wheels are mounted is locked in position and cannot move relative to the rack.

It is envisaged in preferred embodiments of the invention a resilient member or spring may be provided.

In certain embodiments the resilient member may tend to push the toothed wheels apart. Means may be provided to respond to an emergency situation to overcome the spring bias pushing the wheels apart, to force the wheels together, thus consituting an emergency locking device.

Alternatively the spring may tend to bias the wheels together, and in that situation manually operable means may be provided to separate the wheels against the spring bias, thus permitting the described device to be adjusted and then again to be locked in a new adjusted position.

Locking of the wheels can be accomplished at many positions along the length of the rack, at any position at which the teeth of the various wheels will interengage.

Conventional gear wheel teeth may have flattened points and thus may not engage each other easily.

It is desired that the teeth should engage each other in an easy manner to ensure that when the wheels are desired to lock they become locked as quickly as possible.

It is thus preferred to use pointed teeth. As can be seen from figure 4, even if the teeth are pointed, if the teeth of the wheels 20 are of a symetrical design, there are a few points at which the teeth will not interengage whereas, as can be seen from figure 5, if the teeth 21 have a non-symetrical design, then it is possible for the locking action to commence at virtually any point along the rail. thus the non-symmetrical teeth are to be preferred if a perfect result is to be obtained.

In certain cases, where a high degree of precision is required , it may be essential to ensure that locking can be accomplished at every point on the rail.

If it is found that the design of the teeth is such that locking cannot be accomplished at every point on the rail, it may be necessary to provide the movable member with more than one pair of interengagable locking toothed wheels engaging the rack, the locking wheels being so positioned that if one pair of locking wheels cannot lock, another pair of locking wheels, which are out of phase with respect to the first pair, can lock.

It is to be understood that the two wheel.em- bodiment described above, whilst providing a locking effect- when the wheels are engaged with each other does have a slight drawback if one wheel is only resiliently biassed into engagement with the other wheel. In such a case, while the device will remain locked even if subjected to a very large force in one direction, the device will be released if subjected to a force in the other direction which is suffiecient to overcome the resilient force biassing the wheels together. Thus the device might be considered to be a mechanical diode, with the device remaining locked when subjected to a force in one direction, and acting as a ratchet when subjected to a force in the other direction. As can be seen from figure 6 it is possible to utilise three toothed wheels 30, 31, 32 engaging a common rack 33.If an embodiment of this type is used it is possible to ensure that the device can withstand a force in either direction. A device of this type may thus be used, for example-, on the slider mechanism mounting a chair in a motor vehicle. In one such an arrangement one wheel 30 will be movable into and out of engagement with the central wheel 31 and also the remaining wheel 32 will.be movable into and out of engagement with the central wheel 31. It is to be appreciated that in an embodiment of this type it is possible, for example, for the wheel 30 to be resiliently biased into engagement with the wheel 31, the wheel 30 being moved out of engagement with the wheel 31 by manual pressure applied to overcome the resilient bias, before the described assembly of wheels can be moved relative to the rack 33.Also, the wheel 32 will be spring biased out of engagement with the wheel 31, but is provided with means operable in response to an emergency situation to overcome the spring bias to force the wheel 32 into engagement with the wheel 31, thus providing an emergency locking effect.

Figure 7 illustrates another embodiment of the invention in which the rack is formed of two opposed rack portions 40, 41. A series of three toothed wheels are provided, comprising a first toothed wheel 42 which engages the rack 41, a second toothed wheel 43 which engages the toothed wheel 42 and a third toothed wheel 44 which engages the toothed wheel 113 and the rack portion 40. When the wheels are in engagement, in the condition illustrated, it is not possible for the toothed wheels to rotate and thus if the toothed wheels are mounted on a member movable relative to the rack, when the wheels are in engagement as illustrated that movable member cannot move relative to the rack.

However, it is to be understood that if either the toothed wheel 44 is moved to the right, thus disengaging from toothed the wheel 43 or if the toothed wheel 42 is moved to the left, thus disengaging from the toothed wheel 43, then the toothed wheels will be able to rotate, and the member on which the toothed wheels are mounted may be moved relative to the rack.

Figure 8 illustrates an embodiment of the invention in which a rack 50 is provided, and two toothed wheels 51, 52 are provided, having their toothed peripheries engaging the rack 50, the toothed wheels 51 and 52 being movable between a position in which their peripheries interengage and and a position in which their peripheries are disengaged. The wheel 51 is mounted on a plate 53. In contrast the wheel 52 is mounted on an arm 54, the arm being pivotally mounted on the plate 53, there being a spring 55 which biases the arm so that the peripheries of the wheels 51, 52 are brought into engagement. A cable or wire 56 extends from the plate 53, around a pulley located on one side of the plate 53 in the direction of movement thereof, back around another pulley 58, located to the other side of the plate 53 in the direction of movement thereof, the wire or cable 56 then engaging the free end of the arm 511, that is to say the end 59 thereof remote from the pivotally 60 mounted end thereof. The cable 56 is such a length that the gear wheels are in engagement.

One of the pulley wheels 57, 58 is designed such that it enlarges its diameter, when turned to the left or the right. For example, the pulley may be formed of a plurality of segments having inner faces inclinded to the axis of the pulley, thus forming ramps or camming faces, and a central element may be provided which moves axially thus forcing the segments radially outwardly, thus enlarging the diameter of the pulley. Alternatively the pulley may be mounted in a movable manner so that the pully can move in a direction away from the other pulley.In any event, the effect is that as the pulley is rotated, so a tension is applied, through the cable, to the end 59 of the swinging arm 511, thus causing that arm to swing about the pivot 60 against the bias from the spring 55, thus dis-engaging the toothed wheel 52 from the toothed wheel 51, thus enabling the plate 53 to move relative to the rack. As the plate moves, the pulleys 57, 58 will rotate, thus maintaining the wheel 52 out of engagement with the wheel 51 until such time that the diameter of the adjustable diameter pulley is returned to its original size. This embodiment provides means which move the pivotally mounted arm to disengage the toothed wheels. Many such means may be provided including means which exert a 'pushing' force, as opposed to the presently described means which exert a 'pulling' force.

Whilst the invention has been described with reference to embodiments in which the racks are of a linear form it is to be understood that in alternative embodiments of the invention the racks may be of curved form, so as to conform to the shape of part of a motor vehicle body, for example, such as the 'B' post, or may even be of circular form. The invention may find may applications in connection with motor vehicles, and locking devices in accordance with the invention may be utilised on, for example, a slider mechanism for adjusting the position of a seat, a slider mechanism for a-djusting the position of a headrest, or a slider mechanism for adjusting the position of a pillar loop.

Claims (19)

CLAIMS:

1. A locking arrangement for selectively locking in position a first element which is movably mounted relative to a second element, one of said elements carrying rack and the other of said elements carrying at least part of a gear-means engagable with the rack, said gear means comprising at least two gear wheels each engaging part of the rack, the gear means being movable from a condition in which the said two gear wheels are prevented from rotating, to a position in which the said two gear wheels are free to rotate.

2. A locking device according to claim 1, wherein said gear wheel arrangement comprises two gear wheels engaging a common rack, one of the gear wheels being movable into and out of engagement with the other said gear wheel.

3. A locking arrangement according to claim 2, when the gear wheels are spring biased together and selectively manually operable means are provided to move the gear wheels apart.

11. A locking arrangement according to claim 2, wherein the gear wheels are spring biassed apart and means are provided to move the gear wheels into engagement.

5. A locking engagement according to any one of the preceeding claims comprising three gear wheels engaging a common rack, the two end gear wheels being movable into and out of engagement with the central gear wheel.

6. A locking arrangement according to any one of claims 1 to 4 wherein one said gear wheel is mounted on the respective element carrying said gear means, and the other gear wheel is mounted on a member that is movably mounted on the said respective element, movable between positions in which the other gear wheel is in engagement with the first gear wheel and out of engagement with the first gear wheel, means being provided for moving said movable member to bring the second gear wheel into and out of engagement with the first gear wheel.

7. A locking arrangement according to claim 6 wherein the means adapted to move the movable member comprises means adapted to apply a force directly to the movable member.

8. A locking arrangement according to claim 6 wherein the means to move the movable member comprise an elongate cable extending around two pulleys, one end of the cable engaging the said respective element on which the wheels are mounted, and the other end of the cable engaging said movable member, at least one of the pulleys being such that the effective diameter thereof can be increased or decreased selectively in order to move the movable member.

9. A locking arrangement according to claim 6, 7 or 8 , wherein the movable member comprises a pivotally mounted arm spring biased to a position in which the two gear wheels are in engagement with each other.

10. A locking device according to claim 1, wherein the rack means comprise two opposed rack portions, and the gear wheel means comprises three wheels, one engaging one rack portion, another engaging the outer rack portion, and an intermediate gear wheel engaging said one gear wheel and said another gear wheel.

11. A locking arrangement according to any one of the preceeding claims wherein the gear wheels are provided with non-symetrical gear teeth.

12. A locking arrangement according to any one of the preceeding claims incorporated in a slide mechanism for adjusting the position of a vehicle seat.

13. A locking mechanism according to any one of the preceeding claims incorporated in a slider mechanism for adjusting the position of a headrest.

14. A locking mechanism according to any one of the preceeding claims incorporated in a slider mechanism for adjusting the position of a pillar loop of a safetly belt.

15. A locking mechanism substantially as herein described with reference to and as shown in figures 2 and 3 of the accompanying drawings.

16. A locking mechanism substantially as herein described with reference to and as shown in figure 6 of the accompanying drawings.

17. A locking mechanism substantially as herein described with reference to and as shown in figure 7 of the accompanying drawings.

18. A locking mechanism substantially as herein described with reference to and as shown in figure 8 of the accomapanying drawings.

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