The invention has been devised in relation to the mounting of a seat in a motor vehicle, which enables the seat to be moved, when required, forwardly and rearwardly in the vehicle. Such a mounting characteristically is provided for the driver's seat of a vehicle and also for the front passenger's seat of a vehicle such as a passenger car. Such a seat mounting usually comprises, at each side of the seat, a track which is attached to the vehicle's floor pan and a slider assembly attached to the seat and cooperating with the track so as to be movable therealong, the slider assembly carrying a movable locking device which is able to cooperate with locking formations spaced along the track in order to lock the slider assembly in position relative to the track. In one known construction, the locking device includes a locking member which is pivotally mounted on the slider assembly, and which is provided with teeth at a portion remote from its pivotal mounting to engage the locking formations which are in the form of windows or apertures spaced along the track. Pivotal movement of the locking member causes movement of the portion thereof having the teeth in a direction transversely to the length of the track, to engage with or disengage from the windows in the track.

Such a locking mechanism has some disadvantages. One is that the seats can only be locked at positions in its path of movement in which the teeth on the locking member can properly engage with the windows in the track. Because the teeth and the windows must be made fairly large in order to be robust and have a long service life, the increments of adjustment of the seat position must also be large, with very fine adjustment of the seat position not being possible. A second disadvantage is that if the seat should be positioned such that the teeth on the locking member cannot properly engage in the track windows, the geometry of the locking mechanism is such that the unlocked seat will not always lock in the next available locking position when the seat is suddenly accelerated, as in a crash situation. Usually it is arranged so that if the seat is suddenly accelerated forwardly the locking mechanism will engage to prevent further forward seat movement, but if the seat is accelerated rearwardly the locking performance is not so good. The locking mechanism behaves analogously to a ratchet and pawl mechanism.

Accordingly it is the object of the present invention to provide a locking mechanism suitable for a vehicle seat, in which the above described disadvantages are overcome or reduced.

According to one aspect of the present invention, we provide a locking mechanism for locking a slider assembly movable lengthwise of a track in a required position relative to the track, said locking mechanism comprising a plurality of locking formations spaced along said track; two locking members pivotally mounted relative to the slider assembly, each locking member being provided at a position remote from its pivotal mounting with a locking portion movable transversely of the track upon pivotal movement of the locking member and cooperable with the locking formations for locking the slider assembly against movement lengthwise of the track; said two locking members extending in opposite directions lengthwise of the track from their pivotal mountings to their respective locking portions.

According to another aspect of the present invention, we provide a vehicle seat mounting comprising a track and a slider assembly movable lengthwise of the track, and a locking mechanism comprising a plurality of locking formations spaced along said track; two locking members pivotally mounted relative to the slider assembly, each locking member being provided at a position remote from its pivotal mounting with a locking portion movable transversely-of the track upon pivotal movement of the locking member and cooperable with the locking formations for locking the slider assembly against movement lengthwise of the track; said two locking members extending in opposite directions lengthwise of the track from their pivotal mountings to their respective locking portions.

In a vehicle seat locking mechanism according to the invention, the arrangement of the locking members extending in opposite directions relative to one another between their pivotal mountings and their respective locking portion means that one or other of the locking members will engage with the locking formations whichever direction an unlocked seat is moved.

Preferably the distance between the locking portions of the two locking members does not correspond to an exact multiple of the spacing between adjacent locking formations on the track.

This enables a finer adjustment of seat position to be provided, since one of the locking members is able to have locking engagement with the track at a position intermediate adjacent positions at which the other locking member is able to have such engagement.

Preferably both the locking members are able to be pivotally moved in directions to cause their locking portions to disengage from the track by releasing movement of a common releasing member.

The invention will now be described by way of example with reference to the accompanying drawings, of which: Figure 1 is a somewhat simplified side view of part of a seat mounting arrangement for a motor vehicle, in accordance with the invention; Figure 2 shows a modification of part of Figure 1.

Referring to the drawing, part of a track member of a seat mounting is indicated at 10. It is secured to the floor pan of a vehicle such as a passenger car, at spaced positions such as indicated at 11,12: at 12 there is a transverse member which connects the track member 10 to a corresponding parallel track member notshown at the opposite side of the seat.

The seat carries two laterally spaced slider assemblies cooperating with the respective track members and a slider assembly engaging with the track member 10 is indicated generally at 13. In the region of the track member 10, the shape of the slider assembly 13 is such as to cooperate with the track member to enable it to slide lengthwise of the track member while remaining captive thereto in a range of movement along the track member.

A part 14 of the track member is provided with locking formations in the form of uniformly spaced windows or apertures therealong. The slider assembly 13 carries two locking members 15,16 of which the former is pivotally mounted to the slider assembly at 17 and the latter is pivotally mounted to the slider assembly at 18. The locking members 15,16 are somewhat of inverted U-shape in the illustrated view, and they extend in opposite directions (lengthwise of the track member 10) from their pivotal mountings to respective locking portions 19,20. Each of the locking portions comprises three teeth whose spacing corresponds to the spacing of the windows or apertures in the part 14 of the track 10, such teeth are indicated at 21 for the locking member 15. The teeth are able to engage with the windows or apertures in the track member 10 by entering same, and when this is done the slider assembly is locked against movement lengthwise of the track member.

The two locking members 15,16 are biased by respective springs 22, 23 to pivotal movement such that their respective teeth engage with the track member. The spacing between the locking portions 19,20 of the locking members is not an exact multiple of the spacing between the windows or apertures in the track member, so that when the teeth 21 of locking member 15 are able to engage with the track member as shown in the drawing, the teeth of the locking member 16 are not in alignment with apertures in the track member and thus cannot engage therewith. It will be appreciated, however, that on movement of the slider assembly relative to the track member by a suitable distance less-than the spacing between the apertures, the locking member 16 is able to engage with the track member. Thus the possibility of finer adjustment of the locked position of the seat is achieved.

A release lever 25 is pivotally mounted to the slider assembly at 26, and carries a transverse pin 27 which extends through aligned apertures in the two locking members 15,16. The release lever 25 extends to the front of the seat assembly where it is accessible to a person occupying the seat, and lifting the release lever causes, firstly, whichever one of the locking members is engaged with the apertures in the track member to be lifted out of such engagement and, subsequently, the other locking member to be pivoted so that its locking portion is lifted away from the part 14 of the track member.

It will be appreciated that if the seat should happen to be positioned such that neither locking member can have locking engagement with the track member, then whichever direction the seat is moved from such position, one or other of the locking members will engage the track member and prevent further such movement, even under conditions of high acceleration such as in a vehicle crash situation.

In a preferred modification of the embodiment above described, the pivotal mountings of the two locking members are spaced from one another by a substantially greater distance and the locking members extend towards one another therefrom. Then the locking portions of the locking members lie adjacent one another, so that for a given range of seat movement the track needs to be somewhat shooter than when it has to be engaged by widely spaced locking portions.

This modification is illustrated in Figure 2, which shows locking members 115,116 of the same general configuration as the locking members 15,16, the locking members 115,116 being pivoted to the slider assembly (not shown) at 117,118 respectively. The pivotal mountings of the locking members are remote from one another and the locking members extend towards one anòtherAheretrom so that the locking portions (119,120) of the locking members lie adjacent one another and indeed overlap one another. The locking members may be of metal plate, with their locking portions in face to face relationship with one another.

It will be noted that the teeth (121) of the locking member 115 are spaced lengthwise of the track member from the teeth of the locking member 116, in the manner described above to provide for the relatively fine adjustment of the locked position of the seat.

The locking members are movable together to disengage the teeth of whichever one engages the track by a lifting pin 127 which extends through aligned apertures in the two locking members.

The features disclosed in the foregoing description, or the following claims, or the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for attaining the disclosed result, as appropriate, may, separately, or in any combination of such features, be utilised for realising the invention in diverse forms thereof.