GB2107179A

GB2107179A - Sliding rail device, particularly for adjusting motor-vehicle seats in position longitudinally

Info

Publication number: GB2107179A
Application number: GB08229871A
Authority: GB
Inventors: Heinz Bauer; Burckhard Becker; Ernst-Reiner Frohnhaus; Alfred Gedig
Original assignee: C Rob Hammerstein GmbH
Current assignee: Johnson Controls Metals and Mechanisms GmbH and Co KG
Priority date: 1981-10-20
Filing date: 1982-10-19
Publication date: 1983-04-27
Also published as: FR2514702B1; SE8205925D0; GB2107179B; DE8130557U1; DE3238028A1; DE3238028C2; SE8205925L; SE448157B; FR2514702A1

Abstract

The sliding rail device has an outer rail (20) enveloping an inner rail (21). The inner rail has a U-shaped structure (22). The outer rail has at least an L-shaped structure (27, 28), but preferably also has a U-shaped structure (33, 34, 35) and also has a C-shaped structure (29) which envelops the base portion (25) of the inner rail. Balls, dumbells or rollers, acting as sliding means, are interposed between the rails, some of the balls or rollers (36, 37) being situated in an outer channel (30) between the C-shaped structure (29) of the outer rail (20) and the base portion (25) of the inner rail (21), others (38) of the balls or rollers being situated in an inner channel (31) between the base portion (25) of the inner rail (21) and a track-web (34) of the outer rail (20). <IMAGE>

Description

SPECIFICATION Sliding rail device, particularly for adjusting motor-vehicle seats in position longitudinally The invention relates to a sliding rail device, particularly for adjusting motor-vehicle seats in position longitudinally, with, as seen in cross section, an outer rail enveloping an inner rail, the two rails sliding along relative to each other; the inner rail having a U-shaped structure comprising two webs joined together by a base-portion, the outer rail having at least an L-shaped structure comprising an outer web and a base-portion, but preferably also having a U-shaped structure with an inner web joined to the base-portion; the outer rail also having a C-shaped structure joined to its outer web and enveloping the base-portion of the inner rail; sliding means being interposed between the two rails; some of the sliding means being situated in an outer channel between the baseportion of the inner rail and the C-shaped structure of the outer rail, these sliding means being balls or rollers; others of the sliding means being interposed in an inner channel situated within the base-portion of the inner rail.

This arrangement, known from the German Patent Specification 27 02 576, has proved very effective in practice, partly because the system of rails has a generous height, as seen in cross section, and is therefore very stiff against vertical stresses, and partly because the double envelopment, arranged so that the two rails engage hookwise, with each other, effectively prevents the rails from separating from each other.

The known arrangement is therefore suitable where a safety belt is attached to the seat. Due to its success in practice this arrangement has been developed further, compare for example the German Offenlegungsschrift 25 45 763, also 2806998 and 2832519.

The known sliding rail device has a strip of elastomer, for example rubber, attached to the narrow inner web of one of the two rails, the strip of elastomer being embraced by a shoe made of a friction-resistant material. The outer surface of the shoe rests in contact with the inner surface of the base-portion of the other rail. The strip of elastomer is normally in a squashed-together state and ensures that, by its elastic behaviour, the two rails do not chatter against each other when there is no load, i.e. the elastomer takes up the slack between the two rails. The shoe protects the elastomer from abrasion and encloses the edges of the inner web.

But the sliding movement of the rails is impeded by friction, i.e. they do not slide freely. The friction is greatest when there is no load, i.e. when there is no passenger on the seat. Bu there is still considerable friction when a passenger load is applied. The weight of the passenger increases the gap between the free end of the inner web and the inner surface of the base-portion, but this hardly reduces friction. Furthermore the shoe, which is made of comparatively thin metal, gradually adapts its shape to local deformation of the baseportion of the rail, so that the shoe becomes deformed. Finally, the inner surface of the baseportion, which is not always quite smooth, in time suffers a certain amount of abrasion and this reduces the accuracy of the sliding movement.

From the German Offenlegungsschrift 30 30 765 a sliding rail device is known in which both rails have U-shaped structures which hook into each other. In this known device the two rails slide along each other with the help of balls or rollers, and therefore with little friction. But there is no enveloping C-structure and the balls or rollers roll on the side-walls of the webs.

The intention in the present invention is to improve the known sliding rail devices so as to reduce friction in the sliding movement, and so as to ensure that the low friction endures over a long working life.

The problem is solved in that balls or rollers, for serving as the sliding means, are interposed in the inner channel within the base-portion of the inner rail, the outer rail having a track-web; the trackweb extending approximately perpendicular to the outer web and the terminal flange of the inner rail, and to the outer web and the foot-web of the outer rail; the track-web being situated opposite the base-portion of the inner rail; the track-web providing a track, particularly a track-groove for the ball or roller.

Thus in the sliding rail device of the present invention the sliding means do not thrust against the very narrow edge (whose width is only the thickness of the strip material) of the free end of the inner web of the rail, but thrust against the surface of a track-web, the sliding means being balls or rollers. Consequently the friction encountered when the rails slide is entirely rolling friction and this is very low irrespective of whether a load is applied or not. Furthermore the low friction ensures over a long working life. As the balls or rollers are usually harder than the strip of which the rails are made, they tend to roll the strip surface smoother.

In the sliding rail device of the invention chattering of the rails against each other is prevented in a weil-controlled and enduring manner. Instead of using an extra strip of elastomer to take up the slack between the rails, the elastic resilience of the strip material of the outer rail is utilised. The outer rail is pre-stressed where it envelopes the inner rail, the pre-stressing being accurately adjustable. In particular the position of the track-web is easily adjustable, relative to the remainder of the cross-sectional profile of the outer rail, the cross-sectional configuration providing sufficiently wide adjustment to compensate for quite large deformations and tolerances.

The tear-apart strength of the sliding rail device of the invention can be made particularly great by giving each rail a single U-shaped structure, each rail enveloping the other. The track-web can be made to contribute considerably to tear-apart strength by making the track-web of the outer rail extend perpendicular to its foot-web and in the opposite direction to its base-portion. The trackweb therefore also acts as a claw, helping to prevent the U-shaped structure from opening up.

Alternatively, if the track-web of the outer rail is joined directly to its base-portion, forming approximately a straight-line continuation of the base-portion, a very practical configuration is obtained which is easy to manufacture and can be conveniently pre-stressed.

With advantage, one of the channels can contain two rows of balls disposed next to each other. The centres of the balls therefore form a triangle, so that the device takes side loads better.

Alternatively, at least one of the channels can contain compartively wide rollers, dumbbells or the like, or rollers rolling on neighbouring tracks.

Conveniently the other side of the track-web, opposite the track-groove, can provide a space for accommodating a locking device.

And there can be a region, situated where the track-web merges into the foot-web or into the base-portion of the outer rail, where the metal strip is thinner. This makes it possible to utilise the resulting resilience of the track-web for adjustment of pre-stressing within wide limits, without it being necessary for other regions of the configuration of the outer rail to flex to any great extent.

With advantage the balls or rollers in the two channels are disposed symmetrically on either side of a middle plane which passes through the middle of the base-portion of the inner rail and extends parallel to the outer web and the terminal flange of the inner rail and to the outer web and the foot web of the outer rail. The arrangement ensures that the loads applied to the sliding rail device, particularly the weight of a passenger, are taken well because the loads are transmitted vertically, without lateral components, from the outer rail to the inner rail.

Further advantages of the invention are described in the remaining claims.

The invention will now be described in greater detail with the help of the examples shown as cross sections in the drawing, in which: Figure 1 is a cross section showing an example in which both rails envelop each other with the help of U-shaped structures.

Figure 2 is iargely similar to Figure 1.

Figure 3 shows an example which is narrower but in which both rails still envelop each other Figure 4 shows an example in which only the one rail envelops the other.

Figure 5 shows an example with a cylindrical roller, and here again both rails envelop each other.

Figure 6 shows a largely similar example, but in this case only the one rail envelops the other.

The sliding rails devices shown in ail the figures are particularly suitable for fore-and-aft adjustment of the seats in motor-vehicles. Each device comprises an outer rail 20 which envelops, as seen in cross section, an inner rail 21, the two rails sliding along each other. Either of the rails can be attached to the floor of the vehicle, the other being attached to the seat.

The figures show cross sections of several different examples of the invention. All the examples have this in common, that the inner rail 21 has a U-shaped structure 22 (compare Figure 1). If this is followed along, starting from the outer web 23 and moving towards the terminal flange 24, the U-shaped structure 22 of the inner rail 21 comprises, first, an outer web 23, then a baseportion 25 and finally the terminal flange 24. The outer rail 20 is more complex in configuration.

Starting from an outer web 27, the lower portion of this rail comprises (as seen in cross-section) an L-shaped structure consisting of the outer web 27, a base-portion 28, a foot-web 33, a track-web 34.and a terminal flange 35. The upper portion of the outer rail 20 comprises, starting from the outer web 27, a C-shaped structure 29 which envelops, or goes around, the base-portion 25 of the inner rail 21. Between the C-shaped structure 29 and the base-portion 25 there is an outer channel 30 for accommodating balls 36,37 or the like.

Below the base-portion 25 there is a second channel 31 for accommodating further balls 38 or the like.

A characteristic feature of the sliding rail device according to the invention is that the balls or the like are situated symmetrically on either side of a middle plane 32 which bisects the base-portion 25 of the inner rail 21 and is parallel to the outer web 23 of the inner rail 21, its terminal flange 24 and the outer web 27 of the outer rail 20. By this arrangement the two rails 20, 21 are supported against each other at three points although, if desired, a 4-point support can be provided. The 3point support also takes sideways thrusts, and this without impairing the easy fore-and-aft movement of the rails.

In Figure 1 the lower portion of the outer rail 20, starting from the foot-web 33 of the Uhaped structure here, is extended by the track-web 34 to terminate in the terminal flange 35, and it will be observed that the track-web 34 runs parallel to the base 29 of the C-shaped structure of the upper portion of the rail. The terminal flange 35 of the lower portion of the outer rail 20 extends downwards parallel to the outer web 23 of the inner rail 21. Between the track-web 34 and the base-portion 25 of the inner rail 21 there is an inner channel 31 for accommodating a ball or the like 38.

Still referring to Figure 1, it will be seen that the two balls 36, 37 are situated on either side of the roof-shaped crown of the base portion 25 of the inner rail 21. And it should be understood that behind the three balls shown in the cross section there are other balls distributed along the rails.

The two balls 36 and 37 in the outer channel 30 are spaced fairly far apart, the gap between them being about one ball diameter in width. The two balls 36, 37 are retained in a ball-cage 39. In contrast to this, the ball 38 in the inner channel 31 is situated in the middle plane 32, and its diameter is less. The arrangement ensures that a good rolling movement is obtained. The triangular configuration of the ball centres ensures that both vertical and horizontal loads are well taken.

The outer rail 20 is fairly flexible, so that it acts .as a spring-clamp, resiliently thrusting the two balls 36, 37 against the flanks of the base-portion 25 of the inner rail 21. This prevents the sliding rail device from chattering, even when it is not carrying a load. The resilient pre-stressing can easily be adjusted over a wide range, the configuration of the cross section favouring resiliency.

The terminal flange 35 of the inner rail 21 facilitates the hook-like engagement of the two rails with each other. Furthermore, the terminal flange 35 can, if desired, have notches to take the nose of a locking lever (not shown) for lucking the seat in place.

An important point is that there are only small air gaps between the U-shaped structure 22 and the webs 27 and 33, so as to give the sliding rail device a good tear-apart strength. If desired, the outer web 27 can have a step in the plane 32 below the lower end of the terminal flange 35. If the step has notches in it and the terminal flange 35 has teeth, this increases the tear apart strength of the sliding rail device shown in Figure 1, in that when the rails 20, 21 move apart from each other the teeth engage in the notches, preventing further separation of the rails. The teeth are not normally engaged with the notches and therefore do not interfere with the movements of the rails.

Under the track-web 34 there is a space 40 which can be used, for example, for accommodating a locking device.

The outer web 27 has an inwards step 41 to increase the distance between the balls 36, 37 and the allow larger balls to be used, and also to reduce the air gap between the outer web 27 of the outer rail 20 and the terminal flange 24 of the inner rail 21. Alternatively, the terminal flange 24 can have an outwards step.

The upper surface of the base-portion 25 has grooves to act as tracks for the balls 36, 37 and the track-web 34 has a groove 42 for the ball 38.

The base-portion 25 has a raised crown to provide a track for the ball 38.

The example shown in Figure 2 corresponds largely to the example of Figure 1, but without the terminal flange 35. Furthermore, the example of Figure 2 has a region 43 where the foot-web 33 merges into the track-web 34 and where the metal strip is of reduced thickness. This allows the resilient pre-stressing of the outer rail 20 to be precisely adjusted.

In the examples of Figures 3 and 4 the two upper balls 36 and 37 have been brought close together so that they almost touch. This makes the device narrower. In Figure 3 the lower ball 38 has only about half the diameter of the upper balls 36, 37. The upper balls 36, 37 have to be large enough to take the weight of the driver or passenger and still give the sliding rail device an easy movement. The lower ball facilitates the sliding movement when there is no load. The outer web 23 of the lower rail 21 can have openings 43 for a locking mechanism (not shown).

The example of Figure 4 has no double envelopment as described for the sliding rail system of the German Offenlegungsschrift 27 02 576. The lower base-portion 28 of the outer rail 20 merges directly into the track-web 34, i.e. the outer rail 20 merely has a lower L-shaped structure 26, rather than a U-shaped structure. Apart from that, the example of Figure 4 is largely similar to the example of Figure 3.

Nevertheless it will be observed that in the example of Figure 4 all three balls have the same diameter and consequently the centres of the balls form a narrower triangle. The triangle formed in Figure 3 is approximately equilateral.

Each of the examples of Figures 5 and 6 contains a roller 45 in the outer channel 30.

Consequently the upper surface of the base portion 25 of the lower rail 21 is flat, to provide a rolling surface for the roller 45.

The example of Figure 5 has double envelopment. The foot-web directly to 9 curved double track-web 34 which has, in its upper surface, two track-grooves 42 for two balls 38 of comparactively small size. The two balls 38 are of the same size and are situated next to each other.

Particularly in the example of Figure 5, but also in the other examples, a problem arises in ensuring that when the sliding rail device is not loaded the two upper balls, and in Figure 5 the two lower balls, rest evenly and in good alignment in contact with their track surfaces. This can be obtained by suitably adjusting the geometry of the cross section. The outer rails 20 forms a substantially C-shaped clamp whose two ends rotate, during the flexing of the clamp, about a neutral line which does not itself move. If the neutral line is at eactly the same height as the middle of the base portion 25 of the inner rail 21, pre-stressing of the rail involves no lateral thrusts.

The comparatively simple example shown in Figure 6 also contains a cylindrical roller 45 in the outer channel 30. The inner channel 31 contains a comparatively large ball 38. This examples does not provide double envelopment. The cylindrical roller 45 in the outer chamber 30 provides triangular 3-point support without it being necessary to use a double row of balls.

Claims

1. A sliding rail device, particularly for adjusting motor-vehicle seats in position longitudinally, with, as seen in cross section, an outer rail enveloping an inner rail, the two rails sliding along relative to each other; - the inner rail having a U-shaped structure comprising two webs joined together by a baseportion; the outer rail having at least an L-shaped structure comprising an outer web and a baseportion, but preferably also having a U-shaped structure with an inner web joined to the baseportion; -the outer rail also having a C-shaped structure joined to its outer web and enveloping the base-portion of the inner rail; - sliding means being interposed between the two rails; - some of the sliding means being situated in an outer channel between the base -portion of the inner rail and the C-shaped structure of the outer rail, these sliding means being balls or rollers;; pothers of the sliding means being interposed in an inner channel situated within the baseportion of the inner rail, characterised in that balls (38) or rollers, serving as the sliding means, are interposed in the inner channel (31) within the base-portion (25) of the inner rail (21), the outer rail (20) having a track-web (34); -the track-web (34) extending approximately perpendicular to the outer web (23) and the terminal flange (24) of the inner rail (21) and to the outer web (27) and the foot-web (33) of the outer rail (20); -the track-web (34) being situated opposite the base-portion (25) of the inner rail (21); -the track-web (34) providing a track, particularly a track-groove (42) for the ball or roller (38).

2. Sliding rail device as claimed in Claim 1, in which the outer rail has a U-shaped structure and in which the end of each rail, as seen in cross section, penetrates into the U-shaped structure of the other rail, characterised in that the track-web (34) of the outer rail (20) extends perpendicular to its foot-web (33) and in the opposite direction to its base-portion (28) (Figures 1, 2, 3 and 5).

3. Sliding rail device as claimed in Claim 1, characterised in that the track-web (34) of the outer rail (20) is joined directly to its base-portion (28), the track-web (34) forming approximately a straight-line continuation of the base-portion (28) (Figures 4 and 6).

4. Sliding rail device as claimed in one of claims 1 to 3, characterised in that one of the channels (30, 31) contains two rows of balls disposed next to each other.

5. Sliding rail device as claimed in one of the Claims 1 to 4, characterised in that one of the channels (30,31) contains rollers, dumbbells or the like.

6. Sliding rail device as claimed in one of the Claims 1 to 5, characterised in that on the other side of the track-web (34), opposite the trackgroove (42), there is a space (40) for accommodating a locking device.

7. Sliding rail device as claimed in one of the Claims 1 to 6, characterised in that a region (43) where the metal strip is thinner is situated where the track-web (34) merges into the foot-web (33) or into the base-portion (28) of the outer rail (20).

8. Sliding rail device as claimed in one of the Claims 1 to 7, characterised in that the balls or rollers in the two channels (30, 31) are disposed symmetrically on either side of a middle plane (32) which passes through the middle of the base portion (25) of the inner rail (21) and extends parallel to the outer web (23) and the terminal flange (24) of the inner rail (21) and to the outer web (27) and the foot-web (33) of the outer rail (20).

9. Sliding rail device as claimed in one of the Claims 1 to 8, characterised in that the outer rail (20) is elastically flexible and is pre-stressed so as to thrust the balls or rollers in each channel (30, 31) against the base-portion (25) of the inner rail (21).

10. Sliding rail device as claimed in one of the Claims 1 to 9, characterised in that one of the rails (such as 21) has teeth, the other rail (in this case 20) having notches which engage with the teeth when the rails move to separate from each other, the teeth not engaging with the notches under normal circumstances.

11. A sliding rail device, substantially as hereinbefore described with reference to any one of the accompanying drawings.