GB2252723A

GB2252723A - Motor vehicle seat

Info

Publication number: GB2252723A
Application number: GB9202322A
Authority: GB
Inventors: Hans Schneider; Thomas Dinges; Elmar Deegener; Volker Schaefer; Peter Bertenburg; Kurt Karschin
Original assignee: Keiper Recaro GmbH and Co
Current assignee: Keiper Recaro GmbH and Co
Priority date: 1991-02-15
Filing date: 1992-02-04
Publication date: 1992-08-19
Anticipated expiration: 2012-02-04
Also published as: JPH0777567B2; FR2672855B1; DE4104697C2; GB9202322D0; JPH0556824A; DE4104697A1; GB2252723B; FR2672855A1

Abstract

In a vehicle seat wherein the horizontal depth is variable by horizontally moving a section of the seat squab away from a fixed section of squab, means is provided to fill the gap left between the sections.

Description

2 2 5 2 "1. -z -J- A vehicle seat, particularly a motor vehicle seat Tne

invention relates to a vehicle seat, particularly a motor vehicle seat, with a variable seat depth and an at 1 e a s t substantially nonstretchable covering materi a] fDr the upholstery.

In the case of vehicl e seats of this type, it is known, i n order to i ncrease the seat depth, to shi f t a front portion of the seat cushion forwards, forming a gap from,.e rear part of the cushion on the seat part. It i S also known to provide between the front edge of the rear)ortion of the seat cushion and the rear edge of the front portion a covering material which is stretched and which covers the gap when the front part of the seat cushion is in the position of greatest seat depth. At settings of lesser seat depth, this covering material forms a crease which extends into the crack which is almost as disturbing as a g a p. It is true that suggestions have already been made to cover the gap with a covering m a t e r i a 1 which will stretch in the longitudinal direction of the seat. This solution does however pose problems because in the position of minimum seat depth a gap should be avoided but on the other hand the stretchable covering material cannot become correspondingly shortened.

2 - The invention is based on the problem of providing a v e h i c 1 e seat of vari abl e seat depth which does not suffer from the drawbacks of these prior art solutions. This proble-m is resolved by a vehicle seat having the features according to claim 1.

A gapl ess supporting surface at any adjustable seat depth can be achieved in various ways. For example, the at least suhstantially non-stretchable covering material used for the seat upholstery can be so extended beyond the rear portion thereof that there is no interrur)tion and the part of the covering material which extends forwardly beyond the rear portion of the seat upholstery - a n L, so rest on the front portion of the seat cushion 11hat this portion can still be displaced in the longitudinal direction of the seat while under the covering With a clamping device engaging the front end material. of the covering material, the covering material can be held taut in any selectable seat deoth setting.

Al so very advantageous is an embodiment in which at 1 east the front portion of the seat uDholstery is constructed as a deflectable layer of padding which at every selectable seat depth, is adjacent the rear portion of the seat upholstery without any gap extending therefrom forwardly to a deflecting means about which it is passed from the top downwardly. Al 1 that i s then required is for a displaceability of this deflecting means so that the top portion of the upholstery layer which is adjacent the rear portion of the seat upholstery can be lengthened or shortened by shortening or lengthening the portion which is passed around the deflecting means.

3 - lurthernore, i t i s for examDl e D o s s i b 1 e between the front and rear portions of the seat cushion to dispose an intermediate element which at any selectable seat depth setting can completely bridge the gap between the rear and front portions of the seat cushion. In the c a s e of a preferred embodiment, thi s intermediate element comprises at least one pair of crossing arms which have at their free end portions guide rollers o, which tie -mutually parallel pivot axes extend crosswise to tne seat. Passed around these guide rollers is e n d I e s s held by defined a n belt, of covering material lor example, which is the two upper rollers in the supporting surface by the t,.,jo portions of the seat cushion. When th ere is a change of seat d -9.D t h, the ang] e of the crossing arms is changed. When this happens, t.he length of the two Dortions of the endless belt which extend substantially at right-angles to the supporting surface of the seat part are shortened or lengthened to the same extent as that by w h i c h t, h e 1 ength of the portion 1 ocated, i n the seat suDporti ng surf ace i s 1 or shortened.

So that the e n d 1 e s s be] t h a s satisfactory SUDport, Dreferably at least two identically constructed pairs of crossing a -1ms are disposed ong b e s i d e the other and spaced apart in the transverse direction of the seat, t h -9 rol 1 ers extending from one p a i r of arins to the o t h e r.

It goes without saying that only that portion of the endless belt which is positioned in the region of the supporting surface need c o n s i s t of the covering materig]. Furthermore, the covering material may be backed by a layer of flexible padding in order to avoid a hard area in the suDporting surface.

Further advantageous developments of the intermediate element are the object of claims 6 and 7.

In the case of Vie embodiment with the deflectable layer of padding, there is advantageously on both sides of 11hi s layer of paddi ng and of the deflecting means a guide having a 1-1-shaped form, the uoper member of which mai ntai ns 'U e 1 aver of p a d d i n g i n the supporting surface. In tis g,iide there may be, crosswise to its longitudinal direction, a flexible stri p-l i ke padding carrier, preferably in the region of its two lateral longitudinal edges which is sufficiently flexurally rigid in the transverse direction of the seat to receive te loading occasioned by the bearing pressure of the upper member. To vary the seat deD.th, it is necessary only to shift t!ne deflecting means and the guide k-,jebs in the longitudinal direction of the seat. Advantageously, both guides are covered by lateral facings.

Advantageous further develoDments of the embodiment with ne covering material extending from the rear Dortion of the seat cushion and over the front portion to a clamping device are the oject of claims 12 to 18. The clamping device may for example comprise pivot levers which, as a function of the selected seat depth, defl-?ct to a greater or lesser degree tensioning belts or the like which are connected at one end to the front end of the covering material and at the other to the seat frame, and which therefore maintain the covering material taut. However, it is also for instance DOSsible - 5 f o r the cl ampi ng bel ts to be wound onto a s p i n d 1 e extending in the transverse direction of the seat and turning when there is a readjustment of the seat depth.

Examples of embodiment of the invention are explained in d e t a i 1 hereinafter with reference to the accompanying drawings, in which:

Fig. 1 shows an incomplete and diagrammatic longitudinal section through a first embodiment in the setting 1 for minimum seat deD-,,,:i; Fig. 2 is a cross-section 3ccording to Fig. 1 through the first embodiment set for maximum seat de)t;., Fig. 3 is an incomplete cross-section taken on the line III-III in Fig. 1; rig. 4 is an incomplete side view of a second example of embodiment; Fi g. 5 i s an i ncompl ete cross-secti on taken on the 1 i ne V-V in Fig. 4; Fig. 6 is an incomplete cross-seCtion taken on the line VI-VI in Fig. 4; 7 is an incomplete and diagrammatic longitudinal s e c t i o n through t h, e second embodiment set for minimum seat depth; Fig. 8 is a cross-section according to Fig. 7, set for maximum seat depth; Fig. 9 is a diagrammatic side view of a third example of embodiment; F i g. 10 is an incomplete view of the third example of embodiment from below, set for minimum seat deDth (right-hand half of the drawing) and for maximum seat depth (left-hand half of the drawing); F i g. 11 i S a cross -sect ion taken on the 1 i ne X I - X I i n Fig. 10; F i g. 12 shows a Cross-section taken on the line XII-MI in Fig. 10; F i g. 13 is a view from below of an example o." embodiment which is modified in comparison with that shown in Figs. 9 to 12; Fig.14 shows a cross-sec-tion taken on the line in Fig. 13, and FiQ.15 shows a cross-section taken on the line U-XV Fig. 13.

A motor vehicle seat of which a portion of the seat part is only shown diagrammatiCally, has a seat cushion subdivided in a transverse direction so that the seat deoth can lbe altered. The rear portion 1 of the seat cushion is carried by a rear cushion carrier which is not shown in greater detail ecause it is of known construction, which is in turn slioported by a seat frame, likewise not shown. Th e front portion 2 of the seat cushion is disposed on a front cushion carrier 3 which is fixed by the front end of two rods 4 which extend in the longitud i n a 1 d i r e c t i o n and whi ch are spaced apart from a n d adjacent one another in the transverse direction of the seat and which are mounted for longitudinal displacement in a respective housing 5 fixed on the seat frame. The rods 4 and the housing 5 could serve exclusively for guiding the front cushion carrier 3. The front cushion carrier 3 is then, for manual operation, preferably provided with a handle, for example at its bottom front the example of embodiment, itcan also be respective drive elements which may be pneumatically or manually actuated. By edge. In f o rim e d by electrically, means of these drive elements, the gap between the rear oortion 1 and the front portion 2 of the seat cushion can be adjusted as required for the desired denth of s e a t.

In order to arrive at a supporting area of a seat Dart in which there is no gap in the direction of adjustment, no matter which of the selectable seat deoths is chosen, tile supoorting area being defined by the top 11 of Vie rear portion 1 and the toQ 2' of the front portion 2 of til on seat c u s h i o n, a n i nterriedi ate e I ement generally desinated by the reference nurneral 6 is provided which, at any adjustable seat depth, completely bridges +.'Ie nao between the rear portion 1 and te front portion 2 of the seat cushion. This intermediate element comprises two e q u a 11 y constructed p a i r s of crossing arms 7 of e q u a I length which cross at half +.'qeir length, where they are pivotally mounted on a spindle 8 extending in Lle transverse direction of the seat. One pair of Vese arns 7 i s di sposed on one si de of te seat whi 1 e the other is disposed on the other side. Extending from the ends of one Dai r of arms 7, i n the transverse di recti on of the seat, is a roller 9 which extends to the corresponding ends of the other pair.

Passing over these four mutually parallel rollers 9 is an endless belt 10 of the covpring material also used for the rear portion 1 and the front Dortion 2, thi s coveri ng materi al possi bl y bei ng backed by a 1 i ni ng of thin padding. The 1 ength of the end] ess bel t 10 i s so chosen that it has as certain tension in a longitudinal direction and therefore also bears on the rollers 9 with a certain tension.

8 The s p i n d 1 e 11 carrying th e upper rear rol 1 er 9 i S mounted in two cover parts 12 of the seat structure 'isoosed on one side of the seat and on the other, its position being invariable in relation thereto, in fact so that the upper surface of the endless blelt 10 is always held by this roller 9 in the supporting area while the D-ortion of the endless belt 10 which extends d,D,.-inivardly from this roller 9 bears on the front end of the rear portion 1 of the seat cushion or is at most at a very short distance therefIrom. The other of the two,ipper rollers 9 is rotatably mounted on a spindle 13, ti-2 two end portions of which respectively engage slots 14 in the two cover parts 12 and extending in the direction of displacenent of the front portion 2 of the seat cushion. Also this roller holds the endless belt 10 in the supporting area and the portion extending d:)i,in,, .iardly from it is held to bear on tne front oortion 2 o f the seat c u s h i o n or at a very small distance t-.i-3r-2-Fron, as shown by Figs. 1 and 2. The spindle 13 Dasses throuQh the two slots 14 and is rotatably mounted in two facing parts 15 which cover the outside of the cover parts 12 and are rigidly connected to the front cushion carrier 3.

Starting from the position of minimum seat depth shown i n Fig. 1, i f thi s depth i s i ncreased, then the front Dorti on 2 of the seat cushion toqether with the front c u s h i o n carrier 3 is moved away from the rear Dortion 1 of the seat cushion, in other words leftwardly when looking in the direction according to Figs. 1 and 2. Since the two facing parts 15 are moved tociether with the frgnt Dortion 2 of the seat cushion, the position of the roller 9 carried by the spindle 13 does not alter in z - q - ela-ion to the fr 11 ont portion 2. In keeping with the increasing gap between the spindles 13 and 11, however, tne arms 7 are SDread apart more and more so that the listanCe between the two top and bottom rollers 9 on the one hand and the two rollers 9 on the other is increased o the same extent as that by which the gap between the spindles 11 and 13 is increased. Therefore, the endless ---elt 10 retains its tension.

As Fig. 2 shows, tnerefore, also the portion of the endless belt 10 which bridges the gap between the rear portion 1 and the front D.:)rtion 2 of the seat cushion remains taut and at any selected seat dep th it has i t S upDer surface in the suDporting area of the seat cushion so that this sup:)orting area extends without a gap from the front to t.e rear end of the seat cushion.

Instead of the spindle 13 engaging the slots 14, it is,,:)ssile as indicaIL-,ed by the dash-dotted lines in r'iis. 1 3nd 2, to provide slots 141 for the spindle 8 in the cover parts 12. Furthermore, instead of an adjusting drive which directly engages the front cushion carrier 3, it would be possible to provide a rotary drive which varies the angle at which the arms 7 cross each other. Thi s rotary d r i v e may be constructed for manual or ril.orised operation.

The example of embodiment of vehicle seat for a variable seat depth which is illustrated in F i g s. 4 to 8 has between side webs 20 of its seat part a cushion member 21 the thickness of which is sufficiently reduced in a front end portion 211 that here the cushion member 21 'orms a striplike layer of p a d d i n g which, in the example illustrated, is of constant thickness. In order to increase the deflectability of flexibility of this layer of padding, it is, as Figs. 7 and 8 show, Drovided wi th channel -1 i ke cavities 22 in the transverse direction of the seat.

The front end portion 211 of the cushion member 21 is on its under side rigidly connected to a flexible belt 23 w h i c h serves as a c u s h i o n carrier and which in the transverse direction of the seat offers sufficiently great flexural rigidity to accommodate the loadings which occur. In order to retain this flexural rigidity d e s p i t e consi deral e f 1 exi bi 1 i ty, it is possible to rovide eads which extend for example in the transverse direction of the seat.

The two lateral edges of the belt 23 respectively engage a guide groove 24. Each of the two guide grooves 24 is U-shaped, the two arms being superposed and extending in tne direction of seat deDth adjustment. Over a part of teir length, the guide grooves 24 extend in two cover parts 25 disoosed one on either side of the front end p)rtion 211 and rigidly connected to the seat structure qnd for the rest in two facing parts 26 which bear on the outside of one and other cover part 25 being guided for diSDlacement thereon in the direction of seat depth adjustment. In the example of embodiment, the facing parts 26 are for thi s purpose provided with a guide groove 261 which is open towards the cover part 25 and into which a guide strip 251 on the cover part 25 engages. The front portion of the two facing parts 26 which even at the minimum seat depth projects beyond the front end of the cover part 25 which carries it forms in each:ase a bearing web for a reversing roller 27 of 11 w h i c h the s p i n d 1 e 28 whi ch c a r r i e s i t i n r o t t i n g fashion is at both ends bolted to the facing part 26, as i S shown i n particular i n F i g. 5. Beari ng on t h i s reversing roller 27 is the belt 23 which in the region of this deflection is guided in a semi- circular portion of the two guide grooves 24.

At equal di stances f rom i ts ends, the reversi ng rol 1 er 27 comprises a break so that here one end of each rod 29 can!)e connected to the spindle 28. Tie two rods 29 extend in the di recti on of the mutual 1 y p a r a 11 e 1,ortions of the guide grooves 24 and are guided in each c a s e i n a h o u s i n g 30 r i g i d 1 y connected to the s e a t structure. As with the embodiment shown in Figs. 1 to 3, the rods 29 and the housings 30 can exercise what is Durely a guide function. In the example of embodiment, hoiever, they form an electrically, pneumatically or manually oDerable driving element.

On a basi s of the posi ti on f or mi ni rnuin seat deDt., i f this is increased, then diSDlacenent of the spindle 28 leftwardly, as vi ewed i n F i g s. 7 a n d 8, produces an extension of the nutually parallel portions of the guide grooves 24 in the direction of displacement, becuse the two f aci ng parts 26 are moved to the same degree in relation to the cover parts 25. The lateral edges of the ',)elt 23 therefore slide in the portions of the guide grooves 24 which are disposed in the facing parts 26,.ie bottom part of the front end portion 21 1 of the cushion member 21 being correspondingly shortened. Conversely, if there is a reduction in the seat deDth, this part becomes lengthened.

12 - Wh2re the example of embodiment shown in Figs. 9 to 12 is concerned and also with regard to the modified enbodiment according to Figs. 13 to 15 of a vehicle seat according to the invention, both the cushion carrier of tile seat part and also the seat cushion carried by it are divided in the transverse direction of the seat. The rear portion of the cushion carrier which is rigidly connected to the seat structure is generally designated 41 while the front portion is generally designated 42. The rear oortion 41 of the cushion carrier carries t'.he rear portion 43 of the seat cushion me-iber, the front lortion 42 carrying the front portion 44 of the seat cushion member.

Symmetrical 1 y in rel at ion to the 1 ongi tudi n a l central t 1 i ne through the rear Dorti on 41 of the cushi on carri er there are in this latter and extending in the direction of seat depth adjustment, two rigidly disposed g u i d e tu5es 45 in each of which a guide rod 466 is guided for longitudinal disD]acement. The front end portion of the two guide rods 46 which even with minimum seat deoth projects beyond the front end of the gui de tube 45 carries the front portion 42 of the seat cushion member. However, the guide rods 46 may also be rigidly connected to the rear portion 41 of the cushion carrier and the front portion 42 may be displaceable on the guide rods 46.

The rear portion 43 of the cushion mernber is covered with a covering material 47 but this does not, as in the case of known vehicle seats with a c u s h i o n member divided in order to adjust the seat depth, also cover the front end face of the rear portion 43 but, without 13 interruption, extends beyond the front portion 44 of the cushion member as shown in Figs. 11 and 12. Certainly, it would also be possible for the part of the covering material 47 which covers the front portion 44 of the cushion member to be connected by a seam or the like to the part which covers the rear portion 43 The areas the o f two portions 43 and 44 of the cushion member which are not covered by covering material 47 may be covered by a covering material, for example a thin woven fabric. Such a covering material can al so be provided on the supporting surface of the front portion 44 for the covering material 47 in order t_ o a v o i d abrasion of upholstery material and in order to ensure satisfactory sliding of the covering material 47 on the supporting surface of the front portion 44.

As Fig. 11 shows, in the position of minimum seat deoth, the covering material 47 extends over the front end of tne front oortion 44 of the cushion member and downwardly where it is passed around a deflecting member 48 on the front Dortion 42 of the cushion carrier. The deflecting member 48 is in the form of a strip extending in the transverse direction of the seat over the total width of the front portion 42 of the cushion carrier and which is rounded on its under side.

In the position of minimum seat depth, the covering material 47 ends at the inside of the deflecting member 48. Here, there are connected to the covering material 47 two strips 49, in fact in the case of the embodinent illustrated, they are disposed at a minimal distance from one or other of the lateral edges of the covering material 47. The two strips 49 are each passed over a resp-ctive deflecting means generally designated 50 to 'he rear -., )ortion 41 of the cushion carrier to which tneir other end is attached.

Each of the two identically constructed deflecting means 50 which are disposed on the outside adjacent to one and resoectively the other of the guide rods 46, COMDrise two identically constructed angled-over pivot levers 51 which are mounted close to the rear end of the front p3rtion 42 0 lc tne c u s h i o n carrier b y a spindle 52 ext.ending in the transverse direction of the seat and,V.Y,h. i: h is pivota.le in the front portion 42 0-117 the cushion carrier. In the examp] e of embodiment, the spindle 52 passes through the free end portion of one upwardly directed arm of the pivot lever 51. As Fig. 12 shows, the bearing point is disposed sonewhat above th e.uide rods 46. Between the two other arms of the pivot lever 51 which in the minimum seat depth position extend obliquely forwardly and upwardly there is in the region between the free ends a deflecting roller 53 having an axis of rotation extending in the transverse direction of the seat and which projects into the path of one strip 49. Accordingly, the deflecting roller 53 of the other pair of pivot levers projects into the path of the Other strip 49. After deflection by the roller 53, the strip 49 extends between the pivot levers 51 towards their downwardly pointing end and there it extends along the under side of a deflecting web 54 disposed between the t "At 0 pivot levers 51 rearwardly to the point of attachment on the rear portion 41 of the cushion carrier.

Z The bottom end portion of the two pivot levers 51 of each pair is provided with a slot 55 extending approximately vertically in the position of minimum seat depth and the said slot 55 accommodates a pin 56 extending in the transverse direction of the seat. As Fig. 10 shows, the two pins 56 are lengthened outwardly as far as a cushion carrier carrying a respective side web 57 which is rigidly connected to the seat frame and which therefore does not move in relation to the rear portion 41 of the cushion carrier when there is a variation in seat depth. If the front portion 42 of the cushion carrier is moved away fron the rear portion 41, then the spindle 52 moves in relation to the pin 56 in the longitudinal direction of the guide rods 46. The pivot levers 51 of the two deflecting means 50 which are connected to each other in rotationally r i g i d f a s h i o n by tne resistant spindle 52, are therefore pivoted in cl ockwi se di recti on as seen i n F i g. 11 ' th e between the pi n 56 and tile sDi ndl e 52 bei ng i whi 7-h i s a] 1 owed bv the s] ot 55 t o r s i o n an anti di stance ncreased, This pivoting movement i n an anti -,-1 ockwi se di recti on as seen i n Fi g. 11 wi 11, as F i g. 12 shows, 1 ead to the def 1 ecti ng rol 1 ers 53 'eing moved downwardly on a circular path about the axis 52, diminishing the deflection of the two strips 410 by the amount by which the distance between the front and rear portions of the cushion carrier is increased. The covering materi a] 47 which upon a displacement of the front portion 44 of the cushion member away from the rear portion 43 slides over the front portion therefore remains taut. Therefore, the gap between the t w 0 portions of the c u s h i o n member does not become apparent.

16 If the seat depth is reduced, then the two pivot levers 51 of each deflecting means 50 are pivoted in a clockwise direction as viewed in Figs. 11 and 12, resulting in the front end of the covering material 47 being drawn downwardly towards the deflecting member 48 and then around it and upwardly.

Instead of a pivoiling of the pivot lever 51 by means of th e p i n 50, the gui de rods 46 coul d al so be freel y disposed in the front portion 42 of the cushion carrier and be provided with teeth in the form of a toothed rack engaged by a gearwheel rotationally rigidly disposed on + L.

---hespindle 52. Certainly, furthermore, the guide rods 46 would need to be rigidly connected to the rear Dortion 41 of the cushion carrier so that upon a displacement of the front portion 42, the gearwheel would roll along the teeth in the guide rail 46.

In the case of the modified embodiment shown in Figs. 13 to 15, which is modified in relation to Figs. 9 to 12, the two gui de rods 46 are constructed i n thi s way, 1 n other words they are r i a i d 1 y connected to the rear portion 41 of the cushion carrier.

The front oortion 42 is displaceably mounted on the two guide rods 46 which in the portion projecting into the front part 42 of the cushion carrier are provided on tnei r under side with teeth in the form of a toothed r a c k. These two toothed racks are engaged by gearwheel s, not shown, which are rotationally rigid on a llorsion resistant shaft 58 mounted for rotation in the front portion 42 of the cushion carrier, the said shaft 58 extending in the transverse direction of the seat.

h "h of the The two end Dortions which project into the pall strips 49 and which are fixed at one end on the front Rnd of the covering material 47 and at the other on the rear portion 41 of the cushion carrier are provided, passing in a radial direction through the shaft 58, with a slot 59 through which the strip 49 is passed.

In the maximum seat depth position, the two slots 59 in the s h a f t 58 extend so that the stri DS 49 are 0 n 1 y slightly angled over, as shown in Fig. 15. If the seat de,Dth is reduced, then the shaft 58 rotates a. bout its longitudinal axis so that the strips 419 are wound somewhat farther onto the shaft 58, as indicated in Fig. 14 for the minimum seat depth position. As in the case of toe example of embodiment according to Figs. 9 to 12, therefore, the covering material 47 which is able to slide over the front portion 44 of the cushion member, is maintained taut so that the gap which, with increased s e al-, deDth, is present between the f r o n t and rear Dortions of the cushion member, i s bridged in invisible manner.

Instead of the shaft 58 being driven by the gearwheels, it is natural] y a] so possi bl e to provide for drive by mean.s of a pivot lever which cooDerates with a pin as in the case of the embodiment shown in Figs. 9 to 12.

All the features mentioned in the foregoing description and those which can be ascertained purely from the drawings are to be regarded as further develODments and are constituent parts of the invention even if they have n3t been particularly stressed and in particular if they have not been mentioned in the claims.

A

Claims

1. A vehi cl e seat, parti cul arl y a motor vehi cl e seat, wi th a v a r i a b 1 e seat depth and an at 1 east substantially non-stretchable covering material for the upholstery, characterised by the seat user being offered a gap-free supporting area on the seat part in the direction of adjustment at any selectable seat depth.

2. A vehicle seat according to claim 1, characterised in that the cushion of the seat part is sub-divided into a rear portion (43) and a front portion (44) adapted for displacement relative thereto in the direction of adjustment and in that the covering material (47) which rests on the top of the front portion (44) of the cushion member and which is displaceable in the direction of adjustment extends from the front end of the rear portion (43) of the cushion member over the front portion (44) and to a tensioning device (50, 58, 59).

3. A vehicle seat according to claim 1, characterised in that at least a front portion (211) of the seat cushion (21) is constructed as a deflectable layer of padding which at any selectable seat depth extends forwardly from the rear portion of the seat cushion 1 an d i 5 passed f rom the top downwardly around a deflecting means (27, 28) which is displaceable in the direction of adjustment and which forms the front end of the cushion carrier.

4. A vehicle seat according to claim 1, characterised in that the cushion on the seat part is sub-divided into a rear portion (1) and a front portion (2) adapted for displaCement relative thereto and in the direction of adjustment, b) at any selectable seat depth the i nterinedi atle space between the tiwo portions (1, 2) of the seat cushion is completely bridged by an intermediate element (6) having an endlessly constructed belt,10) which is passed around guide rollers (9), c) tne guide rollers (9) are provided on at least one pair of intersecting arms (7) which at the point of intersection are connected to one another and are able to pivot about an axis (8) which, like the axis of rotation of the guide rollers (9) extends in the transverse direction of the seat, d) the rollers (9) provided at one end of each of the two arms, at any sel ectabl e angul ar position of the arms (7) within the range of depth adjustment, maintain the top of the endless belt (10) in the supporting area defined by the two portions (1, 2) of the seat cushion.

a) 5. A vehicle seat according to claim 4, characterised in that at least two identically constructed pairs of crossing arms (7) are disposed beside and at a - 20 distance from each other in the transverse direction of the seat and in that the rollers (9) extend from one pair of arms to the next.

A vehicle seat according to claim 4 or 5, charac terised in that one of the rollers (9) which maintain the top of the endless belt (10) in the supporting area is incapable of changing its p o s i t i o n in rel ati on to the rear porti on ( 1) of the seat clishi on and in that either the axis of the other roller (9) which maintains the top of the endless helt (10) in the supporting area or the spindle which connects the Lwo arms (7) in pivotable fashion is guided for displacement along a path (14, 141) crosswise to its longitudinal direction.

7. A vehicle seat according to claim 6, chara-_terised in that the guideway (14) is formed by a slot into which protrudes an end portion of the spindle carrying the roller (9) or the spindle which pivotally connects the arn.s (7).

8. A vehicle seat according to claim 3, characterised in that on both s i d e s of the deflectable layer of p a d d i n g (211) and the deflecting means (27, 28), there is a respective U-shaped guideway (24) of which the part forming the leg of the U maintains the top of a portion of the deflectable padding layer (211) in the supporting area of the seat cushion while its part which forms the other leg of the U is underneath the other leg.

A vehicle seat according to claim 8, characterised in that a striD-like carrier (23) flexible crosswise to its length and on which the deflectable layer of padding (211) is supported is guided in the guideways (24), preferably in the r e 9 i o n of i t S two lateral longitudinal edges.

10. A vehicle seat according to claim 8 or 9, characteri sed in that the deflecting means consists of a rotatably nounted roller (27) extending in the transverse direction of the seat.

A vehicle seat according to one of claims 8 to 10, characterised by a drive device (29, 30) for disp] acement of the deflecting means (27, 28) and of the gui deways (24) i n the di recti on of seat deoth adjust-ment.

A velhi cl e seat accordi ng to cl ai m 2, characteri sed i n that the tensioning devi ce has at 1 e a s t one elongate traction element (49) the two ends of which are connected to the covering material (47) and the seat structure (41) supporting the rear portion (43) of the seat cushion and in that a deflecting device (51, 53) is provided for the traction element (49), deflecting this latter as a function of the selected seat depth, to an extent which maintains the covering material (47) taut.

13. A vehicle seat according to claim 12, characterised in that the deflecting means has at 1 e a s t one deflecting 1 e v e r (51 adapted to pivot about a spindle (52) extending in the transverse direction o f the seat and th e pi voted p o s i t i o n of which, determining the degree of deflection, varies with the displacement of the front portion (42) of the seat cushion carrier.

14. A vehicle seat according to claim 13, characterised in that at a distance from its pivot spindle (52), the deflecting lever (51) has a guide slot (55) into which projects a journal (56) which is parallel with its spindle (52) and which is rigidly connected to -I- Llhe seat structure carrying the rear portion (43) of the seat cushion.

according to claim 13, characterised 15. A vehicle seat in that -,',he deflecting lever (51) has as a pivoting drive a gearwheel which is rotationally rigidly connected to it and a rack which meshes therewith and extends in the direction of displacement.

A vehicle seat according to claim 12, charlacterised in that the tensioning device h a s at 1 east one elongate traction element (49), the two ends of which are connected to the covering material (47) or the seat structure supporting the rear portion of the seat cushion and comprising for the tensioning element (49) a take-up roller (58) which rotates at a function of the displacement of the front portion (42) i n rel ati on to the rear Porti on (41) of the cushion support and which, extending in the transverse direction of the seat, is rotatably mounted on that part of the seat structure which suDports the front portion (44) of the seat cushion.

a b 17. A vehicle seat according to claim 16, characterised in that the take- up roller (58) is provided with a radial slot (59) through which the traction element (49) is passed.

18. A vehicle seat according to claim 16 or 17, charac terised in that the take-up roller (58) is rotationally rigidly connected to a gearwheel which meshes with a rack extending in the direction of displacement.