Seat arrangement

A sitting and/or lying arrangement, particularly a vehicle seat or airplane seat, has a stable subframe and a flexible support which has a base part and a cushion. For creating such an arrangement, in which the user's body is anatomically correctly supported such that the body can relax and no pressure points are formed, the base part consists of a transversely stiff but longitudinally flexible material and is implemented, for example, by a thin, corrugated spring plate made of spring steel, carbon fibers, glass fibers or kevlar fibers, titanium and the like.

BACKGROUND AND SUMMARY OF THE INVENTION
 This application claims the priority of German application 198 28 254.0,
 filed Jun. 25, 1998 in Germany, the disclosure of which is expressly
 incorporated by reference herein.
 The invention relates to a sitting and/or lying arrangement, particularly a
 seat such as a vehicle seat or airplane seat of the type having a stable
 subframe comprising a seat frame of a seat part and a backrest frame of a
 backrest connected therewith, and having a base part which has a
 transversely stiff and longitudinally flexible construction,.
 In the case of a known seat for vehicles or the like (German Patent
 Document DE 22 09 744 A1), the subframe has a forward, a rearward and two
 lateral frame parts, and a flexible or elastic base plate or bottom plate
 is connected to one or several of these frame parts, while it is separated
 from all the other parts of the frame and is connected with these by way
 of elastic elements, such as coil springs. In one embodiment of this seat,
 the elastic elements are constructed as corrugated and therefore
 correspondingly flexible sections of the bottom plate, so that a downward
 directed pressure admission as the result of the sitting person's weight
 causes a pressing-down of the two flexible sections and a deflection of
 the bottom plate in the downward direction. The cushion, which is made,
 for example, of foamed urethane rubber, is mounted on the frame, the frame
 and the cushion being covered by means of a casing made, for example, of
 vinyl leather.
 Such a seat has the disadvantage that the cushion is too thick and will
 wear out after being subjected to a prolonged load. A proper resistance to
 the anatomic structure of the body required for a correct sitting is not
 ensured. One also does not sit in a two-point sitting position on the
 ischial tuberosities, which exist for this purpose, but slides onto the
 tip of the coccyx and sits in a so-called three-point sitting position,
 which is extremely uncomfortable. The result is the constant desire to
 change the body position in the seat, which, in the case of an automobile
 seat, may result in the lack of attention to traffic, a feeling of
 uneasiness and rapid fatigue as well as irritability. In the case of an
 airplane seat, this leads to a disturbing sitting sensation, pain in the
 area of the spinal column and to a lack of sleep during long flights so
 that the body cannot rest during the flight and considerable fatigue
 occurs at the destination. In the case of sick persons with, for example,
 neuropathic changes, such a three-point sitting position may result in a
 pressure sore; in the case of wounds of other origins, for example burns,
 it may result in wound healing impairments.
 In the case of a known backrest with a backrest frame, a cushion and a back
 shell for a motor vehicle seat (German Patent Document DE 35 15 631 A1), a
 simple construction with a low installation depth is achieved in that the
 back shell covered toward the front by the cushion has an elastic
 transition area used for the fastening on the backrest frame and an
 elastic transition area which follows toward the flat center part, which
 transition area preferably has a profile which has a corrugated
 cross-section and permits a resilient movement of the center part
 perpendicularly to the main plane of the backrest.
 In the case of a known sitting or lying arrangement of the initially
 mentioned type (German Patent Document DE 24 00 119 A1), the base part
 fastened by means of its forward and rearward end on the seat frame is a
 mat made of a resilient material which is essentially non-ductile per se,
 such as spring steel plate, which obtains its flexibility in the
 longitudinal direction by extensional corrugations which are made
 transversely to the longitudinal direction and at an equal distance from
 one another. The extensional corrugations have a V-shaped or U-shaped
 profile and are shaped in one piece out of the spring plate in such a
 manner that their V- or U-openings point upwards. When the mat is loaded
 by a sitting person, the opening width of the extensional corrugations is
 enlarged and therefore permits an extension of the mat in the longitudinal
 direction. Another mat is mounted in the backrest frame, in which case end
 edges of the mat extending in parallel to the extensional corrugations are
 fixed on the two vertically extending spans of the backrest frame.
 It is an object of the invention to construct a sitting and/or lying
 arrangement of the initially mentioned type in the case of which the
 user's body is supported in an anatomically correct manner such that the
 body can relax and no pressure points occur.
 According to the invention, this object is achieved by providing an
 arrangement of the above referred to general type, wherein the base part
 is formed of a thin corrugated spring plate whose corrugations extend
 transversely and spaced from one another in a longitudinal corrugation
 direction of the seat, and which is suspended by means of a forward end
 edge, which extends transversely, on a forward cross strut of the seat
 frame and is suspended by means of a rearward end edge, which extends
 transversely, on an upper transverse spar of the backrest frame, and
 wherein a cushion rests on the corrugated spring plate, which cushion is
 divided into a section forming a seat cushion and into a section forming a
 backrest cushion.
 The sitting and/or lying arrangement according to the invention has the
 advantage that the base part made of a transversely stiff but
 longitudinally flexible material, such as spring steel, carbon fibers,
 glass fibers or kevlar fibers, titanium or the like, ensures an
 anatomically correct sitting with a hollow and therefore less stressed
 sacrococcygeal region and an axially stressed ischial tuberosity region,
 and simultaneously a base structure for the cushion adapting to the body
 is provided which, although it has a certain stiffness, can be
 continuously changed and adapted to the momentary sitting wishes; thus,
 for example, when a tired sitting person who is slumped forward slides to
 the front. The transversely stiff and longitudinally flexible base part
 will then adjust itself such that the ischial tuberosities axially load
 the base part. The cushion, which corresponds to the anatomical
 requirements and cushions the pressure isobars of the body during the
 sitting in different positions, is pulled onto this hard transversely
 stable but longitudinally flexible base structure. The longitudinally
 flexible but stiff base part can be placed into the cushion, can be
 suspended on the subframe, can be adjusted and/or can be sprung as a
 whole. By means of additional mechanisms, which are mounted on the
 suspension of the base part on the subframe, the arching can be adjusted
 in the area of the longitudinal flexibility and can be adapted to the
 momentarily desired sitting position. The cushion may consist of foam, of
 rubberized hair, of a breathing material, of a perforated silicone cover,
 of air chambers or the like. On the whole, the sitting and/or lying
 arrangement combines the positive characteristics of the anatomic seat
 design with the positive elements of the individual readjustability, in
 which case as little material as possible and as much material as
 necessary is used.
 Other objects, advantages and novel features of the present invention will
 become apparent from the following detailed description of the invention
 when considered in conjunction with the accompanying drawings.

DETAILED DESCRIPTION OF THE DRAWINGS
 In the drawings, similar reference numbers with respective different letter
 suffices "A, B - - - " are used to designate generally similar functioning
 structures in the respective different embodiments illustrated. Unless
 otherwise indicated in the following description, the description of the
 structures with similar reference numbers, but with no or different letter
 suffices, should be referred to.
 The two seat parts of a vehicle seat, which are schematically shown in
 FIGS. 1 and 2 as longitudinal sectional views as an example of a general
 sitting and/or lying arrangement. The sitting and/or lying arrangements
 contemplated by the invention include an airplane seat having a backrest
 which can be tilted toward the rear for the purpose of relaxation, an
 orthopaedic seat or an orthopaedic lounger, a wheelchair and the like,
 each having a stable subframe 10, 10A and a flexible support 11, 11A which
 is composed of a base part 12, 12A and a cushion 13, 13A. The base part
 12A has a transversely stiff and longitudinally flexible construction and
 is formed in the embodiments shown of a thin corrugated spring plate 14,
 14A whose wave height and material thickness depend on the material
 selection and load. The term "spring plate" is used in the following as a
 synonym for a thin flexible plate or foil and does not characterize the
 material of the thin plate or foil. Spring steel, carbon fibers, glass
 fibers or kevlar fibers or titanium can be used as the material for the
 corrugated spring plate.
 FIG. 3 is a perspective cutout of the base part 12, 12A constructed as a
 corrugated spring plate 14, 14A. In this case, the profile of the
 corrugation has a sinusoidal construction.
 FIGS. 5, 6 and 7 show additional examples of the wave profile of the
 corrugated spring plate 14, 14B, 14C, 14D. In FIG. 5, the wave profile of
 the plate 14B has a rectangular shape; in FIG. 6 the wave profile of the
 plate 14C is triangular with rounded vertexes; and in FIG. 7, a second
 corrugation with a significantly smaller corrugation period is
 superimposed on the triangular wave profile of the plate 14D. As
 illustrated in FIG. 5, air-filled hoses 15 can also be placed in the wave
 troughs 141 of the corrugated spring plate 14, as viewed from the
 direction of the cushion 13, 13A.
 In the embodiment of FIG. 1, the corrugated spring plate 14 is embedded
 within the cushion 13 and the cushion 13 is connected with the subframe
 10. In this case, the cushion 13 is preferably constructed as a core made
 of a foamed material which encloses the corrugated spring plate 14, the
 corrugated spring plate being perforated in order to permit the
 foaming-in.
 In the embodiment of FIG. 2, the corrugated spring plate 14A is suspended
 at its end edges 143, 144, which extend transversely to the corrugation,
 on the subframe 10A, and the cushion 13 rests directly on the corrugated
 spring plate 14A. In addition--as illustrated only in FIGS. 13 and 4D--the
 corrugated spring plate 14, 14A may be fastened at its longitudinal edges
 145 extending in parallel to the corrugation by means of spring-elastic
 elements, preferably tension springs 16, on a subframe 10, 10A, or on cap
 31 in the FIG. 13 embodiment as further described below.
 FIGS. 4A, 4B, 4C and 4D schematically show the displacement of the base
 part 12, 12A in the seat part according to FIG. 4A or 4B when a sitting
 person 17 loads the seat in two different sitting positions. In both
 sitting positions, the stressing of the ischial tuberosities 171 is
 orthopedically correct (not the sitting position). The pressure acts from
 below axially upon the ischial tuberosities 171 of the sitting person 17,
 and the hollow placement of the sacrococcygeal region 173 is ensured.
 FIGS. 4C and 4D also schematically show the displacement of the base part
 12, 12A in the seat part when the seat is loaded by a sitting person 17.
 In FIG. 4D, the pressure is applied from below vertically onto the ischial
 tuberosities 171 of the sitting person 17. In contrast, in the case of the
 seat part of a conventional vehicle seat outlined in FIG. 4C, the base
 plate 12P arches through more in the center because it is not transversely
 stiff as in the case of the seat according to 4D, and the pressure is not
 applied vertically but diagonally from below to the ischial tuberosities
 171. The sitting person 17 feels closed in and notices pressure loads on
 the lateral pelvis. In the case of the seat 4D with the pulled-in
 corrugated spring plate 14, 14A as the result of the transverse stiffening
 of the corrugations, a hanging-through in the center is prevented and, by
 means of its longitudinal flexibility, a cushioning is guarantied and an
 adaption to the sitting position is ensured. Which of the wave profiles
 illustrated in FIGS. 3 and 5 to 7 is used in the case of the corrugated
 spring plate 14, 14A, 14B, 14C, 14D depends on the cushioning
 characteristic of the material and the stress to which the seat is
 subjected. The inserted, air-filled hoses 15 shown in FIG. 5 take over,
 for example, a massaging function.
 In FIG. 4A, the sitting person is sitting upright and attentive. He is
 supported by means of the ischial tuberosities 171. The spinal column 172
 is supported on the backrest 21. In FIG. 4B, the sitting person is tired,
 slumping and slides toward the front. In the case of a standard seat, this
 would result in pressure on the sacrococcygeal region which is
 uncomfortable and results in complaints and uneasiness. In contrast, in
 the case of the new type of seat introduced here, the base part
 automatically adjusts itself such that the ischial tuberosities are again
 axially loaded.
 FIGS. 8A and 8B are schematic longitudinal sectional views of a vehicle
 seat with a seat part 20 and a backrest. The subframe 10E consists of a
 seat frame 22 of the seat part 20 and of a backrest frame 23 of the
 backrest 21 which are rigidly connected with one another. As an
 alternative, the backrest frame can also be swivellably fixed on the seat
 frame in order to be able to be changed into a lying arrangement used for
 relaxation. The whole subframe 10E can be tilted about a tilting axis 24
 extending transversely to the sitting direction and can be swivelled from
 a so-called driving position (FIG. 8A) into a resting position (FIG. 8b)
 used for relaxation. By means of its forward end edge 143 extending
 transversely to the corrugation, the corrugated spring plate 14E is
 suspended on a forward cross strut 221 of the seat frame 22 and, by means
 of its rearward end edge 144 extending transversely to the corrugation, it
 is suspended by means of spring elements 25 on an upper transverse spar
 231 of the backrest frame 23. In the embodiment of FIGS. 8A and 8B, the
 spring elements 25 can also be eliminated and the corrugated spring plate
 14E can be fixed by means of its end edge 144 directly on the upper
 transverse spar 231, as in the embodiments of FIGS. 10 and 11. The cushion
 13E covers the corrugated spring plate 14E in one piece and, by means of
 its forward section, forms the seat cushion 131 and by means of its
 rearward section, forms the backrest cushion 132. When the vehicle seat is
 swivelled into the resting position, the pelvis is displaced toward the
 front by the amount "a" in FIG. 8B. The corrugated spring plate 14E goes
 along with the changed sitting position so that the sitting person sits
 again in an orthopedically correct manner. The change of the position of
 the corrugated spring plate 14E and of the cushion 13E is illustrated in
 FIG. 8B, the contour shown by a broken line illustrating the course of the
 cushion surface when the seat is in the driving position according to FIG.
 8A.
 In another embodiment of a vehicle seat with a seat part and a backrest,
 which is outlined in a longitudinal sectional view in FIG. 9, the subframe
 10F is again composed in one piece of the seat frame 22F and the backrest
 frame 23F, and the corrugated spring plate 14F is fixed by means of its
 end edges 143, 144 by way of spring elements 25F on the forward cross
 strut 221 of the seat frame 22F and on the upper transverse spar 231 of
 the backrest frame 23F. The cushion 13F with its sections forming the seat
 cushion 131 and the backrest cushion 132 rests directly on the corrugated
 spring plate 14F. For adjusting the depth of the seat, an adjusting
 arrangement 26 is assigned to the corrugated spring plate 14F by means of
 which adjusting arrangement 26 the corrugated spring plate 14F is
 longitudinally displaceable, that is, displaceable in the direction of the
 corrugation. The adjusting arrangement 26 has a driving roller 27 which is
 arranged on the or close to the forward cross strut 221 of the seat frame
 22F and extends transversely over the corrugated spring plate 14F, which
 driving roller 27 engages by means of a cam profile adapted to the wave
 profile in the corrugated spring plate 14F. The corrugated spring plate
 14F is guided around the driving roller 27 so that a sufficient section of
 the corrugated spring plate 14F engages with the cam profile of the
 driving roller 27. When the driving roller 17 is rotated into one or the
 other rotating direction, the corrugated spring plate 14F is displaced
 into one or the other direction while stretching one or the other spring
 element 25F and the depth of the seat is thereby shorted or lengthened.
 In the case of the vehicle seats schematically illustrated in longitudinal
 sectional views of FIGS. 10 and 11 which have a seat part and a backrest,
 a massaging device is provided instead of a seat depth adjusting device.
 As not illustrated here in detail, the corrugated spring plate 14G is
 suspended by means of its transversely extending end edges again on the
 forward cross strut of the seat frame 22G and on the upper transverse spar
 of the backrest frame 23G and is covered by the cushion. In FIG. 10, air
 hoses 28 are placed in the, viewed from the direction of the cushion 13G,
 wave troughs 141 of the corrugated spring plate 14G, which air hoses 28
 are connected to a compressed-air device 40 for the selective individual
 adjusting of their air pressure. The variation of the air pressure permits
 a pressure point change and thus a massaging effect and influences the
 hardness of the seat.
 The massaging effect in the embodiment of FIG. 11 is achieved by means of a
 plurality of eccentric rollers 29 which are rotatably arranged on the seat
 frame 22H and on the backrest frame 23H. In this case, each eccentric
 roller 29 is placed against a wave crest 142 of the corrugated spring
 plate 14. The individual eccentric rollers 29 are driven by means of a
 toothed belt not shown here. During the rotation of the eccentric rollers
 29, these press upon the corrugated spring plate 14H and thereby increase
 or reduce the pressure point.
 FIGS. 12 and 13 schematically illustrate the backrest of another embodiment
 of a vehicle seat as a longitudinal sectional view (FIG. 12) and as a
 cross-sectional cutout (FIG. 13). A plurality of adjusting members 30 is
 arranged on the backrest frame 23I which are constructed to be
 displaceable in the sitting direction, thus in the direction of the seat
 depth, and are applied to the corrugated spring plate 14I. A cap 31 is
 firmly connected with each free end of an adjusting member 30, on which
 cap 31 a tension spring 16 is fixed which is suspended by means of its
 other end on the longitudinal edge 145 of the corrugated spring plate 14I.
 The corrugated spring plate 14I is therefore fastened along its two
 longitudinal edges 145 in the area of the backrest frame 23I by way of a
 plurality of tension springs 16 to a corresponding number of adjusting
 members 30. The adjusting members 30 may be pneumatically, electrically,
 hydraulically or mechanically driven, and thereby more or less advance
 from the backrest frame 23I. By means of their adjustment, an adjustment
 of the back support is possible, as indicated in FIG. 12 by the contour of
 the corrugated spring plate 14I illustrated by a dash-dotted line. The
 individual caps 31 on the adjusting members 30 can also be connected with
 one another in one piece and will then form a flexible adjusting frame
 which is displaceably fixed on the backrest frame 23 by way of the
 adjusting members 30.
 In the case of the seat schematically illustrated as a longitudinal
 sectional view in FIG. 14, the transversely stiff and longitudinally
 flexible base part 12J and the cushion 13J for the seat part and the
 backrest are constructed separately from one another, the corrugated
 spring part 14J in each case being separately fixed, as described, on the
 seat frame 22J and on the backrest frame 23J. The spring elements not
 shown here and the possible adjusting arrangement are to be provided in
 each case for the seat part and the backrest. The backrest frame 23J is
 swivellably held on the seat frame 22J and can be locked in any swivelling
 position so that the seat can also be used as a lying arrangement. In
 addition, the seat part and the backrest can be conceived such that the
 two base parts 12J with the seat cushion 131 and the backrest cushion 132
 can easily be detached from the seat frame 22J and the backrest frame 23J
 and can be removed.
 The invention is not limited to the above-described embodiment of a vehicle
 seat. In the case of a corresponding angle of slope between the seat part
 and the backrest, embodiments used for use as a lounger are also
 contemplated.
 In addition to the above-described applications, the possibility of a
 design for a wheelchair should also be stressed. Such a wheelchair can
 then be held in a more stable manner; the patient can sit in it more
 firmly and securely, and orthopaedic correction pads can be used better
 and more safely and durably. By means of the adjusting mechanisms
 according to the invention, different sitting and lying positions can be
 adjusted. If the base part with the cushion is constructed to be removable
 from the frame, the wheelchair can also be constructed to be foldable.
 The foregoing disclosure has been set forth merely to illustrate the
 invention and is not intended to be limiting. Since modifications of the
 disclosed embodiments incorporating the spirit and substance of the
 invention may occur to persons skilled in the art, the invention should be
 construed to include everything within the scope of the appended claims
 and equivalents thereof.