SEAT FOR CHAIR

Abstract: The chair seat consists of a seat cushion (2) with a central part (3) having through-going ventilating holes (4) and a rearwardly extending part (7). The seat is covered by a cover (5). The central drop-shaped part (3, 7) is made of a softer material than that of the seat cushion (2) itself. The result is that the load on the seat and pelvic region of the user is distributed in such a manner that the central part of the seat is relieved in relation to the load on the thighs and buttocks. At the same time the central and softer part (3) is designed in such a manner that the coccyx rests thereon thus avoiding adverse loads on the spine.

Description: SEAT FOR CHAIR The invention relates to a seat for a chair as indicated in the introduction to claim 1. The invention is preferably intended for chairs of the kind which are used many hours each day such as working chairs, office chairs- motor vehicle seats etc, special chairs for various groups of patients suffering from various pains in the pelvic region but may of course also be used for rest chairs of various types. The seat is particularly suitable for improving ergonomics in connection with office and working chairs. There are known many different designs of office and working chairs where efforts have been made to design the seat, the seat suspension and the positionings thereof in such a manner that the back is loaded in a natural manner so that injuries are avoided. Long-term effects of various kinds may, however, be found by any chair and there are particularly many problems with the chair seat. It is the object of the invention to improve the padding of a chair seat in such a manner that many of the known long-term troubles are completely avoided. This object is achieved by designing the seat according to the invention as disclosed in the characterising part of claim 1. The load on seat and pelvic region of the user is simply distributed so that the central part is relieved in relation to the load on the thighs and the buttucks. There is thus made allowance for the human physiognomy in that the parts of the body which are adapted to take loads will take over some of the load from other parts. If the seat according to the invention is designed as disclosed in the characterising part of claim 2 , there is moreover obtained a relief of the lower part of the back in that the coccyx will rest on the softer material. There is thus obtained a further improvement of the properties of the seat since the spine is not adversely loaded - the muscles are rather allowed to work dynamically so that the segments in the entire spine will work within their natural area of motion. The mere use of a fixed seat according to the invention thus offers the same advantages as are otherwise only obtained by the known chairs where the seat can be tilted forward. If the seat according to the invention is used on a tilting chair, all the advantages of the tilting seat are increased because the pressure distribution on the body becomes absolutely ideal. The seat according to the invention is preferably designed as disclosed in the characterising part of claim 3 in that the central soft area may thus be freely ventilated. Furthermore the seat according to the invention is designed as disclosed in the characterising part of claim 4. There is thus obtained optimum ventilation without reducing the advantages mentioned in claims 1 and 2. The result is' therefore an ideal combination in that the central part is ventilated optimally so that the user will not have the natural microclimate in the seat region ruined by too great secretion of sweat when for example sitting on an office chair all day. The chair has moreover proved to be very comfortable and relieving to sit on if the user is for example suffering from menstrual pains or has descended pelvis or other sufferings or diseases. The seat according to the invention is preferably designed as disclosed in the characterising part of claim 5. It is thus possible in a simple manner to achieve the desired effects and there is obtained a seat which is very simple to produce. The seat according to the invention is preferably designed as further defined in the characterising part of claim 6. This material is compressed by the body weight to a suitable hardness in that it ,has turned out that precisely the data for the materials given in the claim will produce the optimum effects. The seat cushion itself surrounding the soft centre area will get harder by compression and feel firm to sit on before the softer centre area achieves this effect so that the load will primarily be taken up by the hardest part of the seat cushion. Finally, the seat according to the invention is preferably designed as disclosed in the characterising part of claim 7. The drop-shaped design extending from the rear edge of the seat towards its centre where the soft part is of • almost circular shape has turned out to give the desired properties and advantages, and the size of the central soft area as disclosed in the claim has turned out to suit the majority of the users. The invention will be further explained in the following with reference to the drawing showing a preferred embodiment of the invention wherein Fig. 1 shows a plane section of a seat in the direction I-I in Fig. 2, and Fig. 2 shows a vertical section on a larger scale of the seat in Fig. 1 in the direction II-II. The seat 1 consists of a seat bottom 6 which is for example manufactured of formed plywood or another suitable material. On the seat bottom 6 there is arranged and secured a cushion 2 with a central part 3 having a rearwardly extenting part 7. The seat cushion or the padding is covered by a cover 5 of fabric or another non-airtight material. Centrally in the seat cushion 2 there is arranged a drop-shaped central part 3 with ventilating holes or channels 4 extending all the way through the central part and out through the seat bottom 6. The central area 3 extends all the way to the rear edge of the chair seat so that there is formed a channel-like area 7. The soft central part 3 can therefore be ventilated through the rearwardly extending area 7 as well as through the ventilating holes 4 . The seat cushion 2 is for example made of polyurethane foam with a density of 48.0 kg/m 3 and a hardness index of 200N (N:newton). The drop-shaped area forming the central soft part 3 and 7 is for example made of polyurethane foam with a density of 36.0 kg/m 3 and with a hardness index of 150N. The density of the materials are measured according to ISO 1855 and the hardness according to ISO 2439, procedure A by 40% compression. Both materials are fire retarded so that they comply with the rules in California Bulletin No. 117, sec. A+D. The seat structure according to the invention may be used for almost any kind of chair in that the soft area 3 is designed in drop-shape as shown in the drawing and with a width T of the central part of about 10-20 cm, preferably about 15 cm. It is obvious to a person skilled in the art that the physical sizes as well as the relative sizes of the areas 2 and 3 may be changed and adapted to each other both with a view to which chair the seat is to be used for and with a view to the person who is to use the chair. It is for example possible to imagine that chair seats in the same size are designed with different sizes of the drop-shaped area.

Claims: PATENT CLAIMS 1. Seat (1) for a chair comprising a fixed seat bottom (6) and a resilient cushion with a cover (5) supported thereon, c h a r a c t e r i s e d in that the resilient cushion (2) is designed with a central area (3) which is made of a softer material than that of the cushion. 2. Seat according to claim 1, c h a r a c t e r i s e d in that the central area has a rearwardly extending part (7) made of the same material as the central area (3) and formed integrally therewith. 3. Seat according to ' claim 2, ch a r a c t e r i s e d in that the rearwardly extending part (7) extends all the way to the rear edge of the seat. 4. Seat according to any one of claims 1-3, c h a r a c t e r i s e d in that the central area (3) is designed with through-going ventilating holes (4) extending all the way through the seat and substantially perpendicularly to the plane of the seat. 5. Seat according to any one of claims 1-4, c h a r a c t e r i s e d in that the resilient cushion (2,3) is made of foam rubber, the two areas being made of foam rubber having different hardness and density. 6. Seat according to claim 5, c h a r a c t e r i s e d in that the foam rubber is polyurethane and that the central part (3) has a density of 34-38 kg/m 3 , preferably 36 kg/m 3 and a hardness index of about 15ON, and that the seat part (2) has a density of 44-52 kg/m 3 , preferably 48 kg/m 3 and a hardness index of about 20ON. 7. Seat according to any one of claims 1-6, c h a r a c t e r i s e d in that the central part (3) is. substantially drop-shaped and has a transverse measurement (T) at its broadest place of 10-20 cm, preferably about 15 cm.

Inventors: HOUMANN-POULSEN PER, HOUMANN-POULSEN, PER
Applicants: HOUMANN POULSEN PER, HOUMANN-POULSEN, PER
Application year: 1986
Main classification: A47C7
IPC codes: A47C7