VENTILATED BODY SUPPORT

Abstract: A body-supporting device forming the seat (1) and/­ or the backrest (15) of a chair and adapted to avoid sweat­ ing caused by the thermal insulation of the chair is charac­ terized by the fact that at least those sections (2) of the exterior surface of the device that form the support sur­ faces for parts of the body of a person sitting in the chair are made of air-permeable material. At least one opening (11) to the exterior is arranged in said device to communi­ cate with the interior side of said air-permeable sections (2). A suction device capable of producing a negative air pressure, such as a suction turbine, may be connected to said opening. The interior of the body-supporting device is so arranged that, when a suction device is thus connected and is running, air that is exterior to said support surfaces will be drawn through the air-permeable sections (2) and via the interior of the body-supporting device and out of it through said opening (11), in order to remove heat radiated by the body of the person, in particular from the region be­ tween said parts of the body and the air-permeable sec­ tions, and to cool the latter by means of the airstreams thus created.

Description: This invention applies to a body-supporting device forming the seat and/or back rest of a chair, its purpose being to avoid sweating caused by the thermal insulation of the chair. The term "chair" is used to cover all types of furniture intended for sitting thererin, such as vehicle seats in all kinds of vehicles, office chairs and domestic arm chairs. This should be born in mind, as the invention is described below as it would be applied to the driver's seat of a conventional vehicle. Every driver who has driven a car in hot weather, for example during the summer holiday period, has certainly experienced great problems with the sweating that takes place from those parts of the body that bear upon the driver's seat. This is because the chair, upon the body surfaces in contact with the chair, acts as thermal insulator substantially obstructing and reducing the capability of the body to emit heat by radiation. The consequence is that other parts of the body must contribute more to meet the requirements of the body to be cooled by heat radiation. To achieve this it is common to open one or more windows, which results in draughts and negative consequences for health and and has a very small positive influence. However, if the temperature in the car is high enough, the body cannot lose enough heat by radiation without sweating. In this case the sweating will be particularly noticeable where the body is in contact with the chair, as an effective barrier to vapour diffusion is formed between the body and the support surfaces of the chair, making evaporation more difficult and causing these parts of the chair to become wet with sweat, which sticks to shirts, trousers and other items of clothing and causes severe discomfort. This phenomenon occurs even if the seat covers are made of material that can "breathe", avoiding non-permeable material such as leather. Known devices of this kind have the object to avoid sweating of a person sitting in a chair by any type of air streams generated. It is desired that devices of this type create a uniform distribution of air streams from the support portions onto which the person is sitting and into the seat and backrest, respectively. Such a uniform distribution of the air streams may be achieved by arranging many small air-conducting tubes inside the seat and the backrest, respectively, and provide these channels with holes letting air pass therethrough according to a desired pattern, as described in FR-A-94 417. This technique to achieve a uniform distribution of the negative pressure over the inner side of the air-permeable sections forming support surfaces has been utilized by the device according to FR-A-94 417. As a consequence thereof, it is desired to avoid the arrangement of air channels or tubes in the chair, and attempts have been made to arrange a suction-equalizing arrangement in the interior of the device in other ways. An example thereof is shown in US-A-3 137 523. This device comprises a porous body arranged between a cavity located inside the chair, into which a duct to a fan emerges, and the sections of the chair forming support surfaces. This filling material distributes the air streams to different holes arranged in the sections forming support surfaces. US-A-3 736 022 describes a moulded seat of a non-porous material, in which a recess for receiving an insert is arranged. The insert is made of porous material and connected to a fan through vent holes. This device does not either provide any uniform distribution of the negative pressure created by the fan over the support surfaces against which parts of the body of the person are intended to bear. BRIEF DESCRIPTION OF THE INVENTION The object of the present invention is to construct a device of the type discussed above, which has a suction-equalizing arrangement generating a very uniform distribution of the negative pressure created by the suction device on the inner side of the air-permeable sections over the surfaces against which body parts of a person sitting in the chair are intended to bear, and this shall be obtained while removing the disadvantages connected to air channels or tubes inside the seat and the backrest, respectively. According to the invention this object is obtained by providing the suction-equalizing arrangement of the body-supporting device with the features defined in the characterizing part of the new claim 1. By the arrangement of the airtight elastic bag tightly bearing under tension against the first layer of fibrous material and the porous body, as well as the arrangement of the holes in the bag according to said pattern and the mutual arrangement of the holes and the opening for connection to the suction device, a very uniform distribution of the negative pressure created by the suction device over the support surfaces against which the body parts of the person in question bear will take place. Owing to the fact that the bag tightly bears under tension against the lateral walls of the porous body the pores in the surface region of this body will be closed and all the air from the fibrous layer will be forced to pass through the porous body so as to reach the opening. This leads to a very even distribution of the air pressure at the upper surface of the porous body. This distribution of air pressure becomes even more uniform thanks to the arrangement of the fibrous layer, said layer also being absolutely necessary so as to prevent the portions of the perforated bag exerted to loads from bearing directly against the upper side of the porous body, which would result in an obstruction of the pores close to the surface and an uneven distribution of the negative air pressure. Furthermore, by the arrangement of the holes the airtight bag enables a distribution of the negative air pressure over the surfaces desired being just as efficient as would be possible by arranging air tubes. Accordingly, the device according to the invention obtains a very uniform distribution of the negative air pressure under the support surfaces against which body parts of a person rest, and this is achieved without the disadvantages attached to the devices having air channels or tubes. Another advantage of the suction-equalizing arrangement according to the invention is that it may easily be manufactured while generating low costs, since for instance the section located outside the bag on the level of the porous body has not to be airtight. Other advantageous features of the invention and the advantages thereof will be made apparent in the following description of a preferred embodiment of the invention, and in the dependent claims, one being that several features have the purpose of achieving as effective and as localised a suction effect as possible, thus utilising minimum effect in the suction device. BRIEF DESCRIPTION OF THE DRAWINGS With reference to the appended drawings, below follows a description of a preferred embodiment of the device according to the invention cited as an example. In the drawings: fig 1 is a sectional view of a preferred embodiment of the invention as applied to the seat of the driver's seat of a vehicle, in which the central portion of the seat has been removed for clarity, fig 2 is a perspective view of a seat constructed according to the invention, in which external parts have been removed to illustrate some of the details of the interior of the device important for the function of the device according to the invention, and fig 3 is a perspective view of a driver's seat contructed according to the invention, compressed by the weight of a person seated on it, in which a section has been taken across the seat. DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION The following is a description of a body-supporting device which forms both seat and backrest of a chair, but it is quite possible that only the seat or only the backrest of a chair would be provided with such a device, if this were desirable. In the present case the chair is identical with the body-supporting device, and the shorter term may be used for the latter. Fig 1 shows how the seat 1 of a chair is constructed according to the invention, the backrest being constructed in a corresponding way. The sections 2 which form supporting surfaces for parts of the body of a person sitting in the chair are made of an air-permeable material, preferably and in this example of wool. At the sides and the front of the seat, the woollen layer 2 is sewn onto an airtight layer 3, such as plastic or leather, which covers the sides and underside of the seat. The interior of the seat will now be described and to better illustrate how the seat is constructed, the component parts shown in fig 2 are not depicted in their correct relative scale, and for gaining further clearness layers which in reality are superposed in close contact with each other have been spaced apart. Immediately beneath the woollen layer 2 is a layer 4 with conducting circuits for electrical heating of the seat cushion. Beneath the electrical heating layer 4 is a second woollen layer 5, similar to the first one. The woollen layers are preferably about 5 mm thick. The second woollen layer 5 is tightly connected to the airtight layer 3, so that all air penetrating through the outer woollen layer must pass through the second woollen layer 5 in order to reach the interior of the seat. Beneath the second woollen layer 5 is a bag 6 of virtually airtight material. The bag, in this example, is made of an elastic sheet rubber material, perforated in the direction of the second woollen layer by a number of holes 7 with a diameter of preferably about 20 mm. The elastic sheet rubber material tightly encloses and is in close contact with elements arranged in the bag. Immediately inside that side of the sheet rubber material 6 that is directed towards the support surfaces of the seat is a first layer 8 of fibrous material,here a disc of horsehair. Beneath the horsehair layer 8 is arranged a porous body 9 of foamed plastic. The thickness of the foamed plastic body is about 100 mm when not compressed. Beneath the foamed plastic body 9 is placed a second horsehair layer 10. The bag 6 has an opening 11 close to the second horsehair layer 10 and towards the side of the seat, to which is attached a preferably flexible tube 12 which protrudes from the seat and is connected to the negative pressure side of a suction turbine 13 (see fig 2). The function of the device described above will now be explained. When the suction turbine 13 is powered up it creates a negative pressure at the opening 11 in the perforated sheet rubber material 6. The sheet rubber material is tightly bearing under tension against the sides of the foamed plastic body, whereby the pores close to those surfaces of the foamed plastic body are sealed, so that no air can arrive to the opening 11 without passing through the foamed plastic body 9. Both horsehair layers 8, 10 are permeable to air, as is the porous foamed plastic body 9 itself, and they have a tendency to distribute a concentrated negative air pressure uniformly over a larger area. This fact and the action of the suction turbine create a negative air pressure substantially evenly distributed over the upper side of the porous body, as indicated by the small arrows 14. This evenly distributed negative air pressure provides substantially the same suction effect at each of the holes 7 in the perforated sheet rubber material 6. Reference is now made also to fig 2. The holes 7 in the sheet rubber material are arranged in a pattern which substantially corresponds to the shape of the projection on the seat and the backrest of those parts of the body that would normally bear thereupon. Thus the holes in the seat, seen from above, are arranged in the form of a letter U, corresponding to the extension of the thighs and buttocks of a person sitting in the chair. The sheet rubber material arranged for the backrest is perforated along a line substantially corresponding to the spinal column of the person. The suction-equalising device formed by the perforated sheet rubber material and its contents causes substantially equal amounts of air to be drawn through the woollen layers 2 and 5 in the vicinity of each of the holes. Woollen layer 2 will spread the suction effect somewhat, so that it is applied to a larger area of the support surfaces of the seat than would correspond to a direct projection of the corresponding holes 7. The effect of this is that a coherent area corresponding to the support surfaces against which a person's thighs and buttocks bear will have air drawn through it. By this means, those parts of the body in contact with the seat will be cooled by the passage of the air and kept dry. A very good and appropriately large transport of heat from these contact surfaces of the body can thereby take place. The suction-equalising arrangement not only produce air streams evenly distributed over the relevant surfaces, but also ensures by means of the disposal of the holes 7 that the suction effect is limited to these contact surfaces. Through the latter fact suction is avoided where it is completely superfluous, which makes possible a great economy of power, so that the suction turbine can run at a rate as low as possible and be made as silent as possible. Ideally, the noise made by the suction turbine should not be audible by a person sitting in the chair. This aim is more easily achieved if a suction turbine is mounted in the baggage space of the vehicle, but also other locations, such as in the engine compartment, are possible, if there is space. It should be noted, however, that the "noise" of the suction turbin is at such a low level that it could also be mounted in the same air space, close to the chair. Preferably, it should be possible to regulate the speed of rotation of the suction turbine, so that it can be adjusted according to the conditions, of temperature, clothing, etc. Fig 2 shows how the backrest 15 and seat 1 of a chair according to the invention each are composed by a suction-equalising device, and each device has an opening, through a branching connected to the same tube 12 leading to a suction turbine 13. It would also be, possible, though hardly to be recommended, to construct backrest and seat as one piece, using the same perforated, bag forming sheet rubber material in the construction of the backrest as well as the seat. Fig 3 shows how the seat 1 will be compressed by the weight of the person sitting on it. It is clearly shown how the foamed plastic body 9 is thereby deformed and also has a shock-absorbing and comfort-enhancing funtion. The first horsehair layer 8 prevents those parts of the perforated sheet rubber material that are under compressive load from making direct contact with the upper side of the foamed plastic body, which would otherwise seal the surface pores and cause an uneven distribution of negative air pressure. The presence of the first fibrous layer 8 is therefore necessary, while it would be possible, though not recommended, to omit the second fibrous layer 10. The elastic sheet rubber material bag is a very important feature of the present invention. It eliminates the need for air channels or tubes inside the chair. This is a great advantage, as air channels can easily be closed by the loads exerted thereon by a person sitting in the chair, and air tubes seriously decrease the sitting comfort, so that it will be uncomfortable to sit in the chair for any length of time. The device according to the invention is most useful at ambient temperatures between 18 and 38°C. The invention is not in any way limited to the preferred embodiment described above, but a man skilled in the art should without difficulty be able to find out a number of possible modifications, whithout thereby departing from the basic idea of the invention. It would be possible, for example, to replace the suction turbine by any other suitable suction device. The electrical heating layer could be omitted if this was desirable, in which place only one woollen layer would be necessary. Although it has been found very advantageous to use wool as the air-permeable material for the support surfaces in question, it will be feasible to use any other material with similar properties. The virtually airtight material enclosing the sides, underside and back of the chair could be omitted and replaced by an air-permeable layer, although it would then be advisable to retain a layer of such a virtually airtight material around the air-permeable portions at least in the region of said support surfaces in order to avoid suction of air from portions against which parts of the body of a person do not bear. The foamed plastic and the horsehair of the porous body and the fibrous layer, respectively, could be replaced by any other material with similar properties. The opening for the tube to the suction device could be located close to the woollen layer if this was desirable, but it would then be necessary to arrange some kind of airtight duct inside the bag emerging close to the underside of the foam plastic body and there creating a negative air pressure. It would also be possible to locate said opening directly under the seat and the rearside of the backrest, respectively, or give it any other suitable location. Although a U-shape and a line, respectively, are preferred for the patterns formed by the holes in the perforated member, other patterns would also be feasible, although they would not be nearly as effective.

Claims: A body-supporting device forming the seat (1) and/or the backrest (15) of a chair and arranged to avoid sweating caused by the thermal insulating capacity of the chair, at least those sections (2) of the exterior surface of the device that form support surfaces for parts of the body of a person sitting in the chair being made of a material that is easily permeated by air, at least one opening (11) to the exterior being arranged in said device to communicate with the interior side of said air-permeable sections (2), said suction device (13) that is capable of creating a negative air pressure, such as a suction turbine, being connectable to said opening, the interior of the body-supporting device being arranged to allow a suction device, when connected and running, to draw air that is exterior to said support surfaces through the air-permeable sections (2), via the interior of the body-supporting device and out of it through said opening (11), the interior of said body-supporting device having a suction-equalizing arrangement (6-10) arranged to create a substantially even distribution of the negative air pressure generated by the suction device (13) over the inner side of the air-permeable section (2) forming support surfaces, characterized in that the suction-equalizing arrangement comprises a perforated bag (6) of substantially air tight and elastic material and elements (8, 9) arranged therein, said bag enclosing said elements while tightly bearing under tension thereagainst and being through an opening sealingly connected to said opening (11) for connection to the suction device (13), that the bag (6) has holes (7) located close to the sections forming support surfaces, that the holes (7) are arranged so as to together form a pattern that substantially corresponds to the shape of the projection onto the seat (1) and/or backrest (15) of those parts of the body intended to bear thereupon, that inside the bag (6) there is arranged a porous, air stream diverging body (9), such as a body of foamed plastic, said bag (6) bearing tightly against the lateral walls of said body (9) and closing the outer pores of said lateral walls, that the porous body has a first large surface facing said holes (7), that the bag has said opening (11) for connection to the suction device (13) at a second large surface of the porous body turned in the opposite direction to the first surface, so that the air drawn through the holes (7) of the bag must pass through the porous body (9) in order to reach said opening (11), and that a first layer (8) of fibrous material, preferably horse hair, is located between the perforated bag (6) and said first surface of the porous body (9), so that bearing of the perforated bag (6) against this surface and thereby sealing of the surface pores of the porous body is avoided and the air drawn towards said opening must pass through the layer (8) of fibrous material. A device according to claim 1, characterized in that at least the exterior surfaces of the body-supporting device adjacent to said support surfaces are made of substantially airtight material, so that virtually all air to be drawn to said opening (11) will pass the sections forming support surfaces. A device according to claim 1 or 2, characterized in that a second layer (10) of fibrous material is located onto said second large surface of the porous body (9). A device according to any of the preceding claims, characterized in that the air-permeable material (2) is wool. A device according to claim 3, and forming both seat (1) and backrest (15) of a chair, characterized in that both seat and backrest contain, interior to the air-permeable sections (2), a perforated bag (6) containing an assembly of fibrous layers (8, 10) and a foamed plastic body (9), each bag having an opening (11) for connection to a suction device (13), and that the openings are located respectively at the lower part of the backrest and at the rear of the seat on the same side of the chair so as to enable simple connection of both elastic bags (6) to the same suction device (13). A device according to any of the preceding claims, characterized in that the perforated bag (6) is made of an elastic sheet rubber material.

Inventors: TENNSTEDT, CHRISTER, WYON, DAVID
Applicants: TENNSTEDT, CHRISTER, WYON, DAVID
Application year: 1988
Main classification: A47C7
IPC codes: A47C7