Abstract:
An expandable chamber support system for vehicle seat and mattress applications includes an expandable chamber constructed from facing sheets of flexible impermeable material that are sealed along their marginal edges. One of the sheets is formed of electrically conductive an elastomeric membrane that is electrically resistance heated while providing a source of pressure support for an occupant supported by the expandable chamber.

Description:
This application is a divisional application of Ser. No. 09/640,445, filed on Aug. 17, 2000. 
    
    
     TECHNICAL FIELD 
     This invention relates generally to inflatable air cell systems for occupant support in seating and mattress applications and, more particularly, to the provision of an expandable chamber that includes a wall segment formed of conductive material dispersed in polymeric material and operable to heat seating or mattress applications. 
     BACKGROUND OF THE INVENTION 
     Fluid expandable chambers such as expandable chamber or air cells, particularly for pneumatically adjustable occupant support systems in seating or other support applications, are frequently constructed from facing layers of a flexible, air-impermeable material such as thermoplastic urethane, fabric reinforced polyvinylchloride, and other plastic film materials, that are dielectrically sealed or otherwise joined about their marginal edges to enclose an interior inflatable air chamber. A tube connected to such expandable chamber is coupled to a fluid control system for inflation and deflation of the expandable chamber. 
     Traditionally, such expandable chambers are inflated by either pressurizing or deflating one or more of the cells in accordance with a predetermined control algorithm for providing a desired user support. Alternatively, the pressure can be controlled by a pump and switch under the control of any controller including a timer, a microcomputer or any other form of computer. In such arrangements, the individual expandable chamber or air cell have been located in desired seating configurations including the lumbar region and ischial regions of a user. In such seats a further practice has been to perforate an overlying trim material so that the seat cushion or seat back support surfaces will tend to breath. Leather or a suitable plastic material such as PVC, urethane, polyolefins or the like materials have been provided to give a level of so called breathability. 
     While suitable for their intended purpose such arrangements neither cool or heat a seat to meet desired uniform thermal comfort considerations. Other seating arrangements are known that will heat or cool a seat. Examples of such arrangements are set-forth in the following listed patents. 
     
       
         
               
               
               
             
           
               
                   
                   
               
               
                   
                 Patent No. 
                 Inventor 
               
               
                   
                   
               
             
             
               
                   
                 4,813,738 
                 Ito et al. 
               
               
                   
                 4,865,379 
                 Aoki et al. 
               
               
                   
                 5,723,845 
                 Parington et al. 
               
               
                   
                 5,921,314 
                 Schuller et al 
               
               
                   
                 5,948,297 
                 Haubner et al. 
               
               
                   
                 5,800,480 
                 Augustine et al. 
               
               
                   
                   
               
             
          
         
       
     
     It is also known to provide conductive extrudate articles configured with flat surfaces that will radiate heat when the articles are connected across an electrical source. Examples of such articles are set-forth in U.S. Pat. Nos. 4,954,695 and 5,181,006. 
     None of the aforesaid arrangements, however, provide for heating a support surface by use of a self heating expandable chamber such as an expandable chamber or air cell. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to a fluid support arrangement wherein the fluid inflatable bladder or air cell itself alone provides both thermal conditioning and a containment for a pressure medium for providing desired occupant support. Furthermore, the invention avoids the need for installation of separate heaters within the confines of seating and other types of occupant supports that embody such fluid inflatable bladders or air cells. 
     The invention for occupant support such as vehicle seating and mattress applications includes an expandable chamber such as an inflatable pressure adjustable air cell or bladder constructed from facing sheets of flexible, air-impermeable cell material sealed along adjoining marginal edges thereon. The facing sheets are comprised of conductive material dispersed as discrete particles embedded in polymeric material to define a self heating sheet that will produce electrical resistance heating of the surface for thermally conditioning the body contacting surface of a vehicle seat or other occupant support application while retaining pressurized fluid within the expandable chamber. 
     The expandable chamber conforms to an occupant supported thereon and the provision of the self heating sheet therein combines a pressure adjusted shape for support and heating. 
     A feature of the invention is to provide combined pressure and thermal heating functions in an expandable chamber comprised of two layers of material wherein at least one of the layers is polymeric material having conductive material formed as discrete particles embedded therein that will produce electrical resistance heating for thermally conditioning a body contacting surface of a vehicle seat, furniture seating, mattress or other occupant support application. 
     A further feature is to provide an expandable chamber such as an inflatable bladder or air cell; the expandable chamber having imperforate walls for containing pressure and a supply tube connected to a fluid system for controlling the pressure in the expandable chamber for providing occupant support and wherein one imperforate wall of the expandable chamber is comprised of a conductive material dispersed in a polymeric material to heat the supported occupant and wherein another imperforate wall of the expandable chamber is formed from electrically insulated, non conductive material and joined to the one imperforate wall to contain pressure within the expandable chamber. 
     A further feature is to provide such combined pressure support and heating in an expandable chamber including two sealed layers having electrical power leads formed thereon for directing electricity through a top layer formed of electrically conductive carbon loaded polymeric material. 
     A still further feature is to provide such pressure support and heating in a fluid support system wherein preselected expandable chambers are associated with at least one imperforate support surface formed as a layer of electrically conductive carbon loaded polymeric material that will conform to a supported occupant and when connected across a power source will provide heating. 
    
    
     DRAWINGS 
     A presently preferred embodiment of the invention is disclosed in the following description, and in the accompanying drawings, wherein: 
     FIG. 1 is a perspective view of a vehicle seat embodying an expandable chamber of the invention; 
     FIG. 2 is a diagrammatic view of a manifold suitable for use with the present invention; 
     FIG. 3 is an enlarged cross-sectional view taken along the line  3 — 3  of FIG. 1 looking in the direction of the arrows; and 
     FIG. 4 is a perspective view of another embodiment of the present invention including an electrically heated support layer conformable to an expandable chamber. 
    
    
     DETAILED DESCRIPTION 
     Referring now more particularly to the drawings, there is shown in FIG. 1 a vehicle seat  10  having a generally horizontal seat rest portion  12  and an upright back rest portion  14  that is coupled to and projects upwardly from the seat rest portion  12  in conventional manner to support an occupant in a seated position on the seat  10 . 
     The seat  10  is provided with an inflatable support system  15  according to the invention which includes one or more expandable chambers such as bladders or inflatable air cells  18 ,  20  mounted at preselected location within the seat  10 , preferably at least on the ischial region wherein fluid inflatable bladder or air cells  18  are shown in FIG.  1  and at the lower back or lumbar region of the backrest  14  wherein the fluid inflatable bladder or air cells  20  are shown. It should be understood that such locations are merely representative and the fluid expandable chambers can be placed in other seating locations such as bolsters, thorax regions and head rest regions (not shown). Furthermore, such expandable chambers or fluid inflatable bladders or air cells can be located on other occupant supports such as mattresses and beds at spaced transversely disposed points thereon or where ever occupant support and heating is desired. 
     While air cells are often used in such arrangements, the present invention can use fluids other than air to expand the expandable chambers. Such fluids can include liquids such as water and anti-freeze compounds; gases such as nitrogen, air, or other known inflatants. 
     As shown in FIG. 2, on or more of the expandable chambers or air cells  18 ,  20  has two sheets or layers  22 ,  24  of flexible plastic material, such as plastics, fabrics, or any other of the materials commonly used to construct inflatable fluid inflatable bladder or air cell for connection by tubes  27  to a pump  29 . The sheets  22  and  24  are imperforate. Their perimeters  25  are sealed together by a heat weld, ribbon weld, radio frequency welding, adhesives or the like. 
     The sheets or layers  22 ,  24  are formed from flexible material, such as plastics, fabrics, or any other of the materials commonly used to construct inflatable fluid inflatable bladder or air cell. Since the sheets  22 ,  24  are both imperforate and sealed along their perimeters  25 , they are configured to form an internal cavity  26 . 
     In the embodiment of FIG. 3, the flexible material in the top layer  22  is located below known seat covering material. The top layer is formed from material comprised of electrically conductive materials such as carbon black or metal particles dispersed in polymeric material having a thickness of 0.010 inches to 0.050 inches. 
     The polymeric material can be polypropylene, polyethylene, thermoplastic olefins and polyvinylchloride. Other materials suitable for mixing with the conductive particles can include materials suitable for waste recycling such as polyurethanes. 
     Representative formulations and characteristics of such material are set forth in U.S. Pat. Nos. 4,954,695; 5,181,006; and 5,985,976. 
     The lower layer  24  is formed from a non-conductive material that is an electrical insulator such as a polyolefin material or any other polymeric material that is non-conductive and compatible for joining to the top layer  22 . The lower layer has a thickness in the range of 0.010 inches to 0.050 inches. 
     In the illustrated embodiment of FIG. 3, electrical leads  28 ,  30  are connected by rivets  31 ,  32  at spaced points on the perimeter  25  so that electrical current from a suitably controlled supply  33  can be directed across the top layer  22  for causing the conductive particles therein to produce a resistance heating action for warming the exposed surface  22   a  of the top layer  22  of the expandable chamber such as fluid inflatable bladder or air cell  18 ,  20 . 
     In the embodiment of FIGS. 1 and 3 the fluid inflatable bladder or air cell are connected via suitable tubing to a controller  40  for a pneumatic seating comfort adjustment system of the type set-forth in U.S. Pat. No. 6,088,643 commonly assigned and incorporated herein by reference. 
     The controller has a manifold  41  comprising a housing  42  enclosing a chamber  42   a  constructed with multiple outlet ports  44  for connecting the chamber  42   a  to the inlet/outlet tubes of each individual cell or regional group of cells  18 ,  20 . Each outlet port  44  is provided with a control valve  46  for controlling the flow of fluid to and from one or more of the expandable chambers  18 ,  20 . Chamber  42   a  is also constructed with a single inlet port  48  which is connected to a feed tube  50  to receive pressurized fluid, in this case air, from the pump  29 . Pump  29  connects to a pump motor  54  connected to a pump drive  56  that is operated in response to air cell pressure under the control of a microcomputer  60 . 
     A supply valve  62  is provided in feed tube  50  to control the flow of pressurized fluid to the manifold. The manifold can be molded of a high strength plastic or rubber material or other suitable material. The plastic material arrangement can have many of its components integrally molded therein. It is preferred that it be as compact and lightweight as possible. However, the invention can be configured with other than lightweight components and other than with integral components. A common bleed or exhaust valve  64  is provided to selectively release pressure from the manifold chamber  42   a  through venting port  66 . The pressure in chamber  43  can therefore be adjusted by either actuating pump  52  or bleed valve  64 . 
     While the control valves  46  can be under the control of a suitably programmed microprocessor it will be understood by those skilled in the art that the control valves could constitute one or more manually actuated control valves. Still another arrangement could use the pump, operative alone, as the control of pressure in expandable chambers such as then one more fluid inflatable bladder or air cell  18 ,  20 . 
     In the embodiment of FIG. 4 a fluid pressurized expandable chamber such as a bladder or air cell  70  is shown having spaced sheets  72 ,  74  of suitable flexible material of the types set-forth below. They form one or more of the air cells of a suitable occupant support such as vehicle seating, furniture seating, mattresses or the like. A third shaped layer  76  is configured to overlie the upper sheet  72 . The layer  76  is comprised of electrically conductive particles dispersed in polymeric material having the same properties discussed with respect to the top layer  22  in the embodiment of FIG.  3 . In this embodiment the expandable chamber  70  is supplied through a conduit  78  as in the case of the expandable chamber shown in the first embodiment. The expandable chamber  70  is not self heating. Seat or occupant support surface heating, in this embodiment, is provided by connecting the third shaped layer  76  to a source of electrical power through leads  82 ,  84 , respectively connected by suitable fasteners such as rivets  86 ,  88  to opposite ends of the layer  76 . When it is desired to heat an occupant surface the leads are connect by a suitable controller or manual switching arrangement so as to produce electrical resistance heating for warming the upper surface  76   a  of the layer  76  that is shaped between the occupant and the supporting configuration of the expandable chamber  70 . 
     The disclosed embodiments are representative of a presently preferred form of the invention, but is intended to be illustrative rather than definitive thereof. The invention is defined in the claims.