Abstract:
An air cell support system for vehicle seat and mattress applications includes an air cell constructed from facing sheets of flexible material that are sealed along their marginal edges. One of the sheets is impermeable and the other of the sheets is perforated to direct air from the air cell for ventilating an occupant support surface while providing a source of pressure for inflating the air cell.

Description:
This invention relates generally to inflatable air cell systems for occupant support in seating and mattress applications and, more particularly, to the provision of a perforated wall in one or more air cells in a system for metered flow of fluid from the air cell to either heat or cool the seating or mattress application. 
     BACKGROUND OF THE INVENTION 
     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. An air tube connected to the air cells that in turn is coupled to an airflow control system for inflation and deflation of the air cell. 
     Traditionally, such air cells 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 comfort level. Alternatively, the pressure can be controlled by a pump and switch. In such arrangements the individual air cells 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. 
     
       
         
               
               
               
             
           
               
                   
                   
               
               
                   
                 U.S. Pat. No. 
                 Inventor 
               
               
                   
                   
               
             
             
               
                   
                 5,016,302 
                 Yu 
               
               
                   
                 5,524,439 
                 Gallup et al. 
               
               
                   
                 5,597,200 
                 Gregory et al. 
               
               
                   
                 5,626,021 
                 Karunasiri et al. 
               
               
                   
                 5,715,695 
                 Lord 
               
               
                   
                 5,800,480 
                 Augustine et al. 
               
               
                   
                   
               
             
          
         
       
     
     None of the aforesaid arrangements, however, provide for heating or cooling the fluid and also controlling the pressurization in known pneumatic support systems that utilize one or more air cells as a means for supporting an occupant and operable to vary the pressure in one or more or the air cells to provide individual occupant comfort. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to an air cell arrangement wherein the fluid supplied to the air cells provides both thermal conditioning and pressure control of the pressure medium for inflating the air cell arrangement to a desired comfort level while overcoming or greatly minimizing the objections of how to control the temperature of a covering material and to avoid the need for installation of heaters or coolers within the confines of seating and other occupant supports as associated with traditional seating and occupant support arrangements. 
     An air cell system according to the invention for occupant support such as vehicle seating and mattress applications includes an inflatable pressure adjustable air cell constructed from facing sheets of flexible, air-impermeable cell material sealed along their adjoining marginal edges. An upper surface of one or more of the air cells is perforated to provide leakage of air from the air cell during inflation thereof for thermally conditioning the body contacting surface of the vehicle seat or other seating or mattress application. 
     The perforated surface of the air cell advantageously simplifies and improves the flow of conditioned air into the supporting surface of a vehicle seat or other seat support or mattress application. 
     Since the support surface conforms to the occupant support thereon the provision of a perforated layer therein to leak air through the support surface of the seat combines both a pressure adjusted shape for supporting an occupant while directing conditioned ventilating air against such occupant so as to optimize both support and heating/cooling of a vehicle seat or the like. 
     A feature of the invention is to provide such combined pressure and thermal control in an air cell comprised of two layers wherein the top layer is perforated. 
     A further feature is to provide a first set of air cells with imperforate walls and a supply tube connected to a pneumatic adjustable system for controlling the pressure in one or more of the first set of air cells for providing primary occupant support and to provide a second set of air cells having a perforated layer thereon to leak conditioning medium through the support surface of an occupant support structure and wherein the second set of air cells is supported on the first set to provide supplemental occupant support while providing ventilating fluid to cause air movement to provide cooling or heating and to evaporate occupant perspiration. 
     A further feature is to provide such combined pressure support and thermal control in an air cell including two sealed layers and a third top layer having air flow perforations therein. 
     A still further feature is to provide such pressure support and thermal control in a pneumatic controlled pressure adjustable air cell support comfort system wherein preselected air cells are formed from imperforate layers and wherein a second set of cells are perforated to provide separate thermal conditioning of an occupant support. 
     Yet another feature of the invention is to provide an air cell having a combined pressure support and temperature conditioning capability and wherein the air cell is filled with reticulated foam to provide secondary support and to assure air flow patterns (either by pressure flow out or evacuation flow in) through a perforated layer of the air cells for directing heating and cooling medium to an occupant supported thereon. 
     Still another feature of the invention is to provide such an air cell pressure support and thermal conditioning system wherein the pressure for occupant support is provided by a first pumping system and wherein the fluid flow for heating and cooling medium is provided by a second pumping system. 
     Still another feature of the invention is to provide such air cells for occupant support and heating and cooling wherein conditioned air is evacuated e.g., drawn from the surface of the seat system and discharged through the surface of the occupant support. 
     Still another feature of the invention is to provide such support and conditioning systems wherein the conditioned air is supplied an outlet from a vehicle HVAC system and is discharged through the surface of the seat system. 
    
    
     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 air cell system of the invention; 
     FIG. 2 is a cross-sectional view taken along the line  2 — 2  of FIG. 1 looking in the direction of the arrows; 
     FIG. 3 is a view like FIG. 1 including a primary air cell system for supporting an occupant and a secondary air cell system for providing combined occupant support and thermal control; 
     FIG. 4 is a sectional view taken along the line  4 — 4  in FIG. 3 looking in the direction of the arrows; 
     FIG. 5 is a plan view of another embodiment of the invention shown in association with a pneumatic comfort control system for occupant support; 
     FIG. 6 is a transverse cross-sectional view taken along line  6 — 6  of FIG. 4; FIG. 7 is a view of a control valve for the embodiments shown in FIGS. 1-5; 
     FIG. 8 is a schematic view of a controller for controlling the control valve of FIG. 7; and 
     FIG. 9 is a perspective view exploded to show another embodiment of the invention in a seating application; 
     FIG. 10 is an enlarged fragmentary view in perspective of another embodiment of an air cell including the present invention; 
     FIG. 11 is a perspective view partially section of another embodiment of a ventilating and load support air cell; and 
     FIG. 12 is a diagrammatic view of still another embodiment. 
    
    
     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 air cell system  15  according to the invention which includes one or more inflatable air cell(s)  18 , 20  mounted at preselected location(s) within the seat  10 , preferably at least on the ischial region wherein air cells  18  are shown in FIG.  1  and at the lower back or lumbar region of the backrest  14  wherein the air cells  20  are shown. It should be understood that such locations are merely representative and the air cells can be placed in other seating locations such as bolsters, thorax regions at air cells  21  and head rest regions (not shown). Furthermore, such air cells can be found on other occupant supports such as mattresses and beds at spaced transversely disposed points thereon or where ever occupant support and cooling/heating is desired. 
     As shown in FIG. 2, each air cell  18 , 20  is constructed from 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 air cells for connection by tubes  27  to a pump  29 . The sheet  20  is imperforate and the sheet  22  is perforated at  25  for flow of thermal conditioning air (heated, cooled or ambient) for either heating or cooling the seat surface. Flow through the perforations provides ventilating fluid to cause air movement at the occupant support surface and such movement in part serves to evaporate occupant perspiration. 
     As shown in FIG. 1 at air cell  18   a , the perforations  25  can be formed as slits  26 . Alternatively, as shown at air cell  18   b  in FIG. 1, the perforations are can be holes  28 . The holes  28  can be formed by laser, needle or other perforation methods. 
     In the embodiment of FIGS. 3 and 4 a first set of air cells  30  are constructed from two sheets or layers  32 ,  34  of flexible air cell material, such as plastics, fabrics, or any other of the materials commonly used to construct inflatable air cells. The sheets  32 ,  34  are both imperforate and form an air cell cavity  36 . A second set of air cells  31  are supported by the first set of air cells  30 . These cells have a perforated top layer  33  that will direct heating or cooling fluid to the occupant and serve as a supplemental support. 
     In FIG. 4 a further embodiment is shown of a diagrammatic representation of a seat comfort adjustment system  37  including air cell support and thermal conditioning wherein the pressure for occupant support is provided by a first pumping system  38  and wherein the fluid flow for heating and cooling is provided a second pumping (or blower) system  39 . 
     First air cells  30  are provided that are connected to the seat comfort adjustment system  37  including the first pumping system  38 . These air cells  30  do not provide heating or cooling but provide the primary occupant support. Additional air cells  33  are arranged between and are supported on the air cells  30  and the air cells  33  are connected to the second pumping system  39  independent of the first pumping system  38 . In such case the source of fluid can for example include a pump connected by a conduit  43  across a suitable control valve arrangement  45  of a type to be described and wherein the conduit  43  can be connected to a cavity in which is located a heater  47  or a cold source  49  such as an evaporator coil of a refrigerant system or a thermoelectric device that can be either operated as a heater or a cooler depending upon the electrical connections there across. Alternatively, a source of ambient air can be used rather than cooling (which can be harmful, in excess, to the back). 
     In the embodiment of FIGS. 1 and 2 and FIG. 3, the air cells  18 ,  20 ,  21 ,  30  and  31  are connected via suitable tubing to a controller  40  for a pneumatic seating comfort adjustment system of the type set-forth in copending U.S. patent application Ser. No. 08/808,511 incorporated herein by reference. 
     The controller has a manifold  42  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. Each outlet port  44  is provided with an outlet valve  46  for controlling the flow of fluid to and from the air cells. In this embodiment, the sensor is a pressure sensing transducer  47  that is operatively connected in the manifold to sense the pressure in the manifold chamber  42   a  and generate a signal indicative thereof. 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 a pump  52  corresponding to either the pump  38  or the pump  39 . Pump  52  has a pump motor  54  connected to a pump drive  56  that is operated in response to air cell pressure under the control of 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  43  through venting port  66 . The pressure in chamber  43  can therefore be adjusted by either actuating pump  52  or bleed valve  64 . 
     As shown in the diagrammatic control circuit of FIG. 8, valves  46  are actuated by an electrical signal from a valve drive  65  and are designed for low power, low fluid resistance operation. More specifically, each valve  46  is an adaptation of highly efficient valves used in medical applications such as MEMS (micro electromechanical system) type or piezoelectric actuated valves. The bodies and valve seats of such designs are easily moldable with and can be integrated as lightweight components within the manifold body or on a PC board. Individual valve bodies can be designed for stacking assembly to form the manifold of this invention. In addition to a piezoelectric actuated valve other low energy actuatable valves are contemplated by the present invention including but not limited to electrically pulsed reed valves; valves having an actuator configured of nickel titanium alloy such as Nitinol; magnetic inductive type valves or fluidic control valves so long as low energy consumption will operate the valve in on-off positions in which the flow from an inlet to outlet will satisfy the flow requirements of the pressure adjusted air cells in a given pneumatic system for controlling a seating surface such as a seat, chair or bed to provide contouring, movement, support and/or comfort at a user interface. The importance of the use of such a valve arrangement in the present invention is that, in the past, pressure adjusted systems have utilized solenoid actuated valves to open and close an air cell to a pressure source for inflating the air cell or to a relief path for deflating the air cell. In such applications, the size of the control package is difficult to contain within the confines of a vehicle seat structure. Furthermore, power consumption is a problem since the major power consumers in the system combine power flow for operation of a motor driven pump and the power flow for operating the solenoids connected to the mechanical valve components. 
     Also, another advantage of reduced power is where power consumption is a rigid design constraint, as in the case of battery powered systems. The orders of magnitude decrease in valve power consumption provided by the present invention becomes a significant, and heretofore unrecognized advantage since a smaller power source can be used for lower cost and reduced weight; fewer modifications to wiring harness designs in vehicular operations are required and less heat is generated in systems where heat build up can be disadvantageous as for example in space shuttle and other vehicular operations where the system is used in a controlled environment. 
     Another feature of the valves  46  is that they have high flow rate capability that is important in applications where the air cell volume is relatively large, e.g., in the operation of the energy absorbing components of the system to be described. In such system the response is required to be non-subtle, e.g., pressure adjustments in the cell are made rapidly. In such applications the large flow rate is especially advantageous. However, in all applications, the flow rate will directly impact system energy dissipation. The activation time (time required for the system to reach a desired programmed target) will depend upon the flow rate of the valves, pump flow rate capacity, and volume of the target air cell(s). If the flow rate of an individual valve is low, more time will be required to achieve the target; a pump will be required to run for a longer period of time in which its power consumption over greater time will produce greater energy dissipation. Another disadvantage of such prior art lower flow rate valves is that they are pneumatically lousy since pressure drop across the valves will be higher and usable pressure at the outlet of the valve will be less. 
     The Control 
     The active parts of the system of this invention namely: the outlet valves  46 , the pressure transducer  47 , pump  52 , as well as bleed valve  64  and supply valve  64  are interconnected electrically to the microcomputer unit  60  which controls the operation of the system. The microcomputer  60  can be a commercially available microcomputer such as the 68HCO5 variant manufactured by Motorola. A microcomputer as used herein includes all subsystems and peripheral components as is well known to those skilled in the art. 
     The microcomputer  60  has access to non-volatile memory, which has been programmed to provide a predetermined comfort standard such as the algorithm described in U.S. Pat. No. 5,283,735. These data can be compiled and coded for use with individual air cells or regions of air cells. Data sensed by transducer  47  is compared to the comfort standard and an actuation signal is generated which actuates the system to compensate for any differential between the programmed comfort level and the sensor generated data. 
     In order to operate each cell or group of cells independently to provide an extensively adjustable system, the microcomputer  60  must also be programmed to actuate the outlet valves  46  to isolate a selected air cell or group of air cells in communication with the manifold. The actuation is controlled in closed loop fashion to allow the pressure in the chamber  43  to equalize with the pressure in the air cell or cells with which it is communicating. On an instantaneous basis there is a closed system among the connected air cell(s), the feed tube  68 , the chamber  43 , and the fluid supply thereby allowing the sensor  47  to provide data from the closed system and to provide adjustment of the pressure in the isolated air cell(s) by the microcomputer  66  to the desired comfort or pressure level. 
     Operation 
     The operation of the invention will be understood to have application to either the embodiment of FIGS. 1 and 2; the embodiment of FIGS. 3 and 4; the embodiment of FIGS. 5 and 6; the embodiment of FIGS. 9 and 10 and the embodiments of FIGS. 11 and 12, respectively, either described or to be described herein. The controller furthermore can be manual embodying a pump and switch or embody the controllers shown in FIG.  6  and in FIG. 7 of U.S. Ser. No. 8/808,511 U.S. Pat. No. 6,098,000 commonly owned by the assignee of the captioned invention and incorporated herein by reference. It should be understood that the operation of the target pressure control variants to be described herein apply equally well to systems in which the air cells can be independently positioned or remain in a predetermined position on a support surface of a vehicle seat or the like. 
     In operation, the microcomputer  60  will condition the valve drive  65  to in turn open a valve  46  interconnecting a selected air cell or air cell group, such as one or more of the ischial air cells  18 , with the manifold chamber  22  and allow the pressure in the selected system to settle out. The time to let pressure equalize is “pressure settling time”. After the settling time, the pressure is sensed and a signal is sent to the microcomputer  60  for comparison with the preprogrammed comfort data. The microcomputer  60  then generates a signal relative to the difference in the comfort level sensed to the programmed comfort level and initiates a flow of fluid to or from the selected cell system to reduce the difference to zero. This sequence of operations is then repeated “n” times until each of the air cell systems are sensed and adjusted. 
     The controller  60  controls fluid flow from a pressure source that can be an electric motor driven pump such as pump  29  in the first embodiment and a source of pressurized conditioned fluid such as cooled air directed across a refrigerant coil  67  or other cold source or a source of heated pressurized air that is supplied by a pump and including suitable heat source such as an electric heater  69  for heating the fluid prior to passage through the air cells  18 ,  20 ,  21  in the embodiment of FIG. 1 or the air cells  30  and  31  in the embodiment of FIG.  3 . The plurality of control valves  46  are operative to control the supply of pressurized fluid to each of the air cells to simultaneously inflate the air cells for comfort control and to provide for a flow of cooling air through either the slits or holes for cooling the respective seating or support surfaces. 
     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 one more air cells. 
     In the aforesaid arrangements the pump for a system that supplies perforated cells for ventilating and supporting an occupant must be properly sized to supply adequate pressure and flow to both keep the air cell inflated to its desired occupant support pressure while preventing excessive air flow therefrom. A desired balance is to provide enough air for cooling or heating without having to expend excessive energy in the pumping process. 
     In one working embodiment that is only illustrative, the perforated layer of an air cell was selected having a thickness of 0.010 inches; and perforations of 0.045 inch holes and a the air flow is provided by a blower (pump) having a capacity of 2-30 cfm. 
     In other arrangements the parameters for design typically might include the following: 
     
       
         
               
               
               
             
           
               
                   
                   
               
               
                   
                 Component 
                 Design Parameter 
               
               
                   
                   
               
             
             
               
                   
                 Air cell bladder 
                 TPU (Thermoplastic Urethane) .010″ 
               
               
                   
                   
                 to .025″ (Equivalent materials include 
               
               
                   
                   
                 PVC, Nylon or Thermoplastic 
               
               
                   
                   
                 Elastomers with or without fabric 
               
               
                   
                   
                 reinforcement and carbon filled TPU 
               
               
                   
                   
                 film) 
               
               
                   
                 Hole Size 
                 .010″-.050″ and spaced approxi- 
               
               
                   
                   
                 mately 1 inch on centers or sufficient 
               
               
                   
                   
                 to allow 15-25 cfm airflow. 
               
               
                   
                   
               
             
          
         
       
     
     Other Embodiments 
     In the embodiment of FIGS. 5 and 6 a separately inflated ventilation duct  70  is provided that is interposed between inflatable air cells divided into air cells  71 ,  72 ,  73 ,  74 , and  75 , respectively providing adjustable pneumatic support at lumbar zones  71 ,  72 ,  73  and at ischial zones  74  while air cells  75  provide thigh support. The air duct  70  is formed of an imperforate wall  76  and a perforated wall  77  and is positioned between the air cells 71-77 in. low/no pressure regions of body contact, and therefore, remain open to air circulation and movement of an occupant. The duct  70  can be formed separately but as part of a normal mat welding process wherein the sheets are joined by known methods to form the respective air cells. It is possible, however, to make a mat with or without the duct. The duct  70  is supplied from a suitable conditioned air source  79  and the other air cells are pressure controlled for occupant comfort as discussed in the previous embodiments. 
     In the embodiment of FIGS. 9 and 10 a vehicle seat  80  is shown including a perforated trim cover  82  covering a porous foam pad  84  for distributing air from a three ply pressure support and air flow air cell  86 . The seat  80  further includes a seat form  88  and a suspension and frame  90  that can be configured as set-forth in copending U.S. Ser. No. 09/076,184 U.S. Pat. No. 6,070,942 filed May 12, 1998 for Seating Assembly and Method of Making Same and incorporated herein by reference. In this embodiment, as best shown in  10 , each air cell  86  includes three walls  92 ,  94  and  96 . The lower walls  92 ,  94  are imperforate and are supplied by a tube connected to one of the control valves described above for providing a predetermined occupant support pressure within a chamber  98  defined within the lower walls  92 ,  94 . The uppermost wall  96  cooperates with the wall  94  to define a fluid cavity  100  that is communicated with a suitable source of conditioned fluid  102  such as the source of fluid  39  supplied to the chamber enclosing heater  47  or cold source  49  (or ambient air) shown in the embodiment of FIG.  4 . Likewise the chamber  98  can be supplied by an independent pressure source  104  such as the pressure source  38  shown in FIG.  4 . 
     In the embodiment shown in FIG. 11 an air cell  120  is illustrate that includes two walls  122 ,  124  forming a chamber  126  there between occupied by a filling of reticulated foam  128 . In this embodiment the upper wall  122  is perforated at  123  as previously described and the chamber  126  is connected to a tube  130  for supply fluid to the chamber  126  for providing both occupant support and a flow of air through the seating surfaces to simultaneously heat, cool or condition the occupant supported by the pressure in the chamber  126 . The provision of the reticulated foam  128  has a resiliency selected to provide a secondary occupant support when the chamber  126  is deflated. Furthermore, such reticulated foam  128  will maintain the perforations  123  open to assure fluid flow there through. If desired the cooling action can be obtained by providing a suction pump  132  connected to the tube  130  for drawing heated or cooled air from the interior of a vehicle that either has ambient air or heated or cooled air as supplied by a known HVAC (heating, ventilating and air conditioning) system that will act as a source of either cooling or heating fluid or vent air. In this case the suction pump  132  can be controlled by suitable valves in accordance with a desired support or cooling program. The invention also contemplates the option of a 3 layered cell, top one perforated and reticulated foam between the top 2 layers. 
     In the embodiment of FIG. 12 a support and air conditioning system  140  is shown wherein the conditioned air is discharged from the surface  142  of a occupant support system  144  of an air cell  146  that is connected directly to the outlet of an HVAC system  150  by suitable conduits  152 . 
     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.