CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of provisional patent application Serial No. 61 /698,233 filed September 7, 2012 and is related to International Patent Application No. PCT/US201 1 /058582 filed October 31 , 201 1 , both of which are incorporated herein by reference.

BACKGROUND

The invention relates generally to support surfaces that facilitate blood flow and prevent tissue breakdown and more particularly to a cushion that has relatively uniform restoring forces when deformed under loads from of a user and to a valve that can be employed with the cushion to vent air when the user is seated to achieve desired, predetermined immersion into the cushion to provide optimum seating characteristics including uniform restoring forces.

Individuals confined to sitting, for example in a wheelchair run the risk of tissue breakdown and the development of ischemia induced sores, which are extremely dangerous and difficult to treat and cure. For example, when seated much of the individual's weight concentrates in the region of the ischia, that is, at the bony prominence of the buttocks, and unless frequent movement occurs, the flow of blood to the skin tissue in these regions decreases to the point that the tissue breaks down. When lying down, the hip region may protrude deeper into the mattress than the adjoining waist or thigh regions and as a consequence the supporting forces exerted by the mattress would be greater at the hips than at the thighs or waist, for example. Any skin area where there is sustained deformation suffers reduced blood flow and the skin does not receive sufficient oxygen and nutrients.

It is desirable to have a support surface that applies generally uniform supporting forces, for example, a generally uniform counter force on the tissue of the ischial area of user positioned on a cushion. When a cushioning structure is deformed while supporting a person, it is desirable to have a constant restoring force that exerts equal forces over a broader area of the body minimizing deformation of the soft tissues and help prevent skin and tissue breakdown by facilitating blood flow in the contacted area.

Cellular cushions generally provide the most uniform distribution of weight and thus provide the greatest protection from the occurrence of pressure sores. Inflatable cellular cushions have an array of closely spaced air cells that project upwardly from a common base. Within the base the air cells communicate with each other, and thus, all exist at the same internal pressure. Hence, each air cell exerts essentially the same restoring force against the buttocks, irrespective of the extent to which it is deflected. U.S. Patent No. 4,541 ,136 shows a cellular cushion currently manufactured and sold by assignee, ROHO, Inc. of Belleville, Illinois, for use on wheelchairs.

In general, inflatable cushions or inflatable air cell cushions employ a standard inflation or fill valve for inflating the cushion. These valves, referred to Schrader valves, are customarily used on pneumatic vehicle tires. The valve stem has a threaded cap that is removed and then the air source connected. If the cushion is over inflated, the user must depress the concentric pin and bleed air from the cushion. After the cushion is inflated to a satisfactory level, the valve step cap is reapplied. As can be appreciated, this can be a difficult procedure for a disabled individual.

A variation of the cellular cushion provides isolated zones and also with cells of varying height. By varying the volume of air between zones, for example, one can accommodate for skeletal deformities while still maintaining satisfactory protection against pressure sores. U.S .Pat. No. 4,698,864 shows zoned cellular cushion with cells of varying height. U.S. Patent No. 5,163,196 and U.S. Patent No. 5,502,855 disclose other zoned cellular cushions having isolated inflation zones. Generally these cushions include a fill valve of the Schrader design. However, different types of valves used to maintain air volume in the various inflation zones. Two representative embodiments are shown in U.S. Patent No. 6,687,936 and U.S. Patent No. 6,687,936, respectively. These valves, which can be referred to broadly as slide valves, when employed for example with a zoned cushion having a plurality of inflation zones, provide an easily manipulated valve assembly which can be used to allow fluid communication between two or more zones or can be used to isolate the zones. In certain aspects, the cushions can be filled through the slide valves.

Although the needed proficiency in their use is not difficult to obtain, there are some circumstances in which a user could benefit from a support surface, such as a cushion or a mattress or mattress overlay or pillow, which is even simpler or more convenient to use that these cushion and valve combinations. These circumstances can arise, for example, where the user is newly disabled and perhaps overwhelmed by the attendant change in lifestyle. Or, for example, if the user just does not have the mental acumen to properly use an adjustable cushion. An example may be a person suffering from dementia or Alzheimer's.

It would therefore be advantageous to have a support surface, such as a cushion or mattress or pillow, with a self-adjusting valve that allows a user rest on the support surface and reach an optimal immersion level without the manipulation of a valve

SUMMARY

In one aspect, a cushion with having a base and a support surface comprising a plurality of individual air cells and a valve in fluid communication with the plurality of air cells that allows the controlled expulsion of air until a user positioned on the cushion is optimally immersed in the cushion and also controls dampens dynamic air flow and pressure spikes resulting from movement of the seated user. In one aspect, a cushion with a plurality of individual air cells that compress and expel air through a valve in a controlled manner so that the user is optimally immersed in the cushion and when the user gets off of the cushion, the valve allows ingress of air into the cushion air cells to restore the fluid volume of the cells.

In one aspect, a cushion with a support surface comprising a plurality of compressible support elements, and a valve in fluid communication with the plurality of compressible suspension elements that allows the controlled expulsion of air until a user positioned on the cushion is optimally immersed in the cushion and also controls dampens dynamic air flow and pressure spikes resulting from movement of the seated user.

In one aspect, the valve comprises an expansion valve design, through multistage pressure reduction, which dampens the dynamic air flow and pressure spikes that result from movement of the seated user.

In one aspect, the valve comprises a labyrinth seal design, through multistage pressure reduction, which dampens the dynamic air flow and pressure spikes.

In one aspect, the valve comprises a pressure responsive compression spring that controls the expulsion of air from the cushion and, consequently, controls the immersion depth of the seated user.

In one aspect the valve comprises a valve ball and ball seat seal that cooperate to control the expulsion of air from the cushion and, consequently, controls the immersion depth of the seated user.

In one aspect the valve comprises at least on air ingress structure that allows air into the cushion when the load of the seated user is removed.

In one aspect the important operative parts of the valve are molded from a plastic material. BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is perspective view of one aspect of a cushion employing one aspect of the disclosed valve;

Fig. 2 is side cross-sectional schematic of one aspect of the valve;

Fig. 3 is an exploded perspective view of another aspect of a cushion employing an aspect of the disclosed valve;

Fig. 4 is a bottom plan of a support surface of the cushion of Fig. 3;

Fig. 5 is a side cross-sectional schematic of another aspect of the valve;

Fig. 6 is end plan view of one aspect of a seal housing for the valve;

Fig 7 is end plan view of another aspect of a seal housing for the valve; and

Fig. 8 is end plan view of another aspect of a seal housing for the valve. DETAILED DESCRIPTION

Although the cushion and valve assembly is disclosed relative to the therapeutic cushion and mattress environment, it will be understood that the disclosed invention, particularly the self-controlling valve, has applications in other environments, for example, air mattresses, inflatable rafts, inflatable toys, furniture cushions and mattress of various designs. The valve is designed to allow controlled release of air from the device to which it is attached. The device may be referred to generically as a cushion herein and in the appended claims.

In any event, one aspect of a cushion is indicated generally by numeral 20 in Fig. 1 . It will be understood that the term cushion, as used herein, is intended to include cushions for seating, larger embodiments often referred to as mattresses or mattress overlays, pillows, pads or any other such support surfaces for supporting the anatomy of a user.

Cushion 20 comprises a base 22, an array of individual, interconnected inflatable air cells 24 arranged across the base. As show, cells 24 are arranged in longitudinal and transverse rows. Cushion 20 may be constructed in accordance with the principles disclosed in the assignee's U.S. Patent No. U.S. Patent No. 4,541 ,136, which is incorporated herein by reference. The individual air cells may be divided into inflations zones, as taught by U.S. Patent No. 5,163,196 and U.S. Patent No. 5,502,855, which also are incorporated herein by reference. It will be appreciated that the use of any acceptable type of inflatable air cell cushion or mattress is contemplated. The air cells may be of any appropriate configuration and arrangement. The present invention can be used with a cushion employing any preferred configuration of cells 24, that is, for example, cells having any number of fins or sides, cells having no fins, for example, cylindrical, cubical cells or rounded cells. Cushion 20 includes a conventional air-filling valve 26 through which the air cells are inflated. Cushion 20 also includes a self-adjusting valve 28 in fluid communication with the air cells. The construction and function of valve 28 will be described in greater detail hereinafter.

In any event, to prepare cushion 20 for a user air-filling valve 26 is opened and air is pumped into it with a pump which connects to the valve 26. Enough air is pumped into the cushion 20 to exceed the requirements for supporting the user. Because the air cells are interconnected, the cells will reach equilibrium when fully inflated. The valve 26 then is closed and the pump removed.

Next the over-inflated cushion 20 is place on a supporting surface upon which it is to rest when supporting a user. The user then sits upon cushion 20 in the location he or she expects to assume. The seated user exerts force on air cells 24 and the air pressure opens valve 28 to allow air to be expelled through valve 28. The buttocks of a seated user, for example, are immersed into the support surface defined by the air cells. As air is released through valve 28, the user's buttocks sink deeper and deeper into the array of cells 24, and the cells tend to envelop and assume the contour of the buttocks. Sufficient air is released to bring the region of the ischia to within about ½ inch of the base 22. Of course, as air flows out of the cushion 20 all of the cells 24 remain at essentially the same internal pressure because they are interconnected.

When the user achieves the desired immersion and the volume of air within the cells is decreased, thereby decreasing the air pressure on valve 28, the self-adjusting valve 28 closes. As will be explained, the valve 28 is designed to close, or shut off air flow, at a predetermined drop in pressure in the valve such that the seated user is optimally immersed in cushion 20. By controlling the surface area of cushion 20 and the characteristics of valve 28, as will be explained below, an optimum pressure of about 30 to about 50 mmHg within the cushion can be achieved.

One embodiment of valve 28 is shown in detail in Fig. 2. Valve 28 is inserted in tube 30 and is in fluid communication with the air cells of the cushion in any acceptable manner. Alternatively, valve 28 can be in fluid communication with a cell through a hole in the cell. A separate conduit or tube is not required.

In one embodiment, valve 28 comprises a labyrinth seal design that dampens dynamic air flow and pressure spikes. In general, air pressure from cushion 20 with a seated user causes a valve ball to open against the spring compression force in the valve body. The dynamic air pressure resulting from movement of the seated user is dampened by using of a labyrinth multistage pressure reduction configuration. Moreover, the compression force of the spring can be varied to set optimal seating or immersion characteristics. In another aspect, and as will be described, the sealing characteristics of the ball valve and a valve O-ring seal or gasket, can be varied to set optimal seating or immersion characteristics as well. A combination of adjustments of the spring compression characteristics and the ball and O-ring sealing characteristics allows for exquisitely fine adjustments of the seating characteristics through valve 28.

Referring to the cross-sectional schematic Fig. 2, valve 28 has a casing 32 with a posterior section 34 including an elongated extension 36. Casing 32 can be of any configuration, however, a cylindrical, circular or disk-like configuration works well, as seen in Figs. 2 and 5. Extension 36 can be tubular with an internal bore 38. Circumferential barb 40 functions to secure the extension within tube 30. Tube 30 is in fluid communication with the interior of a cell and hence, bore 38 and valve 28 are in fluid communication with the interconnected array of individual inflation cells.

Valve 28 includes a first labyrinth ring 42, a second labyrinth ring 44, a third labyrinth ring 46 , a ball housing 48 defining an inner bore 50 and a ball retainer 51 having a central opening 52 therein inserted into the anterior opening into bore 50. It will be noted that second labyrinth ring 44 includes a slightly beveled forward face 53 which allows the second labyrinth ring 44 to be constructed from a rigid plastic and still be inserted into ball housing 48 with an airtight fit. Hence, this design allows relatively rigid plastic parts to be assembled.

The various components of valve 28, described above, define a series of labyrinth chambers to dampen air flow. Bore 38 also is in fluid communication with the labyrinth chambers inside the valve casing. For example, air flow from the interior of the cushion follows a path shown by arrows A1 . At stricture 54 the fluid flow is constricted; there is a significant pressure drop as the fluid flow expands into chamber 56; again there is constriction at stricture 58 and a pressure drop at chamber 60. There is a third constriction of flow at stricture 62 and a pressure drop at chamber 64. Ultimately, the reduced fluid flow at chamber 65 contacts a valve ball 66. Valve ball 66 is slidingly engaged within inner bore 50 of the ball housing. In one aspect, ball 66 is made from acetal, for example, Delrin ^® Acetel Resin.

Bore 50 is a substantially cylindrical bore defined by ball housing 48. There are a series of equally spaced apart ball support ribs 68 extending inward from the wall of bore 50 to keep ball 66 properly positioned within the bore. There is a valve seat 70 at one end of bore 50 and ball retainer 51 at the opposite end. It will be understood that there is an O-ring seal 72 around valve seat 70

Valve ball 66 is biased again valve seat 70 and O-ring 72 by valve spring 74, which extends longitudinally within bore 50.

Since valve 28 comprises the labyrinth configuration, the step down in pressure is such that the force required to open valve 28 is greatest when the user at first sits on the cushion and begins to immerse the buttocks and ischial area into the cushion. This generally constant force on the cushion generates fluid pressure within the cushion that over comes the biasing force against the valve ball 66 and valve ball 66 moves away from valve seat 70, thereby opening the valve and allowing air to escape through bore 50 and out of opening 52 in ball retainer 51 . When the restoring force of the air cells against the seated user's body overcomes the fluid pressure, the pressure against ball 66 is reduced and ball 66 is biased against valve seat 70 and O-ring 72 forming a tight seal and thereby closing the valve, maintaining the appropriate or desired immersion depth. Once the user is seated, the pressure reducing labyrinth configuration within the valve keeps air from leaking under dynamic pressure changes that may result from user movement. In any event, the valve spring is such that it will keep the valve closed and not allow the user to bottom out.

As long as valve ball 66 is biased against valve seat 70 and O-ring 72, no air will escape through the valve. However, when a predetermined fluid pressure resulting from the user sitting on cushion 20 is applied against valve ball 66 by the air flow through the labyrinth, which can be regulated or controlled by variation or modification of various structural elements within the valve, as will be described immediately below, valve ball 66 is urged away from valve seat 70 and air will escape from valve 28 through opening 52. There are several mechanisms by which the opening and closing of valve 28 can be controlled. That is, there are a number of ways the immersion depth of a seated user and control pressure spikes within the cushion can be adjusted through valve 28. It will be appreciated that the novel construction and materials used in the valve will allow the sensitivity of valve 28 to be controlled so as to allow opening of the valve at pressures as low as about 15 mmHg.

For example, valve spring 74 has a preselected compression force depending upon the surface area of the cushion and the estimated weight of the user. The valve spring is selected so that sufficient air escapes the cushion resulting in emersion into the cushion until the user's anatomy is about one-half (1 /2) to (1 ) inch from the surface on which the cushion is position, for example, a wheelchair seat. Also, valve spring 74 is selected so that the fluid pressure within the cushions about 30 to about 50 mm Hg, resulting in a uniform restoring force against the seated user's body.

Furthermore, the linear dimension of bore 50 with valve seat 70 at one end of the bore and ball retainer 51 at the opposite end can be adjusted to change the compression characteristics of spring 74 positioned in the bore. For example, bore 50 can be shortened to increase the compressive force of spring 74 on ball 66, or lengthened to decrease the compressive force.

Also, in one aspect, O-ring 72 is comprised of silicone having a Durometer hardness of approximately 50 to approximately 60. It has been discovered that an O-ring seal within this range of hardness allows for the best seal. The hardness of the O-ring can be manipulated to change the opening and closing characteristics of valve 28. Furthermore, because of sealing characteristics of O- ring 72, the entire valve 28 can be constructed of a plastic or polymer material, including ball 66 and ball seat 70 and still achieve operational and sealing characteristics heretofore limited to machined metal valves.

Referring to Figs 3 and 4, an alternative embodiment of a cushion is indicated generally by reference number 80. It will be appreciated that cushion 80 is a representative embodiment of any cushion that employs a support surface other than an inflatable air cell cushion or support surface, as described above.

In any event, cushion 80 comprises a support surface 82, a cover, which in the illustrated embodiment comprises a cover bottom 83 and a cover top 84, and a valve 85. Support surface 82 comprises a resilient pad having anterior section 86 and a posterior section 87. Generally, the anterior and posterior sections of the support surface are formed from a compressible, resilient material such as polyurethane foam.

Both anterior section 86 and posterior section 87 comprise a plurality of cells or suspension elements 88 arranged in lateral and transverse rows across the expanse of the sections, as seen in Fig. 4. It will be understood that the support surface, whether a single piece or comprising an anterior or posterior section, can be made and function in accordance with the principles disclosed in the assignee's U.S. Patent Nos. 7,424,761 and 7,681 ,264, both of which are incorporated herein by reference.

In one aspect, each suspension element 88 has a displaceable, load- bearing surface 90, a first end wall 92 and a second end wall 94. The load bearing surface and respective end walls define an inner chamber 96. Chambers 96 can be empty or filled, for example, with foam or gel or other material to change the support characteristics of the cushion or modify the air egress and ingress characteristics of the cushion. Moreover, chamber 96 can have a thin wall or skin over them with a small hole in the wall to vary or control the compression characteristics by controlling the fluid flow from the chamber under force. In one aspect, the material thickness of the load-bearing surface 90 is greater than the material thickness of the end walls so that the end walls can distend outwardly when force is applied to the load-bearing surface and the load- bearing surface depresses or collapses or otherwise deforms in a uniform manner under load. The suspension elements 88 cooperate to form a displaceable surface that, when deformed, exerts a restoring force that is generally constant irrespective of the extent of the deformation. Support surface 82 applies a generally uniform supporting pressure against an irregularly contoured body supported on the cushion. In general, posterior section 87 may be formed from stiffer foam than anterior section 86 such that posterior section 87 will have a greater restoring force than the anterior section. In most situations, the posterior section of a cushion supports at least fifty percent (50%) of the seated user's body weight. A firmer posterior section provides more support and a feeling of greater stability. The support surface construction is such that the cushion will not bottom out under a seated user. Although shown as two sections, it will be understood that support surface 82 can be a single or unitary piece as well.

An anterior wall 98 of the support surface defines a cavity 100 for housing valve 85, as will be described below. Both anterior section 86 and posterior section 87 comprise a plurality of cells or suspension elements 88 arranged in lateral and transverse rows across the expanse of the sections. In one aspect the suspension elements 88 have a generally arch-like cross-sectional configuration to facilitate a controlled buckling function.

In the illustrated embodiment there is cover top 84 that covers the top surface of support pad 82 as well as cavity 100 and provides openings 106 for valve 85 in fluid communication with the atmosphere and in fluid communication with the interior of the cushion in any acceptable manner. Cover top 84 generally can be a vacuum formed polyurethane film having a thickness of about 0.020 inches in the exemplary embodiment. In another embodiment, the cover top can have a fabric bound to the polyurethane film, providing a cover top over the support surface that is easily cleaned by wiping down with a mild cleaning solution. Cover bottom 83 has a configuration complementary to the suspension elements generally comprises vacuum formed plastic film, as well, having a thickness of about 0.020 inches in an exemplary embodiment. Cover bottom 83 duplicates the configuration of the suspension elements 88 and seats the suspension elements. This arrangement reduces the volume of the cushion and, therefore, reduces the amount of air within cushion 80, making the expulsion of air easier to control. It also eliminates the user sensation that the cushion feels like a balloon. This arrangement also prevents or controls splaying of the suspension elements under load. Cover top 84 and cover bottom 83 can be joined together, either by sonic, RF welding, gluing or other appropriate means sealing them together around the edges of the cushion with support pad 82 inside. The cushion then is impervious to gas or fluids.

The cushion can have any desired configuration, with the illustrated embodiment being a rectangle. The dimensions of cushion 80 can vary depending upon the size of the surface on which it will be used or depending upon the size of the user. A cushion having dimensions of eighteen (18) inches by eighteen (18) inches is one representative embodiment. A larger, heavier user would employ a cushion having greater surface area so as to spread the seated user's body weight over a larger surface area and thereby controlling the fluid pressure within the cushion and the restoring force against the seated user's body. By controlling the surface area and the spring compression of the valve, the ball seat O-ring Durometer, as previously described, an optimum pressure of about 30 to about 50 mmHg within the cushion can be achieved.

It will be noted that when support pad 82 is compressed by the weight of a seated user, the empty chambers defined by the support elements or the polyurethane foam itself will expel air. Since the support pad 82 is sealed within the top covering and bottom, air can only escape through valve 85 and opening to allow the cushion to deform and the user to be immersed into the cushion. Hence, seating and positioning characteristics, including immersion, can be controlled by controlling the egress of air out of valve 85. Moreover, when cushion 80 decompresses, air is drawn back into the cushion through valve 85, as will be explained.

In a one embodiment, valve 85 also comprises a labyrinth seal design that dampens dynamic air flow and pressure spikes. In general, valve 85 is constructed having similar components as valve 28, described above. Hence, the elements of valve 85 include the same reference numbers for corresponding elements. However, valve 85 has several features not seen in valve 28, above. In a compressible cushion such as cushion 80, it may be desired to have a valve that not only allows for the controlled expulsion of air and optimal immersion characteristics, it may be desirable to have a valve constructed as to allow ingress of air once load is removed from the cushion, drawing air back into the cushion. Referring to Fig. 5, it can be seen that posterior housing 34 includes vent openings 1 10. There is a substantially circular diaphragm seal 1 12 having a central hole 1 14 positioned so as to cover the vent openings and secured in place in the posterior housing with a seal retainer 1 16 that also has a central opening 1 18 . Diaphragm seal 1 12 generally is made from a flexible material, such as thin rubber or the like.

When load is removed from the cushion and the resilient support elements return to their decompressed state, ambient air is drawn into the vent openings 1 10 and follows pathway A2 through bore 38 into the cushion. It will be noted that in the illustrated embodiment, there are a pair of studs 120 and 122, which may be of different heights, as shown, extending from the posterior side of first labyrinth ring 42. There are several pairs of these studs positioned equidistance apart around the posterior surface of the first labyrinth ring. These studs keep diaphragm seal 1 12 properly positioned and keep it from folding or otherwise distorting. Ordinarily, diaphragm seal 1 12 is biased against the anterior surface of posterior housing 34 by fluid pressure within the valve to form a tight seal to keep air from leaking from the vent holes.

Alternative embodiments of the vent hole arrangements and sealing enhancements of the anterior face of posterior housing 34 are shown if Figs. 6-8. As seen in Fig. 6, the anterior face 124 of posterior housing 34 has a plurality of raised radial ribs 126 and series of concentric, circumferential raised rings 128. The ribs and rings have smooth, flat surfaces. The raised rings and ribs define a plurality of depressions 130. There are a series of vent holes 132 equally spaced around the anterior face, with each vent hole being formed through a depression 130. The diaphragm seal is biased against the flat surfaces of the ribs and rings to effectively seal holes 132. The number of ribs, rings and holes may vary. Because there is less contact surface, less internal pressure is required to maintain an airtight seal.

Fig. 7 illustrates another embodiment of an anterior face 134 of posterior housing 34. As seen, the surface of face 134 is smooth, providing a seat for a diaphragm seal. A series of vent holes 136 are positioned equidistant around the face and are formed with a counter bore 138 to enhance the sealing characteristics. The counter bore assures a good sealing edge around the vent hole and reduces imperfections that could result in a poor seal.

Fig. 8 shows yet another embodiment of an anterior face 140 of a posterior housing. In this aspect, there are a series of raised lugs 142, having flat top surfaces. There is a series of vent holes 144 equidistant around the anterior surface. Each vent hole 144 is surrounded by a raised collar 146, also having a flat surface. The height of lugs 142 and collars 146 is the same. The surfaces of lugs 142 and collars 146 provide diaphragm seal seats that reduce the sealing area and allow the raised collars 146 to provide an airtight seal.

It will be appreciated that the fluid flow characteristics of the illustrated valves can be varied by the use of different springs, different lengths of springs or a different labyrinth orifice and constriction sizes. The fluid flow characteristics also can be varied by the hardness of the ball seat O-ring material. The operative elements of the valve can be made from plastic material and still have sealing characteristics heretofore seen only in metal valves. The valve can be used in a cushion that provides optimal seating characteristics without manipulation. The user rests on the cushion and the self-adjusting valve adjusts so that the cushion has optimum immersion and restoring force characteristics.