CUSHION AND SELF-ADJUSTING VALVE

Abstract

A cushion with a support pad comprising a plurality of compressible suspension elements with a cover top and bottom joined together to form an impervious barrier, 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. When the user is removed from the cushion, the valve allows ingress of air into the cushion. In one aspect, the valve comprises an expansion valve controls air flow out of and into the cushion. In one aspect, the valve comprises a labyrinth seal that dampens air flow and pressure spikes. The valve comprises a pressure responsive compression spring that controls the expulsion of air from the cushion and, consequently, adjusting the immersion depth of the seated user.

Description

BACKGROUND OF THE INVENTION

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. Pat. No. 4,541,136 shows a cellular cushion currently manufactured and sold by assignee, ROHO, Inc. of Belleville, Illinois, for use on wheelchairs.

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. Pat. No. 5,163,196 and U.S. Pat. No. 5,502,855 disclose other zoned cellular cushions having isolated inflation zones.

Two types of valves used to maintain air volume in the inflation zones are shown in U.S. Pat. No. 6,687,936 and U.S. Pat. No. 6,687,936. 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.

Each valve, in general, includes a casing having an internal bore and a plurality of openings along the length of the casing that open into the bore. The openings are connected to the individual inflation zones via tubing or the like to place the bore of the casing in communication with the inflation zones. The valve also includes a movable slide seated snugly within the casing bore. The slide can be manipulated to align the discrete air chambers with the casing openings so as to functionally align the slide openings with the casing openings to allow the inflation zones to communicate and the air to flow to and from the various inflation zones through the valve slide bore. The cushion is inflated and the user positioned on the cushion. Air is released from a fill valve until the user reaches optimum immersion. The slide is manipulated to move the slide openings and the casing openings out of alignment, thereby sealing off the inflation zones and maintaining the individual inflation zones at optimum internal pressure.

Zoned cellular cushions with slide valves have become an industry standard and work exceptionally well for there intended purposes. As will be understood, users of these cushions and valves, or their caregivers, require some training and practice at setting the desired immersion dept and seating position. 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 even a mattress or mattress overlay, that 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, 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 or the like.

SUMMARY OF THE INVENTION

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, a cushion with a support surface comprises a support pad with a plurality of compressible suspension elements that when the user gets off of the cushion, the support pad returns the cushion to the original cushion height and the valve allows ingress of air into the cushion.

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 cushion comprises a cover bottom under the support surface; the preferred embodiment of the cover bottom is a polyurethane film.

In one aspect, the cushion comprises a cover top over the support surface; the preferred embodiment of the cover top is a polyurethane film.

In an alternative embodiment, the cover top over the support surface can have fabric bonded to the polyurethane film, providing a cover top over the support surface that is easily cleaned by wiping down with a mild cleaning solution.

In one aspect each suspension element has a displaceable, load-bearing surface, a first end wall, a second end wall, and an optional bottom wall. The load bearing surface, end walls and bottom wall, if present, define an inner chamber. The material thickness of the load-bearing surface is greater than the material thickness of the end walls so that the end walls can distend outwardly when force is applied to said load-bearing surface. Optionally, a top wall can include a vent opening formed therein of a predetermined size that allows controlled release of air from each chamber when force is applied to the load bearing surface to control collapsing of the cell.

In one aspect, the support surface of the cushion is displaceable such that, when deformed, the suspension elements exert a restoring force that is generally constant irrespective of the extent of the deflection. The cushion applies distributed supporting pressure against an irregularly contoured body area, such as the ischium, supported on the cushion.

In one aspect of the cushion the array of suspension elements is arranged in a pattern wherein the longitudinal axis of each suspension element is positioned at a right angle relationship to the longitudinal axis of the adjacent suspension elements. The right angle axis position of the suspension elements improves stability imparted to the user.

In one aspect of the cushion the load-bearing surface has a generally arch-like cross-sectional configuration to facilitate a controlled buckling function. In other aspects of the invention the load-bearing surface has a substantially elliptical cross-sectional configuration or a substantially rectangular cross-sectional configuration.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded view of one aspect of the cushion;

FIG. 2 is a front perspective view of the support surface;

FIG. 3 is a front plan view of a section of the support surface illustrating the placement of the self-adjusting valve;

FIG. 4 is a side elevational view of the self-adjusting valve;

FIG. 5 is a bottom plan view of a support surface;

FIG. 6 is a perspective view of the cover top;

FIG. 7 is a bottom plan view of the assembled cushion;

FIG. 8 is a perspective view of an optional top air pad;

FIG. 9 is a cross sectional view of one embodiment of a self-adjusting valve, wherein the valve comprises an axial labyrinth seal design;

FIG. 10 is a cross-sectional view of another embodiment of a self-adjusting valve, wherein the valve comprises a radial labyrinth seal design; and

FIG. 11 is a cross-sectional view of another embodiment of a self-adjusting valve, wherein the valve comprises an expansion valve design.

DETAILED DESCRIPTION

One aspect of the 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 or any other such support surfaces for supporting the anatomy of a user.

Cushion 20 comprises a support surface 22, a cover bottom 24 a cover top 26 and a valve 28. Referring to FIG. 2, support surface 22 comprises a resilient pad having anterior section 30 and a posterior section 32. Generally, the anterior and posterior sections of the support surface are formed from a compressible, resilient material such as polyurethane foam. In general, posterior section 32 may be formed from stiffer foam than anterior section 30 such that posterior section 32 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. It will be understood that support surface 22 can be a single or unitary piece as well.

The anterior wall 33 of the support surface defines a cavity 34 for housing valve 28, as will be described below. Both anterior section 30 and posterior section 32 comprise a plurality of cells or suspension elements 35 arranged in lateral and transverse rows across the expanse of the sections, as seen in FIG. 5. It will be understood that the support surface, whether a single piece or comprising an anterior or posterior section is made, and functions, in accordance with the principles disclosed in the assignee's U.S. Pat. No. 7,424,761 and 7,681,264, both of which are incorporated herein by reference.

In one aspect, each suspension element 35 has a displaceable, load-bearing surface 36, a first end wall 38 and a second end wall 40. The load bearing surface, end walls define an inner chamber 42. Chambers 42 can be empty or filled, for example, with foam or other material to change the support characteristics of the cushion or the air egress and ingress characteristics of the cushion. Moreover, chamber 42 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 36 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.

The load bearing surfaces 36 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 pad 22 applies a generally uniform supporting pressure against an irregularly contoured body supported on the cushion. In one aspect of the invention the array of suspension elements is arranged in a pattern wherein the longitudinal axis of each suspension element is positioned at a right angle relationship to the longitudinal axis of the adjacent suspension elements. The right angle axis position of the suspension elements improves stability imparted to the user.

In one aspect of the invention the load-bearing surface 36 has a generally arch-like cross-sectional configuration to facilitate a controlled buckling function. In other aspects of the invention the load-bearing surface can have a substantially elliptical cross-sectional configuration or a substantially rectangular cross-sectional configuration. In another aspect of the support surface where the arch-like or elliptical suspension elements 35 have the displaceable load-bearing surface 36 down, a web-like membrane of compressible resilient material 37 between suspension elements 35 prevents the suspension elements from splaying at the user interface of the support surface under the seated user.

In the illustrated embodiment there is cover top 26 that covers the top surface of support pad 22 as well as cavity 34 and provides openings 43 for valve 28 in fluid communication with the atmosphere, as seen in FIG. 6. Cover top 26 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. In an alternative embodiment the cover top can have a plurality of small holes therein, with one hole positioned over each cell chamber 42 or select cell chambers and a top air pad 44 with opening 43, as seen in FIG. 8, having individual air pads 46 of vacuum formed plastic can be positioned over the support surface. One aspect of the top air pad 44 includes the array of individual air cell pads 46 in fluid communication with the support surface to reduce friction and shear at the user interface of the support surface under the seated user.

A cover bottom 24, as seen in FIG. 7, having 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 24 duplicates the configuration of the suspension elements 35, as at 47, which seats the suspension elements. This arrangement reduces the volume of the cushion and, therefore, reduces the amount of air within cushion 20, 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 26 and cover bottom 24 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 22 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 20 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, as will be explained below, an optimum pressure of about 40 to about 50 mmHg within the cushion can be achieved.

It will be noted that when support pad 22 is compressed by the weight of a seated user, the inner chambers 42 and the polyurethane foam itself will expel air. Since the support pad 22 is sealed within the top covering and bottom, air can only escape through valve 28 and opening 43 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 28, as will now be explained.

Valve 28 is positioned in cavity 34 and is in fluid communication with the interior of the cushion in any acceptable manner. For example, valve 28 can be in fluid communication with a conduit 48 that extends into cavity 34. Alternative, valve 28 can be in fluid communication with the interior of the cushion though a hole in the cushion top covering, bottom covering or any other structure so as to be in fluid communication with the interior of the cushion. A separate conduit is not required.

In a preferred embodiment, valve 28 comprises a labyrinth seal design that dampens dynamic air flow and pressure spikes. In general, aft pressure from cushion 20 with a seated user causes the valve ball to close 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 get optimal seating characteristics.

FIGS. 9 through 11 are cross-sectional schematics of various configurations of valve 28, referred to as valves 28A, 28B and 28C in the respective drawings. Referring to FIG. 9, valve 28A has a casing 49 with an elongated extension 50. Casing 49 can be of any configuration, however, a cylindrical, circular or disk-like configuration works well, as seen in FIGS. 3 and 4. Extension 50 can be tubular with an internal bore 52. Circumferential barb 54 functions to secure the extension within conduit 48. Conduit 48 is in fluid communication with the interior of the cushion and, hence, bore 52 and valve 28 are in fluid communication with the interior of the cushion.

Bore 52 also is in fluid communication with a labyrinth inside the valve casing. For example, air flow from the interior of the cushion follows a path shown by arrows A1. At stricture 57 the fluid flow is constricted; there is a significant pressure drop as the fluid flow expands into chamber 58; again there is constriction at stricture 59 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 contacts valve ball 66. Valve ball 66 is biased in a closed position against valve seat 67 by valve spring 68. It will be understood that as long as valve ball 66 is biased against valve seat 67, no air will escape through the valve. However, when a predetermined fluid pressure resulting from the user sitting on cushion 20 is applied against the valve ball by the air flow, valve ball 66 is urged away from valve seat 67 and air will escape from valve 28 through exhaust port 69.

Valve spring 68 has 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 (½) to (1) inch from the surface on which the cushion is position, for example, a wheelchair seat. Also, valve spring 68 is selected so that the fluid pressure within the cushionis about 40 to about 50 mm Hg, resulting in a uniform restoring force against the seated user's body.

Since valve 28 comprises the labyrinth configuration, the step down in pressure is such that the force required to open the valve 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 pressure within the cushion the fluid pressure within the cushion and the restoring force against the seated user's body allows the valve spring 68 to overcome the fluid pressure and close 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.

Valve 28 includes an inflation valve, indicated generally by reference number 70 which, in a preferred aspect, comprises air ports 72 in fluid communication with the atmosphere. Inflation valve 70 includes a flap 74 comprising a somewhat flexible but durable material such as silicon, Teflon® or the like, which seals ports 72 under pressure from within valve 28. However, when the user is off the cushion, the atmospheric pressure, which then is generally greater outside the cushion than within, causes air to flow through ports 72 and into the cushion following a path shown by arrows A2, aided by mechanical drawing in of air by the foam within the cushion as a changes from a compressed to non-compressed state.

Valve 28B is illustrated in FIG. 10. Valve 28B is constructed very similarly to valve 28A. Valve 28B includes a casing 49 with an extension 50 having an internal bore 52 and circumferential external barb 54. Bore 52 is in fluid communication with the interior of the cushion and a labyrinth inside the valve casing. Air flow from the interior of the cushion follows a path shown by arrows A1. At stricture 57 the fluid flow is constricted with a pressure drop at the fluid flow expands into chamber 58; there is constriction at stricture 59 and a pressure drop at chamber 60. There is a third constriction of flow at stricture 62 and a pressure drop at chamber 64. Valve 28B includes a valve ball 66, valve seat 67, valve spring 68 and exhaust port 69 that that function in the same manner set out above in regards to valve 28A.

Valve 28B also includes an inflation valve, indicated generally by reference number 70 which comprises air ports 72 in fluid communication with the atmosphere. Inflation valve 70 includes a flap 74, which seals ports 72 under pressure from within valve 28. Air flows in through ports 72 and into the cushion, following a path shown by arrows A2, as explained above.

Valve 28C is illustrated in FIG. 11. Valve 28C is constructed very similarly to valves 28A and B. Valve 28C includes a casing 49 with an extension 50 having an internal bore 52 and external barbs 54. Bore 52 is in fluid communication with the interior of the cushion and the expansion chambers inside the valve casing. Air flow from the interior of the cushion follows a path shown by arrows A1. At orifice 57 the fluid flow is constricted and a pressure drop as the fluid flow expands into chamber 76; there is constriction at orifice 77 and a pressure drop at chamber 78. Valve 28C includes a valve ball 66, valve seat 67 and valve spring 68 and exhaust port 69 that function in the same manner set out above in regards to valve 28A.

Valve 28C also includes an inflation valve, indicated generally by reference number 70 comprises air ports 72 in fluid communication with the atmosphere. Inflation valve 70 includes a flap 74 which seals ports 72 under pressure from within valve 28C. Air flows in through ports 72 and into the cushion following a path shown by arrows A2, as explained above.

It will be understood that the valves described can be employed in cushions or mattresses of designs different from the cushion illustrated herein. The valve can be constructed so as to accommodate users of different sizes. The fluid flow characteristics can be varied by the use of different springs or a different labyrinth seal clearances or orifices. 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.

Claims

1-18. (canceled)

19. A cushion comprising: a support surface comprising a plurality of compressible suspension elements, anda valve in fluid communication with the plurality of compressible suspension elements having internal labyrinth structures that provide a controlled expulsion of air from the cushion to dampen air flow until a user positioned on the cushion is optimally immersed in the cushion and control pressure spikes caused by movement on the cushion.

20. The cushion of claim 19 wherein the valve comprises an expansion valve.

21. The cushion of claim 19 wherein the valve comprises a pressure responsive compression spring, said compression spring having a predetermined compression force that controls the expulsion of air from the cushion corresponding to a desired immersion depth of the user.

22. The cushion of claim 19 further comprising a cover having a top and a bottom, the bottom configured complementary to the suspension elements to control splaying of the suspension elements under load.

23. The cushion of claim 22 wherein the cover top comprises vacuum formed polyurethane.

24. The cushion of claim 19 wherein the support surface comprises a anterior section and a posterior section comprising polyurethane foam, said posterior section having a greater restoring that the anterior section.

25. The cushion of claim 24 wherein said anterior section of the support surface has a cavity formed therein to house the valve.

26. The cushion of claim 19 wherein the compressible suspension elements are inflatable air cells.

27. The cushion of claim 19 wherein the valve further comprises: a valve seat,a valve ball positioned adjacent the valve seat, anda bias spring for biasing the valve ball against the valve seat to close the valve.

28. The cushion and valve of claim 19 wherein the labyrinth structures comprise a labyrinth seal that dampens air flow and pressure spikes at the valve ball.

29. The cushion and valve of claim 19 wherein the valve further comprises an inflation valve in fluid communication with the atmosphere to allow expansion of the compressible suspension elements.

30. A valve for a cushion having compressible suspension elements, comprising: a valve ball and pressure responsive compression spring having a predetermined compression force that controls expulsion of air from the cushion corresponding to a desired immersion depth of a user, and a labyrinth structure in fluid communication with the compressible suspension elements and the valve ball that dampens dynamic air flow and pressure spikes against the valve ball.

31. The valve of claim 30 further comprising inflation valve structures that allow an ingress of air into the suspension elements when load is removed from the cushion.