Patent Publication Number: US-6209160-B1

Title: Inflation assemblies

Description:
Inflated mattresses (and similar support members for supporting limb portions of a body) are often provided in hospitals. A particular situation where an inflatable mattress is of value is for the easing of bed sores. Such mattresses generally require a bulky pump (possible powered from the electrical mains) and there may be associated control equipment to adjust the pressure within the whole or a part of the mattress due to changing circumstances. Such overall assemblies necessarily are not readily transportable and this limits the potential use of such assemblies in the home when a patient is discharged from hospital but may still benefit from the use of an inflated mattress or the like. 
     According to the present invention there is provided an inflation assembly comprising an inflatable support member for supporting the body or a limb portion of a person, the support member having an inflation inlet provided with a one way inlet valve, together with a container for housing the support member in its deflated state, the container comprising two sleeves each open at one end and closed at the other end and nesting within one another to define a pump having a one way inflation valve in one end adopted for connection to said inflation inlet, the inflation valve also incorporating a pressure limiting relief member for ensuring that the support member cannot be inflated by the pump to greater than a predetermined pressure. 
     Such an assembly is readily transportable when the support member is in its deflated state and rolled up and stored within the housing. It will then occupy a relatively small space and will be lightweight (it is envisaged that the housing will be constructed from robust but lightweight cardboard material). The housing is ideally of cylindrical form and of circular cross-section but it would be possible, for example, to make the housing with a square cross-section or some other desired shape. 
     Ideally the pressure relief valve incorporates an outlet passageway from the pump with a valve body within said outlet passageway and releasably biased towards the interior of the pump into a closing position on a valve seat. The one way inflation valve can advantageously incorporate first and second flexible membranes which act respectively to close off a first opening from the exterior to the interior of the pump and a second opening from the pump interior to the inflation valve outlet, depending upon whether there are positive or negative pressure conditions respectively within the pump. In this arrangement it is preferred that said first flexible membrane carries peripheral ears which will be pressed down by the inner sleeve when the two sleeves are moved fully together to deflect that membrane off the first opening to enable excess pressure within the pump to be relieved. 
     In the preferred arrangement the connection of the inflation valve to the inflation inlet is effective to open the inlet valve. It may be desirable to provide a separate connection member for linking the inflation valve to the inflation inlet. 
     It is particularly advantageous to provide a releasable carrying cord which is connected between the two ends of the container, the length of the cord being such as to limit the degree of allowable extension of the pump to a desired extent. The cord then ensures that the two parts of the housing cannot become detached whilst the housing is being used as a pump, which could cause damage to the housing. The cord also provides a very convenient carrying member which additionally acts to hold the two parts of the housing together during transportation. 
     A pressure relief cap can be provided for insertion into the inlet valve to open the inlet valve to allow deflation of the support member. After deflation the support member can be rolled up and stored away again within the housing. 
    
    
     The invention may be performed in various ways and a preferred embodiment will now be described, by way of example, with reference to the accompanying drawings, in which: 
     FIG. 1 is a perspective view of parts of a inflation assembly of the invention; 
     FIG. 2 illustrates an inflatable support member and of the assembly of FIG. 1 which is being unrolled; 
     FIG. 3 shows how the support member can be inflated by a pump; 
     FIG. 4 is an exploded view illustrating various parts of the pump valves; 
     FIG. 5 is a cross section through the operating end of the inflation pump of FIG. 4; 
     FIG. 6 is an exploded view of the end cap, retention cap and a membrane forming part of the assembly shown in FIG. 4; and 
     FIG. 7 shows a pressure release cap. 
    
    
     The assembly illustrated in the drawings comprises a pair of cylindrical sleeves  1  and  2  (FIG. 3) within which can be housed a deflated and rolled up inflation mattress  3  (FIG.  1 ). When the mattress is removed from the sleeve  2  it can be laid on a bed, held in position by locating straps  4  and unrolled into a flat state. The mattress incorporates an inlet valve  5  to which the pump  6  shown in FIG. 3 can be connected. 
     The pump comprises the sleeves  1  and  2 . The sleeve  2  is closed at the one end  7 . The closed end  8  of the sleeve  1  incorporates an inflation valve assembly as illustrated in detail in FIGS. 4,  5  and  6 . An end cap  9  is mounted into the closed end of the sleeve  1 . A retention cap  10  holds in place two membranes  11  and  12 . The membrane  11  sits over inlet holes in the lower face  13  of the cap  9 . The inner membrane  12  locates over outlet holes  15  in the retention cap  10 . The end cap  9  has a central projection  16  which can be connected to the inlet valve  5  of the inflatable mattress  3 , either directly or via a separate connection member. 
     When the pump is operated, by reciprocating the sleeves  1  and  2  with respect to one another, air is drawn into the expanding space within the two sleeves, as the pump is extended, by entering through the holes  22  (FIGS. 5 and 6) in the base  13  of the end cap  9  as the membrane  11  lifts away. When the sleeves  1  and  2  are pushed together the membrane  11  is pressed down by air pressure to close off the openings  22  in the base  13  of the end cap  9 , but air is able to pass through the holes  15  in the retention cap  10  to push away the membrane  12  and thus allow air to pass through the projection  16  and the attached inflation valve  5  of the mattress. 
     When a desired inflation pressure is reached a pressure limiting relief member  17  operates to prevent further inflation of the mattress. This relief member  17  is shown in detail in enlarged view in FIG.  4 . The relief member has a valve body  18  pressed against a valve seal  19  by a spring  20 . However when the air pressure within the pump  6  reaches a predetermined level the valve body  18  is able to move away from the valve seal  19  by compressing the spring  20  so that the excess pressure is relieved through an outlet passageway  21 . 
     In order for the air to escape through the relief member  17 , the assembly has been designed so that the membrane  12  can lift off the inlet to the member  17 . Although the membrane  12  has a small central hole  23  (FIG. 5) formed in it, the pressure either side of the membrane  12  may be equalised (between that in the centre of the end cap  9  and within the inner sleeve  2 ) so that there will be no tendency for the membrane  12  to lift. To avoid this the membrane  11  is formed with ears  24 . As can be seen from FIG. 5 these ears will be pressed down when the sleeve  2  is pushed fully into the sleeve  1  (which will tend to be the final condition when the pump is operated). The ears  24  then cause the membrane  11  to lift so that the pressurised air within the sleeve  2  can escape through the holes  22  thus enabling the membrane  12  to lift from the member  17  towards the base of the retention cap  10  so that excess pressure within the mattress can escape through the projection  16  and out through the pressure relief member  17 . 
     When it is desired to deflate the mattress for storage a pressure release cap  25  (FIG. 7) can be inserted into the inlet valve  5 . The semi-circular neck  26  of the release cap  25  causes the valve  5  to open so that the air can escape. The mattress can then be rolled up after deflation and reinserted into the container provided by the sleeves  1  and  2 . 
     A cord  27  (FIG.  3 ), releasable at one end, can be connected between the ends of the sleeve  1 ,  2  to limit the extension of the pump so that the sleeves do not become detached during the inflation process. 
     In the preferred design the mattress  3  will be formed from a breathable thermoplastic film in the form of a blown film extruded from thermoplastic polyester urethane elastomer which has been produced by coextrusion with a polyethylene carrier film. The elastomer film, when removed from the carrier, provides a film which has been found to allow transmission of water vapour at a rate sufficient to prevent sweating, but which is substantially impermeable to air. Thus the inflated mattress can sustain its inflated state for long periods which means that it is not normally necessary to re-inflate or top up the mattress in use. An example of a suitable material is a thermoplastic polyurethane elastomer film known as Platilon (Registered Trade Mark) U01, manufactured and marketed by Deutsche Atochem Werke in Germany. 
     The invention is not limited to mattresses but may comprise other inflation support members which may be used for supporting limb portions of a person. These are particularly valuable for use with patients suffering from burns.