Abstract:
The valve assembly has inlet and outlet members with valve elements disposed between the two members. The valve is a resilient membrane having one or more through holes. When there is no pressure differential across the valve, the hole walls in the membrane collapse inwards closing off the valve against liquid flow. At or above a threshold pressure differential across the valve, the membrane is stretched which opens up the hole or holes to allow the passage of liquid.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to valve assemblies for liquid transfer. 
     SUMMARY OF THE INVENTION 
     In accordance with the invention there is provided a valve assembly for liquid transfer, comprising a liquid inlet, a liquid outlet and a valve member disposed between the inlet and outlet; the valve member comprising a resilient membrane separating between the inlet and the outlet, the membrane having one or more holes; in a state where there is no pressure difference between the membrane&#39;s two sides, the walls of the one or more holes are collapsed and no liquid can pass therethrough, and in a certain threshold level, the stretching of the membrane causes opening of the one or more holes to allow liquid to pass from one side of the membrane to the other. 
     In accordance with an embodiment of the invention, the valve is of the one-way type allowing fluid transfer only in one direction. 
     In accordance with another embodiment of the invention, the valve assembly comprises an auxiliary member whereby the membrane can be stretched manually to bring to opening of the one or more holes. 
     The pressure threshold is determined by the thickness and surface area of the resilient member and the size of said one or more holes. 
     By still another embodiment of the invention, the valve assembly comprises a piercing member for piercing the membrane so as to create at least one hole therein, the at least one hole being of the kind defined above. 
     By another aspect of the present invention there is provided a fluid valve assembly consisting of a first valve assembly and a second valve assembly, each of the first and second valve assemblies being independently selected from the group consisting of a valve assembly according to any one of the proceeding claims, wherein a liquid outlet of said second valve assembly is in flow communication with a liquid inlet of said first valve assembly. 
     The invention will now be illustrated in the following non-limiting specific embodiments with particular reference to the annexed drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 shows a schematic representation, in longitudinal cross-section, through a valve assembly in accordance with the invention; 
     FIG. 2 is an enlargement of the circled area in FIG. 1; 
     FIG. 3 shows the valve assembly of FIG. 1 under the application of pressure; 
     FIG. 4 is an enlargement of the circled area in FIG. 3; 
     FIG. 5 is a longitudinal cross-section of a valve assembly in accordance with an embodiment of the invention in which fluid can be transferred in both directions; 
     FIG. 6 is a longitudinal cross-section through a valve in accordance with another embodiment of the invention in which fluid can be transferred only in one direction; 
     FIG. 7 is a longitudinal cross-section through a valve in accordance with another embodiment of the invention, comprising means which allow a manual distortion of the membrane to allow stretching and opening of the holes; 
     FIG. 8 is a longitudinal cross-section through a valve assembly of FIG. 7 after application of the manual force; 
     FIG. 9 is a longitudinal cross-section through a valve assembly in accordance with another embodiment of the invention comprising a piercing membrane; and 
     FIG. 10 is a longitudinal cross-section through a valve assembly in accordance with still another embodiment of the present invention constituting a two-way valve. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Reference is first being made to FIGS. 1-4 giving a schematic representation of a valve assembly in accordance with the invention. The valve assembly  12  comprises a body  14  having a liquid inlet  16  and liquid outlet  18 . (The use of the terms “outlet” and “inlet” in connection with this embodiment is in fact only for convenience as can be appreciated. The valve here is symmetrical and the roles of inlet and outlet can be reversed). Disposed between inlet  16  and outlet  18  and separating the two is a resilient membrane  20 , made for example of silicone rubber. As can be seen in FIG. 2, there is a hole  22  within membrane  20  which is in a position where there is a hole  22  within membrane  20  which is in a position where there is no pressure difference between the two sides of the membrane, the walls thereof are collapsed and the hole is totally closed. 
     When liquid pressure is applied through inlet  16  (represented schematically by the arrow in FIG.  3 ), the membrane  20  deforms and stretches and consequently the opening expands, forming an open hole allowing fluid flow, as can be seen in FIG.  4 . 
     Reference is now being made to FIG. 5 showing a valve assembly  30  in accordance with an embodiment of the invention. The valve assembly comprises housing  32  consisting of two members  34  and  36  engaged with one another. Member  34  defines a fluid inlet  38  and member  36  defines a fluid outlet  40 , which is in this case is a luer-type connector. Membrane  42  is disposed between the inlet and the outlet and held in place by juxtaposed portions of members  34  and  36 . 
     Membrane  42  has a hole which, in the rest position shown in FIG. 5 is closed. When liquid pressure is applied the membrane is deformed (represented by the dotted lines), hole  44  opens allowing fluid flow. Similarly as in the case of the valve assembly of FIG. 1-4, liquid can in principle flow in either direction, depending on the direction of applied fluid (here again, components  38  and  40  are defined as “inlet” and “outlet”, respectively, for the sake of convenience, although the flow direction from inlet  38  to outlet  40  is the preferred direction). 
     Reference is now being made to FIG. 6 showing the valve assembly  50  in accordance with another embodiment of the invention in which liquid flow is permitted only in one direction. The valve assembly  50  comprises a housing  52  consisting of a first member  54  and a second member  56  defining respective inlet  58  and outlet  60 , the latter being a luer-type connector. Disposed within casing  52 , and held between juxtaposed portions of members  54  and  56 , is a resilient membrane  62 . As can be seen, member  54  has a wall portion  64  which lies parallel to the membrane  62  and consequently the membrane can be deformed only in the opposite direction to wall portion  64  (towards outlet  60 ). When liquid pressure applied from inlet  58  (represented by the arrow) exceeds a certain threshold, the membrane deforms (the deformed member being represented by a dotted line) and a pre-existing hole in the membrane  66  which opens up, allows then fluid flow between inlet  58  and outlet  60 . 
     Reference is now being made to FIGS. 7 and 8 which show a valve assembly  70  in accordance with another embodiment. The difference between this embodiment and the embodiment shown in FIG. 6 resides in first member  74  and all other members, which are given the same reference numerals as in FIG. 6, perform in fact the same function. Member  74  has a central portion  80  defining an inlet  82  and an annular bulge  84  which lies proximal to membrane  62 . Central portion  80  is linked to the periphery  86  of member  74  by means of an intermediary flexible shoulder portion  88  which allows relative axial movement between central portion  82  and the periphery  86 . 
     When the central portion is moved versus the periphery so that it presses upon membrane  62 , as can be seen in FIG. 8, the membrane deforms and hole  66  opens and permits liquid flow, the assembly of this embodiment operates essentially in the same manner as that of FIG. 6, i.e. it permits only unidirectional liquid flow. 
     Reference is now being made to FIG. 9 which shows a valve assembly  90  in accordance with another embodiment of the invention. This embodiment is a modification of that shown in FIG.  5  and all like elements were given the same reference numerals. The difference between the two embodiments lies in that assembly  90  has a piercing member  92  and in that shoulders  94  in this embodiment have some flexibility. Consequently, the central portion  96  of member  34  can be pressed slightly towards membrane  42  and the piercing member  92  will then pierce a hole in that membrane. The hole will be sealed at rest and will open when pressure is applied between the two sides of the membrane. 
     As will be appreciated, piercing member  92  can have a lumen allowing liquid flow therethrough. Alternatively, liquid can be permitted to flow through the space  98  surrounding the piercing member. 
     Attention is now directed to FIG. 10 of the drawings showing a two-way valve generally designated  100 . The two-way valve is constructed of two valves  102  and  104 , which in the specific embodiment are similar to the valve illustrated in FIG. 6 as hereinabove described. 
     The first valve  102  is a one-way valve, permitting flow only in the direction of the arrow  106  while the second valve  104  is a one-way valve permitting flow only in the direction of arrow  108 . A fluid outlet  110  of the second valve  104  is attached to a fluid inlet tube  112  of the first valve  102 , the inlet tube  112  having a free end  114  while valve  104  comprises a fluid inlet  115 . 
     The arrangement is such that the two-way valve  100  has three operative positions. In a first position, fluid is admitted through both the free end  114  and the inlet  116 , and as explained in connection with the embodiment of FIG. 6 above, when the liquid pressure exceeds a certain threshold, the membrane  118  of the first valve  102  deforms allowing fluid flow through a pre-existing hole in the membrane (not seen) and via outlet  106 . 
     In a second operative position, fluid is admitted only through the free end  114  with membrane  120  of the second valve  104  serving as a one-way valve, whereby fluid flow is only through the outlet  106  of the first valve member  102 . 
     The third operative position occurs when fluid is admitted only through the fluid inlet  116  of the second valve  104 , whereby fluid flows only through the free end  114 , owing to essentially high pressure which is required for deforming the membrane  118 . 
     However, a specific application of the valve assembly of FIG. 10 is for example, in a patient feed system, wherein a feed tube is connected to the outlet of the first valve  102  leading to the patient. A first liquid nutrition container ( 151 ) is connected to the inlet  116  of the second valve assembly  104  a second liquid container  152  is connected to the inlet  114  via a pump (not shown as known per se). In a first mode of operation the pump pumps liquid from the second liquid container into the inlet tube  112 , whereby the liquid is forced through the first valve assembly  102  but can not pass through the second valve assembly  104 . In a second mode of operation the pump works in a reversed direction, whereby a measured amount of liquid from the first liquid container is sucked into the line of leading to the second liquid container and than again the pump reverses its operation whereby said measured amount of liquid is pressurized through the first valve assembly  102  as above explained. In this way liquid from either of two containers, e.g., a nutritive agent and water or rinsing agent may be alternately supplied to a patient. 
     Also seen in FIG. 10, are projections  122  and an annular projection  126  projection from the rear wall  124  of the valve assemblies, for ensuring that the membranes  118  and  120  do not adhere to the rear wall  124  of the valve assemblies  102  and  104 , respectively, and that the resilient membranes do not deform in a reverse direction (i.e., in a direction towards the valve&#39;s inlets) for ensuring fluid flow in one direction only.