Abstract:
A check valve suitable for use with IV sets and the like provides an upstream filter preventing contamination from affecting the sealing of the check valve membrane. The filter may employ filter media that is integrally bonded to the housing of the filter providing simple and robust construction.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. application 61/748,236 filed on Jan. 2, 2013 and hereby incorporated by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates generally to one-way check valves and, more particularly, to one-way check valves used in medical fluid delivery systems; and, still more particularly, to contaminant screens and particulate isolating features to protect check valve performance in intravenous (IV) administration sets. 
       BACKGROUND OF THE INVENTION 
       [0003]    It is known to provide intravenous (IV) drug and fluid delivery systems that include a primary line connected to a bag of saline or other fluids, and a branch or auxiliary line connectable to supplies of drugs or other treatment fluids. The branch line and main line are connected at a Y-connector. A check valve is provided in the main line to prevent backflow of the secondary fluid into the main fluid bag. When a drug is dispensed, the backflow pressure on the check valve closes the valve to prevent backflow of the drug into the saline or other non-drug bag. When a drug or other fluid is not dispensed from the auxiliary line, saline flows freely through the check valve. 
         [0004]    A known check valve for this purpose is taught by U.S. Pat. No. 4,765,372 hereby incorporated by reference. The valve disclosed therein includes a housing, a biasable diaphragm within the housing and a valve seat carried by the housing against which the diaphragm is urgeable. The housing has a fluid inlet and a fluid outlet. The diaphragm is preferably disposed transverse to a preselected direction of fluid flow through the housing for controlling fluid flow therethrough. The diaphragm can be urged against the seat for preventing fluid from flowing contrary to the preselected direction of flow. The housing engages opposite sides of the diaphragm so that areas of the diaphragm can be moved away from and toward the valve seat without the diaphragm being displaced from its operative position within the valve. 
         [0005]    While valves of the type described have worked successfully, contaminants in the system can interfere with proper operation. If a contaminant particle embeds itself in the diaphragm or seal surface, a proper seal may not be provided. The particle may prop open the diaphragm, in which case a drug dispensed from the secondary path may backflow through the check valve, thereby preventing the patient from receiving the proper drug dosage concentration or timely delivery of the drug. 
         [0006]    Contaminants can be created during the manufacture and assembly of IV sets. Particles from many sources can migrate and be trapped in the IV set, and later be carried by fluids into the check valve. The sources of contaminant particles include and are byproducts of handling, processing and migration of other materials that work their way into the IV set system. For example, it is known to cut tubes and assemble bag spike components to enable attachment to associated devices. Cutting or puncturing the tube can generate tubing debris that can compromise the sealing function if the particles migrate to the check valve. Other particles from the environment also can be trapped in the IV set and be carried to the check valve. 
         [0007]    PCT patent application WO 2010/107597, hereby incorporated by reference and assigned to the assignee of the present invention, describes a check valve having an integrated screen to trap contaminant particles away from a sealing area of the check valve. 
       SUMMARY OF THE INVENTION 
       [0008]    The present invention provides improved methods of integrating upstream filters into check valve assemblies in which the filter medium is attached directly to the check valve housing element that provides the entrance port and/or valve seat. This close integration reduces assembly costs and provides a robust structure which prevents contaminants from interfering with sealing of the check valve. 
         [0009]    Specifically, the invention provides a combination check valve and filter having a housing formed of first and second unitary molded thermoplastic elements joined to provide a cavity therebetween and providing fluid communication between an opposed entrance port formed in the first unitary molded thermoplastic element and an exit port formed in the second unitary molded thermoplastic element. A valve seat is attached to a cavity wall formed by the first unitary molded thermoplastic element and a flexible diaphragm responsive to fluid flow through the cavity is positioned adjacent to the valve seat to seal against the valve seat with fluid flow from the exit port to the entrance port and to unseal away from the valve seat with fluid flow from the entrance port to the exit port. Filter medium disposed in the housing between the entrance port and the valve seat and the filter medium is integrally bonded at its periphery to the first unitary molded thermoplastic element. 
         [0010]    It is thus a feature of at least one embodiment of the invention to substantially reduce the number of parts and hence the cost of producing a combination filter check valve that can reduce check valve failure. 
         [0011]    The entrance port may provide a counter-bore presenting a radial ledge facing away from the cavity and wherein the periphery of the filter medium abuts and is bonded to the ledge. 
         [0012]    It is thus a feature of at least one embodiment of the invention to provide a simple and mechanically robust method of attachment of flexible filter media. It is a further feature of this embodiment to provide for post-assembly insertion of the filter after the housing components are joined. 
         [0013]    The valve seat may extend about an opening of the entrance port into the cavity and, in an alternative embodiment, the periphery of the filter medium may cover the opening and be bonded to a cavity wall within the valve seat. 
         [0014]    It is thus a feature of at least one embodiment of the invention to provide an integrated filter that adapts well to punch and molding assembly techniques or insert molding where the filter media is bonded by embedding its periphery in the molten plastic of the housing. 
         [0015]    The filter medium may abut the flexible diaphragm when the flexible diaphragm seals against the valve seat to support the flexible diaphragm. 
         [0016]    It is thus a feature of at least one embodiment of the invention to provide mechanical support of the flexible diaphragm against high-back pressures particularly important for edge supported diaphragms that rely on a stretching of the diaphragm material for compliance. 
         [0017]    The filter medium may be a woven or nonwoven flexible fabric. 
         [0018]    It is thus a feature of at least one embodiment of the invention to provide a readily assembled filter system that works with a variety of filter medium. 
         [0019]    The filter medium may be bonded by embedding material of the filter within the thermoplastic of the first unitary molded thermoplastic element. 
         [0020]    It is thus a feature of at least one embodiment of the invention to permit an assembly technique with high mechanical strength and short assembly time. 
         [0021]    In some embodiments the filter medium may be a perforated thermoplastic element integrally molded as part of the first unitary molded thermoplastic element. 
         [0022]    It is thus a feature of at least one embodiment of the invention to fully integrate the filter with the housing components to eliminate all assembly steps with respect to the filter. 
         [0023]    The perforated thermoplastic element may provide a grid of a set of crossing rectilinear elements, the elements of each set crossing to abut at regular intersections. 
         [0024]    It is thus a feature of at least one embodiment of the invention to provide a filter architecture well adapted to simple injection mold cavities. 
         [0025]    The entrance port and exit port may be aligned along a central axis and first and second unitary molded thermoplastic elements may provide flanges extending radially from the axis about ends of the entrance port and exit port, the flanges joined at their peripheries to create the cavity. 
         [0026]    It is thus a feature of at least one embodiment of the invention to provide a simple housing structure to permit low-cost manufacture of the combined filter and check valve. 
         [0027]    The flanges may provide axially extending features that capture a periphery of the flexible diaphragm therebetween so that the entire periphery of the flexible diaphragm is held substantially stationary when the flexible diaphragm seals against the valve seat and unseals away from the valve seat. 
         [0028]    It is thus a feature of at least one embodiment of the invention to provide a low backflow check valve using a peripherally supported diaphragm. 
         [0029]    The valve seat may be integrally molded with the first unitary thermoplastic element or in an alternative embodiment the valve seat may be a third unitary molded thermoplastic element positioned between the first and second unitary molded thermoplastic elements retained thereby when the first and second unitary molded thermoplastic elements are joined thereby. In this latter case, the third unitary molded thermoplastic element may provide a central aperture having a first opening surrounded by the valve seat on a first side of the third unitary molded thermoplastic element facing the cavity and having a second opening on a second opposite side of the third unitary molded thermoplastic element. In this latter embodiment, the periphery of the filter medium may abut and be bonded to the second opposite side of the third unitary molded thermoplastic element about the second opening. 
         [0030]    It is thus a feature of at least one embodiment of the invention to provide an additional housing component to form a secondary cavity for holding a filter element allowing increased filtration area without compromise of the valve action (for example by requiring enlargement of the valve seat such as might promote additional leakage). 
         [0031]    The third unitary molded thermoplastic element may provide a filter medium that is a perforated thermoplastic element integrally molded as part of the third unitary molded thermoplastic element. 
         [0032]    It is thus a feature of at least one embodiment of the invention to permit different molding techniques to be used on the housing and the filter medium to provide greater flexibility in creating small aperture filter media. 
         [0033]    Other features and advantages of the invention will become apparent to those skilled in the art upon review of the following detailed description, claims and drawings in which like numerals are used to designate like features. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0034]      FIG. 1  is a fragmentary perspective view of an IV set having a filter/check valve of the present invention therein; 
           [0035]      FIG. 2  is an exploded perspective diagram of a first embodiment of the invention showing upper and lower housing components as may contain a flexible diaphragm providing a check valve function; 
           [0036]      FIG. 3  is a cross-sectional view of the first embodiment of the invention taken along line  3 - 3  with the flexible diaphragm in a sealed position against backflow; 
           [0037]      FIG. 4  is a fragmentary portion of  FIG. 3  with the flexible diaphragm in the open position allowing forward flow; 
           [0038]      FIG. 5  is a figure similar to that of  FIG. 3  showing a second embodiment of the invention; 
           [0039]      FIG. 6  is a figure similar to  FIG. 5  showing a third embodiment of the invention; 
           [0040]      FIGS. 7   a  and  7   b  are figures similar to  FIG. 6  showing a fourth embodiment of the invention with a molded filter and showing a fragmentary detail of that molded filter; and 
           [0041]      FIGS. 8   a ,  8   b  and  9  are figures similar to those of  FIGS. 7   a  and  7   b  showing a fifth embodiment of the invention with a micro-molded filter. 
       
    
    
       [0042]    Before the embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced or being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein are for the purpose of description and should not be regarded as limiting. The use of “including” and “comprising” and variations thereof is meant to encompass the items listed thereafter and equivalents thereof as well as additional items and equivalents thereof. 
       DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0043]    Referring now to  FIG. 1 , an IV set system  10  is shown and includes an IV check valve  12  therein. IV set system  10  includes an IV standard or pole  14  carrying an IV pump  16  thereon for administering fluid flow from a main fluid subsystem  18  and a branch or auxiliary fluid subsystem  20 . IV standard or pole  14  includes first and second arms  22 ,  24  from which main fluid subsystem  18  and auxiliary fluid subsystem  20  are suspended. IV pump  16  receives fluid from main fluid subsystem  18  and branch or auxiliary fluid subsystem  20  via a supply line  26  and controls and dispenses the fluids therefrom to the patient via a patient IV line  28 . 
         [0044]    Main fluid subsystem  18  includes a main fluid source such as a fluid bag  30  which may include or contain saline solution or other fluid to be administered to the patient. Fluid bag  30  is suspended from arm  22  by a tether or strap  32 . An outlet feature  34  from fluid bag  30  is connected to a drip chamber  36 . A fluid line  38  carries flow from drip chamber  36  to a Y-connector  40 . Check valve  12  is disposed in fluid line  38  upstream from Y-connector  40  and enables flow from fluid bag  30  to IV pump  16  while preventing backflow of fluid from an auxiliary fluid subsystem  20  toward fluid bag  30 . 
         [0045]    Branch or auxiliary fluid subsystem  20  includes an auxiliary fluid source such as a fluid bag  39  which may contain drugs or other fluid to be supplied to the patient for treatment. Fluid bag  39  is suspended from arm  24  by a tether or strap  42 . An outlet feature  44  from fluid bag  39  is connected to a drip chamber  46 . An auxiliary fluid line  48  carries flow from drip chamber  46  to Y-connector  40 . A flow regulator  50  can be used in fluid line  48  to control the rate of flow from the fluid bag  39  to IV pump  16 . 
         [0046]    It should be understood that, apart from check valve  12  to be described in further detail hereinafter, the exemplary IV set system  10  components shown and described are merely exemplary in nature, and check valve  12  can be used in other types of IV systems as well as in fluid flow systems of other types, for other purposes. 
         [0047]    Referring now to  FIG. 2 , the check valve  12  may provide for an entrance housing section  60  and an exit housing section  62  each having bores  64  and  66  respectively extending along a common axis  68 . The bores  64  and  66  may receive upper and lower ends of the fluid line  38 , discussed with respect to  FIG. 1 , according to attachment methods well known in the art. 
         [0048]    Opposed ends of the bores  64  and  66  may open through flanges  70  and  72  respectively on the entrance housing section  60  and exit housing section  62 , the flanges  70  and  72  extending radially about the axis  68 . The opposing flanges  70  and  72  may join together at their peripheries  74  to define a liquid-tight cavity  76  being part of a continuous passage from the bore  64  of entrance housing section  60  to the bore  66  of exit housing section  62 . 
         [0049]    Each of the entrance housing section  60  and exit housing section  62  may be unitary molded thermoplastic components, for example, molded with a single injection of thermoplastic into a mold cavity. The thermoplastic material may be any of various synthetic materials such as polyethylene, polypropylene or the like providing medical grade biocompatible materials. 
         [0050]    A circular elastomeric membrane  80  may have an enlarged rim  82  that may be captured in opposed channels  81  extending about the peripheries  74  of the flanges  70  and  72 . When the rim  82  is captured in the channels  81 , a center section of the elastomeric membrane  80  may flex toward the entrance housing section  60  or toward the exit housing section  62  with the flow of fluid through the check valve  12 . A set of peripheral openings  84  may be provided in-between the rim  82  and the center of the elastomeric membrane  80  to permit this flow. Elastomeric membrane  80  is a flexible and resilient material such as a synthetic rubber impervious to fluid. 
         [0051]    Referring now to  FIG. 3 , when fluid flow is backward toward entrance housing section  60 , the elastomeric membrane  80  is pulled against the rim of an annular valve seat  86  surrounding an opening  90  of the bore  64  and extending into the cavity  76 . The annular valve seat  86  is positioned inside of the peripheral openings  84  and thus when the annular valve seat  86  contacts the elastomeric membrane  80  it blocks the only passageway between the bore  64  and cavity  76 , sealing that check valve  12  against flow to essentially block backflow. 
         [0052]    Referring to  FIG. 2 , conversely when fluid flow is forward and downward toward exit housing section  62 , the elastomeric membrane  80  is pulled against radial ribs  92  blocking further distention of the elastomeric membrane  80  but allowing flow through the peripheral openings  84  and channels  96  in the exit housing section  62  through opening  94  leading to the exit bore  66 . 
         [0053]    In the embodiment of  FIGS. 3 and 4 , bore  64  is a counter bore providing an axially radial and upwardly facing ledge  100  formed by a reduction in diameter of the bore  64  as it enters cavity  76  through opening  90 . Filter medium  102 , for example, in the form of a disk having a diameter equal to the diameter of the large portion of the bore  64  may be bonded at its periphery to the ledge  100  to cover the opening  90 . The bonding system may employ ultrasonic welding, heat sealing, gluing or other attachment methods. In one embodiment, the bonding may embed the material of the filter medium  102  within the thermoplastic of the entrance housing section  60 , for example, by insert molding or by partially melting the thermoplastic material of the entrance housing section  60  and/or the filter medium  102 . 
         [0054]    Referring now to  FIG. 5 , in an alternative embodiment, the filter medium  102  may be attached to a lower face of the flanges  70  of the entrance housing section  60  facing the cavity  76  and within the annular valve seat  86 . In particular, the downward opening  90  may open into a radially extending surface  104  within the valve seat  86  to which the periphery of the filter medium  102  is bonded using techniques as described above. In this location, upward back-flow of liquid against the elastomeric membrane  80  presses the center of the elastomeric membrane  80  into the filter medium  102  which supports the elastomeric membrane  80  preventing it from stretching beyond its elastic limit and suffering loss of function when subjected to very high back pressure. In all other respects, the valve  12  may be identical to that described above with respect to  FIGS. 2 and 3 . 
         [0055]    This embodiment is particularly suited for punching the filter medium  102 , for example, from a continuous sheet of filter media integrated into the injection molding process or by insert molding with disks die cut from a sheet of material and insert molding it at the time of molding of entrance housing section  60 . 
         [0056]    Referring now to  FIG. 6 , in yet an alternative embodiment, flange  70  and  72  may be joined to each other by way of a valve seat component  106  having substantially equal diameter to flange  70  and  72  to join at its upper periphery to flange  70  (as depicted) and to join at its lower periphery to flange  72 . Valve seat component  106  provides the annular valve seat  86  about a bore  108  axially aligned and corresponding generally in diameter to opening  90 . The valve seat component  106  further provides a channel  81  to capture rim  82  of the elastomeric membrane  80  described above. 
         [0057]    Importantly, the valve seat component  106  provides an upper countersink surface  110  around the upper edge of opening  89  mirroring and opposed to lower countersink surface  112  about the lower edge of opening  90 . Filter medium  102  may be sandwiched between flange  70  and the upper surface of valve seat component  106  within a secondary cavity  114  formed by the opposed countersink surfaces  110  and  112  to extend across the axis  68  to filter flow between openings  90  and  89 . This embodiment provides a greater filtration area by the effectively large diameter of the cavity  114 . 
         [0058]    As before, the filter medium  102  may be bonded to one or both of the flange  70  and valve seat component  106  by any of the means described above. Alternatively, the filter medium  102  may be simply mechanically clamped between these components. Cavity  114  allows increasing the filtration area without adversely affecting the size of the valve seat  86  or the channels  81  and hence the size of the elastomeric membrane  80 . In all other respects, the valve  12  may be identical to that described above with respect to  FIGS. 2 and 3 . 
         [0059]    Referring now to  FIGS. 7   a  and  7   b , in yet an alternative embodiment, filter medium  102  may be formed by a molded grid  116  having a set of openings  118 , for example, formed at spaces between crossing rectilinear elements  120  and  122  intersecting at right angles with elements  120  axially displaced with respect to rectilinear elements  122 . The molded grid  116  may be integrally formed with entrance housing section  60  as part of the molding process of entrance housing section  60  so that the filter medium  102  is bonded to the entrance housing section  60  and extends across the lower edge of opening  90  to present a lower surface (as pictured) providing the supporting function of the elastomeric membrane  80  described above with respect to  FIG. 5 . 
         [0060]    Referring now to  FIGS. 8   a ,  8   b , and  9  in an alternative embodiment, the filter medium  102  may be molded as a separate component  124 , for example, in the form of a disk incorporating on its lower surface the annular valve seat  86  and fitting within a cylindrical cavity of equal size at the lower edge of opening  90 . By allowing this separate component  124  to be removable, it may be micro-molded to provide extremely small openings  118  in the grid  116  using a different molding process than used for the entrance housing section  60  and exit housing section  62 . The filter medium  102 , when installed, may again present a lower surface as depicted providing the supporting function of the elastomeric membrane  80  described above with respect to  FIGS. 5 and 7 . Filter medium  102  may be bonded or glued to the entrance housing section  60  or may be held by compression by the elastomeric membrane  80  at a point of contact with a rib  92 . 
         [0061]    Screen openings for filter medium  102  between 15 microns and 130 microns may be provided by various molding techniques. 
         [0062]    Certain terminology is used herein for purposes of reference only, and thus is not intended to be limiting. For example, terms such as “upper”, “lower”, “above”, and “below” refer to directions in the drawings to which reference is made. Terms such as “front”, “back”, “rear”, “bottom” and “side”, describe the orientation of portions of the component within a consistent but arbitrary frame of reference which is made clear by reference to the text and the associated drawings describing the component under discussion. Such terminology may include the words specifically mentioned above, derivatives thereof, and words of similar import. Similarly, the terms “first”, “second” and other such numerical terms referring to structures do not imply a sequence or order unless clearly indicated by the context. 
         [0063]    When introducing elements or features of the present disclosure and the exemplary embodiments, the articles “a”, “an”, “the” and “said” are intended to mean that there are one or more of such elements or features. The terms “comprising”, “including” and “having” are intended to be inclusive and mean that there may be additional elements or features other than those specifically noted. It is further to be understood that the method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order discussed or illustrated, unless specifically identified as an order of performance. It is also to be understood that additional or alternative steps may be employed. 
         [0064]    Various features of the invention are set forth in the following claims. It should be understood that the invention is not limited in its application to the details of construction and arrangements of the components set forth herein. The invention is capable of other embodiments and of being practiced or carried out in various ways. Variations and modifications of the foregoing are within the scope of the present invention. It also being understood that the invention disclosed and defined herein extends to all alternative combinations of two or more of the individual features mentioned or evident from the text and/or drawings. All of these different combinations constitute various alternative aspects of the present invention. The embodiments described herein explain the best modes known for practicing the invention and will enable others skilled in the art to utilize the invention.