Abstract:
A self-venting drain valve for draining liquid from a vessel having an end opening through which liquid may drain and gas may simultaneously enter. The drain valve comprises a body portion and a stem portion. The body portion having a substantially tubular, internally threaded section and a vent permitting gas to enter. The stem portion has an externally threaded section and an aperture where liquid is permitted to drain from the vessel. The stem portion can be closed by engaging the externally threaded section with the internally threaded section, thereby preventing liquid and gas flow by sealing the vent and the aperture. The stem portion can be opened by disengaging the externally threaded section from the internally threaded section, thereby permitting liquid and gas flow simultaneously and separately by unsealing the aperture to permit liquid to drain from the vessel and unsealing the vent to permit gas to enter the vessel

Description:
CROSS REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims the benefit of U.S. Patent Application Ser. No. 60/895,129, filed Mar. 15, 2007, the contents of which are incorporated herein by reference thereto. 
     
    
     BACKGROUND 
       [0002]    The present invention relates to self-venting valves, and, more particularly, to self-venting valves for draining water from fuel filter assemblies. 
         [0003]    Various assemblies of self-venting liquid drain valves have been produced to provide for fluid drainage from a closed vessel. For example, in fuel/water separators used in internal combustion engines, water must be periodically drained using a valve assembly that is adapted to permit air to enter into a separator while the water is being drained. Some devices accomplish this by providing separate gas and liquid passages formed through portions of the valve assembly member. The separate passage for gas, such as air, is included in these devices to replace the liquid being drained 
         [0004]    A problem that arises with fluid filter assemblies, particularly with those used for diesel and gasoline marine engines, is the removal of contaminants from the filter assembly. As fluid flows through a filter element, contaminants are separated therefrom and collect at the bottom of the vessel that is used to retain the filter element. These contaminants can include water and particulate matter suspended in the water, and must be periodically drained from the vessel. To remove these contaminants, drain valves are frequently positioned at the bottom of vessels. If a simple drain cock is utilized for the valve, the drainage may not be complete or may not occur at all because a partial vacuum is created in the filter housing upon the opening the valve assembly and initiation drainage. The partial vacuum prevents water from flowing through the open valve. Thus, rapid and complete draining can be effected only if ambient air is admitted into the vessel to break the vacuum therein. 
         [0005]    To facilitate drainage by breaking the partial vacuum, many drain valves in fuel filters are self-venting, that is, they can allow ambient atmosphere to enter the filter when the valve is opened using vent holes. These vent holes, however, must be sealed when the valves are closed so that fluid within the fluid filter does not flow out through the vent holes. 
         [0006]    Although current valve assemblies have been generally useful, they have had numerous disadvantages. Those which are self-venting have often been complex and made of multiple parts, making them expensive to manufacture and difficult to assemble. For example, some designs require one or more springs and/or a relatively complex arrangement of seals. Additionally, some drain assemblies have the disadvantage of allowing liquid drainage to leak through air vent passages. In fact, some valve assembly designs may initially draw drainage liquid into the vent passage during opening. 
         [0007]    Accordingly, it is desirable to provide a self-venting drain valve for selectively permitting and preventing draining of contaminant liquid, such as water, from filter assembly housings and the like that is simple in construction, compact, inexpensive, reliable, and configured for ease of assembly and operation. 
       SUMMARY OF THE INVENTION 
       [0008]    Disclosed herein are exemplary embodiments of a self-venting drain valve for draining liquid from a vessel having an end opening through which liquid may drain and gas may simultaneously enter. The drain valve comprises a body portion and a substantially tubular stem portion. The body portion has an upper end, a lower end, and a substantially tubular, internally threaded section. The internally threaded section defines a body aperture opening at the upper end and extending therethrough to the lower end. The upper end is configured to be fixedly mounted on the vessel in coaxial alignment with the end opening. The body portion has a vent formed in the lower end. The stem portion has an exterior surface, an interior surface, an upper section, and an externally threaded lower section. The interior surface defines a stem aperture opening at the upper section and extending therethrough to the lower section. The stem portion has a groove formed in the lower section and opening radially through the exterior surface. The groove forms a first fluid passage through the stem aperture. The vent forms a second fluid passage through the body aperture between the internally threaded section of the body portion and the exterior surface of the stem portion. The stem portion is disposed and selectively positionable within the body aperture between a closed position and an open position. The stem portion can be positioned in the closed position by moving the stem portion upwardly through the body aperture into the vessel and threadably engaging the externally threaded lower section with the internally threaded section of the body portion. The stem portion thereby cooperates with the body portion when in the closed position to prevent liquid and gas flow through the fluid passages by sealing the vent and the groove. The stem portion can be positioned in the open position by threadably disengaging the externally threaded lower section from the internally threaded section of the body portion and moving the stem portion downwardly through the body aperture to engage the upper section with the body portion. The stem portion thereby cooperates with the body portion when in the open position to permit liquid and gas flow simultaneously and separately in the fluid passages by unsealing the groove to permit liquid to drain from the vessel through the first fluid passage and unsealing the vent to permit gas to enter the vessel through the second fluid passage. 
     
    
     
       DESCRIPTION OF THE DRAWINGS 
         [0009]      FIG. 1  is a cross-sectional view of an exemplary embodiment of a self-venting drain assembly in accordance with the present invention with the assembly in the closed position; 
           [0010]      FIG. 2  is a cross-sectional view of the exemplary self-venting drain assembly of  FIG. 1  with the assembly in the open position; 
           [0011]      FIG. 3  is a perspective view of the exemplary valve element of the exemplary drain assembly of  FIGS. 1 and 2 ; and 
           [0012]      FIGS. 4 and 5  are bottom and top elevational views of the exemplary valve element of  FIG. 3 . 
       
    
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
       [0013]    While the specification concludes with claims defining the features of the invention that are regarded as novel, it is believed that the invention will be better understood from a consideration of the description of exemplary embodiments in conjunction with the drawings. It is of course to be understood that the embodiments described herein are merely exemplary of the invention, which can be embodied in various forms. Therefore, specific structural and functional details disclosed in relation to the exemplary embodiments described herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the present invention in virtually any appropriate form. 
         [0014]    Furthermore, the terms and phrases used herein are not intended to be limiting but rather to provide an understandable description of the invention. For instance, throughout the present specification, relative positional terms like ‘upper’, ‘lower’, ‘top’, ‘bottom’, ‘horizontal’, ‘vertical’, and the like are used to refer to the orientation of the exemplary embodiments shown in the drawings. These terms are used in an illustrative sense to describe the depicted exemplary embodiments and are not meant to be limiting. It will be understood that in particular applications, a valve assembly may be installed in an orientation different from that shown in the drawings (for example, inverted 180 degrees or transverse to that shown), and in such a case, the above-identified relative positional terms will no longer be accurate. 
         [0015]    In accordance with the present invention, an exemplary embodiment of a self-venting drain valve assembly is illustrated in  FIGS. 1 and 2 . The valve assembly, indicated generally by 2, is illustrated in combination with a vessel  4  that may be a portion of the housing of a water/fuel separator. Such separators are frequently installed on the vacuum side of a fuel pump, which thereby subjects the interior of the housing to sub-atmospheric pressure. A compression spring (not shown) operates to properly position a filter (not shown) within the water/fuel separator. The structure of a conventional separator is well known and does not constitute any part of exemplary embodiments of a valve assembly in accordance with the present invention. 
         [0016]    During operation of a water/fuel separator, water accumulates in the bottom portion of vessel  4 . Solid particulate contaminants also tend to fall out of the fuel and water and accumulate in the space in the bottom of vessel  4 . The accumulated water and contaminants are drained periodically to permit continued satisfactory operation of the separator. To perform this function, exemplary valve assembly  2  provides a drain path through which liquid collected in the base of vessel  4  may be drained out of the vessel while providing an independent passage for gas to enter vessel  4  simultaneously to break the vacuum within the vessel and facilitate drainage. As explained in greater detail below, valve assembly  2  provides a self-venting feature by a structure which is simple and inexpensive to manufacture. 
         [0017]    Self-venting drain valve assembly  2  includes a substantially tubular collar or body portion  8 , which is preferably of a one-piece construction, and a valve element  14 , which is also preferably of a one-piece construction. Body portion  8  is disposed in an end opening  12  at the bottom surface  10  of vessel  4  that is coaxial with the vertical axis  20  of the vessel. As will be described below, valve element  14 , which is selectively movable relative to body portion  8  between a fully closed position, depicted in  FIG. 1 , and a fully open position, depicted in  FIG. 2 , cooperates with body portion  8  to define flow paths for liquid and air. 
         [0018]    Body portion  8 , which may take the form of an annular weld nut in exemplary embodiments, is adapted to be fixedly mounted to the bottom of vessel  4 . Body portion  8  includes a flanged upper end  52  and an opposing lower end  54 . Upper end  52  projects substantially vertically through end opening  12  and into vessel  4 , and lower end  54  is disposed outside the vessel. Body portion  8  has an annular internally threaded section  56  that defines a body aperture  58  in fluid communication with vessel  4 . Body aperture  58  opens at upper end  52  in coaxial alignment with end opening  12  of vessel  4  and extends through body portion  8  to lower end  54 . 
         [0019]    Valve element  14  comprises a homogenously formed one-piece unitary valve body that, in exemplary embodiments, can be made of relatively lightweight and low-cost synthetic plastic materials that do not corrode when exposed to liquid flowing therethrough such as, for example, nylon 6/6 or glass filled nylon 6/6. In exemplary embodiments, valve element  14  is manufactured by injection molding. Alternatively, non-plastic corrosion-resistant materials, such as stainless steel or aluminum, may be used for manufacturing valve element  14 . In alternative exemplary embodiments that permit the valve assembly to be used in marine applications, valve element  14  may be formed of die-cast zinc. Valve element  14  includes a stem portion  16  and a bottom portion  22  integrally juxtaposed to the lower end of the stem portion. Bottom portion  22  includes a radial flange  24  and a collector knob or operator  32  disposed around bottom portion  22  to facilitate manual rotation of valve element  14  and to assist in draining liquid, as discussed below. 
         [0020]    Valve element  14  is rotatably and slidably received within body aperture  58  for reciprocating upward and downward movement within between a closed position, illustrated in  FIG. 1 , and an open position, illustrated in  FIG. 2 , with valve stem portion  16  extending through the body aperture  58  and bottom portion  22  being positioned outside vessel  4 . When valve element  14  is in the open position, gas enters and liquid drains from vessel  4  along separate paths. 
         [0021]    Stem portion  16  is generally cylindrical in shape and includes a substantially tubular wall section  44  defining an internal drain passage  18  through which liquid such as water collected in the bottom portion of vessel  4  may be drained out of the vessel. Drain passage  18  extends lengthwise through stem portion  16  between a radial cutout groove  42  and an upper drain port  60  at the top of the stem portion, as best illustrated in  FIG. 2 , and includes two segments, axial passage  38  and radial passage  40 . Radial passage  40  and axial passage  38  are disposed at substantially 90° right angles to each other. Radial passage  40  opens at groove  42 , through which liquid can drain out from vessel  4  and drain passage  18 . A pair of opposing retaining nibs  36  project radially outward from a point adjacent to upper drain port  60  at the top of stem portion  16 . Retaining nibs  36  are adapted to engage the top surface  62  of internally threaded section  56  of body portion  8  to retain valve element  14  within the body portion when valve assembly  2  is in the open position, as illustrated in  FIG. 2 . In exemplary valve assembly  2  of  FIGS. 1 and 2 , retaining nibs  36  are diametrically opposed at the top of stem portion  16 . 
         [0022]    An externally threaded section  34  is disposed between wall section  44  and bottom portion  22  on stem portion  16 , in axial alignment with groove  42 . Externally threaded section  34  is configured to be received within and threadably mate internally threaded section  56  of body portion  8 . When valve assembly  2  is in the closed position, externally threaded section  34  engages internally threaded section  56 , as shown in  FIG. 1 , to close off groove  42  and thereby seal radial passage  40  so that liquid in vessel  4  cannot drain from the water/fuel separator. 
         [0023]    As described above, valve element  14  provides drain passage  18  through which liquid collected in the bottom portion of vessel  4  may be drained out from the vessel. Valve element  14  also cooperates with body portion  8  to provide an air passage  64  extending axially within body aperture  58  in the space defined between internally threaded section  56  of body portion  8  and the opposing wall section  44  of stem portion  16 . When valve assembly  2  is disposed in the open position of  FIG. 2 , air passage  64  permits gas to enter vessel  4  and break the partial vacuum within the vessel, thereby facilitating the drainage of liquid through drain passage  18 . As illustrated in  FIG. 2 , an annular air vent  66  axially formed through lower end  54  of body portion  8  provides an opening that communicates with ambient atmosphere to admit air into vessel  4  via passage  64 . Air passage  64  thus extends independently of drain passage  18  within body portion  8  from air vent  66  to an annular upper air outlet port  68  axially formed in top surface  62  of internally threaded section  56  and in communication with the air passage. 
         [0024]    As is illustrated in  FIG. 2 , when self-venting drain valve assembly  2  is in the open position, liquid flows in the path of arrow  51  through axial passage  38  of valve element  14  and drains out from radial passage  40  through groove  42 , while gas follows the path of arrows  53  into vessel  4  to prevent a partial vacuum from occurring therein that would interfere with the flow of liquid out of the valve element. Stem portion  16  fits within body aperture  8  to isolate air passage  64  from drain passage  18  and thereby constrain liquid and air to flow along separate paths. Thus, valve assembly  2  provides a self-venting feature in a structure that is simple and inexpensive to manufacture. It preferable that the ratio of the area of outlet groove  42  to the area of inlet air vent  66  be between 10 and 20, and, more preferably, 15. 
         [0025]    When exemplary valve assembly  2  is installed on a water/fuel separator, because water is heavier than fuel, water can accumulate in the bottom of vessel  4  while fuel remains above the top surface of the water. Valve element  14  is can thus be held in the  FIG. 2  position by the person draining water from the water/fuel separator until only fuel drains therefrom. 
         [0026]    The exemplary valve assembly that is illustrated in  FIGS. 1 and 2 , by providing an isolated air passage that axially extends in the space defined between internally threaded section  56  of body portion  8  and the opposing wall section  44  of stem portion  16 , allows the length of the stem portion that is required for the valve assembly to be functional to be minimal. Thus, exemplary embodiments of a valve assembly in accordance with the present invention can be provided with a compact design that facilitates drainage of vessel  4  with minimal internal clearance requirements. When exemplary valve assembly  2  is in the open position, air outlet  68  and groove  42  are separated by a distance that is indicated by reference letter A in  FIG. 2 . In exemplary embodiments, distance A can be, for instance, one-half inch long. 
         [0027]    In the present exemplary embodiment, during the opening of valve assembly  2 , groove  42  opens slightly before air vent  66  opens to provide the proper flow sequencing. While air passage  64  remains sealed by externally threaded section  34  of stem portion  16  until valve element  14  is completely threadably disengaged from body portion  8 , groove  42  becomes partially unsealed prior to valve element  14  being completely threadably disengaged from body portion  8 . Additionally, wall section  44  of stem portion  16  is positioned between externally threaded section  34  and upper drain port  60  to allow liquid to flow into drain passage  18  at a point remote from gas flowing from air passage  64  through air vent  66  into vessel  4 . Incoming gas, in the form of bubbles, is prevented from being pulled into the liquid drainage because wall section  44  cooperates with flanged upper end  52  of body portion  8  to force the air bubbles to rise upwardly away from the region of higher water velocity. 
         [0028]    A gasket  46  is disposed circumferentially around the bottom of stem portion  16  just below externally threaded section  34 . As shown in  FIG. 1 , when valve assembly  2  is disposed in the closed position, gasket  46  is trapped by a downwardly projecting annular protecting rib  70  at lower end  54  of body portion  8 . The inner diameter of rib  70  is slightly larger than the outer diameter of gasket  46  to center the gasket on body portion  8  and prevent overtightening. 
         [0029]    Gasket  46  thereby cooperates with lower end  54  and internally threaded section  56  of body portion  8  to effectively seal both air vent  66  and groove  42  to prevent gas and liquid flow to and from vessel  4  when valve assembly  2  is in the closed position. In exemplary embodiments, gasket  46  can be adhered to stem portion  16  or not bonded to any surface. In exemplary embodiments, gasket  46  can be in the form of a conventional O-ring made of any appropriate elastic material, such as rubber or nitrile. 
         [0030]    Gasket  46  is the only gasket required. Thus, exemplary valve assembly  2  can be provided using only a single sealing surface. Additional radial seals or gaskets are unnecessary, thereby greatly simplifying the assembly and production processes and simplifying the configuration of the valve assembly. 
         [0031]    When valve assembly  2  is disposed in the closed position shown in  FIG. 1 , valve element  14  is threadably engaged with body portion  8  in its upper-most position, with externally threaded section sealing off air passage  64  to close off communication between air vent  66  and vessel  4 . Further, internally threaded section  56  of body portion  8  seals against groove  42  such that communication between drain passage  18  and vessel  4  is also closed. Also, gasket  46  is positioned to prevent leakage around that interface. Thus, both drain passage  18  and air passage  64  are sealed against communication with vessel  4 . 
         [0032]    To open valve assembly  2  when valve element  14  is threadably engaged with body portion  8  in the closed position, the valve element can be rotated and unscrewed to threadably disengage externally threaded section  34  of stem portion  16  from internally threaded section  56  of base portion  8 . Wall section  44  of stem portion  16  can then be moved downwardly through body aperture  58  and bottom surface  10  of vessel  4  until retaining nibs  36  engage top surface  62  of internally threaded section  56  to retain valve assembly  2  in the open position and prevent stem portion  16  from falling out of the vessel. At this point, liquid in vessel  4  will siphon out of the vessel from upper drain port  60  through drain passage  18 . 
         [0033]    During the process of opening of valve assembly  2 , the partial unscrewing of the engagement between the threaded sections results in a lower portion of groove  42  becoming unsealed below lower end of body portion  54  such that drain passage  18  becomes free to communicate with vessel  4 . That is, contaminant liquid may then proceed at least partially down drain passage  18 . At this stage, the isolation in air passage  64  between air vent  66  and air outlet port  60  is maintained by externally threaded surface  34  of stem portion  16  until externally threaded section  34  is completely disengaged from internally threaded section  56  of base portion  8 . Thus, depending upon the type of liquid being drained, as well as other factors, the liquid drainage may be halted by a partial vacuum formed by the partial exiting of some liquid, or, alternately, may flow out in irregular fashion caused by the partial vacuum. 
         [0034]    Upon moving valve element  14  further downward to the open position of  FIG. 2 , both groove  42  and externally threaded section  34  will have become entirely clear of both internally threaded section  56  and air vent  66 . With valve assembly  2  then fully open, liquid drainage from vessel  4  can proceed rapidly through drain passage  18  and out of groove  42 . Venting gas can freely proceed through air passage  64  to replace the drained liquid in vessel  4 , thereby avoiding any partial vacuum which might otherwise form. By virtue of the timed opening in which groove  42  communicates with upper drain port  60  and vessel  4  before air vent  66  communicates with upper air outlet  68  and the vessel, virtually no liquid drainage will occur through air passage  64 . Thus, in this arrangement, threaded sections  34  and  56  are quite removed from the drainage liquid. 
         [0035]    When valve assembly  2  is in the open position, liquid will be siphoned through drain passage  18  because the lower portion of the drain passage (that is, radial passage  40  and groove  42 ) is lower than the point of entry of air into vessel  4  as allowed by air outlet port  68 . As discussed above, this distance, indicated by reference letter A in  FIG. 2 , should be at least approximately one-half inch to provide the proper siphoning of liquid from the vessel under vacuum conditions. After liquid exits drain passage  18  through radial passage  40  and groove  42 , it is caught by valve operator  32 . 
         [0036]    Reference is now specifically made to  FIGS. 3-5 , which illustrate more completely the features of exemplary valve element  14 . Valve operator  32  includes a substantially annular groove  48  facing stem portion  16  and defining a drain reservoir, and a drain spout  30  forming an axial cutout passage  28  through which the water drains. Cutout passage  28  is open to the drain reservoir at an upper end thereof, and to the ambient atmosphere at a lower end thereof. Drain spout  30  allows connection of a hose to drain fluid into a container without spillage. Additionally, valve operator  32  is cup-shaped to accumulate liquid being drained and also collects any liquid which may leak through the space between externally threaded portion  34  of stem portion  16  and internally threaded section  56  of body portion  8  when valve assembly  2  is in the closed position. A generally cylindrical outer peripheral surface  50  of valve operator  32  can be provided with axially oriented ribs  26  to facilitate manual gripping of the valve operator. 
         [0037]    In an alternative exemplary embodiment, bottom portion  22  of valve element  14  can include a cutout to facilitate rotation of the valve element  14  between the closed position and the open position using a metric wrench. The wrench socket may be of any appropriate shape, such as hexagonal or square. 
         [0038]    The exemplary embodiments of a valve assembly described herein can provide a simple self-venting liquid valve using only one gasket seal to achieve the two isolated liquid and gas flow passages. Liquid such as water is permitted to drain while gas such as air can enter the vessel to replace the liquid being drained, thereby facilitating drainage even when the vessel is subjected to a vacuum. The gas does not mix with the draining liquid in the valve assembly and does not interfere with the draining of liquid from the vessel. The exemplary embodiments described herein can be is relatively simple and inexpensive to manufacture because of the simplicity of design. 
         [0039]    While the invention has been described with reference to one or more exemplary embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.