Abstract:
A system for positioning a seal member on a movable valve stem. The system includes an O-ring surrounding a lower portion of a movable valve stem. A snap-on retaining collar is pushed into place along the valve stem. A lower edge of the collar contacts the O-ring. The interaction between the snap-on collar and the O-ring prevents the O-ring from flexing outwardly and becoming dislodged from the valve stem. The snap-on retaining collar can be formed from various materials, such as but not limited to plastic.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    The present application is based on and claims priority to U.S. Provisional Patent Application Ser. No. 61/901,605 filed Nov. 8, 2013, the disclosure of which is incorporated herein by reference. 
     
    
     BACKGROUND 
       [0002]    The present disclosure generally relates to a dispensing valve. More specifically, the present disclosure relates to a dispensing valve that includes an O-ring retention system to prevent the O-ring from becoming dislodged from a movable valve stem in the dispensing valve. 
         [0003]    In a typical construction of dispensing valves, the dispensing valve includes a valve stem that is movable between an open and a closed position. In the closed position, the valve stem prevents the flow of liquid from an inlet to an outlet. 
         [0004]    In many dispensing valves, a sealing member, such as an O-ring, is positioned on the valve stem to provide a liquid tight seal between the valve stem and a valve seat when the valve is in a closed position. In applications where the dispensing valve is used with relatively high pressure fluids, the high pressure fluids can force the O-ring off of the valve stem during movement from the closed position to an open position. Therefore, a need exists for a retention system that holds an O-ring on the valve stem during use. 
       SUMMARY 
       [0005]    The present disclosure relates to a dispensing valve in which an inexpensive O-ring can be purchased in any number of materials, sizes and durometers. The O-ring forms a face seal with a valve seat when the valve stem is in the closed. condition. Typically, O-rings are not used as face seals since the water pressure acts on the O-ring to force it off of the movable valve stem as the movable valve stem is titled off the valve seat. This is primarily true when higher differential pressures are used. 
         [0006]    The present disclosure utilizes a snap-on collar that captures the O-ring between the collar and the valve stem. The snap-on collar prevents the O-ring from lifting off of the valve stem during movement of the valve stem between the open and closed conditions. 
         [0007]    The present disclosure further relates to a dispensing valve that includes a valve body having an inlet and an outlet. The dispensing valve includes a valve stem that is movable within the valve body between an open position and a closed position. When the valve stem is in the closed position, the valve stem prevents the flow of liquid from the inlet to the outlet. In the open position, the valve stem allows fluid to flow from the inlet to the outlet. 
         [0008]    The dispensing valve further includes an O-ring that is mounted to an outer surface of the valve stem. Specifically, the O-ring is received within a sealing groove that is formed in the valve stem at or near an outer end of the valve stem. The resilient nature of the O-ring holds the O-ring within the sealing groove. 
         [0009]    In one embodiment of the disclosure, the dispensing valve includes a bias spring that urges the valve stem toward the closed position. In such an embodiment, the dispensing valve includes an actuator that moves the valve stem against the bias force created by the bias spring toward an open position. 
         [0010]    The valve stem includes a retaining collar that is snap tit onto the valve stem. When the retaining collar and O-ring are both mounted to the valve stem, the retaining collar at least partially surrounds the O-ring to hold the O-ring in position on the valve stem. The retaining collar is configured to have a bottom end that is generally aligned with an equator of the O-ring to prevent both expansion of the O-ring and restrict the flow of pressurized liquid between the O-ring and the valve stem. 
         [0011]    In one embodiment of the disclosure, the retaining collar is formed from a plastic material. The retaining collar can include one or more slots that allow the top end of the collar to flex outward and create a snap fit of the retaining collar onto the valve stem. 
         [0012]    Various other features, objects and advantages of the invention will be made apparent from the following description taken together with the drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]    The drawings illustrate the best mode presently contemplated of carrying out the disclosure. In the drawings: 
           [0014]      FIG. 1  is an isometric view of a dispensing valve constructed in accordance with the present disclosure; 
           [0015]      FIG. 2  is a section view of the dispensing valve in a closed position; 
           [0016]      FIG. 3   a  is a section view of the dispensing valve in the open position; 
           [0017]      FIG. 3   b  is as magnified view of the valve stem in the open position; 
           [0018]      FIG. 4   a  is a section view of the dispensing valve in the closed position; 
           [0019]      FIG. 4   b  is a magnified view showing the valve stem in the closed position; 
           [0020]      FIG. 5  is a magnified view illustrating the position of a snap-on collar on the valve stem to retain a sealing O-ring; 
           [0021]      FIG. 6  is an isometric view of the snap-on collar shown in  FIGS. 5 ; and 
           [0022]      FIG. 7  is a section view of the snap-on collar taken along line  7 - 7  of  FIG. 6 . 
       
    
    
     DETAILED DESCRIPTION 
       [0023]      FIG. 1  illustrates a dispensing valve  10  constructed in accordance with the present disclosure. The dispensing valve  10  includes a solenoid actuator  12  mounted on a valve body  14 . The valve body  14  includes a fluid inlet  16  that receives a supply of liquid that passes through the valve body  14  and is dispensed from an outlet  18 . As best illustrated in  FIG. 2 , the inlet  16  receives a collet  20  while the outlet  18  receives a similar collet  22 . A sealing member, such as an O-ring  24 , is positioned within both the inlet  16  and the outlet  18 . 
         [0024]    The flow of fluid from the inlet  16  to the outlet  18  is controlled by the position of a movable valve stem  26 . The valve stein  26  is biased into the closed position shown in  FIG. 2  by a bias spring  28 . An electromagnetic coil  30  surrounds the valve stem  26  and can be activated to move the valve stem  26  upward against the bias force created by the spring  28  into an open position, as shown in  FIG. 3   a . When in the open position, the bottom face surface  32  of the valve stem is spaced above a valve seat  34 , as best illustrated in  FIG. 3   b , to allow fluid flow through the valve body  14 . The flow of fluid is illustrated by arrow  36 . 
         [0025]      FIGS. 4   a  and  4   b  illustrate the valve stem  26  in the closed position. As illustrated best in  FIG. 4   b , when the valve stem  26  is in the closed position, an O-ring  38  mounted near the end of the valve stem  26  is pressed into contact with a sealing outer edge  40  of the valve body  14  that defines the valve seat  34 . The bias force created by the spring  28  provides the required sealing force between the O-ring  38  and the valve seat  34 . 
         [0026]    As illustrated in  FIG. 4   b , the O-ring  38  is received within a sealing groove  42  formed at the outer end  43  of the valve stem  26 . The resilient nature of the O-ring  38  generally holds the O-ring  38  within the sealing groove  42  during normal conditions, as shown in  FIG. 4   b . 
         [0027]    When the valve stem  26  begins to move upward from the closed position of  FIG. 4   b  to the open position of  FIG. 3   b , the high pressure flow of fluid, illustrated by arrow  44  in  FIG. 4   b , contacts the O-ring  38 , urging the O-ring to stretch and be pushed off of the outer end  43  of the valve stem  26 . 
         [0028]    If the O-ring  38  were used alone on the outer end  43  of the valve stem  26 , the high pressure fluid flow may cause the O-ring  38  to become separated from the valve stem  26 , which would render the dispensing valve inoperable. To address this issue, the valve stem  26  includes a retention system that includes a retaining collar  46 . As illustrated in  FIG. 4   b , a bottom end  48  of the collar extends to the approximate equator of the O-ring  38 . The collar  46  thus prevents the high pressure fluid flow from flowing between the O-ring  38  and the sealing groove  42 . Thus, the O-ring  38  cannot flex outward and become dislodged from the outer end  43  of the valve stem  26 . 
         [0029]      FIG. 5  illustrates the position of the retaining collar  46  along the lower portion  52  of the valve stem  26 . As indicated previously, the bottom end  48  of the collar  46  extends to a position approximately aligned with an equator  61  of the O-ring  38 . The collar  46  thus prevents the O-ring  38  from flexing and becoming dislodged from the lower portion  52  of the valve stem  26 . In the preferred embodiment of the disclosure, the collar  46  includes a protruding finger  54  on the top end  56 , as illustrated in  FIGS. 5 and 6 . The finger  54  is received within a collar groove  58  machined into an outer surface  59  of the valve stem  26 . In the embodiment illustrated, the collar  46  is formed from a flexible plastic material, although other materials are contemplated. 
         [0030]    As shown in  FIG. 6 , the collar  46  includes a pair of open slots  60  that allow the top end  56  of the collar  46  to flex outward. The flexing of the collar  46  allows the collar  46  to snap into place along the valve stem  26 , as shown in  FIG. 5 . When in position as shown in  FIG. 5 , the material properties of the collar  46  hold the protruding finger  54  formed on the top end  56  in the collar groove  58 . 
         [0031]    The section view of  FIG. 7  illustrates the depth of each of the pair of open slots  60 . The open slots  60  allow the top end  56  of the collar  46  to expand and snap back into the retaining position shown in  FIG. 5 . Although the pair of open slots  60  are illustrated in  FIGS. 6 and 7 , it is contemplated that the open slots  60  could be eliminated if the collar  46  is made of a material that has sufficient resilient properties such that it can flex when pushed onto the lower portion  52  of the valve stem  26  and snap back into the position shown in  FIG. 5 . 
         [0032]    Referring back to  FIG. 5 , the steps in assembling the valve stem will now be discussed. Initially, the O-ring  38  is pushed onto the valve stem until the O-ring  38  is received within the sealing groove  42  (see  FIG. 4   b ). Once the O-ring  38  is in position, the collar  46  is positioned beneath the valve stem  26 . The collar  46  is then aligned with the valve stem and pushed upward. During this movement, the O-ring  38  is received within the open top end and the collar  46  is pushed further upward until the fingers  54  reach the groove  58 . Once the fingers  54  reach the collar groove  58 , the fingers are received within the collar groove  58  to hold the collar in position as shown. 
         [0033]    As discussed previously, the bottom end  48  of the collar is generally aligned with the equator  61  of the O-ring  38 . Thus, the outer wall  64  of the collar  46  prevents liquid from directly flowing into contact with the O-ring  38  at a location above the equator  61 . In addition, due to the close spacing between the inner surface  66  of the outer wall  64  and the outer surface  68  of the O-ring  38 , the collar  46  prevents the O-ring  38  from expanding outward. In this way, the collar  46  prevents the dislodgement of the O-ring  38  from the valve stem  26  during movement of the valve stem from the closed position to the open position. 
         [0034]    This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to make and use the invention. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.