Abstract:
A vent plug for a milking liner has a shielded inlet that reduces the likelihood that it will become clogged with debris from the floor of the milking parlor. In one embodiment, the vent plug has a plurality of redundant inlets that allow the vent plug to function if one of the inlets becomes clogged. In another embodiment, the inner flange of the body of the vent plug is at least twice the thickness of the body tube to help secure the vent plug in the milking liner.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application is a continuation-in-part application claiming priority from U.S. patent application Ser. No. 10/987,696 filed Nov. 12, 2004; which claims priority from U.S. Provisional Patent Application Ser. No. 60/583,705 filed Jun. 29, 2004; the disclosures of both are incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     1. Technical Field  
         [0003]     This invention generally relates to milking apparatus that use milking liners to draw milk from the teat. More particularly, the invention is related to the vent used with the milking liner. Specifically, the invention relates to anti-clogging vent plugs that may be selectively installed into and removed from milking liners.  
         [0004]     2. Background Information  
         [0005]     Automatic milking machines have been used to extract milk from different mammals through most of the past century. Most of these machines include a claw that typically has four nipples that are connected to teat cup assemblies that are attached to the teats. The teat cup assemblies include a rigid (hard plastic or metal) shell with a resilient, elastomeric milking liner (also known as a milking inflation) disposed within the shell. A short milk tube extends from the liner. A vacuum source is applied to the short milk tube and an alternating vacuum is applied to the shell to cause the liners to collapse and expand and thereby massage the teats and suck milk from the teats. The milk flows from the liners, into the short milk tube, to the nipples of the claw, and from there through a conduit to a collection tank.  
         [0006]     The liner is one of the few components of an automatic milking machine that comes into direct contact with the cow. Liners collapse and expand to massage the teat to cause milk to flow. Liner performance may be maximized with the proper pulsation ratio. Numerous milking inflation designs have been developed for collapsing on the teat in different manners. The art desires an inflation having an open, relatively large, readily collapsible barrel that uniformly collapses around the teat to provide effective and comfortable milking. The structure of the barrel should provide a reliable collapsing configuration and a long useful life. Liners that collapse and expand slowly are undesirable. Liners that pinch or otherwise irritate the teat are also undesirable.  
         [0007]     Air vents are also used with liners. The air vents are used to prevent the milk in the barrel or short milk tube of the liner from being drawn back towards the teat when the liner expands. An exemplary vent plug is shown in U.S. Pat. No. 6,055,931. A draw back with these types of vent plugs is that the air inlet opening is exposed to the environment under a cow and is frequently clogged by splattering debris (such as manure) from the floor in the milking parlor. Although the clog resistant air vent plug shown in U.S. Pat. No. 6,055,931 is effective, the art desires additional air vent plug designs that do not clog.  
       SUMMARY OF THE INVENTION  
       [0008]     In one configuration, the invention provides a vent plug for a milking liner wherein the inlet of the vent plug is shielded to reduce the likelihood that it will become clogged with debris from the floor of the milking parlor.  
         [0009]     Another aspect of one configuration of the invention is that the vent plug provides a plurality of redundant inlets that allow the vent plug to function if one of the inlets becomes clogged.  
         [0010]     Another configuration of the invention provides a vent plug having a spacer that is positioned at the outer flange between the inlet and the sidewall of the short milk tube.  
         [0011]     In a further embodiment, the invention provides an outer flange for a vent plug wherein the outer flange includes a cap that is snap into the outer flange.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]      FIG. 1  is an elevation view of a milking liner using the vent plug of the present invention.  
         [0013]      FIG. 2  is a section view of the vent plug of  FIG. 1 .  
         [0014]      FIG. 3  is a section view taken along  3 - 3  of  FIG. 2  showing one embodiment for the inlets.  
         [0015]      FIG. 4  is a view similar to  FIG. 3  showing an alternative embodiment for the inlets.  
         [0016]      FIG. 5  is a section view showing another alternative embodiment for the inlets.  
         [0017]      FIG. 6  is a section view taken along line  6 - 6  of  FIG. 2 .  
         [0018]      FIG. 7  is a view similar to  FIG. 6  showing an alternative flange configuration.  
         [0019]      FIG. 8  is a view similar to  FIG. 2  showing an alternative embodiment of the vent plug.  
         [0020]      FIG. 9  is a view similar to  FIG. 8  showing a further alternative embodiment of the vent plug.  
         [0021]      FIG. 10  is a view similar to  FIG. 2  showing an alternative embodiment of the vent plug.  
         [0022]      FIG. 11  is a section view taken along line  11 - 11  of  FIG. 10 .  
         [0023]      FIG. 12  is a view similar to  FIG. 10  showing an alternative inlet configuration. 
     
    
       [0024]     Similar numbers refer to similar parts throughout the specification.  
       DETAILED DESCRIPTION OF THE INVENTION  
       [0025]     The vent plug of the invention is indicated generally by the numeral  2  in the accompanying drawings. Vent plug  2  allows air to be drawn into a short milk tube  4  of a milking liner  6  when a barrel  8  of liner  6  is moving from the collapsed configuration toward the uncollapsed configuration to prevent milk from being drawn back towards barrel  8 . In the context of this application, the term “milking liner” or “liner” includes short milk tube  4  regardless of whether short milk tube  4  is integrally formed with barrel  8 .  
         [0026]     The air being drawn into short milk tube  4  through vent plug  2  is indicated by the numeral  10  in  FIGS. 2, 8 , and  9 . Vent plug  2  defines a vent passage  12  that extends entirely through vent plug  2  such that the passageway defined by short milk tube  4  is in fluid communication with the atmosphere surrounding the outer surface of short milk tube  4 . Vent passage  12  includes an outlet  14  adapted to be disposed inside liner  6  and at least one inlet  16  adapted to be positioned outside liner  6 . Inlet  16  faces the outer surface of liner  6  such that inlet  16  is protected from debris that may be splashed or splattered against the outer surface of vent plug  2 . This inlet  16  configuration requires air  10  to turn through a 180 degree curve before passing through vent plug  2 . Inlet  16  is thus disposed between at least a portion of the body of vent plug  2  and a portion of short milk tube  4  or between a portion of the body and outlet  14 .  
         [0027]     In the exemplary embodiments of the invention, inlet  16  may be provided in the form of a plurality of inlet holes  16  as shown in  FIGS. 3 and 4 . The use of more than one inlet hole  16  also makes vent plug  2  less likely to clog. Various inlet configurations are contemplated by the inventors including a single inlet  16  sized the same, smaller than, or larger than outlet  14  or a plurality of inlets  16 . Inlet holes  16  may be formed straight through (each having a longitudinal axis normal to the surface) the inwardly-facing body wall of vent plug  2  or may be tilted at an acute angle (such as having longitudinal axis disposed 15 to 75 degrees to the surface) as shown in  FIG. 5  to create a swirling air pattern within vent passage  12 . The configuration of inlet  16 , the use of multiple inlets  16 , and the location of inlets  16  between the body of vent plug  2  and the wall of short milk tube  4  makes vent plug  2  difficult to clog.  
         [0028]     The body of vent plug  2  generally includes a body tube  18 , an inner flange  20 , and an outer flange  22 . Inner flange  20  is pointed or in the form of a cone or a pyramid so that it may be forced through the opening defined by short milk tube  4  in order to install vent plug  2 . The outer corner  24  of flange  20  may be rounded to help flange  20  fit through the opening of short milk tube  4  so that it does not tear the material of short milk tube  4 . As shown in  FIG. 6 , the outwardly facing surface  26  of inner flange  20  is optionally formed with the same curvature as the inner surface  28  so that a tight seal is formed between flange  20  and short milk tube  4 . Similarly, the inwardly facing surface  30  of outer flange  22  has a curvature substantially similar to the curvature of the outer surface  32  of short milk tube  4  so that a tight seal is formed between vent plug  2  and milk plug  4 .  
         [0029]     An alternative embodiment of vent plug  2  is depicted in  FIG. 7  wherein flange  20  is hook shaped with outer corner  24  being sharply pointed. The sharp outer corner engages inner surface  28  to help prevent vent plug  2  from being unintentionally pulled out of place.  
         [0030]     In the exemplary embodiment, outer flange  22  includes two stepped portions. The first stepped portion engages the outer body wall of short milk tube  4 . The first stepped portion has a sidewall that defines the distance the second stepped portion is spaced from the outer surface of short milk tube  4 . The second stepped portion is spaced from the outer surface of the body wall of short milk tube  4  and provides an overhang that defines and shields inlet  16 . Each inlet  16  may be spaced from the sidewall of the first stepped portion as shown in  FIGS. 2 and 3 . The spacing helps prevent fluid and/or debris flowing down the outer surface of short milk tube  4  from resting on the sidewall of the first stepped portion and directly entering inlet  16 .  
         [0031]     In the exemplary embodiment, the inner surface of the overhang that defines inlet  16  is disposed 90 degrees with respect to the longitudinal axis of vent plug  2 . Inlet  16  thus faces liner  16  or faces toward inner flange  20 . In other embodiments, the inner surface of the overhang forms an acute or obtuse angle with the longitudinal axis of vent plug  2  causing inlet  16  to face inwardly at an angle.  
         [0032]     In an alternative embodiment of the invention, the first stepped portion defines inlet  16  through its sidewall. When inlet  16  is normal to the sidewall surface, air  10  must turn through a 90 degree curve before passing through vent plug  2 . In this alternative embodiment, the second stepped portion may shield inlet  16 . In another embodiment, the second stepped portion may be eliminated with only the corner between the outer surface of the stepped portion and the sidewall of the stepped portion protecting and shielding inlet  16 . Further, vent passage  12  may be acutely or obtusely angled (with respect to the longitudinal axis of vent plug  2 ) through the first stepped portion with inlet  16  exiting the sidewall at an angle facing liner  6  or facing away from liner  6 .  
         [0033]     Outer flange  22  may define a common vent chamber  40  when inlet  16  is in the form of multiple openings. Vent chamber  40  allows all the air  10  to mix from each inlet  16  and allows any debris that enters a single inlet hole  16  to fall to the bottom of vent plug  2  before being sucked through vent passage  12  into short milk tube  4 . In the exemplary embodiment, outer flange  22  includes a cap that is snap fit to the body of vent plug  2 . In other embodiments, outer flange  22  may be integrally formed. When the cap of outer flange  22  is removable, vent passage  12  may be cleaned by removing the cap and then cleaning passage  12 .  
         [0034]     Alternative embodiments of vent plug  2  are depicted in  FIGS. 8 and 9 . In these alternative embodiments, an impeller  42  is rotatably disposed within common vent chamber  40 . Impeller  42  freely rotates and is spun by air  10  being pulled through vent plug  2 . Impeller  42  can be used to keep chamber  40  clear of debris.  
         [0035]     A further alternative embodiment of the vent plug is indicated generally by the numeral  102  in  FIGS. 10 and 11 . Vent plug  102  allows air to be drawn into short milk tube  4  of milking liner  6  when barrel  8  of liner  6  is moving from the collapsed configuration toward the uncollapsed configuration to prevent milk from being drawn back towards barrel  8 .  
         [0036]     The air being drawn into short milk tube  4  through vent plug  102  is indicated by the numeral  110 . Vent plug  102  defines a vent passage  112  that extends entirely through vent plug  102  such that the passageway defined by short milk tube  4  is in fluid communication with the atmosphere surrounding the outer surface of short milk tube  4 . Vent passage  112  includes an outlet  114  adapted to be disposed inside liner  6  and at least one inlet  116  adapted to be positioned outside liner  6 . Inlet  116  is protected from debris that may be splashed or splattered against the outer surface of vent plug  102 . This inlet  116  configuration requires air  10  to turn through a 90 degree curve before passing through vent plug  102 . Inlet  116  is thus disposed between at least a portion of the body of vent plug  102  and a portion of short milk tube  4  or between a portion of the body and outlet  114 .  
         [0037]     In the exemplary embodiments of the invention, inlet  116  may be provided in the form of a plurality of inlet holes  116 . Although only two inlet holes are depicted in the exemplary drawings, an array of inlet holes  116  may be used to allow air to be drawn into vent passage  112 . The use of more than one inlet hole  116  also makes vent plug  102  less likely to clog. Various inlet configurations are contemplated including a single inlet  116  sized the same, smaller than, or larger than outlet  114  or a plurality of inlets  116 . Inlet holes  116  may each having a longitudinal axis normal to the surface of vent lug  102  where inlet  116  exits the body of vent plug  102  or may be tilted at an angle as shown in  FIG. 12 . The configuration of inlet  116 , the use of multiple inlets  116 , and the location of inlets  116  make vent plug  2  difficult to clog.  
         [0038]     The body of vent plug  102  generally includes a body tube  118 , an inner flange  120 , and an outer flange  122 . Inner flange  120  is pointed or in the form of a cone or a pyramid so that it may be forced through the opening defined by short milk tube  4  in order to install vent plug  102 . Inner flange  120  may have a configuration similar to inner flange  20  described above, although it has been that it is desirable to size inner flange  120  to have an outer dimension  121  that is greater than twice the thickness  123  of body tube  118  so that vent plug  102  is not easy to remove from short milk tube  4  after it is installed.  
         [0039]     In one configuration, inlet  116  may be disposed directly in body tube  118  between the wall of short milk tube  4  and outer flange  122 . In the exemplary embodiment, outer flange  122  includes an outer wall  124  and a spacer  126 . Wall  124  and spacer  126  may have the same outer dimensions but spacer  126  may be smaller in some configurations. Spacer  126  engages the outer body wall of short milk tube  4 , helps to secure vent plug  102  in short milk tube  4 , and prevents inlets  116  from being obstructed by short milk tube  4 . Outer wall  124  shields inlet  116 . A portion of outer wall  124  is disposed in a position that locates at least a portion of inlet between outer wall  124  and short milk tube  4 .  
         [0040]     Outer wall  124  also defines an opening and a tooth  130  that extends into the opening. A cap  132  is snap fit into opening. This configuration allows vent plug  102  to be fabricated and reliably assembled.  
         [0041]     In the foregoing description, certain terms have been used for brevity, clearness, and understanding. No unnecessary limitations are to be implied therefrom beyond the requirement of the prior art because such terms are used for descriptive purposes and are intended to be broadly construed.  
         [0042]     Moreover, the description and illustration of the invention is an example and the invention is not limited to the exact details shown or described.