Abstract:
A variable shut off teat cup liner has a mouthpiece, a barrel and a short milk tube adapted for mounting onto milking claw. The short milk tube includes a segment for engagement with an edge of a claw nipple defining an opening, the segment being intended for bending over the opening to substantially close it to passage of vacuum-drawn air therethrough when the teat cup liner is in a non-milking generally downwardly bending position. The segment has circumferentially extending grooves and longitudinally extending grooves which form lugs which provide improved cut resistance. The circumferentially extending grooves have different axial spacing whereby the amount of overlap of the short milk tube over the nipple may be varied to provide the proper amount of bending.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention is concerned with a teat cup liner, also known as an inflation, for a teat cup which is designed to permit mounting of the liner on a milking claw to provide resistance to cuts and variable amenability to closure of the opening of a corresponding nipple in the milking claw when the liner is in a hanging, non-milking position. By resisting cuts and providing such closure in the non-milking position, the liner reduces the flow of vacuum-drawn air through the channel of the liner and thereby saves energy by reducing the demand on the vacuum pump. 
     2. Description of the Prior Art 
     In typical dairy applications, conventional automatic milking machines utilize a plurality of teat cup assemblies connected to a common milk claw. Each of the teat cup assemblies include a hollow outer shell or cup attached to a pulsation line which typically alternates between a vacuum and atmospheric pressure. An inflation or teat cup liner is provided within the teat cup and extends axially along the length thereof. The liner includes a mouthpiece which extends from one end of the teat cup to seal one end of the cup and to receive a teat of an animal to be milked therein, a barrel which surrounds at least a portion of the teat and flexes according to the pulsating pressure, and a short milk tube which extends from and seals the other end of the teat cup for connection to the milking claw. A constant vacuum is drawn through the claw and the liner during milking to extract milk from the animal. Thus, the interior milk and vacuum conveying channel within the liner is maintained at constant sub-atmospheric conditions. A vacuum pump is operable connected to the milking claw by, inter alia, a long milk tube, the vacuum pump being connected to a source of power to create the necessary vacuum for milk extraction. 
     During milking, the annular region between the cup and the liner is subjected to alternating subatmospheric pressure and a higher, typically atmospheric pressure, while the mouth of the liner is positioned in sealing engagement with the teat. The barrel wall alternately flexes inwardly toward the teat in the teat-receiving region of the barrel and relaxes to a generally straightened position during respective application of elevated (atmospheric) and subatmospheric pressure. This alternating pressure in the annular region effectively causes the barrel wall to massage the teat and thereby promote the extraction of milk. 
     Once the milk is effectively extracted from one or more of the teats, many automatic milking machines include an automatic take-off feature. The teatcup assembly is removed from the teat of the animal, with a beneficial effect of reducing irritation caused by vacuum and pulsation longer than is necessary to extract the milk. Once the teat cup assembly is removed from the teat, the mouth of the liner is no longer sealed around the teat and air rapidly rushes in. In consequence, a greater demand is placed on the vacuum pump in order to maintain a desired vacuum in the milking system. As multiple claws are commonly connected to a single vacuum pump, other teatcup assemblies may still require vacuum for milking, or even other assemblies attached to the same milking claw which are still connected to another teat of the same animal. 
     One problem thus encountered during milking is excessive loads placed on the vacuum pump when a teatcup is detached from a teat. As noted in U.S. Pat. No. 5,493,995, the disclosure of which is incorporated herein by reference, one solution provided to control the demands on the vacuum pump is allowing the teatcup assembly to drape over the opening in the short milk nipple of the claw. This practice substantially reduces the flow of air through the passage drawn by the vacuum pump and thereby reduces vacuum demand. However, there are several problems associated with this system. One is that chafing and cuts rapidly occur where the liner engages the short milk nipple. Once a liner is cut, it must be discarded as the leakage of air through the liner impedes proper milking. This increases costs to the dairyman both in terms of material and in labor to inspect and frequently replace liners. Another problem is that not all teat cups are the same, varying in size and weight. As a consequence, making the liner wall of the proper thickness to shut off for one teat cup may not work for a lighter teat cup which has insufficient weight to cause proper bending of the liner. A liner with one wall thickness may be too thick may prevent shut-off, while making the liner wall too thin may cut too rapidly. Furthermore, changes in environmental conditions during the year make the liner more flexible in warmer weather while more rigid in colder weather. 
     There has thus developed a need for an improved liner which addresses these problems while still reducing energy consumption by the vacuum pump and resisting cutting from the short milk nipple of the claw. 
     SUMMARY OF THE INVENTION 
     These and other problems have largely been addressed by the variable shut off teat cup liner of the present invention. That is to say, the liner provides a degree of adjustability in regard to the flexibility of the liner in a segment of the short milk tube intended for mounting in engagement with the nipple, while providing improved cut resistance in the segment. The liner is particularly useful with milking claws having short milk nipples with angled edges so that the wall of the liner lays across the nipple opening, with improved cut resistance. A single liner may be used by the dairyman with different claws and different environmental conditions by permitting the dairyman to vary the placement of the liner on the nipple and thus change the relative flexibility in the segment intended for bending over the opening of the nipple of the milking claw. 
     The liner hereof includes a mouthpiece, a barrel and a short milk tube as is conventional. However, the short milk tube includes a segment including a plurality of grooves to promote bending of the liner in this area when the teat cup liner is detached from the animal&#39;s teat. While the segment is sufficiently stiff to slightly bend but avoid folding by the weight of the liner alone, when the teat cup is attached, it bends sufficiently to drape over the opening of the nipple of the claw when properly mounted. The segment most preferably includes both a plurality of circumscribing grooves and a plurality of longitudinal grooves in the outer surface of the liner wall. The circumscribing grooves are axially spaced at different intervals whereby lugs of different widths are a part of the segment. The resulting larger lugs are preferably located more proximate the mouthpiece of the liner, while the relatively smaller lugs are thereby positioned more proximate the nipple receiving end of the liner. The resulting construction of the segment permits the user to effectively adjust the tendency of the segment to bend according to how far the short milk tube is installed over the nipple. By installing the liner on the nipple of the milk claw to a greater degree, the short milk tube tends to bend at that portion of the segment having the larger lugs and thus is relatively less flexible. If the liner is installed such that a lesser amount of the short milk tube overlies the nipple, then the short milk tube tends to bend in the region of the small lugs where the circumscribing grooves are closer together and thus is more flexible. Thus, the degree of flexibility can be readily adjusted by the dairyman by increasing or decreasing the amount of overlap of the short milk tube over the nipple. Moreover, the longitudinal grooves provide flexibility but tend to cause the lugs on the upper side of the segment to close together when the liner bends in the area of the segment. Thus, the wall thickness of the liner at the lugs having an increased thickness relative to the wall thickness of the liner at the grooves, the lugs of the liner where the greatest bending occurs move toward each other to thereby resist cuts extending through the liner along a possibly sharp edge of the nipple. 
     These and other advantages of the present invention will be readily apparent to those skilled in the art with reference to the drawing and description which follows. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a side elevational view of the variable shut off teat cup liner of the present invention with the dashed lines showing a teat cup which receives the liner therethrough; 
     FIG. 2 is a vertical cross-sectional view of the liner of FIG. 1, showing the wall thickness of the liner and the depth of the circumscribing grooves in the segment of the short milk tube intended for contacting the nipple; 
     FIG. 3 is a perspective view showing four teat cup assemblies mounted to a milking claw with the assemblies in a first upright position where an animal&#39;s teats may be received into the liners for milking; 
     FIG. 4 is a perspective view similar to FIG. 3 but showing the teat cup assemblies in a second downwardly oriented position typically occupied when the assemblies are detached from the animal&#39;s teats after milking; 
     FIG. 5 is a fragmentary side elevational view showing a teat cup assembly in the first upright position of FIG. 3 to show the bending of the short milk tube in the segment of the short milk tube; 
     FIG. 6 is a fragmentary side elevational view similar to FIG. 5 but showing a portion of the short milk tube in cross section to illustrate the position of the nipple of the claw when the teat cup assembly is in the first upright position; 
     FIG. 7 is a fragmentary bottom view showing the teat cup assembly in the second position to illustrate the closure of the circumscribing grooves between the differently sized lugs along the inside curvature as the short milk tube bends downwardly; 
     FIG. 8 is a fragmentary top plan view showing the teat cup assembly in the second position as in FIG. 7 showing the opening of the circumscribing grooves on the top or outside curvature of the bended segment of the short milk tube; 
     FIG. 9 is a fragmentary side elevational view showing the teat cup assembly in the second position as in FIG. 7, showing the circumscribing grooves opening on the top side and closing on the bottom side of the segment; and 
     FIG. 10 is a fragmentary side elevational view in partial section of the teat cup assembly in the orientation of FIG. 7 showing the engagement of the edge of the nipple with the inside of the liner wall in the segment of the short milk tube. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to the drawing, a teat cup liner  20  in accordance with the present invention includes a mouthpiece  22 , a barrel  24  and a short milk tube  26 , the short milk tube including a segment  28  constructed for engagement with an edge of a milking claw nipple and a nipple-receiving end  30 . The liner  20  is elastic and preferably molded of synthetic rubber and is intended for insertion into a teat cup  32 . The teat cup has a pulsation line connector  34  which fluidically communicates with a source of vacuum such as a vacuum pump (not shown) by a pulsation tube  36 . An annular space  38  is provided between the barrel  24  and the teat cup  32  whereby alternating pressure, such as between a vacuum and atmospheric pressure, is created in the annular space  38  during milking. The liner  20  is connected to a milking claw  40  which includes at least one and preferably a plurality of nipples  42  by sliding the nipple-receiving end  30  over the nipple  42 . The nipple may have a straight-across, circular opening as shown in U.S. Pat. No. 5,493,995, but the present invention is more particularly adapted for use with a nipple  42  having a beveled edge  44  with an upwardly-oriented opening  46  when the claw is in a normal milking position beneath the udder of the animal as illustrated by the position shown in FIGS. 3,  4 ,  6  and  10 . The liner  20  and the teat cup  32  together form a teat cup assembly  48 . 
     In greater detail, the liner mouthpiece  22  includes a circumferentially inwardly extending lip  50  which forms a mouth  52  which is sized to receive a dairy animal&#39;s teat therein and to seal around the teat during milking, but to also permit the teat cup assembly  48  to fall or be removed from the teat manually or by a take-off device once milking is completed. The mouthpiece  22  includes a skirt  54  which extends over a relative large opening  56  of the teat cup  32  to seal the annular space  38 . The liner  20  has a wall  58  with an interior surface  60  which defines a channel  62  to permit vacuum from the vacuum pump communicated through the claw and the channel  62  to extract milk from the teat and to permit the extracted milk to be pulled by the vacuum through the channel  62  and into the claw. The thickness of the wall in the region of the barrel  24  is preferably reduced relative to the thickness in the short milk tube  26  to permit the barrel to flex according to the pulsating pressure in the annular space  38 . A shoulder  64  is positioned at the normally lowermost end of the barrel  26  in order to seal around the teat cup  32 . The short milk tube  26  passes through a hole  66  in the teat cup  32  opposite the large opening  56 . The nipple-receiving end  30  is sized to seal around the nipple  42  of the claw  40  and has an open end  68  to permit passage over the nipple  42 . 
     The segment  28  adapted for engagement with the edge of the nipple is located on the short milk tube  26  between the skirt  54  and the nipple-receiving end  30 . As seen in the drawings, the wall  58  is provided with a plurality of axially spaced circumscribing grooves  70  in the outer surface  72  of the segment  28  as well as a plurality of circumferentially spaced longitudinal grooves  74  in the outer surface  72 . The longitudinal grooves are preferably evenly circumferentially spaced, for example at about 60 degrees for six grooves  74 , and extend between a first proximate circumscribing groove  70   a  more proximate the nipple-receiving end  28  and a remote circumscribing groove  70   e  relatively remote from the nipple-receiving end  28 . Intermediate circumscribing grooves  70   b ,  70   c  and  70   d  are located between grooves  70   a  and  70   e  but with progressively increasing spacing therebetween from the proximate circumscribing groove  70   a  to the remote circumscribing groove  70   e . For example, the groove-to-groove spacing between adjacent circumscribing grooves may progressively increase from about 3 arid ½ mm between grooves  70   a  and  70   b , to about 4 and ½ mm between grooves  70   b  and  70   c , to about 5 and ½ mm between grooves  70   c  and  70   d , and about 6 mm between grooves  70   d  and  70   e . The circumscribing grooves  70  and the longitudinal grooves  74  are preferably angled with a flat bottom surface in the groove  70  and have a depth of about 1 and ¼ mm. 
     The grooves  70  and  74  together define a plurality of lugs  76 . The lugs  76  thus increase the thickness of the wall  58  corresponding to the depth of the grooves, for example about 1 and ¼ mm. Similarly, the length of the lugs  76  progressively increases corresponding to the groove-to-groove spacing between the grooves  70 , such that lugs  76   a  proximate the nipple-receiving end are narrower than lugs  76   b , which are in turn narrower than lugs  76   c , with lugs  76   c  narrower than lugs  76   d  as shown in the drawings. Each of the lugs  76   a  are preferably, though not necessarily, of substantially the same dimensions, with each of the lugs  76   b  similarly of the same size relatively to one another but larger than lugs  76   a , and so on with respect to lugs  76   c  relatively to lugs  76   b  and lugs  76   d  relative to lugs  76   c . The grooves  70  and  74  are provided such that the lugs  76  have side surfaces  78  which are obliquely angled relative to the bottom surface of the grooves and the top surface of the lugs  76 . The side surfaces  78  of the lugs are most preferably angled about 18 degrees from a perpendicular line to the bottom surface of the grooves and the top surface of the lugs, so that two opposing side surfaces  78  of adjacent lugs  76  diverge at about 36 degrees relative to one another. 
     In use, the liner  20  is mounted on the teat cup  32  and the nipple-receiving end of the liner  20  is installed over the nipple  42  while the pulsation tube  36  is connected onto the pulsation line connector  34  of the teat cup  32 . Depending on the environmental conditions and the weight of the teat cup  32 , the short milk tube  26  is positioned on the nipple  42  so that the liner properly hangs from the nipple  42  as shown in FIGS. 9 and 10 when not connected to the animal&#39;s teat. When the liner  20  is properly mounted, the nipple-receiving end  30  properly seals around the nipple  42  and holds the liner  20  in place, and the upper portion  80  interior surface  60  of the liner wall  58  in the segment  28  lays across the opening  46  when the segment  28  bends under the influence of gravity when the teat cup assembly is in a second, non-milking hanging position as shown in FIG. 4 but not when the teat cup assembly is in a first, milking orientation as shown by FIG.  3 . By such positioning across the opening, during bending of the segment  28 , the upper side of the interior surface  60  of the liner wall  58  along the channel  62  corresponding to the segment  28  substantially closes against the edge  44  of the opening  46  to inhibit the passage of air therethrough. The vacuum in the channel may also act to help pull the upper portion  80  of the wall  58  against the opening and thereby aid in the sealing relationship. The edge  44  of the opening  46  may be sharp. Thus, proper positioning of the short milk tube  26  over the nipple  42  is important to both have an effective hanging relationship of the teat cup assembly from the nipple  42  to promote sealing of the nipple opening  46 , while resisting cuts and maintaining a good seal of the nipple-receiving end around the nipple. In warmer environments where the liner is more flexible as a result of the increased temperature, it may be possible to move the nipple-receiving end farther down on the nipple  42 , thereby increasing the likelihood that the edge of the nipple  42  will engage the liner wall  58  opposite a lug  76 . 
     However, in colder climates or in the case of lighter weight teat cups, it may not be possible to move the nipple-receiving end all the way down over the nipple  42  and still have the desired bending at the segment  28 . In this instance, an increase in flexibility in the segment may be achieved by having less of the nipple-receiving end  30  positioned over the nipple, thereby increasing the moment arm of the teat cup to achieve a more pronounced hanging. However, the lugs  76  may nonetheless engage the edge of the nipple  42  opening  46  as shown, for example, in FIG.  10 . 
     The longitudinal grooves  74  aid in providing flexibility of the liner to hang in the proper relationship by increasing the flexibility of the segment in combination with the circumferential grooves  70 . If circumferential grooves only, for example, were provided, the ability of the segment  28  to bend at the lugs would be limited. However, the longitudinal grooves  74  permit the lugs to be separated circumferentially and to move together along the top surface on the outside of the segment. FIGS. 7 and 8 demonstrate how the lugs  76  on the inside curvature  82  along the bottom side of the segment  28  when in a hanging orientation differ in spacing from those on the outside curvature  84  along the top side of the segment  28 . The angled sides of the longitudinally extending grooves  74  permit the lugs  76  on the top surface of the outside of the segment  28  to move together as illustrated in FIG. 8, while those on the bottom side of the segment retain their spacing as shown in FIG.  7 . This relative closure of the longitudinal grooves  74  on the outside curvature  84 , i.e. the top surface of the exterior of the segment  28  when in the hanging, non-milking orientation, not only improves flexibility to permit restriction of airflow past the nipple opening  46 , but also provides that the lugs  76  will be more continuous in a circumferential direction to protects the liner wall  58  from stressing that could promote cracks or cuts. On the other hand, the lugs  76  along the inside curvature  82 , i.e. the bottom side of the segment, move together on opposite sides of the circumscribing grooves  70  as shown in FIG. 7, the lugs ultimately contacting one another if the bending becomes too great, thereby limiting the bending to avoid localized overstressing the rubber in the segment. 
     Thus, the liner hereof provides substantial benefits in comparison to conventional liners having outwardly extending longitudinally extending splines and those with circumscribing raised ribs in the short milk tube. The lugs hereof are progressively larger due to the increasing groove-to-groove spacing, which permits the degree of flexibility of the segment to be varied by simply changing the placement of the nipple-receiving end on the nipple  42 , with the combination of the longitudinal grooves  74  and the circumscribing grooves  70  cooperating to provide flexure without permitting the segment to fully bend and thereby promote stress and cracking. Unlike in previous liners such as shown in the U.S. Pat. No. 5,493,995 patent, complete bending is not required for airflow reduction as shown by FIGS. 9 and 10, while the channel remains open during normal milking positioning as shown by FIGS. 5 and 6. Unlike the splines or circumscribing ribs of the prior art liners, the lugs on the top surface and those on the bottom side work cooperatively to permit bending to a proper degree because the grooves extend both longitudinally and circumferentially. 
     Although preferred forms of the invention have been described above, it is to be recognized that such disclosure is byway of illustration only, and should not be utilized in a limiting sense in interpreting the scope of the present invention. Obvious modifications to the exemplary embodiments, as hereinabove set forth, could be readily made by those skilled in the art without departing from the spirit of the present invention. 
     The inventors hereby state their intent to rely on the doctrine of equivalents to determine and assess the reasonably fair scope of their invention as pertains to any apparatus not materially departing from but outside the literal scope of the invention as set out in the following claims.