GB2191076A - Milking machine claw - Google Patents

Abstract

A milking machine claw (10) having obstruction free vacuum characteristics which is easy to clean. A single large vacuum chamber (13) is provided with radially disposed valve chambers (18) to eliminate restrictive and unhygienic ducts. <IMAGE>

Description

SPECIFICATION Milking machine claw The present invention relates to an improved claw for milking machines, particularly of the type having vulvular means for automaticaliy closing off vacuum to teat cups during the putting on, removal or dropping of the cups from the teats of the cow. Such milking machine claws prevent a vacuum drop in the system caused by air rushing through the open teat cups.

Milking machine claws ofthis generaltype have been known for many years past and ofthese, Australian Specification Nos. 22173/56 and 51946/59 are representative examples. Typicallythese claws consist of a block like cylindrical body having a flat machined upperface over which is placed a rubber gasket and a cover which has a connection to a source of pulsation, these parts being attached to the body by a screw threaded stud which receives a readily removable clamping nut. Bored in the bodies and extending inwardlyfrom the flat upperface are valve chambers which house ball or othertype valves.These valve elements are adapted to traverse the respective milk flow passages in the claw body in circumstances when a rush of air, indicative of removal of a teat cup, occurs thereth rough. In operation a leak path is provided to allow a small quantityofairto be withdrawn via theteatcup throughtheclawtothevacuum lineeven after closing of the valve. This leakage enables, when the teat cups are applied, a vacuum to be produced inside each teat cup whereby suctional forces holding the valve element in a closed position is equalised to allowthe valve elements to drop back into a withdrawn normal operational position.

Formed diametrically in a plane at rig ht-angles to the valve chambers is a central passage forming a vacuum chamberwhich is connected internally by radial ducts to the valve chambers and externally to a milkdropperwhich in turn is connected to the vacuum pertaining in the milk line ofthe milking system. Ducts are also formed in the body opposite the valve seats and these connect the valve chambers to radial connections on the body which are in turn connected to the teat cups to receive the milktherefrom. These claws suffer from a numberof disabilities which affect their efficiency in practical operation. The above mentioned central passage or vacuum cavityforms a serious disability and particularly so where the valve chambers are so placed and connected to the central passage.

During milkflowthe limited central passage together with the turbulence occasioned by the opposing streams of milk entering it from the teat cups via the internal ducts creates a restriction to the flow out-going to the milk line and so also, an impedimenttothe rate of milking. Of importance also istheflow/back of milkfrom the milkdropper into the central passage immediately the vacuum pulse to cups takes place. This flow back into such a congested area impedes that direct and rapid vacuum pulse to the teat cups so necessary to both preventcupfalling and to ensure that rapid milking so essential to efficient production.

The importance ofthis obstructive effect can be readily understood when it is considered thatthe complete vac/air pulse to cups takes place in 1 to 1.1 seconds and that the actual vacuum ormilking pulse lasts only .5 to .6 of one second.

In regard to hygiene, the internal passages ofthese claws are difficult to maintain in that essentially clean condition so necessaryforthesafe handling of milk. The object of the present invention is to correct the faults or disadvantages common to claws of the aforementioned type.

Accordingly, the present invention provides a milking machine claw comprising a housing defining a vacuum chamber, wall means surrounding said chamber, outlet means from said chamber leading through said wall means and adaptedforconnectiontoa a milk line of a milking machinesystem, inlet meansto said chamber leading through said wall means adapted for connection to at least one teat cup, and valve means adapted to at least substantially close said inlet means upon removal of the or any one said teat cup.

Conveniently said inlet means comprises individual passages, each adapted for connection to a separate teat cup and said valve means is provided in said individual passages outwardly of said wall means.

By providing an arrangement as indicated above, there is achieved a unit witch obstruction free vacuum characteristics which allows milkflow in a direct line from teat cups to milk line. Bythesubstitution of a single largevacuum chamberorcavitytogetherwith the external radial disposition ofvalve chambers all restrictive and unhygienic ducts and passages have been eliminated and its volume or capacity is such that the obstructive effect of back flow of milk into the claw from its dropper connection to the milk line is completely negated. Sharp and constant milking orvacuum pulses to the teat cups are thus ensured at all times.

Further preferred features and aspects ofthe present invention will become appa rent from the following description of one preferred embodiment illustrated in the accompanying drawings, in which: Figure 1 is a perspective view of the preferred milking machine claw according to the present invention; Figure2 is a top plan view of the milking machine claw configuration shown generally in figure 1; Figure 3 is a side elevation view of the claw shown infigure 2 looking in the direction ofarrowXofthat figure; Figure 4 is a sectional view taken along line A-A of figure2; Figures a sectional view taken along line C-C of figure4; Figure 6 is a sectional view taken along line B-B of figure 4;; Figure 7 is a sectional view taken along line D-D of figure 6; Figures 8 and 9 are respectively plain and side elevation views of a second preferred embodiment of the present invention; and Figure 10 is a general section view taken more or less along line E-E offigure 8.

The milking machine claw illustrated in the drawings comprises a claw body 10 having a generally annularwall 11 and a closed end wall 12 surrounding a generally cylindrical vacuum chamber 13. The chamber 13 has an open face 14 closed during normal operation by an elastomeric material cap or plug 15. The plug or cap 15 may be readilyremovableto provide easy access to the interior of the claw construction for cleaning purposes.

Arranged equaliy spaced around the chamber 13 are outwardly extending lugs 16, that is generally outward ofthe annularwall 11 The lugs 16 carry both inlet passages 17 generally extending transversely through the lugs into the chamber 13, and valve chambers 18 generally extending across the inlet passages 17. The valve chambers 18 are conveniently closed by screw plugs 19. As in the prior art, a valve element 20 (ball in the illustrated embodiment) is located in the chamber and at rest (or during normal milking operation)thevalve element 20 is located generally below the inlet passage 17.When there is a rush of airthrough the inlet passage 17 indicative of a teat cup being removed from a teat, the valve element 20 is immediately drawn to the position shown in dotted outline 21 to close the iniet passage. A notch or any other similar leakage path might be provided to allow passage of a small quantity of air passed the valve element 20 when located at position 21 forthe reasons previously claimed. Certain shapes of valve elements such as cylinders do not fully seat overthe inlet passage 17 and may therefore, by their own shape, allow satisfactory leakage past the valve element 20.

As will be apparent from the drawings nozzle connectors 22 are provided leading through the annularwall 11 with a hose connection nozzle 25 for connectingthevacuumchamberl3tothemilkline of a milking machine system.

The drawings also illustrate a distribution arrangementfor distributing vacuum/air pulses two the teat cups. The distribution arrangement may comprise a series of passages located in the end wall 12 ofthe claw. An inlet nozzle 26 is provided for connection to a pulsator unit (not shown) via hose 27. The nozzle 26 leads to a central distribution passage 28 within thewall 12 and leading from this passage are outlet passages 29 with connection nozzles 32 adapted to connect two hoses 30 leading to the teat cups (not shown). In this way air/vacuum pulsations are supplied to the teat cups to cyclically inflate and deflate the teat cups to draw milk from the teats of a cow to which the teat cups are fitted.The milk thugs drawn passes during normal operation through hoses 23 to the chamber 13 and outvia nozzle connection 25 via hose 31 to the milk line (not shown). When a teat cup is removed the appropriate valve element 20 acts to close substantially, although not completely, the inlet passages 17.

Figures 8,9 and 10 show a second embodimentof the present invention wherein like features have been identified bythesame reference numerals.

Certain problems may arise with both ball and sleeve valves as currently used. As described earlier ball valvetype may have its seat notchedto providethe required Ieaktovacuum, however, the constant hammering ofthe ball on itsseatinusehastheeffect of gradually closing such notches until the leaks in each chamber are so reduced that operation of the claw becomes erratic and then eventually inoperable. Sleevetypevalves operate satisfactorily while vacuum is constant. However, during those times when vacuum drops occur, the sleeve does not rise far enough to coverthe seat and will remain so irrespective of any rise in vacuum.The result is that air rushing from the cups through the partly open valve seats can cause such a lowering ofvacuum that the cups may fall from the teats of cows being milked. Moreover, milk residues in valve chambers can also preventthe valves from completely dropping with the result that cows can be incompletely milked in one or more quarters. Figures 8,9 and 10 provide an embodiment which largely avoids these difficulties.

As shown in Figures 8,9 and lOtheclaw lOis formed in two body parts 11 and 12 which are separated by an elastomeric or rubber gasket 40 and are releasably connected together by an upstanding stud 41, a screwable nut 42 and a seal element 46. A mounting hook 43 may also be fixed to the body part 12. In this embodiment the internal distribution passages 28 of the previous embodiments are replaced by a central large distribution chamber47 within the body part 12 opening on to its lower surface adjacent the gasket 40. Located in the upper surface of the body part 11 are shallow channels 44 leading from the valve chambers 18 inwardly towards a central axis of the claw. Communication holes 45 are then dry idled downwardly through the channels 44to establish a predetermined (calibrated) size of communication between the central vacuum chamber 13 and each ofthe valve chambers 18. In this manner, a calibrated leakage path is established which is unaffected by operation ofthevalve element 20 and which remains effective during continued operation of the claw. Moreover a very open structure is achieved which is easily cleaned and sterilised when necessary.

Claims (6)

1. A milking machine claw comprising a housing defining a vacuum chamber, wall means surrounding said chamber, outlet means from said chamber leading through said wall means and adaptedforconnectionto a milklineofa milking machine system, inlet means to said chamber leading through said wall means adapted for connection to at least one teat cap, and valve means adapted to at least sustantially close said inlet means upon removal of the or any one said teat cup.

2. A milking machine claw according to claim 1 wherein said inlet means comprises a plurality of individual passages, each of said individual passages being adapted for connection to a separate said teat cup, said valve means comprising individual valve members located adjacent said individual passages outwardly of said vacuum chamber.

3. A milking machine claw according to claim 1 or claim 2wherein said housing is generally cup shaped with a first end wall and a peripheral wall surrounding said vacuum chamber, said vacuum chamber being closed by a removable second end wall opposite said firstendwalltherebyenabling easy access to internal regions of the claw for cleaning purposes.

4. A milking machine claw according to claim 3 wherein said first end wall includes distribution means for distributing vacuum/air pulses to said teat cups.

5. A milking machine claw according to claim 1 wherein each said valve means comprises a valve chamber located externally of said vacuum chamber and a valve element movable in each said valve chamber, said inlet means comprising flow passages leading from said vacuum chamberto said valve chambers and said valve elements being arranged to engage a valve seat in said valve chambers to close a said flow passage orto move therefrom to open a said flow passage, and a leakage path leading from the vacuum chamberto each said valve chamber at a distance from each said valve seat.

6. Amilking machine claw substantially as described herein with reference to the accompanying drawings.