GB2257612A

GB2257612A - Milking machine clawpiece

Info

Publication number: GB2257612A
Application number: GB9115610A
Authority: GB
Inventors: Tony Kenneth Griffin
Original assignee: National Research Development Corp UK
Current assignee: National Research Development Corp UK
Priority date: 1991-07-19
Filing date: 1991-07-19
Publication date: 1993-01-20
Also published as: GB2273640B; NZ243529A; EP0597901A1; CA2110507A1; GB9324109D0; WO1993001709A1; GB2273640A; GB9115610D0

Abstract

A milking clawpiece (12) in which the pulsation distribution chamber (40) is evacuated and the liner opens so that milk flows as far as the (closed) clawpiece valves (52). whereas when the pulsation chamber is at atmospheric pressure, the liner closes and the clawpiece valve opens to allow the short milk tubes to discharge their contents via the clawpiece cavity (42) into the long milk tube. <IMAGE>

Description

MILKING MACHINE CLAMPIECE The present invention relates to a milking machine clawpiece for use in automatic milking apparatus.

The basic components of a milking installation, at least as far as the present invention is concerned, are (1) a cluster of four teat cups including (2) a clawpiece, (3) a suction pump and (4) a pulsator. Each teat cup contains an annular pulsation chamber defined between a rigid outer casing of the cup and a flexible inner liner which fits over one of the cow's teats.

In use, a steady pressure of approximately 50 kPa below atmosphere is continuously applied to the "core" space enclosed by the liner. Apart from encouraging a flow of milk into the core space, this negative pressure is also effective to clamp the teat liner on to the teat - this being referred to as "adhesion".

The pressure applied by the pulsator to the annular pulsation chamber, however, alternates between a first pulsation value of 50 kPa below atmospheric pressure and a second pulsation value of atmospheric pressure.

At the first pulsation value, there is zero differential across the liner, and milk is sucked from the teat into the core space. From the core space the milk is drawn down a flexible "short milk" tube into one of the four tubular inlet "nipples" projecting upwardly from the interior volume of a special junction called a "clawpiece". From the clawpiece the milk is drawn through an outlet nipple and via a "long milk" tube to an appropriate receptacle or pipeline. The other three nipples of the clawpiece are connected to similar teat cups and thence to the other teats of the cow's udder.

At the second pulsation value, the liner collapses on the teat and the pressure applied by it to the teat causes cessation of milk flow and provides a necessary massage of the teat.

During normal operation, the pulsation pressure switches from one value to the other, with a cycle frequency which is typically -once every second, giving rise to a correspondingly intermittent flow of milk.

According to a first aspect of the present invention, a milking machine clawpiece comprises a pulsation distribution chamber which is isolated from the milk-carrying cavity of the clawpiece by the diaphragm or like-operating device of a valve assembly for the clawpiece inlet nipples whereby, in operation, when the pulsation distribution chamber is evacuated to open the liners and allow milk to flow from the teats into the short milk tubes, the pressure difference across the diaphragm or like-operating device holds the valve assembly in a first position to close the clawpiece valves when the pressure in the clawpiece cavity exceeds that in the associated inlet nipples and milk from the teats flows only as far as the closed clawpiece valves, whereas when the pulsation distribution chamber is at atmospheric pressure to close the liners and prevent milk flow from the teats, the pressure difference across the diaphragm or like-operating device holds the valve assembly in a second position to open the clawpiece valves and allow milk previously collected in the short milk tubes upstream of the closed clawpiece valves to discharge into the clawpiece cavity for removal via the clawpiece outlet nipple into the long milk tube.

The term "like-operating device" is to be interpreted as including any means (other than a diaphragm) which is responsive to a pressure differential between the clawpiece pulsation distribution chamber and cavity, to move the valve assembly between first and second valve operating positions as above described. One such means would comprise a piston, for example.

Conveniently, the valve assembly is vertically displaceable between an upper first position and a lower second position.

Conveniently, the valve assembly includes an external part by means of which the valve assembly can be moved to close the clawpiece valves irrespective of the operating conditions within the clawpiece. Such movement might be effected manually, for example, or by a conventional automatic cluster removal attachment.

Alternatively (or additionally), the clawpiece includes an external part which can be moved to shut off the normal supply route of pulsating vacuum supply to the pulsation distribution chamber and control means are provided to control an alternative supply route for the pulsating vacuum supply so as to isolate the pulsation distribution chamber from the atmospheric pressure component of this supply. As before, the required movement of the external part may be effected manually, for example, or by a conventional automatic cluster removal attachment.

Conveniently, the clawpiece valves have at least a degree of independence from one another so that, when the valve assembly is in the first position, one or more of the valves can open in response to an appropriate pressure differential across the valve or valves while the remaining valves or valve remain closed.

Thus in one such case, the valve assembly is made of rubber or other resilient material and comprises an upper diaphragm portion which is linked by a stem to a depending skirt portion divided into four separate flap sections serving as the individual clawpiece valves.

According to a second aspect, the invention comprises a valve assembly as described in the preceding paragraph.

According to a third aspect, the invention comprises a milking installation including one or more clawpieces according to the first aspect of the invention.

In conventional milking machines, as used for the last sixty years or so, a small air bleed is provided in the clawpiece or in the short milk tubes to assist the transport of milk from the milking cluster to the receptacle or pipeline. This first method of milking is referred to as conventional milking.

More recently, it has been proposed to control udder disease by using one-way valves within the liner, within the short milk tubes or within the clawpiece to prevent flow back of milk towards the teat. When operated without airbleeds, the teat liners in such cases are substantially sealed, during milking, from any supply of air to the milk-carrying core regions of the teat liners. Teat liners sealed in this way are referred to as pneumatically-isolated teat liners and the new second method of milking produced, which has certaln performance advantages over conventional milking, is referred to as hydraulic milking.

UKPA 90 12325.8 (National Research Development Corporation) proposes a method of automatic milking in which, during the main milking period, the teat liners are substantially sealed from any supply of air to the milk-carrying core regions of the teat liners whereas during the closing stages of milking, air is automatically admitted to said regions to provide conventional milking. This third method of milking is referred to as dual regime milking.

The clawpiece of the present invention has application in all three methods of milking outlined above but it is possibly at its most advantageous when used in a dual regime system.

An embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 shows a simplified and somewhat diagrammatic view of part of a typical milking installation utilising clawpieces according to the present invention; Figure 2 shows a somewhat diagrammatic vertical section of a clawpiece for use in the installation of Figure 1; Figure 3 shows the same clawpiece as Figure 2 at a different stage of its operation; Figures 4a and 4b (collectively referred as Figure 4) respectively show a cross-section and perspective view of a valve assembly for use in the clawpiece of Figures 2 and 3; and Figure 5 shows a modification of the clawpiece of Figures 2 and 3.

The same reference numerals have been used for the same or functionally similar items in the different Figures.

Thus referring first to Figure 1, this Figure shows, by way of illustration, only two milking units 8 although in practice there will typically be ten or so such units in an average-sized milking installation.

Each unit 8 consists basically of four teat cups 10, a clawpiece 12, four short milk tubes 14 connecting the teat cups to the clawpiece, and a long milk tube 16 taking the milk from the clawpiece to a recorder jar 18 (or other milk measuring device).

Milk flow away from the teats, but not in the reverse direction, is allowed by one-way milk flow valves (not shown).

In hydraulic and dual regime milking systems, the conventional air-bleeds upstream of these one-way milk flow valves are omitted so that during normal operation, the installation will provide hydraulic milking. For further details of specific examples of these valves, and of hydraulic and dual regime milking in general, reference should be made to British Patent No. 2159685 B (National Research Development Corporation) and UKPA 90 12325.8 (National Research Development Corporation).

For details of a particularly advantageous design of conventional milking assembly, reference may also be made to UKPA 90 20952.9 (National Research Development Corporation).

Returning now to Figure 1, it will be seen that the bottoms of the recorder jars 18 are connected to a common milk conveyance pipeline 20 although in an alternative embodiment (not shown), the jars 18 (or equivalent) are omitted and the long milk tubes 16 lead directly to the common milk conveyance pipeline 20.

Reference numeral 22 indicates the milking vacuum pipeline while reference numeral 24 indicates the air line for the pulsator 26.

As shown, the common milk conveyance pipeline 20 leads to a receiver vessel 28 and in operation of the installation, a milk pump 30 operates to discharge milk from the vessel 28, via pipeline 32, to a bulk tank (not shown).

The installation further includes the usual sanitary trap 34, vacuum regulator 35, interceptor 36 and vacuum pump 37.

Turning now to Figure 2, this shows one of the clawpieces 12 for use in the milking installation of Figure 1.

The clawplece comprises a pulsation distribution chamber 40 which is isolated from the milk-carrying cavity 42 of the clawpiece by the diaphragm portion 44 of a vertically displaceable valve assembly 46 for the four clawpiece inlet nipples 48. Reference numeral 49 indicates the usual pulsating vacuum supply inlet to chamber 40.

The assembly 46 (see also Figure 4) is made of rubber, or other resilient material, and comprises a depending skirt portion joined to the diaphragm portion by a stem 50. The skirt portion is divided into four separate flap sections 52 serving as the individual clawpiece valves, each of which is able to remain closed independently of the others in the event that a continuous vacuum is present in the associated inlet nipple 48 e.g. due to the cessation of milk flow from the relevant teat.

As shown in Figure 2, the upward travel of the diaphragm portion 44 is limited by downwardly projecting stop portions 54 which surround an externally projecting pull 56. An upward movement of the pull will raise the assembly 46 to close the valves, whatever the operational conditions, within the clawpiece. Pull 56 may be displaced manually or by a conventional automatic cluster removal attachment at the end of milking.

Figure 5 shows an alternative arrangement in which the pull (58) operates instead to shut off the normal pulsating vacuum supply route to the chamber 40 which is thereafter isolated from the atmospheric pressure component of this supply by a one-way valve 59.

In another alternative arrangement (not shown), the shut-off arrangements of Figures 2 and 5 are combined so that lifting the pull both closes the clawpiece valves 52 and shuts off the normal vacuum supply route to chamber 40 which continues to be evacuated via the one-way valve 59.

Instead, or (in the case of the two alternative arrangements described above) additionally, the vacuum supply to the milking units 8 can be shut off at the end of milking by any convenient means e.g. a conventional shut off valve located in the long milk tube to the unit or between the vacuum supply tube 22 and the associated recorder jar 18 for the unit.

Figure 2 illustrates the valve assembly 46 as it will appear when chamber 40 is evacuated and the valves 52 close to prevent the flow of milk from the short milk tubes (via nipples 48) into the cavity 42 whenever the pressure in the clawpiece cavity exceeds that in the associated inlet nipples. Figure 3, on the other hand, illustrates the situation where the pulsation distribution chamber is at atmospheric pressure and the assembly 46 has been displaced downwardly to open the valves 52 and allow milk to flow into cavity 42 for passage, via outlet nipple 60, into the long milk tube.

Pulsating the liner on the teat provides necessary massage to encourage blood circulation in the teat and avoid damage to the teat tissue. Pulsation also provides relief for the musculative tissue surrounding the teat orifice necessary to maintain the integrity of the streak canal and its function of preventing invasion by pathogenic organisms. Malfunction of pulsation to the teat is known to cause teat end damage and increased pathogenic penetration into the udder.

Nevertheless, in conventional milking clusters, pulsation also disturbs the flow of milk from the teat cups and can cause impacts on the teat end which aid penetration of pathogen through the streak canal and into the udder.

Pathogenic invasion through the streak canal of the teat invariably results in disease (commonly called mastitis).

In a fourth aspect, the present invention relates to a method of milking which combines the use of valves which control milk flow in the clawpiece of the milking machine cluster and air flow into the mouthpiece of the teat cup liner, and themselves are controlled by the pulsation system of the milking cluster.

Pulsation controlled air flow valves for the mouthpiece are the subject of previous patent applications No. GB 90 12325.8 and GB 90 20952.9.

According to this fourth aspect, the present invention is a milking method which uses this type of air flow valve in combination with a new mechanism controlled by pulsation and organises the direction of milk flow from the teat cups into the clawpiece chamber.

Typically, when used in conjunction with the systems of GB 90 12325.8 and GB 90 20952.9, the new method of milking functions as now described. When vacuum is applied to the outside of the liner, it also closes the air valve at the mouthpiece of the liner and the valves between the teat cup and the clawpiece. When the milking cluster is first applied, teat barrel adhesion is established and then the air valve only serves to maintain the mouthpiece pressure at atmosphere each time atmosphere is applied to the pulsation chamber. It continues this function until the late stages of milking when teat barrel friction is lost with the liner, and air drives out the milk in the teat cup each time the liner is collapsed and the pulsation chamber is at atmosphere.During the whole of milking, however, the milk valves are opening and closing (in sympathy with pulsation pressure), being closed whilst the liner is opening and being open when the liner is in the closed position. Milk only flows past them if the clawpiece pressure is lower than that in the teat cup. When the pulsation pressure changes to atmosphere, the milk valves open while the liner collapses and expels the milk collected during the liner open phase (vacuum phase). By these means milk is encouraged to flow only in one direction away from the teat thus avoiding the problems caused by multidirectional milk flow in the conventional milking machines.

Machine induced infection is controlled and the milk receives less damage during transport (less lipolysis) in the machine.

Any earlier milking method can be compared to the new method in the following way. Basically the hydraulic milking method used only milk flow valves with no air admission. In hydraulic milking the gravity-closed valves operate independently of pulsation and respond only to the changes of pressure of the teat cup in relation to pressure in the clawpiece. At the end of milking a special arrangement is made to introduce air into each mouthpiece simultaneously to unclamp the teats from the liner.

The main physical disadvantages of hydraulic milking are 1) mouthpiece vacuum can be uncomfortably high and 2) the independent valves can, especially in low or air flow periods of milking, collapse the liner tightly on the teat end without relief.

The present invention according to said fourth aspect as above discussed, is designed to overcome these particular disadvantages so that the beneficial aspects of controlled flow can be achieved without detriment.

Claims

1. A milking machine clawpiece comprising a pulsation distribution chamber which is isolated from the milk-carrying cavity of the clawpiece by the diaphragm or like-operating device of a valve assembly for the clawpiece inlet nipples, whereby, in operation, when the pulsation distribution chamber is evacuated to open the liners and allow milk to flow from the teats into the short milk tubes, the pressure difference across the diaphragm or like-operating device holds the valve assembly in a first position to close the clawpiece valves when the pressure in the clawpiece cavity exceeds that in the associated inlet nipples and milk from the teats flows only as far as the closed clawpiece valves, whereas when the pulsation distribution chamber is at atmospheric pressure to close the liners and prevent milk flow from the teats, the pressure difference across the diaphragm or like-operating device holds the valve assembly in a second position to open the clawpiece valves and allow milk previously collected in the short milk tubes upstream of the closed clawpiece valves to discharge into the clawpiece cavity for removal via the clawpiece outlet nipple into the long milk tube.

2. A milking machine clawpiece as claimed in Claim 1 in which the valve assembly is vertically displaceable between an upper first position and a lower second position.

3. A milking machine clawpiece as claimed in Claim 1 or Claim 2 in which the valve assembly includes an external part by means of which the valve assembly can be moved to close the clawpiece valves irrespective of the operating conditions within the clawpiece.

4. A milking machine clawpiece as claimed in any preceding claim including an external part which can be moved to shut off the normal supply route of pulsating vacuum supply to the pulsation distribution chamber, and control means adapted to control an alternative supply route for the pulsating vacuum supply so as to -isolate the pulsation distribution chamber from the atmospheric pressure component of this supply.

5. A milking machine clawpiece as claimed in Claim 4 in which the clawpiece valves have at least a degree of independence from one another so that, when the valve assembly is in its first position, one or more of the valves can open in response to an appropriate pressure differential across the valve or valves, while the remaining valves or valve remain closed.

6. A milking machine clawpiece as claimed in Claim 5 in which the valve assembly is made of rubber or other resilient material and comprising an upper diaphragm portion which is linked by a stem to a depending skirt portion divided into four separate flap sections serving as the individual clawpiece valves.

7. A valve assembly made of rubber or other resilient material and comprising an upper diaphragm portion which is linked by a stem to a depending skirt portion divided into four separate flap sections serving as the individual clawpiece valves.

8. A milking installation including one or more clawpieces according to Claims 1 to 7.

9. A milking machine clawpiece, valve assembly or milking installation substantially as hereinbefore described with reference to, and/or as illustrated in, the accompanying drawings.