WO2001043535A1

WO2001043535A1 - A method for cooling milk and a milking arrangement with cooling means

Info

Publication number: WO2001043535A1
Application number: PCT/SE2000/002516
Authority: WO
Inventors: Ole Lind; Gösta Andersson
Original assignee: Delaval Holding Ab
Priority date: 1999-12-16
Filing date: 2000-12-13
Publication date: 2001-06-21
Also published as: SE9904647D0; AU2416401A

Abstract

A method and a milking arrangement adapted for cooling, during ongoing milking of e.g. a cow, milk extracted from the animal being milked by a quarter milking arrange-ment (10) comprising four teat cups (11) and a tubing system (12,13,14) conveying the milk from the teat cups to a first common, downstream milk tank (15) collecting the individual milk flows from the teat cups. A pre-cooling of the milk from the teat cups is performed either in a region (A,B,C,D) of the tubing system upstream of the first common milk-collecting tank (15), or alternatively downstream of the common collecting tank in a region (E) of a milk discharge tube (19) used for draining off the milk from the tank. For this purpose a pre-cooling means is connected to and co-operates with the tubing system within a region (A,B,C,D) thereof between the teat cups (11) and the first milk tank (15) or, alternatively, is connected to and co-operates with the milk discharge tube (19) in a region (E) thereof situated directly downstream of the first milk tank.

Description

A METHOD FOR COOLING MILK AND A MILKING ARRANGEMENT WITH COOLING MEANS

TECHNICAL FIELD OF THE INVENTION

The present invention relates on one hand to a milk cooling method of the type defined in the preamble of claim 1, and on the other hand to a milking arrangement of the type defined in the preamble of claim 9.

BACKGROUND OF THE INVENTION

An automatic milking system (AMS) is a system that allows dairy cows to be milked voluntarily or on demand with little or no human interaction. In the milking machine part of an AMS the milking and monitoring of milk parameters is carried out per individual quarter of the milked cow's udder. For each quarter there is a separate teat cup, a milk and an air tube. The milk flows from the four teat cups are kept separate until they are mixed in a receiver unit normally in the form of a common collecting tank or a common milk meter.

Bacterial growth in milk is exponential. Also when then milk is stored at a low temperature, such as 6 - 8°C, the bacterial growth is not completely inhibited. To secure a satisfactory milk quality the milk should be cooled down to 4°C within 2-3 hours after having been milked.

A primary cooling might be required inter alia to avoid the blend temperature of the milk in a bulk tank exceeding a certain maximum.

A cooling of the milk shortly after its extraction is also important for minimising the lipolytic activity. A more frequent milking with varying milking intervals - as is the case with cows milked in an AMS - gives rise to increased lipolytic activity. Thus, cooling of the milk at an earlier stage than in the refrigerated bulk tank appears appropriate.

One problem with an AMS may be that a relatively small amount of milk will flow more or less continuously to the bulk tank. In particular during the night there might be periods of considerable duration with no or only a low flow of milk because of a low activity of the cows for milking. In particular, installations with long milk delivery lines for the milk from the teat cups or claw to the bulk tank, the bacterial growth could be considerable if the temperature of the milk is not reduced shortly after extraction.

To sum up, in order to secure an acceptable milk quality it is very important that the milk is cooled down as soon as possible in a quarter milking arrangement, in particular when the cows are voluntarily milked.

OBJECT OF THE DSTvΕNTION

A first object of the invention is to mώimise the bacterial growth and contents of free fatty acids (FFA) in milk extracted from a milkable animal, such as a cow, being milked by means of a quarter milking arrangement. A second object is to prevent teat- warm (lukewarm) milk from becoming stagnant or flowing too slowly in a long conveying pipe leading from a milking robot to the milk room where the refrigerated bulk tank is placed. A third object is to perform a pre-cooling by means of a heat exchanger (= cooler) wherein the channels or tubes in which the milk to be cooled passes through the cooler can easily be kept clean by flushing.

SUMMARY OF THE INVENTION

The objects of the invention are achieved by utilizing the cooling method defined in claim 1, and by means of the quarter milking arrangement defined in claim 9. Elabo- rating steps and features of the invention are defined in the method claims 2-8 and arrangement claims 10-14.

The method of the invention is characterised in that the milk, which has been extracted by the teat cups, is pre-cooled in a region of the tubing system (conveying the milk from the teat cups to a first common milk collecting tank) upstream of the common collecting tank, or alternatively, directly downstream of the collecting tank in a region of a milk discharge tube used for draining off the milk from the collecting tank. Thus, the basic idea is to perform the pre-cooling action at a short distance down- stream of the teat cups.

Preferably, a milk flow meter assembly is included in the tubing system between the teat cups and the common collecting tank In such case the pre-cooling may be carried out according to claim 2 or 3.

Suitably, the pre-cooling may take place in a set of parallel straight milk tube lengths through which the milk flows from the teat cups are passed. This action can be carried out according to claim 4. Alternatively the pre-cooling may be performed using coiled tube lengths for passing the individual milk flows from the teats through a common cooling chamber, as specified in claim 5. The cooling of the outsides of the milk conveying tube lengths passing through such cooling chamber may be performed using a gas or a liquid as the coolant fed through the chamber.

The cooling method according to the invention is suitably applied in an automatic milking system, preferably a system for voluntary milking. In such system a milking robot is used for handling the teat cups (i.e. attaching the detaching the teat cups).

The quarter milking arrangement of the invention is characterised in that a pre-cooling means is connected to and co-operates with the tubing system within a region thereof between the teat cups and the first common milk collecting tank or, alternatively, is connected to and co-operates with a milk discharge tube (draining off the milk from the tank) in a region thereof situated directly downstream of the tank.

Hereby is achieved that the milk cooling action will take place almost immediately after extraction.

The pre-cooling means preferably comprises a recuperative heat exchanger arranged as specified in claim 10.

As specified in claim 11 a common milk flow meter may be installed between the teat cups and the first common milk-collecting tank. Furthermore, the tubing system pre- ferbly comprises an individual milk tube leading from each teat cup, and an individual milk flow meter in each individual milk tube.

The pre-cooling means may be a heat exchanger as specified in claim 13 or claim 14.

When the pre-cooling means (cooler) is a plate type heat exchanger the coolant (cooling fluid) may e.g. be ice water, and the milk (which is to be cooled) is preferably fed through the cooler in counterflow (to the coolant) by a pump.

A pipe passing the milk through the cooler may be a straight or a helical tube being surrounded by the flowing, passing coolant.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described and elucidated below by means of examples of preferred embodiments illustrated on the enclosed schematic drawings.

On the enclosed drawings: Fig. 1 shows a schematic representation of essential parts of an embodiment of a quarter milking arrangement according to the invention;

Fig. 2 shows in perspective view a vacuum operated pre-cooling heat exchanger for the milk tubes from four teat cups; Fig. 3 shows an exploded view of the heat exchanger (cooler) shown in Fig. 2; Fig. 4 shows the same general type of milking arrangement as shown in Fig. 1, however with a compressor operated pre-cooling heat exchanger located in region A; Fig. 5 shows in perspective view a pre-cooling flange-plate type heat exchanger and the cooling unit thereof; and Fig. 6 shows the compressor operated heat exchnger of Fig. 4 on an enlarged scale.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Fig. 1 shows a quarter nnlking arrangement 10 which is designed for an automatic milking system (AMS). The arrangement comprises four teat cups 11 attachable to the teats of an animal, such as a cow, to be milked. In an AMS a milking robot (not shown) is used for h-mdling (attaching and removing) the teat cups. The arrangement also comprises a tubing system 12, 13,14 conveying the milk from the four teat cups 11 to a common, first milk tank 15, wherein the milk flows from the teat cups are collect- ed. A milk flow meter assembly 16 is included in the tubing system and connected between the parts 12 and 13 thereof.

Each of the tubing system parts 12 and 13 consists of four individual milk tubes 12a, 12b,12c,12d and 13a, 13b, 13c, 13d, respectively. The milk flow meter assembly 16 comprises four individual milk meters 16a, 16b, 16c, 16d, one for the milk flow from each teat cup. In each teat cup tube 12a, 12b etc. there is also a valve 17a, 17b etc. The downstream ends of the milk tubes 13a-13d are connected to a common milk meter 18 adapted to measure the total milk flow from the four teat cups 11. The milk from the milk meter 18 is conducted to the milk tank 15 by a single tube 14. From the bottom of the milk-collecting tank 15 the milk is pumped away, through a milk dis-charge tube 19, to an ordinary refrigerated bulk tank (not shown). To provide a required pre-cooling of the milk from the teat cups 11 before the milk reaches the refrigerated bulk tank, the quarter milking arrangement 10 is provided with a pre-cooling means, i.e. a heat exchanger apparatus, connected to and co-operating either with the tubing system 12, 13, 14 in a region between the teat cups 11 and milk- collecting tank 15, or with the milk discharge tube 19 in a region thereof adjacent to the tank 15. In Fig. 1 there are shown five suitable regions, designated A, B, C, D and E, for locating such pre-cooling means. Thus, the pre-cooling can be carried out either upstream of the flow meter assembly 16 (in region A or B), or downstream thereof, ahead of the common milk meter 18 (i.e. in region C). However, it is also possible to perform the pre-cooling by means of a pre-cooler (heat exchanger) connected between (i.e. in region D) the milk meter 18 and milk-collecting tank 15, or even immediately downstream of the tank 15 (i.e. in region E).

It is to be noted that in the milking arrangement 10 described above only those com- ponents and details which are essential for the understanding of the invention have been shown, and many other components and parts, e.g. pulsator and pulse tubes, included in an AMS VMS, have been omitted for the simplicity of the description and drawings.

Reference will now be made to some examples (shown in Figs 2-6) of pre-cooling apparatus suitable for the milking arrangement 10 shown in Fig. 1.

In Figs 2 and 3 there is shown a vacuum-powered pre-cooler 20 comprising a box- shaped housing 21 having an inlet 22 for cooling air and an air outlet 23 connected to a vacuum source (not shown). The housing 21 comprises a channel-shaped wall member 24 and a front wall member 25. At the opposite ends of the housing there are inserted sealing end wall members 26 and 27 consisting of three parts 26a,26b,26c and 27a,27b,27c, respectively. Four straight milk tubes 28,29,30,31 (conveying milk from four teat cups 11) extend in parallel to each other through the interior (cooling chamber) of the housing 21 and through four holes 32 in the end wall members 26,27. In Figs 4 and 6 there is shown (in an exploded view) a compressor powered pre-cooler 33 comprising two cooling panels 34 and 35 each having a fluid inlet 36 and a fluid outlet 37 for a coolant In this case the four straight milk tubes 28,29,30,31 are arranged in a common plane between the panels 34,35 and placed in parallel groves 38 and 39 on the insides of the panels. This type of pre-cooler makes possible a direct cooling of the milk tubes (milk hoses).

In Fig. 5 there is shown a pre-cooler in the form of a flange-plate type heat exchanger 40. In this case four milk tubes 41,42,43,44 (conveying milk from the teat cups 11) are connected to the inlet ends 45a,46a,47a,48a of four U-shaped milk pipes 45,46,47,48 having outlet ends 45b,46b,47b,48b. The four milk pipes 45 - 48 pass through holes in a plurality of parallel plates 49, and the pipes and these plates together constitute the cooling coil unit 50 of the pre-cooler 40. In Fig 5 the cooling coil unit 50 is shown removed from, and placed to the left of the pre-cooler housing 51, wherein the unit is to be mounted. On the downstream side of the pre-cooler 40 four milk tubes 41 ',42', 43 ',44' are connected to the outlet ends 45b,46b,47b,48b of the milk pipes 45-48.

Claims

1. A method of cooling, during ongoing milking of an animal, e.g. a cow, milk extracted from the animal being milked by a quarter milking arrangement (10) com- prising four teat cups (11) and a tubing system (12, 13, 14) conveying the milk from the teat cups to a common, downstream milk tank (15) collecting the individual milk flows from the teat cups, characterised by the step of pre-cooling the milk from the teat cups (11) in a region (A;B;C;D) of the tubing system upstream of the common collecting tank (15) or alternatively directly downstream of the common collecting tank in a region (E) of a milk discharge tube (19) used for dr-iining off the milk from the tank.

2. A cooling method according to claim 1, characterised by the step of carrying out the pre-cooling of the milk in a region (A or B) of the tubing system (12) upstream of a milk flow meter assembly (16) being included in the tubing system between the teat cups (11) and the common collecting tank (15).

3. A cooling method according to claim 1, characterised by the step of carrying out the pre-cooling of the milk in a region (C or D) of the tubing system (13, 14) down- stream of a milk flow meter assembly (16) being included in the tubing system between the teat cups (11) and the common collecting tank (15).

4. A cooling method according to any of claims 1-3, characterised by the step of carrying out the pre-cooling of the milk flow from each teat cup (11) in a respective straight milk tube length (28) running parallel with three corresponding, individual, other milk tube lengths (29-31), which convey the milk flows from their respective teat cups of the quarter milking arrangement (10), the straight tube lengths (28-31) running through a cooling chamber (in 21) wherein the outsides of the tube lengths are cooled by a coolant fed through the chamber.

5. A cooling method according to any of claims 1-3, characterised by the step of carrying out the pre-cooling of the milk flow from each teat cup (11) in a respective coiled tube length running through a cooling chamber wherein the outside of the coiled tube length is cooled by a coolant fed through the chamber.

6. A cooling method according to claim 4 or 5, characterised by the step of using a gas, e.g. air, as the coolant being fed through the cooling chamber.

7. A cooling method according to claim 4 or 5, characterised by the step of using a liquid, e.g. water, as the coolant being fed through the cooling chamber.

8. A cooling method according to any preceding claim, characterised in that the method is applied in an automatic nώking system, preferably a system for voluntary milking.

9. A quarter milking airangement comprising four teat cups (11) connectable with the teats of an ani al to be milked, and a tubing system (12, 13, 14) conveying the milk from the teat cups to a common, first milk tank (15), wherein the individual milk flows from the teat cups are collected, characterised in that a pre-cooling means is connect- ed to and co-operates with the tubing system within a region (A;B;C;D) thereof between the teat cups (11) and the first milk tank (15) or, alternatively, is connected to and co-operates with a milk discharge tube (19), which conveys the collected milk away from the first milk tank, in a region (E) of that discharge tube situated directly downstream of the first milk tank.

10. A quarter milking arrangement according to claim 9, characterised in that the pre- cooling means comprises a recuperative heat exchanger included in the tubing system (12) in a region (A or B) thereof situated between the teat cups (11) and a milk flow meter assembly (16) included in the tubing system in a region thereof situated up- stream of the first milk-collecting tank (15).

11. A quarter milking arrangement according to claim 9 or 10, characterised in that the tubing system (12, 13) connects the teat cups (11) with a common milk flow meter (18) having a milk discharging pipe (14) for conveying the milk from the milk flow meter (18) to the first milk-collecting tank (15).

12. A quarter milking arrangement according to any of the claims 9-11, characterised in that the tubing system comprises an individual milk tube (12a, 13a; 12b, 13b etc.) extending from each teat cup (11), and that the pre-cooling means is a heat exchanger through which the milk flow from each teat cup is passed via the associated milk tube, which extends from the teat cup in question through the heat exchanger.

13. A quarter milking airangement according to any of the claims 10-12, characterised in that the heat exchanger is a flange-plate type heat exchanger (40).

14. A quarter milking airangement according to any of the claims 10-13, characterised in that the heat exchanger (20) comprises four individual milk tube lengths (28- 31) Ihrough which the milk flows from the four teat cups (11) pass, and the tube lengths extend Ihrough a common cooling chamber within the heat exchanger (20), and that the heat exchanger is provided with an inlet (22) and outlet (23) for passing a cooling fluid, i.e. a gas or a hquid, through the cooling chamber to effect a heat dissipation from the tube lengths to the cooling fluid passing through the cooling chamber.