TH E BACKGROU N D OF THE I NVENTION AN D PRIOR ART

The present invention relates to a milk sampling arrangement and a method for sampling of milk in a receiver.

Untreated milk stratifies into layers due to the different density of the substances included in the milk. An upper layer of the untreated milk includes, for example, a much hig her fat content than the lower layers. For this reason, it is known to provide milk receivers with a motor-driven stirrer or the like which agitates the milk in the milk receiver before a milk sample is taken. It is also known to supply air to the milk receiver in order to agitate the milk and provide a substantially homogenous distribution of the substances in the milk receiver before a milk sample is taken . However, all kinds of mechanical treatment of milk increase the content of free fatty acids (FFA) in the milk. A too high content of free fatty acids gives, for example, the milk a rancid taste.

US 8,327,799 shows an arrangement and a method for obtaining a representative sample of the milk in a receiver. In this arrangement, a pump and a return line are connected to the receiver. The pump pumps the milk from the receiver and back to the receiver via a return line. This milk flow provides a stirring motion of the milk in the receiver. After a certain period , the substances in the milk form a substantially homogenous distribution and it is possible to take a reliable sample of the milk in the receiver.

DE 1 6021 8 shows an arrangement where milk is collected in an open channel and , in order for a representative sample to be collected in the channel, stirred (together with the surrounding milk) using compressed air before the channel is closed. SUMMARY OF TH E I NVENTION

The object of the present invention is to provide a milk sampling device by which it is possible to take representative samples of the milk in a milk receiver without the risk that the free fatty acid content in the milk increases significantly.

This object is achieved by the milk sampling arrangement initially defined , which is characterized in that it comprises a separating device configured to separate a specific volume from the entire volume of the milk in the receiver, which separated volume of milk is in the form of a vertical slice containing the substances in the milk in substantially the same proportions as the entire volume of milk in the receiver, an agitation device configured to agitate the milk in the separated volume without agitating the milk outside the separated volume, and a sampling device configured to take a milk sample from the agitated milk in the separated volume, where the milk sample volume is substantially smaller than the separated volume.

Through this, a specific volume of the milk, which has the same composition of the included substances as the entire volume of milk in the receiver, is separated . Since the separated volume of milk is much larger than the required milk sample volume, the milk in the separated volume can be truly representative of the entire volume of milk in the receiver. The separated volume of milk is then agitated such that a substantially homogenous distribution of the included substances is obtained. Thereafter, a milk sample is taken from the homogenous milk in the separated volume. Through this, only a minor part of the milk in the receiver is agitated, i.e. the milk in the separated volume. Thereby, the content of free fatty acids will only increase in the separated part of the milk. Thus, the content of free fatty acids in the entire volume of milk in the receiver will increase much less than in a conventional milk sampling arrangement. According to an embodiment of the invention , the separating device is configured to separate a specific volume of milk having a constant area in all horizontal planes from a lower end located at a bottom wall of the receiver and up to an upper end located at the milk level in the receiver. Due to the different density of the included substances in the untreated milk, the amount of the individual substances in the milk will vary in a vertical direction of the receiver. However, the substances in one and the same horizontal plane in the receiver can be assumed to be uniformly distributed in said plane. The separated volume of milk has a vertical extension from the bottom wall of the receiver up to the milk level in the receiver, in the form of a vertical slice. Consequently, the milk in all horizontal planes is represented in the separated volume of milk. Furthermore, the separated volume of milk has a constant area in all horizontal planes. Thus, the milk in all horizontal planes is equally represented. Due to these facts, the separated volume of milk contains the included substances in substantially the same proportions as in the entire volume of milk.

According to an embodiment of the invention, the separated volume of milk is selected in a part of the receiver which comprises an outlet opening to a milk conduit. It is here possible to provide a flow of the separated milk from the inner space receiver to the milk conduit whereupon it is possible to provide a sample of the milk in the milk conduit. In this case, it is not necessary to take a sample of the separated milk when it is located inside of the receiver. According to an embodiment of the invention , the separating device comprises a separating body having an inner space in which said specific volume of milk is to be received and at least one opening to the inner space. The inner space of the separating body has a vertical extension which at least corresponds to a maximum milk level in the receiver. The milk quantity from individual milking processes varies and thus the milk level in the receiver when a milking process has finished. Since the inner space has the above mentioned vertical extension, it is always capable of accommodating the separated volume of milk. The inner space may have an arbitrary shaped cross sectional area. It may for example be circular, oval, quadrangular or polygonal. It is not necessary that the inner space has the same shape in all horizontal planes, but it needs to have the same area in all horizontal planes. According to an embodiment of the invention , the separating body comprises at least one wall of the receiver. In this case, the separating device may be an openable wall arrangement having an extension between two opposite side walls of the receiver such that it together with the walls of the receiver forms a closed inner space.

According to an embodiment of the invention, the whole separating body is arranged inside the receiver. Usually, a vacuum pressure is applied to a milk receiver in order to convey milk from teat cups to the receiver. It is suitable to arrange the whole separating body inside the milk receiver in order to avoid leakage of air into the receiver.

According to an embodiment of the invention , the separating body is provided with an opening to the inner space at a lower end and at least a part of the separating body is configured to be moved in a vertical direction between an upper position when the opening to the inner space is located above a maximum milk level in the receiver and a lower position in which the lower end of the separating body is placed on the bottom wall of the receiver such that the opening is closed by said bottom wall. When a milking process has finished, at least a part of the separating body is moved vertically downwards from the upper position to the lower position. It may be moved by a power member or manually by an operator. During this downwardly motion, the inner space of the separating body is successively filled with milk through the opening at the lower end. When the lower end of the at least part of the separating body reaches the bottom wall in the receiver, the opening is closed by the bottom wall. The inner space of the separating body now contains a separated volume of milk in the form of a pillar having a constant cross sectional area and a height corresponding to the milk level in the receiver.

According to an embodiment of the invention , the separating body constitutes a stationary unit, provided with a plurality of openings substantially uniformly distributed in a vertical direction from a lower end of the separating body up to an upper end of the separating body, in order to provide a substantially uniform flow of milk from all horizontal planes to the inner space. The openings may have any arbitrary shape, but each opening needs to at least have a size such that all substances in the milk are able to pass through the opening . However, the total area needs to be small enough to ensure that the milk outside of the separated volume is not agitated during the agitation process of the milk in the separated volume, due to the milk flow between the inner space and the surrounding space occurring rather slowly. Even if the area of the openings are small, there is enough time for the milk to flow into the inner space of the separating body during the period of the milking process and a subsequent period until the agitation process starts. These periods are much longer than the short agitating process, which may be in the order of just a few seconds. Such a separating body has a very simple construction with no movable parts. According to an embodiment of the invention , the separating body is provided with at least one elongated vertical opening having an extension from a lower end of the separating body up to an upper end of the separating body. Such an at least one opening makes it possible for milk in all horizontal planes to flow to the inner space from the surrounding space in the receiver. Thus the milk in all horizontal planes will be represented in the inner space. Preferably, the at least one elongated opening has a constant width in all horizontal planes from the lower end up to the upper end of the separating body. In this case, a uniform milk flow is provided from the surrounding space in the receiver to the inner space in all horizontal planes.

According to an embodiment of the invention, the separating body comprises a first stationary part comprising or defining said at least one opening , and a second movable part movably arranged between a non-closed position in which it does not close said at least one opening and a closed position in which it closes said at least one opening. In this case, the movable part is in the non-closed position during the milking process and the subsequent period until the agitation process starts. When it is time to start the agitation process, the movable part is moved to the closed position. The movable part is still in the closed position when the milk sample is taken . When the milk sample has been taken , the movable part is moved to the non-closed position such that the milk in the separated volume will be mixed with the milk in the surrounding volume of the receiver.

According to an embodiment of the invention , the separating body is cylinder-shaped and the stationary part and the movable part each comprises a curved wall forming a part of a circle in a horizontal plane, and an opening which comprises a missing part of the circle, wherein the curved walls are of a size such that they are able to form a closed circle, and the movable part is rotatably arranged at the outside or at the inside of the stationary part between said positions. The curved wall of the movable part may here be rotated in the order of 1 80° between the non-closed position, in which the openings of the stationary part and the movable part coincide, and the closed position , in which the curved wall of the movable part covers the opening of the stationary part. Alternatively, the separating body is cylinder-shaped and the stationary part and the movable part each comprises a plurality of curved wall parts which together form a circle with intermittent openings, wherein the curved walls are of a size such that they are able to form a closed circle, and the movable part is rotatably arranged at the outside or at the inside of the stationary part between said positions. I n this case, the movable part may be rotated a lesser angle between the non-closed position in which the openings of the stationary part and movable part coincide and the closed position in which the curved wall parts of the movable part covers the openings of the stationary part.

According to an embodiment of the invention, the stationary part and the movable part each comprises a plane wall, wherein the movable part is slidably arranged along a straight path between a non-closed position in which it does not close said at least one opening and a closed position in which it closes said at least one opening . Such a separating device may be given a simple design. The movable part may be slidably arranged along a straight path between two opposite walls in the receiver. Alternatively, the stationary part extends all the way between the two opposite walls of the receiver and comprises intermittent openings, and the movable part comprises corresponding intermittent openings, which coincide in the non-closed position. The movable part may then be slidably moved along the stationary part into a position where the solid parts of the movable part covers the intermittent openings of the stationary part.

According to an embodiment of the invention, the separating body has an inner space dimensioned to accommodate a separated volume of milk in the order of 1 -1 0% of the entire volume of milk in the receiver. The separated volume of milk should be as small as possible in order to reduce the formation of free fatty acids in an optimal manner. On the other hand, the risk that a separated volume of milk does not contain the included substances in a correct proportion increases significantly if the separated volume is very small. These two conditions are fulfilled in a desired manner in the above mentioned range.

According to an embodiment of the invention , the agitation device comprises an air supply device supplying air to the separated volume of milk. The air supply device may be an air line connected to the bottom of the receiver, and a valve. Alternatively, the air supply device may be connected to a valve in a milk line connected to the receiver. During occasions when a vacuum pressure prevails in the milk receiver, it is only necessary to open a valve such that air is sucked into the separated volume of milk. The supplied air performs a very effective agitation of the separated volume of milk. The air may be supplied to the separated milk during just a few seconds. Such an agitation device has a very simple construction.

According to an embodiment of the invention, the agitation device comprises a mechanical agitation component arranged inside the separated volume of milk in the receiver. Such a mechanical agitation component may be an impeller or the like driven by a motor. The agitation process with the impeller may be performed during just a few seconds.

According to an embodiment of the invention , the agitation device comprises a pump and a milk line having an opening in a wall of the receiver at one point in the separated volume of milk and an outlet opening in a wall of the receiver at a second point in the separated volume of milk, wherein the pump is configured to pump milk from the first point of the separated volume of milk to the second point of the separated volume of milk. The milk is preferably pumped from a lower end of the separated volume of milk to an upper end of the separated volume of milk. Such a milk flow provides an effective mixing of the milk in the separated volume. Since the separated volume of milk is small, the operation time of the pump may be short. According to an embodiment of the invention , the sampling device comprises a milk sampling line having an opening in a wall of the receiver to the separated volume of milk and a valve by which it is possible to control the milk flow through the milk sampling line to a sampling container. The milk sampling line may be connected to a bottom wall of the receiver. Preferably, the vacuum pressure to the milk receiver is shut off before a milk sample is taken such that the milk flows downwardly by gravity through the milk sampling line to the sampling container.

The initially defined object is also achieved by the method defined in claim 20 which is characterized by the steps of separating a specific volume from the entire volume of the milk in the receiver, which separated volume of milk is in the form of a vertical slice containing the substances in the milk in substantially the same proportions as in the entire volume of milk, providing agitation of the milk in said separated volume of milk without agitating the milk outside the separated volume, and taking a milk sample from the agitated and separated volume of milk, where the milk sample volume is substantially smaller than the separated volume.

BRI EF DESCRI PTION OF TH E DRAWINGS

The present invention is now to be explained more closely by means of preferred embodiments which are disclosed as examples and with reference to the attached drawings.

Fig . 1 shows a milk conveying system comprising a milk receiver,

Fig . 2 shows an embodiment of a milk sampling arrangement according to the invention,

Fig . 3 shows the milk sampling arrangement in Fig . 2 in a milk sampling state,

Fig . 4 shows a further embodiment of a milk sampling arrangement according to the invention, Fig . 5 shows a cross section view of the separating body in the plane A-A in Fig. 4,

Fig . 6 shows the separating body in Fig . 4 in a milk sampling state,

Fig . 7 shows a cross section view of the separating body in the plane A-A in Fig . 6,

Fig . 8 shows a cross section view of a further embodiment of a separating body according to the invention, Fig . 9a shows a cross section view of the separating body in

Fig . 8,

Fig . 9b shows a cross section view of the separating body in

Fig . 8 in a milk sampling state,

Fig . 1 0 shows a further embodiment of a milk sampling arrangement according to the invention,

Fig . 1 1 shows the separating body in Fig. 1 0 more in detail , Fig . 12 shows a further embodiment of a milk sampling arrangement according to the invention,

Fig . 1 3a shows a cross section view of the separating body in

Fig . 12 in a non-closed state, and

Fig . 1 3b shows a cross section view of the separating body in

Fig . 8 in a closed state.

BRI EF DESCRI PTION OF PREFERRED EMBODI M ENTS OF THE I NVENTION

Fig 1 shows a m ilk conveying system in a milking stall of a milking parlour. The milk conveying system comprises four teat cups 1 . Each teat cup 1 is connected to a milk tube 2. Each milk tube 2 is provided with a flow meter 3 and a control valve 4. The milk tubes 2 are adapted to convey milk from the teat cups 1 to a milk receiver 5. A vacuum source 6 is connectable to the milk receiver 5 by means of a vacuum line 7 and a vacuum valve 8. A milk sampling arrangement 9 is schematically disclosed for sampling of the milk in the receiver 5. The milk conveying system further comprises a milk conduit 1 0 conveying milk from the milk receiver 5 to a main milk tank 1 1 for a plurality of milking stalls in the milking parlour. A pump 12 is arranged in the milk conduit 1 0. The milk flow through the milk conduit 1 0 to the main tank 1 1 is controlled by a control valve 1 3. When a milking process of a cow is to be performed, a milking robot or an operator attaches the teat cups 1 to the teats of the cow in the milking stall . The vacuum valve 8 is set in a first position such that the vacuum source 6 is connected to the milk receiver 5. Thereby, a vacuum pressure is applied to the milk receiver 5. The milk is sucked from the teat cups 1 , via the milk tubes 2, to the milk receiver 5. When the milking process has finished, the vacuum valve 8 is set in a second position in which air of ambient pressure is applied to the milk receiver 5. The milk from each cow in the receiver 5 can be tested by means of the milk sampling arrangement 9. The design and function of the milk sampling arrangement 9 is described below. When a milking process has been completed and a milk sample has been taken, the pump 12 is activated and pumps the milk from the milk receiver 5 , via the milk conduit 1 0, to the main milk tank 1 1 .

Figs. 2 and 3 show a first embodiment of the milk sampling arrangement 9. The milk sampling arrangement 9 comprises a separating body 14. The separating body 14 is provided with a cylinder-shaped inner space 14a. The inner space 14a has a vertical extension from an opening 14b at a lower end of the separating body up to a closed upper end. The inner space 14a has a constant cross section area from the lower end up to the upper end. The constant cross sectional area may have any arbitrary shape. It may be circular, oval , quadrangular, polygonal etc. The milk volume in the inner space 14a of the separating body 14 is in the order of 1 -1 0 % of the entire volume of milk in the receiver 5. The separating body 14 is displaceably arranged in a vertical direction through a hole in an upper wall 5a of the receiver 5. A sealing 15 provides a sealed connection between the separating body 14 and the upper wall 5a of the receiver 5.

An extensible power member 16 is arranged to displace the separating body 14 between an upper position where it is in an inactive state and a lower position where it is in a milk sampling state. Fig. 2 shows the separating body 14 in the upper position and Fig. 3 shows the separating body 14 in the lower position. The power member 16 has one end connected to a stationary wall or the like arranged outside the receiver 5 and an opposite end connected to an upper part of the separating body 14. The power member 16 may be a pneumatic cylinder or a hydraulic cylinder. In the upper position of the separating body 14, the opening 14b to the inner space 14a of the separating body 14 is located above a maximum milk level 17a in the receiver 5. Such a maximum level 1 7a may be defined by a smallest acceptable vertical distance between an opening to the vacuum line 7 and the milk level 17 in the receiver 5. In this case, the milk level 17 in the receiver 5 is somewhat lower than the maximum milk level 17a. In the lower position of the separating body 14, the lower end of the separating body 14 is placed on an inner surface 5b of a bottom wall of the receiver 5. A suitable activation member 18 activates the extensible power member 16 when it is time to displace the separating body 14. Such an activation member 1 8 may be a button or the like which is controlled by a person which takes milk samples. Alternatively, it is a control unit which automatically displaces the separating body 14 to the lower position when a milk sample is to be taken and back to the upper position when the milk sample has been taken . Alternatively, the separating body may be manually moved from the upper position to the lower by an operator.

A milk sample line 1 9 has an opening in the bottom wall 5b of the receiver within an area covered by the opening 14b to the inner space 14a of the separating body 14 in the lower position. The milk sample line 1 9 comprises a control valve 20 by which it is possible to control the flow of milk through the milk sample line 1 9. A milk agitating device in the form of an air line 21 is arranged at the receiver 5. The air line 21 has an opening in the bottom wall 5b of the receiver 5 within an area covered by the opening 14b to the inner space 14a of the separating body 14 in the lower position . The air line 21 comprises a control valve 22 by which it is possible to supply ambient air to the inner space 14a of the separating body. Instead of using a separate air line 21 , an air inlet could be integrated in a valve in milk sample line 19.

During a milking process of an animal in the milking stall , the milk is conducted to the milk receiver 5. The milk is untreated and stratifies into layers in the milk receiver 5. An upper layer of the milk in the milk receiver 5 includes, for example, a much higher fat content than the lower layers. When the milking process has been completed, it is possible to test the milk in the receiver 5. In this case, the activation member 1 8 activates the power member 16 is such that it displaces the separating body 14 downwardly from the upper position to the lower position. Since the separating member 14 comprises an opening 14b to the inner space 14a at the lower end, the inner space 14a is successively filled with milk. When the separating body 14 reaches the bottom 5b of the receiver 5, it contains a milk pillar which has been separated from the volume of milk in the receiver 5. The separated volume of milk contains milk from all horizontal planes and layers in the receiver 5. Since the inner space has a constant cross sectional area, all horizontal planes and layers are equally represented in the inner space. Consequently, the separated volume of milk in the inner space 14a of the separating body 14 is in the form of a vertical slice which is representative of the entire volume of milk in the receiver 5. Thereafter, the control valve 22 in the air line 21 is open. Since a vacuum pressure prevails in milk separating body 5, air with ambient pressure flows, via the air line 21 , to the inner space 14a of the separating body 14. The supplied air provides an effective mixing of the separated volume of milk in the inner space 14a. The air is supplied during a few seconds. Such an agitation process forms a homogenous mixture of the different layers and substantially all included substances in the milk in the inner space 14a of the separating body 14.

As soon as the agitation process of the milk is finished, the vacuum valve 8 is set in the second position such that ambient air pressure is applied to the milk receiver 5. It is now possible to open the valve 20 and obtain a milk flow from the inner space 14a of the separating body 14, via the milk conduit 1 9 to a milk sampling container which may be a test tube 23. When the milk sampling process is finished, the activation member 1 8 activates the power member 16 such that it displaces the separating body 14 back to the upper position. It is now possible for the remaining milk in the inner space 14a of the separating body 14 to be mixed with the surrounding milk in the receiver 5. The pump 12 is activated and the valve 13 is set in an open position . The pump 12 pumps the milk from the receiver 5 to the main milk tank 1 1 where it is mixed with milk from other milking stalls.

Mechanical treatment of milk such as mixing of the milk increases the content of free fatty acids (FFA) in the milk. In a conventional milk sampling arrangement, the whole volume of milk is agitated before a milk sample is taken. In this case, only a small part of the entire volume of milk in the receiver 5 is subjected to an agitation process i.e. the milk in the separated volume. This does not significantly increase the content of free fatty acids in the entire volume of milk in the receiver 5.

Figs. 4-7 show an alternative embodiment of the milk sampling arrangement 9. I n this case, the milk sampling arrangement 9 comprises a separating body 24 in the form of a stationary part 24a and a rotatable part 24b. The stationary part 24a and the rotatable part 24b each comprise a curved wall 24a _{1 ;} 24b-i forming a part of a circle in a horizontal plane A-A. The curved wall 24ai of the stationary part 24a and the curved wall 24^ of the rotatable part 24b have a common centre of curvature 25. The curved wall 24b _! of the rotatable part 24b has an outer surface with substantially the same dimensions as an inner surface of the curved wall 24a _! of the stationary part 24a. The curved wall 24b _! of the rotatable part 24b is here arranged on the inside of the curved wall 24a _! of the stationary part 24a.

The missing parts of the circle of the curved wall 24ai of the stationary part 24a and the curved wall 24bi of the rotatable part 24b are shown with dotted lines in Fig . 5 and 7. The missing part of the stationary part 24a forms an opening to an inner space 26 of the separating body 24. The missing part of the stationary part 24b also forms an opening 24b ₂ to the inner space 26 of the separating body 24. The curved circular walls 24a-i , 24b _! of the stationary part 24a and the rotatable part 24b have a size such that they are able to form a closed circle. The stationary part 24a and the rotatable part 24b of the separating body 24 are arranged inside a milk receiver 5. The stationary part 24a and the rotatable part 24b each have an extension in a vertical direction from a lower end at the bottom wall 5b of the milk receiver 5 up to an upper end which at least is located at the maximum milk level 17a. Thus, the upper ends of the stationary part 24a and the rotatable part 24b are always located at a higher level than the milk level 17 in the milk receiver 5. The inner space 26 is formed as a circular cylinder. Thus, it has a constant cross sectional area in a vertical direction from the bottom wall 5b up to the upper end of the separating body 24. The inner space 26 has an opening at a lower end at the bottom wall 5b of the receiver 5. The openings 24a ₂ , 24b ₂ of the stationary 24a part and the rotatable part 24b each have a continuous extension in the whole vertical extension of the separating body 24. The openings 24a ₂ , 24b ₂ have the same width in all horizontal planes.

Fig . 5 shows the separating body 24 in a non-closed position , in which the opening 24b ₂ of the rotational part 24b coincides with the opening 24a ₂ of the stationary part 24a. Fig. 7 shows the separating body 24 in a closed position, in which the curved wall 24b _! of the rotational part 24b covers the opening 24a ₂ of the stationary part 24a. A power member 27 is arranged at the upper wall 5a of the milk receiver 5. An activation member 28 is configured to activate the power member 27 such that it rotates the rotatable part 24b in relation to the stationary part 24a. The power member 27 is configured to rotate the rotatable part 24b between the non-closed position and the closed position . The power member 27 may be a pneumatic cylinder or an electric motor. The control member 28 may be a button or the like which is manually controlled by a operator. Alternatively, it may be a control unit which automatically rotates the rotatable part 24b to the closed position when a milk sample is to be taken and back to the non-closed position when the milk sample has been taken . According to a further alternative, the rotatable part 14b is connected to a rotatable pin or the like which is manually rotatable by an operator. A milk sample line 1 9 is arranged at the bottom wall 5b of the receiver 5. The milk sample line 19 has an opening in the bottom wall 5b within the area of the separated volume of milk in the inner space 26 of the separating body 24. The milk sample line 1 9 comprises a control valve 20 by which it is possible to obtain a milk flow from said separated volume of milk in the inner space 26. A milk agitating device in the form of a pump 28 and a milk line 29 is connected to the milk receiver 5. The milk line 29 has an inlet opening in a bottom wall 5b of the receiver 5 within the area of the inner space 26 and an outlet opening in an upper wall 5a of the receiver 5 within the area of the inner space 26. Instead of using a separate milk sample line 19, it would be possible to integ rate a milk sampling outlet in a valve in milk line 29.

When a milking process of an animal in the milking stall proceeds, the milk is sucked to the milk receiver 5. The rotatable part 24b of the separating body is positioned in the non-closed position such that the milk fills up the inner space 26 and the surrounding space in the receiver 2 substantially simultaneously. When the milking process has finished , the milk in the inner space 26 has the same composition as the milk in the surrounding space in the receiver 5. The vacuum valve 8 is set in the second position such that ambient air pressure is applied to the milk receiver 5. The activation member 28 activates the power member 27 such that it rotates the rotatable part 24b of the separating body 24 to the closed position . The milk in the inner space 26 is now in the form of a vertical slice which is completely separated from the milk in the surrounding space of the receiver 5. Thereafter, the pump 28 is activated such that it pumps milk from a bottom portion of the inner space 26 to an upper portion of the inner space 26. The milk flow provides an effective mixing of the milk in the inner space 26. After a few seconds the milk in the inner space 26 has formed a substantially homogenous mixture of all included substances in the milk. As soon as the agitation process of the milk in the inner space 26 is finished , it is possible to open the valve 20 and take a milk sample of the milk in the separated volume of milk. When the valve is open, milk flows from the inner space 26, via the milk conduit 1 9, to a test tube 23. As soon as the milk sampling process is finished, the activation member 28 activates the power member 27 such that it rotates the rotatable part 24b back to the non-closed position . It is now possible for the separated homogenous milk in the inner space 26 to be mixed with the surrounding milk in the receiver 5. The pump 12 is activated and the valve 13 is set in an open position . The pump 12 pumps the milk from the receiver 5 to the main milk tank 1 1 where it is mixed with milk from other milking stalls. Since the agitation process of the milk is restricted to the relatively small inner space 26 of the separati ng body 24 , the agitating process does not significantly increase the content of the free fatty acids i n the entire volume of the milk in the receiver 5.

Fig . 8 shows a further embodiment of a separating body 30. The separating body 30 comprises a stationary part 30a and a rotatable part 30b. The stationary part 30a and the rotatable part 30b may have a vertical extension in substantially the whole internal height of the internal space of the receiver 5. The stationary part 30a and the rotatable part 30b each com prise a cylindrically shaped hollow body with a circular cross sectional area. The stationary part 30a and the rotatable part 30b each comprise a plurality of curved wal ls 30a-i , 30^ forming the circular shape of the separating bodies 30a, 30b and intermittent openi ngs 30a _{2 l} 30b ₂ . The curved wall parts 30a _! , 30b-i and the openings 30a ₂ , 30b ₂ each have a vertical extension in substantially the whole height of the separating body 30. The curved wall parts SOa^ 30bi of the stationary part 30a and the rotatable part 30b com prises elongated wall elements connected to each other at an u pper end and at a lower end by means of a respective annular connection member 30c. The cylinder shaped stationary part 30a and the rotatable part 30b have openings 30d at the upper end and at the lower end .

Figs. 9a and 9b show a horizontal cross section view of the cylind rically shaped parts 30a, 30b. The curved wall parts 30&· _\ , 30bi of the stationary part 30a and the rotatable part 30b have a com mon centre of cu rvature 31 . The rotatable part 30b has an outer surface with substantially the same size as an inner surface of the stationary part 30a. The rotatable part 30b is arranged on the inside of the stationary part 30a. The stationary part 30a defines an i n ner space 32 around the common centre of curvature 25. Such a separating body 30 may be used i nstead of the separating body 24 shown in Fig . 6. Also in this case, a power member 27 may be arranged at the upper wall 5a of the milk receiver 5 and an activation member 28 configured to activate the power member 27 and rotate the rotatable part 30b in relation to the stationary part 30a.

The rotatable part 30b is rotatable between a non-closed position which is shown in Fig . 9a and a closed position which is shown in Fig . 9b. In the non-closed position, the openings 30a ₂ , 30b ₂ of the stationary part 30a and the rotatable part 30b coincide such that a milk flow is allowed between the inner space 32 and the surrounding space in the receiver 5. In the closed position , the curved wall parts 30b-i of the rotatable part 30b cover the openings 30a ₂ of the stationary part 30a. The function of the milk separating device 30 corresponds substantially to the function of the separating body 24 in Fig . 6. However, the rotary motion of the rotatable part 30b between the non-closed and the closed position is smaller than the corresponding motion of the rotatable part 24b of the separating body 24.

Figs. 10 and 1 1 show a further alternative embodiment of the milk sampling arrangement 9. In this case, the milk sampling arrangement 9 comprises a separating body 35 formed as a hollow cylinder with an inner space 36. The separating body 35 is a single unit having a stationary position in a receiver 5. The separating body 35 has a vertical extension between a bottom wall 5b of the receiver 5 and an upper wall 5a of the receiver 5. The inner space 36 has an extension between an opening 35b at a lower end and an opening 35b at an upper end. The inner space 36 has a constant cross section area in its vertical extension between the lower end and the upper end. The separating body 35 is provided with a plurality of small openings 35a. The openings 35a are uniformly arranged at least in a vertical direction of the separating body 35 such that at least one opening 35a is arranged in each horizontal plane between the lower end and the upper end of the separating body 35.

A milk sample line 1 9 has an opening in the bottom wall 5b of the receiver 5 within an area covered by the inner space 36 of the separating body 35. The milk sample line 1 9 comprises a control valve 20 by which it is possible to provide a milk flow from the inner space 36 of the separating body 35. A milk agitating device in the form of rotatable mechanical mixing component is mounted in the inner space 36 of the separating body 35. In this case, the rotatable mechanical mixing component is an impeller 37. The impeller 37 is driven by an electric motor 33. An activation member 34 controls the activation of the electric motor 33 and the operation of the impeller 35. Such an activation member 34 may be a button or the like which is activated by an operator. Alternatively, it may be a control unit which automatically starts the rotary motion of the impeller 37 and the mixing process of the milk in the inner space 36 of the separating body 35 before a milk sample is to be taken.

When a milking process of an animal in the milking stall has finished, the milk from the milking process is collected in the milk receiver 5. The openings 35a of the separating body 35 have a size such that it is possible for all substances in the milk to penetrate through the openings 35a and to the inner space 36 of the separating body 35. However, it takes considerable time for the milk to flow into the inner 36 space, since the total area of the openings 35a is small in relation to the volume in the inner space 36. However, the milking process and the subsequent period until an agitation process starts are relatively long . There is thus time to fill up the inner space 36 to the same level as the surrounding milk level before the agitation process starts. Since the openings 35a are uniformly arranged in the vertical direction, the milk in the inner space has substantially the same composition as the milk in the surrounding space of the receiver 5. Consequently, the separated volume of milk in the inner space 36 of the separating body 35 is in the form of a vertical slice which is representative of the entire volume of milk in the receiver 5.

The control member 34 activates the electric motor 33 such that it rotates the impeller 37 in the inner space 36. The impeller 37 provides an effective mixing of the volume of milk in the inner space 36 and thus of said layers in the milk. The impeller 37 may be activated during just a few seconds. Since the openings 35a in the separating body 35 have a relatively small total area, the milk flow between the inner space and the surrounding space in the receiver will be subsequently negligible during such a short period. Such a separating body 35 has a simple construction with no movable part. As soon as the agitation process of the milk in the inner space is finished, the valve 20 is opened such that a suitable amount of homogenous milk flows from the inner space 36 of the separating body 35, via the milk conduit 19, to the test tube 23. When the milk sampling process is finished , the pu mp 12 is activated and the valve 1 3 is set in an open position . The milk is pumped from the receiver 5 to the main milk tank 1 1 where it is mixed with milk from other milking stalls. Also in this case, the agitation process is performed only in the separated volume, without agitating the rest of the milk in the receiver 5. Thereby, the content of free fatty acids in the entire volume of milk in the receiver 5 does not increase significantly.

Fig . 12 shows a fu rther alternative embodiment of the milk sampling arrangement 9. I n this case, the milk sampling arrangement 9 comprises a separating body in the form of a wall arrangement 38 arranged inside a milk receiver 5. The wall arrangement 38 comprises a stationary wall 38a and a movable wall 38b. The stationary wall 38a and the movable wall 38b each have an extension in a vertical direction from a lower end at the bottom wall 5b of the milk receiver 5 up to an upper end which at least is located at the maximum milk level 17a. Thus, the upper ends of the stationary wall 38a and the movable wall 38b are always located at a higher level than the milk level 1 7 in the milk receiver 5. The wall arrangement 38 is arranged at a relatively small distance from a short side wall 5e of the receiver 5.

Figs. 1 3a and 1 3b show a view through the wall arrangement 38 in the horizontal plane C-C in Fig . 12. It is here visible that the stationary wall 38a has a horizontal extension between an end connected to a front long side wall 5c of the receiver 5and a free end located in a position substantially midway between the front long side wall 5c and a rear long side wall 5d of the receiver 5. The movable wall 38b has substantially the same size as the stationary wall 38a. Fig 13a shows the movable wall 38b in a non-closed position in which it is arranged at the side of the stationary wall 38. The movable wall 38b is slidably arranged along a substantially straight path from the non-closed position to a closed position in which it comes in contact with the rear long side wall 5d of the receiver 5. Thus, the wall arrangement 38 has a substantially straight line extension between the oppositely located long side walls 5c, 5d of the receiver 5 in the closed position . The stationary wall 38a forms a part of said straight line. The missing part of the straight line is defined as an opening 38c to an inner space 39 which is formed by the wall arrangement 38 together with the front long side wall 5c, the rear long side wall 5d and the short side wall 5e of the receiver 5. In this case, an outlet opening 1 0a to the milk conduit 1 0 is arranged in said inner space 39.

A power member 40 is arranged at the upper wall 5a of the milk receiver 5. An activation member 41 is configured to activate the power member 40 such that it slides the movable wall 38b in relation to the stationary wall 38a. The power member 40 is configured to move the movable wall 38b between the non- closed position and the closed position . The power member 40 may be a pneumatic cylinder, a hydraulic cylinder or an electric motor. The control member 41 may be a button or the like which is manually controlled by an operator. Alternatively, it may be a control unit which automatically slides the movable wall 38b to the closed position when a milk sample is to be taken and back to the non-closed position when the milk sample has been taken . According to a further alternative, the movable wall 38b is connected to a pin or the like arranged at the outside of the receiver which is manually movable by an operator.

In this case, the milk flow from the receiver 5 to the milk conduit 10 is controlled by a control valve 42 in the form a of a three way valve 42. The three way valve 42 may be in a closed position , an open position and a sampling position . In the sampling position, it is possible to take a sample of the milk in the milk conduit 1 0. A milk agitating device in the form of an air line 21 is connected to the milk conduit 1 0 in a position close to the receiver 5. The air line 21 comprises a control valve 22 by which it is possible to supply ambient air to the milk conduit 1 0 and to the inner space 39. Instead of using a separate air line 21 , an air inlet could be integrated in a valve in the milk conduit 1 0, for example in the valve 42.

When a milking process of an animal in the milking stall proceeds, the milk is sucked to the milk receiver 5. The movable wall 38b is positioned in the non-closed position such that the milk fills up the inner space 39 and the surrounding space in the receiver 5 substantially simultaneously. When the milking process has finished , the milk in the inner space 39 has the same composition as the milk in the surrounding space in the receiver 5. The vacuum valve 8 is set in the second position such that ambient air pressure is applied to the milk receiver 5. The activation member 41 activates the power member 40 such that it slides the movable wall 38b to the closed position . The milk in the inner space 39 is now in the form of a vertical slice which is completely separated from the milk in the surrounding space of the receiver 5.

Thereafter, the control valve 22 in the air line 21 is open . Since a vacuum pressure prevails in milk separating body 5, air with ambient pressure flows, via the milk conduit 1 0, to the inner space 39. The supplied air provides an effective mixing of the separated volume of milk in the inner space 39. The air is supplied during a few seconds. Such an agitation process forms a homogenous mixture of the different layers and substantially all included substances in the milk in the inner space 39.

As soon as the agitation process of the milk is finished, the vacuum valve 8 is set in the second position such that ambient air pressure is applied to the milk receiver 5. It is now possible to set the three way valve 42 in a sampling position such a milk flow is obtained from the inner space 39, via the outlet opening 10a and the milk conduit 1 0, to a test tube 23. When the milk sampling process is finished, the activation member 41 activates the power member 40 such that it slides the movable wall 38b back to the non-closed position. It is now possible for the remaining milk in the inner space 39 to be mixed with the surrounding milk in the receiver 5. The three way valve 42 is set in the open position. The pump 12 is activated and the milk is pumped from the receiver 5 to the main milk tank 1 1 where it is mixed with milk from other milking stalls.

In an alternative embodiment (not shown), instead of the stationary wall 38a and the movable wall 38b both being solid and extending halfway through the receiver 5, the stationary wall extends all the way from a front long side wall 5c of the receiver 5 to a rear long side wall 5d of the receiver 5 and comprises intermittent openings, in the same way as in the embodiment according to Fig . 8. The movable wall must then comprise corresponding intermittent openings. In the non-closed position of the movable wall , the openings coincide such that a milk flow is allowed between the inner space 39 and the surrounding space in the receiver 5. In the closed position of the movable wall , the solid wall parts of the movable wall cover the intermittent openings in the stationary wall . The function corresponds su bstantially to the function of the wall arrangement 38 in Fig. 12, but the movement of the movable wall between the non-closed and the closed positions is smaller than the corresponding movement of the movable wall 38b of the wall arrangement 38 in Fig . 12.

The invention is not restricted to the described embodiment but may be varied freely within the scope of the claims. In the above described embodiments different kinds of separating devices and agitation devices are used . It is of course possible to use other combinations of separating devices and agitation devices than the combinations shown in the embodiments. Further, if a milk agitating device in the form of an air inlet is used, it is possible to integrate this air inlet into a valve in the milk sample line or in the milk line, so that no separate air line is necessary.