Milking device

Abstract

There is provided a milking device (1) comprising milking cups (5). The milking cup comprises a cup housing (20), a teat lining (21) which surrounds a teat space (22) with a cup milk discharge opening (24), a pulsation space (25), and a chamber (29) for receiving the milk obtained and for separating milk and air. The chamber has a milk supply opening (27) which is in liquid communication with the cup milk discharge opening, and a chamber milk discharge opening (32), and a separate chamber air discharge opening (31) which is situated above the chamber milk discharge opening. The milking device furthermore has a control unit (12), a milk-collecting vessel (11) for temporarily accommodating the milk of one milking operation, a milking hose (9) between the chamber milk discharge opening and the milk-collecting vessel, and a controllable vacuum device (6) configured to apply a pulsation vacuum Vp to the pulsation space, a milking vacuum Vm to the chamber, and a transport vacuum Vt to the milk-collecting vessel. The vacuum device is configured for setting the transport vacuum Vt as a function of a milking parameter. Due to the milk / air separation, the transport vacuum is independent from the milking vacuum. Due to the adjustability of the transport vacuum, the milking operation can be adjusted in a more satisfactory manner to the desire for an optimum milking operation.

Description

[0001] Milking device

[0002] The present invention relates to a milking device for milking a dairy animal with teats, comprising at least one milking cup to be attached to one of the teats, which milking cup comprises a cup housing, a teat lining which is arranged in the cup housing and surrounds a teat space with a teat opening and a cup milk discharge opening, wherein a pulsation space with a pulsation opening is situated between the teat lining and the cup housing, a chamber which is configured to receive the milk obtained and to separate milk and air, which chamber extends during said milking from the cup milk discharge opening in a fluid-connected manner, wherein said chamber comprises a milk supply opening which is in liquid communication with the cup milk discharge opening, and a chamber milk discharge opening, as well as a separate chamber air discharge opening which is situated above the chamber milk discharge opening during said milking operation, wherein the milking device furthermore comprises a control unit, a milkcollecting vessel for temporarily accommodating the milk of one milking operation, with a vessel milk supply opening, a milking hose connected between the chamber milk discharge opening and the vessel milk supply opening, and a vessel air discharge opening, a controllable vacuum device configured to apply a pulsation vacuum VPto the pulsation space via the pulsation opening, a milking vacuum Vm to the chamber via the chamber air discharge opening, and a transport vacuum Vt to the milk-collecting vessel and the milking hose via the vessel air discharge opening, wherein the vacuum device is configured for setting the transport vacuum Vt as a function of a milking-related parameter.

[0003] Milking devices have been known per se for more than a hundred years. Milking devices work almost exclusively by applying a milking vacuum to a milking cup attached to a teat, by means of which milk is sucked out of the teat. This milk is sucked out of the milking cup and transferred to a milk glass or sometimes directly to a milk tank, by means of a transport vacuum. With most milking cups, the transport vacuum and the milking vacuum are applied via the same line, the milking hose, to the milking cup, and thus to the teat. The milking vacuum is then effectively only the result of that which remains from the transport vacuum below the teat on account of the milk flow from this teat.

[0004] A milking device of the kind mentioned in the introduction is known per se from US2020084994A1 .

[0005] A drawback of the known milking device is that it is not always optimally adapted to the demands made by the milking of the dairy animals, both with regards to physical demands on the animals and demands on the milk.

[0006] It is therefore an object of the invention to improve a milking device of the kind mentioned in the introduction in such a way that it is more easily adaptable to the demands made on the milking and the milk.

[0007] This object is achieved by the invention by means of a milking device according to Claim 1 . The invention is based on understanding that the transport vacuum with this type of milking device is in principle independent from, in particular, the milking vacuum, due to the fact that air is extracted via a separate discharge, above the chamber milk discharge opening. As a result thereof, the milk may be collected and discharged as a single-phase liquid, and the functions of both vacuums can be separated. The milking vacuum draws milk from the teat, and the transport vacuum transports the milk. This last function can thus be set independently from the actual milking requirements, such as “very careful” with milk which should be treated carefully. This is important, for example, in the production of cheese or other dairy products, where the amount of free fatty acids is to be limited as much as possible, which may be effected by treating the milk as carefully as possible, i.e. by a which is as subtle as possible. On the other hand, there may be cases where a dairy animal has a particularly high milk flow. In order to prevent the chamber from filling with milk, it may be necessary to increase the transport vacuum for this dairy animal, so that even this high milk flow can be sucked out of the chamber in a controlled manner. It will be clear that the adjustability of the transport vacuum offers this possibility as well as other options.

[0008] It should be noted here that this adjustability, in particular of a milking- related parameter, is not mentioned or elaborated on in said document US2020084994A1 . Obviously, a choice will have been made at some stage for the transport vacuum, just as with the milking devices using conventional milking cups. But with these milking devices, the transport vacuum cannot even be adjusted or varied as such, since it is inextricably linked to the milk flow. And in the aforementioned document, no connection is made with the milking parameter in order to adjust this transport vacuum. The advantages of the present invention will therefore not occur there.

[0009] With the milking device according to the present invention, the vacuum device comprises customary components, such as a vacuum pump, a sanitary trap, etc. In particular, there are provided a pulsating line connected to the pulsation opening, a milk vacuum line connected to the chamber air discharge opening, and a transport vacuum line connected to the vessel air discharge opening. Such components are all well-known to the person skilled in the art. In addition, in the present application, a "vacuum value" denotes the magnitude of a negative pressure with respect to ambient pressure, so that a "higher vacuum" or "greater vacuum" actually means a lower absolute pressure.

[0010] Particular embodiments are described in the dependent claims, as well as in the following part of the description.

[0011] The aforementioned parameter is not particularly limited. Some examples are mentioned in this application.

[0012] In embodiments, said parameter comprises said milking vacuum Vm to be provided during the milking operation. The pressure, the force, with which the milk is effectively discharged from the chamber depends on the difference between the pressure in the chamber, or the milking vacuum, and the pressure in the milk-collecting vessel. By setting the transport vacuum as a function of the milking vacuum, the discharge of the milk from the chamber can be controlled in an optimum manner. It should be noted that the milking vacuum could be set, for example, as a function of the milk flow, or of the phase of the milking operation (starting phase, plateau phase, finish milking phase, postmilking phase). It should furthermore be noted that with conventional milking cups, the milking vacuum to be provided cannot be controlled or cannot be controlled well, due to the fact that the milking vacuum is only influenced indirectly, and cannot be actively adjusted. The reason for this is that the milk flow varies during milking, and with a higher milk flow, the milking vacuum is effectively reduced. In addition, the milking vacuum is also already slightly lower due to the supply of air to the milking cup, which is necessary for transporting the milk obtained. Except for this last effect, the milking vacuum to be provided is actually in principle the vacuum prevailing at the teat during the milking operation with milking devices of the present type.

[0013] The way in which the control unit sets the transport vacuum as a function of the milking vacuum is not limited in any particular way either. For example, the control unit is configured to set the transport vacuum Vt equal to the milking vacuum Vm plus a predetermined pressure difference. Due to the fact that the pressure difference is in principle now constant, the discharge speed is consequently also in principle now constant. For example, said predetermined pressure difference is between 2 and 10 kPa, more particularly between 5 and 10 kPa. At such pressure differences, a quick milk discharge is ensured, without the milk being exposed to excessive loads and without an excessive amount of air being sucked along (air entrapment). Nevertheless, other values, in particular higher values, are still possible, for example for milk which is destined for human consumption, or if the distance between milking cup and milk receptacle is very large.

[0014] In alternative or additional embodiments, said parameter comprises an elevation height ho of the milk obtained in the milking hose. The understanding with these embodiments is that the effective transport vacuum can be influenced by the height over which the milk has to be raised from the chamber to the milk-collecting vessel. The reason for this is that in this case the force of gravity will either have a positive or an adverse effect. In particular, the parameter may be chosen to be equal to pmiik*g*ho. In this case, pmiik is the density of milk (±1 kg / dm3), and the elevation height is the difference in height between a chamber level hk of the milk in the chamber and a front level hf of a front boundary of milk provided in the milking hose. This height difference determines the milk column which the transport vacuum has to displace, almost always upwards, except for example in milking parlours using conventional milking devices. Obviously, during a milking operation, the front level also starts in the chamber, and will rise to the highest point of the milking hose as the milking operation progresses. If that is not the vessel milk supply opening, i.e. if the milk subsequently drops to this vessel milk supply opening, then a siphoning effect will occur in practice, and the effective column, i.e. the effective height difference, is the difference between a vertical position of the chamber, more accurately the chamber milk discharge opening, and a vertical position of the vessel milk supply opening.

[0015] The height of the chamber may be approximated, for example, from an average height of the teats of the herd, if desired of the breed. The height of the front level may be calculated from the measured amount of milk obtained and the cross section of the milking hose. The height of the vessel milk supply opening is a fixed height which has for example been measured beforehand.

[0016] It is noted here that, although an elevation height is determined in the abovementioned document US2020084994A1 , it is used to calculate the effect on the milk flow along the milk valve used therein more accurately. The effect on any transport vacuum is not suggested or explained in any way.

[0017] In particular embodiments, the milking device furthermore comprises a position detector for determining a position of the teat or of said cup milk discharge opening, wherein the control unit is configured to determine the elevation height ho on the basis of the measured position and a height position of said vessel milk supply opening. In this way, the control unit is able to determine the hydrostatic pressure of the milk column with an even greater degree of accuracy, and this has to be taken into account when determining the transport vacuum, which may thus play a part when setting the desired transport vacuum. In this case, the "desired transport vacuum" is the transport vacuum which effectively acts on the milk in the chamber.

[0018] The position of the cup milk discharge opening is the position where the milking hose connects to the milking cup, that is to say the chamber thereof. In an advantageous way, this opening is situated at a lowest position for the milk in the chamber, so that the chamber can be emptied in a satisfactory manner. But in any case, the cup milk discharge opening will be situated at the location of the connection of the milking hose to the milking cup, and the position of this connection may be determined by means of the position detector. For example, the position detector comprises an optical camera and image recognition for processing the camera images and recognizing said connection therein. Alternatively, it would for example also be possible to determine a position of the top of the bottom side of the milking cup, after which the control unit or position detector subtracts a known value from this position or adds a known value from this position, in each case obviously the height.

[0019] In embodiments, the milking device furthermore comprises a chamber milk level meter configured to measure a milk level of the milk in the chamber, wherein said parameter comprises said milk level. In this way, the control unit can further correct the transport vacuum. After all, the milk in the chamber will also exert a hydrostatic pressure which in this case actually assists the transport vacuum. In this case, it should however be noted that this hydrostatic pressure will not be very large in practice. Depending on the size / height of the chamber, the milk level may be, for example, at most 10 cm, and thus the maximum hydrostatic pressure of this milk is 1 kPa.

[0020] Mention has already been made above of a valve in the milking hose which is also known in the prior art for (partly) regulating the milk flow out of the chamber. A pressure drop will also occur across this valve which will depend on the position of this valve. Therefore, in embodiments, the milking hose comprises a controllable milk valve with an adjustable pass-through position, and a pressure drop meter for measuring a pressure drop across the milk valve, wherein the control unit is configured to adjust the transport vacuum Tv as a function of said pressure drop. In this case, "in the milking hose" comprises both directly in the chamber milk discharge opening and in the milking hose itself. It should be noted that both the milk valve and the transport vacuum have an effect on the discharge of milk from the chamber. Depending on what is desired, one or both may be used to realize these desires. For example, if a virtually constant milk level is desired in the chamber, it is possible to use a milk valve with a small pressure drop, but a limited control range, wherein the transport vacuum is only increased in case of very high flows of milk so as to be able to ensure that constant milk level. In most situations, a lower transport vacuum will then suffice, so that energy may be saved. In embodiments, the control unit is therefore configured to adjust the transport vacuum Vt as a function of said pass-through position of the control valve.

[0021] In embodiments, the milking device comprises an animal identification device for determining the identity of the dairy animal to be milked, wherein said parameter comprises the determined animal identity. For example, the control unit is configured to adjust the milking vacuum for each dairy animal, such as depending on the maximum milk flow to be expected. The vacuum device is then configured, for example, to adjust the transport vacuum as a function of that milking vacuum adjusted for each dairy animal.

[0022] The invention will be explained below in more detail by means of a nonlimiting exemplary embodiment, as well as the drawing, in which:

[0023] - Figure 1 shows a highly diagrammatic view of a milking device 1 according to the invention;

[0024] - Figure 2 shows a milking cup 5 of the milking device 1 according to the invention in detail;

[0025] - Figure 3 diagrammatically shows some details of another part of the milking device according to the invention; and

[0026] - Figure 4 diagrammatically shows the operation and advantages of the invention.

[0027] Figure 1 shows a highly diagrammatic view of a milking device 1 according to the invention. The milking device 1 here comprises a robot 2 with a robot arm 3 and a gripper 4, as well as a milking cup 5 and a vacuum device 6 with a pulsating line 7, a milking vacuum line 8 and a transport vacuum line 10 to a milk glass 11. Reference numeral 9 denotes a milking hose and reference numeral 12 denotes a control unit. A milk pump 14 pumps milk to the milk tank 15 via a milking line 13 or to the gutter 17 via the three-way valve 16. In addition, a part of a dairy animal 100 is shown, with teats 101 , and an ID-tag 102 which is legible by a tag reader 103.

[0028] The milking device 1 shown here is a robot milking device which is capable of milking a dairy animal 100, such as a cow, completely autonomously. The illustrated variant grabs milking cups 5 individually in order to attach them to the teats 101. Alternatively, the robot arm 3 without gripper carries all milking cups 5 in such a way that they are releasable, as is the case with the Astronaut® system of Lely Industries. However, the invention also applies to conventional milking devices without a robot 2, wherein a human being attaches the milking cups 5 to the teats 101. For the sake of clarity, only one milking cup 5 is shown here, with the actual number usually being four, or two, for example with devices for milking goats. The dairy animals 100 are provided with an ID tag 102 which serves to identify each of them. In robot milking devices, this ID tag 102 is readable by a tag reader 103, and in conventional milking devices it is either readable by a similar tag reader or readable by a human being. In this way, the control unit 12 can couple the dairy animal to a file coupled thereto and containing animal-related information. The control unit can then adjust the milking device 1 in accordance with this information.

[0029] The vacuum device 6 comprises at least one vacuum pump, and applies a vacuum to various vacuum lines, such as a pulsation vacuum to the pulsating line 7 which provides the pulsation vacuum known per se in the pulsation space of the milking cup 5. The pulsator which ensures that the pressure changes has not been shown in this case, but is well-known to the person skilled in the art. In addition, the vacuum device 6 applies a milking vacuum to the milking vacuum line 8, a milk transport vacuum to the transport vacuum line 10 and thus to the milk glass 11 , and furthermore to the milking hose 9. The milk of one milking operation is collected in the milk glass 11 . After the milking operation, the milk collected is pumped to the bulk milk tank 15 by the milk pump 14 via the milking line 13, or, if the milk does not meet the requirements for human consumption, is pumped into the gutter 17 or another destination via the three-way valve 16. In this case, the milk pump 14 is not particularly limited, and is, for example, a centrifugal pump. Sometimes, it is advantageous to use a pump with a self-priming function, such as a fixed volume pump, for example a bellows pump.

[0030] Figure 2 shows a milking cup 5 of the milking device 1 according to the invention in detail.

[0031] The milking cup 5 comprises a cup housing 20 and a teat lining 21 which surrounds a teat space 22 with a teat opening 23 and a cup milk discharge opening 24. A pulsation space 25 with a pulsation opening 26 is connected to the pulsating line 7. A chamber 29 is connected to the cup milk discharge opening 24 at a chamber milk supply opening 27 via a small connecting piece 28, surrounds a milk-collecting space 30, and has a chamber air discharge opening 31 and a chamber milk discharge opening 32, as well as a milk level meter 33 comprising electrodes 34 and a bottom electrode 35.

[0032] The milking vacuum line 8 is connected to the chamber air discharge opening 31 , and has a milking vacuum sensor 37. The milking hose 9 is connected to the chamber milk discharge opening 32, and has a controllable milk valve 39 for controlling the discharge of the milk 40, and a milk flow meter 41 for measuring this milk flow.

[0033] The milking cup 5 receives a teat in the teat space 22 via the teat opening 23. An alternating negative pressure is applied to the pulsation space 25 via the pulsating line 7 which causes the teat lining 21 to apply a pressure to the teat which changes as a function of pulsations and also closes off the teat from the milking vacuum.

[0034] The milking vacuum, which serves to milk milk from the teat, prevails in the teat space 22. The milking vacuum is provided to below the teat (not shown) via the milking vacuum line 8, the milk-collecting space 30 of the chamber 29, the chamber milk supply opening 27, the small connecting piece 28 and the cup milk discharge opening 24. It should be noted in this case that the milk, which exits the teat in gushes, will fill the cup milk discharge opening 24 for only a short time, and will thus also only block the direct connection between the milking vacuum line and the teat space temporarily. Usually, the milk obtained 40 is situated at the bottom of the milk-collecting space 29 of the chamber 30, and there is a direct open connection between the milking vacuum line 8 and the teat space 22. This means that the effective milking vacuum with which the teat is milked is very well controllable and in principle does not depend, or hardly, on the milk flow or milk gushes from the teat. By contrast, with conventional milking cups, the milking vacuum is provided via the same line which is used to discharge the milk obtained. This means that the milk obtained actually fills this line and consequently the vacuum provided does not act directly on the teat, which therefore means that the effective milking vacuum on the teat may vary to a lesser or greater extent, depending on the size of the milk flow from the teat. This variation makes it difficult or virtually impossible to adjust the teat-side vacuum in a satisfactory manner. With the milking device according to the present invention, however, this is readily possible. The (teat-side) milking vacuum can be measured for control purposes using the optional milking vacuum sensor 37.

[0035] The milk 40 collected at the bottom of the chamber is discharged under the action of a milk transport vacuum, which is provided via the milking hose 9. It should be noted that this milk transport vacuum has little, if any effect on the teat-side milking vacuum as long as there is sufficient milk 40 at the bottom of the milk-collecting space 39 to close off the chamber milk discharge opening 32. This milk level can be measured by means of the provided milk level meter 33. The latter measures, for example, the conductivity between each of the electrodes 34 and the bottom electrode 35. The highest electrode with a conductivity which indicates the presence of milk indicates the milk level. Incidentally, the milk level meter 33 may also be designed differently, such as with a series of photo-electrical cells and detectors, or with an (optical) transmission meter, etc. In this exemplary embodiment, the chamber 29 is shown as being dimensionally stable and connected to the cup housing 20 to form a single entity. This offers advantages with regard to protection of the sensors in the chamber, etc. However, it is also possible to position the chamber at a distance from the cup housing 20, for example by producing the small connecting piece 27 as a flexible hose, as long as the path of the milk after the cup milk discharge opening 24 does not ascend, i.e. is either partly horizontal, partly descending, or, and advantageously, continuously descends. In this way, the milk in the chamber may also actually drop, so that the milking vacuum can freely go to the teat space.

[0036] The removal of milk by optionally sucking off milk via the milking hose 9 is controlled by the position of the controllable, in particular proportional, valve 39. Incidentally, it is also possible to use an "on / off"-valve and allow it to determine the milk flow, for example using pulse width modulation. The milk flow through the milking hose 9 can be measured using the optional milk flow meter 41 .

[0037] Optionally, a pulsation vacuum sensor may be provided in the pulsating line 7 which is configured to measure the pulsation vacuum and forwarding this value to the vacuum device. In this way, the latter is able to set a correct pulsation vacuum. In addition, an optional transport vacuum sensor may also be provided in the milking device which is configured to measure the transport vacuum and passing this value on to the vacuum device. In principle, this transport vacuum sensor is not situated in the milking hose, but either at the top of the milk glass 11 or, for example, and in particular, in the transport vacuum line 10.

[0038] The milking vacuum sensor 37 is optionally provided for measuring the (teat-side) milking vacuum and passing this value on to the vacuum device, so that the latter can readjust the milking vacuum, if desired.

[0039] Figure 3 diagrammatically shows some details of another part of the milking device according to the invention, with the milk glass 11 , or the milk-collecting vessel, with the transport vacuum line 10 connected thereto at the top via the vessel air discharge opening 50, and the milking hose 9 connected via the vessel milk supply opening 51 . The vessel contains the milk obtained 52 which can be discharged via the milking line 13. Not shown are vessel milk supply openings for the other milking hoses, nor a valve keeping the vessel 11 closed during the milking operation.

[0040] The vessel milk supply openings 51 are situated virtually at the top, so that the milk can flow downward and out into the vessel 11 without encountering a counterpressure of milk 52. A transport vacuum prevails in the transport vacuum line 10 which likewise prevails in the vessel 11 via the vessel air discharge opening 50. This vacuum "pulls" on the milk in the milking hose 9, and thus transports it out of the milking cup 5 (not shown here) via the milking hose 9.

[0041] Figure 4 diagrammatically shows the operation and advantages of the invention by means of a detail of an exemplary embodiment of the milking device 1 according to the invention.

[0042] A milking cup 5 on a teat 101 of an udder 102 of a dairy animal 100 is shown (not to scale). Any similar components are denoted by the same reference numerals and this is the case in the entire drawing. Furthermore, reference numeral 54 denotes a pressure drop meter, and reference numeral 55 denotes a positioning camera.

[0043] In conclusion, a few different heights with respect to the floor surface 56 are indicated: hi is the height of the milk surface of the milk 40, h2 is the height of the vessel milk supply opening 51 , hs is the height of the base of the teat to which the milking cup 5 is attached, h4 is the height of the bottom side of the milking cup 5 / chamber 29, and hs is the height of the highest point of the milking hose 9.

[0044] According to the invention, it is advantageous to adjust the transport vacuum in the milking hose 9 to the set and also prevailing milking vacuum above the milk 40 in the chamber 29, which also prevails in the teat space. After all, the force with which the milk 40 is sucked out of the chamber 29 is partly determined by the difference between the milking vacuum above the milk, and the transport vacuum "below" the milk. And in turn this force has an effect on the speed at which the milk flows through the hose 9, which speed again has an effect on the drop in the milk level of the milk 40 in the chamber 29. In some embodiments, it is desirable to keep this milk level as constant as possible. Alternatively or additionally, the controllable valve 39 is controlled by the control unit in order to keep this milk level as constant as possible. However, it is furthermore the case that a pressure drop across this valve 39 will also occur, which may be assumed to be known with a known milk flow and valve position, for example from calibration measurements. However, if the milk flow is prone to significant variations, this pressure drop is much less clearly determined. In conclusion, it may be said that it is advantageous to allow the milk flow to proceed with as few unknown or still to be measured variables as possible. Another important variable is the intrinsic pressure difference between the transport vacuum and the milking vacuum. If this is substantially constant, it is possible to design in particular the control unit of the valve 39 to keep the milk level in the chamber 29 constant to be much more reliable and simple. It is therefore at least advantageous to adjust the transport vacuum to the milking vacuum since this is likewise readily controllable with the present milking device. It is even more advantageous if the pressure difference between the transport vacuum and the milking vacuum is substantially constant, such as for example 2 kPa, or 5 kPa, or any other value, for example between

[0045] I and 15 kPa. In this case, however, it is true that the transport vacuum which effectively acts on the milk 40 is influenced by a variety of factors.

[0046] The transport vacuum depends in the first instance on the (negative) pressure in the milk glass 11 , as applied via the transport vacuum line 10. When the milking hose 9 has then completely filled with milk and the latter flows into the milk glass

[0047] I I via the vessel milk supply opening 51 , the effective transport vacuum has reduced by the hydrostatic pressure of the milk, which is then pmiik*g*(h2 - hi).

[0048] In this case, hi may be determined by means of the milk level meter 33 in the chamber 29, as well as by means of the height hs of h4. The height hs is the height of the base of the teat to which the milking cup 5 is attached. This height may be determined, for example, at the start of the milking operation by means of the positioning camera 55, which is, for example, (also) configured to determine the teat position. The camera 55 is for example a 3D camera, a stereo camera or alternatively a laser detector, in each case as known in the prior art. The camera 55 is arranged, for example, on the robot arm of a milking robot or on a part of a milking stall (not shown) in which the dairy animal is milked. It is also possible, as is the case in this last example, for the camera 55 to constantly determine the position of the base of the teat, since this may change during milking. Alternatively or additionally, it is possible for the camera 55 to determine the position of the underside of the milking cup 5, and thus of the chamber 29, or of another characterizing part of the milking cup 5. Since the chamber 29 is preferably dimensionally stable, it suffices to determine the position of the milking cup 5 to also determine the position of the underside of the chamber 29, i.e. h4. If the chamber 29 is flexibly connected to the milking cup 5, the position of the chamber 29 itself will have to be determined, and hs is in principle less useful if at all. Incidentally, the height hs may alternatively also be determined, or approximated, by the robot arm while the milking cup 5 is being connected. After all, the control unit which actuates the actuators (not shown) for the robot arm will also record to which position these send the robot arm while connection takes place. Finally, in principle, the height h2 is a fixed value, and only has to be determined once.

[0049] In this case, it is important to point out that, in practice, the milk level in the chamber 29 will often only be a few centimetres, such as less than 10 cm. The share of the milk level in the hydrostatic pressure will then also be less than 1 kpa. In addition, if it is assumed that the control of the milk level can remain within, for example, 1 to 2 cm, this share will in addition vary 0.2 kPa at most. In the majority of cases, this is such a small variation that the milk level measurement for setting the transport vacuum can simply be omitted, or can be replaced by a fixed value of, for example, 5 cm, or 0.5 kPa. It should be noted that as long as the milk in the milking hose 9 has not yet reached the vessel milk supply opening 51 , the hydrostatic pressure of the milk will be different, and is determined by the height above the floor 56 of the front of the milk in the milking hose 9. This is difficult to determine, so that it is better to take the maximum height thereof, and that is hs. If the milking hose 9 is sufficiently stiff, this is also a value which is fixed in principle, and if the hose is (very) flexible, an estimate may be used. However, it should be noted that this value is no longer relevant once the milk flows into the milk glass 11 , due to the siphoning action which occurs then.

[0050] The described examples are not intended to be limiting. The scope of protection of the invention is determined by the attached claims.

Claims

CLAIMS1 . Milking device for milking a dairy animal with teats, comprising at least one milking cup to be attached to one of the teats, which milking cup comprises:- a cup housing,- a teat lining which is arranged in the cup housing and surrounds a teat space with a teat opening and a cup milk discharge opening, wherein a pulsation space with a pulsation opening is situated between the teat lining and the cup housing,- a chamber which is configured to receive the milk obtained and to separate milk and air, which chamber extends during said milking from the cup milk discharge opening in a fluid- connected manner, wherein said chamber comprises a milk supply opening which is in liquid communication with the cup milk discharge opening, and a chamber milk discharge opening, as well as a separate chamber air discharge opening which is situated above the chamber milk discharge opening during said milking operation, wherein the milking device furthermore comprises:- a control unit,- a milk-collecting vessel for temporarily accommodating the milk of one milking operation, with a vessel milk supply opening, a milking hose connected between the chamber milk discharge opening and the vessel milk supply opening, and a vessel air discharge opening,- a controllable vacuum device configured to apply a pulsation vacuum VPto the pulsation space via the pulsation opening, a milking vacuum Vm to the chamber via the chamber air discharge opening, and a transport vacuum Vt to the milk-collecting vessel and the milking hose via the vessel air discharge opening, wherein the vacuum device is configured for setting the transport vacuum Vt as a function of a milking-related parameter.

2. Milking device according to Claim 1 , wherein said parameter comprises said milking vacuum Vm to be provided during the milking operation.

3. Milking device according to Claim 2, wherein the control unit is configured to set the transport vacuum Vt equal to the milking vacuum Vm plus a predetermined pressure difference, in particular between 2 and 10 kPa, more particularly between 5 and 10 kPa.

4. Milking device according to Claim 1 , wherein said parameter comprises an elevation height ho of the milk obtained in the milking hose, in particular equal to pmiik*g*h0.

5. Milking device according to Claim 4, furthermore comprising a position detector for determining a position of the teat or of said cup milk discharge opening, wherein the control unit is configured to determine the elevation height ho on the basis of the measured position and a height position of said vessel milk supply opening.

6. Milking device according to one of the preceding claims, furthermore comprising a chamber milk level meter configured to measure a milk level of the milk in the chamber, wherein said parameter comprises said milk level.

7. Milking device according to one of the preceding claims, with the milking hose furthermore comprising a controllable milk valve with an adjustable pass-through position, and a pressure drop meter for measuring a pressure drop across the milk valve, wherein the control unit is configured to adjust the transport vacuum Tv as a function of said pressure drop.

8. Milking device according to Claim 7, wherein the control unit is configured to adjust the transport vacuum Vt as a function of said pass-through position of the control valve.

9. Milking device according to one of the preceding claims, comprising an animal identification device for determining the identity of the dairy animal to be milked, wherein said parameter comprises the determined animal identity.

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