Milking device

Abstract

There is provided a milking device (1) with milking cups (5). The milking cup comprises a cup housing (20) and a teat lining (21) which define a pulsation space (25) and a teat space (22) with a teat opening (23) and a cup milk discharge opening (24). The milking cup has a chamber (29) for milk / air separation which extends downwards from the cup milk discharge opening, and a chamber milk supply opening (27) and a chamber milk discharge opening (32), as well as a separate chamber air discharge opening (31) above the chamber milk discharge opening. The milking device furthermore has a milk-collecting vessel (11) for temporarily storing the milk of one milking operation, with a vessel milk supply opening (51) and a milking hose (9) which runs from the latter to the chamber milk discharge opening, and with a vessel air discharge opening (50), and a vacuum device for setting a pulsation vacuum Vp for the pulsation space, a milking vacuum Vm for the chamber, and a transport vacuum Vt for the milk-collecting vessel. In this case, it is true that Vp < Vm < Vt. Due to the milk / air separation in the chamber, the milking vacuum is readily controllable. As a result thereof, the pulsation vacuum may be selected to be smaller than or equal to the milking vacuum, as a result of which no ballooning of or vacuum leak occurs at the teat lining.

Description

[0001] Milking device

[0002] The present invention relates to a milking device for milking a dairy animal having teats during a milking operation comprising a pre-milking phase, a main milking phase and a post-milking phase, 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 separate milk and air, which chamber extends downwards during said milking from the cup milk discharge opening in a fluid-connected manner, wherein said chamber comprises a chamber 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 milk-collecting vessel configured to temporarily store the milk of one milking operation, with a vessel milk supply opening and a milking hose connected between the chamber milk discharge opening and the vessel milk supply opening, and with a vessel air discharge opening, a vacuum device configured to apply a pulsation vacuum VPto the pulsation space, a milking vacuum Vm to the chamber, and a transport vacuum Vt to the milk-collecting vessel.

[0003] Such a milking device is known from US2020084994A1 . This document does not give a detailed explanation regarding the setting of the various vacuum levels. In practice, it has been found that it is not always possible to perform the milking operation in a reliable, quick and animal-friendly way.

[0004] It is therefore an object of the present invention to provide a milking device of the above-described kind which can ensure a reliable, quick and animal-friendly milking operation.

[0005] To this end, the invention provides a milking device according to Claim 1 , wherein it is true that VP< Vm < Vt at least during the entire main milking phase.

[0006] The invention is based on the understanding that the m ilk / air separation, as known per se from US2020084994A1 , ensures that the milking vacuum in the chamber, and thus of the teat space directly connected thereto, is readily controllable and, if desired, very constant. This in itself already is a contrast with the customary milking cups, wherein the milking vacuum is a resultant of the milk transport vacuum applied to the milking hose and the current milk flow through this milking hose. After all, with a conventional milking cup both milk and air are discharged from the teat space via the same milking hose. This means that the effective, i.e. teat-side, milking vacuum can be much lower with a large milk flow than when there is no or only a small milk flow. In the latter case, there is after all in principle a direct connection between the teat space and the milking hose in which the transport vacuum prevails. The milking vacuum, at least the transport vacuum which eventually has to produce this milking vacuum in the teat space, is therefore adjusted to a value which is associated with an average milk flow. The pulsation vacuum cannot be selected to be excessively low, since this pulsation vacuum has to be able to open the teat lining for the milking stroke, even at a low milk flow, as is the case at the start or end of the milking operation. For this reason, the pulsation vacuum is always selected to be higher than the desired milking vacuum, for an average milk flow.

[0007] It is known per se from EP2252142B1 to lower the pulsation vacuum to below the milking vacuum when detecting bimodality in the milk flow, in order to prevent the milking cup from creeping up. The pulsation vacuum and the milking vacuum are subsequently gradually increased. However, in this case conventional milking cups were used, where the milking vacuum cannot be determined very accurately. In addition, it is in particular the case with bimodality (temporary drop in the milk flow during the transition from cistern milk to alveolar milk) anyway that the full vacuum prevails below the teat, and this vacuum is not lowered by the milk flow. According to the present invention, it is actually better to use a pulsation vacuum which is lower than the milking vacuum during the entire main milking phase.

[0008] The milking operation is divided into three phases, the pre-milking phase, the main milking phase and the post-milking phase. In the present invention, the premilking phase is understood to mean the phase in which pre-milk is collected and the milk flow commences, the main milking phase is the phase in which most milk is collected, around the peak milk flow, and the post-milking phase is the phase in which the milk flow clearly drops and usually the milking vacuum is reduced. In this case, the main milking phase can be selected more or less freely, but a definition which is commonly used is that the main milk flow is the period during which the milk flow is at least at a predetermined percentage of the maximum milk flow, such as at least 25% of the peak milk flow.

[0009] For the sake of clarity, it should be noted here that in this application "a higher vacuum" means "a higher difference with ambient pressure", in other words a lower absolute pressure. Furthermore, it will be clear that a pulsating line will have been provided from the vacuum device to the pulsation opening, a milking vacuum line to the chamber milk discharge opening, and a transport vacuum line to the vessel air-discharge opening. This transport vacuum is passed to the milking hose via the milk-collecting vessel.

[0010] However, this means that the effective milking vacuum in the teat space at a high milk flow is noticeably lower than the pulsation vacuum. If the milking vacuum is lower than the pulsation milking vacuum, this has adverse consequences for the milking operation. Firstly, the higher pulsation vacuum pulls the teat lining too much which consequently starts to balloon. As a result thereof, this teat lining adjoins the teat less well, and the teat may move inside the milking cup which is undesirable. It is also possible for air to leak out via the teat lining, namely from the head space, in the upper part of the milking cup. As a consequence, an excessive negative pressure will prevail there, which is undesirable and exerts a suction force on the upper part of the teat, where a ring of veins is situated. The negative effect of this negative pressure is that the ring of veins will swell up and the milk duct in the teat will generally be pinched off. As a result thereof, the milking operation is rendered more difficult and the teat is subjected to unnecessarily heavy loads.

[0011] The inventor has realized that the m ilk / air separation in the chamber of the milking cup according to the invention, and according to US2020089449A1 , which ensures a more controllable and, if desired, constant milking vacuum below the teat, is consequently also able to ensure an optimally adjusted pulsation vacuum. After all, precisely because the effective milking vacuum does not change, at least not much, due to variations in the milk flow, it is readily possible to adjust the pulsation vacuum thereto. According to the invention, this is carried out by selecting the pulsation vacuum VPto be smaller than or equal to the milking vacuum Vm. In this case, it should be noted that the teat itself, due to its volume and elasticity, as well as the properties of the teat lining itself, may ensure that even with a pulsation vacuum which is (slightly) smaller than the milking vacuum, the teat lining still opens during the milking stroke. It is important, however that this ensures that the teat lining stays well connected to the teat and no air is allowed to leak out.

[0012] Particular embodiments are described in the dependent claims, and in the following part of the description together with their advantages.

[0013] According to the invention, the chamber extends downwards during said milking in a fluid-connected manner from the cup milk discharge opening. It should be noted here that this means that the shape and orientation of the chamber is such that the chamber air discharge opening will remain above the chamber milk discharge opening during milking, and that the former will not be closed off by milk which has been collected in the chamber. The chamber is therefore substantially non-rising.

[0014] As has already been indicated above, the pulsation vacuum according to the invention is smaller than or equal to the milking vacuum, i.e. below the teat. In this case, it is true that "the pulsation vacuum" is the vacuum which prevails in the pulsation space during the b or suction phase of the pulsation. Obviously, during the d or rest phase, a (much) higher pressure / lower vacuum prevails, such as in particular atmospheric pressure. In particular, the vacuum device is configured in such a way that VP< Vm. In this way, it can be readily ensured that the teat lining always adjoins the teat in a satisfactory manner. For example, the vacuum device is adjusted in such a way that VP- Vm = a constant, with the constant being, for example, between 1 and 10 kPa, in particular between 2 and 5 kPa. In this range, the inherent elasticity of teat and teat lining is still sufficient to also ensure that the teat lining opens during the milking stroke. Here, all this depends on the properties of the material and the shape of the teat lining, and also slightly on the physical properties of the teats of the type of dairy animal to be milked.

[0015] The design of the chamber for collecting the milk for the m ilk / air separation, is not limited in any particular way, except for the fact that it extends downwards. For example, the chamber may be a flexible line part. Advantageously, however, the chamber is dimensionally stable and connected to the cup housing to form a single entity. The dimensional stability means, for example, that the shape does not change substantially during normal use, and that consequently there will be no undesirable pressure variations in the chamber. In addition, any components provided in the chamber, such as a sensor, are better protected against damage by, for example, a kick from the dairy animal. For example, the chamber has the same stiffness as the cup sleeve, and the chamber and the cup sleeve in particular are made from the same material, although other materials are of course also possible.

[0016] In embodiments, the milking device comprises one or more sensor devices configured to measure vacuum values of at least the pulsation vacuum VPand the milking vacuum Vm, wherein the vacuum device is configured to adjust at least the pulsation vacuum and / or the milking vacuum VM on the basis of the measured vacuum values. Even though it is possible, in principle, to control the milking device on the basis of expected vacuum values, in particular since few variations in the milking vacuum will occur due the m ilk / air separation in the chamber, the provision of said vacuum sensors and the ability of the control unit to readjust said vacuums will offer more and better possibilities to be able to quickly correct unexpected variations. In particular, the milking device also comprises a sensor for measuring the transport vacuum VT and the control unit is also configured to adjust the transport vacuum VT on the basis of the measured vacuum values. In this case, it is not necessary for the control unit to adjust any vacuum value on the basis of every other vacuum value.

[0017] In embodiments, the milking device comprises an animal identification device for determining the identity of the dairy animal to be milked, wherein the vacuum device is configured to set the pulsation vacuum and / or the milking vacuum as a function of the determined identity of the animal. This offers the possibility to adapt the milking operation to the dairy animal, which may be advantageous because not every dairy animal has the same demands with regard to the milking vacuum and optionally the pulsation vacuum. Thus, the values of one or more of these vacuums or the profile during the milking operation, or even during an individual pulsation may be adapted. Obviously, the condition that Vp < VM remains in place, but in the milking device according to the invention, with m ilk / air separation in the chamber, i.e. directly below the teat, in particular the milking vacuum, and partly as a result thereof the pulsation vacuum, are more readily controllable.

[0018] Milking device according to one of the preceding claims, wherein the vacuum device is configured to set the milking vacuum VM for each milking cup as a function of a parameter related to the milking of the teat of the dairy animal, in particular at least one of an absolute milking speed, a relative milking speed with respect to a, particularly from a historic point of view, maximum milking speed of the dairy animal, and a quantity of milk milked during the milking operation. As there will usually be differences between the teats of a dairy animal, such as between left and right, but for sure between the front side and the rear side, and because the teats will obviously not be milked exactly at the same time, it is desirable to be able to adjust the milking vacuum for each teat. Useful parameter values to control the latter are said parameters, although others are not excluded. A high absolute, or relative, milking speed offers the possibility of adjusting the milking vacuum. The milking vacuum may be increased, for example, because the dairy animal apparently quickly produces a significant amount of milk and can maybe be milked (even) more quickly, or the milking vacuum could conversely be reduced in order to lower the load on the teat since an acceptable milking speed will be achieved even at that reduced milking vacuum. This could play a part, for example, if the occupancy rate of the milking device is not high at that point in time, and there is sufficient time for a longer milking operation.

[0019] The invention will be explained in more detail below by means of a non- limiting exemplary embodiment, as well as the drawing, in which:

[0020] - Figure 1 shows a highly diagrammatic view of a milking device 1 according to the invention;

[0021] - Figure 2 shows a milking cup 5 of the milking device 1 according to the invention in detail; and

[0022] - Figure 3 diagrammatically shows some details of another part of the milking device according to the invention.

[0023] 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 pulsation 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 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.

[0024] 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 associated therewith and containing animal- related information. The control unit can then adjust the milking device 1 in accordance with this information.

[0025] 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.

[0026] Figure 2 shows a milking cup 5 of the milking device 1 according to the invention in detail.

[0027] 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.

[0028] 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 proportional milk valve 39 for adjusting the discharge of the milk 40, and a milk flow meter 41 for measuring this milk flow.

[0029] 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.

[0030] 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, from 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.

[0031] 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 detector, or with an (optical) transmission meter, etc.

[0032] 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 rise, 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.

[0033] The removal of milk by optionally sucking off milk via the milking hose 9 is regulated by the position of the 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 .

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] Figure 4 diagrammatically explains the advantages of the invention compared to the prior art, and to this end again shows a milking cup 5 of a milking device according to the invention. Identical components are denoted by the same reference numerals and this is the case in the entire drawing. In addition, reference numeral 2T denotes a ballooned teat lining 21 , and reference numeral 42 a head space.

[0039] In the prior art, values for the milking vacuum, the pulsation vacuum and the transport vacuum are selected which correspond as closely as possible with a quick milking operation which is as animal-friendly as possible. However, first and foremost the milking vacuum cannot be adjusted separately from the transport vacuum. The milking vacuum is the resultant of the transport vacuum minus the reduction in the vacuum resulting from the inflow of the milk in the milking cup. Teat-side, that is to say directly below the teat, the real milking vacuum may therefore vary significantly. By contrast, the pulsation vacuum is constant, that is to say is not actively controlled on the basis of the milk flow or the current teat-side milking vacuum. In principle, the pulsation vacuum should always ensure that the teat lining can be open, even if there is no milk flow (yet) or only a small milk flow. For this reason, the pulsation vacuum has to be in the vicinity of the highest set transport vacuum in the prior art. In a concrete practical example, the Astronaut® A5 by Lely Industries, the set system vacuum is, for example, 42 kPa, at least a value between 32 kPa and 42 kPa, according to ISO standards. Therefore, the milking vacuum is in this case at most 42 kPa, but can become much lower. On average, the effective, teat-side milking vacuum during the milking of a cow with an average milk flow has been found to be approximately 38 kPa. It should be noted here that this milking vacuum is not set directly, but is only the result of the set system vacuum in combination with the effects of the milk gushes. This value of 38 kPa is therefore only an average value for all kinds of values of the milk flow: with a milk flow which has not yet commenced, or is low for another reason, the milking vacuum is higher, as much as the set system vacuum of 42 kPa. If, by contrast, the milk flow is very high, the teat-side milking vacuum may drop sharply, to as little as 30 kPa. However, the pulsation vacuum always has to ensure that the teat lining can open, and must therefore not deviate too much from the highest occurring milking vacuum, in this case not 38 kPa, but the system vacuum of 42 kPa.

[0040] The result of all this is that the pulsation vacuum is often higher than the teat-side milking vacuum, and sometimes by a significant amount. This means that the teat lining balloons outwardly to a greater or lesser extent, that is to say away from the teat. This is illustrated in Figure 4 by means of the dashed lines of the ballooned teat lining 2T. This in turn results in the sealing between the teat and the teat lining leaving something to be desired, and air may leak out from the head space 42 to the teat space 22. Thus, there will be an undesirable excessive 'head vacuum' in the head space 42, which may cause the veins at the base of the teat to swell, thereby adversely impacting the milking operation, and which may also negatively affect teat health.

[0041] With the milking device according to the present invention, this negative effect does not, or hardly, occur, since the teat-side milking vacuum can be controlled much better. The reason for this is that milk / air separation already occurs in the milkcollecting space of the chamber, as a result of which the milk is situated on the bottom and only air (that is to say a "vacuum") is present in the space above. The desired milking vacuum is set via the chamber air discharge opening 31 which opens out into this space, so that it also prevails teat-side, virtually irrespective of the milk flow. This in turn makes it easy to actively adapt the pulsation vacuum to the teat-side milking vacuum, and in particular makes it easy to ensure that this pulsation vacuum will in principle always be smaller than or equal to the teat-side milking vacuum during the milking operation, so that the sealing of the teat lining on the teat is ensured. In particular, the pulsation vacuum is in each case (substantially) equal to the milking vacuum, so that the teat lining in principle always remains abutting and can still move as freely as possible. However, it is also possible to select the pulsation vacuum to be slightly lower than the milking vacuum, for example 2 kPa lower, in order to make the teat lining 13 adjoin the teat 101 more strongly.

[0042] Effectively, the pulsation vacuum can always be adapted to the demands of the milking operation. After all, the desired milking vacuum to be set can always vary during a milking operation, according to any regulation known in the prior art. The pulsation vacuum can then in each case be adapted thereto, for example by the same amount, by a constant difference, or whatever. It is also conceivable to vary pressure exerted on the teat 101 by the teat lining 13 during the milking operation as well, or as a function of the demands of the dairy animal. It is then very easy to vary the pulsation pressure accordingly as a function of the milking vacuum.

[0043] For the sake of clarity, it should be noted here that in this application a value for a vacuum is intended to mean the value of the difference with atmospheric pressure. For example, a "vacuum of kPa" stands for a pressure which is 42 kPa lower than the atmospheric (ambient) pressure. Likewise, a vacuum which is higher than another vacuum is thus a differential pressure which is greater than the other differential pressure. In that case, the absolute pressure is therefore lower than the other absolute pressure.

[0044] Incidentally, the milking device according to the invention also makes it possible to optimize the milking vacuum for the dairy animal, due to the fact that the desired value can actually be set in a stable manner. This desired value may vary from dairy animal to dairy animal and may be set, for example, after the ID tag of the animal has been read, and the control unit has looked for an associated value in a memory. The milking vacuum to be provided by the vacuum device may furthermore be set by the control unit as a function of a value related to the milking operation, such as the milking speed, i.e. the milk flow. This may be done in an absolute sense or in a relative sense, being a percentage of the historic maximum value of this milk flow. Some dairy animals benefit from a higher milking vacuum if the milk flow is higher, whereas with other dairy animals this makes no difference or even results in negative effects. Also, the milking speed during a milking operation varies and the milking vacuum can be adapted to such a variation of the milk flow, for example depending on an animal-dependent profile. In this case, it is furthermore possible to adjust the milking vacuum to the amount of milk obtained during the milking operation. This amount is an indication of the progress of the milking operation, and thus of the phase of the milking operation, such as starting phase, plateau phase or finish milking phase. Depending on the phase, the control unit may set an adjusted milking vacuum. It goes without saying that all the abovementioned vacuum settings may apply for each teat individually. 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 having teats during a milking operation comprising a pre-milking phase, a main milking phase and a post-milking phase, 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 separate milk and air, which chamber extends downwards during said milking from the cup milk discharge opening in a fluid-connected manner, wherein said chamber comprises a chamber 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 milk-collecting vessel configured to temporarily store the milk of one milking operation, with a vessel milk supply opening and a milking hose connected between the chamber milk discharge opening and the vessel milk supply opening, and with a vessel air discharge opening, and- a vacuum device configured to apply a pulsation vacuum VPto the pulsation space, a milking vacuum Vm to the chamber, and a transport vacuum Vt to the milk-collecting vessel, wherein it is true that VP< Vm < Vt at least during the entire main milking phase.

2. Milking device according to Claim 1 , wherein the vacuum device is configured so that VP< Vm.

3. Milking device according to one of the preceding claims, wherein the chamber is dimensionally stable and connected to the cup housing to form a single entity.

4. Milking device according to one of the preceding claims, comprising one or more sensor devices configured to measure vacuum values of at least the pulsation vacuum VPand the milking vacuum Vm, in particular also of the transport vacuum VT, wherein the vacuum device is configured to adjust at least the pulsation vacuum and / or the milking vacuum VM, in particular also the transport vacuum VT, on the basis of themeasured vacuum values.

5. 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 the vacuum device is configured to set the pulsation vacuum and / or the milking vacuum as a function of the determined identity of the animal.

6. Milking device according to one of the preceding claims, wherein the vacuum device is configured to set the milking vacuum VM for each milking cup as a function of a parameter related to the milking of the teat of the dairy animal, in particular at least one of an absolute milking speed, a relative milking speed with respect to a, particularly from a historic point of view, maximum milking speed of the dairy animal, and a quantity of milk milked during the milking operation.

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