A milking system with a plurality of milking devices and a vacuum system

Abstract

In a milking system (100), a vacuum system (110) is used which comprises a pipe system (111) with a vacuum supply line (113) and a pump connecting line (114), wherein the milking devices (101) are connected to the vacuum supply line. The vacuum system furthermore comprises at least three vacuum pumping devices (112) which are connected to the pump connecting line and which each comprise a vacuum pump (130). At least two of the vacuum pumping devices also comprise a liquid separation device (140) which is configured to extract liquid from the vacuum system, while at least one of the vacuum pumping devices is without such a liquid separation device. Controlling the vacuum system comprises ensuring that the vacuum pump is always in the active state in at least one of the vacuum pumping devices with a liquid separation device when the vacuum system is in operation, so that active dehumidification of the vacuum system always takes place despite the fact that not all vacuum pumping devices comprise a liquid separation device.

Description

[0001] A milking system with a plurality of milking devices and a vacuum system

[0002] The invention relates to a milking system comprising a plurality of milking devices for milking dairy animals; a vacuum system for producing a underpressure in the milking devices; and a control unit for controlling at least the vacuum system; wherein the vacuum system comprises a pipe system with a vacuum supply line and a pump connecting line which is in fluid communication with the vacuum supply line, wherein the milking devices are connected to the vacuum supply line, and wherein the vacuum system comprises at least three vacuum pumping devices which are connected to the pump connecting line; and wherein each of the vacuum pumping devices comprises a vacuum pump and the control unit is configured to set an active state or an inactive state of the vacuum pump.

[0003] The invention also relates to a method for controlling a vacuum system for producing a underpressure in a plurality of milking devices for milking dairy animals; wherein the vacuum system comprises a pipe system with a vacuum supply line and a pump connecting line which is in fluid communication with the vacuum supply line, wherein the milking devices are connected to the vacuum supply line, and wherein the vacuum system comprises at least three vacuum pumping devices which are connected to the pump connecting line; and wherein each of the vacuum pumping devices comprises a vacuum pump whose active state or inactive state can be set. The method may in principle be carried out by an operator. In particular, it is carried out by means of a control device which is configured for controlling the vacuum device. In this way, the method can easily be automated.

[0004] The use of a vacuum system in a milking system is generally known. NL- 1020785-C2 discloses a device for milking animals, which device is provided with at least two milking robots, wherein each milking robot is configured to automatically attach at least one milking cup to a teat of an animal, and wherein every milking robot is provided with a milking vacuum unit for producing a milking vacuum for milking an animal. The device is provided with a common ring line and with an adjustable, central vacuum system for applying a vacuum to the common ring line, wherein every milking vacuum unit is connected to the ring line via a passage.

[0005] WO-2019 / 103606-A1 discloses a milking system with a plurality of milking devices for milking dairy animals, a vacuum system for underpressure for milking and / or pulsation in the plurality of milking devices, and a control unit for at least the vacuum system. The vacuum system comprises N vacuum pumps of substantially identical capacity with N > 3. The milking devices may be milking robots, and may each have a connection for a milking vacuum and a connection for a pulsation vacuum.

[0006] WO-2019 / 177516-A1 discloses a milking system which comprises a main vacuum line and a vacuum pump arrangement with at least two vacuum pumping devices. The vacuum pumping devices are used to maintain a system vacuum in the main vacuum line. Each of the vacuum pumping devices comprises a vacuum pump, a vacuum tank which is connected to the vacuum pump by an intermediate line, and an inlet line which connects the vacuum tank to the main vacuum line. Furthermore, each of the vacuum pumping devices has a liquid outlet which extends from the vacuum tank and which comprises an outlet valve. In addition, each of the vacuum pumping devices comprises a shut-off valve on the inlet line. This shut-off valve is configured to close off the inlet line automatically when the vacuum pump has stopped.

[0007] It is possible to configure the outlet valve in such a way that it automatically opens the liquid outlet when the pump has stopped and the shut-off valve has been closed. Thus, the outlet valve may be configured to initiate the automatic discharge of liquid from the vacuum tank, in particular if a vacuum is no longer being applied to the vacuum tank and at least if the vacuum tank is at atmospheric pressure. When the pump has stopped in one or more vacuum pumping devices and liquid is being discharged from the vacuum tank, the other vacuum pumping devices maintain the system vacuum. The outlet valve may furthermore be configured to close off the liquid outlet automatically if the pump is restarted in a vacuum pumping device and causes the pressure in the vacuum tank to change.

[0008] The fact that liquid can reach a vacuum system of a milking system is connected to the fact that milk flows and streams of other liquids, such as cleaning liquids, are present in the milking system. From the point of view of hygiene and in order to obstruct the operation of the vacuum system as little as possible, it is important that liquid is collected at a defined position in the vacuum pumping devices, and also that collected liquid is regularly released from the vacuum pumping devices.

[0009] It is an object of the invention to provide a milking system with a plurality of milking devices and a vacuum system, wherein the vacuum system comprises at least three vacuum pumping devices, and wherein liquid can be removed from the vacuum system to a sufficient degree while making more efficient use than in conventional situations of the pumping capacity of the vacuum pumps of the vacuum pumping devices.

[0010] The object of the invention is achieved in that the invention provides a new arrangement for a vacuum device for use in a milking system with a plurality of milking devices, and also provides a control unit for the vacuum device according to this new arrangement. In particular, the invention provides a milking system comprising: a plurality of milking devices for milking dairy animals; a vacuum system for producing a underpressure in the milking devices; and a control unit for controlling at least the vacuum system; wherein the vacuum system comprises a pipe system with a vacuum supply line and a pump connecting line which is in fluid communication with the vacuum supply line, wherein the milking devices are connected to the vacuum supply line, and wherein the vacuum system comprises at least three vacuum pumping devices which are connected to the pump connecting line; wherein each of the vacuum pumping devices comprises a vacuum pump and the control unit is configured to set an active state or an inactive state of the vacuum pump; wherein at least two of the vacuum pumping devices furthermore comprise a liquid separation device which is configured to extract liquid from the vacuum system, and that is situated at a position between the vacuum pump and the pump connecting line, while at least one of the vacuum pumping devices is without such a liquid separation device; and wherein the control unit is configured such that when the vacuum system is in operation, the vacuum pump of at least one of the vacuum pumping devices with a liquid separation device is always in the active state.

[0011] The invention furthermore provides a method for controlling a vacuum system for producing a underpressure in a plurality of milking devices for milking dairy animals; wherein the vacuum system comprises a pipe system with a vacuum supply line and a pump connecting line which is in fluid communication with the vacuum supply line, wherein the milking devices are connected to the vacuum supply line, and wherein the vacuum system comprises at least three vacuum pumping devices which are connected to the pump connecting line; wherein each of the vacuum pumping devices comprises a vacuum pump whose active state or inactive state can be set; and wherein at least two of the vacuum pumping devices furthermore comprise a liquid separation device which is configured to extract liquid from the vacuum system, and which is situated in a position between the vacuum pump and the pump connecting line, whereas at least one of the vacuum pumping devices is without such a liquid separation device; wherein the method comprises the following: ensuring that the vacuum pump of at least one of the vacuum pumping devices with a liquid separation device is always in the active state when the vacuum system is in operation.

[0012] According to the invention, a vacuum system with at least three vacuum pumping devices is provided, in which the vacuum pumping devices are connected to a common pump connecting line, but in which not all vacuum pumping devices comprise a liquid separation device. It is an insight of the invention that there are practical possibilities to design a vacuum system in such a way that all the liquid which reaches the pump connecting line on account of the underpressure can be discharged adequately without the need for a liquid separation device to be present in every vacuum pumping device. The number of vacuum pumping devices comprising a liquid separation device is at least two, and preferably exactly two. These two vacuum pumping devices are controlled in such a way that the vacuum pump in at least one of the vacuum pumping devices is always in the active state when the vacuum system is in operation. This ensures that the functionality of collecting liquid at a defined position is always present. If the vacuum pump of one of the vacuum pumping devices with a liquid separation device is in the inactive state, for example because it is time to empty the liquid separation device of the respective vacuum pumping device, or because the vacuum pump has to be cleaned, maintained or repaired, there is always at least one other vacuum pumping device with a liquid separation device whose vacuum pump is in the active state.

[0013] From an energy point of view, it is disadvantageous to use a liquid separation device in a vacuum pumping device. It is therefore advantageous that, according to the invention, not all vacuum pumping devices are equipped with a liquid separation device since this makes it possible to produce the underpressure more efficiently than in a conventional situation in which all vacuum pumping devices do have a liquid separation device.

[0014] In a practical embodiment of the milking system according to the invention, the vacuum pumping devices with a liquid separation device are connected to a portion of the pump connecting line that is situated further from the vacuum supply line than a portion of the pump connecting line to which the at least one vacuum pumping device without a liquid separation device is connected. In this embodiment, a portion of the pump connecting line to which the at least one vacuum pumping device without a liquid separation device is connected is within the operating area of the vacuum pumping devices with a liquid separation device. It is furthermore practical if the vacuum pumping devices with a liquid separation device are connected to a side of the pump connecting line which is a bottom side of the pump connecting line when the vacuum system is in operation, and the at least one vacuum pumping device without a liquid separation device is connected to a side of the pump connecting line which is a top side of the pump connecting line when the vacuum system is in operation. On account of the force of gravity, liquid in the pump connecting line will mainly accumulate in the bottom regions of the pump connecting line, so that the risk of liquid reaching a liquid-separation device-less vacuum pumping device is additionally reduced if the latter is connected to a top side of the pump connecting line. In practical terms, liquid will always reach one of the vacuum pumping devices with a liquid separation device on account of a combination of the force of gravity and the underpressure that this vacuum pumping device produces.

[0015] It is possible for the vacuum pumping devices with a liquid separation device to be connected to the pump connecting line at a common position. This prevents the liquid from the pump connecting line from substantially ending up at only one of the vacuum pumping devices, namely the vacuum pumping device which is in the most upstream position and which is therefore situated furthest to the front in the direction in which the liquid moves through the pump connecting line on account of the vacuum.

[0016] In the context of the invention, any suitable type of liquid separation device may be used. It may be advantageous if the liquid separation device comprises a liquid store with a discharge element which is configured to close as a result of underpressure and to open as the pressure increases towards atmospheric pressure, so that discharge of stored liquid from the liquid store via the discharge element becomes possible. In this case, no active controlling action is required to render discharge of liquid from the liquid separation device possible after the vacuum pump of a vacuum pumping device with a liquid separation device has been stopped. Said discharge element may be, for example, a valve or a diaphragm.

[0017] It is advantageous if each of the vacuum pumping devices is connected to the pump connecting line via a valve. The control unit may be configured to set an open state or a closed state of the valve. In such a case, it is possible to disconnect a vacuum pumping device from the pump connecting line at any desired moment, which offers maximum flexibility when using the vacuum system. Alternatively, the valve is not actively driven, but is configured to automatically be in an open state or a closed state on account of a pressure difference across the valve. In this case, the valve may be provided with, for example, a ball as closing element, in which case the ball may be under the effect of a spring mechanism.

[0018] In accordance with that which is known per se, the vacuum system may comprise a sensor unit which is operationally connected to the control unit for detecting a momentary value of the underpressure in the pipe system. Detecting a momentary momentary value of the underpressure in the pipe system may be a step in a process of ensuring that a preset value of the underpressure prevails in the pipe system when the vacuum system is in operation. The control unit may be configured to carry out this process. In this case, it may be advantageous in each case to minimize the number of vacuum pumps in the active state. This may be achieved by running the vacuum pumps at maximum power as much as possible, and running only one vacuum pump at reduced power, in order thus to end up with an appropriate total power for producing the underpressure. It is possible, for example, for the vacuum pumps of the respective vacuum pumping devices to be configured to produce a vacuum on the basis of a movement, wherein the control unit is configured to vary a speed of the movement in a vacuum pump in the active state so as to vary the power at which the vacuum pump operates. It may be that this results in the speed of the movement in at most one vacuum pump in the active state being lower than a maximum speed during use of the vacuum system with at least two vacuum pumps in the active state, whereas the speed of the movement in the at least one other vacuum pump in the active state is the maximum speed.

[0019] The invention will be explained below with reference to the figures which are generally diagrammatic in nature and relate to non-limiting exemplary embodiments of a milking system and components thereof, wherein identical reference numerals denote identical or similar components, and wherein:

[0020] Figure 1 shows a diagrammatic representation of components of the milking system, in particular a number of milking devices for milking dairy animals and a vacuum system for producing a underpressure in the milking devices;

[0021] Figure 2 shows a diagrammatic view of a portion of the vacuum system;

[0022] Figure 3 shows a graph of an example of a rotary speed of vacuum pumps of the vacuum system over time during start-up of the vacuum system; and

[0023] Figure 4 shows a graph of a set underpressure in a pipe system of the vacuum system over time during start-up of the vacuum system, which graph is related to the graph from Figure 3.

[0024] Figure 1 is a diagrammatic representation of components of a milking system 100, in particular a number of milking devices 101 for milking dairy animals and a vacuum system 110 for producing a underpressure in the milking devices 101. Three milking devices 101 are shown in Figure 1 by way of example, but this does not alter the fact that the number of milking devices 101 is at least two and that the number of milking devices 101 may be significantly greater than three.

[0025] The milking devices 101 serve for milking dairy animals, such as cows, and may be automatic milking robots where the dairy animals can enter and exit independently. In order to function, the milking devices 101 use a vacuum. With this in mind, the milking system 100 comprises said vacuum system 110. The vacuum system 110 comprises a pipe system 111 and a number of vacuum pumping devices 112, wherein the pipe system 111 comprises a vacuum supply line 113 and a pump connecting line 114 which is in fluid communication with the vacuum supply line 113. The milking devices 101 are connected to the vacuum supply line 113, whereas the vacuum pumping devices 112 are connected to the pump connecting line 114. In the illustrated example, the number of pumping devices 112 is six, but this does not alter the fact that the number of pumping devices 112 is at least three and that the number of pumping devices 112 may optionally be greater than six.

[0026] Each of the vacuum pumping devices 112 comprises a vacuum pump 130 whose active state or inactive state can be set. To this end, the milking system 100 comprises a control unit 120 which at least serves to control the vacuum system 110. The vacuum pumps 130 of the vacuum system 100 may be identical to one another, but it is also possible for one or more different types of vacuum pumps 130 to be used in the vacuum system 100, wherein optionally a construction of various types of vacuum pumps 130 may be identical while a dimensioning of various types of vacuum pumps 130 may be different, so that a pump capacity differs. The vacuum pumps 130 may be vacuum pumps which are known per se and which are configured to produce a vacuum based on a movement, such as vacuum pumps with a rotatable impeller or vacuum pumps with a piston / cylinder device. Figure 2 shows that the vacuum pumps 130 are situated a certain distance apart in a frame 131.

[0027] Each of the vacuum pumps 130 is connected to the pump connecting line 114 via a pump line 115 which contains a valve 116. The control unit 120 is configured to set an open state or a closed state of the valve 116 and thus to disconnect a vacuum pumping device 112 from the pump connecting line 114 or to connect it to the pump connecting line 114. Furthermore, in the illustrated example, two of the six vacuum pumping devices 112 comprise a liquid separation device 140 for extracting liquid from the vacuum system 110, wherein the liquid separation devices 140 form a barrier, as it were, between milk / liquid, in particular in the pipe system 111 of the vacuum system 110 on the one hand and the vacuum pumps 130 of the vacuum system 110 on the other hand. In the context of the invention, any suitable type of liquid separation device 140 may be used. It is possible, for example, for the liquid separation device 140 to comprise a liquid store 141 with a discharge element 142 which is configured to close as a result of underpressure and to open as the pressure increases towards atmospheric pressure, so that discharge of stored liquid from the liquid store 141 via the discharge element 142 becomes possible.

[0028] In the illustrated example, the two vacuum pumping devices 112 with a liquid separation device 140 are situated in a rearmost position with respect to the vacuum pumping devices 112 without a liquid separation device 140 in a direction downstream of the vacuum supply line 113 and the milking devices 101 connected thereto. The two vacuum pumping devices 112 with a liquid separation device 140 are connected to the pump connecting line 114 at a common position 117, whereas the vacuum pumping devices 112 without a liquid separation device 140 are each connected to the pump connecting line 114 at a different position. The common position 117 at which the vacuum pumping devices 112 with a liquid separation device 140 are connected to the pump connecting line 114 is situated on a bottom side of the pump connecting line 114, whereas the positions at which the vacuum pumping devices 112 without a liquid separation device 140 are connected to the pump connecting line 114 are situated on a top side of the pump connecting line 114. This makes it possible to collect liquid from the entire pump connecting line 114, and makes it practically impossible for liquid to reach the vacuum pumping devices 112 without a liquid separation device 140, because the sucking action of the underpressure which is produced by the vacuum pumping devices 112 is insufficient to overcome the action of the force of gravity on the liquid. On the other hand, it is the case that, on account of the underpressure, liquid can very easily be moved across a lowest portion of the pump connecting line 114 to the position 117 at which the vacuum pumping devices 112 with a liquid separation device 140 are connected to the pump connecting line 114. With the costs of the vacuum system 110, the costs of using the vacuum system 110, and the space which the vacuum system 110 takes up in mind, it is an advantageous insight of the invention that it is not necessary for every vacuum pumping device 112 to comprise a liquid separation device 140, and that a configuration of the vacuum system 110 is possible in which the water separation function is realised completely using only a limited number of vacuum pumping devices 112 with a liquid separation device 140. Using fewer liquid separation devices 140 makes it possible to use the total pumping capacity of the vacuum system 110 more efficiently.

[0029] In the context of the invention, the number two for the number of vacuum pumping devices 112 with a liquid separation device 140 is a minimum number. Furthermore, the vacuum system 110 always contains at least one vacuum pumping device 112 without a liquid separation device 140. With at least two vacuum pumping devices 112 with a liquid separation device 140, it is always possible for the vacuum pump 130 of a vacuum pumping device 112 with a liquid separation device 140 to be in the inactive state without this cancelling out the functionality of collecting liquid in the vacuum system 110. In this way, it is possible to clean, repair or replace the vacuum pump 130 or another component of a vacuum pumping device 112 with a liquid separation device 140 without the entire vacuum system 110 having to be closed down. In case it is necessary to switch the downstream vacuum pump 130 to the inactive state in order to empty a liquid separation device 140, it is also practical if there is another vacuum pumping device 112 with a liquid separation device 140 which may be active in this situation so as to continue the function of collecting liquid in the vacuum system 110. The control unit 120 determines whether the vacuum pump 130 of one or both of the vacuum pumping devices 112 with a liquid separation device 140 is in the active state, whereas the control unit 120 controls the vacuum system 110 so as to satisfy the condition that the vacuum pump 130 of both the vacuum pumping devices 112 with a liquid separation device 140 must never be in the inactive state. In other words, the control unit 120 is configured in such a way that the vacuum pump 130 of at least one of the vacuum pumping devices 112 with a liquid separation device 140 is always in the active state while the vacuum system 110 is in operation.

[0030] As has been indicated above, producing a underpressure in the milking devices 101 is a primary function of the vacuum system 110. Another condition which applies to controlling the vacuum system 110 is to ensure that the underpressure in the pipe system 111 is at a preset value when the vacuum system 110 is in operation. In general, it is true that when there is a greater demand by the milking devices 101 for vacuum capacity, more pumping capacity has to be deployed than is the case when there is less demand for vacuum capacity in order to maintain the preset value of the underpressure. In practical terms, controlling the underpressure comprises measuring a momentary value of the underpressure and comparing the measured momentary value with the preset value. The vacuum system 110 then also comprises a sensor unit 121 which is operationally connected to the control unit 120 in order to detect a momentary value of the underpressure in the pipe system 111. The sensor unit 121 may comprise, for example, one or more vacuum sensors which are configured to output a signal which is representative of a measured value of the underpressure to the control unit 120. In order to prevent the underpressure from becoming excessive, various safety measures may be applied. In this context, the use of a vacuum limiter 122 is illustrated here by way of example.

[0031] The graphs from Figures 3 and 4 relate to an exemplary situation of starting up the vacuum system 110, wherein the graph from Figure 3 shows a rotary speed of vacuum pumps 130 plotted out against time, and wherein the graph from Figure 4 shows a set underpressure in the pipe system 111 plotted out against time. The starting points with this exemplary situation are that the vacuum pumps 130 are identical to each other, that for each of the vacuum pumps 130, the speed of a rotary movement determines the pumping capacity used, that this speed is variable, and that this speed is set by the control unit 120. In Figure 3, a line for a first vacuum pump 130 is denoted by the reference numeral 1 , a line for a second vacuum pump 130 is denoted by the reference numeral 2, a line for a third vacuum pump 130 is denoted by the reference numeral 3, a line for a fourth vacuum pump 130 is denoted by the reference numeral 4, a line for a fifth vacuum pump 130 is denoted by the reference numeral 5, and a line for a sixth vacuum pump 130 is denoted by the reference numeral 6.

[0032] Figure 3 firstly shows that the rotary speed of a first vacuum pump 130 increases, and Figure 4 shows that this is connected to an increasing set underpressure. This first vacuum pump 130 forms part of a vacuum pumping device 112 with a liquid separation device 140. The rotary speed of the first vacuum pump 130 increases until a maximum rotary speed of the vacuum pump 130 is reached. At that point in time, a second vacuum pump 130 is switched on. The second vacuum pump 130 starts from a minimum rotary speed, and the rotary speed of the first vacuum pump 130 initially decreases in order to reach a total rotary speed which has been set by the control unit 120. Thereafter, the rotary speed of the first vacuum pump 130 increases again until the maximum rotary speed is reached. From that point in time, the rotary speed of the second vacuum pump 130 increases until the maximum rotary speed is reached. In this way, a further gradual increase in the set underpressure is followed. The described procedure is repeated when a third vacuum pump 130, a fourth vacuum pump 130 and a fifth vacuum pump 130 are added. Lastly, a sixth vacuum pump 130 is switched on. In the illustrated example, reaching a preset value P of the underpressure is related to a situation in which the rotary speed of the sixth vacuum pump 130 is still the minimum rotary speed and the rotary speed of the fifth vacuum pump 130 increases to the maximum rotary speed. An example of the preset value P of the underpressure is 500 hPa. An example of the threshold value of the underpressure which is set by means of the vacuum limiter 122 is 600 hPa. An example of the minimum rotary speed of the vacuum pump 130 is 500 revolutions per minute, and an example of the maximum rotary speed of the vacuum pump 130 is 2,000 revolutions per minute.

[0033] Once the vacuum system 110 has been started up, the pumping capacity which is required to maintain the preset value P for the underpressure may vary, in particular if the demand for vacuum capacity of the milking devices 101 varies. The number of milking devices 101 which require a vacuum certainly does not have to remain the same all the time. Thus, sometimes more milking devices 101 are actually used for milking an animal, sometimes fewer. For example, a cleaning process may be taking place in one or more milking devices 101 instead of a milking process.

[0034] When controlling the vacuum system 110, the control unit 120 may use various starting points. Thus, the control unit 120 may be configured to minimalize the number of vacuum pumps 130 in the active state. In this case, the control unit 120 may be configured to distribute a required total rotary speed over as few as possible vacuum pumps 130 by making vacuum pumps 130 work at the maximum rotary speed and by setting the rotary speed of one vacuum pump 130 to be lower and varying this rotary speed until an additional vacuum pump 130 is switched on when the demand for vacuum capacity increases or a vacuum pump 130 is switched off when the demand for vacuum capacity decreases. The control unit 130 may also be configured in such a way that, when a vacuum pump 130 can be switched off, it chooses a vacuum pump 130 which has been working the longest at that point in time. In this way, it is possible to ensure that the vacuum pumps 130 are being used more or less to the same degree over time and the wear of the vacuum pumps 130 will consequently be more or less identical. It may also be the case that one vacuum pump 130 is always kept in an inactive state, so that there is always a reserve pump in case another vacuum pump 130 fails unexpectedly. In all this, the one thing that should be prioritized is the abovementioned condition that at least one vacuum pump 130 of the vacuum pumping devices 112 with a liquid separation device 140 must be active when the vacuum system 110 is in operation, so that active dehumidification of the vacuum system 110 is always possible. If the vacuum system 110 has been inactive and is switched on again, a vacuum pump 130 of a vacuum pumping device 112 with a liquid separation device 140 will always be activated first.

[0035] The invention may be summarized as follows. In the field of using a plurality of milking devices 101 in a milking system 100, a vacuum system 110 is used which comprises a pipe system 111 with a vacuum supply line 113 and a pump connecting line 114, wherein the milking devices 110 are connected to the vacuum supply line 113. Furthermore, the vacuum system 110 comprises at least three vacuum pumping devices 112 which are connected to the pump connecting line 114 and which each comprise a vacuum pump 130. At least two of the vacuum pumping devices 114 also comprise a liquid separation device 140 which is configured to extract liquid from the vacuum system 110, while at least one of the vacuum pumping devices 112 does not comprise such a liquid separation device 140. Controlling the vacuum system 110 comprises ensuring that the vacuum pump 130 is always in the active state in at least one of the vacuum pumping devices 112 with a liquid separation device 140 when the vacuum system 110 is in operation, so that active dehumidification of the vacuum system 110 always takes place despite the fact that not all vacuum pumping devices 112 comprise a liquid separation device 140.

Claims

CLAIMS1 . Milking system (100), comprising: a plurality of milking devices (101) for milking dairy animals; a vacuum system (110) for producing a underpressure in the milking devices (101); and a control unit (120) for controlling at least the vacuum system (110); wherein the vacuum system (110) comprises a pipe system (111) with a vacuum supply line (113) and a pump connecting line (114) which is in fluid communication with the vacuum supply line (113), wherein the milking devices (101) are connected to the vacuum supply line (113), and wherein the vacuum system (110) comprises at least three vacuum pumping devices (112) which are connected to the pump connecting line (114); wherein each of the vacuum pumping devices (112) comprises a vacuum pump (130) and the control unit (120) is configured to set an active state or an inactive state of the vacuum pump (130); wherein at least two of the vacuum pumping devices (112) furthermore comprise a liquid separation device (140) which is configured to extract liquid from the vacuum system (110), and which is situated at a position between the vacuum pump (130) and the pump connecting line (114), while at least one of the vacuum pumping devices (120) is without such a liquid separation device (140); and wherein the control unit (120) is configured such that when the vacuum system (110) is in operation, the vacuum pump (130) of at least one of the vacuum pumping devices (112) with a liquid separation device (140) is always in the active state.

2. Milking system (100) according to Claim 1 , wherein the vacuum pumping devices (112) with a liquid separation device (140) are connected to a portion of the pump connecting line (114) that is situated further from the vacuum supply line (113) than a portion of the pump connecting line (114) to which the at least one vacuum pumping device (112) without a liquid separation device (140) is connected.

3. Milking system (100) according to Claim 1 or 2, wherein the vacuum pumping devices (112) with a liquid separation device (140) are connected to a side of the pump connecting line (114) which is a bottom side of the pump connecting line (114) when the vacuum system (110) is in operation, and wherein the at least one vacuum pumping device (112) without a liquid separation device (140) is connected to a side of the pump connecting line (114) which is a top side of the pump connecting line (114) when the vacuum system (110) is in operation.

4. Milking system (100) according to any of Claims 1-3, wherein the vacuumpumping devices (112) with a liquid separation device (140) are connected to the pump connecting line (114) at a common position (117).

5. Milking system (100) according to any of Claims 1-4, wherein the liquid separation device (140) comprises a liquid store (141) with a discharge element (142) which is configured to close as a result of underpressure and to open as the pressure increases towards atmospheric pressure, so that discharge of stored liquid from the liquid store (141) via the discharge element (142) becomes possible.

6. Milking system (100) according to any of Claims 1-5, wherein each of the vacuum pumping devices (112) is connected to the pump connecting line (114) via a valve (116).

7. Milking system (100) according to any of Claims 1-6, wherein the vacuum system (110) comprises a sensor unit (121) which is operationally connected to the control unit (120) for detecting a momentary value of the underpressure in the pipe system (111).

8. Milking system (100) according to any of Claims 1-7, wherein the control unit (120) is configured so that a preset value (P) of the underpressure prevails in the pipe system (111) when the vacuum system (110) is in operation.

9. Milking system (100) according to Claim 8, wherein the control unit (120) is configured to minimize the number of vacuum pumps (130) in the active state.

10. Milking system (100) according to any of Claims 1-9, wherein the vacuum pumps (130) of the respective vacuum pumping devices (112) are configured to produce a vacuum on the basis of a movement, and wherein the control unit (120) is configured to vary a speed of the movement in a vacuum pump (130) in the active state.

11. Milking system (100) according to Claim 10, wherein the control unit (120) is configured such that, during use of the vacuum system (110) with at least two vacuum pumps (130) in the active state, the speed of the movement in at most one vacuum pump (130) in the active state is lower than a maximum speed, whereas the speed of the movement in the at least one other vacuum pump (130) in the active state is the maximum speed.

12. Method for controlling a vacuum system (110) to produce a underpressure in a plurality of milking devices (101) for milking dairy animals; wherein the vacuum system (110) comprises a pipe system (111) with a vacuum supply line (113) and a pump connecting line (114) which is in fluid communication with the vacuum supply line (113), wherein the milking devices (101) are connected to the vacuum supply line (113), and wherein the vacuum system (110) comprises at least three vacuumpumping devices (112) which are connected to the pump connecting line (114); wherein each of the vacuum pumping devices (112) comprises a vacuum pump (130) whose active state or inactive state is settable; and wherein at least two of the vacuum pumping devices (112) furthermore comprise a liquid separation device (140) which is configured to extract liquid from the vacuum system (110), and which is situated at a position between the vacuum pump (130) and the pump connecting line (114), whereas at least one of the vacuum pumping devices (120) is without such a liquid separation device (140); wherein the method comprises the following: ensuring that the vacuum pump (130) of at least one of the vacuum pumping devices (112) with a liquid separation device (140) is always in the active state when the vacuum system (110) is in operation, in particular by means of a control device which is configured for controlling the vacuum device.

13. Method according to Claim 12, wherein it is ensured that a preset value (P) of the underpressure prevails in the pipe system (111) when the vacuum system (110) in operation.

14. Method according to Claim 13, wherein the number of vacuum pumps (130) in the active state is minimized.

15. Method according to any of Claims 12-14, wherein the vacuum pumps (130) of the respective vacuum pumping devices (112) are configured to produce a vacuum on the basis of a movement, wherein, during use of the vacuum system (110) with at least two vacuum pumps (130) in the active state, a speed of the movement in a vacuum pump (130) in the active state is variable, and wherein it is ensured that the speed of the movement in at most one vacuum pump (130) in the active state is lower than a maximum speed, whereas the speed of the movement in the at least one other vacuum pump (130) in the active state is the maximum speed.