Milking system

Abstract

A milking system with a series of robotic milking devices (2-1, 2-2, 2-3, 2-4) has a cleaning system with a vessel (4) for cleaning liquid, a ring line (3) to and from said vessel, a pump (5) and a control unit (6). Each robotic milking device is fluidically connected to the ring line and can draw off cleaning liquid therefrom. Additionally, there is a parallel line (11) that branches off from the ring line between the pump and the series of robotic milking devices and feeds into the ring line again downstream of the series and upstream of the vessel, and also a flow restriction (15) in the ring line between the feed-in point (13) of the parallel line and the vessel, and a controllable valve (14) for opening and closing the parallel line. The control unit is configured to open said controllable valve if at least one of the robotic milking devices draws off cleaning liquid from the ring line. This allows cleaning liquid to be fed to the robotic milking device from two directions. The restriction in this case ensures sufficiently high flow resistance, and therefore pressure, in the ring line. Thus, even with (very) long ring lines, thorough cleaning can be ensured in a sufficiently reliable manner and without excessive energy consumption.

Description

[0001] Milking system

[0002] The present invention generally relates to a milking system having a plurality of robotic milking devices and a cleaning system. The cleaning system comprises a vessel for cleaning liquid, a ring line for conveying the cleaning liquid, which ring line runs from an outlet of said vessel back to an inlet of said vessel, a pump in the ring line, which pump is configured to pump the cleaning liquid through the ring line from said outlet to said inlet in a flow direction, and a control unit for controlling the cleaning system. Each robotic milking device is fluidically connected to the ring line at a respective connection and is configured to be cleanable by drawing off cleaning liquid from the ring line at said connection.

[0003] Such a system is known from NL2030165.

[0004] A disadvantage of the known system is the difficulty of ensuring a sufficient flow rate through each robotic milking device in the case of long lines and a correspondingly high line resistance. Although a heavier pump could of course be used, this not only leads to unnecessary energy consumption but also places unnecessary strain on robotic milking devices located close to the pump, because the pressure, and thus the flow rate, could then become too high there.

[0005] The invention aims to improve the known system in such a way that it still achieves a sufficient flow rate of the cleaning liquid even in the case of long lines without requiring additional pump capacity or the like.

[0006] The invention achieves this object by means of a milking system according to Claim 1 , in particular a milking system comprising a plurality of robotic milking devices and also a cleaning system for cleaning the robotic milking devices, wherein the cleaning system comprises a vessel for cleaning liquid, a ring line for conveying the cleaning liquid, which ring line runs from an outlet of said vessel back to an inlet of said vessel, a pump in the ring line, which pump is configured to, in an operating state, pump the cleaning liquid through the ring line from said outlet to said inlet in a flow direction, and a control unit for controlling the cleaning system, wherein each robotic milking device is fluidically connected to the ring line at a respective connection and is configured to be cleanable by drawing off cleaning liquid from the ring line at said connection, wherein the cleaning system further comprises a parallel line that branches off from the ring line at a first position on the ring line and feeds into the ring line at a second position, wherein the first position, viewed in the flow direction, is downstream of said pump and upstream of all said connections, and the second position, viewed in the flow direction, is downstream of all said connections, a flow restriction in the ring line, which flow restriction is configured to increase the pressure of the cleaning liquid in the ring line at said connections in the pump operating state, wherein the flow restriction, viewed in the flow direction, is downstream of said second position, and a controllable valve for opening and closing the parallel line, wherein the control unit is configured to open said controllable valve if at least one of the robotic milking devices draws off cleaning liquid from the ring line.

[0007] The invention makes use of the insight that when a robotic milking device draws off cleaning liquid from the ring line, two lines are actually guiding cleaning liquid to said robotic milking device. This results in a lower pressure drop and the pump can effectively achieve a higher flow rate given otherwise identical settings, or the same flow rate given a lower pump power or speed. If none of the robotic milking devices is drawing off cleaning liquid, said cleaning liquid can flow in a single direction at, for example, a lower flow rate. Such a situation may be useful in some cases, and will be explained further below.

[0008] It is noted here that said flow direction obviously applies while the valve is closed, since the direction in part of the ring line will be reversed while the valve is open and the robotic milking device is drawing off cleaning liquid. In addition, the robotic milking devices are cleaned by drawing off cleaning liquid and then passing this drawn-off cleaning liquid through the robotic milking device. The drawn-off cleaning liquid with the entrained contaminants is then drained, for example to a sewer system or to a collecting receptacle for use in a subsequent cleaning operation. It is therefore important to stress that, during cleaning, the drawn-off cleaning liquid is passed through the robotic milking device and is then drained, and is therefore not used in what is referred to as circulation cleaning of the robotic milking device.

[0009] As mentioned, the flow restriction, viewed in the flow direction, is downstream of said second position. This means that the flow restriction is upstream of or in said inlet of the vessel. It should also be noted that "fluidically connected" means that there is a connection through which (cleaning) liquid can flow, with said connection being closable with a valve or the like.

[0010] "If at least one of the robotic milking devices draws off cleaning liquid from the ring line" means that the controllable valve will be open when cleaning liquid is being drawn off, but also that it is reactively opened if it is detected that cleaning liquid is being drawn off. The former option is preferred. Moreover, the following discussion will only cover the situation where a single robotic milking device is cleaned by drawing off cleaning liquid, but the problem and the solution offered by the present invention also apply to the situation where a plurality of robotic milking installations are cleaned.

[0011] Particular forms of the invention are described in the dependent claims, and in the following part of the introduction of the description.

[0012] In embodiments, the pump is configured to, in the operating state, maintain a non-zero basic flow rate of the cleaning liquid through the ring line during at least a period with the controllable valve closed. An important aim of the ring line is to circulate the cleaning liquid in desired conditions in which it is not yet being drawn off. In particular, such circulation is desirable when the ring line and the cleaning liquid contained therein are being brought up to or maintained at temperature. Otherwise, prior to a hot-cleaning operation using hot cleaning liquid, the liquid could cool down to an excessive degree due to the long route through the still relatively cold ring line, and the cleaning of, for example, remote robotic milking devices would be less successful. By first allowing the cleaning liquid to flow through the ring line for a certain amount of time, preferably at a high flow rate, said ring line can be brought up to temperature for a better and more reliable cleaning result. Such circulation, for example also at a low flow rate, can also reduce the risk of frost damage. The otherwise stationary cleaning liquid could otherwise freeze relatively easily in the (long) ring line in the event of frost. Another important aim of the basic flow rate is to ensure that the pump can maintain the pressure in the ring line. This is because, to this end, the pump has to be running, but if the pump is always running in the same liquid, the latter will continue to heat up undesirably. A basic flow rate prevents this. Moreover, it is of course possible to configure the pump, or other components of the milking system, to bring the basic flow rate down to zero under other conditions, such as by switching off the pump or closing any valve in the ring line. This can be done for example during a frost-free time between hot-cleaning operations.

[0013] The length of the parallel line is not subject to any particular limitation. However, since it does not have any function of its own apart from enabling the dual supply, the length is in particular as short as possible. Thus, when the controllable valve is opened, hot cleaning liquid will cool down only slightly when flowing through the not yet pre-heated parallel line. For example, a length of the parallel line is at most 1 % of the length of the ring line. In particular, the length is at most 2 metres, more particularly at most 1 metre, rounded off, that is to say between 0.5 and 1 .5 metres. Moreover, an even shorter length is also possible, although this may make maintenance and the like more difficult given the presence of the controllable valve.

[0014] In embodiments, the flow restriction has a flow capacity that is adjustable by the control unit. As mentioned above, the flow restriction serves to provide a favourable pressure distribution in the ring line, in order to ensure that each robotic milking device can draw off cleaning liquid therefrom at a sufficient flow rate. However, under other conditions, it may be favourable to minimize the total flow resistance in the ring line, such as during cleaning of said ring line itself. Such cleaning may include, for example, purging the ring line and flushing said ring line with cleaning liquid. In such a case, the flow restriction impedes said purging, flushing or the like. It is then favourable if the flow restriction has an adjustable flow capacity.

[0015] In particular, the flow restriction comprises a restrictor valve. The restrictor valve can be opened and closed by the control unit in order to adjust the flow capacity. The flow capacity is of course highest when the restrictor valve is fully open, whereas a basic flow rate of the cleaning liquid can be provided if the restrictor valve is partially open. If the restrictor valve is closed, of course no flow back to the vessel is possible, and maximum flow to a robotic milking device that is drawing off cleaning liquid can be provided. Thus, the restrictor valve can advantageously be placed in three positions, namely "fully open", "closed" and an intermediate position "ajar". In particular, the restrictor valve is provided with a fixed flow opening. This means that even if the restrictor valve is closed per se, there is still a desired leakage, and thus a basic flow rate through the ring line. On the one hand this means that the fully closed position is thus no longer possible, but on the other hand the control of the valve is simpler and more reliable than in the case of a three-position valve. Other configurations, such as those having even more positions, are not excluded.

[0016] In embodiments, the milking system further comprises a bypass line over the flow restriction, there being provided in the bypass line a control valve that is controllable by the control unit. Thus, the functions of providing a basic flow rate, through the flow restriction with closed control valve, and providing a high flow rate, when the control valve is open, can be separated and optimized.

[0017] The bypass line can be provided over the flow restriction in a variety of ways, such as branching off from the ring line at a first bypass point upstream of the flow restriction in the flow direction and feeding into the ring line at a second bypass point downstream of the flow restriction in the flow direction. Advantageously, however, the bypass line runs from the parallel line to a part of the ring line between the flow restriction and said vessel. This has the following advantage. When the ring line is being purged or otherwise switched over to another fluid, the parallel line may form a dead-end section of line, of course when the controllable valve is closed. This is undesirable. By choosing to position the first bypass point specifically in the parallel line, the dead-end section of the parallel line is effectively smaller.

[0018] In embodiments, the control unit is configured to increase the flow capacity of the flow restriction, or to open the control valve, respectively. Thus, the control unit itself can automatically make the milking system suitable for example for pre-heating, by having the pump switched on and the flow restriction set to the basic flow rate, or cleaning of a robotic milking device, by opening the adjustable valve and the like. Of course, this could also be done manually. Moreover, it will be clear that in the case of purging with compressed air, a compressed-air inlet is provided on the milking system, such as on the ring line, and advantageously also a compressed-air source.

[0019] In particular, each robotic milking device comprises a robot control unit that is configured to provide the control unit with a command indicating that the robotic milking device in question is about to draw off cleaning liquid. The control unit can thus prepare, such as by pre-heating the ring line if a hot-cleaning operation is desired, or increasing the pump capacity to adjust it to the requested flow rate. Such settings are favourable if a robotic milking device needs to be cleaned outside of a normal cleaning schedule, such as after milking a sick dairy animal.

[0020] As an alternative or in addition, the milking system, or each robotic milking device, comprises a sensor that is configured to transmit to the control unit a sensor signal indicating that at least one robotic device, or respectively the robotic device in question, is drawing off cleaning liquid from the ring line. Based on this sensor signal, the control unit can then decide, for example, to run the pump faster and / or to open the adjustable valve, in order to increase the flow rate of the cleaning liquid. The sensor signal then serves as a detection or start signal for the cleaning. The sensor is, for example, a pressure sensor, flow-velocity sensor or flow-rate sensor. This is because opening a connection of a robotic milking device in order to begin drawing off cleaning liquid will relatively suddenly decrease the pressure in the ring line, or increase the flow velocity and / or flow rate through the ring line. From this, the control unit can determine that a robotic milking device requires cleaning, without the need for any separate communication with each robotic milking device. However, this will be less favourable for a hot-cleaning operation as this benefits from pre-heating the ring line prior to the actual cleaning. Moreover, a flow-rate or flow-velocity meter also has the advantage that the measured value can be used by the control unit to assess the cleaning quality by measuring whether the cleaning liquid has passed through the robotic milking device at a sufficiently high flow velocity and / or flow rate.

[0021] In embodiments, the control unit is configured to cause the robotic milking devices to draw off cleaning liquid in accordance with a programme. For example, the programme is configured to clean the robotic milking devices or in particular the whole milking system, or at least the milk-carrying parts thereof, three times a day at regular intervals. This meets certain legal requirements or standards. It is of course possible, or sometimes even necessary, to set a different programme, but all that is required in that case is to reprogramme the control unit.

[0022] The invention will be explained in more detail below on the basis of one or more exemplary embodiments and the drawing. In the drawing, the only figure schematically shows a milking system according to the invention.

[0023] The milking system is denoted in general by reference numeral 1 , and comprises a series of robotic milking devices 2-1 to 2-4, collectively also denoted solely by reference numeral "2" below, and also a cleaning system having a ring line 3, a vessel 4, a pump 5, a control unit 6 and a compressed-air source 7. For the sake of clarity, many components are not shown, such as specific milking means, robot arms, etc., which will of course be provided in practice. A person skilled in the art will be able to supplement this without any problems. However, this application will focus on components intended for cleaning the milking system 1 .

[0024] For cleaning of the milking system 1 , or at least for example robotic milking device 2-1 , cleaning liquid from the vessel 4 is pumped via the ring line 3 by the pump through the robotic milking device in question via the connection 10-1. For this purpose, a valve (not shown here) will open the supply to the robotic milking device 2-1 , controlled by either the control unit 6 or the robot control unit 9-1 . Downstream of the robotic milking device 2-1 , the drawn-off cleaning liquid containing contaminants flows through the discharge 8-1 to, for example, a sewer system or collection basin. It should be noted that the control unit 6 is shown as being connected to only the pump 5, but the control unit will be operatively connected to all relevant components, such as said components with different positions or settings. After cleaning of the robotic milking device 2-1 , the supply valve (not shown) will be closed again and, for example, another robotic milking device can be cleaned.

[0025] Said cleaning operations on the robotic milking devices 2 can be carried out according to a fixed programme, such as three times a day after in each case approximately 8 hours. It may also be necessary to clean a robotic milking device 2 in the intervening period, such as after milking a sick dairy animal. In this case, for example, the robotic milking device 2-1 itself will be able to send a signal to start cleaning to the control unit 6 via its robot control unit 9-1 , or such an instruction is sent centrally from the control unit 6.

[0026] For purging the ring line 3 after cleaning, a compressed-air source 7 is provided, which sends compressed air through the ring line via an actuable valve 20 and in so doing pushes the cleaning liquid still present in the ring line 3 back to the vessel 4 or, if required, to a sewer system or other discharge.

[0027] The above description largely corresponds to what is known from the prior art. However, if the ring line 3 is made longer, the flow resistance will also increase under otherwise unchanged conditions. This results in undesirable effects on cleaning. In particular, the flow rate or flow velocity of the cleaning liquid may become undesirably low. This could be combated by increasing the pump capacity and / or decreasing the flow resistance by increasing the cross-sectional area of the ring line, etc. However, this can lead to undesirable side effects, such as higher energy consumption, excessive pressure in the ring line at the start of the ring line or at the first robotic milking device(s), or an unnecessarily large volume of cleaning liquid in the ring line.

[0028] According to the present invention, the problem is combated with the aid of a parallel line 1 1 that branches off from the ring line 3 at first position 12 and feeds into the ring line 3 at second position 13 and is closable with a controllable valve 14. When no cleaning is desired, the valve 14 is closed. When cleaning is desired, or at least if cleaning liquid has to be drawn off from the ring line by one or even more robotic milking devices 2, the controllable valve 14 is opened by the control unit 6. The pump 5, which can be switched to an active state with a higher capacity by the control unit 6, can then pump cleaning liquid through the ring line 3 in the direction of the arrows to the robotic milking device 2 that is drawing off cleaning liquid, both (in the drawing) in a clockwise direction from position 12 and, via the parallel line 11 and then another part of the ring line 3, in an anticlockwise direction. This effectively doubles the cross section of the ring line. As a result, the flow rate and therefore the flow velocity of the cleaning liquid through the robotic milking device 2 can be increased given identical pump settings. Alternatively, the energy consumption of the pump can be greatly reduced if a higher flow rate through the robotic milking device is not necessary, since the flow rate to be generated by the pump in each of the two parts of the ring line downstream of position 12 is only half as high as when the cleaning liquid is pumped through the ring line from one side only. Since the long ring line provides the majority of the flow resistance but now has a lower resistance at the requested flow rate, the requested pump power at a desired flow rate is slightly lower. Of course, it is also possible for the effects of energy saving and higher flow rate to both be partially achieved in any desired proportion. A flow restriction is provided in the ring line in order to prevent cleaning liquid from flowing ineffectively back to the vessel 4 from the second connection 12, or alternatively to keep the pressure in the ring line sufficiently high, thus ensuring that the flow rate at which cleaning liquid can be drawn off from the ring line 3 is sufficiently high. A flow restriction is in this respect any component that has or can generate such a high flow resistance that the flow resistance of the rest of the flow path, particularly the ring line 3, is, if not relatively negligible, then at least smaller than that of the remaining part of the flow path.

[0029] In the figure, a first example of a flow restriction is denoted in general by reference numeral 15, effectively as a narrowing in the ring line. For example, the flow restriction 15 comprises a type of plug or the like containing a passage 16 that allows a basic flow rate through the ring line. The basic flow rate is a flow rate that is much lower than the flow rate desired for cleaning, for example 10% thereof, or even less. The basic flow rate serves, for example, to maintain the ring line at temperature and to ensure that the pump, which serves to maintain the pressure in the ring line, is not always pumping in the same water. To this end, hot cleaning liquid is pumped through the ring line 3 from the vessel 4 at a low flow rate. Since no robotic milking device 2 is requesting cleaning at that point in time, the controllable valve 14 is closed.

[0030] It may also be favourable to maintain a basic flow rate if there is a risk of frost damage, i.e. at low temperatures. At such a flow rate, the cleaning liquid, which is kept for example at a certain desired temperature above freezing (zero degrees Celsius for water, lower for solutions), can protect the milking system 1 , or at least the ring line and coupled components, from freezing.

[0031] In some situations, it is undesirable for there to be a restriction in the circuit, in particular the ring line. For example, it is sometimes desirable to clean the ring line specifically. To this end, cleaning liquid needs to be pumped through the ring line 3. If said cleaning liquid can then only be circulated at a high flow rate by draining it via a robotic milking device 2, or via a discharge to a sewer system, that is an unnecessary constraint. For example, circulation cleaning of the ring line is desired. It is also possible to pre-heat the ring line 3 before starting a hot-cleaning operation on one or more robotic milking devices. This should preferably be done at a high flow rate. The circulated hot cleaning liquid heats up the ring line and, after a certain amount of time, or sufficient preheating, cleaning of the robotic milking devices 2 can begin. It is also sometimes desirable to remove cleaning liquid from the ring line, particularly by purging using compressed air from the compressed-air source 7. This is not effective if the flow restriction provides a high flow resistance. In order to allow (circulation) cleaning, pre-heating and / or purging of the ring line, or any other desired actions, a bypass line 17 is provided, containing a control valve 18 controllable by the control unit 6. If a high flow rate through the ring line 3 is desired, the control unit opens the control valve 18 so that cleaning liquid and / or compressed air no longer encounters resistance from the flow restriction. After cleaning, the control valve 18 can of course be closed again. The figure shows the bypass line as running from the parallel line to the ring line 3 between the restriction 15 and the vessel 4. It is also possible to provide the bypass line 17 elsewhere around the restriction 15, such as from a point on the ring line 3 between the second position 13 and the restriction 15 to a point on the ring line between the restriction 15 and the vessel 4. It should be noted here that the part of the overall line system that is difficult or impossible to purge or pre-heat, namely the dead-end part of the parallel line 11 when valve 14 is closed, is effectively longer in the latter case than in the former case. This can be resolved by, for example, also briefly opening the valve 14 after purging the ring line 3, although this requires an additional action.

[0032] The figure also shows a second example of a flow restriction, in the form of adjustable restriction 19. This is an alternative, and not an addition, to the restriction 15. The restriction 19 can, for example, be embodied as a valve having an adjustable flow. For example, it may have a low flow for the basic flow rate, and a higher flow if a higher flow rate is desired. An advantage of this embodiment is that the cleanability of the ring line directly around the restriction can be improved, because, in the case of restriction 15, the flow rate through said restriction is always low. However, setting a variable valve to a low flow is more complex than the combination of a fixed low flow with open / closed control of a parallel valve.

[0033] The exemplary embodiments and details shown serve merely to explain the invention and are not intended to be limiting. The scope of protection is determined by the attached claims.

Claims

CLAIMS1 . Milking system comprising a plurality of robotic milking devices and also a cleaning system for cleaning the robotic milking devices, wherein the cleaning system comprises:- a vessel for cleaning liquid,- a ring line for conveying the cleaning liquid, which ring line runs from an outlet of said vessel back to an inlet of said vessel,- a pump in the ring line, which pump is configured to, in an operating state, pump the cleaning liquid through the ring line from said outlet to said inlet in a flow direction, and- a control unit for controlling the cleaning system, wherein each robotic milking device is fluidically connected to the ring line at a respective connection and is configured to be cleanable by drawing off cleaning liquid from the ring line at said connection, characterized in that the cleaning system further comprises- a parallel line that branches off from the ring line at a first position on the ring line and feeds into the ring line at a second position, wherein the first position, viewed in the flow direction, is downstream of said pump and upstream of all said connections, and the second position, viewed in the flow direction, is downstream of all said connections,- a flow restriction in the ring line, which flow restriction is configured to increase the pressure of the cleaning liquid in the ring line at said connections in the pump operating state, wherein the flow restriction, viewed in the flow direction, is downstream of said second position, and- a controllable valve for opening and closing the parallel line, wherein the control unit is configured to open said controllable valve if at least one of the robotic milking devices draws off cleaning liquid from the ring line.

2. Milking system according to Claim 1 , wherein the pump is configured to, in the operating state, maintain a non-zero basic flow rate of the cleaning liquid through the ring line during at least a period with the controllable valve closed.

3. Milking system according to either of the preceding claims, wherein a length of the parallel line is at most 1 % of a length of the ring line, in particular at most 2 metres, more particularly at most 1 metre, rounded off.

4. Milking system according to one of the preceding claims, wherein the flow restriction has a flow capacity that is adjustable by the control unit.

5. Milking system according to Claim 4, wherein the flow restriction comprisesa restrictor valve, in particular wherein the restrictor valve is provided with a fixed flow opening.

6. Milking system according to one of the preceding claims, further comprising a bypass line over the flow restriction, there being provided in the bypass line a control valve that is controllable by the control unit.

7. Milking system according to Claim 6, wherein the bypass line runs from the parallel line to a part of the ring line between the flow restriction and said vessel.

8. Milking system according to one of the preceding claims, wherein the control unit is configured to increase the flow capacity of the flow restriction, or to open the control valve, respectively.

9. Milking system according to one of the preceding claims, wherein each robotic milking device comprises a robot control unit that is configured to provide the control unit with a command indicating that the robotic milking device in question is about to draw off cleaning liquid, and / or wherein each robotic milking device comprises a sensor that is configured to transmit to the control unit a sensor signal indicating that the robotic device in question is drawing off cleaning liquid from the ring line.

10. Milking system according to one of the preceding claims, wherein the control unit is configured to cause the robotic milking devices to draw off cleaning liquid in accordance with a programme.

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