Milking system with a milk-transporting line and a filter device for filtering milk in the milk-transporting line

Abstract

In the field of transporting and filtering of milk, a milk-transporting line (111) for transporting milk and a filter device (150) for filtering the milk in the milk-transporting line are used in a milking system (100). The filter device comprises an assembly of at least two filter units (151a, 151b, 151c, 151d) through which milk can flow simultaneously, wherein each of the filter units has a functional filter surface. In a cleaning process, cleaning fluid is passed through a limited part of a sum of the respective functional filter surfaces of the filter units, so that locally intensified cleaning operation may be realised, that is to say, cleaning takes place with greater force than would be the case if a cleaning fluid were to be passed through the total sum of the respective functional filter surfaces of the filter units.

Description

[0001] Milking system with a milk-transporting line and a filter device for filtering milk in the milktransporting line

[0002] The invention relates to a milking system, comprising a milk-transporting line for transporting milk; a filter device for filtering the milk in the milk-transporting line; and an operating system for operating the filter device, which is configured to cause cleaning fluid to be passed through the filter device.

[0003] Filtering milk in a milk-transporting line of a milking system is generally known. WO-2022 / 049516-A1 discloses a milking device for milking dairy animals which comprises an automatically cleanable milk filter for filtering milk which is obtained in the milking device.

[0004] The milking of dairy animals makes it necessary for the milking device to be cleaned regularly in its entirety in order to prevent deposits of milk residues from forming and bacteria and the like from growing in the milk residues. To this end, it is known to clean milking devices, wherein initially as much milk as possible is removed from the milking device. Subsequently, the milk residues, including inter alia milk fats and milk proteins, are removed by means of hot water containing an acid or a base. Finally, rinsing with cold or lukewarm water is performed in order to remove residues of the acidic or basic cleaning liquid and to cool down the milking device for subsequent use with dairy animals. Optionally, a rinsing with cold or lukewarm water is performed before the hot water is supplied.

[0005] With the milking device, it is also necessary to filter the milk obtained before it goes to the milk tank where the milk is collected. During this process, dirt such as manure particles and bedding particles, hairs, but also cell clusters and flakes and the like are removed from the milk. After some time, the milk filter which is used in this process will have become soiled to such a degree that it is no longer suitable for further use. In view thereof, it is important to ensure that an action is performed which provides a clean milk filter for new milking operations.

[0006] WO-2022 / 049516-A1 provides information about a method in which the milk filter is cleaned during every main cleaning operation of the entire milking device. Furthermore, it is possible for a pressure drop meter or the like to be provided which measures the pressure drop across the milk filter, and which emits a signal to a control unit of the milking device if the pressure drop exceeds a threshold value, in order to subject the milk filter to an intermediate cleaning operation. The cleaning operation may be performed, for example, by passing cleaning liquid through the milk filter in the same direction as the milk, that is to say from the spot where the dairy animals are being milked through the milk filter to the milk tank via a milk-transporting line. The hot, acidic or basic liquids to be used can efficiently dissolve, for example, fat residues, protein residues or calcium residues. The fact that hairs, sand and the like are pushed further against the milk filter without being removed or dissolved is less advantageous. However, to this end, a backwash cleaning operation may be performed, during which cleaning liquid is supplied in the opposite direction.

[0007] Another known type of milk filter is a so-called double filter which comprises two filter components. In use, only one filter component of such a double filter is used. With the double filter, a valve system is used by means of which a milk flow is allowed to pass through to the one filter component and is blocked off to the other filter component. The filter components are disposable items. Once the one filter component has reached a maximum degree of contamination, the valve system is actuated to stop the milk supply to this filter component and to switch to the other filter component. The contaminated filter component may be replaced by a new filter component. In this way, a milking system which uses the double filter does not have to be stopped when a filter component has to be replaced. Even with a double filter, it is desirable to have the possibility of performing a cleaning operation with a cleaning fluid, in particular a cleaning operation of a newly installed filter component before it will be used, in order to wash away any possible contaminants which might be present in the filter component and to prevent contamination of milk with such contaminants.

[0008] WO-2023 / 111942-A1 discloses a milking system which comprises two or more milking devices for milking dairy animals. This milking system has a central utility system which is connected to every milking device in the milking system and which comprises a cleaning unit which serves for cleaning the milking devices and milk-carrying parts of the central utility system, wherein the cleaning unit comprises at least one fluidtransporting line for transporting cleaning fluid, and wherein each of the milking devices is in fluid communication with the fluid-transporting line. The milking system furthermore comprises a milk-transporting line which connects a buffer unit for receiving milk from the milking devices and temporarily storing the milk with a bulk milk storage device, such as one or more bulk milk tanks or a tank in a lorry. This milk-transporting line may contain a filter device for filtering the milk. WO-2023 / 111942-A1 describes an embodiment of a milking system which comprises four milking devices. This means that the filter device has to process contaminants from four milking devices and will therefore be contaminated to the maximum degree sooner compared to a situation with fewer milking devices, so that cleaning the filter device or replacing a filter component has to be carried out more often. With a view thereto, it is desirable to offer a possibility to extend the usage time of a filter device for filtering milk in a milk-transporting line, i.e. the time for which the filter device is able to function without requiring cleaning of the filter device or replacement of a filter component. Furthermore, with regards to the cleaning operation of the filter device, it is desirable to offer the possibility of carrying this out in an efficient manner.

[0009] In the context of a milking system with a milk-transporting line for transporting milk, the invention provides the following for the milking system: a filter device for filtering the milk in the milk-transporting line, which filter device comprises an assembly of at least two filter units through which milk is able to flow simultaneously during the milking operation, wherein each of the filter units has a functional filter surface and the assembly has a sum of the respective functional filter surfaces of the filter units; and an operating system for operating the filter device which is configured to cause cleaning fluid to be passed through a limited part of said sum of the respective functional filter surfaces of the filter units during cleaning.

[0010] Firstly, it should be noted that the invention provides a new arrangement of a filter device. In particular, the invention provides a filter device which comprises an assembly of at least two filter units through which milk can flow simultaneously during the milking operation, wherein each of the filter units has a functional filter surface. Such a filter device comprises, for example, a number of parallel automatically cleanable milk filters, or a number of parallel double filters, wherein a central supply of milk to the filter device branches out, so that the milk is passed through at least two filter units in at least two separate flows. After having passed through the filter units, the separate flows may be combined again to form a single flow. In this way, the invention provides sufficient functional filter surface for every situation in a practical way, for example a situation as is known from WO-2023 / 111942-A1 , in which milk from two or more milking devices is collected at a central position and is filtered during transportation from this central position, with the term “sufficient” intended to mean that the filter device has an acceptable usage time.

[0011] Secondly, it should be noted that the invention offers a possibility of bringing about effective cleaning of said filter device with the assembly of at least two filter units through which milk can flow simultaneously during the milking operation. To this end, the invention provides a new way of cleaning, namely a way of cleaning which comprises passing cleaning fluid through a limited part of a sum of the respective functional filter surfaces of the filter units. This aspect of the invention is based on an insight of the invention that, in a situation involving a plurality of filter units through which milk can flow simultaneously, it is possible not to use, as desired, a part of the sum of the respective functional filter surfaces of the filter units for through-flow, as a result of which the part that is used can be cleaned using more force, without requiring an increased pressure which the through-flow brings about.

[0012] EP0653153A1 discloses a milk filter device with two filters, in which the one filter filters milk while the other is cleaned in counterflow, and vice versa. The changeover can be effected in an automated manner. No simultaneous through-flow by milk or cleaning fluid of various sums of filter surfaces is involved.

[0013] US5769025 discloses yet another milk filter device wherein milk can flow through one or two milk filters in parallel, but wherein the filters are only replaced instead of being cleaned. No mention is made about cleaning with a cleaning fluid at all.

[0014] In order to use, according to the present invention, a limited part of a sum of the respective functional filter surfaces of the filter units for the purpose of cleaning, the invention offers at least two practical possibilities, namely passing cleaning fluid through the functional filter surface of fewer filter units than the total number thereof, and / or passing cleaning fluid through a limited part of the functional filter surface of each of the filter units. In the context of the milking system, the operating system is configured to effect one these two possibilities. In the context of the invention, the operating system may be designed in any suitable way. In many practical cases, the operating system may comprise both one or more physical components as a control unit for actuating the physical components. Said physical components may be configured, in particular, to assume various positions in order thus to determine to which degree the functional filter surface of each of the filter units will be used, for example by freely passing a fluid flow to a filter unit or at least partly blocking it, or by covering an adjustable portion of the functional filter surface of a filter unit, thus causing an adjustable portion of the functional filter surface to remain unused. The latter may be achieved, for example, if a filter unit is provided with a slide which can be pulled over the functional filter surface to a lesser or greater degree. The degree to which a filter unit contributes to the filter function of the filter device may differ for each filter unit.

[0015] In a practical embodiment, the operating system comprises a valve system for regulating flows of fluid through the filter device. According to the invention, it is possible for at least one setting of the valve system to be brought about in which a flow of cleaning fluid through only a limited number of the filter units is possible. The operating system furthermore comprises a control unit which is generally configured to actuate the valve system, and which is at least capable of bringing about said at least one setting of the valve system.

[0016] It is possible for the control unit to be configured to bring about a succession of at least two different settings of the valve system, in which a flow of cleaning fluid through in each case one or more other filter units is possible. This results in the very powerful cleaning operation being performed in various filter units over time. The succession of at least two different settings may be selected such that all filter units are subjected to the very powerful cleaning operation at least once.

[0017] The concept of using a limited part of a sum of the respective functional filter surfaces of the filter units for the purpose of cleaning does not exclude the use of the total sum of the respective functional filter surfaces of the filter units at another point in time during a cleaning process. The operating system may therefore also be configured to bring about that cleaning fluid is passed through the total sum of the respective functional filter surfaces of the filter units.

[0018] In the context of the invention, a suitable direction for the cleaning fluid may be chosen by the filter device. The operating system may, for example, also be configured to bring about a counterflow cleaning operation, wherein cleaning fluid is passed through the filter device in a direction which is opposite to the direction of a milk flow through the filter device.

[0019] The invention covers any suitable embodiment of the filter device. It is, for example, possible for at least one of the filter units to comprise a double filter with two filter components, wherein the valve system is configured simultaneously to allow a flow of fluid to pass to the one filter component and to block a flow of fluid to the other filter component. It is furthermore possible for at least one of the filter units to comprise a fixed and durable filter component which is configured in such a way that the soiling caused by milk is removed from time to time, but it is also possible for at least one of the filter units to comprise a disposable filter component.

[0020] In particular with embodiments of the filter unit with a fixed and durable filter component, a significant advantage of the aforementioned counterflow cleaning operation emerges. Such a fixed and durable filter component is, for example, a metal pipe with holes, as is described in WO-22049515-A1 and WO-22049516-A1. Filter components which are designed in this way, but also other metal filter components, such as simple discs with holes arranged transversely in the milking line, etc., are readily automatically cleanable, so that they can function for a long time without having to be replaced. The advantage of the counterflow cleaning operation according to the invention is in this case that the cleaning operation can be intensified by means of the stronger through-flow, if the filter surface through which the cleaning fluid flows is reduced compared to the filter surface through which the milk flows during filtering. The force with which the cleaning fluid tries to loosen the filtered particles is thus in principle already greater than the force with which these particles were pressed onto the filter component during filtering, so that it is highly likely that these can be removed. Consequently, the time during which the filter device is able to function without human intervention can thus be significantly extended. In case the filter component comprises a so-called milk filter sock or another component with a woven or similar structure, counterflow cleaning cannot be used, because the filtered particles are subject to filtering action in both possible directions of through-flow due to the specific structure.

[0021] A practical example of a milking system in which the invention may be used, is a milking system as known from WO-2023 / 111942-A1 , that is to say, a milking system comprising at least two milking devices for milking dairy animals, each provided with a milking line, wherein the respective milking line of at least two of the milking devices is attached to the milk-transporting line, directly or via one or more other components of the milking system.

[0022] The invention will be explained below with reference to the figures which are generally diagrammatic and relate to non-limiting exemplary embodiments of a milking system and components thereof, with identical reference numerals denoting identical or similar components, and in which:

[0023] Figure 1 shows a diagrammatic representation of the milking system,

[0024] Figure 2 shows a diagrammatic representation of a first embodiment of a filter device of the milking system, wherein flows of milk are indicated,

[0025] Figure 3 shows the same diagrammatic representation of the first embodiment of the filter device of the milking system, wherein flows of fluid are indicated for a simultaneous cleaning operation of four filter components of the filter device,

[0026] Figure 4 shows the same diagrammatic representation of the first embodiment of the filter device of the milking system, wherein flows of fluid are indicated for a cleaning operation of a first filter component of the filter device,

[0027] Figure 5 shows the same diagrammatic representation of the first embodiment of the filter device of the milking system, wherein flows of fluid are indicated for a cleaning operation of a second filter component of the filter device,

[0028] Figure 6 shows the same diagrammatic representation of the first embodiment of the filter device of the milking system, wherein flows of fluid are indicated for a cleaning operation of a third filter component of the filter device,

[0029] Figure 7 shows the same diagrammatic representation of the first embodiment of the filter device of the milking system, wherein flows of fluid are indicated for a cleaning operation of a fourth filter component of the filter device,

[0030] Figure 8 shows a diagrammatic representation of a second embodiment of a filter device of the milking system, wherein flows of milk are indicated,

[0031] Figure 9 shows the same diagrammatic representation of the second embodiment of the filter device of the milking system, wherein flows of fluid are indicated for a simultaneous cleaning operation of four filter components of the filter device,

[0032] Figure 10 shows the same diagrammatic representation of the second embodiment of the filter device of the milking system, wherein flows of fluid are indicated for a cleaning operation of a first filter component of the filter device,

[0033] Figure 11 shows the same diagrammatic representation of the second embodiment of the filter device of the milking system, wherein flows of fluid are indicated for a cleaning operation of a second filter component of the filter device,

[0034] Figure 12 shows the same diagrammatic representation of the second embodiment of the filter device of the milking system, wherein flows of fluid are indicated for a cleaning operation of a third filter component of the filter device, and

[0035] Figure 13 shows the same diagrammatic representation of the second embodiment of the filter device of the milking system, wherein flows of fluid are indicated for a cleaning operation of a fourth filter component of the filter device.

[0036] Figure 1 is a diagrammatic representation of a milking system 100 which comprises a group 101 of four milking devices 102. The milking devices 102 serve for milking dairy animals, such as cows, and may be automatic milking robots where the dairy animals can independently enter and exit. In addition to the milking devices 102, the milking system 100 comprises a central utility system 110 and a milk-transporting line 111 for transporting milk to a bulk milk-storage system, such as a bulk milk tank 103. The milking devices 102 use a vacuum in order to function. In the milking system 100, the vacuum is provided centrally by a central vacuum system 120 which is attached to the milking devices 102 via a vacuum line.

[0037] The central utility system 110 comprises a control unit 130 and a buffer unit 140 for temporarily storing milk which originates from the milking devices 102, wherein each of the milking devices 102 is connected to the buffer unit 140 by a milking line 104. In particular, the respective milking lines 104 of the milking devices 102 are attached to an inlet of a valve system 145, and the buffer unit 140 comprises a first buffer tank 141 and a first buffer line 143 which runs from a first outlet of the valve system 145 to the first buffer tank 141 , and also a second buffer tank 142 and a second buffer line 144 which runs from a second outlet of the valve system 145 to the second buffer tank 142. Depending on the setting of the valve system 145, the milk which is obtained in the milking devices 102 is passed to the first buffer tank 141 or the second buffer tank 142 for temporary storage. The milk is transported from the respective buffer tank 141 , 142 to the bulk milk tank 103 in a constant or continuous flow via the milk-transporting line 111. The milk-transporting line 111 comprises a milk pomp 112, a filter device 150 and a cooling device 160 which may be, for example, a heat exchanger. When milk flows to the bulk milk tank 103 through the milk-transporting line 111 , it is filtered at the location of filter device 150 and cooled at the location of the cooling device 160.

[0038] In order to clean the milk-carrying parts of the milking system 100, such as the milking devices 102, the milking lines 104, the buffer unit 140 and the milk-transporting line 111 comprising the milk pump 112, the filter device 150 and the cooling device 160, the central utility system 110 comprises a cleaning unit 170. The cleaning unit 170 comprises a first cleaning fluid container 171 and a first cleaning fluid-transporting line 173 via which a fluid outlet of the first cleaning fluid container 171 is connected to a fluid inlet of each of the milking devices 102 and via which a fluid inlet of the first cleaning fluid container 171 is connected to a fluid outlet of each of the milking devices 102. The cleaning unit 170 furthermore comprises a second cleaning fluid container 172 and a second cleaning fluid-transporting line 174 via which a fluid outlet of the second cleaning fluid container 172 is connected to the fluid inlet of each of the milking devices 102 and via which a fluid inlet of the second cleaning fluid container 172 is connected to the fluid outlet of each of the milking devices 102. In this way, it is possible for the cleaning unit 170 to supply cleaning fluid to each of the milking devices 102 separately and discharge it from each of the milking devices 102 separately.

[0039] The control unit 130 is configured to initiate, either from time to time or by providing an indication to an operator, a process in which cleaning fluid from one of the buffer tanks 141 , 142 is passed through the milk-transporting line 111. In this way, milk residues are removed from the milk-transporting line 111 and the growth of bacteria in the milk-transporting line 111 is counteracted. Filling of one of the buffer tanks 141 , 142 with cleaning fluid is possible because each of the first buffer line 143 and the second buffer line 144 can be brought into communication with the outlets of the cleaning fluid containers 171 , 172 via valves 175, 176. If cleaning fluid is passed through the milk-transporting line 111 , cleaning of, inter alia, the filter device 150 takes place. Below, an explanation will be given with reference to Figures 2-13 of the construction of the filter device 150 and aspects of a cleaning process of the filter device 150 will be named.

[0040] The filter device 150 comprises an assembly of a number of filter units 151 . The number is at least two and, in the case of the examples which are shown in Figures 2-13, the number is four. Figures 2-7 relate to a first embodiment of the filter device 150 in which each of the filter units 151 comprises an automatically cleanable milk filter with a single, durable filter component 152. Figures 8-13 relate to a second embodiment of the filter device 150 in which each of the filter units 151 comprises a double filter with two filter components 153, 154. The filter components 153, 154 of the double filter are disposable items and the filter components 153, 154 are therefore arranged so as to be removable, whereas in the case of the automatically cleanable milk filter the filter component 152 may be arranged in a fixed manner.

[0041] Figure 2 diagrammatically shows how milk flows through the filter device 150 with the automatically cleanable milk filters during normal operation of the milking system 100. On the right-hand side of the figure, an inward-bound flow of milk M0 is indicated by means of an arrow. In the filter device 150, the various filter units 151 are arranged in parallel, so that the milk can simultaneously flow through the filter units 151. The inward-bound flow of milk is split into four flows of milk M1 , M2, M3, M4, so that some of the inward-bound milk flows through each of the filter units 151 . The direction in which the milk passes through the respective filter components 152 is indicated by means of an arrow in Figure 2. The four flows of milk M1 , M2, M3, M4 are reunited downstream of the filter units 151 , and are thus combined to form a single outward-bound milk flow M5, as is indicated on the left-hand side of Figure 2 by means of an arrow.

[0042] Figure 2 furthermore shows that a valve system 155 for regulating flows of fluid through the filter device 150 is provided. In particular, the valve system 155 comprises valves 156, 157 on both sides of each of the filter components 152. The control unit 130 is configured to actuate the valve system 155. During normal operation of the milking system 100, when milk flows through the filter device 150, the setting of the valve system 155 is normally a setting in which all valves 156, 157 are in an open position, that is to say, a position to allow a flow of fluid to pass. The illustrated valve system 155 provides maximum flexibility with regard to possibilities to open or close the filter components 152 for a flow of fluid from an arbitrary direction, optionally separately, i.e. per filter component 152. If desired, a simplified valve system 155 with only one valve may be used on a single side of each of the filter components 152.

[0043] Figure 3 relates to a cleaning process and diagrammatically shows how cleaning fluid flows through the filter device 150 with the automatically cleanable milk filters during the cleaning process. The setting of the valve system 155 is the same as during normal operation of the milking system 100. On the left-hand side of the figure, an inward-bound cleaning fluid flow F0 is indicated by means of an arrow. The inward-bound cleaning fluid flow is split into four cleaning fluid flows F1 , F2, F3, F4, so that some of the inward-bound cleaning fluid flows through each of the filter units 151. The direction in which the cleaning fluid moves through the respective filter components 152 is indicated by an arrow in Figure 3. The four cleaning fluid flows F1 , F2, F3, F4 are reunited downstream of the filter units 151 , and are thus combined to form a single outward-bound cleaning fluid flow F5, as indicated on the right-hand side of Figure 3 by means of an arrow. The flow direction during the cleaning process is opposite to the flow direction during the milking process, so that contaminants can readily be removed from the automatically cleanable milk filters, from the side of the automatically cleanable milk filters from which they ended up in the automatically cleanable milk filters to begin with.

[0044] The cleaning process may comprise, for example, pre-rinsing or rinsing with water, during which the water is passed simultaneously through the filter units 151 of the filter device 150. However, this is not obligatory. The through-flow of the filter device 150 with cleaning fluid illustrated in Figure 3 is therefore optional and not essential in the context of the invention. According to the invention, a cleaning process at least comprises passing cleaning fluid through a limited part of a sum of the respective functional filter surfaces of the filter units. Figures 4-7 illustrate a possible way of achieving this in the filter device 150 with the automatically cleanable milk filters. Below, the filter units 151 as illustrated in the figures from top to bottom will be indicated as first filter unit 151a, second filter unit 151b, third filter unit 151c and fourth filter unit 151 d.

[0045] Figure 4 shows a setting of the valve system 155 in which the inward-bound cleaning fluid flow F0 is only passed through a single filter unit 151 , namely the first filter unit 151a. In the other filter units 151 b, 151c, 151d, no flow of cleaning fluid is possible due to the closed position of a number of the valves 156, 157 of the valve system 155. In a similar way, Figure 5 illustrates a situation in which cleaning fluid flows through the second filter unit 151b while it cannot flow through the other filter units 151a, 151c, 151 d, Figure 6 illustrates a situation in which cleaning fluid flows through the third filter unit 151c while it cannot flow through the other filter units 151a, 151 b, 151 d, and Figure 7 illustrates a situation in which cleaning fluid flows through the fourth filter unit 151d while it cannot flow through the other filter units 151a, 151 b, 151c. If desired, the situations from Figures 4-7 may be brought about in succession during the cleaning process, wherein the valve system 155 is always adjusted in a suitable manner by the control unit 130. In any case, by bringing about the situations in which not all filter units 151a, 151 b, 151c, 151 d are opened simultaneously, a cleaning of separate filter units 151a, 151 b, 151c, 151d is achieved which is significantly more powerful than if cleaning fluid were to be passed through all filter units 151a, 151b, 151c, 151 d simultaneously.

[0046] For the sake of completeness, it should be noted that variations on the described cleaning process are possible. Thus, in the illustrated example with the four filter units 151a, 151b, 151c, 151 d, cleaning fluid may be passed through a limited number of two or three of these filter units 151a, 151b, 151c, 151 d simultaneously.

[0047] Figure 8 diagrammatically indicates how milk flows through the filter device 150 with the double filters during normal operation of the milking system 100. Compared to the filter device 150 with the automatically cleanable milk filters, the valve system 155 is of a different kind. The valves 156, 157 are arranged on either side of the pair of filter components 153, 154 of each double filter, and are designed in such a way that one position is simultaneously an open position for the one filter component 153, 154 and a closed position for the other filter component 153, 154, and that another position is simultaneously a closed position for the one filter component 153, 154 and an open position for the other filter component 153, 154. Thus, a situation in which both filter components 153, 154 can be flowed through is prevented. If a position of the valves 156, 157 on either side of the filter components 153, 154 is the same, then one of the filter components 153, 154 can be flowed through, and if a position of the valves 156, 157 on either side of the filter components 153, 154 is different, then none of the two filter components 153, 154 can be flowed through.

[0048] In a way similar to the illustrated filter device 150 with the automatically cleanable milk filters, the illustrated filter device 150 with the double filters comprises four filter units 151a, 151b, 151c, 151d which can be flowed through simultaneously depending on the setting of the valve system 155 or, as desired, can only be used to a limited degree. Figure 8 shows, by way of example, that in each of the double filters milk flows through a first filter component 153 of the two filter components 153, 154 during a milking process. Figure 9 illustrates a cleaning process which could take place after the milking process from Figure 8. In this cleaning process, the second filter component 154 of the two filter components 153, 154 in each of the double filters is flowed through. Since the filter components 153, 154 of the double filter are disposable items, it is not necessary to clean a used filter component 153, 154. However, it may be sensible to subject a new filter component 153, 154 to be used to a cleaning operation first, before allowing milk to flow through it. Therefore, it may be the case that when the first filter component 153 of a double filter for filtering milk is used, the second filter component 154 is cleaned with cleaning fluid at a suitable point in time. By contrast with the case where the automatically? cleanable milk filters are used, there is no reason to change the flow direction through the filter components 153, 154 in this case. As has already been mentioned in connection with the filter device with the automatically cleanable milk filters, simultaneously using each of the filter units 151a, 151b, 151c, 151 d at one or more points in time during the cleaning process is possible, but it is not essential in the context of the invention.

[0049] Figures 10-13 relate to successive situations in which cleaning fluid flows through the second filter component 154 of the first filter unit 151a while the other filter units 151b, 151c, 151 d are not being used, cleaning fluid flows through the second filter component 154 of the second filter unit 151b while the other filter units 151a, 151c, 151 d are not being used, cleaning fluid flows through the second filter component 154 of the third filter unit 151c while the other filter units 151a, 151 b, 151 d are not being used, and cleaning fluid flows through the second filter component 154 of the fourth filter unit 151 d while the other filter units 151a, 151b, 151c are not being used. As has already been noted earlier in connection with the filter device with the automatically cleanable milk filters, through-flow of only a limited number of the total number of filter units 151a, 151 b, 151c, 151d results in the fluid having a more powerful action on the respective filter component 153, 154 of that limited number than would be the case if all filter units 151a, 151b, 151c, 151 d were to be used.

[0050] Generally, it is the case that each of the filter units 151a, 151b, 151c, 151d has a functional filter surface. In the case of the automatically cleanable milk filters, the functional filter surface of each filter unit 151a, 151 b, 151c, 151 d is a surface of the filter component 152 which is configured to come into contact with a flow of milk and to then have a filtering effect on the milk. In the case of the double filters, each of the two filter components 153, 154 has such a surface and the functional filter surface of each filter unit 151a, 151b, 151c, 151d is one of the respective surfaces.

[0051] The examples to which Figures 2-13 relate are examples of a possibility where, during a cleaning process, cleaning fluid is passed through the functional filter surface of fewer filter units 151a, 151 b, 151c, 151 d than the total number thereof. This does not alter the fact that the invention also relates to a possibility where, during a cleaning process, a limited part of the functional filter surface of each of the filter units is used. This possibility may be achieved, for example, using means to close off a part of a surface of a respective filter component 152, 153, 154 which can be flowed through to through-flow. The invention may be summarized as follows. In the field of transporting and filtering milk, a milk-transporting line 111 for transporting milk and a filter device 150 for filtering the milk in the milk-transporting line 111 are used in a milking system 100. The filter device 150 comprises an assembly of at least two filter units 151a, 151 b, 151c, 151d, through which milk can flow, with each of the filter units 151a, 151b, 151c, 151d having a functional filter surface. In a cleaning process, cleaning fluid is passed through a limited part of a sum of the respective functional filter surfaces of the filter units151a, 151 b, 151c, 151d, so that a locally intensified cleaning operation may be realised, that is to say, cleaning takes place with greater force than would be the case if a cleaning fluid were to be passed through the total sum of the respective functional filter surfaces of the filter units 151a, 151 b, 151c, 151d.

Claims

CLAIMS1. Milking system (100), comprising: a milk-transporting line (111) for transporting milk; a filter device (150) for filtering the milk in the milk-transporting line (111), which filter device (150) comprises an assembly of at least two filter units (151 ; 151a, 151b, 151c, 151d) through which milk is able to flow simultaneously during the milking operation, wherein each of the filter units (151 ; 151a, 151b, 151c, 151d) has a functional filter surface and the assembly has a sum of the respective functional filter surfaces of the filter units; and an operating system (130, 155) for operating the filter device (150) which is configured to cause cleaning fluid to be passed through a limited part of said sum of the respective functional filter surfaces of the filter units (151 ; 151a, 151 b, 151c, 151d) during cleaning.

2. Milking system (100) according to Claim 1 , wherein the operating system (130, 155) is configured to cause cleaning fluid to be passed through the functional filter surface of fewer filter units (151 ; 151a, 151 b, 151c, 151 d) than the total number thereof, or a limited part of the functional filter surface of each of the filter units (151 ; 151a, 151b, 151c, 151d).

3. Milking system (100) according to Claim 1 or 2, wherein the operating system (130, 155) comprises a valve system (155) for regulating flows of fluid through the filter device (150), and a control unit (130) which is configured for actuating the valve system (155).

4. Milking system (100) according to Claim 3, wherein the control unit (130) is configured to bring about at least one setting of the valve system (155) in which a flow of cleaning fluid through only a limited number of the filter units (151 ; 151a, 151 b, 151c, 151 d) is possible.

5. Milking system (100) according to Claim 3 or 4, wherein the control unit (130) is configured to bring about at least one setting of the valve system (155) in which a flow of cleaning fluid through only one of the filter units (151 ; 151a, 151b, 151c, 151d) is possible.

6. Milking system (100) according to one of Claims 3-5, wherein the control unit (130) is configured to bring about a succession of at least two different settings of the valve system (155) in which a flow of cleaning fluid through in each case one or more different filter units (151 ; 151a, 151 b, 151c, 151d) is possible.

7. Milking system (100) according to one of Claims 3-6, wherein at least one of the filter units (151 ; 151a, 151 b, 151c, 151 d) comprises a double filter with two filter components (153, 154), and wherein the valve system (155) is configured simultaneously to allow a flow of fluid to one filter component (153, 154) to pass through, and to block a flow of fluid to the other filter component (153, 154).

8. Milking system (100) according to one of Claims 1-7, wherein the operating system (130, 155) is also configured to bring about that cleaning fluid is passed through the total sum of the respective functional filter surfaces of the filter units (151 ; 151a, 151b, 151c, 151d).

9. Milking system (100) according to one of Claims 1-8, in which the operating system (130, 155) is also configured to bring about that cleaning fluid is passed through the filter device (150) in a direction which is opposite to the direction of a milk flow through the filter device (150).

10. Milking system (100) according to one of Claims 1-9, wherein at least one of the filter units (151 ; 151a, 151b, 151c, 151d) comprises a fixed and durable filter component (152) which is configured to be cleaned from the soiling caused by the milk from time to time.

11. Milking system (100) according to one of Claims 1-10, wherein at least one of the filter units (151; 151a, 151b, 151c, 151d) comprises a disposable filter component (153, 154).

12. Milking system (100) according to one of Claims 1-11 , comprising at least two milking devices (102) for milking dairy animals, each provided with a milk line (104), wherein the respective milk line (104) of at least two of the milking devices (102) is attached to the milk-transporting line (111).

13. Method for performing a cleaning operation in a milking system (100) which comprises the following: a milk-transporting line (111) for transporting milk; and a filter device (150) for filtering the milk in the milk-transporting line (111), which filter device (150) comprises an assembly of at least two filter units (151 ; 151a, 151b, 151c, 151d) through which milk is able to flow simultaneously during the milking operation, wherein each of the filter units (151 ; 151a, 151b, 151c, 151d) has a functional filter surface and the assembly has a sum of the respective functional filter surfaces of the filter units; wherein the method comprises the following: passing cleaning fluid through a limited part of said sum of the respective functional filter surfaces of the filter units (151 ; 151a, 151b, 151c, 151d) during cleaning.

14. Method according to Claim 13, wherein cleaning fluid is passed through the functional filter surface of fewer filter units (151 ; 151a, 151b, 151c, 151d) than the total number thereof, or a limited part of the functional filter surface of each of the filter units (151; 151a, 151b, 151c, 151d).

15. Method according to Claim 13 or 14, wherein the milking system comprises a valve system (155) for regulating flows of fluid through the filter device (150), and wherein at least one setting of the valve system (155) is brought about in which a flow of cleaning fluid through only a limited number of the filter units (151; 151a, 151b, 151c, 151d) is possible.

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