MILK-FLOW CONTROL UNIT, COMPUTER-IMPLEMENTED METHOD FOR CONTROLLING A FLOW OF MILK, COMPUTER PROGRAM AND NON-VOLATILE DATA CARRIER

Abstract

A control unit, computer-implemented method, and computer program for controlling a milk transport and cooling apparatus where a flow of milk is controlled from a balance tank to a storage tank, based on a temperature-indicating signal measuring a temperature of the flow of milk before entering the storage tank, and a level-indicating signal reflecting a milk level in the balance tank in relation to low- and high-threshold levels respectively, such that the control unit generates a first control signal controlling the speed of the milk pump based on the temperature-indicating signal when the level-indicating signal is within low- and high-threshold levels respectively, and can also generate a second control signal controlling a capacity of a chiller based on the temperature-indicating signal with respect to an uninterrupted time period.

Claims

1. A control unit (110) for controlling a flow of milk (F) through a cooling system (170), from a balance tank (120) that receives an input (M.sub.IN) of milk extracted from milking animals to a storage tank (130) that stores the milk, the control unit (110) being configured to: receive a temperature-indicating signal (T) from a temperature sensor (140) measuring a temperature of the flow of milk (F) between the cooling system (170) and the storage tank (130); receive a level-indicating signal (s(L.sub.TH:H.sub.TH)) from at least one sensor configured to register a milk level (L) in the balance tank (120) in relation to low- and high-threshold levels respectively; and generate a first control signal (C1) to a milk pump (150) of the cooling system (170) arranged to cause the flow of milk (F) to be pumped out from the balance tank (120), said first control signal (C1) generated based on the temperature-indicating signal (T), wherein the control unit (110) controls a speed of the milk pump (150) via the first control signal (C1) based exclusively on the temperature-indicating signal (T) if the level-indicating signal (s(L.sub.TH:H.sub.TH)) received at the control unit (110) reflects that the milk level (L) in the balance tank (120) is between the low-threshold level (L.sub.TH) and the high-threshold level (H.sub.TH).

2. The control unit (110) according to claim 1, further configured to control the milk pump (150), via the first control signal (C1), to cause the flow of milk (F) to be pumped out from the balance tank (120) at a predetermined high speed (F.sub.HI) if the level-indicating signal (s(L.sub.TH:H.sub.TH)) received at the control unit (110) reflects that the milk level (L) in the balance tank (120) is above or equal to the high-threshold level (H.sub.TH).

3. The control unit (110) according to claim 2, wherein the predetermined high speed (F.sub.HI) represents a highest possible pump speed for the milk pump (150).

4. The control unit (110) according to claim 2, further configured to generate a second control signal (C2) to the cooling system (170) based on the temperature-indicating signal (T), and to control a cooling capacity of the cooling system (170) via the second control signal (C2) to increase if the temperature-indicating signal (T) received at the control unit (110) reflects a milk temperature above a set temperature (T.sub.SET).

5. The control unit (110) according to claim 4, further configured to control the cooling capacity of the cooling system (170) via the second control signal (C2) to decrease if the temperature-indicating signal (T) received at the control unit (110) reflects a milk temperature below the set temperature (T.sub.SET).

6. The control unit (110) according to claim 1, further configured to control the milk pump (150) to cause the flow of milk (F) to be pumped out from the balance tank (120) at a predetermined low speed (F.sub.LO) if the level-indicating signal (s(L.sub.TH:H.sub.TH)) received at the control unit (110) reflects that the milk level (L) in the balance tank (120) is below or equal to the low-threshold level (L.sub.TH).

7. The control unit (110) according to claim 1, further configured to control the milk pump (150) to become inactive if the level-indicating signal (s(L.sub.TH:H.sub.TH)) received at the control unit (110) reflects that the milk level (L) in the balance tank (120) is below or equal to the low-threshold level (L.sub.TH).

8. The control unit (110) according to claim 1, wherein the control unit (110) controls the milk pump (150), via the first control signal (C1), to cause the milk flow (F) to be pumped out from the balance tank (120) at: a predetermined nominal speed (F.sub.NOM) if the temperature-indicating signal (T) received at the control unit (110) indicates a milk temperature within a predefined interval (T.sub.R) from a set temperature (T.sub.SET), an elevated speed (F.sub.ELVD) above the predetermined nominal speed (F.sub.NOM) if the temperature-indicating signal (T) received at the control unit (110) indicates a milk temperature below said predefined interval (T.sub.R), and a lowered speed (F.sub.LWD) below the predetermined nominal speed (F.sub.NOM) if the temperature-indicating signal (T) received at the control unit (110) indicates a milk temperature above said predefined interval (T.sub.R).

9. The control unit (110) according to claim 1, wherein the cooling system (170) comprises a heat exchanger (160) configured to transfer heat energy from the flow of milk (F) to a cooling medium (C) that circulates in a chiller (167) by means of a coolant pump (165) that operates in response to a second control signal (C2), and wherein the control unit (110) is further configured to control the coolant pump (165), via the second control signal (C2), based on the temperature-indicating signal (T) so that: a flow of the cooling medium (C) and/or the cooling capacity of the chiller (167) increases if the temperature-indicating signal (T) received at the control unit (110) indicates a milk temperature above a predefined interval (T.sub.R) from a set temperature (T.sub.SET) during a first uninterrupted period, and the flow of the cooling medium (C) and/or the cooling capacity of the chiller (167) decreases if the temperature-indicating signal (T) received at the control unit (110) indicates a milk temperature below said predefined interval (T.sub.R) from the set temperature (T.sub.SET) during a second uninterrupted period.

10. A computer-implemented method for controlling a flow of milk (F) through a cooling system (170), from a balance tank (120) that receives an input (M.sub.IN) of milk extracted from milking animals to a storage tank (130) that stores the milk, the method comprising: receiving a temperature-indicating signal (T) from a temperature sensor (140) measuring a temperature of the flow of milk (F) between the cooling system (170) and the storage tank (130); receiving a level-indicating signal (s(L.sub.TH:H.sub.TH)) from at least one sensor configured to register a milk level (L) in the balance tank (120) in relation to low- and high-threshold levels respectively; generating a first control signal (C1) to a milk pump (150) of the cooling system (170), the milk pump (150) arranged to cause the flow of milk (F) to be pumped out from the balance tank (120), said first control signal (C1) generated based on the temperature-indicating signal (T); determining that the received level-indicating signal (s(L.sub.TH:H.sub.TH)) reflects that the milk level (L) in the balance tank (120) is between the low-threshold level (L.sub.TH) and the high-threshold level (H.sub.TH); and subsequent to said determining, controlling a speed of the milk pump (150) via the first control signal (C1) based exclusively on the temperature-indicating signal (T).

11. The method according to claim 10, further comprising: determining that the received level-indicating signal (s(L.sub.TH:H.sub.TH)) reflects that the milk level (L) in the balance tank (120) is above or equal to the high-threshold level (H.sub.TH), and subsequently controlling the milk pump (150) via the first control signal (C1), to cause the flow of milk (F) to be pumped out from the balance tank (120) at a predetermined high speed (F.sub.HI).

12. The method according to claim 11, wherein the predetermined high speed (F.sub.HI) represents a highest possible pump speed for the milk pump (150).

13. The method according to claim 11, further comprising: determining that the temperature-indicating signal (T) reflects a milk temperature above a set temperature (T.sub.SET), and subsequently controlling a cooling capacity of the cooling system (170), via a second control signal (C2) based on the temperature-indicating signal (T), such that the cooling capacity of the cooling system (170) is increased.

14. The method according to claim 13, further comprising: determining that the temperature-indicating signal (T) reflects a milk temperature below the set temperature (T.sub.SET), and subsequently controlling the cooling capacity of the cooling system (170), via the second control signal (C2), such that the cooling capacity of the cooling system (170) is decreased.

15. The method according to claim 10, comprising: determining that the received level-indicating signal (s(L.sub.TH:H.sub.TH)) reflects that the milk level (L) in the balance tank (120) is below or equal to the low-threshold level (L.sub.TH), and subsequently controlling the milk pump (150) via the first control signal (C1), to cause the flow of milk (F) to be pumped out from the balance tank (120) at a predetermined low speed (F.sub.LO).

16. The method according to claim 10, determining that the received level-indicating signal (s(L.sub.TH:H.sub.TH)) reflects that the milk level (L) in the balance tank (120) is below or equal to the low-threshold level (L.sub.TH), and subsequently controlling the milk pump (150) to become inactive.

17. The method according to claim 10, wherein the first control signal (C1) is generated such that the milk flow (F) is caused to be pumped out from the balance tank (120) at: a predetermined nominal speed (F.sub.NOM) if the temperature-indicating signal (T) indicates a milk temperature within a predefined interval (T.sub.R) from a set temperature (T.sub.SET), an elevated speed (F.sub.ELVD) above the predetermined nominal speed (F.sub.NOM) if the temperature-indicating signal (T) indicates a milk temperature below said predefined interval (T.sub.R), and a lowered speed (F.sub.LWD) below the predetermined nominal speed (F.sub.NOM) if the temperature-indicating signal (T) indicates a milk temperature above said predefined interval (T.sub.R).

18. The method according to claim 10, wherein the cooling system (170) a heat exchanger (160) configured to transfer heat energy from the flow of milk (F) to a cooling medium (C) that circulates in a chiller (167) by means of a coolant pump (165) that operates in response to a second control signal (C2), and the method further comprises: generating the second control signal (C2) based on the temperature-indicating signal (T) so that: a flow of the cooling medium (C) and/or the cooling capacity of the chiller (167) increases if the temperature-indicating signal (T) indicates a milk temperature above a predefined interval (T.sub.R) from a set temperature (T.sub.SET) during a first uninterrupted period, and the flow of the cooling medium (C) and/or the cooling capacity of the chiller (167) decreases if the temperature-indicating signal (T) indicates a milk temperature below said predefined interval (T.sub.R) from the set temperature (T.sub.SET) during a second uninterrupted period.

19. A computer-readable non-transitory storage medium having stored thereon a computer program (317) readable by a processing unit (315), the computer program (317) comprising instruction code that when executed by the processing unit causes the processing unit to carry out the method according to claim 10.

20. (canceled)

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The invention is now to be explained more closely by means of preferred embodiments, which are disclosed as examples, and with reference to the attached drawings.

[0021] FIG. 1 schematically illustrates a milk handling system including a control unit according to one embodiment of the invention;

[0022] FIG. 2 shows a diagram exemplifying a relationship between a set milk flow rate, a temperature of the milk and a level of milk in a balance tank according to one embodiment of the invention;

[0023] FIG. 3 shows a block diagram of the control unit according to the invention; and

[0024] FIG. 4 illustrates, by means of a flow diagram, the general method according to a preferred embodiment of the invention.

DETAILED DESCRIPTION

[0025] In FIG. 1, we see a schematic illustration of a milk handling system that includes a control unit 110 according to one embodiment of the invention.

[0026] The control unit 110 is arranged to control a flow of milk F through a cooling system 170 between a balance tank 120 and a storage tank 130. The storage tank 130 is adapted to accumulate milk that has been collected during a relatively long period, namely between consecutive pickups of the milk for further transport to a dairy or similar facility, which pickups typically occur every 24 or 48 hours. Consequently, the storage tank 130 has a comparatively large capacity. The balance tank 120, on the other hand, has a comparatively low capacity because here the milk is just buffered briefly before being forwarded through the cooling system 170. The balance tank 120 is adapted to receive an input M.sub.IN in the form of milk having been extracted from a number of milking animals. Thus, one or more milking points may feed milk to the balance tank 120 directly or for example via a so-called end unit, or receiver.

[0027] A temperature sensor 140 is arranged on a milk conduit feeding the milk into the storage tank 130. The temperature sensor 140 is configured to measure a temperature of the flow of milk F before entering the storage tank 130. The balance tank 120 contains at least one sensor, here represented by a first sensor 121 and a second sensor 122, which are configured to produce a level-indicating signal s(L.sub.TH:H.sub.TH) reflecting a milk level L in the balance tank 120 in relation to a low-threshold level L.sub.TH and a high-threshold level H.sub.TH respectively. For example, the low-threshold level L.sub.TH may represent 10% of a storage capacity of the balance tank 120 and the high-threshold level H.sub.TH may represent 90% of the storage capacity of the balance tank 120.

[0028] The control unit 110 is configured to receive the temperature-indicating signal T from the temperature sensor 140. The control unit 110 is also configured to receive the level-indicating signal s(L.sub.TH:H.sub.TH) from the at least one sensor 121/122. Based on the temperature-indicating signal T and the level-indicating signal s(L.sub.TH:H.sub.TH), the control unit 110 is configured to generate a first control signal C1 to a milk pump 150 in the cooling system 170, which milk pump 150 is arranged to cause the flow of milk F to be pumped out from the balance tank 120 and through the cooling system 170. Specifically, the first control signal C1 is generated based on the temperature-indicating signal T and the level-indicating signal s(L.sub.TH:H.sub.TH) in such a manner that a speed of the milk pump 150 is controlled by the first control signal C1 based on the temperature-indicating signal T exclusively if the level-indicating signal s(L.sub.TH:H.sub.TH) reflects that the milk level L in the balance tank 120 is between the low-threshold level L.sub.TH and the high-threshold level H.sub.TH. Otherwise, i.e. when the milk level L does not lie within the range given by the low- and high-threshold levels L.sub.TH and H.sub.TH, the first control signal C1 is not based on the temperature-indicating signal T as will be explained below, inter alia with reference to FIG. 2.

[0029] FIG. 2 shows a diagram representing a temperature T of the flow of milk F before entering to the storage tank 130 along the horizontal axis, and a milk level L in the balance tank 120 along the vertical axis.

[0030] According to one embodiment of the invention, the control unit 110 is configured to generate the first control signal C1 such that the milk pump 150 causes the flow of milk F to be pumped out from the balance tank 120 at a predetermined high speed F.sub.HI, say at 80% or more of the milk pump's 150 maximum speed, if the level-indicating signal s(L.sub.TH:H.sub.TH) reflects that the milk level L in the balance tank 120 is above or equal to the high-threshold level H.sub.TH. Namely, if the milk level L is above or equal to the high-threshold level H.sub.TH, there is an imminent risk that the balance tank 120 will be flooded. In such a situation it is important that the milk level L is reduced quickly. Therefore, the predetermined high speed F.sub.HI preferably represents a highest possible pump speed for the milk pump 150 thus accomplishing a quickest possible reduction of the milk level L in the balance tank 120.

[0031] Additionally, it may be preferable if the control unit 110 is configured to generate the first control signal C1 such that the milk pump 150 causes the flow of milk F to be pumped out from the balance tank 120 at a predetermined low speed Fro, say at 20% or less of the milk pump's 150 maximum speed, if the level-indicating signal s(L.sub.TH:H.sub.TH) reflects that the milk level L in the balance tank 120 is below or equal to the low-threshold level L.sub.TH. Namely, otherwise, in such a case, the balance tank 120 might be emptied and undesired air bubbles risk being injected into the milk. It is therefore advantageous that the predetermined low speed Fro represents that the milk pump 150 is inactive, i.e. does not cause any flow of milk at all to be pumped out from the balance tank 120.

[0032] According to one embodiment of the invention, the control unit 110 is configured to generate a second control signal C2 based on the temperature-indicating signal T such that a cooling capacity of the cooling system 170 is increased if the temperature-indicating signal T reflects a milk temperature above a set temperature T.sub.SET of say 3.5 degrees Celsius. This means that the milk pump 150 may be operated at a relatively high, preferably fixed speed, which, in turn, renders it possible to increase a cooling capacity of a chiller 167 and/or a speed of a coolant pump 165 in the cooling system 170 based on the temperature-indicating signal T.

[0033] Analogously, according to another one embodiment of the invention, the control unit 110 is preferably configured to generate the second control signal C2 based on the temperature-indicating signal T such that the cooling capacity of the cooling system 170 is decreased if the temperature-indicating signal T reflects a milk temperature below the set temperature T.sub.SET. Namely, in such a case, energy can be economized by reducing the cooling of the milk.

[0034] According to one embodiment of the invention, the control unit 110 is configured to generate the first control signal C1 based on the temperature-indicating signal T so that the milk flow F is caused to be pumped out from the balance tank 120 at a predetermined nominal speed F.sub.NOM, say around 50% of the milk pump's 150 maximum speed, if the temperature-indicating signal T indicates a milk temperature within a predefined interval T.sub.R from a set temperature T.sub.SET, say between 3 and 5 degrees Celsius. Thus, a steady milk flow F can be fed efficiently through the cooling system 170 into the storage tank 130.

[0035] If the temperature-indicating signal T indicates a milk temperature below the predefined interval T.sub.R, the control unit 110 is configured to generate the first control signal C1 based on the temperature-indicating signal T so that the milk flow F is caused to be pumped out from the balance tank 120 at an elevated speed F.sub.ELVD, i.e. at % or more of the milk pump's 150 maximum speed, above the predetermined nominal speed F.sub.NOM, thus causing the milk to be less cooled while forwarding more milk per unit time into the storage tank 130. It is additionally possible to hereby use the further second control signal C2 to also decrease the speed of the coolant pump 165. In this way, less heat will be taken from the milk.

[0036] If the temperature-indicating signal T indicates a milk temperature above said predefined interval T.sub.R, the control unit 110 is instead configured to generate the first control signal C1 based on the temperature-indicating signal T so that the milk flow F is caused to be pumped out from the balance tank 120 at a lowered speed F.sub.LWD below the predetermined nominal speed F.sub.NOM, i.e. at 50% or less of the milk pump's 150 maximum speed, thus cooling the milk more while passing through the cooling system 170 before entering the storage tank 130. It is also possible to hereby use the further second control signal C2 to increase the speed of the coolant pump 165. In this way, more heat will be taken from the milk.

[0037] According to one embodiment of the invention, the cooling system 170 contains a heat exchanger 160, for example a plate heat exchanger (PHE), which is configured to transfer heat energy from the flow of milk F to a cooling medium C, e.g. containing glycol being circulated in the chiller 167 by means of the coolant pump 165. The coolant pump 165 is adapted to operate in response to a second control signal C2.

[0038] Here, the control unit 110 is further configured to generate the second control signal C2 based on the temperature-indicating signal T so that a flow of the cooling medium C and/or the cooling capacity of the chiller 167 increases, if the temperature-indicating signal T indicates a milk temperature above the predefined interval T.sub.R during a first uninterrupted period, say 60 seconds. Thereby, any excessive milk temperatures may be reduced efficiently.

[0039] Further, if the temperature-indicating signal T indicates a milk temperature below the predefined interval T.sub.R during a second uninterrupted period, say 60 seconds, the control unit 110 is configured generate the second control signal C2 based on the temperature-indicating signal T so that the flow of the cooling medium C and/or the cooling capacity of the chiller 167 decreases. Hence, unnecessary cooling of the milk is avoided and energy is conserved.

[0040] FIG. 3 shows a block diagram of the control unit 110 according to the invention. It is generally advantageous if the controller 110 is configured to effect the above-described procedure in an automatic manner by executing a computer program 317. Therefore, the controller 110 may include a memory unit 316, i.e. non-volatile data carrier, storing the computer program 317, which, in turn, contains software for making processing circuitry in the form of at least one processor 315 in the controller 110 execute the actions mentioned in this disclosure when the computer program 317 is run on the at least one processor 315.

[0041] In order to sum up, and with reference to the flow diagram in FIG. 4, we will now describe the computer-implemented method according to one embodiment of the invention for controlling the flow of milk F through the cooling system 170 between the balance tank 120 and the storage tank 130, where the balance tank 120 receives an input M.sub.IN in the form of milk extracted from a number of milking animals.

[0042] In a first step 410, a temperature-indicating signal T is received from a temperature sensor 140 measuring a temperature of the flow of milk F before entering the storage tank 130. A level-indicating signal s(L.sub.TH:H.sub.TH) is also received in step 410, which level-indicating signal s(L.sub.TH:H.sub.TH) reflects a milk level in the balance tank 120 in relation to low- and high-threshold levels respectively.

[0043] A subsequent step 420 checks if the level-indicating signal s(L.sub.TH:H.sub.TH) reflects that the milk level in the balance tank 120 is within the low- and high-threshold levels; and if so, a step 430 follows. Otherwise, the procedure continues to a step 440.

[0044] In step 430, the milk flow is controlled to a nominal rate by generating the first control signal C1 to the milk pump 150 in the cooling system 170. Thereafter, the procedure loops back to step 410.

[0045] In step 440, it is checked if the level-indicating signal s(L.sub.TH:H.sub.TH) reflects that the milk level in the balance tank 120 is above the high-threshold level; and if so, a step 450 follows. Otherwise, the procedure continues to a step 460.

[0046] In step 450, the milk flow is controlled to a high rate via the first control signal C1 to the milk pump 150. Thereafter, the procedure loops back to step 410.

[0047] In step 460, the milk flow is instead controlled to a low rate via the first control signal C1 to the milk pump 150. Thereafter, the procedure loops back to step 410.

[0048] All of the process steps, as well as any sub-sequence of steps, described with reference to FIG. 4 may be controlled by means of a programmed processor. Moreover, although the embodiments of the invention described above with reference to the drawings comprise processor and processes performed in at least one processor, the invention thus also extends to computer programs, particularly computer programs on or in a carrier, adapted for putting the invention into practice. The program may be in the form of source code, object code, a code intermediate source and object code such as in partially compiled form, or in any other form suitable for use in the implementation of the process according to the invention. The program may either be a part of an operating system, or be a separate application. The carrier may be any entity or device capable of carrying the program. For example, the carrier may comprise a storage medium, such as a Flash memory, a ROM (Read Only Memory), for example a DVD (Digital Video/Versatile Disk), a CD (Compact Disc) or a semiconductor ROM, an EPROM (Erasable Programmable Read-Only Memory), an EEPROM (Electrically Erasable Programmable Read-Only Memory), or a magnetic recording medium, for example a floppy disc or hard disc. Further, the carrier may be a transmissible carrier such as an electrical or optical signal which may be conveyed via electrical or optical cable or by radio or by other means. When the program is embodied in a signal, which may be conveyed, directly by a cable or other device or means, the carrier may be constituted by such cable or device or means. Alternatively, the carrier may be an integrated circuit in which the program is embedded, the integrated circuit being adapted for performing, or for use in the performance of, the relevant processes.

[0049] Variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims.

[0050] The term comprises/comprising when used in this specification is taken to specify the presence of stated features, integers, steps or components. The term does not preclude the presence or addition of one or more additional elements, features, integers, steps or components or groups thereof. The indefinite article a or an does not exclude a plurality. In the claims, the word or is not to be interpreted as an exclusive or (sometimes referred to as XOR). On the contrary, expressions such as A or B covers all the cases A and not B, B and not A and A and B, unless otherwise indicated. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. Any reference signs in the claims should not be construed as limiting the scope.

[0051] It is also to be noted that features from the various embodiments described herein may freely be combined, unless it is explicitly stated that such a combination would be unsuitable.

[0052] The invention is not restricted to the described embodiments in the figures, but may be varied freely within the scope of the claims.