System for storing and cooling milk, milking system, and method for cooling milk

Abstract

A system for storing and cooling milk includes a cooling tank to store milk, a first sensor monitoring the filling level of milk in the cooling tank, and a cooling system cooling the milk in the cooling tank including a cooling device, a second sensor, and a control device. The cooling device includes an evaporator, a varying-capacity modulated scroll compressor connected with its suction side to the evaporator, a condenser connected to the high pressure side of the compressor, and an expansion valve interconnected between the condenser and the evaporator. The second sensor monitors a parameter indicative of the pressure at the suction side of the compressor. The control device is operatively connected to the first sensor to receive the monitored filling level, the second sensor to receive the monitored parameter, and the compressor to control the capacity thereof in response to the monitored filling level and the monitored parameter.

Claims

1. A system (11) for storing and cooling milk comprising: a cooling tank (12) configured to store milk (13); a first sensor (15) monitoring a filling level (L) of milk in the cooling tank; a cooling system cooling the milk in the cooling tank, the cooling system comprising a cooling device (16) comprising an evaporator (19) in heat exchange contact with at least a portion of the bottom surface (12a) of the cooling tank, a compressor (20) connected by a suction side (20a) thereof to the evaporator, the compressor having a varying capacity that is controllable, the compressor being a capacity-modulated scroll compressor, the capacity being controllable by changing the modulation of the compressor, a condenser (21) connected to the high pressure side (20b) of the compressor, and an expansion valve (22) interconnected between the condenser and the evaporator, the evaporator, the compressor, the condenser, and the expansion valve forming a closed circuit, in which a refrigerant is able to be circulated, a second sensor (17) monitoring a parameter indicative of the pressure (P) or temperature at the suction side of the compressor or in the evaporator, and a control device (18) operatively connected (i) to the first sensor to receive the monitored filling level of milk in the cooling tank, (ii) to the second sensor to receive the monitored parameter, and (iii) to the compressor to control the capacity thereof in response to the monitored filling level of milk in the cooling tank and the monitored parameter, the control device controlling the capacity of the compressor by changing the modulation of the compressor such that the pressure or temperature at the suction side of the compressor or in the evaporator is regulated towards a first desired value (P.sub.1TH) when the monitored filling level of milk in the cooling tank is below a first threshold level (L.sub.TH); and a temperature sensor sensing a cooling tank temperature of the milk in the cooling tank, wherein the control device controls the compressor in response to the sensed temperature when the monitored filling level of milk in the cooling tank is above the first threshold level.

2. The system of claim 1, wherein the first desired value (P.sub.1TH) is a pressure at which the refrigerant has a boiling temperature of between about 5 and +3 C.

3. The system of claim 1, wherein the first desired value (P.sub.1TH) is a pressure at which the refrigerant has a heat exchange capacity that ensure that milk in the cooling tank does not freeze even when there are only small amounts of milk therein.

4. The system of claim 1, further comprising an agitator (14) within the cooling tank agitating milk therein, the agitator requiring the filling level of milk in the cooling tank to be above the first threshold level (L.sub.TH) to be able to agitate the milk.

5. The system of claim 1, wherein the control device controls the compressor in response to the sensed temperature such that the compressor is only run intermittently and then at full capacity.

6. The system of claim 1, wherein the control device controls the capacity of the compressor such that the pressure or temperature at the suction side of the compressor or in the evaporator is regulated towards a second desired value (P.sub.2TH) when the monitored filling level of milk in the cooling tank is above the first threshold level, wherein the second desired value is lower than the first desired value.

7. The system of claim 6, wherein the second desired value (P.sub.2TH) is a pressure at which the refrigerant has a boiling temperature of between about 10 and 0 C.

8. The system of claim 1, wherein the control device controls the capacity of the compressor such that the pressure or temperature at the suction side of the compressor or in the evaporator is regulated towards a second desired value (P.sub.2TH) when the monitored filling level of milk in the cooling tank is above the first threshold level, but below a second threshold level (L.sub.2TH), and controls the compressor in a different manner when the monitored filling level of milk in the cooling tank is above the second threshold level.

9. The system of claim 8, further comprising a temperature sensor senses a cooling tank temperature of the milk in the cooling tank, wherein the control device controls the compressor in response to the sensed temperature when the monitored filling level of milk in the cooling tank is above the second threshold level.

10. The system of claim 8, wherein the control device controls the capacity of the compressor such that the pressure or temperature at the suction side of the compressor or in the evaporator is regulated towards a third desired value (.sub.P3TH) when the monitored filling level of milk in the cooling tank is above the second threshold level, and wherein the third desired value is lower than the second desired value.

11. A milking system (31) comprising: a milking device (32) configured to milk animals; and the system (11) for storing and cooling milk of claim 1 connected to the milking device to collect milk as milked by the milking device.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 illustrates, schematically, in side view, main parts of a system for storing and cooling milk according to one embodiment.

(2) FIG. 2 illustrates, schematically, in a block scheme, a milking system comprising the system for storing and cooling milk of FIG. 1.

(3) FIGS. 3 and 4 are each a schematic flow scheme of a method for cooling milk in a cooling tank according to a respective embodiment.

DETAILED DESCRIPTION OF EMBODIMENTS

(4) FIG. 1 illustrates, schematically, in side view, main parts of a system 11 for storing and cooling milk according to one embodiment.

(5) The system 11 for storing and cooling milk comprises a cooling tank 12 provided to store milk 13, a first sensor 15 provided to monitor the filling level L of milk in the cooling tank 12, and a cooling arrangement for cooling the milk in the cooling tank 12 comprising a cooling device 16, a second sensor 17, and a control device 18.

(6) The first sensor 15 may be a sensor provided to measure the filling level L of milk in the cooling tank 12 indirectly, e.g. by means of measuring the amount of milk transferred to the cooling tank 12. The first sensor 15 may e.g. be a milk flow sensor (e.g. arranged upstream of the cooling tank), a level sensor, a threshold level sensor, or a float switch. It may be provided to monitor the exact filling level L of milk in the cooling tank 12 at each instance to provide a reading at each instance, or it may be provided to only check whether the filling level exceeds a threshold or not. In the latter case, the first sensor 15 may be implemented as fixedly located optical sensor.

(7) The cooling device comprises an evaporator 19, a compressor 20 connected with its suction side 20a to the evaporator 19, a condenser 21 connected to the high pressure side 20b of the compressor 20, and an expansion valve 22 interconnected between the condenser 21 and the evaporator 19, thereby forming a closed circuit, in which a refrigerant can be circulated.

(8) The evaporator 19 is in heat exchange contact with at least a portion of the bottom surface 12a of the cooling tank 12.

(9) The compressor 20 has a controllable varying capacity. It may be a capacity modulated scroll compressor, wherein the capacity can be controlled by means of controlling the modulation of the compressor 20. A higher modulation corresponds to a higher pump capacity, and a lower modulation corresponds to a lower pump capacity.

(10) The compressor 20 may be a scroll compressor having two scroll members and a biasing chamber which contains a pressurized fluid. The pressurized fluid within the chamber biases the two scroll members together. A valve assembly is in communication with this biasing chamber and releases the pressurized fluid on demand to remove the load, biasing the two scroll members together. When the biasing load is removed, the two scroll members separate, creating a leakage path between discharge and suction to reduce the capacity of the scroll compressor. Such kind of scroll compressor is commercially available from Copeland Corporation and is patented through U.S. Pat. No. 6,821,092 B1, the contents of which being hereby incorporated by reference.

(11) The second sensor 17 is provided to monitor a parameter indicative of the pressure P at the suction side 20a of the compressor 20. In one version, the second sensor 17 is a pressure sensor.

(12) The control device 18 is operatively connected (i) to the first sensor 15 to receive the monitored filling level L of milk 13 in the cooling tank 12, (ii) to the second sensor 17 to receive the monitored parameter indicative of the pressure P at the suction side 20a of the compressor 20, and (iii) to the compressor 20 to control the capacity thereof by means of changing the modulation of the compressor 20 in response to the monitored filling level L of milk 13 in the cooling tank 12 and the monitored parameter indicative of the pressure P at the suction side 20a of the compressor 20.

(13) Alternatively, the second sensor 17 may provided to monitor a parameter indicative of the pressure P in the evaporator 19 wherein the control device 18 is configured to control the capacity thereof by means of changing the modulation of the compressor 20 in response to the monitored parameter indicative of the pressure P in the evaporator 19.

(14) Yet alternatively, the second sensor 17 may be a temperature sensor provided to monitor a parameter indicative of the temperature at the suction side 20a of the compressor 20 or in the evaporator 19 wherein the control device 18 is configured to control the capacity thereof by means of changing the modulation of the compressor 20 in response to the monitored parameter indicative of the temperature at the suction side 20a of the compressor 20 or in the evaporator 19.

(15) The embodiments below can thus be modified to take the alternatives above into account.

(16) The control device 18 is configured to retrieve a first threshold level L1.sub.TH, to repeatedly compare the monitored filling level L of milk 13 in the cooling tank 12 with the first threshold level L1.sub.TH, and to control the capacity of the compressor 20 such that the pressure P at the suction side 20a of the compressor 20 is regulated towards a first desired value P.sub.1TH when the monitored filling level L of milk 13 in the cooling tank 12 is below the first threshold level L1.sub.TH. The first desired value P.sub.1TH of the pressure may set to be a pressure, at which the refrigerant has a boiling temperature of between about 5 and +3 C. , preferably between about 3 and +1 C., more preferably between about 2 and 0 C. and most preferably about 1 C.3. The first desired value P.sub.1TH of the pressure may be set to a pressure, at which the refrigerant has a heat exchange capacity, which ensure that milk in the cooling tank 12 does not freeze even when there are only small amounts of milk therein. The first desired value P.sub.1TH of the pressure may thus be set by based on experimental results.

(17) In one embodiment, the system 11 comprises a temperature sensor (not illustrated) for sensing the temperature of the milk L in the cooling tank 12, wherein the control device 18 is configured to control the compressor 20 in response to the sensed temperature when the monitored filling level of milk in the cooling tank is above the first threshold level. The control device may be configured to control the compressor in response to the sensed temperature such that the compressor is only run intermittently and then at full capacity.

(18) In an alternative embodiment, the control device 18 may be configured to control the capacity of the compressor 20 such that the pressure P at the suction side 20a of the compressor 20 is regulated towards a second desired value P.sub.2TH of the pressure P at the suction side 20a of the compressor 20 when the monitored filling level L of milk 13 in the cooling tank 12 is above the first threshold level L1.sub.TH.

(19) Preferably, the second desired value P.sub.2TH of the pressure is lower than the first desired value P.sub.1TH. The second desired value P.sub.2TH of the pressure may be a pressure, at which the refrigerant has a boiling temperature of between about 10 and 0 C., preferably between about 8 and 2 C., and most preferably between about 6 and 4 C.

(20) The system 11 for storing and cooling milk may comprise an agitator arrangement 14 within the cooling tank 12 for agitating milk 13 therein, wherein the agitator arrangement 14 requires the filling level L of milk 13 in the cooling tank 12 to be above the threshold level .sub.L1TH to be capable of agitating the milk 13.

(21) In one embodiment the control device 18 is configured to retrieve a second threshold level L.sub.2TH, to repeatedly compare the monitored filling level L of milk 13 in the cooling tank 12 with the second threshold level L.sub.2TH, to control the capacity of the compressor 12 such that the pressure P at the suction side 20a of the compressor 20 is regulated towards the second desired value P.sub.2TH when the monitored filling level L of milk 13 in the cooling tank 12 is above the first threshold level L.sub.1TH, but below the second threshold level L.sub.2TH, and to control the compressor 20 in a different manner when the monitored filling level L of milk 13 in the cooling tank 12 is above the second threshold level L.sub.2TH.

(22) The system 11 may comprise a temperature sensor (not illustrated) for sensing the temperature of the milk L in the cooling tank 12, wherein the control device 18 may be configured to control the compressor 20 in response to the sensed temperature when the monitored filling level of milk in the cooling tank is above the second threshold level.

(23) Alternatively, the control device 18 may be configured to control the capacity of the compressor 20 such that the pressure P at the suction side 20a of the compressor 20 is regulated towards a third desired value P.sub.3TH when the monitored filling level L of milk 13 in the cooling tank 12 is above the second threshold level L2.sub.TH, wherein the third desired value P.sub.3TH is lower than the second desired value P.sub.2TH.

(24) In another embodiment, the second sensor 17 is dispensed with, and the control device 18 is (i) operatively connected to the first sensor 15 to receive the monitored filling level L of milk 13 in the cooling tank 12, (ii) configured to retrieve a threshold level L.sub.TH and to repeatedly compare the monitored filling level L of milk 13 in the cooling tank 12 with the first threshold level, and (iii) operatively connected to the compressor 20 to control the capacity thereof in response to the monitored filling level L of milk 13 in the cooling tank 12 such that the capacity is kept on a first level, such as e.g. between 20 and 60% of a maximum capacity, when the monitored filling level of milk 13 in the cooling tank 12 is below the threshold level L.sub.TH and on a second level, such as e.g. 100% of the maximum capacity, when the monitored filling level of milk 13 in the cooling tank 12 is above the threshold level L.sub.TH.

(25) The control device 18 may comprise input means, through which the capacity, at least on the first level, can be set by an operator.

(26) If the system 11 for storing and cooling milk may comprise an agitator arrangement 14 within the cooling tank 12 for agitating milk 13 therein, the agitator arrangement 14 may require the filling level of milk 13 in the cooling tank 12 to be above the threshold level L.sub.TH to be capable of agitating the milk 13.

(27) FIG. 2 illustrates, schematically, in a block scheme, a milking system 31 comprising the system for storing and cooling milk of FIG. 1.

(28) The milking system 31 comprises a milking device 32 for milking animals and any embodiment of the system 11 for storing and cooling milk as disclosed herein connected to the milking device 32 to collect milk as milked by the milking device 32.

(29) FIG. 3 is a schematic flow scheme of an embodiment of a method for cooling milk in a cooling tank by a cooling device as disclosed above. According to the method, the filling level L of milk in the cooling tank is, in a step 41, monitored and the monitored filling level of milk in the cooling tank is, in a step 42, repeatedly compared with a threshold level L.sub.TH. When the monitored filling level of milk in the cooling tank is below the threshold level L.sub.TH, the capacity of the compressor is, in a step 43, controlled in a first cooling scheme, and when the monitored filling level of milk in the cooling tank is above the threshold level, the capacity of the compressor is, in a step 44, controlled in a second cooling scheme different from the first cooling scheme.

(30) In the first cooling scheme, the capacity of the compressor may be controlled such that the pressure at the suction side of the compressor is regulated towards a first desired value P.sub.1TH.

(31) In the second cooling scheme, the compressor may be controlled in response to a sensed temperature or the capacity of the compressor may be controlled such that the pressure at the suction side of the compressor is regulated towards a second desired value P.sub.2TH. The capacity of the compressor may be controlled by a PID controller. Preferably, the second desired value P.sub.2TH is lower than the first desired value P.sub.1TH.

(32) The above steps may be repeated constantly during the cooling of the milk in the cooling tank, such that the capacity of the compressor is, in each instant, controlled in dependence on the monitored filling level L of milk in the cooling tank and the monitored parameter indicative of the pressure P at the suction side of the compressor.

(33) FIG. 4 is a schematic flow scheme of an embodiment of a method for cooling milk in a cooling tank by a cooling device as disclosed above. According to the method, the filling level L of milk in the cooling tank is, in a step 51, monitored and the monitored filling level of milk in the cooling tank is, in a step 52, repeatedly compared with a threshold level L.sub.TH. When the monitored filling level of milk in the cooling tank is below the threshold level L.sub.TH, the capacity of the compressor is, in a step 53, kept on a first level, such as e.g. 20-60% of a maximum capacity, and when the monitored filling level of milk in the cooling tank is above the threshold level L.sub.TH, the capacity of the compressor is, in a step 54, kept on a second level, such as e.g. 100% of the maximum capacity.

(34) Preferably, the second capacity level of is higher than the first capacity level. The capacity of the compressor can, at least on the first level, be set by an operator at installation of the cooling device.

(35) The above steps may be repeated constantly during the cooling of the milk in the cooling tank, such that the capacity of the compressor is, in each instant, controlled in dependence on the monitored filling level of milk in the cooling tank.

(36) Further, the embodiments of methods for cooling milk as disclosed above with reference to FIGS. 3 and 4 may be further modified to encompass variants and embodiments, which correspond to those disclosed above with respect to FIGS. 1 and 2.

(37) The above embodiments are not limiting but only exemplifying the claimed systems and methods.