WO2001001052A1

WO2001001052A1 - A control assembly for a refrigeration unit

Info

Publication number: WO2001001052A1
Application number: PCT/US2000/018388
Authority: WO
Inventors: Thomas L. Guy; Darren W. Simmons; Ernest M. Chavana, Jr.
Original assignee: Lancer Partnership, Ltd.
Priority date: 1999-06-30
Filing date: 2000-06-30
Publication date: 2001-01-04
Also published as: AU6070000A

Abstract

An apparatus for cooling a cooling fluid contained in a cooling chamber (27) includes a refrigeration unit (2) and a fan control assembly (30, 35, 37, 40) operatively engaged with the refrigeration unit for controlling the flow of refrigerant through the refrigeration unit. Alternatively, the apparatus for cooling a cooling fluid contained in a cooling chamber includes a refrigeration unit and a flow modulation unit (40, 50) in operative engagement with the refrigeration unit for controlling the flow of refrigerant through the refrigeration unit.

Description

A CONTROL ASSEMBLY FOR A REFRIGERATION UNIT BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to dispensing equipment and, more particularly, but not by way of limitation, to a control assembly for a beverage dispenser refrigeration unit that provides variable temperature/pressure control of refrigerant under various climate conditions.

2. Description of the Related Art

Typically, beverage dispensers include cooling units for cooling beverage fluids, such as a diluent of plain water or carbonated water and beverage flavored syrup, prior to forming and dispensing a desired beverage in that it is highly desirable in the industry to serve drinks at the coldest temperature possible. As such, one cooling unit known in the industry features a cooling fluid bath that includes a cooling chamber disposed within a beverage dispenser. The cooling chamber contains a cooling fluid, which is typically water. The refrigeration unit includes an evaporator having an evaporator coil that extends from the refrigeration unit into the cooling fluid chamber so that the evaporator coil is submerged within the cooling fluid. While the refrigeration unit is in operation, cooling fluid freezes in a slab about the evaporator coil. In effect, the slab of frozen cooling fluid acts as a heat sink, whereby the slab absorbs heat from beverage fluids flowing within respective lines that are submerged within the unfrozen cooling fluid. The unfrozen cooling fluid acts as a medium or "intermediary" for heat exchange in that heat is transferred by the unfrozen cooling fluid from the warm beverage fluids to the frozen slab along a circuitous path of convection.

The refrigeration unit includes a refrigeration line whereby refrigerant flows therethrough. The refrigeration line is integrated with the evaporator coil so that, ultimately, refrigerant flowing through the evaporator coil freezes the cooling fluid in a slab in the manner described above. Refrigerant is pumped through the refrigeration line via a compressor provided by the refrigeration unit.

The refrigeration unit includes a condenser for removing heat from the refrigerant via heat transfer, whereby air surrounding the refrigeration line is cooled by the condenser In particular, cool air acts as a heat sink whereby heat is absorbed from the refrigerant through the refrigeration line to the surrounding air. Typically, a condenser includes a fan for cooling the surrounding air, whereby the fan is driven by a fan motor. Therefore, refrigerant is either heated at a low fan speed or cooled at a high fan speed.

Inasmuch, cooled refrigerant flows from the condenser to the evaporator and across the evaporator coil to thus complete a cyclical path about the refrigeration unit. It should be added that the slab is created from cooling fluid surrounding the evaporator coil as heat is removed from the cooling fluid by the cooled refrigerant flowing through the evaporator coil.

Current design of refrigeration units, however, does not provide for variable temperature/pressure control of refrigerant through the refrigeration line. As such, a lack of variable temperature/pressure control compromises the refrigerating capacity of a refrigeration unit under various climate conditions, especially in "low ambient conditions" where air surrounding a refrigeration line is less than 55 °F. Lack of variable temperature/pressure control at low ambient conditions decreases the mass flow rate of refrigerant through the refrigeration line. The decline in mass flow rate at low ambient conditions, in turn, unfavorably increases the potential for refrigerant to begin accumulating within a condenser instead of in an evaporator - a condition known in the industry as "supercooling" of a condenser. As such, supercooling of the condenser produces misshapen slabs of frozen cooling fluid at an evaporator and, potentially, can freeze up an entire cooling fluid bath. Accordingly, there is a long felt need for a control assembly for a refrigeration unit that provides variable temperature/pressure control of refrigerant under various climate conditions to optimize the refrigerating capacity of the refrigeration unit. SUMMARY OF THE INVENTION

In accordance with the present invention, an apparatus for cooling a cooling fluid contained in a cooling chamber includes a refrigeration unit and a fan control assembly operatively engaged with the refrigeration unit for controlling the flow of refrigerant through the refrigeration unit. The fan control assembly includes a sensor, a control unit, and a fan controller. The sensor is positioned along the refrigeration unit for measuring the flow rate of refrigerant and correspondingly transmitting a measurement signal. The control unit is linked with the sensor for comparing the measurement signal with a desired measurement and correspondingly generating a fan control signal. The fan controller is linked with the control unit for controlling the flow of refrigerant through the refrigeration unit pursuant to the fan control signal. Alternatively, the apparatus for cooling a cooling fluid contained in a cooling chamber includes a refrigeration unit and a flow modulation unit in operative engagement with the refrigeration unit for providing flow control of refrigerant through the refrigeration unit. The flow modulation unit includes a sensor, a control unit, and an expansion device. The sensor is positioned along the refrigeration unit for measuring the flow rate of refrigerant and correspondingly transmitting a measurement signal. The control unit is linked with the sensor for comparing the measurement signal with a desired measurement and correspondingly generating a valve signal. The expansion device is linked with the control unit for controlling flow of refrigerant pursuant to the valve signal. A method for cooling cooling fluid contained in a refrigeration unit includes the steps of linking a control assembly in operative engagement with the refrigeration unit, measuring the flow rate of refrigerant, transmitting a measurement signal, and comparing the measurement signal to a desired measurement with the control unit and correspondingly generating a control signal therefrom. The method further includes the steps of providing a fan in operative engagement with the refrigeration unit and, pursuant to the control signal, controlling the speed of the fan with a fan controller linked to the control unit. Alternatively, the method includes the steps of providing a flow modulation unit including an expansion device linked with the control unit and, pursuant to the control signal, controlling the flow of refrigerant with the expansion device. It is therefore an object of the present invention to provide a method and apparatus that regulates the flow of refrigerant through a refrigeration unit to prevent undesirable "supercooling" of the refrigeration.

Still other objects, features, and advantages of the present invention will become evident to those skilled in the art in light of the following. BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of a control assembly for a beverage dispenser refrigeration unit according to the preferred embodiment featuring a fan control system and a flow modulation system. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT As required, detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention which may be embodied in various forms, the figures are not necessarily to scale, and some features may be exaggerated to show details of particular components or steps. FIG. 1 illustrates a control assembly 1 integrated with a refrigeration unit 2 for a beverage dispenser cooling unit. The preferred cooling unit features a cooling fluid bath that includes a cooling chamber 27 disposed within a beverage dispenser (not shown).

Cooling chamber 27 contains a cooling fluid 25, which is typically water. As shown in FIG. 1, refrigeration unit 2 includes an evaporator 20. In this preferred embodiment, evaporator 20 is a standard beverage dispenser evaporator. Evaporator 20 includes an evaporator coil 22 that extends from the refrigeration unit 2 into the cooling chamber 27 so that the evaporator coil 22 is submerged within the cooling fluid 25. While the refrigeration unit 2 is in operation, cooling fluid freezes in a slab 65 about the evaporator coil 22. In effect, the slab 65 acts as a heat sink whereby the slab 65 absorbs heat from beverage fluids flowing within respective lines that are submerged within the cooling fluid 25 (not shown). The cooling fluid 25 acts as a medium or "intermediary" for heat exchange in that heat is transferred by the cooling fluid 25 from the warm beverage fluids to the slab 25 along a circuitous path of convection. The refrigeration unit 2 includes a refrigeration line 5 whereby refrigerant flows therethrough. The refrigeration line 5 is integrated with the evaporator coil 22 so that, ultimately, refrigerant flowing through the evaporator coil 22 freezes cooling fluid in a slab in the manner described above. As indicated by directional arrow 4, refrigerant is pumped through the refrigeration line 5 via a compressor 10 provided by the refrigeration unit 2. In this preferred embodiment, compressor 10 is a standard beverage dispenser compressor. The refrigeration unit 2 includes a condenser 15 for removing heat from the refrigerant via heat transfer. In this preferred embodiment, condenser 15 is a standard beverage dispenser condenser. Accordingly, while refrigeration line 5 passes through condenser 15, the condenser 15 facilitates heat transfer by cooling air surrounding the refrigeration line 5. In particular, cool air acts as a heat sink whereby heat is absorbed from the refrigerant through the refrigeration line 5 to the surrounding air in the condenser 15. In this preferred embodiment, condenser 15 includes a fan 35 for cooling the surrounding air, whereby the fan 35 is driven by a fan motor 30. Therefore, refrigerant is either heated at a low fan speed or cooled at a high fan speed. Inasmuch, cooled refrigerant flows from the condenser 15 to the evaporator 20.

While passing through the evaporator 20, cooled refrigerant flows through the evaporator coil 22. The slab 65 is thus created from the cooling fluid 25 surrounding the evaporator coil 22 as heat is removed from the cooling fluid 25 by the cooled refrigerant flowing across evaporator coil 22. As a result of heat transfer, refrigerant exits evaporator 20 at a warmer temperature than upon entering. The refrigerant flows from evaporator 20 to compressor 10 to complete a cyclical path about refrigeration unit 2. In this preferred embodiment, the refrigeration line 5, the compressor 10, the condenser 15, and the evaporator 20 define a closed system through which refrigerant flows.

One embodiment of the refrigeration unit 2 includes a growth control system for the slab 65. As such, refrigeration unit 2 provides an array of probes 60 positioned along the slab 65 for detecting the size and the growth rate of the slab 65. The array of probes 60 is operationally linked with the compressor 10 in a manner described in U.S. Patent No. 4,939,908, the disclosure of which is incorporated herein by reference. Accordingly, the array of probes 60 generates a signal that selectively dictates the operation of the compressor

10 in either an "on" or an "off position. Thus, when compressor 10 is in the "on" position, refrigerant is pumped across refrigeration line 5 and slab 65 grows in size such that the perimeters of the slab 65 progress outwardly from the evaporator coil 22. When the array of probes 60 determines that the perimeter of the slab 65 has grown to a sufficient size, a signal is generated therefrom that places the compressor 10 in the "off' position. While the compressor 10 is in the "off' position, refrigerant is not pumped through refrigeration line 5 so that the slab 65 melts and the perimeters of the slab 65 recess inwardly toward the evaporator coil 22. The control assembly 1 includes either a fan control assembly or a flow modulation unit, each for providing variable temperature/pressure control of refrigerant across the refrigeration line 5. In this preferred embodiment, the fan control assembly includes one sensor 45 positioned along the refrigeration line 5 for measuring the mass flow rate of the refrigerant across the refrigeration line 5. Other embodiments contemplate a plurality of sensors in any combination positioned along the refrigeration line 5.

Although those of ordinary skill in the art will recognize other suitable positions,

FIG. 1 illustrates preferred positions along refrigeration line 5 for sensor 45. Specifically, at location 45a sensor 45 is positioned substantially adjacent to the compressor 10 to measure refrigerant discharged from the compressor 10. In a similar manner, at location 45b sensor 45 is positioned substantially adjacent to the condenser 15 to measure refrigerant discharged from the condenser 15. Sensor 45 at either location 45c or 45d is positioned substantially adjacent to the evaporator 20 to measure refrigerant on entering and exiting the evaporator

20, respectively. Mass flow rate is determined by measuring either temperature or pressure of refrigerant at a designated location or locations across the refrigeration line 5. As such, sensor 45 can be a pressure sensor, a temperature sensor, a transducer, a switch or any other recognizable sensor for measuring either temperature or pressure. The fan control assembly includes a control unit 40 linked with the sensor 45 via line

42 for controlling the speed of the fan 35. The control unit 40 in this preferred embodiment is a processor and associated circuitry for providing the processor with the correct DC power levels from the power source 39. The control unit 40 receives a measurement signal generated by the sensor 45, compares the measurement signal to a desired stored measurement, and generates a corresponding fan control signal in accordance with the measured and stored signals. The control unit 40 emits the fan control signal across line 43 for receipt by a fan controller 37. The fan controller 37 controls the speed of the fan 35 by varying the speed of the fan motor 30 that drives fan 35. In particular, fan controller 37 regulates the power delivered across line 44 from a power source 39 to drive the fan motor 30.

In this preferred embodiment, the fan controller 37 is a transducer for variably controlling the speed of the fan 35 based on the fan control signal emitted from the control unit 40. Accordingly, selective control of the speed of the fan 35 provides the refrigeration unit 2 with variable temperature/pressure control in response to various climate conditions experienced by the refrigeration unit 2. Thus, when the air temperature surrounding the refrigeration line 5 in the condenser 15 is unfavorably warm, the fan control system increases the speed of the fan 35 to cool the refrigerant. Similarly, when the air temperature is unfavorably cool, especially in low ambient conditions, the fan control system decreases the speed of the fan 35 to warm the refrigerant, thereby guarding a refrigeration unit from supercooling of a condenser. In short, by continuously adjusting for various climate conditions, the fan control system enables the refrigeration unit 2 to favorably achieve and maintain a steady state heat transfer rate for refrigerant across the refrigeration line 5 and, ultimately, regulate the growth and size of the slab 65.

Illustratively, for example, sensor 45 measures for the mass flow rate of refrigerant flowing into condenser 15 and emits a measurement signal. For this illustration, it should be added that the sensor 45 measures for the mass flow rate as a function of either temperature or pressure. As such, the control unit 40 receives the measurement signal, determines whether the refrigerant is at a desirable temperature or pressure level, and sends a fan control signal to the fan controller 35 based on such determination. If the refrigerant is unfavorably cold or pressurized on entering the condenser 15, the fan controller 37 will decrease the speed of the fan 35 by decreasing the power delivered to the fan motor 30 from the power supply 39, thereby warming the refrigerant. If the refrigerant is unfavorably warm or pressurized on entering the condenser 15, the fan controller 37 will increase the speed of the fan 35 by increasing the power delivered to the fan motor 30 from the power supply 39, thereby cooling the refrigerant. Lastly, if the refrigerant exhibits a favorable mass flow rate on entering the condenser 15, the fan controller 37 will maintain the existing speed of the fan 35. In another embodiment, the fan controller 37 is a switch for variably controlling the speed of the fan 35 between an "on" and an "off' position based on the fan control signal emitted from the control unit 40. The switch is continuously rendered in either an "on" or an "off' position in accordance with the mass flow rate of refrigerant measured by the sensor 45. Inasmuch, when the air temperature surrounding the refrigeration line 5 in the condenser 15 is unfavorably warm, the fan control system switches the fan 35 "on" to cool the refrigerant. Operatively, the fan controller 37 will render the fan 35 in an "on" position by closing the switch, thereby providing a direct path across line 44 for the delivery of power from the power supply 39 to the fan motor 30. In a similar manner, when the air temperature is unfavorably cool, especially in low ambient conditions, the fan control system switches the fan 35 "off' to warm the refrigerant, thereby guarding a refrigeration unit from adverse conditions such as supercooling of a condenser. Operatively, the fan controller 37 will render the fan 35 in an "off position by opening the switch, thereby cutting off the path across line 44 for the delivery of power from the power supply 39 to the fan motor 30. The preferred flow modulation unit includes the sensor 45 and the control unit 40 as described above, however, an alternative flow modulation unit includes an expansion device 50 operatively linked with the control unit 40 via line 43 for regulating the mass flow rate of refrigerant through the refrigeration line 5. The expansion device 50 is in operative engagement with the refrigerant line 5 and, in this embodiment, is positioned substantially adjacent to the evaporator 20 to control the flow of refrigerant entering the evaporator 20. The expansion device 50 includes a valve that biases the refrigeration line 5 in an open position or in a closed position based on a valve signal generated by the control unit 40 in response to a measurement signal from the sensor 45. Accordingly, the expansion device 50 modulates the mass flow rate of the refrigerant through the refrigeration line 5 and, ultimately, controls the size and growth rate of the slab 65 about the evaporator coil 22. In particular, while in an open position, the valve permits cooled refrigerant to flow from the condenser 15 to the evaporator 20, thereby permitting the slab 65 to grow to a sufficient size. While in a closed position, the valve stops the flow of refrigerant to the evaporator 20, thereby restricting the size of the slab 65. In another embodiment of the flow modulation unit, the valve of the expansion device 50 may be rendered in a partially closed position to further control the size and rate of growth of slab 65.

In operation, sensor 45 measures for the mass flow rate of refrigerant flowing into condenser 15 as a function of either temperature or pressure and emits a measurement signal. The control unit 40 receives the measurement signal, determines whether the refrigerant is at a desirable level, and sends a valve signal to the flow modulation unit based on such determination. If the refrigerant is unfavorably cold on entering the condenser 15, for example, the valve from the flow modulation unit will be rendered in a closed position or in a more closed position in accordance with the valve signal, thereby restricting the size of the slab 65. If the refrigerant is unfavorably warm on entering the condenser 15, the valve will be rendered in an open position or in a more open position, thereby permitting the slab 65 to grow to a sufficient size. Lastly, if the refrigerant exhibits a favorable mass flow rate on entering the condenser 15, valve will maintain its existing open or closed position. Although the present invention has been described in terms of the foregoing embodiment, such description has been for exemplary purposes only and, as will be apparent to those of ordinary skill in the art, many alternatives, equivalents, and variations of varying degrees will fall within the scope of the present invention. That scope, accordingly, is not to be limited in any respect by the foregoing description, rather, it is defined only by the claims that follow.

Claims

CLAIMS We claim:

1. An apparatus for cooling a cooling fluid contained in a cooling chamber, comprising: a refrigeration unit; and a fan control assembly operatively engaged with the refrigeration unit for controlling the flow of refrigerant through the refrigeration unit.

2. The apparatus according to claim 1 wherein the fan control assembly comprises: a sensor positioned along the refrigeration unit for measuring the flow rate of refrigerant and correspondingly transmitting a measurement signal; a control unit linked with the sensor for comparing the measurement signal with a desired measurement and correspondingly generating a fan control signal; and a fan controller linked with the control unit for controlling the flow of refrigerant through the refrigeration unit pursuant to the fan control signal.

3. The apparatus according to claim 1 wherein the refrigeration unit comprises: a refrigeration line through which refrigerant flows; a compressor for pumping refrigerant through the refrigeration line; a condenser including a fan for removing heat from the refrigeration line; and an evaporator for introducing the refrigeration line into a cooling fluid bath to freeze cooling fluid into a slab.

4. The apparatus according to claim 3 wherein the fan control assembly comprises: a sensor positioned along the refrigeration line for measuring flow rate of refrigerant and correspondingly transmitting a measurement signal; a control unit linked with the sensor for comparing the measurement signal with a desired measurement and correspondingly generating a fan control signal; and

a fan controller linked with the control unit for controlling speed of the fan pursuant to the fan control signal.

5. The apparatus according to claim 3 wherein the fan control assembly is in operative engagement with the refrigeration unit for controlling the flow of refrigerant through the refrigeration line.

6. The apparatus according to claim 4 wherein the fan controller comprises a transducer.

7. The apparatus according to claim 6 wherein the transducer is linked with the control unit and linked with the fan.

8. The apparatus according to claim 6 wherein the transducer variably controls speed of the fan pursuant to the fan control signal received from the control unit.

9. The apparatus according to claim 4 wherein the fan controller comprises a switch.

10. The apparatus according to claim 9 wherein the switch is linked with the control unit and linked with the fan.

11. The apparatus according to claim 9 wherein the switch is rendered in either an on or an off position pursuant to the fan control signal received from the control unit, thereby controlling speed of the fan.

12. The apparatus according to claim 9 wherein the switch is continuously rendered in either an on or an off position pursuant to the fan control signal received from the control unit, thereby controlling speed of the fan.

13. An apparatus for cooling a cooling fluid contained in a cooling chamber, comprising: a refrigeration unit; and a flow modulation unit in operative engagement with the refrigeration unit for providing flow control of refrigerant through the refrigeration unit.

14. The apparatus according to claim 13 wherein the flow modulation unit comprises: a sensor positioned along the refrigeration unit for measuring flow rate of refrigerant and correspondingly transmitting a measurement signal; a control unit linked with the sensor for comparing the measurement signal with a desired measurement and correspondingly generating a valve signal; and an expansion device linked with the control unit for controlling flow of refrigerant pursuant to the valve signal.

15. The apparatus according to claim 13 wherein the refrigeration unit comprises: a refrigeration line through which refrigerant flows; a compressor for pumping refrigerant through the refrigeration line; a condenser including a fan for removing heat from the refrigeration line; and an evaporator for introducing the refrigeration line into a cooling fluid bath to freeze cooling fluid into a slab.

16. The apparatus according to claim 15 wherein the expansion device comprises a valve in cooperative engagement with the refrigeration line for regulating flow of refrigerant pursuant to a valve signal.

17. The apparatus according to claim 16 wherein the valve is biased in a closed position and in an open position.

18. The apparatus according to claims 16 or 17 wherein the valve is rendered in a partially closed position.

19. The apparatus according to claim 15 wherein the expansion device is positioned substantially adjacent the evaporator.

20. The apparatus according to claim 15 wherein the refrigeration unit further comprises a growth control system for the slab that regulates size and growth rate of the slab and includes an array of probes, operationally linked with the compressor, for detecting size and growth rate of the slab and for correspondingly transmitting a probe signal to the compressor, whereby the compressor pumps refrigerant through the refrigeration line pursuant to the probe signal.

21. The apparatus according to claim 20 wherein the flow modulation unit is in cooperative engagement with the growth control system for the slab, thereby controlling slab growth and size.

22. A method for cooling cooling fluid contained in a refrigeration unit, comprising the steps of: linking a control assembly in operative engagement with the refrigeration unit, the control assembly including a sensor positioned along the refrigeration unit and a control unit linked with the sensor; measuring the flow rate of refrigerant with the sensor and correspondingly transmitting a measurement signal therefrom; and comparing the measurement signal to a desired measurement with the control unit and correspondingly generating a control signal therefrom.

23. The method according to claim 22 wherein the control assembly further comprises an active fan control assembly including a fan controller linked with the control unit.

24. The method according to claim 23 further comprising the steps of: providing a fan in operative engagement with the refrigeration unit; and controlling the speed of the fan with the fan controller pursuant to the control signal.

25. The method according to claim 24 wherein the active fan control assembly provides variable flow control of refrigerant as a function of controlling speed of the fan, and, thus, ultimately facilitates flow control of refrigerant through a refrigeration unit.

26. The method according to claims 22 wherein the control assembly further comprises a flow modulation unit including an expansion device linked with the control unit.

27. The method according to claim 26 further comprising the steps of: providing refrigerant in operative engagement with the refrigeration unit; and controlling flow of refrigerant with the expansion device pursuant to the control signal.

28. The method according to claim 27 wherein the flow modulation unit facilitates flow control of refrigerant across a refrigeration unit.

29. The method according to claim 24 further comprising the steps of: forming a slab of frozen cooling fluid within the cooling chamber by cooling the cooling fluid; and regulating the size and growth rate of the slab with a growth control system in operative engagement with the refrigeration unit

30. The method according to claim 29 further comprising the step of linking the fan control assembly in cooperative engagement with the growth control system for the slab, thereby controlling slab growth and size.

31. The method according to claim 26 further comprising the steps of: forming a slab of frozen cooling fluid within the cooling chamber by cooling the cooling fluid; and regulating the size and growth rate of the slab with a growth control system in operative engagement with the refrigeration unit 32. The method according to claims 31 further comprising the step of linking the flow modulation unit in cooperative engagement with the growth control system for the slab, thereby controlling slab growth and size.