JP2012007781A - Refrigerator/freezer and cooling device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a refrigerator/freezer including a binary refrigerating cycle in which power consumption can be reduced.SOLUTION: In a refrigerator/freezer 1 including a cooling compartment 3 refrigerating and preserving stored objects, a freezing compartment 4 freezing and preserving stored objects, a first compressor 11 operating a high temperature refrigerating cycle 10, a second compressor 21 operating a low temperature freezing cycle 20, an intermediate heat exchanger 31 performing heat exchange between a low temperature part of the high temperature refrigerating cycle 10 and a high temperature part of the low temperature freezing cycle 20, a first evaporator 14 arranged at the low temperature part of the high temperature refrigerating cycle 10 and the freezing compartment 3, and a second evaporator 24 arranged at the low temperature part of the low temperature refrigerating cycle 20 and cooling the freezing compartment 4, the first compressor 11 drive-controlled so as keep a compression rate at a first setting value, while the second compressor 21 is drive-controlled so as to keep a compression rate at a second setting value, the first setting value is changed in accordance with ambient temperature of the refrigerator/freezer, while the second setting temperature is made to the prescribed compression rate being not depend on the ambient temperature.

Description

  The present invention relates to a refrigerator-freezer and a cooling device provided with a dual refrigeration cycle.

  A conventional refrigerator-freezer is disclosed in Patent Document 1. This refrigerator-freezer has a high-temperature refrigeration cycle operated by a first compressor and a low-temperature refrigeration cycle operated by a second compressor, and has a dual refrigeration cycle. The dual refrigeration cycle is provided with an intermediate heat exchanger that performs heat exchange between the low temperature portion of the high temperature refrigeration cycle and the high temperature portion of the low temperature refrigeration cycle. A first evaporator is provided in the low temperature part of the high temperature refrigeration cycle, and a second evaporator is provided in the low temperature part of the low temperature refrigeration cycle.

  By driving the first compressor, the intermediate heat exchanger and the first evaporator in the low temperature part of the high temperature refrigeration cycle are maintained at a low temperature. The refrigerator compartment is cooled by the cold air exchanged with the first evaporator, and the refrigerator compartment is maintained at the set temperature. By driving the second compressor, the refrigerant in the low temperature refrigeration cycle dissipates heat in the intermediate heat exchanger and is condensed. The second evaporator in the low temperature part of the low temperature refrigeration cycle is maintained at a lower temperature than the intermediate heat exchanger. Thereby, the freezer compartment is cooled to a temperature lower than that of the refrigerator compartment by the cold air exchanged with the second evaporator, and the freezer compartment is maintained at the set temperature.

Japanese Patent Laying-Open No. 2009-300000 (pages 5 to 10 and FIG. 5) Japanese Patent Laying-Open No. 2005-106365 (pages 7 to 11, FIG. 1)

  According to the conventional refrigerator-freezer, in order to maintain the refrigerator compartment and the freezer compartment at the set temperature, the first compressor and the second compressor are driven when the indoor temperature of the refrigerator compartment or the freezer compartment rises above the preset temperature. At this time, when the first compressor or the second compressor is driven at the maximum capacity, the set temperature can be reached quickly.

  However, if the first compressor or the second compressor is always driven at the maximum capacity, the COP (Coefficient Of Performance) of the dual refrigeration cycle may be reduced. Therefore, there is a problem that the power consumption of the refrigerator / freezer increases.

  An object of this invention is to provide the refrigerator-freezer and cooling device provided with the dual freezing cycle which can reduce power consumption.

  In order to achieve the above object, the present invention provides a refrigerating room for refrigerated storage, a freezing room for freezing stored storage, a first compressor for operating a high-temperature refrigeration cycle, and a first operation for operating a low-temperature refrigeration cycle. Two compressors, a control unit that drives and controls the first compressor and the second compressor, an intermediate heat exchanger that performs heat exchange between a low temperature part of the high temperature refrigeration cycle and a high temperature part of the low temperature refrigeration cycle, A first evaporator disposed in a low temperature part of the high temperature refrigeration cycle for cooling the refrigerator compartment, and a second evaporator disposed in a low temperature part of the low temperature refrigeration cycle for cooling the freezer chamber. In the refrigerator, the first compressor is driven and controlled to maintain the compression ratio at the first set value, and the second compressor is driven and controlled to maintain the compression ratio at the second set value. And change according to the ambient temperature of the refrigerator In, and a second set value, characterized in that the predetermined compression ratio does not depend on the ambient temperature.

  According to this configuration, when the first compressor is driven, the high temperature refrigeration cycle is operated, and the refrigerator compartment is cooled by heat exchange with the first evaporator disposed in the low temperature portion of the high temperature refrigeration cycle. By driving the second compressor, the refrigerant in the low temperature refrigeration cycle dissipates heat in the intermediate heat exchanger and is condensed. The second evaporator in the low temperature part of the low temperature refrigeration cycle is maintained at a lower temperature than the intermediate heat exchanger, and the freezing room is cooled to a lower temperature than the refrigerator room by heat exchange with the second evaporator. The first compressor is controlled by the control unit to maintain the compression ratio at the first set value, and the first set value is changed according to the ambient temperature of the refrigerator-freezer. The second compressor is controlled by the control unit to maintain the compression ratio at the second set value, and the second set value is maintained at the predetermined compression ratio regardless of the ambient temperature of the refrigerator-freezer.

  Further, the present invention is characterized in that, in the refrigerator-freezer configured as described above, the first set value is increased as the ambient temperature increases.

  Further, the present invention provides a refrigerator-freezer configured as described above, wherein the refrigerator temperature detecting means for detecting the temperature of the refrigerator compartment, the ambient temperature detecting means for detecting the ambient temperature, and the first evaporator or the intermediate heat exchanger. First evaporating temperature detecting means for detecting the evaporating temperature, and the control based on detection results of the refrigerating room temperature detecting means, the ambient temperature detecting means and the first evaporating temperature detecting means, and a set temperature of the refrigerating room. The capacity of the first compressor is adjusted so that the evaporation temperature of the first evaporator is maintained at the first predetermined temperature value calculated by the unit.

  According to this configuration, the first predetermined temperature value is calculated by the control unit based on the detected temperature of the refrigerator compartment, the ambient temperature, the evaporation temperature of the intermediate heat exchanger or the first evaporator, and the set temperature of the refrigerator compartment. The evaporation temperature of the first evaporator is maintained at a first predetermined temperature value by adjusting the capacity of the first compressor. Thereby, the compression ratio of the first compressor is maintained at the first set value.

  Further, the present invention is a refrigerator-freezer having the above-described configuration, comprising: freezing room temperature detecting means for detecting the temperature of the freezing room; and second evaporating temperature detecting means for detecting the evaporation temperature of the second evaporator; In order to maintain the evaporation temperature of the second evaporator at the second predetermined temperature value calculated by the control unit based on the detection result of the temperature detection means and the second evaporation temperature detection means and the set temperature of the freezer compartment, It is characterized by adjusting the capacity of the second compressor.

  According to this configuration, the second predetermined temperature value is calculated by the control unit based on the detected temperature of the freezer, the evaporation temperature of the second evaporator, and the set temperature of the freezer. The evaporation temperature of the second evaporator is maintained at a second predetermined temperature value by adjusting the capacity of the second compressor. Thereby, the compression ratio of the second compressor is maintained at the second set value.

  According to the present invention, in the refrigerator-freezer configured as described above, the evaporating temperature of the first evaporator is maintained at a first predetermined temperature value, and the evaporating temperature of the second evaporator is maintained at a second predetermined temperature value. The capacities of the first compressor and the second compressor are adjusted such that the temperature of the freezer and the temperature of the freezer compartment become the respective set temperatures.

  According to this configuration, the evaporation temperature of the first evaporator is maintained at the first predetermined temperature value by adjusting the capacity of the first compressor, and the evaporation temperature of the second evaporator is adjusted by adjusting the capacity of the second compressor. 2 Driving to maintain a predetermined temperature value, the refrigerator compartment and the freezer compartment are each maintained at a set temperature.

  Moreover, the present invention is characterized in that, in the refrigerator-freezer configured as described above, the control unit has a function of converting the pressure and temperature of the refrigerant in the high-temperature refrigeration cycle and the low-temperature refrigeration cycle. According to this configuration, the pressure of the refrigerant in the high temperature refrigeration cycle and the low temperature refrigeration cycle is converted by the control unit based on the temperature of the refrigerant. Thereby, the temperature of the refrigerant is detected, the compression ratio of the first compressor and the second compressor is calculated, and the compression ratio of the first compressor and the second compressor is maintained at the first set value and the second set value. Is done.

  Moreover, the present invention is characterized in that the capacity of the first and second compressors is adjusted by varying the number of revolutions in the refrigerator-freezer configured as described above.

  Further, the present invention is characterized in that the first decompressor provided in the high-temperature refrigeration cycle and the second decompressor provided in the low-temperature refrigeration cycle are formed by capillary tubes in the refrigerator-freezer configured as described above. According to this configuration, the refrigerant in the high-temperature refrigeration cycle that is circulated by driving the first compressor condenses in the high-temperature portion, expands in the first decompression device including the capillary tube, and evaporates in the low-temperature portion. The refrigerant of the low-temperature refrigeration cycle that is circulated by driving the second compressor condenses in the high-temperature part, expands in the second decompression device composed of a capillary tube, and evaporates in the low-temperature part.

  According to the present invention, in the refrigerator-freezer configured as described above, at the start of driving the first and second compressors, the first compressor is driven so that the evaporation temperature of the intermediate heat exchanger or the first evaporator is higher than a predetermined temperature. After the decrease, the second compressor is driven.

  The present invention also provides first and second spaces set at different temperatures, a first compressor that operates a high-temperature refrigeration cycle, a second compressor that operates a low-temperature refrigeration cycle, a first compressor, and a second compressor. A control unit that drives and controls the compressor, an intermediate heat exchanger that performs heat exchange between a low temperature part of the high temperature refrigeration cycle and a high temperature part of the low temperature refrigeration cycle, and a low temperature part of the high temperature refrigeration cycle In a cooling device including a first evaporator that cools a first space and a second evaporator that is disposed in a low-temperature portion of the low-temperature refrigeration cycle and cools a second space, the first compressor has a first compression ratio. The second compressor is controlled to be maintained at the first set value and the second compressor is controlled to maintain the compression ratio at the second set value, and the first set value is changed according to the ambient temperature of the cooling device. The second set value is a predetermined value that does not depend on the ambient temperature. It is characterized in that the contraction ratio.

  According to the present invention, the first compressor of the high-temperature refrigeration cycle that cools the refrigerator compartment is controlled while maintaining the compression ratio at the first set value, and the second compressor of the low-temperature refrigeration cycle that cools the freezer compartment is the compression ratio. Is controlled at the second set value. Then, the first set value is changed according to the ambient temperature, and the second set value is maintained at a predetermined compression ratio that does not depend on the ambient temperature. As a result, the binary refrigeration cycle can be easily controlled with optimum efficiency. Therefore, the power consumption of the refrigerator-freezer can be reduced.

Schematic block diagram of the refrigerator-freezer of 1st Embodiment of this invention. The figure which shows the refrigerating cycle of the freezer refrigerator of 1st Embodiment of this invention. PH diagram of the refrigerator-freezer according to the first embodiment of the present invention. The figure which shows the relationship between the compression ratio of the 1st compressor from which the COP of the refrigerator-freezer of 1st Embodiment of this invention becomes the maximum value, and the ambient temperature of a refrigerator-freezer. The figure which shows the relationship between the compression ratio of the 2nd compressor from which the COP of the refrigerator-freezer of 1st Embodiment of this invention becomes the maximum, and the ambient temperature of a refrigerator-freezer. Diagram showing the relationship between adiabatic compression efficiency and compression ratio of positive displacement compressors The schematic block diagram of the refrigerator-freezer of 2nd Embodiment of this invention. The figure which shows the refrigerating cycle of the freezer refrigerator of 3rd Embodiment of this invention.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram of the refrigerator-freezer of the first embodiment. The refrigerator-freezer 1 includes a heat insulating box 2 filled with a foam heat insulating material, and a refrigerating room 3 for refrigerated storage of stored items is disposed above the heat insulating box 2. In the lower part of the heat insulation box 2, a freezer compartment 4 for storing stored items in a frozen state is disposed, and the refrigerator compartment 3 and the freezer compartment 4 are partitioned by a heat insulation wall 2a. The front surfaces of the refrigerator compartment 3 and the freezer compartment 4 are opened and closed by heat insulating doors 3a and 4a, respectively.

  A machine room 5 is provided behind the freezer room 4. In the machine room 5, first and second compressors 11 and 21 for operating a high-temperature refrigeration cycle 10 and a low-temperature refrigeration cycle 20 (see FIG. 2), which will be described in detail later, are arranged. A first evaporator 14 connected to the first compressor 11 is disposed on the back of the refrigerator compartment 3, and a refrigerator refrigerator 15 is disposed above the first evaporator 14. A second evaporator 24 connected to the second compressor 21 is disposed on the back surface of the freezer compartment 4, and a freezer compartment blower 25 is disposed above the second evaporator 24.

  A control unit 7 that controls each unit of the refrigerator 1 is provided in the machine room 5. The control unit 7 is connected to the first compressor 11, the second compressor 12, the refrigerator compartment fan 15, and the freezer compartment fan 25. The first compressor 11 and the second compressor 12 are controlled by a compressor control unit (not shown) provided in the control unit 7. The refrigerator compartment blower 15 and the freezer compartment blower 25 are controlled by a blower control unit (not shown) provided in the control unit 7.

  In addition, an ambient temperature sensor 9, a refrigerator temperature sensor 19, a freezer temperature sensor 29, and a first evaporation temperature sensor 18 are connected to the controller 7. The ambient temperature sensor 9 (ambient temperature detection means) is provided on the upper surface of the heat insulating box 2 and detects the outside air temperature that is the ambient temperature of the refrigerator-freezer 1. The refrigerator compartment temperature sensor 19 (refrigerator compartment temperature detection means) detects the room temperature of the refrigerator compartment 3. The freezer compartment temperature sensor 29 (freezer compartment temperature detection means) detects the room temperature of the freezer compartment 4.

  The first evaporation temperature sensor 18 (first evaporation temperature detection means) detects the evaporation temperature of the first evaporator 14. Thereby, the evaporation temperature of the high temperature refrigeration cycle 10 is detected. In addition, an intermediate heat exchanger 31 described later is provided in the heat insulating box 2. Instead of the first evaporation temperature sensor 18, a first evaporation temperature sensor 18 ′ that detects the evaporation temperature of the intermediate heat exchanger 31 may be provided to detect the evaporation temperature of the high-temperature refrigeration cycle 10.

  Cold air cooled by exchanging heat with the first evaporator 14 is discharged to the refrigerator compartment 3 by the refrigerator refrigerator 15. The cold air flows through the refrigerator compartment 3 and returns to the first evaporator 14 from the lower portion of the refrigerator compartment 3. Thereby, the refrigerator compartment 3 is cooled. The cold air cooled by exchanging heat with the second evaporator 24 is discharged to the freezer compartment 4 by the freezer blower 25. The cold air discharged into the freezer compartment 4 flows through the freezer compartment 4 and returns to the second evaporator 24. Thereby, the freezer compartment 4 is cooled.

  FIG. 2 shows the refrigeration cycle of the refrigerator 1. The refrigeration cycle 30 of the refrigerator / freezer 1 is a cascade type dual refrigeration cycle in which a high-temperature refrigeration cycle 10 and a low-temperature refrigeration cycle 20 are connected by an intermediate heat exchanger 31. The high-temperature refrigeration cycle 10 operated by the first compressor 11 has a first radiator 12, a first decompressor 13, and a first evaporator 14 connected by a refrigerant pipe 16. A first refrigerant such as isobutane flows in the refrigerant pipe 16 in the direction of the arrow S1. That is, the first refrigerant circulates through the first compressor 11, the first radiator 12, the first decompressor 13, the first evaporator 14, and the first compressor 11 in this order. The first decompression device 13 is formed by a capillary tube.

  The low-temperature refrigeration cycle 20 operated by the second compressor 21 has a second radiator 22, a second decompressor 23, and a second evaporator 24 connected by a refrigerant pipe 26. A second refrigerant such as isobutane flows in the refrigerant pipe 26 in the direction of the arrow S2. That is, the second refrigerant circulates through the second compressor 21, the second radiator 22, the second decompressor 23, the second evaporator 24, and the second compressor 21 in this order. The second decompression device 23 is formed by a capillary tube.

  The intermediate heat exchanger 31 is formed so that the heat exchanging portion 31a provided in the high-temperature refrigeration cycle 10 and the heat exchanging portion 31b provided in the low-temperature refrigeration cycle 20 are adjacent to each other and can exchange heat with each other through wall surfaces. The heat exchanging part 31 a is arranged downstream of the first evaporator 14, and the heat exchanging part 31 b is arranged downstream of the second radiator 22.

  In the refrigerator-freezer 1 having the above configuration, the first and second refrigerants flow through the refrigerant pipes 16 and 26 by driving the first and second compressors 11 and 21, respectively. The first and second compressors 11 and 21 compress the first and second refrigerants to high temperature and high pressure, and the first and second decompression devices 13 and 23 decompress and expand the first and second refrigerants at low temperature and low pressure. To.

  Accordingly, the high temperature portion of the high temperature refrigeration cycle 10 is obtained until the first refrigerant flows out of the first compressor 11 and flows into the first decompression device 13. The period until the second refrigerant flows out of the second compressor 21 and flows into the second decompression device 23 becomes the high temperature portion of the low temperature refrigeration cycle 20. In addition, the first refrigerant becomes a low temperature portion of the high temperature refrigeration cycle 10 until it flows out of the first decompression device 13 and flows into the first compressor 11. The period until the second refrigerant flows out of the second decompression device 23 and flows into the second compressor 21 becomes a low temperature part of the low temperature refrigeration cycle 20.

  The high-temperature and high-pressure first refrigerant compressed by the first compressor 11 is deprived of heat by the first radiator 12 and condensed. The first refrigerant liquefied by the first radiator 12 flows into the first decompressor 13. The first refrigerant is decompressed and expanded by the first decompression device 13, and becomes a low-temperature wet steam having a low dryness.

  The first refrigerant that has become low-temperature wet steam flows into the first evaporator 14, takes heat from the cold air in the refrigerator compartment 3, evaporates, and becomes wet steam with high dryness. The first refrigerant in the wet vapor state flowing out from the first evaporator 14 flows into the intermediate heat exchanger 31 and evaporates while taking heat from the second refrigerant in the high temperature part of the low temperature refrigeration cycle to become superheated vapor. The first refrigerant that has become superheated steam returns to the first compressor 11. Thereby, a 1st refrigerant | coolant circulates and the high temperature freezing cycle 10 is drive | operated.

  The high-temperature and high-pressure second refrigerant compressed by the second compressor 21 is deprived of the ambient air by the second radiator 22. The second refrigerant lowered in temperature by the second radiator 22 flows into the intermediate heat exchanger 31, and is deprived of heat by the first refrigerant in the low temperature part of the high temperature refrigeration cycle 10, and condensed. The liquefied second refrigerant flows into the second decompression device 23. The second refrigerant is decompressed and expanded by the second decompression device 23, and becomes low-temperature wet steam. The second refrigerant that has become low-temperature wet steam flows into the second evaporator 24, takes heat from the cold air in the freezer compartment 4, evaporates, and returns to the second compressor 21. Thus, the second refrigerant 21 is circulated by driving the second compressor 21 and the low temperature refrigeration cycle 20 is operated.

  FIG. 3 shows a pressure-enthalpy diagram (PH diagram) of the refrigeration cycle 30. The vertical axis represents pressure, and the horizontal axis represents enthalpy. Further, in the figure, each point A, B, C, D, E, a, b, b ', c, d corresponds to each point of the refrigeration cycle 30 shown in FIG.

  In the case of the high-temperature refrigeration cycle 10 (A-B-C-D-E-A), A-B represents a process in the first compressor 11. B-C represents a process in the first radiator 12. CD represents the process in the first pressure reducing device 13. DE represents the process in the first evaporator 14. E-A represents a process in the heat exchanging portion 31 a of the intermediate heat exchanger 31.

  The same applies to the low-temperature refrigeration cycle 20 (ab-b'-cda), where ab represents the process in the second compressor 21. b-b ′ represents the process in the second radiator 22. b′-c represents a process in the heat exchange part 31 b of the intermediate heat exchanger 31. cd represents the process in the second pressure reducing device 23. da represents a process in the second evaporator 24.

  Since the same refrigerant (for example, isobutane) is sealed in the high-temperature refrigeration cycle 10 and the low-temperature refrigeration cycle 20, the temperature relationship and pressure relationship of the high-temperature refrigeration cycle 10 and the low-temperature refrigeration cycle 20 are easily understood on the PH diagram. ing. For example, the pressure PA at the point A of the high temperature refrigeration cycle 10 is slightly lower than the pressure Pb at the point b of the low temperature refrigeration cycle 20. This is because the high temperature refrigeration cycle 10 takes heat away from the low temperature refrigeration cycle 20.

  As shown in the figure, the compression ratio of the first compressor 11 of the high-temperature refrigeration cycle 10 is the ratio (PB / PA) between the pressure PA at point A and the pressure PB at point B. The compression ratio of the second compressor 21 of the low-temperature refrigeration cycle 20 is the ratio (Pb / Pa) between the pressure Pa at the point a and the pressure Pb at the point b.

  The first compressor 11 and the second compressor 21 are inverter-controlled, and the capacity can be adjusted by controlling the rotation speed. In the present embodiment, the capacities of the first compressor 11 and the second compressor 21 are adjusted by a compressor control unit (not shown) of the control unit 7. Then, the compression ratios of the first compressor 11 and the second compressor 21 are controlled so as to be maintained at the first set value and the second set value, respectively.

  In FIG. 4, for example, the set temperature of the refrigerator compartment 3 is 4 ° C., the set temperature of the freezer compartment 4 is −18 ° C., the evaporation temperature of the first evaporator 14 is −2 ° C., and the first and second refrigerants are isobutane. The relationship between the compression ratio of the first compressor 11 at which the COP becomes the maximum value and the ambient temperature of the refrigerator-freezer 1 is shown by the optimization calculation at that time. FIG. 5 shows the relationship between the compression ratio of the second compressor 21 and the ambient temperature of the refrigerator-freezer 1 at which the COP at this time becomes the maximum value.

  According to these figures, the first compressor 11 has a large change in the optimum compression ratio with respect to a change in the ambient temperature, and increases as the ambient temperature increases. Further, the optimal compression ratio of the second compressor 21 slightly changes with changes in ambient temperature, but is substantially constant.

  For this reason, the first compressor 11 is driven and controlled so that the compression ratio is maintained at the first set value that is an optimum value determined according to the ambient temperature. When the ambient temperature detected by the ambient temperature sensor 9 changes, the first set value is changed. The second compressor 21 is driven and controlled so that the compression ratio is maintained at a second set value of a predetermined value (for example, 2.5) that does not depend on the ambient temperature. Thereby, the refrigerator-freezer 1 can implement | achieve the highly efficient driving | operation with a high COP.

  Note that the optimal compression ratio of the first compressor 11 and the second compressor 21 changes even at the same ambient temperature according to the set temperature of the refrigerator compartment 3 and the freezer compartment 4. For this reason, when the set temperature of the refrigerator compartment 3 and the freezer compartment 4 is determined by the user, the corresponding evaporation temperature of the first evaporator 14 is set. Then, the optimum first set value and second set value under these conditions are set. At this time, the first set value is changed according to the ambient temperature, and the second set value is set to a predetermined compression ratio that does not depend on the ambient temperature.

  For example, when the ambient temperature is 30 ° C., the refrigerator temperature is 4 ° C., the freezer temperature is −18 ° C., and the first and second refrigerants are isobutane, the compression ratio of the single refrigeration cycle is about 8 is there. On the other hand, as shown in FIGS. 4 and 5, the compression ratio of the first compressor 11 and the second compressor 21 is 4 or less.

  Fig. 6 shows the relationship between adiabatic compression efficiency and compression ratio of positive displacement compressors according to ASHRAE (American Society of Heating, Refrigerating and Air-Conditioning Engineers) "Guide and Data Book" (1961, p498). Show. The vertical axis represents adiabatic compression efficiency, and the horizontal axis represents the compression ratio. Note that most of the compressors currently used in ordinary refrigerator-freezers are of the positive displacement type. Although the refrigerant is experimental data of R12 and R22, it can be said that other refrigerants have the same tendency. According to the figure, the smaller the compression ratio of the compressor, the higher the adiabatic compression efficiency of the compressor. Therefore, in this embodiment, since the compression ratios of the high temperature refrigeration cycle 10 and the low temperature refrigeration cycle 20 are both small, the first and second compressors 11 and 21 can be operated with higher efficiency.

  The compression ratio of the first and second compressors 11 and 21 may be monitored by a pressure sensor or the like and maintained at the first set value and the second set value. However, the condensation temperatures of the high temperature refrigeration cycle 10 and the low temperature refrigeration cycle 20 are below the critical point of the refrigerant. For this reason, the condensation pressure and evaporation pressure which are saturation pressures are uniquely determined by the condensation temperature and the evaporation temperature. For example, Table 1 shows the corresponding values of the temperature and saturation pressure of isobutane that can be used as the first and second refrigerants.

  Therefore, the evaporation pressure of the high-temperature refrigeration cycle 10 can be derived by calculation based on the evaporation temperature of the high-temperature refrigeration cycle 10 detected by the first evaporation temperature sensor 18. In addition, the condensing temperature and condensing pressure of the high-temperature refrigeration cycle 10 are determined based on the ambient temperature and characteristic data acquired in advance such as the first radiator 12, the first pressure reducing device 13, and the first compressor 11.

  Further, since the detected temperature of the first evaporation temperature sensor 18 is substantially equal to the evaporation temperature of the intermediate heat exchanger 31, the condensation temperature of the low temperature refrigeration cycle 20 can be obtained. Thereby, the condensation pressure of the low-temperature refrigeration cycle 20 is determined. In addition, the evaporation temperature and evaporation pressure of the low-temperature refrigeration cycle 20 are determined based on the characteristic data of the second decompression device 23, the second compressor 21, and the like.

  For this reason, by monitoring the evaporation temperature of the first evaporator 14, the compression ratios of the first and second compressors 11 and 21 can be maintained at the first and second set values, respectively. That is, a first predetermined value that is a target value for controlling the first evaporator 14 based on the evaporation temperature of the first evaporator 14, the detected temperature of the refrigerator 2, the ambient temperature of the refrigerator 1, and the set temperature of the refrigerator 2. The temperature value is calculated by the control unit 7. Then, the outputs of the first compressor 11 and the second compressor 21 are controlled so that the evaporation temperature of the first evaporator 14 is maintained at the first predetermined temperature value.

  At this time, as the first and second pressure reducing devices 13 and 23, expansion valves having variable throttling amounts or the like may be used. However, if a capillary tube is used, the flow rate and pressure characteristics become constant. Therefore, the condensation pressure of the high-temperature refrigeration cycle 10 and the evaporation pressure of the low-temperature refrigeration cycle 20 can be easily obtained by using the flow rate pressure characteristic inherent to the capillary tube.

  In addition, when the first compressor 11 and the second compressor 21 are started to be driven, the first compressor 11 is started, and the temperature detected by the first evaporation temperature sensor 18 is lower than a predetermined temperature (for example, 5 ° C.). Later, the second compressor 21 is activated. Thereby, the rapid temperature rise of the suction | inhalation refrigerant | coolant of the 1st compressor 11 by the heat radiation of the low-temperature refrigerating cycle 20 can be prevented, and the 1st compressor 11 can be protected.

  According to this embodiment, the first compressor 11 of the high-temperature refrigeration cycle 10 that cools the refrigerator compartment 3 is controlled while maintaining the compression ratio at the first set value, and the first compressor 11 of the low-temperature refrigeration cycle 20 that cools the freezer compartment 4 is controlled. The two compressors 21 are controlled while maintaining the compression ratio at the second set value. Then, the first set value is changed according to the ambient temperature of the refrigerator-freezer 1, and the second set value is maintained at a predetermined compression ratio that does not depend on the ambient temperature of the refrigerator-freezer 1.

  At this time, since the binary refrigeration cycle is controlled with an optimal compression ratio, the power consumption of the refrigerator-freezer 1 can be reduced. Moreover, since the 2nd setting value will be maintained constant if the preset temperature of the refrigerator compartment 3 and the freezer compartment 4 is constant, the 2nd compressor 21 can be controlled easily.

  In addition, since the first set value is increased as the ambient temperature increases, the two-stage refrigeration cycle can be easily controlled with optimum efficiency.

  Further, the detection results of the refrigerator compartment temperature sensor 19 (refrigerator compartment temperature detection means), the ambient temperature sensor 9 (ambient temperature detector means), and the first evaporation temperature sensor 18 (first evaporation temperature detector means) and the set temperature of the refrigerator compartment 2 Since the capacity of the first compressor 11 is adjusted so as to maintain the evaporation temperature of the first evaporator 14 at the first predetermined temperature value calculated based on the above, the compression ratio of the first compressor 11 can be easily set to the first One set value can be maintained. Moreover, since a pressure sensor etc. are not required, the cost of the refrigerator-freezer 1 can be reduced.

  Moreover, since the control part 7 has the function to convert the pressure and temperature of the refrigerant | coolant of the high temperature refrigeration cycle 10 and the low temperature refrigeration cycle 20, it derives | leads-out the evaporation temperature of the 1st evaporator 14 corresponding to a 1st setting value. Can do.

  Further, the capacities of the first compressor 11 and the second compressor 21 can be easily adjusted by changing the rotation speed.

  In addition, since the first decompression device 13 of the high-temperature refrigeration cycle 10 and the second decompression device 23 of the low-temperature refrigeration cycle are formed by capillary tubes, the high-temperature refrigeration cycle 10 can be easily used by utilizing the flow rate and pressure characteristics inherent to the capillary tubes. And the evaporation pressure of the low-temperature refrigeration cycle 20 can be acquired.

  In addition, when the first compressor 11 and the second compressor 21 are started to be driven, the first compressor 11 is started, and after the temperature detected by the first evaporation temperature sensor 18 falls below a predetermined temperature, the second compressor 21 is activated, it is possible to prevent a sudden rise in the temperature of the refrigerant sucked by the first compressor 11 due to the heat radiation of the low-temperature refrigeration cycle 20, and to protect the first compressor 11.

  Next, FIG. 7 has shown the schematic block diagram of the refrigerator-freezer of 2nd Embodiment. For convenience of explanation, the same reference numerals are given to the same parts as those in the first embodiment shown in FIGS. In the present embodiment, a second evaporator temperature sensor 28 is provided in addition to the first embodiment. Other parts are the same as those in the first embodiment.

  The second evaporation temperature sensor 28 (second evaporation temperature detection means) is connected to the control unit 7 and detects the evaporation temperature of the low temperature refrigeration cycle 20 by detecting the temperature of the second evaporator 24. For this reason, the compression ratio of the second compressor 21 can be maintained at the second set value by monitoring the evaporation temperature of the second evaporator 24.

  That is, based on the evaporation temperature of the second evaporator 24, the detected temperature of the freezer compartment 4, and the set temperature of the freezer compartment 4, a second predetermined temperature value that is a target value for controlling the second evaporator 24 is set by the control unit 7. Calculated. Then, the capacity of the second compressor 21 is adjusted so that the evaporation temperature of the second evaporator 24 is maintained at the second predetermined temperature value.

  The evaporation temperature of the second evaporator 24 is set to, for example, 3 ° C. lower than the set temperature of the freezer compartment 4. Thus, when entering a stable control operation state, the temperature difference between the room temperature of the freezer compartment 4 and the evaporation temperature of the second evaporator 24 is controlled to be 3 ° C. For this reason, the energy loss (loss of effective energy) by the heat exchange in the 2nd evaporator 24 by this temperature difference becoming large can be suppressed.

  According to this embodiment, the same effect as that of the first embodiment can be obtained. Furthermore, the second predetermined temperature calculated based on the detection results of the freezer temperature sensor 29 (freezer temperature detection means) and the second evaporation temperature sensor 28 (second evaporation temperature detection means) and the set temperature of the freezer compartment 4. Since the capacity of the second compressor 21 is adjusted so that the evaporation temperature of the second evaporator 24 is maintained at a value, energy loss due to heat exchange in the second evaporator 24 can be suppressed.

  Further, the evaporation temperature of the first evaporator 14 is maintained at the first predetermined temperature value, the evaporation temperature of the second evaporator 24 is maintained at the second predetermined temperature value, and the temperatures of the refrigerator compartment 2 and the freezer compartment 4 are maintained. Since the capacities of the first compressor 11 and the second compressor 21 are adjusted so that the respective set temperatures become the respective set temperatures, the compression ratios of the first and second compressors 11 and 21 can be easily set to the first and second compressors, respectively. The set value can be maintained.

  Further, since the control unit 7 has a function of converting the pressure and temperature of the refrigerant in the high temperature refrigeration cycle 10 and the low temperature refrigeration cycle 20, the evaporation temperature of the second evaporator 24 corresponding to the second set value is derived by calculation. Can do.

  Next, FIG. 8 shows the refrigeration cycle of the refrigerator-freezer of the third embodiment. For convenience of explanation, the same reference numerals are given to the same parts as those in the first embodiment shown in FIGS. The refrigeration cycle 40 of the present embodiment is provided with a first internal heat exchanger 34, a second internal heat exchanger 32, and a third internal heat exchanger 33 compared to the first embodiment. Further, the first receiver 17 is provided in the heat exchanging portion 31 a on the high temperature refrigeration cycle 10 side of the intermediate heat exchanger 31, and the second receiver 27 is provided downstream of the second evaporator 24. Other parts are the same as those in the first embodiment.

  The heat exchange part 31a on the high temperature refrigeration cycle 10 side of the intermediate heat exchanger 31 has heat exchange parts 31c and 31d connected in series, and the first receiver 17 is arranged between the heat exchange parts 31c and 31d. The first receiver 17 and the second receiver 27 separate the gas and liquid, store the liquid refrigerant, and discharge the gas refrigerant. Thereby, the inflow of the liquid refrigerant to the first compressor 11 and the second compressor 21 is prevented.

  The first internal heat exchanger 34 adjoins the heat exchange part 34a arranged at the rear stage of the first radiator 12 and the heat exchange part 34b arranged at the rear stage of the intermediate heat exchanger 31, and heats them through the wall surfaces. Formed interchangeably. The first refrigerant before flowing into the first evaporator 14 flows through the heat exchanging part 34a, and the first refrigerant after flowing out of the intermediate heat exchanger 31 flows through the heat exchanging part 34b. Thereby, the enthalpy of the 1st refrigerant | coolant which flows in into the 1st evaporator 14 can be reduced, and the cooling capability of a 1st refrigerant | coolant can be improved.

  The second internal heat exchanger 32 is formed so that the heat exchanging part 32a provided in the high-temperature refrigeration cycle 10 and the heat exchanging part 32b provided in the low-temperature refrigeration cycle 20 are adjacent to each other and can exchange heat via wall surfaces. The heat exchanging part 32 a is arranged at the rear stage of the first internal heat exchanger 34, and the first refrigerant before flowing into the first evaporator 14 flows therethrough. The heat exchanging part 32b is arranged downstream of the second evaporator 24, and the second refrigerant after flowing out of the second evaporator 24 flows therethrough. Thereby, the enthalpy of the 1st refrigerant | coolant which flows in into the 1st evaporator 14 can be reduced more.

  The third internal heat exchanger 33 adjoins the heat exchange part 33a arranged in the subsequent stage of the intermediate heat exchanger 31 and the heat exchange part 33b arranged in the subsequent stage of the second evaporator 24, and heats them through the wall surfaces. Formed interchangeably. The second refrigerant before flowing into the second evaporator 24 flows through the heat exchange unit 33a, and the second refrigerant after flowing out of the second evaporator 24 flows through the heat exchange unit 33b. Thereby, the enthalpy of the 2nd refrigerant | coolant which flows in into the 2nd evaporator 24 can be reduced, and the cooling capacity of a 2nd refrigerant | coolant can be improved.

  According to this embodiment, the same effect as that of the first embodiment can be obtained. Furthermore, since the first, second, and third internal heat exchangers 34, 32, and 33 are provided, the dual refrigeration cycle can be operated and controlled with higher efficiency.

  As described above, the refrigerator-freezer 1 and the control method thereof according to the present invention enable the dual refrigerator cycle to be mounted on the refrigerator-freezer 1, and can control the temperature of the refrigerator compartment 3 and the refrigerator compartment 4 to the set temperature. In addition, the capacity control of the two first and second compressors 11 and 21 according to the ambient temperature of the refrigerator-freezer 1 and the set temperature of the refrigerator-freezer 1 supports the change in the heat load due to the ambient temperature of the refrigerator-freezer 1. it can. And the compression ratio of the 1st compressor 11 of the high temperature refrigeration cycle 10 and the 2nd compressor 21 of the low temperature refrigeration cycle 20 is maintained at each optimal value, and the refrigerator-freezer 1 more excellent in energy saving can be provided.

  Although the refrigerator-freezer 1 has been described in the first to third embodiments, the present invention can be applied to any cooling device having different temperature setting spaces.

  According to this invention, it can utilize for the refrigerator-freezer provided with the binary refrigeration cycle, and a cooling device.

DESCRIPTION OF SYMBOLS 1 Freezer refrigerator 2 Cold room 3 Vegetable room 4 Freezer room 5 Machine room 7 Control part 9 Ambient temperature sensor 10 High temperature freezing cycle 11 1st compressor 12 1st heat radiator 13 1st pressure reduction device 14 1st evaporator 15 Cold room fan 16, 26 Refrigerant pipe 18 First evaporating temperature sensor 19 Cold room temperature sensor 20 Low temperature refrigeration cycle 21 Second compressor 22 Second radiator 23, 43b Second decompressor 24, 44b Second evaporator 25 Freezer compartment fan 28 First 2 Evaporation temperature sensor 29 Freezer temperature sensor 30, 40 Refrigeration cycle 31 Intermediate heat exchanger 32 Second internal heat exchanger 33 Third internal heat exchanger 34 First internal heat exchanger

Claims (10)

  A refrigeration room for refrigerated storage, a freezer room for freezing storage, a first compressor for operating a high-temperature refrigeration cycle, a second compressor for operating a low-temperature refrigeration cycle, a first compressor, and a first compressor 2 A control unit for driving and controlling the compressor, an intermediate heat exchanger for exchanging heat between a low temperature part of the high temperature refrigeration cycle and a high temperature part of the low temperature refrigeration cycle, and a low temperature part of the high temperature refrigeration cycle A refrigerator having a first evaporator for cooling the refrigerator compartment and a second evaporator arranged in a low temperature part of the low temperature refrigeration cycle for cooling the refrigerator compartment, wherein the first compressor has a compression ratio. Drive control is performed to maintain the first set value and the second compressor is drive controlled to maintain the compression ratio at the second set value, and the first set value is changed according to the ambient temperature of the refrigerator-freezer. In addition, the second set value depends on the ambient temperature. Refrigerator, characterized in that the predetermined compression ratio does not.   The refrigerator-freezer according to claim 1, wherein the first set value is increased as the ambient temperature increases.   A refrigerator temperature detecting means for detecting the temperature of the refrigerator compartment, an ambient temperature detecting means for detecting the ambient temperature, and a first evaporation temperature detecting means for detecting the evaporation temperature of the first evaporator or the intermediate heat exchanger. And a first predetermined temperature value calculated by the control unit based on detection results of the refrigerator compartment temperature detector, the ambient temperature detector and the first evaporating temperature detector and the set temperature of the refrigerator compartment. The refrigerator-freezer according to claim 1 or 2, wherein the capacity of the first compressor is adjusted so as to maintain the evaporation temperature of one evaporator.   The freezer compartment temperature detecting means for detecting the temperature of the freezer compartment, and the second evaporation temperature detecting means for detecting the evaporation temperature of the second evaporator, are detected by the freezer compartment temperature detecting means and the second evaporation temperature detecting means. The capability of the second compressor is adjusted so as to maintain the evaporation temperature of the second evaporator at the second predetermined temperature value calculated by the control unit based on the result and the set temperature of the freezer compartment. The refrigerator-freezer of Claim 1 or Claim 2.   The evaporation temperature of the first evaporator is maintained at the first predetermined temperature value, the evaporation temperature of the second evaporator is maintained at the second predetermined temperature value, and the temperature of the refrigerator compartment and the temperature of the freezer compartment are respectively set. The refrigerator-freezer according to claim 1 or 2, wherein the capacities of the first compressor and the second compressor are adjusted so that the temperature is reached.   6. The refrigerator-freezer according to claim 3, wherein the control unit has a function of converting a pressure and a temperature of a refrigerant in the high-temperature refrigeration cycle and the low-temperature refrigeration cycle.   The capacity of the first compressor and the second compressor is adjusted by changing the number of rotations, and the refrigerator-freezer according to any one of claims 3 to 6.   The refrigeration according to any one of claims 3 to 7, wherein the first decompression device provided in the high-temperature refrigeration cycle and the second decompression device provided in the low-temperature refrigeration cycle are formed by capillary tubes. refrigerator.   At the start of driving the first and second compressors, the first compressor was driven and the second compressor was driven after the evaporation temperature of the intermediate heat exchanger or the first evaporator was lowered below a predetermined temperature. The refrigerator-freezer in any one of Claims 1-8 characterized by the above-mentioned.   Driving control of the first and second spaces set at different temperatures, the first compressor that operates the high-temperature refrigeration cycle, the second compressor that operates the low-temperature refrigeration cycle, and the first compressor and the second compressor Cooling the first space by being arranged in the control unit, the intermediate heat exchanger for exchanging heat between the low temperature part of the high temperature refrigeration cycle and the high temperature part of the low temperature refrigeration cycle, and the low temperature part of the high temperature refrigeration cycle The first compressor maintains a compression ratio at a first set value in a cooling device including a first evaporator that performs cooling and a second evaporator that is disposed in a low-temperature portion of the low-temperature refrigeration cycle and cools the second space. And the second compressor is controlled to maintain the compression ratio at the second set value, the first set value is changed according to the ambient temperature of the cooling device, and the second set value is set. With a predetermined compression ratio independent of the ambient temperature. Cooling apparatus according to claim.

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