The present invention relates to a refrigerating unit and a refrigerator equipped with the refrigerating unit.
In recent years, a refrigerating unit to provide cooling for a plurality of compartments, each provided with an evaporator, and a refrigerator equipped with the refrigerating unit have been disclosed.
A prior art refrigerating unit of this kind is disclosed in the Japanese Patent Application Unexamined Publication No. S58-219366 of 1984.
Next, a description is given to the aforementioned prior art refrigerating unit with reference to drawings.
FIG. 9 is a block diagram of a cooling system of the prior art refrigerating unit. In FIG. 9, a refrigerant compressed in a compressor 1 is condensed by dissipating heats in condenser 2 and then fed to refrigerant branching unit 3.
The branched refrigerant is partially returned to compressor 1 after going through first solenoid valve 4, first capillary tube 5 and first evaporator 6, thereby forming a first refrigerant circuit. In parallel to the foregoing first refrigerant circuit is formed a second refrigerant circuit starting from refrigerant branching unit 3, passing second solenoid 7, second capillary tube 8 and second evaporator 9, and returning to compressor 1.
First evaporator 6 is installed in first cooling compartment 11 of refrigerator""s main body 10 and second evaporator 9 is installed in second cooling compartment 12. First controlling means 13 detects the temperatures in first cooling compartment 11 and controls closing/opening of first solenoid 4. Second controlling means 14 detects the temperatures in second cooling compartment 12 and controls closing/opening of second solenoid 7.
Next, a description is given to how the refrigerating unit structured as above operates.
A refrigerant is compressed by compressor 1 and condensed by dissipating heat in condenser 2. After passing refrigerant branching unit 3, the refrigerant is depressurized in first capillary tube 5 and evaporated in first evaporator 6 when first solenoid 4 is open, thereby providing cooling for first cooling compartment 11. First controlling means 13 controls closing/opening of first solenoid 4, thereby controlling first cooling compartment 11 to a predetermined temperature.
Similarly, the refrigerant branched at refrigerant branching unit 3 is depressurized in second capillary tube 8 and evaporated in second evaporator 9 when second solenoid 7 is open, thereby providing cooling for second cooling compartment 12. Second controlling means 14 controls closing/opening of second solenoid 7, thereby controlling second cooling compartment 12 to a predetermined temperature. When the respective cooling compartments are not allowed to be controlled only by closing/opening of the respective solenoids, the respective cooling compartments are controlled by operating and stopping of compressor 1.
A prior art refrigerator is disclosed in the Japanese Patent Application Unexamined Publication No. H8-210753 of 1996.
A description is given to the aforementioned prior art refrigerator with reference to drawings.
FIG. 10 is a longitudinal cross-sectional view for showing an outline structure of the prior art refrigerator. FIG. 11 is a block diagram of a cooling system of the prior art refrigerator. FIG. 12 is a block diagram for showing an operation control circuit of the prior art refrigerator.
In FIG. 10, refrigerator""s main body 15 has freezer compartment 16 and cold storage compartment 17 that are separated from each other to prevent chilled air from mixing therebetween. First evaporator 18 is installed in freezer compartment 16 and second evaporator 19 is installed in cold storage compartment 17. First air blower 20 is disposed right next to first evaporator 18 and second air blower 21 is disposed right next to second evaporator 19. Compressor 22 is installed in the lower back part of refrigerator""s main body 15.
In FIG. 11, compressor 22, condenser 23, capillary tube 24 acting as a pressure reducer, first evaporator 18, refrigerant tube 25 and second evaporator 19 are connected in succession, thereby establishing a closed circuit. Refrigerant tube 25 connects between first evaporator 18 and second evaporator 19.
Subsequently, as FIG. 12 shows, freezer compartment temperature adjusting unit 27 to set up the temperatures of freezer compartment 16, cold storage compartment temperature adjusting unit 28 to set the temperatures of cold storage compartment 17, freezer compartment temperature detecting means 29 to detect the temperatures of freezer compartment 16 and cold storage compartment temperature detecting means 30 to detect the temperatures of cold storage compartment 17 are connected to the input terminal of controlling means 26 acting as a controller. First relay 31 and second relay 32 are connected to the output terminal of controlling means 26.
First switch 34, which is turned on/off according to the behavior of first relay 31, is connected to one of the terminals of power supply 33. Compressor 22 and second switch 35 are connected to the output terminal of first switch 34. Aforementioned first air blower 20 is connected to contact a of second switch 35. Aforementioned second air blower 21 is connected to contact b of second switch 35.
Next, a description is given to how the refrigerator structured as above operates.
A refrigerant is compressed by compressor 22 and condensed by dissipating heat in condenser 23. The condensed refrigerant is reduced in pressure in capillary tube 24 and part of the refrigerant is evaporated in first evaporator 18 and the balance of the refrigerant is evaporated while passing through second evaporator 19. Thus, a heat exchange reaction takes place in the respective evaporators. Then, the refrigerant in a gaseous state is sucked into compressor 22. Such a refrigeration cycle as above is repeated as compressor 22 is brought into operation.
By the action of a mechanical draft of first air blower 20 and second air blower 21, the air in freezer compartment 16 and cold storage compartment 17 undergoes a heat exchange in first evaporator 18 and second evaporator 19.
At this time, when the temperature detected by freezer compartment temperature detecting means 29 is higher than the temperature set up by freezer compartment temperature adjusting unit 27, controlling means 26 brings first relay 31 into operation to turn on first switch 34, thereby bringing compressor 22 into operation. Further, when the temperature detected by cold storage compartment temperature detecting means 30 is higher than the temperature set up by cold storage compartment temperature adjuster 28, controlling means 26 connects second relay 32 to contact b of second switch 35, thereby bringing second air blower 21 into operation. As a result, cold storage compartment 17 undergoes cooling selectively and is controlled to a predetermined temperature.
On the other hand, when the temperature detected by freezer compartment detecting means 29 is higher than the temperature set up by freezer compartment temperature adjusting unit 27 and the temperature detected by cold storage compartment temperature detecting means 30 is lower than the temperature set up by cold storage compartment temperature adjusting unit 28, controlling means 26 connects second relay 32 to contact a of second switch 35, thereby bringing first air blower 20 into operation. As a result, freezer compartment 16 undergoes cooling selectively and is controlled to a predetermined temperature.
When the temperature detected by freezer compartment temperature detecting means 29 is lower than the temperature set up by freezer compartment temperature adjusting unit 27, controlling means 26 brings first relay 31 into operation to turn off first switch 34, thereby bringing compressor 22 to a halt.
However, the structure of the prior art refrigerating unit is such that cooling control of each respective cooling compartment is exercised by on/off of respective solenoids or operation/halt of respective compressors, thereby bringing about big fluctuations in temperature of respective evaporators and also cooling compartments. As a result, there exists a drawback of the inability to maintain good quality of what is stored for a long period.
Since a capillary tube is used as a pressure reducing means for each respective evaporator, the evaporation temperature of each respective evaporator is determined by the entrance pressure of the evaporator. Therefore, the evaporator""s evaporation temperature is not variable and uncontrollable. As result, the efficiency of a refrigerating unit is not enhanced sufficiently and there exists a drawback of not allowing the electric power consumption to be reduced enough.
The present invention is to provide a high efficiency refrigerating unit by allowing the temperature variation of an object to be cooled caused by an evaporator to be minimized.
In the structure of the prior art refrigerator as described in above, first evaporator 18 and second evaporator 19 linked by refrigerant tube 25 and, therefore, the evaporation temperatures of respective evaporators are almost the same. In addition, since cooling control of freezer compartment 16 and cold storage compartment 17 is exercised by operation control of first air blower 20 and second air blower 21, electric power is consumed wastefully, in particular, due to a decline in cooling efficiency caused by cooling at an unnecessarily low temperature that takes place in cold storage compartment 17 where great temperature differentials exist in comparison with the evaporation temperature. Further, a compartment temperature variation and a humidity decline occur, thereby bringing about such a drawback as degrading the quality of foods in storage due to temperature stresses imposed on the foods or accelerated drying of the foods.
The present invention provides a refrigerator exhibiting a high cooling efficiency and achieving high storage quality of foods by bringing the evaporation temperature of each respective evaporator closer to the temperature set up for each respective cooling compartment.
A refrigerating unit of the present invention comprises:
(a) a compressor;
(b) a condenser;
(c) a plurality of evaporators connected in series;
(d) a capillary tube disposed between the condenser and each of the plurality of evaporators;
(e) a refrigerant flow rate adjustable unit disposed between respective evaporators of the plurality of evaporators; and
(f) a refrigerant,
in which the compressor, condenser, evaporator, capillary tube, refrigerant flow rate adjustable unit and refrigerant constitute a refrigeration cycle,
the refrigerant is circulated in the refrigeration cycle, and
the refrigerant flow rate adjustable unit controls respective evaporation temperatures of the plurality of evaporators.
The refrigerant flow rate adjustable unit is preferred to control a flow of the refrigerant in such a way as the evaporation temperature of each respective evaporator located at the upstream side of the refrigeration cycle is made higher than the evaporation temperature of each respective evaporator located at the downstream side of the refrigeration cycle.
Preferably, the refrigerating unit further comprises:
(f) a bypass circuit to bypass at least one evaporator of the plurality of evaporators,
in which the bypass circuit is disposed in parallel with the at least one evaporator,
the compressor, condenser, evaporator, capillary tube, refrigerant flow rate adjustable unit, bypass circuit and refrigerant constitute a refrigeration cycle,
the refrigerant is circulated in the refrigeration cycle, and
the refrigerant flow rate adjustable unit controls respective evaporation temperatures of the plurality of evaporators variably.
A refrigerator of the present invention comprises a plurality of cooling compartments and the refrigerating unit as described in above.
It is also preferred that each respective cooling compartment of the plurality of cooling compartments has a set up temperature that is different from one another, the evaporators are disposed in a cooling compartment of the plurality of cooling compartments, respectively, and the respective evaporators located at the upstream side of the refrigeration cycle are, in succession, disposed in a cooling compartment having a higher set up temperature.
Accordingly, each respective evaporator has a proper evaporation temperature. Therefore, the refrigeration cycle efficiency is enhanced, resulting in a reduction of the amount of energy consumed. In addition to achieving the foregoing advantage, a refrigerator having enhanced storage quality for the foods stored is made available.