JPH11311465A - Refrigerator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently perform cooling and reduce power consumption, by using a compressor where rotation can be controlled, changing the flow of a refrigerant via a three-way switching valve, and combining a pressure-reducing device for obtaining a high evaporation temperature. SOLUTION: A refrigerator is provided with a controllable compressor 10, a condenser 11 for emitting a high-temperature/high-voltage refrigerant gas from the compressor for liquefying, or the like. The refrigerant is provided with a solenoid valve 18a, check valves 17a and 17b, or the like for opening/closing the channel of a pressure- reducing device 14a and is also provided with a three-directional valve 13 between the discharge side of the compressor and the condenser. When a refrigeration chamber is operated, the solenoid valve 18a is released and the solenoid valve 18b is closed. On the other hand, when a freezer chamber is operated, the solenoid valve 18b is released and the solenoid valve 18a is closed. Also, when the compressor stops, two solenoid valves are closed, thus sealing a refrigerant flowing in and stays at an evaporator when the evaporator 11 and the compressor 10 that are not performing cooling stop for preventing temperature increase in the evaporator, thus reducing loss being generated due to the heat insulation operation of the refrigeration cycle. Also, by releasing the three-way valve 3 to the suction side before starting the compressor, power consumption is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigerator in which refrigerators and freezers are provided with dedicated evaporators, respectively, and a high-temperature side evaporating temperature for a refrigerator according to a combination of a rotational speed of a rotational speed control compressor and a pressure reducing device. And operation of the low-temperature side evaporation temperature for the freezer compartment,
The present invention relates to a refrigeration cycle for efficiently cooling a refrigerator.

[0002]

2. Description of the Related Art As a conventional two-temperature evaporation refrigeration cycle apparatus, Japanese Patent Application Laid-Open No. Hei 9-170732 and Japanese Patent Application Laid-Open No. Hei 9-509732 are listed. In Japanese Patent Application Laid-Open No. 9-17832, in order to efficiently exert the cooling power of the high-temperature side evaporator in which the amount of circulating refrigerant is increased, the refrigerant after the evaporator flows out is exchanged with the refrigerant after the high-temperature side evaporator, and the high-temperature side evaporator is exchanged. Is trying to make up for its heat exchange capacity.

However, in an actual refrigerator, the required cooling performance in the high temperature side, that is, in the refrigerator compartment is much smaller than that in the freezer compartment. Conversely, limiting the cooling power is suitable for high efficiency operation of the refrigerator. Therefore, when cooling the refrigerating compartment, the amount of circulating refrigerant is reduced, and the size of the evaporator and the pressure reducing device are optimized in accordance with the amount of circulating, so that highly efficient operation can be performed with a small cooling capacity. it can. In addition, when cooling the freezing compartment, the amount of circulation of the refrigerant is increased, and the size of the evaporator and the pressure reducing device are adjusted to the amount of the refrigerant to optimize the amount.
Highly efficient operation can be performed with a large cooling capacity.

On the other hand, in a tandem type cooling system disclosed in Japanese Patent Publication No. 9-509732, a high-temperature side evaporator and a low-temperature side evaporator are connected in series, and a fan installed in each evaporator is provided. It is stated that a refrigerator can be efficiently cooled by operating a refrigerator fan when cooling of the refrigerator compartment is required and by operating a freezer fan when cooling of the freezer compartment is required.

[0005] However, for example, when cooling the freezing room, it is necessary to control the evaporation temperature level of the evaporator for the freezing room to a considerably low temperature. Is set. At this time, only one decompression device is installed during the cycle,
The low-temperature refrigerant circulates also in the evaporator installed in the refrigerator compartment. Even if the operation of the fan is stopped and a small evaporator is installed, the evaporator is always in a low temperature state while the compressor is operating, and as described above, in a refrigerator having a very small required cooling capacity, There is a possibility that the state will be too cold even with natural convection cooling.

[0006]

SUMMARY OF THE INVENTION The present invention has the above disadvantages,
In other words, in a refrigeration cycle having two evaporators at different temperature levels, in order to improve the cooling of the refrigerator compartment which does not require much cooling capacity at high temperature, a small cooling chamber evaporator having a very small cooling capacity is required. It is necessary to use a heat exchanger, limit the flow rate of the refrigerant circulating through the evaporator, and install a decompression device that raises the temperature at which the refrigerant evaporates.

Further, a large-sized heat exchanger is installed in a low-temperature evaporator for a freezing room that requires a large cooling capacity, the amount of circulating refrigerant flowing therethrough is increased, and the pressure is reduced to lower the evaporation temperature of the refrigerant. It is necessary to provide an apparatus and to install a flow path switching valve for independently circulating the refrigerant flowing through these two evaporators.

[0008]

In order to solve the above problems, a compressor of a rotational speed control type capable of varying the circulating flow rate of a refrigerant is used. When the refrigerator is cooled, the compressor is operated at a low speed. This can be achieved by reducing the circulation flow rate of the refrigerant and flowing into a refrigerator evaporator through a decompression device for obtaining a required high evaporating temperature. This can be achieved by increasing the number of the refrigerants to increase the circulation amount of the refrigerant and flowing the refrigerant into the freezer evaporator through a pressure reducing device for obtaining a required low-temperature evaporation temperature.

In order to cool the refrigerator compartment and the freezer compartment independently of each other, the refrigerant flows between the condenser and the evaporator based on the inflow from the condenser to the refrigerator compartment or the freezer compartment evaporator. By installing a three-way switching valve that changes the path, a refrigeration cycle for performing the above cooling can be configured.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIG. 10 is a compressor whose rotation speed can be controlled, 11
Is a condenser for releasing and liquefying the high-temperature and high-pressure refrigerant gas discharged from the compressor, 12 is a dryer for removing moisture in the cycle, and 13 is a refrigerant passage for the refrigerator compartment evaporator 15a or the freezer compartment evaporator 15b. This is a three-way switching valve for switching. 14a is a decompression device for the evaporator 15a, 14b is the evaporator 1
A decompression device for 5b, 16a is a decompression device 14a and an evaporator 15
Reference numeral 16b denotes a portion that makes contact with the outlet pipe and performs heat exchange, and reference numeral 16b denotes a portion that makes contact between the pressure reducing device 14b and the outlet pipe of the evaporator 15b to perform heat exchange.

A check valve 17 allows the refrigerant to flow only in one direction. The check valve 17 opens the three-way valve to the refrigerating compartment evaporator during the cooling operation of the refrigerating compartment and when the compressor is stopped. This is to prevent the refrigerant from condensing in the evaporator.
The temperature in the refrigerator is normally kept at about 5 ° C. in the refrigerator compartment and about −18 ° C. in the freezer compartment.

When the refrigerator is cooled in such a refrigeration cycle, it is necessary to raise the evaporation temperature (pressure rise) as shown on the Ph diagram of the refrigerant in FIG. Since the specific volume (volume / unit mass) becomes a small value, when a conventional compressor with a fixed rotation speed is used, the circulation amount of the refrigerant increases, and the cooling obtained by the product of this circulation amount and the enthalpy difference Δha The amount will increase.

In a normal refrigerator, the required amount of cooling between the refrigerating compartment and the freezing compartment is about 1: 4. In order to reduce the amount of cooling in the refrigerating compartment, it is necessary to rotate the compressor constructed as in the present invention. What is necessary is just to reduce the number and reduce the circulation amount of the refrigerant.

Further, since the condenser designed in consideration of the cooling of the freezing room due to the reduced circulation amount has a large capacity, it can be operated at a low condensing temperature (low pressure). (Compression ratio) can be reduced, and the operating efficiency of the refrigeration cycle and the compressor can be improved.

FIG. 2 shows the relationship between the efficiency of the compressor during the operation of the refrigerator and the operation of the refrigerator at different compression ratios with respect to the rotation speed of the compressor. Efficiency is improved on the low-speed side of the compressor rotation speed, and the efficiency of the refrigerator compartment operation with a small compression ratio is also improved. By setting the rotation speed range of the compressor according to the required amount of cooling, low power consumption is achieved. A refrigeration cycle for a refrigerator can be configured.

FIG. 4 shows another embodiment, in which a solenoid valve 18a for opening and closing a flow path is provided upstream of the refrigerator compartment pressure reducing device 14a, a check valve 17a is provided downstream, and a solenoid valve is provided upstream of the freezing compartment reducing device 14b. 18b, a check valve 17b is installed downstream, and a three-way valve 13 is installed between the discharge side of the compressor and the condenser. In the refrigerator operation, the solenoid valve 18a is opened and the solenoid valve 18b is opened. In the freezer operation, the solenoid valve 18b is opened and the solenoid valve 18a is closed in the freezer operation, and the two solenoid valves are closed when the compressor is stopped to flow into the evaporator that is not cooling and to the evaporator when the compressor is stopped. It is possible to prevent the temperature of the evaporator from rising by sealing the refrigerant to be retained, thereby reducing the loss caused by the intermittent operation of the refrigeration cycle.

Further, by opening the three-way valve to the suction side of the compressor before starting the compressor, the pressure in the compressor can be balanced, the required torque of the compressor can be reduced, and the power consumption of the refrigerator can be reduced. Refrigeration cycle configuration.

[0018]

As described above, according to the present invention, the compressor of which the rotation speed can be controlled is used, and the refrigerant evaporator for the refrigerating compartment and the evaporator for the refrigerating compartment are independently controlled via the three-way switching valve. When the refrigerating chamber is cooled by changing the flow path, the number of rotations of the compressor is operated in a low speed range corresponding to the small evaporator, and a high efficiency refrigerating When cooling and freezing the refrigerator, the compressor operates at a high speed in accordance with the large evaporator and operates in a high-speed range. Can be cooled, and the effect of reducing the power consumption of the refrigerator can be obtained.

Further, in the present invention, an expansion valve may be used as a more detailed evaporating temperature control as a pressure reducing device, and a refrigerant pipe is fixed to a single flat plate as an evaporator for a refrigerator having a small cooling amount. By using a plate-type heat exchanger, a cross-fin type heat exchanger in which a plurality of fins having a plurality of holes are laminated as a freezer compartment evaporator having a large cooling amount, and a pipe is fixed through the hole. An inexpensive and compact refrigeration cycle can be configured, and at the same time, the temperature level of the evaporator for the refrigerator compartment is high, which can dehumidify the refrigerated room air with a lot of moisture. Practical effects can also be obtained, such as increasing the density of the fin stack of the freezer evaporator.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a refrigeration cycle in which a rotation speed control compressor according to the present invention and an independent evaporator are installed in a refrigerator compartment and a freezer compartment.

FIG. 2 is a characteristic diagram showing the efficiency of the compressor according to the present invention divided into a rotation speed, a refrigerator operation, and a freezer operation.

FIG. 3 is a characteristic diagram showing a refrigerant room operating state and a freezing room operating state according to the present invention on a Ph diagram of a refrigerant.

FIG. 4 is a configuration diagram of a refrigeration cycle showing another embodiment of the present invention.

FIG. 5 is a configuration diagram of a conventional refrigeration cycle having two independent evaporators.

FIG. 6 is a configuration diagram of a conventional refrigeration cycle having two independent evaporators and connecting each evaporator in series.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 ... Rotation speed control compressor, 11 ... Condenser, 12 ... Dryer, 13 ... Three-way switching valve, 14a ... Refrigerator decompression device,
14b: decompression device for freezer compartment, 15a: evaporator for refrigerator compartment,
15b ... Evaporator for freezer compartment, 16a ... Refrigerator compartment side heat exchange part, 16b ... Refrigerator compartment side heat exchange part, 17a ... Check valve for refrigerator compartment evaporator, 17b ... Check valve for freezer compartment evaporator, 18a ...
Refrigerating room side solenoid valve, 18b ... freezing room side solenoid valve.

Continuing from the front page (72) Inventor Shibata ▲ Ko ▼ Ichi 800 Tomita, Ohira-cho, Shimotsuga-gun, Tochigi Prefecture Inside the Cooling and Refrigerating Division, Hitachi, Ltd. Hitachi, Ltd.

Claims (1)

[Claims] 1. A refrigeration cycle comprising a rotational speed control compressor, a condenser, a decompression device, and an evaporator, which are sequentially connected.
The evaporator has an evaporator dedicated to the refrigerator compartment with a high evaporation temperature level and an evaporator dedicated to the freezer compartment with a low evaporation temperature level. The evaporator for the refrigerator compartment is a compressor operated at a low speed range and a decompression device with a small decompression amount. The refrigerator is characterized in that the freezer evaporator is evaporated by a combination of a compressor operated at a higher speed than the refrigerator compartment cooling and a pressure reducing device having a large pressure reduction amount.