JP2001201235A - Refrigerator-freezer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve high efficiency by a wide ranging capacity control concerning a refrigerator-freezer, using a double-stage compression system. SOLUTION: There are arranged a refrigerator-freezer body having a freezer compartment and a refrigerator compartment, low stage side compressor 10, high stage side compressor 12, condenser 5, low-stage side capillary 6, low-stage side flow rate adjuster 14 which is provided between the condenser 5 and the low stage side capillary 6 for adjusting the flow rate of a refrigerant to the low-stage side capillary 6, low-stage side evaporator 8 for cooling the freezer compartment, low-stage side suction tube 11 provided between the low-stage side evaporator 8 and the low-stage side compressor 10, high-stage side capillary 7, high-stage side flow rate adjuster 15 which is provided between the condenser 5 and the high-stage side capillary 7 for adjusting the flow rate of the refrigerant to the high-stage side capillary 7, high-stage side evaporator 9 for cooling the refrigerator compartment, and high-stage side suction tube 13 provided between the high stage side evaporator 9 and the high-stage side compressor 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigerator using a two-stage compression system, and more particularly to an improvement in efficiency.

[0002]

2. Description of the Related Art A conventional refrigerator-freezer is disclosed in
Japanese Unexamined Patent Publication (Kokai) No. 223497/1995 discloses an example. Hereinafter, an example of the conventional refrigerator-freezer will be described with reference to the drawings.

FIG. 13 shows a conventional configuration. In FIG. 13, reference numeral 1 denotes a cooling system, which includes a compressor 4, a condenser 5, a low-stage capillary 6, a high-stage capillary 7, and a low-stage compressor having a low-stage compression unit 2 and a high-stage compression unit 3 therein. And a high-stage evaporator 9.

The operation of the refrigerator having the above-described structure will be described below. High-stage compression section 3 of compressor 4
The high-pressure refrigerant discharged from the condenser is condensed in the condenser 5 and then divided, and one of the refrigerant flows from the low-stage capillary 6 to the low-stage evaporator 8 via the high-stage evaporator 9, It is sucked into the side compression part. The other flows from the high-stage capillary 7 to the high-stage evaporator 9 and is sucked into the compressor 4.

The refrigerant sucked into the compressor 4 is mixed with the refrigerant discharged from the low-stage compression section 2 and is sucked into the high-stage compression section 3.

At this time, since the refrigerant flowing from the condenser 5 to the low-stage capillary 6 is cooled by the high-stage evaporator 9, sufficient supercooling can be ensured. Since the refrigerating capacity can be increased, efficiency can be improved.

[0007]

However, in the above-described conventional configuration, the flow rate of the refrigerant flowing to the low-stage evaporator 8 and the high-stage evaporator 9 cannot be controlled, and when there is a large load fluctuation, etc. There is a possibility that either one of the refrigerating capacity becomes excessive or insufficient, and the refrigerating / refrigerator capacity becomes insufficient or the efficiency is reduced.

The present invention has been made to solve the above-mentioned conventional problems, and has as its object to control the capacity of each evaporator in response to a large load change.

[0009] When one of the freezer compartment and the refrigerator compartment has reached the target temperature, but the other compartment has not reached the target temperature, the cooling operation is continued. Was a wasteful operation, and the efficiency of the refrigerator could be reduced.

[0010] Another object of the present invention is to improve the efficiency of a refrigerator-freezer by avoiding unnecessary operation.

Further, in the above-mentioned conventional configuration, only the high-stage evaporator 9 can exchange heat with the low-stage capillary 6, the load in the refrigerator compartment increases, and the refrigerating capacity of the high-stage evaporator 9 is required. In any case, since the refrigerating capacity of the high-stage evaporator 9 is used for supercooling of the low-stage evaporator 9, there is a possibility that the capacity of the refrigerator compartment may be insufficient due to the insufficient refrigerating capacity of the high-stage evaporator 9.

Another object of the present invention is to provide a refrigerator with high efficiency by optimizing means for supercooling.

When the load on one of the freezing compartment and the refrigerator compartment becomes small and the capacity becomes excessive, the compressor 4 sucks the liquid refrigerant due to the excess capacity, and the reliability of the compressor 4 is increased by the liquid compression and non-lubrication operation. There was a fear that the property was reduced.

Another object of the present invention is to provide a highly reliable refrigerator-freezer in which the compressor does not draw in the liquid refrigerant even when the capacity becomes excessive.

In the above-mentioned conventional configuration, the cooling operation is continued for a certain period of time, and in the defrosting operation in which the frost adhering to the low-stage evaporator 8 or the high-stage evaporator 9 is released, a heater or the like for releasing the frost is provided. Therefore, the power consumption of the refrigerator becomes higher than in the normal cooling operation, and the efficiency of the refrigerator is reduced.

Another object of the present invention is to provide a high-efficiency refrigerator-freezer by performing a defrosting operation without using a defrosting means such as a heater.

[0017]

SUMMARY OF THE INVENTION In order to solve this problem, a refrigerator according to the present invention comprises a refrigerator-freezer body having a freezer compartment and a refrigerator compartment, a low-stage compressor, a high-stage compressor, and a condenser. And a low-stage capillary, a low-stage flow control device provided between the condenser and the low-stage capillary to adjust the flow rate of the refrigerant to the low-stage capillary, and a low-stage evaporator that cools the freezing chamber. The low-stage suction pipe provided between the low-stage evaporator and the low-stage compressor, the high-stage capillary, and the refrigerant flow to the high-stage capillary provided between the condenser and the high-stage capillary. The configuration includes a high-stage flow control device for adjusting, a high-stage evaporator for cooling the refrigerator, and a high-stage suction pipe provided between the high-stage evaporator and the high-stage compressor.

As a result, the flow rate of the refrigerant flowing through each evaporator can be controlled, and a high-efficiency refrigerator-freezer that can cope with a wide range of load fluctuations can be provided.

Further, a check valve is provided on the high-stage suction pipe, and an operation of stopping the refrigerant is added to the low-stage flow control device and the high-stage flow control device.

[0020] Thus, the refrigerant can be prevented from flowing into one of the evaporators, and a high-efficiency refrigerator-freezer corresponding to a wider load variation can be obtained.

Further, the high-stage capillary is brought into close contact with the high-stage suction pipe.

As a result, the refrigerating effect of the high-stage evaporator can be enhanced, the refrigerating capacity of the high-stage evaporator can be increased, and a high-efficiency refrigerator-freezer can be obtained.

Further, the low-stage capillary is closely attached to the low-stage suction pipe.

Thus, the refrigerating effect of the low-stage evaporator can be enhanced, the refrigerating capacity of the low-stage evaporator can be increased, and a high-efficiency refrigerator-freezer can be obtained.

The high-stage second capillary, which is provided between the high-stage flow control device and the high-stage evaporator and is in close contact with the low-stage suction pipe, and the refrigerant that has exited the condenser are usually supplied to the high-stage A high-stage switching valve that flows into the high-side second capillary when the load in the freezing compartment is small and the capacity of the low-stage evaporator becomes excessive when flowing into the high-side capillary.

Thus, when the refrigerating capacity of the low-stage evaporator is excessive, the low-stage compressor does not suck in the liquid refrigerant and lowers the reliability, thereby providing a highly reliable refrigerator.

The high-stage second capillary, which is provided between the high-stage flow controller and the high-stage evaporator and is in close contact with the low-stage evaporator, and the refrigerant that has exited the condenser are usually supplied to the high-stage evaporator. A high-stage switching valve that flows into the high-side second capillary when the load in the freezing compartment is small and the capacity of the low-stage evaporator becomes excessive when flowing into the high-side capillary.

Thus, when the refrigerating capacity of the low-stage evaporator is excessive, the excess refrigerating capacity can be used more for supercooling on the high-stage side, and a more efficient refrigerating refrigerator can be obtained. .

The low-stage second capillary, which is provided between the low-stage flow control device and the low-stage evaporator and is in close contact with the high-stage suction pipe, and the refrigerant that has exited the condenser are usually supplied to the low-stage evaporator. A low-stage switching valve that flows into the lower capillary and flows through the lower-stage second capillary when the load in the refrigerator compartment is small and the capacity of the higher-stage evaporator becomes excessive.

Thus, when the refrigerating capacity of the high-stage evaporator is excessive, the high-stage compressor does not suck the liquid refrigerant and lowers the reliability, thereby providing a highly reliable refrigerator.

The low-stage second capillary, which is provided between the low-stage flow controller and the low-stage evaporator and is in close contact with the high-stage evaporator, and the refrigerant that has exited the condenser are usually supplied to the low-stage evaporator. A low-stage switching valve that flows into the lower capillary and flows through the lower-stage second capillary when the load in the refrigerator compartment is small and the capacity of the higher-stage evaporator becomes excessive.

Thus, when the refrigerating capacity of the high-stage evaporator is excessive, the excess refrigerating capacity can be used more for supercooling on the low-stage side, and a more efficient refrigerating refrigerator can be obtained. .

Also, a discharge pipe provided between the low-stage compressor and the high-stage compressor, and a discharge pipe provided between the low-stage compressor and the high-stage compressor and closely attached to the high-stage evaporator. The stage-side second discharge pipe and the refrigerant discharged from the low-stage compressor normally flow to the high-stage compressor through the discharge pipe, and the load of the refrigerator compartment is small and the capacity of the high-stage evaporator becomes excessive. A configuration is provided that includes a low-stage discharge switching valve that sometimes flows into the low-stage second discharge pipe.

Thus, when the refrigerating capacity of the high-stage evaporator is excessive, the excessive refrigerating capacity can be used to reduce the temperature of the suction gas of the high-stage compressor, thereby providing an efficient refrigerating refrigerator. be able to.

Further, a discharge pipe provided between the low-stage compressor and the high-stage compressor, and a discharge pipe provided between the low-stage compressor and the high-stage compressor and closely attached to the low-stage evaporator. The refrigerant discharged from the stage-side third discharge pipe and the low-stage compressor is usually passed to the high-stage compressor through the discharge pipe, so that the freezing compartment load is small and the capacity of the low-stage evaporator becomes excessive. In this case, a low-stage discharge switching valve that flows to the low-stage third discharge pipe at the time of discharge is provided.

Thus, when the refrigerating capacity of the low-stage evaporator is excessive, the excessive refrigerating capacity can be used to reduce the temperature of the suction gas of the high-stage compressor, thereby providing an efficient refrigerating refrigerator. be able to.

A second condenser is provided between the high-stage compressor and the high-stage flow control device and the low-stage flow control device and is in close contact with the high-stage evaporator. The discharged refrigerant is usually passed only through the condenser to the high-stage flow control device and the low-stage flow control device, and during the defrosting operation to dissolve the frost adhering to the high-stage evaporator, the condenser and the second condenser A defrost valve was provided to flow through the vessel to the high-stage flow control device and the low-stage flow control device.

Thus, the supercooling of the condenser can be increased by utilizing the cooling power of the frost during the defrosting operation of the high-stage evaporator, and the efficiency is high even during the defrosting operation of the high-stage evaporator. It can be a refrigerator-freezer.

A third condenser is provided between the high-stage compressor and the high-stage flow control device and the low-stage flow control device and is in close contact with the low-stage evaporator. The discharged refrigerant is usually passed only through the condenser to the high-stage flow control device and the low-stage flow control device, and during the defrosting operation in which the frost adhering to the low-stage evaporator is released, the condenser and the third condenser are removed. A defrost valve was provided to flow through the vessel to the high-stage flow control device and the low-stage flow control device.

Thus, the supercooling of the condenser can be increased by utilizing the cooling power of the frost during the defrosting operation of the low-stage evaporator, and the efficiency is high even during the defrosting operation of the low-stage evaporator. It can be a refrigerator-freezer.

[0041]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention is directed to a refrigerator-freezer body having a freezer compartment and a refrigerator compartment, a low-stage compressor, a high-stage compressor, a condenser, A stage-side capillary, a low-stage-side flow control device provided between the condenser and the low-stage-side capillary for adjusting the flow rate of the refrigerant to the low-stage-side capillary, a low-stage-side evaporator for cooling the freezing chamber, and a low-stage-side A low-stage suction pipe provided between the evaporator and the low-stage compressor, a high-stage capillary, and a high-stage provided between the condenser and the high-stage capillary to regulate the flow rate of refrigerant to the high-stage capillary Each of the evaporators is provided with a side flow rate control device, a high-stage evaporator for cooling the refrigerator compartment, and a high-stage suction pipe provided between the high-stage evaporator and the high-stage compressor. To control the flow rate of refrigerant flowing through the refrigerator, and to provide a high-efficiency refrigerator-freezer that responds to a wide range of load fluctuations It can be.

According to a second aspect of the present invention, a check valve is provided on the high-stage suction pipe, and an operation for stopping the refrigerant is added to the low-stage flow control device and the high-stage flow control device. As a result, the refrigerant could not flow into either evaporator,
A highly efficient refrigerator-freezer corresponding to a wider range of load fluctuations can be provided.

According to the third aspect of the present invention, since the high-stage capillary is in close contact with the high-stage suction pipe, the refrigerating effect of the high-stage evaporator can be increased.
The refrigerating capacity of the high-stage evaporator also increases, and a highly efficient refrigerator-freezer can be obtained.

In the invention according to claim 4 of the present invention, the low-stage capillary is in close contact with the low-stage suction pipe, so that the refrigerating effect of the low-stage evaporator can be enhanced.
The refrigerating capacity of the low-stage evaporator also increases, and a high-efficiency refrigerator-freezer can be obtained.

According to a fifth aspect of the present invention, there is provided a high-stage second capillary which is provided between a high-stage flow control device and a high-stage evaporator and is in close contact with a low-stage suction pipe; With a high-stage switching valve that normally flows the refrigerant that has flowed out through the high-stage capillary, and flows through the high-stage second capillary when the freezer compartment load is small and the low-stage evaporator capacity is excessive. Therefore, when the refrigerating capacity of the low-stage evaporator is excessive, the low-stage compressor can prevent the liquid refrigerant from being sucked in and reduce the reliability, thereby providing a highly reliable refrigerator.

According to a sixth aspect of the present invention, there is provided a high-stage second capillary which is provided between a high-stage flow control device and a high-stage evaporator and is in close contact with the low-stage evaporator; With a high-stage switching valve that normally flows the refrigerant that has flowed out through the high-stage capillary, and flows through the high-stage second capillary when the freezer compartment load is small and the low-stage evaporator capacity is excessive. Therefore, when the refrigerating capacity of the low-stage evaporator is excessive, the excess refrigerating capacity can be used more for supercooling on the high-stage side, and a more efficient refrigerating refrigerator can be obtained.

According to a seventh aspect of the present invention, there is provided a low-stage second capillary which is provided between a low-stage flow control device and a low-stage evaporator and is in close contact with a high-stage suction pipe; With a low-stage switching valve that normally flows the refrigerant that has flowed out to the low-stage capillary, and flows to the low-stage second capillary when the load of the refrigerator compartment is small and the capacity of the high-stage evaporator becomes excessive. Therefore, it is possible to prevent the high-stage compressor from sucking the liquid refrigerant to lower the reliability when the refrigerating capacity of the high-stage evaporator is excessive, and to provide a highly reliable refrigerator.

The invention according to claim 8 of the present invention provides a low-stage second capillary which is provided between the low-stage flow controller and the low-stage evaporator and is in close contact with the high-stage evaporator; With a low-stage switching valve that normally flows the refrigerant that has flowed out to the low-stage capillary, and flows to the low-stage second capillary when the load of the refrigerator compartment is small and the capacity of the high-stage evaporator becomes excessive. Therefore, when the refrigerating capacity of the high-stage evaporator is excessive, the excess refrigerating capacity can be used more for subcooling on the low-stage side, and a more efficient refrigerating refrigerator can be obtained.

According to a ninth aspect of the present invention, there is provided a discharge pipe provided between a low-stage compressor and a high-stage compressor, and a discharge pipe provided between a low-stage compressor and a high-stage compressor. The refrigerant discharged from the low-stage second discharge pipe, which is in close contact with the high-stage evaporator, and the refrigerant discharged from the low-stage compressor are usually passed through the discharge pipe to the high-stage compressor, so that the load in the refrigerator compartment is small and the high stage When the refrigerating capacity of the high-stage evaporator is excessive, the system is equipped with a low-stage discharge switching valve that flows to the low-stage second discharge pipe when the capacity of the high-side evaporator becomes excessive. The temperature of the suction gas of the high-stage compressor can be reduced by using the capacity, and an efficient refrigerator-freezer can be provided.

According to a tenth aspect of the present invention, there is provided a discharge pipe provided between a low-stage compressor and a high-stage compressor, and a discharge pipe provided between a low-stage compressor and a high-stage compressor. The refrigerant discharged from the low-stage third compressor, which is in close contact with the low-stage evaporator, and the refrigerant discharged from the low-stage compressor are normally passed through the discharge tube to the high-stage compressor, so that the freezing compartment load is small and low. When the capacity of the stage evaporator becomes excessive, the low stage side discharge switching valve that flows to the low stage side third discharge pipe is provided, so when the refrigeration capacity of the low stage side evaporator is excessive, Using the refrigerating capacity, the temperature of the suction gas of the high-stage compressor can be reduced, and an efficient refrigerator-freezer can be provided.

An eleventh aspect of the present invention is directed to a second condenser provided between a high-stage compressor, a high-stage flow control device and a low-stage flow control device, and in close contact with a high-stage evaporator. The refrigerant discharged from the high-stage compressor and the high-stage compressor is usually passed only through the condenser to the high-stage flow control device and the low-stage flow control device to dissolve frost adhering to the high-stage evaporator. During the defrosting operation, a defrost valve is provided to flow through the condenser and the second condenser to the high-stage flow control device and the low-stage flow control device. The supercooling of the condenser can be increased by utilizing the cooling power of the above, and a high-efficiency refrigerator-freezer can be obtained even during the defrosting operation of the high-stage evaporator.

According to a twelfth aspect of the present invention, there is provided a third condenser provided between a high-stage compressor, a high-stage flow control device and a low-stage flow control device, and in close contact with a low-stage evaporator. The refrigerant discharged from the high-stage compressor and the high-stage compressor is usually passed only through the condenser to the high-stage flow control device and the low-stage flow control device to dissolve frost adhering to the low-stage evaporator. The defrosting operation is performed with a defrost valve that flows through the condenser and the third condenser to the high-stage flow control device and the low-stage flow control device. The supercooling of the condenser can be increased by utilizing the cooling power of the above, and a high-efficiency refrigerator-freezer can be obtained even during the defrosting operation of the low-stage evaporator.

Hereinafter, an embodiment of the present invention will be described with reference to FIG.
This will be described with reference to FIG. The same components as those in the related art are denoted by the same reference numerals, and detailed description thereof will be omitted.

(Embodiment 1) FIG. 1 is a cooling system diagram of a refrigerator-freezer according to Embodiment 1 of the present invention. In FIG. The refrigerant flowing through the stage-side suction pipe 11 is sucked and compressed, and then discharged. A high-stage compressor 12 sucks and compresses a refrigerant in which the refrigerant flowing from the high-stage evaporator 9 through the high-stage suction pipe 13 and the refrigerant discharged from the low-stage compressor 10 are discharged after compression. .

Reference numeral 14 denotes a low-stage flow control device provided between the condenser 5 and the low-stage capillary 6, which adjusts the flow rate of the refrigerant flowing from the condenser 5 to the low-stage capillary 6.
Reference numeral 15 denotes a high-stage flow control device provided between the condenser 5 and the high-stage capillary 7, which adjusts the flow rate of the refrigerant flowing from the condenser 5 to the high-stage capillary 7.

The operation of the refrigerator having the above-described structure will be described below. The refrigerant gas discharged from the high-stage compressor 12 flows into the condenser 5 and is liquefied, and is diverted to the low-stage flow control device 14 and the high-stage flow control device 15. The refrigerant flowing to the low-stage flow controller 14 is depressurized by the low-stage capillary 6, and is vaporized by the low-stage evaporator 8 to cool a freezing chamber (not shown) and to cool the low-stage suction pipe 11. The flow is sucked into the low-stage compressor 10.

The refrigerant flowing to the high-stage flow control device 15 is decompressed by the high-stage capillary 7, and vaporized by the high-stage evaporator 9 to cool a refrigerator (not shown) and to cool the refrigerator. After flowing through the side suction pipe 13 and being mixed with the refrigerant discharged from the low stage compressor, it is sucked into the high stage compressor 12.

At this time, the depressurized amount of the low-stage capillary 6 is larger than the depressurized amount of the high-stage capillary 7, and the temperature of each of the freezing room (not shown) and the refrigerating room (not shown) can be controlled. In this way, the evaporation temperature in the low-stage evaporator 8 is set to be lower than the target temperature of the freezing room, and the evaporation temperature in the high-stage evaporator 9 is set to be lower than the target temperature of the refrigerator compartment. The amount has been set.

Here, when the load of the refrigerator changes due to the opening and closing of the refrigerator door and the change of the outside air temperature, and the load of the refrigerator becomes large, the low-stage side flow control device 14
As a result, the flow rate of the refrigerant flowing through the low-stage capillary 6 is increased, and at the same time, the flow rate of the refrigerant flowing through the high-stage capillary 7 is reduced by the high-stage flow control device 15, whereby the refrigerating capacity of the low-stage evaporator 8 is increased. The freezer compartment can reach the target temperature in a shorter time.

When the load in the refrigerator becomes large due to the load fluctuation, the flow rate of the refrigerant flowing through the high-stage capillary 7 is increased by the high-stage flow control device 15, and at the same time, the low-stage flow control device 14 reduces the flow amount of the refrigerant. By reducing the flow rate of the refrigerant flowing through the stage side capillary 6, the refrigerating capacity of the high stage side evaporator 9 is increased, and the refrigerating room can reach the target temperature in a shorter time.

Thus, even when one of the freezer compartments or the refrigerator compartment becomes insufficient in capacity, the ratio of the refrigerating capacity of each room can be adjusted, and wasteful operation in which the refrigerating capacity of the other room becomes excessive. Never do.

Therefore, it is possible to prevent a decrease in efficiency due to a change in load, and to provide a highly efficient refrigerator-freezer.

In this embodiment, the method of determining the change in the load of the refrigerator compartment and the refrigerator compartment is not particularly limited. For example, the temperature of the low-stage evaporator 8, the temperature of the freezer compartment and the temperature of the high compartment The temperature of the side evaporator 9 and the temperature of the refrigerator compartment are each detected by a temperature detector such as a thermistor, and a temperature difference obtained by a known temperature difference calculating means is used as a criterion. The control can be easily performed when it is determined by the determining means realized by the above that the respective load amounts are increased.

In this embodiment, two compressors, the low-stage compressor 10 and the high-stage compressor 11, are used, but the low-stage compressor 2 and the high-stage compressor as in the conventional example are used. The same effect can be obtained even if one compressor having the side compression section 3 is used.

In the present embodiment, the two-stage compression system of the high-stage side and the low-stage side has been described as the cooling system. However, a similar effect can be obtained with a multi-stage compression system of three or more stages.

(Embodiment 2) FIG. 2 is a cooling system diagram of a refrigerator-freezer according to Embodiment 2 of the present invention. In FIG. 1, reference numeral 16 denotes a cooling system provided between the condenser 5 and the lower-stage capillary 6. This is a stage-side flow control device, which has an operation of adjusting the flow rate of the refrigerant to the low-stage side capillary 6 and stopping the flow of the refrigerant. Reference numeral 17 denotes a high-stage flow rate control device provided between the condenser 5 and the high-stage capillary.
Has the operation of adjusting the flow rate of the refrigerant to the refrigerant and stopping the flow of the refrigerant. Reference numeral 18 denotes a check valve provided on the high-stage suction pipe 13,
This prevents backflow of the refrigerant from the low-stage compressor 10 to the high-stage evaporator 9.

The operation of the refrigerator-freezer constructed as described above will be described below. When the load of the refrigerator changes due to the opening / closing of the freezer compartment or the refrigerator compartment door, a change in the outside air temperature, etc., when the refrigerator compartment has reached the target temperature but the freezer compartment has not reached the target temperature, the high temperature is set. Since the refrigerant stops flowing to the high-stage capillary 7 by the stage-side flow control device 17, the refrigerant flows only through the low-stage evaporator 8, and the freezing room is cooled to the target temperature in a shorter time without wasting the refrigerator. Can be reached. At this time, since the check valve 18 is provided in the high-stage suction pipe 13, the refrigerant discharged from the low-stage compressor 10 does not flow back to the low-temperature high-stage evaporator 10 to be condensed.

When the temperature of the refrigerating compartment has not reached the target temperature even though the temperature of the freezing compartment has reached the target temperature, the low-stage compressor 10 is stopped, and at the same time, the low-stage flow control device 16 is operated. Since the refrigerant does not flow through the stage-side capillary 6, the refrigerant flows only through the high-stage evaporator 9, and the refrigerating room can reach the target temperature in a shorter time without wasting the freezing room.

As a result, the capacity of one of the freezing room and the refrigerator room becomes insufficient, and the other room reaches the target temperature, so that the room reaching the target temperature is further cooled. Never do.

Accordingly, it is possible to prevent the efficiency from decreasing due to the load fluctuation, and it is possible to obtain a more efficient refrigerator-freezer.

In this embodiment, the first embodiment is also used.
The same effect can be obtained.

(Embodiment 3) FIG. 3 is a cooling system diagram of a refrigerator-freezer according to Embodiment 3 of the present invention. In FIG. 3, reference numeral 19 denotes a high-stage capillary which is in close contact with the high-stage suction pipe 13. .

The operation of the refrigerator-freezer constructed as described above will be described below. During the cooling operation, the temperature of the high-stage suction pipe 13 is normally lower than the outside air temperature, so that the outside air is uselessly cooled. Here, the high-stage capillary 19 is cooled by being in close contact with the high-stage suction pipe 13,
Even at the same reduced pressure, the dryness is small, the refrigeration effect is large, and the refrigeration capacity of the high-stage evaporator 9 is large.

As a result, the refrigerating capacity can be increased without unnecessary cooling of the outside air.

Accordingly, a high-efficiency refrigerator-freezer can be obtained by increasing the refrigerating capacity of the high-stage evaporator 9.

(Embodiment 4) FIG. 4 is a diagram showing a cooling system for a refrigerator according to Embodiment 4 of the present invention. In FIG. 4, reference numeral 20 denotes a low-stage capillary that is in close contact with the low-stage suction pipe 11. .

The operation of the refrigerator having the above-described structure will be described below. During the cooling operation, the temperature of the low-stage suction pipe 11 is usually lower than the outside air temperature, so that the outside air is uselessly cooled. Here, the low-stage capillary 20 is cooled by being in close contact with the high-stage suction pipe 11,
Even at the same reduced pressure, the dryness is small, the refrigerating effect is increased, and the refrigerating capacity of the low-stage evaporator 8 is increased.

Thus, the refrigerating capacity can be increased without unnecessary cooling of the outside air.

Therefore, a more efficient refrigerator-freezer can be provided by increasing the refrigerating capacity of the low-stage evaporator 8.

(Embodiment 5) FIG. 5 is a cooling system diagram of a refrigerator according to Embodiment 5 of the present invention. In FIG. 5, reference numeral 21 denotes a high-stage flow control device 17 and a high-stage evaporator 9. A high-stage second capillary which is provided between and is in close contact with the low-stage suction pipe 11. Normally, the refrigerant flows to the high-stage capillary 7 side, the freezing compartment load is small, and the low-stage evaporator 8 When the capacity becomes excessive, the second capillary 2 on the higher stage
1 is a high-stage side switching valve for flowing a refrigerant.

The operation of the refrigerator having the above-described structure will be described below. During normal operation, the refrigerant flowing through the high-stage flow control device 17 flows from the high-stage capillary 7 through the high-stage evaporator 9 and is sucked into the high-stage compressor 12.

Here, when the load in the freezing compartment is reduced and the refrigerating capacity of the low-stage evaporator 8 becomes excessive, the liquid refrigerant cannot be completely vaporized in the low-stage evaporator 8 and The liquid refrigerant also flows. At this time, the high-stage second capillary 21 exchanges heat with the low-stage suction pipe 11 by the high-stage switching valve 22, the liquid refrigerant in the low-stage suction pipe 11 is deprived of heat and vaporized, and the liquid refrigerant is low. It is not sucked into the stage compressor 10.

As a result, the excess liquid refrigerant of the low-stage evaporator 8 is sucked into the low-stage compressor 10, and the low-stage compressor 10 is destroyed by the liquid compression operation, and the sliding part is worn by the lubrication-free operation. Thus, the reliability of the low-stage compressor 10 is not reduced.

Therefore, the low-stage compressor 10 does not draw in the liquid refrigerant, and a highly reliable refrigerator-freezer can be provided.

(Embodiment 6) FIG. 6 is a cooling system diagram of a refrigerator-freezer according to Embodiment 6 of the present invention. In FIG. 6, reference numeral 23 denotes a high-stage flow control device 17 and a high-stage evaporator 9. A high-stage second capillary which is provided between and is in close contact with the low-stage evaporator 8.
High capacity second capillary 23 when the capacity of
This is a high-stage switching valve through which a refrigerant flows.

The operation of the refrigerator having the above-described structure will be described below. During normal operation, the refrigerant flowing through the high-stage flow control device 17 flows from the high-stage capillary 7 through the high-stage evaporator 9 and is sucked into the high-stage compressor 12.

Here, when the load in the freezing compartment becomes small and the refrigerating capacity of the low-stage evaporator 8 becomes excessive, the refrigerant flows through the high-stage second capillary 23 by the high-stage switching valve 24. Since the high-stage second capillary 23 exchanges heat with the low-stage evaporator 8, the excess refrigerating capacity of the low-stage evaporator 8 is used for cooling the high-stage second capillary 23, and accordingly, The high-stage second capillary 23 has a small degree of dryness even at the same reduced pressure, the refrigerating effect increases, and the refrigerating capacity of the high-stage evaporator 9 increases.

Thus, the refrigerating capacity of the high-stage evaporator 9 can be increased without unnecessary cooling of the freezing room.

Therefore, by increasing the refrigerating capacity of the high-stage evaporator 9, a high-efficiency refrigerator-freezer can be obtained.

(Embodiment 7) FIG. 7 is a cooling system diagram of a refrigerator-freezer according to Embodiment 7 of the present invention. In FIG. 7, reference numeral 25 denotes a low-stage flow control device 16 and a low-stage evaporator 8. A low-stage second capillary, which is provided between the low-stage capillary and the high-stage suction pipe 13 and is normally in contact with the high-stage suction tube 13. When the capacity becomes excessive, the lower stage second capillary 2
5 is a low-stage-side switching valve for flowing a refrigerant.

The operation of the refrigerator having the above-described structure will be described below. During normal operation, the refrigerant flowing through the low-stage flow control device 16 flows from the low-stage capillary 6 through the low-stage evaporator 8 and is sucked into the low-stage compressor 10.

Here, when the load in the refrigerator compartment becomes small and the refrigerating capacity of the high-stage evaporator 9 becomes excessive, the liquid refrigerant cannot be completely vaporized in the high-stage evaporator 9 and The liquid refrigerant also flows. At this time, the low-stage second capillary 25 exchanges heat with the high-stage suction pipe 13 by the low-stage switching valve 26, the liquid refrigerant in the high-stage suction pipe 13 is deprived of heat and vaporized, and the liquid refrigerant becomes high. It is not sucked into the stage compressor 12.

As a result, the excess liquid refrigerant of the high-stage evaporator 9 is sucked into the high-stage compressor 12, and the high-stage compressor 12 is broken by the liquid compression operation, and the sliding portion is worn by the non-lubricating operation. For example, the reliability of the high-stage compressor 12 is not reduced.

Therefore, the high-stage side evaporator 12 does not draw in the liquid refrigerant, and a highly reliable refrigerator-freezer can be obtained.

(Eighth Embodiment) FIG. 8 is a cooling system diagram of a refrigerator-freezer according to an eighth embodiment of the present invention. In FIG. 8, reference numeral 27 denotes a low-stage flow control device 16 and a low-stage evaporator 8. A low-stage second capillary 28 is provided between the high-stage evaporator 9 and is in close contact with the high-stage evaporator 9.
When the capacity of the system becomes excessive, the lower stage second capillary 27
This is a low-stage switching valve through which a refrigerant flows.

The operation of the refrigerator having the above-described structure will be described below. During normal operation, the refrigerant flowing through the low-stage flow control device 16 flows from the low-stage capillary 6 through the low-stage evaporator 8 and is sucked into the low-stage compressor 10.

Here, when the load of the refrigerator compartment becomes small and the refrigerating capacity of the high-stage evaporator 9 becomes excessive, the refrigerant flows through the low-stage second capillary 27 by the low-stage switching valve 28. Since the low-stage second capillary 27 exchanges heat with the high-stage evaporator 9, the excess refrigerating capacity of the high-stage evaporator 9 is used for cooling the low-stage second capillary 27, and accordingly, The low-stage-side second capillary 27 has a small degree of dryness even at the same reduced pressure, increases the refrigerating effect, and increases the refrigerating capacity of the low-stage-side evaporator 8.

Thus, the refrigeration capacity of the low-stage evaporator 8 can be increased without unnecessary cooling of the refrigerator compartment.

Therefore, a high-efficiency refrigerator-freezer can be provided by increasing the refrigerating capacity of the low-stage evaporator 8.

(Embodiment 9) FIG. 9 is a cooling system diagram of a refrigerator according to a ninth embodiment of the present invention. In FIG. 9, reference numeral 29 denotes a portion between the low-stage compressor 10 and the high-stage compressor 12. Is a low-stage second discharge pipe which is provided in close contact with the high-stage evaporator 9, and normally, the refrigerant discharged from the low-stage compressor 10 flows through the high-stage compressor 12 as it is, and This is a low-stage discharge switching valve that allows the refrigerant to flow through the low-stage second discharge pipe 29 when the load is small and the capacity of the high-stage evaporator 9 becomes excessive.

The operation of the refrigerator having the above-described configuration will be described below. During normal operation, the refrigerant discharged from the low-stage compressor 10 is directly
Sucked into.

Here, when the refrigerating room load is reduced and the refrigerating capacity of the high-stage evaporator 9 becomes excessive, the refrigerant flows through the low-stage second discharge pipe 29 by the low-stage discharge switching valve 30.
Since the low-stage second discharge pipe 29 exchanges heat with the high-stage evaporator 9, the excess refrigerating capacity of the high-stage evaporator 9 is used for cooling the low-stage second discharge pipe 29, Higher stage compressor 1
2, the suction gas temperature decreases, the suction specific volume increases, and the refrigerant circulation amount increases, so that the high-stage compressor 1
2 improves the efficiency.

Thus, the efficiency of the high-stage compressor 12 can be improved without unnecessary cooling of the refrigerator compartment.

Therefore, a high-efficiency refrigerator-freezer can be provided by improving the efficiency of the high-stage compressor 12.

(Embodiment 10) FIG. 10 is a cooling system diagram of a refrigerator-freezer according to Embodiment 10 of the present invention.
In FIG. 10, reference numeral 31 denotes a low-stage third discharge pipe provided between the low-stage compressor 10 and the high-stage compressor 12 and in close contact with the low-stage evaporator 8; The refrigerant discharged from the compressor 10 flows to the high-stage compressor 12 as it is, and when the freezer compartment load is small and the capacity of the low-stage evaporator 8 becomes excessive, the refrigerant is discharged to the low-stage third discharge pipe 31. This is a low-stage discharge switching valve for flowing.

The operation of the refrigerator having the above-described structure will be described below. During normal operation, the refrigerant discharged from the low-stage compressor 10 is directly
Sucked into.

Here, when the load of the freezing compartment becomes small and the refrigerating capacity of the low-stage evaporator 8 becomes excessive, the refrigerant flows through the low-stage third discharge pipe 31 by the low-stage discharge switching valve 32.
Since the low-stage third discharge pipe 31 exchanges heat with the low-stage evaporator 8, the excess refrigerating capacity of the low-stage evaporator 8 is used for cooling the low-stage third discharge pipe 31, Higher stage compressor 1
2, the suction gas temperature decreases, the suction specific volume increases, and the refrigerant circulation amount increases, so that the high-stage compressor 1
2 improves the efficiency.

Thus, the efficiency of the high-stage compressor 12 can be improved without unnecessary cooling of the refrigerator compartment.

Therefore, a high-efficiency refrigerator-freezer can be provided by improving the efficiency of the high-stage compressor 12.

(Embodiment 11) FIG. 11 is a cooling system diagram of a refrigerator-freezer according to Embodiment 11 of the present invention.
In FIG. 11, 33 is provided between the high-stage compressor 12 and the high-stage flow control device 17 and the low-stage flow control device 16,
A second condenser 34 is in close contact with the high-stage evaporator 9, and the refrigerant 34 normally flows through the condenser 5 directly to the low-stage flow control device 16 and the high-stage flow control device 17. This is a defrost valve that allows the refrigerant to flow to the second condenser during the defrosting operation of the evaporator 9.

The operation of the refrigerator having the above-described configuration will be described below. During normal operation, the refrigerant flowing through the condenser 5 flows directly to the low-stage flow control device 16 and the high-stage flow control device 17.

Here, if the cooling operation is continued for a certain period of time, a defrosting operation is performed to dissolve the frost adhering to the high-stage evaporator 9. At the time of the defrosting operation, the refrigerant stops flowing to the high-stage capillary 7 by the high-stage flow control device 17 and the cooling effect of the high-stage evaporator 9 is lost, and the refrigerant flowing through the condenser 5 by the defrost valve 34 After flowing through the second condenser 33, it flows to the low-stage flow control device 16 and the high-stage flow control device 17. At this time, about 40 ° C. was applied to the second condenser 33 closely contacting the high-stage evaporator 9.
Since the high-temperature refrigerant flows, the frost attached to the high-stage evaporator 9 is melted by heat.

Further, since the second condenser 33 is cooled by the frost, the supercooling is increased, the refrigerating effect is increased, and the refrigerating capacity on both the high stage side and the low stage side is increased.

As a result, the conventionally used defrosting means such as a heater becomes unnecessary, and the power consumption of the defrosting operation can be reduced, and the refrigerating capacity can be further increased.

Therefore, by reducing the power consumption during the defrosting operation of the high-stage evaporator 9 and increasing the refrigerating capacity, a highly efficient refrigerator-freezer can be obtained.

In this embodiment, the second condenser 3
Although the configuration 3 is described as being provided on the downstream side of the condenser 5, the same effect can be obtained if at least a part of the condenser 5 is in close contact with the high-stage evaporator 9. In this case, the condenser 5
The effect of defrosting is higher when it is in close contact with the high-stage evaporator 9 on the upstream side of the above.

(Embodiment 12) FIG. 12 is a cooling system diagram of a refrigerator according to a twelfth embodiment of the present invention.
In FIG. 12, 35 is provided between the high-stage compressor 12 and the high-stage flow control device 17 and the low-stage flow control device 16,
A third condenser 36 is in close contact with the low-stage evaporator 8, and normally 36 flows the refrigerant flowing through the condenser 5 as it is into the low-stage flow control device 16 and the high-stage flow control device 17. This is a defrost valve that allows the refrigerant to flow to the third condenser during the defrosting operation of the evaporator 8.

The operation of the refrigerator having the above-described structure will be described below. During normal operation, the refrigerant flowing through the condenser 5 flows directly to the low-stage flow control device 16 and the high-stage flow control device 17.

Here, if the cooling operation is continued for a certain period of time, a defrosting operation is performed to dissolve frost adhering to the low-stage evaporator 8. During the defrosting operation, the refrigerant stops flowing to the low-stage capillary 6 by the low-stage flow controller 16, the low-stage compressor 10 stops, and the cooling effect of the low-stage evaporator 8 is lost.
The refrigerant flowing through the condenser 5 by the defrost valve 36 is supplied to the third condenser 3
After flowing through No. 5, it flows to the low-stage flow control device 16 and the high-stage flow control device 17. At this time, since a high-temperature refrigerant of about 40 ° C. is flowing through the third condenser 35 which is in close contact with the low-stage evaporator 8, the frost attached to the low-stage evaporator 8 is melted by heat.

Further, when the third condenser 35 is cooled by the frost, the supercooling is increased, the refrigerating effect is increased, and the refrigerating capacity on both the high stage side and the low stage side is increased.

As a result, the conventionally used defrosting means such as a heater becomes unnecessary, so that the power consumption of the defrosting operation can be reduced and the refrigerating capacity can be further increased.

Therefore, the power consumption can be reduced during the defrosting operation of the low-stage side evaporator 8 and the refrigerating capacity can be increased, whereby a highly efficient refrigerator-freezer can be obtained.

In this embodiment, the third condenser 3
Although the configuration 5 is described as being provided on the downstream side of the condenser 5, the same effect can be obtained if at least a part of the condenser 5 is in close contact with the low-stage evaporator 8. In this case, the condenser 5
The defrosting effect is higher when it is in close contact with the low-stage evaporator 8 on the upstream side of the above.

[0124]

As described above, according to the present invention, the freezing room,
Even if one of the refrigerator compartments is running out of capacity,
By adjusting the flow rates of the refrigerant on the high stage side and the low stage side, the refrigeration capacity ratio of each room can be adjusted, and there is no needless operation in which the refrigeration capacity of the other room becomes excessive. Therefore, it is possible to prevent the efficiency from being lowered due to the load fluctuation, and it is possible to provide a highly efficient refrigerator-freezer.

Further, when either one of the freezing room and the refrigerator room becomes insufficient in capacity and the other room reaches the target temperature, the refrigerant is supplied to the evaporator for cooling the room reaching the target temperature. By not flowing, there is no needless operation for further cooling the room. Therefore, it is possible to prevent a decrease in efficiency due to a load change, and it is possible to obtain a more efficient refrigerator-freezer.

Further, the cooling capacity of the high-stage side evaporator can be increased by cooling the high-stage side capillary without wasting the outside air by the high-stage side suction pipe. Therefore, an increase in the refrigerating capacity of the high-stage side evaporator can provide a high-efficiency refrigerator-freezer.

In addition, by cooling the low-stage capillary without wasting the outside air with the low-stage suction pipe, the refrigerating capacity of the low-stage evaporator can be increased. Therefore, an increase in the refrigerating capacity of the low-stage side evaporator can provide a more efficient refrigerating refrigerator.

When the capacity of the low-stage evaporator is excessive, heat exchange between the low-stage suction pipe and the high-stage second capillary allows excess liquid refrigerant in the low-stage evaporator to be compressed by the low-stage compression. It is not sucked into the compressor and does not reduce the reliability of the low-stage compressor. Therefore, the low-stage compressor does not draw in the liquid refrigerant, and a highly reliable refrigerator-freezer can be provided.

Further, when the capacity of the low-stage evaporator is excessive, the low-stage evaporator and the high-stage second capillary are heat-exchanged, so that the freezing chamber is not cooled unnecessarily. The refrigeration capacity can be increased. Therefore, an increase in the refrigerating capacity of the high-stage side evaporator can provide a high-efficiency refrigerator-freezer.

When the capacity of the high-stage evaporator is excessive, heat exchange between the high-stage suction pipe and the low-stage second capillary allows excess liquid refrigerant in the high-stage evaporator to be compressed by the high-stage compression. It is not sucked into the compressor and does not reduce the reliability of the high-stage compressor. Therefore, the high-stage compressor does not draw in the liquid refrigerant, and a highly reliable refrigerator-freezer can be provided.

Further, when the capacity of the high-stage evaporator is excessive, heat exchange is performed between the high-stage evaporator and the low-stage second capillary, so that the low-stage evaporator can be cooled without useless cooling. The refrigeration capacity can be increased. Therefore, an increase in the refrigerating capacity of the low-stage evaporator can provide a high-efficiency refrigerator-freezer.

Further, when the capacity of the high-stage evaporator is excessive, heat exchange is performed between the high-stage evaporator and the low-stage second discharge pipe, and the temperature of the suction gas of the high-stage compressor is reduced, thereby refrigeration. The efficiency of the high-stage compressor can be improved without unnecessary cooling of the chamber. Therefore, a high-efficiency refrigerator-freezer can be obtained by improving the efficiency of the high-stage compressor.

When the capacity of the low-stage evaporator is excessive, heat exchange is performed between the low-stage evaporator and the low-stage third discharge pipe to reduce the suction gas temperature of the high-stage compressor. The efficiency of the high-stage compressor can be improved without unnecessary cooling of the chamber. Therefore, a high-efficiency refrigerator-freezer can be obtained by improving the efficiency of the high-stage compressor.

Further, during the defrosting operation, the high-stage side evaporator and the second condenser are exchanged with each other to dissolve the frost by the heat of the second condenser, so that the conventionally used defrosting means such as a heater is unnecessary. Thus, the power consumption of the defrosting operation can be reduced, and the refrigeration capacity can be further increased. Therefore, the power consumption can be reduced during the defrosting operation of the high-stage evaporator, and the refrigerating capacity can be increased.

Further, during the defrosting operation, the low-stage side evaporator and the second condenser exchange heat with each other to defrost the frost by the heat of the third condenser, so that the conventionally used defrosting means such as a heater is unnecessary. Thus, the power consumption of the defrosting operation can be reduced, and the refrigeration capacity can be further increased. Therefore, the power consumption can be reduced during the defrosting operation of the low-stage evaporator, and the refrigerating capacity can be increased, so that a highly efficient refrigerator-freezer can be provided.

[Brief description of the drawings]

FIG. 1 is a refrigeration system diagram of a refrigerator according to a first embodiment of the present invention.

FIG. 2 is a refrigeration system diagram of a refrigerator-freezer according to a second embodiment of the present invention.

FIG. 3 is a refrigeration system diagram of a refrigerator-freezer according to a third embodiment of the present invention.

FIG. 4 is a refrigeration system diagram of a refrigerator-freezer according to a fourth embodiment of the present invention.

FIG. 5 is a refrigeration system diagram of a refrigerator-freezer according to a fifth embodiment of the present invention.

FIG. 6 is a refrigeration system diagram of a refrigerator-freezer according to a sixth embodiment of the present invention.

FIG. 7 is a refrigeration system diagram of a refrigerator-freezer according to a seventh embodiment of the present invention.

FIG. 8 is a refrigeration system diagram of a refrigerator according to an eighth embodiment of the present invention.

FIG. 9 is a refrigeration system diagram of a refrigerator-freezer according to a ninth embodiment of the present invention.

FIG. 10 is a refrigeration system diagram of a refrigerator-freezer according to a tenth embodiment of the present invention.

FIG. 11 is a refrigeration system diagram of a refrigerator-freezer according to an eleventh embodiment of the present invention.

FIG. 12 is a refrigeration system diagram of a refrigerator-freezer according to a twelfth embodiment of the present invention.

FIG. 13 is a front view of an evaporator of a conventional refrigerator-freezer.

[Explanation of symbols]

 5 Condenser 6,20 Low-stage capillary 7,19 High-stage capillary 8 Low-stage evaporator 9 High-stage evaporator 10 Low-stage compressor 11 Low-stage suction pipe 12 High-stage compressor 13 High-stage Side suction pipe 14, 16 Low-stage flow controller 15, 17 High-stage flow controller 18 Check valve 21, 23 High-stage second capillary 22, 24 High-stage switching valve 25, 27 Low-stage second Capillaries 26, 28 Low-stage switching valve 29 Low-stage second discharge pipe 30, 32 Low-stage discharge switching valve 31 Low-stage third discharge pipe 33 Second condenser 34, 36 Defrosting valve 35 Third condenser

Claims (12)

[Claims] 1. A refrigerator-freezer body having a freezer compartment and a refrigerator compartment, a low-stage compressor, a high-stage compressor, a condenser, a low-stage capillary, the condenser and the low-stage capillary. A low-stage-side flow controller that adjusts the flow rate of refrigerant to the low-stage capillary, a low-stage evaporator that cools the freezing chamber, the low-stage evaporator, and the low-stage compressor A low-stage suction pipe, a high-stage capillary, and a high-stage flow controller that is provided between the condenser and the high-stage capillary and adjusts a refrigerant flow rate to the high-stage capillary. A refrigerator comprising a high-stage evaporator for cooling the refrigerator compartment, and a high-stage suction pipe provided between the high-stage evaporator and the high-stage compressor. 2. The refrigerator according to claim 1, wherein a check valve is provided on the high-stage suction pipe, and an operation of stopping the refrigerant is added to the low-stage flow control device and the high-stage flow control device. 3. The refrigerator according to claim 1, wherein the high-stage capillary is closely attached to the high-stage suction pipe. 4. The refrigerator according to claim 3, wherein the low-stage capillary is closely attached to the low-stage suction pipe. 5. A high-stage second capillary which is provided between the high-stage flow control device and the high-stage evaporator and is in close contact with the low-stage suction pipe, and the refrigerant which has exited the condenser is usually subjected to the high-stage The refrigerating refrigerator according to claim 4, further comprising a high-stage switching valve that flows into the high-side second capillary when the load in the freezing compartment is small and the capacity of the low-stage side evaporator becomes excessive. 6. A high-stage second capillary provided between the high-stage flow control device and the high-stage evaporator and in close contact with the low-stage evaporator; The refrigerating refrigerator according to claim 4, further comprising a high-stage switching valve that flows to the high-side second capillary when the load in the freezing compartment is small and the capacity of the low-stage evaporator becomes excessive. 7. A low-stage second capillary which is provided between the low-stage flow control device and the low-stage evaporator and is in close contact with the high-stage suction pipe; 5. The refrigerator according to claim 4, further comprising a low-stage switching valve that flows into the second capillary when the load in the refrigerator is small and the capacity of the high-stage evaporator becomes excessive. 8. A low-stage second capillary which is provided between the low-stage flow controller and the low-stage evaporator and is in close contact with the high-stage evaporator, and a refrigerant which has exited the condenser. 5. The refrigerator according to claim 4, further comprising a low-stage switching valve that flows into the low-stage second capillary when the load in the refrigerator is small and the capacity of the high-stage evaporator becomes excessive. 9. A discharge pipe provided between a low-stage compressor and a high-stage compressor, and a discharge pipe provided between the low-stage compressor and the high-stage compressor, and in close contact with a high-stage evaporator. A low-stage second discharge pipe,
The refrigerant discharged from the low-stage compressor is normally passed through the discharge pipe to the high-stage compressor, and when the load of the refrigerator compartment is small and the capacity of the high-stage evaporator becomes excessive, the low-stage The refrigerator according to any one of claims 1 to 8, further comprising a low-stage discharge switching valve that flows into the second discharge pipe. 10. A discharge pipe provided between a low-stage compressor and a high-stage compressor, and a discharge pipe provided between the low-stage compressor and the high-stage compressor, and in close contact with a low-stage evaporator. The low-stage third discharge pipe, and the refrigerant discharged from the low-stage compressor, usually flows to the high-stage compressor through the discharge pipe, the freezing compartment load is small, the low-stage evaporator 10. The refrigerator according to claim 9, further comprising a low-stage discharge switching valve that flows through the low-stage third discharge pipe when the capacity of the refrigerator becomes excessive. 11. A second condenser provided between the high-stage compressor and the high-stage flow control device and the low-stage flow control device and closely attached to the high-stage evaporator, and discharged from the high-stage compressor. The cooled refrigerant is passed through the high-stage flow control device and the low-stage flow control device normally only through a condenser, and the condenser is used during a defrosting operation to dissolve frost attached to the high-stage evaporator. The refrigerator according to any one of claims 1 to 10, further comprising a defrost valve that flows through the second condenser and the high-stage flow control device and the low-stage flow control device. 12. A third condenser which is provided between the high-stage compressor and the high-stage flow control device and the low-stage flow control device and is in close contact with the low-stage evaporator, and discharges from the high-stage compressor. The cooled refrigerant is usually passed only through a condenser to the high-stage flow control device and the low-stage flow control device, and the condenser is used during a defrosting operation in which frost attached to the low-stage evaporator is released. The refrigerator-freezer according to claim 11, further comprising: a defrost valve that flows through the third condenser to the high-stage flow control device and the low-stage flow control device.