JPH06174342A - Refrigerator - Google Patents

Abstract

PURPOSE:To prevent the pressure of refrigerant sucked up into a refrigerant compressor from falling to a specific value or below and protect this refrigerant compressor from being subjected to the liquid back of the refrigerant, during defrosting. CONSTITUTION:A high pressure gas pipeline 24 which connects a refrigerant compressor 19 to a condenser 20 and a low pressure gas pipeline 27 which connects a vaporizer 5 to the refrigerant compressor 19, are connected with a capacity control circuit 38. This capacity control circuit 38 is designed to provided a capacity control valve 40 whose opening is controlled by the pressure of the refrigerant in the low gas pipeline 27 during defrosting operation of the vaporizer 5 and which leads a part of hot gas to the low pressure gas pipeline 27.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigerating apparatus used for a low temperature showcase, a refrigerator and an air conditioner.

[0002]

2. Description of the Related Art JP-A-57-67771 (F25
D21 / 06), an evaporator and a fan are housed in an inner and outer two-layer inner duct and an amta duct, which are independently formed between the outer box and the inner box of the case body, and both evaporators are attached together with a pressure reducing element. In parallel with connecting to the condensing unit, when viewed from the condensing unit, the decompression element of the upstream evaporator of the refrigeration cycle and the downstream evaporator are each connected in parallel with a bypass circuit with a bypass valve,
By switching the bypass valves alternately, the downstream evaporator is off-cycle defrosted during the cooling operation of the upstream evaporator, and the upstream evaporator is removed by the sensible heat of the liquid refrigerant during the cooling operation of the downstream evaporator. A refrigerated showcase characterized by being frosted is disclosed.

[0003]

SUMMARY OF THE INVENTION In the above conventional technique,
Since both the upstream and downstream evaporators are connected in series,
When the cooling operation is switched from the downstream side evaporator to the upstream side evaporator, a large amount of the residual liquid refrigerant in the upstream side evaporator returns to the compressor, and so-called liquid back may damage the compressor. Challenges arose.

Therefore, the present invention prevents the pressure of the refrigerant sucked into the refrigerant compressor from falling below a predetermined value during defrosting operation, and prevents the refrigerant from flowing back to the refrigerant compressor. The purpose is to do.

[0005]

In order to solve the above problems, the present invention has a capacity of a high pressure gas pipe connecting a refrigerant compressor and a condenser and a low pressure gas pipe connecting an evaporator and a refrigerant compressor. While connecting with the adjustment circuit, this capacitance adjustment circuit,
The opening / closing degree is adjusted by the pressure of the refrigerant in the low-pressure gas pipe during the defrosting operation of the evaporator, and a capacity adjusting valve for guiding a part of the hot gas in the high-pressure gas pipe to the low-pressure gas pipe when the refrigerant pressure decreases is provided. It was done.

[0006]

[Function] When the pressure of the refrigerant in the low pressure gas pipe is lowered during the defrosting operation of the evaporator, the opening / closing degree of the capacity adjusting valve is automatically adjusted according to the pressure drop, and a part of the hot gas in the high pressure gas pipe is adjusted. To the low-pressure gas pipe through the capacity adjustment circuit, to increase the refrigerant pressure of the low-pressure gas pipe, to give a so-called low-pressure compensation to maintain a predetermined pressure or more, and the refrigerant sucked into the refrigerant compressor It acts to gasify the liquid phase.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Reference numeral 1 shown in FIG. 9 is an open type low temperature showcase in which a main body is composed of a heat insulating wall 2 having an opening 3 for storing and taking out products on the front surface, which is more suitable than the inner wall of the heat insulating wall. Insulation provided with a first damper 4A which opens to the inner layer side described later with a space therebetween, a second damper 4B which opens to the outer layer side described later, and first and second both windows 4C and 4D which are respectively closed to these dampers Layer 7 for disposing a plate-fin type outer layer evaporator 5 and an axial flow type outer layer blower 6 by disposing the first partition plate 4 having heat resistance, and for the outer layer located along the upper edge of the opening. An outlet 8 and an outer-layer suction port 9 located along the lower edge of the opening and facing the outer-layer outlet are formed.
An inner layer 13 in which a second partition plate 10 made of metal is arranged at an appropriate distance from the inner wall of the partition plate, and a plate fin type inner layer evaporator 11 and an axial flow type inner layer blower 12 are arranged, An inner layer blow-out port 14 arranged in parallel at the upper edge of the opening and inside the outer layer blow-out port 8, and an outer layer suction port 9 at the lower edge of the opening.
A storage chamber 17 in which inner layer suction ports 15 that are arranged in parallel inward of the inner layer and face the inner layer outlets and a plurality of shelves 16 are arranged
And form. The first and second dampers are plate-shaped members made of a heat insulating material such as resin, and the first damper 4A is provided upstream of the second damper 4B in the flow direction of the circulating air and is open. When the tip is the second partition plate 10
It is preferable that the tip of the second damper 4B is in contact with or close to the inner wall of the heat insulating wall 2 when opened. The outer layer evaporator is arranged in the outer layer 5 so as to be located between the first and second dampers 4A and 4B, and the inner layer evaporator 11 is upstream from the first damper 4A in the flow direction of the circulating air. It is located in the side position.
Both the first and second dampers are simultaneously opened and closed by a single drive device M using a gear motor, a cylinder and the like.

Reference numeral 18 shown in FIG. 1 is a refrigerating apparatus for cooling the low-temperature showcase, which is an expansion valve provided with a refrigerant compressor 19, an air-cooled heat exchanger 20, a liquid receiver 21, and a temperature sensing section 22A. Pressure reducing valve 22, etc., evaporator 11 for inner layer, gas-liquid separator 2
3 is annularly connected by a high pressure gas pipe 24, a high pressure liquid pipe 25, a low pressure liquid pipe 26 and a low pressure gas pipe 27 to form a closed circuit. 28 is a check valve connected in parallel with the pressure reducing valve 22;
Reference numeral 9 is a first electromagnetic valve arranged in the high pressure liquid pipe 25 between the liquid receiver 21 and the pressure reducing valve 22, and 30 is arranged in the low pressure gas pipe 27 between the inner layer evaporator 11 and the gas-liquid separator 23. The second electromagnetic valve 31, which has been installed, has one end between the liquid receiver and the first electromagnetic valve 29,
The other end is a bypass circuit with a third electromagnetic valve 32, which is connected between the inner layer evaporator and the second electromagnetic valve 30 and is opened when the inner layer evaporator 11 is defrosted. Also, the outer layer evaporator 5
Are arranged in parallel with the inner layer evaporator 11, and are connected to the high pressure liquid pipe 25 and the low pressure liquid pipe 27 by the high pressure liquid branch pipe 33, the low pressure liquid branch pipe 34 and the low pressure gas branch pipe 35. 36
Is a motor-operated valve arranged in the high-pressure liquid branch pipe 33, which has a depressurizing function for depressurizing the liquid refrigerant and an opening / closing function for supplying and stopping the liquid refrigerant to the outer layer evaporator 5. A fourth solenoid valve 37 is connected in parallel to the motor-operated valve and is opened during a pump down operation described later. Reference numeral 38 denotes a capacity adjusting circuit having one end connected to the high pressure gas pipe 24 and the other end connected to the low pressure gas pipe 27. The fifth solenoid valve 39 is opened during the defrosting operation and the pump down operation, and the inside of the low pressure gas pipe 27. The capacity adjusting valve 40 is automatically opened / closed by the refrigerant pressure and its opening / closing degree is adjusted.

The above-described refrigerating apparatus 18 of FIG. 1 is an embodiment in which one or two low temperature showcases 1 are adapted. When a water-cooled condenser 20 is used, the embodiment is shown in FIG. . In this case, the temperature of the water with which the hot gas is heat-exchanged is
Since it does not change to the outside air temperature throughout the four seasons, the receiver 2
1 can be deleted. FIG. 3 shows an embodiment in which three or more low temperature showcases 1 are equipped with an air-cooling type refrigerating device 18. In this case, the high pressure liquid pipe 25 is opened during cooling operation and closed during defrosting operation and pump down operation. 6th solenoid valve 4
1 is provided, and one end of the high pressure liquid pipe 25 between the sixth solenoid valve 41 and each first solenoid valve 29 is connected to the high pressure gas pipe 2
4 is provided with a hot gas pipe 43 having the other end connected thereto and having a seventh solenoid valve 42 which is opened during the defrosting operation.

FIG. 4 shows an embodiment in which a water-cooling type refrigerating device 18 is used in three or more low temperature showcases 1. In this case as well, the liquid receiver 21 is deleted as in FIG. When a plurality of low-temperature showcases 1 are arranged in parallel to perform cooling, defrosting, and pump-down operations, it is preferable to synchronize each operation of the low-temperature showcases 1 in view of the circulating air flow.

Next, the operation of the low temperature showcase 1 will be described based on the refrigerating device 18 shown in FIG. Now, the first damper 4A and the second damper 4B are closed as shown by the solid line in FIG.
The inner layer 13 and the outer layer 7 are independent of each other. At this time, the first and second solenoid valves 29, 30 are open, and the third, fourth, fifth solenoid valves 32, 37, 39 and the motor-operated valve 36 are closed, and in such a state, When the refrigerant compressor 19 is operated, the refrigerant is compressed as shown by the arrow in FIG. 5: compressor 19-condenser 20-liquid receiver 21-solenoid valve 29-pressure reducing valve 22-inner layer evaporator 11
-Solenoid valve 30-Gas-liquid separator 23-Compressor 19 forms a well-known first cycle, during which the condenser 20 condenses and liquefies, the pressure reducing valve 22 decompresses, and the inner layer evaporator evaporates and vaporizes. In this cooling operation (for example, 4 hours), the circulating air passing through the inner layer 13 by the inner layer blower 12 is a low-pressure liquid refrigerant (for example, −10 ° C.) passing through the inner layer evaporator 11.
Evaporation temperature) and becomes cooling air at -4 ° C,
As shown by the arrow in FIG. 9, a cool air curtain (CA) is formed in the opening 3 to cool the storage chamber 17 at −2 ° C. During this time, the first and second solenoid valves 29, 30
Simultaneously opens and closes by the temperature detector of the storage chamber 17 to maintain the temperature of the storage chamber 17 at an appropriate temperature. On the other hand, the circulating air passing through the outer layer 7 by the outer layer blower 6 is cooled by the cold air curtain (C) at the opening 3 as shown by the arrow in FIG.
Flowing along the outside of A), the temperature of the cold air curtain (CA) becomes gradually lower than that of the outside air surrounding the low temperature showcase 1 under the influence of the cold air curtain.
Air curtain (GA) that prevents contact between the air and the outside air
Acts as.

With the progress of the cooling operation, the evaporator 11 for the inner layer
When the amount of frost on the motor-operated valve 36 increases, a part of the liquid refrigerant from the first electromagnetic valve 29 is diverted to the high-pressure liquid branch pipe 33. The divided liquid refrigerant is decompressed by the electric valve 36,
The vaporization in the outer layer evaporator 5 passes through the low pressure gas branch pipe 35, the low pressure gas pipe 27, the low pressure gas refrigerant that has passed through the inner layer evaporator 11 and the flow into the compressor 19. Form a second cycle. This second cycle is performed for several tens of seconds to several minutes before the end of the cooling operation, that is, immediately before switching from the cooling operation to the defrosting operation, and by this operation, like the inner layer evaporator 11, the outer layer evaporator 5 is
Becomes low temperature, the circulating air passing through the outer layer 7 is heat-exchanged with the low-pressure liquid refrigerant (evaporating temperature of −17 ° C.) passing through the outer layer evaporator 5, and the cooling air circulating through the inner layer 13 is almost the same. The same or slightly higher temperature, for example -2 ° C, is maintained.
In addition, in this cooling operation, the operation of the outer layer blower 6 may be stopped.

During this cooling operation, the defrosting start signal is output and both the first and second electromagnetic valves 29 and 30 are closed, and the third and fifth electromagnetic valves are closed.
Both solenoid valves 32, 39 are opened, and both the first and second dampers 4
When A and 4B are opened as shown by the chain line in FIG. 9, the operation is switched to the defrosting operation, and the liquid refrigerant from the liquid receiver 21 is bypass pipe 31-inner layer evaporator 11-check valve 28-fourth solenoid valve 37. -Motorized valve 36-Evaporator 5 for outer layer-Gas-liquid separator 23-Compressor 19 and part of the hot gas discharged from the refrigerant compressor 19 flows from the capacity adjusting circuit 38 to the low pressure gas pipe 27. Forming a third cycle of flowing arrows. This third cycle is, for example, a defrosting operation cycle of the inner layer evaporator 11 performed for 10 to 20 minutes, and the liquid refrigerant from the bypass pipe 31 is heat-exchanged in the inner layer evaporator 11 to become a supercooled liquid. Evaporator for inner layer 1 due to its sensible heat
Thaw the frost of 1. Further, in this defrost cycle, when the refrigerant pressure in the low pressure gas pipe 27 becomes lower than the predetermined pressure, the capacity adjusting valve 40 opens to guide the hot gas to the low pressure gas pipe 27 and raise the low pressure to the predetermined pressure. Thus, low pressure compensation is performed and the liquid phase contained in the low pressure refrigerant is evaporated by the sensible heat of the hot gas. On the other hand, the circulating air that has passed through the inner layer evaporator is interrupted in the flow in the inner layer 13 by the first damper 4A and flows from the first window 4C to the outer layer 7, and the low-pressure liquid refrigerant and the heat that are passing through the outer layer evaporator 5 It is replaced and cooled. The cooled circulating air is directed by the second damper 4B, returns from the second window 4D to the inner layer 13, and is blown from the inner layer outlet 14 toward the opening 3,
As in the cooling operation, a cold air curtain (CA) is formed, and the circulation of the chain line arrow in FIG. 9 for returning from the inner layer suction port 15 to the inner layer 13 is repeated.

The inner layer evaporator 11 along with the progress of the defrosting operation
When the frost has thawed, the third solenoid valve 32 closes while the first and second solenoid valves 29, 30 remain closed, and
When the fourth solenoid valve 37 is opened, the liquid refrigerant is not supplied to the inner layer evaporator 11, and a so-called pump that collects the residual liquid refrigerant (including a part of saturated gas) in the inner layer evaporator 11 into the liquid receiver 21. The down operation is performed, and the liquid refrigerant in the evaporator 11 for the inner layer is, as shown by the arrow in FIG. 7, a check valve 28-a fourth solenoid valve 37-an evaporator 5 for the outer layer-a gas-liquid separator 23-a compressor 19-a condenser. Two
0-flows with the liquid receiver 21 and is stored in the liquid receiver 21 as high-pressure liquid refrigerant. On the other hand, when the refrigerant pressure in the low-pressure gas pipe 27 is low, the capacity adjustment valve 40 is opened to raise the low-pressure force to a predetermined pressure as in the defrosting operation, and the liquid phase in the gas-liquid mixed refrigerant is hot. Evaporate with gas to prevent liquid back. This pump down operation is performed by the inner layer evaporator 11
Is performed for several minutes to several tens of minutes with the completion of the defrosting operation of the inner layer, and during this period, the saturated gas and the liquid refrigerant in the refrigerant in the inner layer evaporator 11 are sequentially sucked into the outer layer evaporator 5. A part of it is vaporized and vaporized in the evaporator 11 to give a cooling action to the inner layer evaporator 11 by this latent heat of vaporization, and the refrigerant flowing in the outer layer evaporator 5 up to the liquid refrigerant is evaporated in the outer layer. While passing through the vessel, it is vaporized and evaporated, and the latent heat of vaporization gives a cooling action to the outer layer evaporator 5. or,
This pump-down operation is also the time for draining dew attached to the inner layer evaporator 11. With the completion of the pump down operation, both the fourth and fifth electromagnetic valves 37, 39 are closed, the first and second electromagnetic valves 29, 30 are opened, and the cooling operation shown in FIG. 5 is restored.

Incidentally, the first, second and third cycles,
That is, the cooling operation of only the inner layer evaporator 11, the both cooling operations of both the inner layer and outer layer evaporators 11 and 5, the defrosting operation of the inner layer evaporator 11 (the outer layer evaporator 5 is in the cooling operation) and the pump down operation. The four operation modes A, B, C and D of FIG.
The same can be done with the refrigerating device 18 shown in FIG. The above four operation modes can be represented by the time chart shown in FIG.

Therefore, according to such a refrigerating device 18, since the solenoid valve 39 of the capacity adjusting circuit 38 is opened during the defrosting operation and the pump down operation, the low pressure gas refrigerant or the low pressure gas passing through the low pressure gas pipe 27 is reduced. When the pressure of a low-pressure refrigerant such as a gas-liquid mixed refrigerant falls below a predetermined pressure, the capacity adjusting valve 4
0 is opened by the pressure loss of the low pressure refrigerant, and the high pressure gas pipe 24
A part of the hot gas can be guided to the low pressure gas pipe 27 through the capacity adjusting circuit 38. As a result, the low pressure refrigerant returning from the low pressure gas pipe 27 to the refrigerant compressor 19 by the hot gas is increased to a predetermined pressure to compress the refrigerant. The operation of the machine 19 can be maintained in a good state, and when there is a liquid phase in the low-pressure refrigerant, it is evaporated to a gas phase, so that liquid back to the refrigerant compressor 19 can be prevented.

[0017]

As described above, according to the present invention, when the pressure of the refrigerant in the low pressure gas pipe connected to the refrigerant compressor is lowered during the defrosting operation, the capacity is automatically adjusted according to this pressure reduction. The valve is opened, and a part of the hot gas in the high-pressure gas pipe is guided to the low-pressure gas pipe through the capacity adjusting circuit, and low-pressure compensation can be performed to raise the low-pressure pressure to a predetermined pressure.

Therefore, it is possible to avoid the stop of the refrigerant compressor caused by the drop of the low pressure, to continuously operate the refrigerant compressor by following the load fluctuation, and to perform the stable defrosting operation which is not affected by the load fluctuation. Can be done. Further, during the defrosting operation, when the low-pressure refrigerant in the low-pressure gas pipe has a liquid phase, this is evaporated by the hot gas into the gas phase, so that liquid back to the refrigerant compressor can be prevented.

[Brief description of drawings]

FIG. 1 is a defrost cycle diagram of an air-cooled refrigeration system showing an embodiment of the present invention.

FIG. 2 is a circuit diagram of a main part when the refrigerating apparatus shown in FIG. 1 is changed to a water cooling type.

FIG. 3 is a circuit diagram of a main part when the refrigerating apparatus shown in FIG. 1 has multiple systems.

FIG. 4 is a circuit diagram of essential parts when the refrigerating apparatus shown in FIG. 3 is changed to a water cooling type.

FIG. 5 is a one-evaporator cooling cycle diagram in the refrigerating apparatus shown in FIG.

6 is a two-evaporator cooling cycle diagram in the refrigerating apparatus shown in FIG.

FIG. 7 is a cycle diagram during pump down operation in the refrigerating apparatus shown in FIG.

8 is a time chart showing each operation of the refrigerating apparatus shown in FIG.

FIG. 9 is a vertical cross-sectional view of a low temperature showcase incorporating the refrigeration system shown in FIG.

[Explanation of symbols]

 5 Evaporator 19 Refrigerant compressor 20 Condenser 22 Pressure reducing valve 24 High pressure gas pipe 25 High pressure liquid pipe 26 Low pressure liquid pipe 27 Low pressure gas pipe 38 Capacity adjustment circuit 40 Capacity adjustment valve

Claims (1)

[Claims] 1. A refrigerant compressor, a condenser, a pressure reducing valve, and an evaporator, wherein the refrigerant compressor and the condenser are high-pressure gas pipes, and the condenser and the pressure reducing valve are high-pressure liquid pipes. The pressure reducing valve and the evaporator are formed of a low pressure liquid pipe, and the evaporator and the refrigerant compressor are connected to each other by a low pressure gas pipe to form a refrigeration circuit capable of performing a cooling operation, and this cooling operation forms a frost on the evaporator. In the refrigerating apparatus for performing the defrosting operation in which the refrigerant in the high-pressure liquid pipe is introduced to the evaporator, the high-pressure gas pipe and the low-pressure gas pipe are connected by a capacity adjusting circuit, and the capacity adjusting circuit The opening and closing degree is adjusted by the pressure of the refrigerant in the low-pressure gas pipe during the defrosting operation, and a capacity adjustment valve for guiding a part of the hot gas in the high-pressure gas pipe to the low-pressure gas pipe when the pressure decreases A refrigerating device characterized by being provided.