JPH11142044A - Multiple refrigerator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable highly efficient operation without increasing the sealing quantity of a refrigerant during the closing operation of any one of open/close valves selected. SOLUTION: This refrigerator is provided with a plurality of refrigerator cabinets 13 and 15 constituting a refrigerating cycle in which a refrigerant delivered from a compressor 3 with the number of revolutions thereof controllable passes through a condenser 7 by way of a refrigerant piping 9 to be branched off a branch path 11 and then, through at least a dew prevention pipe 25, capillary tubes 19 and 27 and evaporators 23 and 31 to be returned to the compressor 3 again. On the other hand, open/close valves 33 and 35, openable or closable, for selecting the inflow of the refrigerant to the respective refrigerator cabinets 13 and 15 are installed respectively on the downstream side of the branch path 11 of the refrigerant piping 9 and on the upstream side of the dew prevention pipes 17 and 25 of the respective refrigerator cabinet 15 to shut down the inflow of the refrigerant to the side of the refrigerator cabinet where a valve is closed during the closing operation of one of the open/ close valves 33 and 35.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi refrigerator having a plurality of refrigerator cabinets.

[0002]

2. Description of the Related Art Generally, in a multi refrigerator, for example, a refrigerant is discharged from a compressor 103 arranged in a machine room 101 as shown in FIG. 5, and the discharged refrigerant passes through a condenser 105, It has a structure provided with a plurality of refrigerator cabinets 115 constituting a refrigeration cycle that branches off from the branch path 107, passes through the dew-proof pipe 109, the capillary tube 111, the evaporator 113, and returns to the compressor 103 again.

[0003]

The refrigerant flows in the dew-proof pipe 109 of each refrigerator cabinet 115 during operation in a gas-liquid two-phase flow state. At this time, for example, when the cooling on the left side of the drawing is temporarily stopped by the on-off valve 117 in a state where both refrigerator cabinets 115 are sufficiently cooled, the refrigerator cabinet 115 is cooled, so that the gas-liquid In the phase flow, the gas refrigerant liquefies sequentially on the spot.

When liquefied, the volume occupied in the dew prevention pipe 109 is reduced. It flows into the dew pipe 109. The gas portion of the gas-liquid two-phase refrigerant that has flowed in is similarly liquefied. As a result, the liquid refrigerant stays in the stopped dew-prevention pipe 109, resulting in a shortage of the refrigerant in the refrigeration cycle on the right side of the drawing during operation.

[0005] For this purpose, conventionally, measures such as providing a storage tank for increasing the amount of charged refrigerant have been adopted so that there is room even if part of the refrigerant is stored. Since the amount of refrigerant used increases, it is not desirable not only in terms of cost but also in terms of global environment.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a multi-refrigerator in which a proper amount of refrigerant is ensured in a refrigeration cycle during operation without increasing the amount of charged refrigerant.

[0007]

According to the present invention, a refrigerant discharged from a compressor passes through a condenser via a refrigerant pipe, branches off from a branch path, and is provided with at least a dew-proof pipe. In a multi-refrigerator having a plurality of refrigerator cabinets constituting a refrigerating cycle passing through a capillary tube and an evaporator and returning to a compressor again, an openable / closable valve for selecting a refrigerant flow into each refrigerator cabinet is provided.
It is provided downstream of the branch path of the refrigerant pipe and upstream of the dew-proof pipe of each refrigerator cabinet.

According to such a multi-refrigerator, the refrigerant discharged from the compressor passes through the dew-proof pipe, the capillary tube, and the evaporator through the branch path, and forms a refrigeration cycle that returns to the compressor again. The cooling state of the refrigerator cabinet is obtained. During this operation, when the inside of one refrigerator cabinet is sufficiently cooled, the on-off valve on the refrigerator cabinet side is closed to stop the flow of the refrigerant. At this time, of the gas-liquid two-phase refrigerant existing in the cold dew-proof pipe, the gas refrigerant is sequentially liquefied on the spot. At the time of this liquefaction, in the conventional refrigerator, the volume occupied in the dew prevention pipe is reduced, and the gas-liquid two-phase refrigerant during operation is attracted by the reduced volume. Since the passage is shut off by the on-off valve provided on the upstream side during the closing operation, the refrigerant does not flow into the dew-proof pipe on the stop side.

Therefore, the flow rate of the refrigerant constituting the refrigeration cycle during operation can be appropriately secured.

On the other hand, if the rotation speed of the compressor or the rotation speed of the condenser fan is reduced immediately after the refrigeration cabinet on one side is stopped, the cooling capacity is temporarily reduced.
This is because, immediately after one of the on-off valves is closed in this configuration, the liquid refrigerant still exists on the downstream side (that is, the dew-proof pipe and the evaporator). The compressor continues to collect refrigerant from both cabinets until the on-off valve is closed to stop the flow of refrigerant and until the depletion prevention pipe in the stop cabinet and the liquid refrigerant in the evaporator are depleted. Therefore, if the rotation speed of the compressor or the rotation speed of the condenser fan is reduced immediately after the one side is stopped, the refrigerant circulation amount in both cabinets is temporarily reduced.

Therefore, in the present invention, the rotation speed of the compressor and the air volume of the fan for the condenser are reduced with a predetermined time delay after the opening operation of the selected on-off valve.

Thus, when the on-off valve is closed, the rotational speed of the compressor and the air flow of the condenser fan are maintained as they are, and the amount of the refrigerant remaining in the stopped refrigeration cycle is reduced. Since the rotation speed and the fan air volume are reduced, a temporary decrease in the refrigerant flow rate and a decrease in the efficiency of the condenser are avoided.

Alternatively, after the closing operation of the selected on-off valve,
When the pressure detection means provided in the low pressure side refrigerant pipe detects a pressure value lower than a predetermined value, the rotation speed of the compressor and the air volume of the fan for the condenser may be reduced.

Alternatively, after the closing operation of the selected on-off valve,
When the temperature detecting means for detecting the evaporator outlet temperature detects a temperature value lower than a predetermined value, the rotational speed of the compressor and the air volume of the fan for the condenser may be reduced.

Alternatively, after the closing operation of the selected on-off valve,
When the temperature detecting means for detecting the evaporator outlet temperature detects a temperature lower than a predetermined value, and then detects that the temperature value has turned to an increase again, the rotational speed of the compressor and the air flow of the condenser fan are reduced. You may make it do.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a first embodiment of the present invention will be specifically described with reference to the drawing of FIG.

FIG. 1 shows a circuit diagram of a multi-refrigerator. In a machine room 1, a compressor 3 whose rotation speed can be controlled, a fan 5 for a condenser whose flow rate can be controlled, and a wind generated by the fan 5 And a condenser 7 to be cooled. The refrigerant discharged from the compressor 3 passes through the condenser 7 and passes through a branch 11 provided in the middle of the refrigerant pipe 9, one of which is on the first refrigerator cabinet 13 side and the other is on the second refrigerator cabinet 15. Each side is branched. One of the refrigerants branched via the branch path 11 passes through the dew-proof pipe 17, the capillary tube 19, the electronic expansion valve 21, and the evaporator 23 arranged in the first refrigerator cabinet 13, and returns to the compressor 3 again. A refrigeration cycle is configured. The other refrigerant branched via the branch passage 11 passes through the dew-proof pipe 25, the capillary tube 27, the electronic expansion valve 29, and the evaporator 31 arranged in the second refrigerator cabinet 15, and then returns to the compressor 3 again. A refrigeration cycle returning to the above is configured.

First and second refrigerator cabinets 13 and 1
In the refrigerant pipe 9 of FIG.
A first on-off valve 33 that can be opened and closed on the upstream side of the dew-proof pipe 17 on the refrigerator cabinet 13 side is provided on the downstream side of the branch passage 11 and on the upstream side of the dew-proof pipe 25 on the second refrigerator cabinet 15 side. Are provided with second open / close valves 35 that can be opened / closed.

The rotation speed of the compressor 3 and the air flow of the condenser fan 5 are controlled by a control unit 37, and by closing one of the on-off valves 33, 35, the evaporator of the refrigerated cabinet during suspension is stopped. A predetermined amount of time (e.g.,
(3 minutes) The compressor 3 is operated while maintaining the rotation speed, and thereafter, the operation is controlled so as to reduce the rotation speed of the compressor 3 and the air volume of the fan 5.

The electronic expansion valves 21 and 29 control the flow rate of the refrigerant based on the measurement signal from the temperature sensor S of the evaporator, thereby minimizing the degree of superheat of the evaporators 23 and 31. This allows the operation to follow the load to be performed quickly.

In the multi refrigerator constructed as described above, when the first and second on-off valves 33 and 35 are respectively opened,
The refrigerant discharged from the compressor 3 passes through the condenser 7 and is branched via the branch path 11.

One of the refrigerants branched via the branch passage 11 is supplied to the dew-proof pipe 17 of the first refrigerator cabinet 13,
Capillary tube 19, electronic expansion valve 21, evaporator 23
Refrigeration cycle that returns to the compressor 3 again, and in the evaporator 23, the cold air that has undergone heat exchange is sent into the refrigerator and cooled.

Further, the other refrigerant branched via the branch passage 11 passes through the dew-proof pipe 25, the capillary tube 27, the electronic expansion valve 29, and the evaporator 31 of the second refrigerator cabinet 15, and then returns to the compressor 3 again. A refrigeration cycle is formed, and in the evaporator 31, the heat-exchanged cold air is sent into the refrigerator, and the refrigerator is cooled. During this operation, for example, when the inside of the first refrigerator cabinet 13 is sufficiently cooled, the first opening / closing valve 33 is closed to stop the flow of the refrigerant into the first refrigerator cabinet 13.
At this time, in the conventional multi-refrigerator, the gas refrigerant of the gas-liquid two-phase refrigerant existing in the cold dew-proof pipe 17 is sequentially liquefied on the spot.

Therefore, after the first on-off valve 33 is closed, the rotational speed of the compressor 3 is maintained while the refrigerant remaining in the evaporator 23 and the dew-proof pipe 17 is reduced. The operation is continued for a predetermined time (for example, 3 minutes), and after the predetermined time has elapsed, the rotation speed of the compressor 3 is reduced to reduce the refrigeration capacity so that the refrigeration capacity is reduced to about half of the refrigeration capacity. Good driving becomes possible. In addition, since it is necessary to continue the heat radiation in the condenser along with the operation of the compressor 3, the air volume of the condenser fan 5 is also reduced at the same time as the rotation speed of the compressor 3 is reduced.

FIG. 2 shows one of the open / close valves 33, 35.
2 shows a second embodiment in which the rotation speed of the compressor 3 and the air volume of the condenser fan 5 are reduced based on the detection result of the pressure value in the low-pressure region after the closing operation of FIG.

In the second embodiment, the compressor 3
A pressure gauge 39 serving as pressure detecting means is provided in the refrigerant pipe 9 in the low pressure region on the suction side of the pressure gauge 39. After the selected one of the first and second on-off valves 33 and 35 is closed, the pressure gauge 39 is opened. When a pressure value lower than a predetermined pressure value is detected, the operation of the compressor 3 is controlled so as to reduce the rotation speed of the compressor 3 and the air flow rate of the radiating fan 5.

That is, if the rotation speed of the compressor 3 is maintained after the closing operation of one of the opening / closing valves 33, 35, the pressure gradually decreases as the liquid refrigerant in the stopped cabinet decreases. , By monitoring its pressure value,
For example, it is possible to know the approximate remaining amount of the refrigerant on the first refrigerator cabinet 13 side during stoppage.

The other components are the same as those in FIG.
The same reference numerals are given and the detailed description is omitted.

Therefore, according to the second embodiment, when the first open / close valve 33 is closed by sufficient cooling during operation, for example, as in FIG. The flow of the refrigerant to the downstream side from the branch path 11 serving as the refrigerator cabinet 13 is blocked.

On the other hand, after the closing operation of the first opening / closing valve 33, the pressure value is monitored by the pressure gauge 39 and a predetermined pressure value (for example, when the refrigerant is R134a, the absolute value is 0.1 mm).
05Mpd), the compressor 3 detects
The operation is controlled so as to reduce the rotation speed of the fan and the air volume of the condenser fan 5. Thus, the capillary tube 27 and the electronic expansion valve 29 on the second refrigerator cabinet 15 side
As a result, it is possible to prevent the pressure loss from increasing and to operate efficiently with the refrigeration capacity lowered according to the load.

FIG. 3 shows one of the open / close valves 33, 35.
3 shows a third embodiment in which the rotation speed of the compressor 3 and the air volume of the condenser fan 5 are reduced based on the detection result of the evaporator outlet temperature after the closing operation of.

In the third embodiment, the evaporator 2
A thermometer 41 serving as a temperature detecting means for detecting an evaporator outlet temperature is provided in the outlet-side refrigerant pipes 9 of 3 and 31, and a closing operation of one of the selected first and second on-off valves 33 and 35 is performed. Thereafter, when the thermometer 41 detects a temperature value lower than a predetermined evaporator outlet temperature value, the operation is controlled so as to reduce the rotation speed of the compressor 3 and the air volume of the condenser fan 5.

That is, when the rotation speed of the compressor 3 is maintained during the closing operation of one of the on-off valves 33 and 35, the pressure on the low pressure side also gradually decreases. The decrease in the pressure means, for example, that the evaporation temperature in the gas-liquid two-phase refrigerant in the region of the saturated vapor line 43 shown in FIG. 4 also decreases, and the temperature in the place where the liquid refrigerant remains decreases. I do.

At this time, for example, during the closing operation of the first opening / closing valve 33, the supply of the refrigerant is shut off, and during the operation of the compressor 3, the amount of the refrigerant on the closing operation side decreases gradually, and The tail moves sequentially from the inlet side 23a of the dew-proof pipe 17, the capillary tube 19, and the evaporator 23 to the outlet side 23b. For this reason, in the evaporator 23, the inlet side dries first, and the downstream outlet side does not immediately dry. Therefore, by monitoring the outlet temperature here, the remaining amount of the refrigerant on the side of the first refrigerator cabinet 13 that is stopped can be known.

In the third embodiment, the compressor and the fan are controlled by detecting the temperature value lower than the predetermined value. However, the temperature value at which the evaporator outlet temperature is lower than the predetermined value is detected. The configuration may be such that the operation is controlled so as to reduce the rotation speed of the compressor 3 and the air flow of the condenser fan 5 in view of a subsequent temperature change.

In this configuration, the evaporator outlet temperature keeps decreasing with the pressure drop during the gas-liquid two-phase flow. But,
When the evaporator outlet continuously absorbs heat and moves from the gas-liquid two-phase flow to the gas phase region (from the inside of the saturated vapor line 43 in FIG. 4 to the right).
Is approaching the internal temperature (for example, −20 ° C.). Accordingly, the temperature here always has a lower limit inflection point in time, and by monitoring this inflection point, it becomes possible to perform operation control for reducing the rotation speed of the compressor 3 and the air flow of the condenser fan 5. .

The other components are the same as those shown in FIG. 1, and thus the same reference numerals are given and the detailed description is omitted.

Therefore, according to this configuration, during operation, for example, when the inside of the first refrigerated cabinet 13 is sufficiently cooled, the first opening / closing valve 33 is closed to perform the same operation as in FIG. The flow of the refrigerant to the upstream side from the branch path 11 that becomes the first refrigerator cabinet 13 is blocked.

On the other hand, after the closing operation of the first on-off valve 33, the evaporator outlet temperature value is monitored by the thermometer 41, and when the temperature value lower than the predetermined temperature value is detected, the rotational speed of the compressor 3 and The operation of the condenser fan 5 is controlled so as to reduce the air flow. As a result, efficient operation in which the refrigerating capacity is reduced according to the load can be performed.

In each of the above embodiments, the refrigerating capacity is reduced by lowering the rotational speed of the compressor 3, but the present invention is not limited to this. For example, a configuration in which the capacity of the compressor is reduced by a release mechanism is used. But it is applicable. Further, the branch passage 11 is provided in the refrigerated cabinet, but is not limited to this, and a configuration provided in the machine room 1 side is also applicable.

[0041]

As described above, according to the multi-refrigerator of the present invention, the capacity is reduced and the efficiency is reduced during the closing operation of one of the selected on-off valves without increasing the amount of charged refrigerant. Driving becomes possible.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of a multi refrigerator according to a first embodiment of the present invention.

FIG. 2 is a circuit diagram similar to FIG. 1 showing a second embodiment in which the rotation speed of the compressor and the air flow rate of the fan for the condenser are reduced by pressure detecting means.

FIG. 3 is a circuit diagram similar to FIG. 1 showing a third embodiment in which the rotation speed of the compressor and the air volume of the condenser fan are reduced by temperature detection means for detecting the evaporator outlet temperature.

FIG. 4 is a Mollier diagram.

FIG. 5 is a circuit diagram of a multi refrigerator according to a conventional example.

[Explanation of symbols]

 REFERENCE SIGNS LIST 3 Compressor 5 Fan for condenser 7 Condenser 9 Refrigerant pipe 11 Branch path 13, 15 Refrigerator cabinet 17, 25 Dew-proof pipe 19, 27 Capillary tube 23, 31 Evaporator 33, 35 Open / close valve

Claims (5)

[Claims] 1. A refrigeration cycle in which a refrigerant discharged from a compressor passes through a condenser via a refrigerant pipe, branches in a branch, passes through at least a dew-proof pipe, a capillary tube, and an evaporator, and returns to the compressor again. In a multi-refrigerator including a plurality of refrigerator cabinets, an open / close valve for selecting the flow of refrigerant into each refrigerator cabinet is provided at a position downstream of the branch line of the refrigerant pipe and upstream of the dew-proof pipe of each refrigerator cabinet. A multi-refrigerator characterized by being provided. 2. The multi-refrigerator according to claim 1, wherein a predetermined time delay is given after the closing operation of the selected on-off valve to reduce the rotation speed of the compressor and the air volume of the condenser fan. 3. After the closing operation of the selected on-off valve, when the pressure detecting means provided in the low pressure side refrigerant pipe detects a pressure value lower than a predetermined value, the rotational speed of the compressor and the fan of the condenser are detected. The multi refrigerator according to claim 1, wherein the air volume is reduced. 4. After the selected on-off valve is closed, when the temperature detecting means for detecting the evaporator outlet temperature detects a temperature value lower than a predetermined value, the rotational speed of the compressor and the air volume of the fan for the condenser are detected. The multi refrigerator according to claim 1, wherein the temperature is lowered. 5. After the selected on-off valve is closed, the temperature detecting means for detecting the evaporator outlet temperature detects a temperature value lower than a predetermined value and then detects that the temperature value has started to rise again. 2. The multi refrigerator according to claim 1, wherein the rotation speed of the compressor and the air volume of the condenser fan are reduced.