JP2000337720A - Air conditioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform refrigerant recovery operation surely by providing a second variable pressure reducing mechanism between a gas/liquid separator and the suction part of a compressor. SOLUTION: The air conditioner comprises a first expansion valve 3 as a pressure reducing mechanism, a gas/liquid separator 4, and a fully closable variable pressure reduction expansion valve 8 as a second pressure reducing mechanism. Gas refrigerant separated by the gas/liquid separator 4 is returned back to a compressor 1 after pressure is reduced by the second expansion valve 8. When the refrigerating capacity is varied in correspondence with variation of thermal load by varying the r.p.m. of the compressor, pressure reduction of the second pressure reducing mechanism 8 is controlled because the operating pressure is varied. Refrigerant can be prevented from bypassing through the gas/liquid separator 4 by fully closing the second or first expansion valve 8, 3. Since refrigerant can be recovered surely from an indoor heat exchanger 6 and connection piping (5, 7), residual refrigerant can be prevented from being discharged the atmosphere and no additional refrigerant is required when an air conditioner is reinstalled.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a separation type air conditioner having an indoor unit and an outdoor unit.

[0002]

2. Description of the Related Art A conventional compressor, an outdoor heat exchanger, an outdoor unit having a decompression mechanism, and an indoor unit having an indoor heat exchanger are sequentially connected by piping, and a gas is interposed between the decompression mechanism and the indoor heat exchanger. A liquid separator is installed, the liquid refrigerant separated by the gas-liquid separator is connected so that the indoor heat exchanger and the gas refrigerant flow into the compressor suction part, and between the gas-liquid separator and the compressor suction part An air conditioner having a second pressure reducing mechanism in the flow path is provided with a capillary tube as a second pressure reducing mechanism in the flow path between the compressor suction portions as described in, for example, JP-A-9-145167. Was something.

[0003]

The object of the gas-liquid separator is to separate the gas-liquid two-phase refrigerant flowing out of the pressure reducing mechanism into a liquid and a gas by a gas-liquid separator provided on the downstream side of the pressure reducing mechanism.
Gas refrigerant with a large volume flow is passed through the compressor, and liquid refrigerant with a small volume flow is passed through the indoor heat exchanger (evaporator) to reduce refrigerant pressure loss in the indoor heat exchanger and connection pipes, thereby reducing electricity to the compressor. The purpose is to reduce the input and improve the efficiency of the refrigeration cycle.

When the separation type air conditioner is separated into an outdoor unit and an indoor unit, it is necessary to perform a refrigerant recovery operation for storing the refrigerant in the indoor heat exchanger and the connection pipe in the outdoor heat exchanger before separation. . This is to close the flow path on the upstream side of the indoor heat exchanger, reduce the suction pressure of the compressor, and recover the refrigerant in the indoor heat exchanger and the connection pipe to the outdoor unit.

However, when the gas-liquid separator is installed, even if the flow path on the upstream side of the indoor heat exchanger is closed, the refrigerant flows into the compressor suction portion via the bypass between the gas-liquid separator and the compressor suction portion. Since the refrigerant flows into the compressor, the suction pressure of the compressor does not decrease, refrigerant cannot be recovered, and the refrigerant not recovered from the indoor heat exchanger when the indoor / outdoor unit is separated is released to the atmosphere. There was a problem. In addition, the release of the refrigerant itself to the atmosphere is also a problem because it is a factor of depletion of the ozone layer and global warming.

In the case of an air conditioner capable of performing a heating operation by providing a four-way valve for switching the flow direction of refrigerant before and after the compressor, when an outdoor heat exchanger is frosted,
In order to melt the frost, there is a method of switching the four-way valve to flow a high-temperature refrigerant to the outdoor heat exchanger. .

[0007] An object of the present invention is to reliably perform a refrigerant recovery operation even when a gas-liquid separator is used in a separation type air conditioner. Another object is to prevent the room temperature during the defrosting operation from lowering.

[0008]

An air conditioner according to the present invention comprises a pipe, an outdoor unit having at least a compressor, an outdoor heat exchanger, a first pressure reducing mechanism, and an indoor unit having an indoor heat exchanger. A gas-liquid separator is installed between the first pressure reducing mechanism and the indoor heat exchanger, so that the liquid refrigerant separated by the gas-liquid separator flows into the indoor heat exchanger and the gas refrigerant flows into the compressor suction section. And a separation type air conditioner capable of separating the indoor / outdoor unit, wherein a variable pressure reduction type second pressure reduction mechanism is provided between the gas-liquid separator and the compressor suction section.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to FIG. In FIG. 1, 1 is a compressor, 2 is an outdoor heat exchanger, 3 is a first expansion valve as a pressure reducing mechanism, 4 is a gas-liquid separator, 5 is a first connection pipe, 6 is an indoor heat exchanger, 7 Denotes a second connection pipe, 8 denotes a fully-closable variable pressure reduction type expansion valve as a second pressure reducing mechanism, 9 denotes an outdoor blower fan, and 10 denotes an indoor blower fan. 11 is a first on-off valve, 12 is a second on-off valve, and 13 to 16 are first to fourth connectors. These are separated into an outdoor unit 17 composed of the compressor 1, the outdoor heat exchanger 2 and the like, and an indoor unit 18 composed of the indoor heat exchanger 6 and the like, the first connection pipe 5 and the second connection pipe. 7 to form an air conditioner.

The operation of the above air conditioner during the cooling operation will be described. The high-temperature and high-pressure gas refrigerant compressed by the compressor 1 releases heat to the air blown from the outdoor fan 9 in the outdoor heat exchanger 2 and condenses. It becomes a refrigerant and flows into the gas-liquid separator 4. In the gas-liquid separator 4, the liquid refrigerant stays downward and the gas refrigerant stays upward due to the density difference, and the liquid refrigerant flows out from below the gas-liquid separator and passes through the first connection pipe 5 through the indoor heat exchanger 6 to use 10
Absorbs heat from the air blown from the evaporator and evaporates.
Return to At this time, the gas refrigerant separated by the gas-liquid separator 4 is
The pressure is reduced by the second expansion valve 8 and returns to the compressor 1 again.

As described above, since the liquid refrigerant having a high density flows into the indoor heat exchanger 6, the pressure loss of the refrigerant in the indoor heat exchanger 6 and the second connection pipe 7 is reduced, and the compressor 1 Since the suction pressure also increases, the work amount of the compressor 1 is reduced, and the refrigeration cycle efficiency is improved.

When the cooling capacity is changed in response to the change in the heat load, the cooling speed is changed. However, in this case, since the operating pressure changes, the pressure reduction amount of the second pressure reducing mechanism 8 is controlled. There is a need. FIG. 3 shows the relationship between the compressor speed and the valve opening. The rotation speed of the compressor is determined by the difference between the actual room temperature and the set temperature. As a result, even if the required capacity changes, the opening degree of the second expansion valve can be set to the optimum state, so that the efficiency of the air conditioner using the gas-liquid separator can be improved in a wide range.

When the air conditioner is separated into an indoor unit and an outdoor unit, the compressor 1 is operated with the second expansion valve 8 fully closed. As a result, the refrigerant does not bypass from the gas-liquid separator 4 to the compressor low-pressure side, so that the compressor suction pressure decreases, and the refrigerant is present in the first connection pipe 5, the indoor heat exchanger 6, and the second connection pipe 7. The refrigerant is drawn into the outdoor unit.
After the refrigerant is sucked, the second on-off valve 12 is closed and the compressor 1 is stopped. Then, the connectors 13 to 16 are separated to separate the indoor unit 18 and the outdoor unit 17. The expansion valve to be fully closed is not the second expansion valve 8 but the outdoor heat exchanger 2.
The first expansion valve 3 between the gas and liquid separator 4 may be used. In this case, the parts where the pressure is reduced by the compressor 1 and the refrigerant is recovered are the gas-liquid separator 4, the connection pipes (5 and 7), and the indoor heat exchanger 6.

By completely closing the second expansion valve 8 or the first expansion valve 3 as described above, the bypass of the refrigerant through the gas-liquid separator 4 can be prevented, so that the indoor heat exchanger can be surely provided. The refrigerant can be recovered from the connection pipe 6 and the connection pipes (5 and 6), and the discharge of the remaining refrigerant to the atmosphere and the addition of the refrigerant at the time of re-installation can be prevented.

The air conditioner of this embodiment may have a mode in which the second pressure reducing mechanism 8 between the gas-liquid separator 4 and the compressor 1 is fully closed regardless of the environmental conditions. By operating in this mode, the compressor suction pressure can be reduced by closing the flow path between the gas-liquid separator 4 and the compressor suction part as described above even under environmental conditions in which the air conditioner does not normally operate. Refrigerant recovery can be performed reliably.

A second embodiment of the present invention will be described with reference to FIG. In FIG. 2, reference numeral 19 denotes a four-way valve as a refrigerant flow switching means. The other parts are the same as those in FIG. 1 of the first embodiment, and the same applies to the operation during the cooling operation. Therefore, the description is omitted, and only the operation during the heating operation will be described. During the heating operation, the second expansion valve 8 is fully closed in the normal heating operation.

The high-temperature and high-pressure refrigerant gas compressed by the compressor 1 passes through the four-way valve 19 and the second connection pipe 7 and radiates heat to the air blown by the indoor blower fan 10 by the indoor heat exchanger 6 to be condensed. Then, it flows into the gas-liquid separator 4 through the first connection pipe 5, but since the second expansion valve 8 is fully closed, it all flows into the first expansion valve, and the low-temperature low-pressure two-phase Becomes a refrigerant,
In the outdoor heat exchanger 2, heat is absorbed from air blown by the outdoor fan 9 to evaporate, and the air returns to the compressor 1 through the four-way valve 19 again. During the defrosting operation, the four-way valve 2 is switched, and the second expansion valve 8 is fully opened.

Thus, the high-temperature and high-pressure refrigerant gas compressed by the compressor 1 passes through the four-way valve 19 and radiates heat to the frost attached to the outdoor heat exchanger 2 by the outdoor heat exchanger 2 to melt the frost, thereby reducing the temperature of the liquid. It becomes a refrigerant and flows into the gas-liquid separator 4 through the first expansion valve 3. Since the second expansion valve 8 is fully opened from the gas-liquid separator 4, most of the refrigerant flows into the gas-liquid separator 4 having a smaller flow path resistance than the indoor heat exchanger 6 and the bypass passage of the compressor suction section. The flow passes through the four-way valve 19 and returns to the compressor 1 again.

As described above, since only a small amount of liquid refrigerant having a low temperature flows into the indoor heat exchanger 6, cold air does not flow into the room and the room temperature does not decrease.

A third embodiment of the present invention will be described with reference to FIGS. FIG. 4 is different from the previous embodiment in the flow path between the gas-liquid separator 4 and the second expansion valve 8 (22 and 23 in the figure) and the flow path between the gas-liquid separator 4 and the indoor heat exchanger (FIG. It has a valve 21 that can simultaneously open and close the middle 24 and 25), and differs in that the first on-off valve 11 is not provided. During the cooling operation, the valve 21 is in the position shown in FIG. 4, and the flow paths 22 and 23 and the flow paths 24 and 25 communicate with each other, so that the gas refrigerant among the gas-liquid two-phase refrigerant on the downstream side of the first expansion valve 3 Is returned to the compressor 1 and the liquid refrigerant flows into the indoor heat exchanger.

When separating the air conditioner, the valve 1
9 is switched to the position shown in FIG.
And the flow of the refrigerant from the flow passages 24 to 25 is prevented.

Thus, the refrigerant flows into the indoor heat exchanger,
Since there is no refrigerant bypass from the gas-liquid separator 4 to the compressor suction section, the compressor suction pressure is reduced and the refrigerant existing in the first connection pipe 5, the indoor heat exchanger 6, and the second connection pipe 7 Is sucked into the outdoor unit. After the refrigerant is sucked, the second on-off valve 12 is closed and the compressor 1 is stopped. Then, the connectors 13 to 16 are separated to separate the indoor heat exchanger and the outdoor heat exchanger.

FIG. 6 shows a fourth embodiment of the present invention. The functions of the valve 21 and the second on-off valve 16 (the valve between the flow paths 27 and 28 in the figure) of the previous embodiment are different from those of the previous embodiment. On-off valve 2 for 3
6 is different. That is, there are three patterns in the valve mode, the first mode in which all of the flow paths 22 and 23, the flow paths 24 and 25, and the flow paths 27 and 28 are communicated, and the flow path 2
2 and 23, the second mode for connecting the flow paths 24 and 25,
This is a third mode in which all channels are closed. The operation is almost the same as in the previous embodiment. FIG. 6 shows a normal cooling operation for performing gas-liquid separation, and FIG.
8 shows a state during the refrigerant recovery operation, and FIG. 8 shows a state when the unit is separated. In this embodiment, since the operation from the normal cooling operation to the refrigerant recovery and the unit separation can be performed by operating only one valve, the operation can be simplified.

[0024]

According to the present invention, at least a compressor, an outdoor heat exchanger, an outdoor unit having a first pressure reducing mechanism, and an indoor unit having an indoor heat exchanger are sequentially connected by piping, and the first pressure reducing mechanism and the indoor heat exchange are connected. A gas-liquid separator is installed between the devices, and the liquid refrigerant separated by the gas-liquid separator is connected so that the indoor heat exchanger and the gas refrigerant flow into the compressor suction part, and the indoor and outdoor units can be separated. In the separation type air conditioner, a variable pressure reduction type second pressure reducing mechanism is provided between the gas-liquid separator and the compressor, and the first or second expansion valve is fully closed during refrigerant recovery. Therefore, the refrigerant recovery operation can be reliably performed. Alternatively, the defrosting operation is performed by switching the four-way valve to fully open the second expansion valve, so that the flow rate of the low-temperature refrigerant flowing into the indoor heat exchanger can be significantly reduced, so that a decrease in the room temperature can be suppressed.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of an air conditioner according to a first embodiment of the present invention.

FIG. 2 is an explanatory view of an air conditioner according to a second embodiment of the present invention.

FIG. 3 is a characteristic diagram illustrating an expansion valve opening degree according to the first embodiment of the present invention.

FIG. 4 is an explanatory diagram of an air conditioner during a cooling operation according to a third embodiment of the present invention.

FIG. 5 is an explanatory diagram of an air conditioner during a refrigerant recovery operation according to a third embodiment of the present invention.

FIG. 6 is an explanatory diagram of an air conditioner during a cooling operation according to a fourth embodiment of the present invention.

FIG. 7 is an explanatory diagram of an air conditioner during a refrigerant recovery operation according to a fourth embodiment of the present invention.

FIG. 8 is an explanatory view of an air conditioner at the time of separation according to a fifth embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Compressor, 2 ... Outdoor heat exchanger, 3 ... First expansion valve, 4
... gas-liquid separator, 5 ... first connection pipe, 6 ... indoor heat exchanger, 7 ... second connection pipe, 8 ... second expansion valve, 9 ... outdoor blower fan, 10 ... indoor blower fan, 11 ... first on-off valve, 12 ... second on-off valve, 13 ... first connector, 14
... second connector, 15 ... third connector, 16 ... fourth connector, 17 ... outdoor unit, 18 ... indoor unit, 19 ... four-way valve, 21 ... four-way valve, 22 ... between gas-liquid separator and six-way valve 23, a flow path between the six-way valve and the second expansion valve, 24, a flow path from the gas-liquid separator and the six-way valve, 25, a flow path between the six-way valve and the first on-off valve, 26,. 6-way valve, 27: flow path between the second on-off valve and the 6-way valve, 28 ... flow path between the 6-way valve and the compressor suction section.

Claims (1)

[Claims] An indoor unit having at least a compressor, an outdoor heat exchanger, an outdoor unit having a first pressure reducing mechanism, and an indoor unit having an indoor heat exchanger are sequentially connected by piping. A gas-liquid separator is installed between the devices, and the liquid refrigerant separated by the gas-liquid separator is connected so that the indoor heat exchanger and the gas refrigerant flow into the compressor suction part, and the indoor and outdoor units can be separated. The air conditioner according to claim 1, further comprising a variable pressure reducing type second pressure reducing mechanism between the gas-liquid separator and the compressor suction unit.