JP2003130492A - Air conditioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multi-type air conditioner capable of sufficiently securing cooling and heating capacities, reducing the input of a compressor, and concurrently operating cooling and heating operations using a reduced amount of refrigerant. SOLUTION: In this air conditioner having a refrigerating cycle, a plurality of compressors 1a, 1b, and 1c, an outdoor heat exchanger 3, an outdoor expansion device 4, a liquid receiver 5, and an indoor expansion device 9 are connected to a plurality of indoor units 40 having indoor heat exchangers 10. High pressure gas refrigerant discharged from one of the plurality of compressors 1 is fed to the indoor unit 40 on a heating use side and condensed in the indoor heat exchanger 10. High pressure gas refrigerant discharged from the other side is condensed in the outdoor heat exchanger 3, supercooled after passing the liquid receiver 5, and fed to the indoor unit 40 on a cooling use side.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air conditioner using a refrigeration cycle, and is particularly suitable for a multi-type air conditioner equipped with two or more compressors and capable of simultaneous cooling and heating operation.

[0002]

2. Description of the Related Art In a cooling-type operation (heating small capacity operation) of a multi-type air conditioner capable of simultaneous cooling and heating operation, when the outside air temperature is low, the outdoor heat exchanger functions as a condenser in the refrigeration cycle on the cooling operation side. Since it works, the amount of heat exchange in the outdoor heat exchanger increases, the condensing pressure decreases, and the discharge pressure of the compressor decreases. On the other hand, in order to keep the blowout temperature of the heating-side indoor unit high, the condensing pressure in the indoor heat exchanger must be increased, and therefore the discharge pressure of the compressor must be increased.

For this reason, in a multi-type air conditioner equipped with two or more compressors and capable of simultaneous cooling and heating operation, in a refrigeration cycle in which the high-pressure refrigerants discharged from the respective compressors are once merged and then branched, For the refrigeration cycle on the cooling operation side, the discharge pressure of the compressor will be increased more than necessary, and the compressor input will be increased accordingly.
Therefore, in order to reduce the compressor input when the cooling operation and the heating operation coexist, it is known to prevent the high-pressure refrigerant discharged from each compressor from being mixed, for example, Japanese Patent Laid-Open No. 5-1.
No. 862 publication.

In the case where the cooling operation and the heating operation are mixed, if the indoor unit is located above the outdoor unit, the cooling capacity will be insufficient unless the liquid refrigerant is supplied to the indoor unit on the cooling use side due to the head difference. Bypassing a part of the liquid refrigerant flowing in the liquid pipe, providing a supercooling circuit for exchanging heat between the low temperature refrigerant obtained by decompressing the liquid refrigerant and the liquid refrigerant flowing in the liquid pipe,
To improve by supplying liquid refrigerant to the indoor unit on the cooling side,
For example, it is disclosed in JP-A-7-4779.

[0005]

In the above prior art, the high pressure refrigerant discharged from each compressor is prevented from being mixed during the simultaneous cooling and heating operation. However, when the load of the cooling operation increases, the cooling side The refrigerant circulation amount decreases. Therefore, a part of the refrigerant discharged from one compressor (on the heating side) is condensed by the outdoor heat exchanger, and the condensed liquid refrigerant may be supplied to the cooling-use side indoor unit, which then becomes similar to the above. The discharge pressure of the compressor must be increased in order to keep the blowout temperature of the heating-use side indoor unit high. In order to increase the discharge pressure of the compressor, the heat transfer area is reduced to reduce the condensation performance, and the outdoor heat exchanger is filled with the liquid refrigerant. Therefore, the amount of refrigerant to be enclosed in the refrigeration cycle increases, which not only increases the cost of the air conditioner, but also causes a large environmental load.

Further, in the one disclosed in Japanese Patent Laid-Open No. 7-4779, a part of the liquid refrigerant supplied to each cooling-use side indoor unit is bypassed at the indoor unit inlet, so that the cooling-use side indoor unit. Depending on the amount of the liquid refrigerant supplied to, it becomes difficult to secure the bypass liquid refrigerant necessary for supercooling the liquid refrigerant. Further, by bypassing, the amount of liquid refrigerant supplied to the cooling-side indoor unit becomes small, and there is a possibility that the cooling capacity cannot be secured.

An object of the present invention is to solve the above-mentioned problems of the prior art, to secure sufficient cooling and heating capacities, to reduce the input of the compressor, and to reduce the amount of refrigerant used. In particular, even when the indoor unit is arranged above the outdoor unit, the cooling capacity of the cooling-use side indoor unit is to be sufficiently ensured.

[0008]

In order to solve the above problems, the present invention provides a plurality of compressors, an outdoor heat exchanger, an outdoor expansion device, a liquid receiver, an indoor expansion device and an indoor heat exchanger. In the air conditioner having a refrigeration cycle in which the high pressure gas refrigerant is discharged from one of the plurality of compressors, the high pressure gas refrigerant is supplied to the indoor unit on the heating use side and condensed in the indoor heat exchanger. The high-pressure gas refrigerant discharged from the other side is condensed in the outdoor heat exchanger, passed through the liquid receiver, and then supercooled and supplied to the indoor unit on the cooling side.

Further, in the above, it is desirable that the compressor on the heating side is an inverter compressor capable of controlling the number of revolutions.

Further, in the above, it is preferable that the compressor on the heating side is an inverter compressor whose rotation speed is controllable and the compressor on the cooling side is a plurality of constant speed type compressors. .

Further, in the above, it is desirable that a plurality of constant speed type compressors are used as the compressors on the cooling side and the number of operating units is controlled.

Further, in the above, it is desirable that the discharge pressure of the compressor on the heating side is set higher than the discharge pressure of the compressor on the cooling side.

Further, in the above, it is preferable that a plurality of outdoor units each including an outdoor heat exchanger, an outdoor expansion device, and a liquid receiver are provided and connected by an on-off valve or a check valve.

Further, in the above, a plurality of outdoor units provided with a compressor, an outdoor heat exchanger, an outdoor expansion device, a liquid receiver, and an outdoor liquid branch pipe through which the liquid refrigerant after passing through the liquid receiver passes. It is preferable that a machine and a liquid connection main pipe in which the outdoor liquid branch pipes are aggregated and piped to the indoor unit side are provided, and supercooling is performed by the liquid connection main pipe.

Further, in the above-mentioned thing, it is desirable that the liquid refrigerant is branched after passing through the liquid receiver, and the refrigerant obtained by decompressing one of the branched ones is supercooled.

Further, in the above-mentioned thing, it is desirable that the liquid refrigerant led out from the liquid receiver is supercooled by a subcooler which is air-cooled together with the outdoor heat exchanger.

Further, in the above, the subcooling is
It is desirable to carry out by a refrigeration cycle in which a compressor, an outdoor heat exchanger, an outdoor expansion device, and a supercooling device are sequentially connected.

Further, according to the present invention, a plurality of compressors, an outdoor heat exchanger, an outdoor expansion device, a liquid receiver, a plurality of indoor units equipped with an indoor expansion device and an indoor heat exchanger, and a high pressure gas connecting main pipe. In an air conditioner having a refrigeration cycle connected with a liquid connection main pipe and a low pressure gas connection main pipe, the discharged high pressure gas refrigerant is supplied to the indoor unit on the heating side via the high pressure gas connection main pipe. A first compressor and a second compressor in which the discharged high-pressure gas refrigerant is condensed in an outdoor heat exchanger and supplied to a cooling-use side indoor unit through a liquid receiver and a liquid connection main pipe. A low-pressure gas connection main pipe that connects the refrigerant evaporated in the indoor unit to the suction sides of the first compressor and the second compressor; and a supercooling device that supercools the liquid refrigerant that is discharged from the liquid receiver. It is equipped with.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION An air conditioner according to an embodiment of the present invention will be described below with reference to FIGS. 1 to 6.
The direction of the arrows shown in FIGS. 1 to 6 indicates the flow direction of the refrigerant during the cooling-based (heating small capacity) operation, and the description will mainly be given during the cooling-based operation. The same is true during heating and heating-only (cooling small capacity) operation.

In FIG. 1, reference numeral 1a denotes an inverter compressor whose rotational speed is variable, and the inverter compressor 1a
The high pressure refrigerant discharged from the high pressure gas connecting branch pipes 151a, 151b connected to the indoor units 40a, 40b, 40c, 40d from the high pressure gas connecting pipe 15 via the four-way valve 2a and the outdoor high pressure gas blocking valve 14, It is supplied to 151c and 151d. The high-pressure refrigerant discharged from the compressors 1b and 1c is the four-way valve 2b, the outdoor heat exchanger 3b, and the outdoor expansion device 4.
b, the liquid receiver 5, the outdoor liquid pipe 6, and the outdoor liquid blocking valve 7 to the indoor units 40a, 40b, 40 from the liquid connection main pipe 8
liquid connection branch pipes 81a and 81b connected to c and 40d,
It is supplied to 81c and 81d.

In the heating-use side indoor unit 40d, the high-pressure gas on-off valve 510d is opened and the low-pressure gas on-off valve 511d is closed, so that the high-pressure gas refrigerant supplied from the high-pressure gas connecting branch pipe 151d is condensed in the indoor heat exchanger 10d. To do. The condensed liquid refrigerant (or gas-liquid two-phase refrigerant) is the indoor expansion device 9d.
Through the liquid connection branch pipe 81d to the liquid connection main pipe 8.

On the other hand, the cooling-use side indoor units 40a, 40b,
At 40c, high pressure gas on-off valves 510a, 510b, 51
0c and 510d are closed, and low pressure gas on-off valves 511a and 51
By opening 1b, 511c, and 511d, the liquid refrigerant (or gas / liquid two-phase refrigerant) supplied from the liquid connecting branch pipes 81a, 81b, and 81c is supplied to the indoor expansion devices 9a, 9b, and 9a.
After depressurizing at c, indoor heat exchangers 10a, 10b, 10c
Evaporates at. The vaporized gas or the gas / liquid two-phase refrigerant is supplied to the low pressure gas connecting branch pipes 111a, 111b, 111c,
It is sucked into the compressors 1a, 1b, 1c through the low pressure gas connection main pipe 11 and the accumulator 13.

Next, a method of controlling the refrigeration cycle when the air conditioning load changes will be described. When the air conditioning load on the heating use side changes, it is possible to set an arbitrary heating capacity by controlling the rotation speed of the inverter compressor 1a. When the air conditioning load on the cooling side changes, the compressor 1b,
When all or one of 1c is an inverter compressor, it is possible to set an arbitrary cooling capacity by controlling the rotation speed of the inverter compressor.

When both the compressors 1b and 1c are constant speed compressors, the bypass amount of the liquid refrigerant bypassing from the downstream side of the receiver 5 is controlled by the opening of the pressure reducing device 16, that is, the pressure reducing device. If the amount of heat exchange between the low-temperature gas / liquid two-phase refrigerant depressurized in 16 and the liquid refrigerant in the outdoor liquid pipe 6 is adjusted by the supercooling device 17, the specific enthalpy amount of the refrigerant at the inlet of the cooling-use side indoor unit is adjusted. Therefore, it is possible to set an arbitrary cooling capacity by controlling the number of operating compressors 1b and 1c together with the above. When both the compressors 1b and 1c are constant speed compressors, a part of the liquid refrigerant condensed in the outdoor heat exchanger 3b is introduced to the outdoor heat exchanger 3a side to cool the indoor units 40a and 40b on the cooling use side. , 40c, and the number of operating compressors 1b, 1c is controlled, and the cooling capacity can be set to an arbitrary value.

When the cooling capacity and the heating capacity are controlled according to the air conditioning load, the high-pressure refrigerant discharged from the inverter compressor 1a and the high-pressure refrigerant discharged from the compressors 1b and 1c are completely separated from each other. Compressor 1a and compressor 1
The discharge pressures of b and 1c can be set separately. For example, when the outside air temperature is low, the amount of heat exchange in the outdoor heat exchanger 3b increases in the refrigeration cycle on the cooling operation side. The condensing pressure in can be kept low,
The discharge pressure of the compressors 1b and 1c can be set low. In addition, from the discharge side of the inverter compressor 1a, the compressor 1
It is desirable to provide a check valve 18 which does not flow to the suction side of a, 1b, 1c.

In the heating operation side refrigeration cycle, the discharge pressure of the inverter compressor 1a may be set higher than the discharge pressures of the compressors 1b and 1c in order to keep the blowout temperature of the heating use side indoor unit 40d high. Compressing the discharge pressure of each of the compressors 1b and 1c used in the refrigeration cycle on the cooling operation side and the inverter compressor 1a used in the refrigeration cycle on the heating operation side to a pressure that maximizes the operation efficiency of the air conditioner. Machine input can be reduced. At this time, by fully closing or slightly opening the outdoor expansion device 4a, the outdoor heat exchanger 3b has a low pressure, and the liquid refrigerant does not accumulate in the outdoor heat exchanger 3b. Therefore, the amount of refrigerant sealed in the refrigeration cycle can be reduced.

FIG. 2 shows another embodiment, which is different from that of FIG. 1 in that an outdoor liquid branch pipe 8a, an outdoor low pressure gas branch pipe 11a, and an outdoor high pressure gas branch pipe 15a connected to an outdoor unit 31a. The outdoor liquid branch pipe 8b, the outdoor low pressure gas branch pipe 11b, and the outdoor high pressure gas branch pipe 15b connected to the outdoor unit 31b are respectively connected to the liquid connection main pipe 8, the low pressure gas connection main pipe 11, and the high pressure gas connection main pipe 15. is doing.

According to the one shown in FIG. 2, even if the generation capacity required for the outdoor unit is increased by adding the indoor unit,
The outdoor unit 31a or the outdoor unit 31b can be added to easily cope with the situation.

FIG. 3 shows still another embodiment.
In place of the supercooling devices 17a and 17b mounted on the outdoor units 31a and 31b for the two, the outdoor units 35a and
The subcooling device 17c is arranged in the liquid connection main pipe 8 that joins the outdoor liquid branch pipes 8a and 8b connected to 35b.

According to this example, even if a large number of outdoor units 35a, 35b are connected, the supercooling device 17c can be installed in one unit.
It is only necessary to dispose it at a location, and when adjusting the heat exchange amount in the subcooling device 17c when the air conditioning load on the cooling side changes, it is sufficient to control only the opening degree of the pressure reducing device 16c. Performance, which in turn improves the reliability of the air conditioner. FIG. 4 shows still another embodiment, in which the liquid refrigerant in the outdoor liquid pipe 6 of FIG. 1 and the refrigerant decompressed after being bypassed from the outdoor liquid pipe 6 are heat-exchanged in the outdoor liquid pipe 6 by a supercooling device 17. The subcooler 20 is supercooled, whereas the subcooler 20 that is air-cooled together with the outdoor heat exchangers 3a and 3b is introduced into the subcooler 20 that is discharged from the liquid receiver 5 to supercool the subcooler. .

When both the compressors 1b and 1c are constant speed compressors, when the air-conditioning load on the cooling side changes, the rotation speed of the outdoor blower 19 is controlled to adjust the air volume, so that the receiver 5 The heat exchange amount in the subcooler 20 of the liquid refrigerant derived from can be adjusted. Therefore, the specific enthalpy amount of the refrigerant at the cooling-use side indoor unit inlet can be controlled, and an arbitrary cooling capacity can be set.

Since the subcooler 20 can be used by combining existing outdoor heat exchangers, it is not necessary to install a supercooling device for supercooling the liquid refrigerant in the outdoor liquid pipe 6, and the subcooler 20 can be made compact or inexpensive. Be advantageous to.

FIG. 5 further shows another embodiment,
While the supercooling device 17 for exchanging heat between the liquid refrigerant in the outdoor liquid pipe 6 and the refrigerant decompressed after bypassing the outdoor liquid pipe 6 in FIG. 1 supercools the liquid refrigerant in the outdoor liquid pipe 6. The liquid refrigerant in the outdoor liquid pipe 6 is supercooled using a refrigeration cycle dedicated to supercooling.

The refrigeration cycle dedicated to subcooling is the compressor 1
h, the outdoor heat exchanger 3h, the outdoor expansion device 4h, and the supercooling device 17h are sequentially connected, and the high-pressure gas refrigerant discharged from the compressor 1h is condensed in the outdoor heat exchanger 3h and condensed. The liquid refrigerant is decompressed by the outdoor expansion device 4h, and the gas / liquid two-phase refrigerant obtained by decompressing is evaporated by exchanging heat with the liquid refrigerant flowing through the outdoor liquid pipe 6 in the supercooling device 17h, It is sucked into the compressor 1h. Supercooling device 1
Since the amount of heat exchange with the liquid refrigerant in the outdoor liquid pipe 6 in 7h can be arbitrarily set by the refrigerating capacity of the refrigeration cycle dedicated to supercooling, the outdoor unit 33 and the indoor units 40a, 4
0b, 40c, 40d connecting pipes 8, 11,
Even when the pipe length of 15 is long, it is possible to suppress the reduction of the cooling capacity in the cooling-use side indoor units 40a, 40b, 40c.

When the air conditioning load on the cooling side changes, both the compressors 1b and 1c are constant speed compressors and the compressor 1h.
Inverter compressor 1
By controlling the number of revolutions of h, the amount of heat exchange with the liquid refrigerant in the outdoor liquid pipe 6 in the supercooling device 17h can be controlled and set to any cooling capacity. Similarly, in the case where the air conditioning load on the cooling side changes, when the compressors 1b, 1c, 1h are all constant-speed compressors, the opening degree of the outdoor expansion device 4h is adjusted and the refrigeration cycle dedicated to supercooling is performed. By adjusting the amount of refrigerant flowing per unit time of circulation, the amount of heat exchange with the liquid refrigerant in the outdoor liquid pipe 6 in the supercooling device 17h can be controlled and set to any cooling capacity.

FIG. 6 shows still another embodiment, in which the cooling-use side indoor unit is the indoor units 40a, 40b, 40c and the heating-use side indoor unit is the indoor unit 40d, during the cooling main operation. .

Indoor units 40a, 40b, 40c on the cooling use side
Since the high pressure gas on-off valves 510a, 510b, 510c in the switching units 51a, 51b, 51c connected to the are closed, the high pressure gas connection branch pipes 151a, 151b, 15
The high-pressure / high-temperature gas refrigerant in 1c is transferred to the switching unit 51.
By exchanging heat with the ambient air near a, 51b, and 51c and condensing, it becomes a liquid refrigerant. This liquid refrigerant can be opened by opening the subcooling bypass valves 513a, 513b, 513c,
It is decompressed by the supercooling decompression devices 520a, 520b, 520c and becomes a low-temperature gas / liquid two-phase refrigerant. Further, a low-temperature gas / liquid two-phase refrigerant and liquid connection branch pipes 81a, 81b, 8
The liquid refrigerant (or gas / liquid two-phase refrigerant) in 1c is the indoor supercooling device 5 in the switching units 51a, 51, 51c.
By exchanging heat with 30a, 530b, 530c, the liquid refrigerant (or the gas / liquid two-phase refrigerant) in the liquid connection branch pipes 81a, 81b, 81c is supercooled (or the gas refrigerant is condensed). The dryness of the refrigerant becomes smaller). Therefore, the cooling-use side indoor heat exchangers 10a, 10
Since the specific enthalpy of the refrigerant at the inlets of b and 10c decreases,
Insufficient cooling capacity of the cooling-use side indoor unit is suppressed. Therefore, the indoor units 40a, 40b, 40c,
When 40d is on the upper side, it is possible to avoid insufficient cooling capacity even when the cooling operation and the heating operation are mixed.

Further, in the case of heating all the rooms or in the heating-main operation, both the outdoor heat exchangers 3a and 3b act as an evaporator, so that the outdoor heat exchangers 3a and 3b are frosted when the outside air temperature is low. Generally, when frost forms on the outdoor heat exchanger, the high-pressure, high-temperature gas refrigerant discharged from the compressor is introduced into the outdoor heat exchanger, and the exhaust heat when the introduced refrigerant is condensed is used to exchange the outdoor heat. Perform defrosting operation to melt the frost on the vessel.
However, since the indoor heat exchanger functions as an evaporator during the defrosting operation, the heating operation cannot be performed, and the comfort is deteriorated.

Therefore, in this example, the check valves 18b and 18c are provided between the four-way valves 2a and 2b and the outdoor high-pressure gas blocking valve 14 so that the high-pressure gas refrigerant discharged from the compressor 1a is four-way. Not flowing into the valve 2b, the compressor 1b, 1
The high-pressure gas refrigerant discharged from c also does not flow into the four-way valve 2a. Therefore, the four-way valves 2a and 2b can be independently driven regardless of the other four-way valves 2b and 2a.
Therefore, since one outdoor heat exchanger can be used as an evaporator and the other outdoor heat exchanger can be used as a condenser, it is not necessary to stop the operation of the heating-use side indoor unit during the defrosting operation. No loss of comfort.

Further, since all the compressors 1a, 1b, 1c are used in the cooling operation during the all-room cooling operation, the high-pressure gas refrigerant discharged from the compressors 1a, 1b, 1c is the outdoor heat exchangers 3a, 3b. Flow into. High pressure gas connection main piping 15
And high-pressure gas connection branch pipes 151a, 151b, 151
The refrigerant in c and 151d does not have a low pressure due to the check valves 18b and 18c. Therefore, when the heating operation is switched to the all-room cooling operation, the high-pressure gas connecting main pipe 15 and the high-pressure gas connecting branch pipes 151a, 151b, 151c,
Since the refrigerant in 151d has a high pressure, the density of the refrigerant is high, so that the amount of the refrigerant increases.

In this example, the subcooling bypass valves 513a, 5
By opening 13b, 513c, and 513d, the refrigerant in the high-pressure gas connection branch pipes 151a, 151b, 151c, 151d can be transferred to the low-pressure gas connection branch pipes 111a, 111b, 1b.
Since it can be led to 11c and 111d, the high pressure gas connection branch pipes 151a, 151b, 151c and 151d.
Since the inside pressure is low, the amount of refrigerant can be reduced. In particular, it is preferable to use a non-azeotropic mixed refrigerant formed by mixing at least two kinds of refrigerants having different boiling points.

[0042]

As described above, according to the present invention,
It is possible to obtain a multi-type air conditioner capable of simultaneous cooling and heating operation while ensuring sufficient cooling and heating capacities, reducing the input of the compressor, and reducing the amount of refrigerant used.

[Brief description of drawings]

FIG. 1 is a system diagram of a refrigeration cycle of an air conditioner according to an embodiment of the present invention (during cooling-main operation).

FIG. 2 is a system diagram of a refrigeration cycle of an air conditioner according to another embodiment of the present invention (during cooling-main operation).

FIG. 3 is a system diagram of a refrigeration cycle of an air conditioner according to another embodiment (during cooling-main operation).

FIG. 4 is a system diagram of a refrigeration cycle of an air conditioner according to another embodiment (during cooling-main operation).

FIG. 5 is a system diagram of a refrigeration cycle of an air conditioner according to another embodiment (during cooling-main operation).

FIG. 6 is a system diagram of a refrigeration cycle of an air conditioner according to another embodiment (during cooling-main operation).

[Explanation of symbols]

1b, 1c, 1e, 1f, 1g, 1h ... Compressor 1a,
1d ... Inverter compressor, 2a, 2b, 2c, 2d, 2
e, 2h ... four-way valve, 3a, 3b, 3c, 3d, 3e, 3
h ... outdoor heat exchangers 4a, 4b, 4c, 4d, 4e, 4
h ... outdoor expansion device, 5 ... liquid receiver, 6, 6a, 6b ... outdoor liquid piping, 7, 7a, 7b ... outdoor liquid blocking valve, 8 ... liquid connection main piping, 8a, 8b ... outdoor liquid branch piping, 81a , 81b,
81c, 81d ... Liquid connection branch piping, 9a, 9b, 9c, 9
d ... Indoor expansion device, 10a, 10b, 10c, 10d ...
Indoor heat exchanger, 11 ... Low-pressure gas connection main piping, 12, 12
a, 12b ... Outdoor low-pressure gas blocking valve, 13, 13a, 13
b ... Accumulator, 14, 14a, 14b ... Outdoor high pressure gas blocking valve, 15 ... High pressure gas connection main piping, 16, 16
a, 16b, 16c ... Pressure reducing device, 17, 17a, 17
b, 17c ... Outdoor supercooling device, 18, 18a, 18b,
18c, 18e ... Check valve, 19 ... Outdoor air blower, 20 ...
Sub cooler, 30, 31a, 31b, 32, 33, 3
4, 35a, 35b ... Outdoor unit, 40a, 40b, 40
c, 40d ... Indoor unit.

Continued front page    (72) Inventor Michiko Endo             Hitachi, Ltd. 390 Muramatsu, Shimizu City, Shizuoka Prefecture             Air conditioning system Shimizu Production Headquarters (72) Inventor Koji Naito             Hitachi, Ltd. 390 Muramatsu, Shimizu City, Shizuoka Prefecture             Air conditioning system Shimizu Production Headquarters (72) Inventor Yasutaka Yoshida             Hitachi, Ltd. 390 Muramatsu, Shimizu City, Shizuoka Prefecture             Air conditioning system Shimizu Production Headquarters (72) Inventor Takeshi Endo             Hitachi, Ltd. 390 Muramatsu, Shimizu City, Shizuoka Prefecture             Air conditioning system Shimizu Production Headquarters F term (reference) 3L092 GA10 HA01 HA12 JA01 JA03                       JA14 KA02 LA05 LA07

Claims (11)

[Claims] 1. An air conditioner having a refrigeration cycle in which a plurality of compressors, an outdoor heat exchanger, an outdoor expansion device, a liquid receiver, a plurality of indoor units equipped with an indoor expansion device and an indoor heat exchanger are connected. In, the high-pressure gas refrigerant discharged from one of the plurality of compressors is supplied to the indoor unit on the heating utilization side and condensed in the indoor heat exchanger, and the high-pressure gas refrigerant discharged from the other is the outdoor unit. An air conditioner that is condensed in a heat exchanger, passes through the liquid receiver, and then is supercooled and is supplied to the indoor unit on the cooling use side. 2. The air conditioner according to claim 1, wherein the compressor on the heating utilization side is an inverter compressor capable of controlling a rotation speed. 3. The compressor according to claim 1, wherein the compressor on the heating use side is an inverter compressor capable of controlling the rotation speed, and the compressor on the cooling use side is composed of a plurality of constant speed type compressors. An air conditioner characterized by being a machine. 4. The air conditioner according to claim 1, wherein the compressor on the cooling side is a plurality of constant speed compressors, and the number of operating compressors is controlled. 5. The air conditioner according to claim 1, wherein the discharge pressure of the compressor on the heating use side is set higher than the discharge pressure of the compressor on the cooling use side. 6. The apparatus according to claim 1, wherein a plurality of outdoor units equipped with the compressor, the outdoor heat exchanger, the outdoor expansion device, and the liquid receiver are provided, each of which is an on-off valve or a check valve. An air conditioner characterized by being connected by a valve. 7. The outdoor liquid according to claim 1, wherein the compressor, the outdoor heat exchanger, the outdoor expansion device, the liquid receiver, and the liquid refrigerant after passing through the liquid receiver pass therethrough. A plurality of outdoor units provided with branch pipes, a liquid connection main pipe that is aggregated with the outdoor liquid branch pipes and piped to the indoor unit side,
And the subcooling is performed in the liquid connection main pipe. 8. The liquid refrigerant according to claim 1, wherein the liquid refrigerant is branched after passing through the liquid receiver, and the subcooling is performed by a refrigerant obtained by decompressing one of the branched ones. An air conditioner. 9. The air conditioner according to claim 1, wherein the subcooler cools the liquid refrigerant drawn from the liquid receiver together with the outdoor heat exchanger by air. 10. The air conditioner according to claim 1, wherein the subcooling is performed by a refrigeration cycle in which a compressor, an outdoor heat exchanger, an outdoor expansion device, and a subcooling device are sequentially connected. Machine. 11. A high-pressure gas connection main pipe, a liquid connection main, and a plurality of compressors, an outdoor heat exchanger, an outdoor expansion device, a liquid receiver, a plurality of indoor units equipped with an indoor expansion device and an indoor heat exchanger. Piping,
In an air conditioner having a refrigeration cycle connected to a low-pressure gas connection main pipe, the discharged high-pressure gas refrigerant is supplied to the indoor unit on the heating utilization side via the high-pressure gas connection main pipe. And a second compressor in which high-pressure gas refrigerant discharged is condensed in the outdoor heat exchanger and is supplied to the indoor unit on the cooling side via the liquid receiver and the liquid connection main pipe. , Supercooling the low-pressure gas connection main pipe connecting the refrigerant evaporated in the indoor unit to the suction side of the first compressor and the second compressor, and the liquid refrigerant drawn from the liquid receiver An air conditioner comprising: a supercooling device.