JP2001056159A - Air conditioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the drop of a room temperature by continuing a heating run while running a defrost run by arranging a pair of compressors in a coolant circuit and by feeding the discharged coolant from one compressor to an outdoor heat exchanger and the discharged coolant from the other compressor to an indoor heat exchanger. SOLUTION: In the heating run, the gas coolant discharged from a first compressor 11a is further compressed by a second compressor 11b and heats indoor air flowing into each indoor heat exchanger 13. A liquid coolant, having flowed out from the heat exchanger 13, flows into a coolant heat exchanger 15, merges with the coolant from the first compressor after being sucked into the second compressor and is compressed to high pressure. The high-pressure liquid coolant is turned to a two-phase gas-liquid coolant and vaporized by heat exchanging with the air flowing into the outdoor heat exchanger 17. The vaporized gas coolant flows out from the heat exchanger 17 and is sucked into the first compressor. The above cycle is repeated and the heating run is performed. When the heat exchanger 17 is frosted with it, the first heat exchanger runs the defrosting run and the second compressor runs the heating run.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air conditioner, and more particularly, to an improvement in a defrost mechanism using gas discharged from a compressor.

[0002]

2. Description of the Related Art Conventionally, a method for performing a defrost operation of an air conditioner using a discharge gas of a compressor, such as a hot gas method or a reverse cycle method, is known (for example, Japanese Patent Application Laid-Open No. 9-210515). Publication (hot gas method) and JP-A-7-332815 (reverse cycle method).

FIG. 16 shows an example of a refrigerant circuit of an air conditioner that performs a hot gas type defrost operation. The refrigerant circuit includes a compressor (1), a four-way switching valve (2), an indoor heat exchanger (3), an indoor expansion valve (4), a liquid receiver (5), and an outdoor expansion valve ( 6), outdoor heat exchanger (7), and the above four-way switching valve
(2) and an accumulator (8) are configured in a closed circuit in which refrigerant pipes are sequentially connected. Then, a hot gas passage (9) for directly supplying the gas refrigerant discharged from the compressor (1) to the outdoor heat exchanger (7) during a defrost operation, which is performed when frost is formed on the outdoor heat exchanger (7) during the heating operation. The hot gas passage (9) is opened during the defrost operation, and hot gas flows directly to the outdoor heat exchanger (7).
(7) is heated to defrost.

Referring to the Mollier diagram of FIG. 18, the circulation operation of the refrigerant when performing the hot gas type defrosting operation will be described. First, the low-pressure refrigerant sucked into the compressor (1) at point a1. Are compressed to the point b1. Most of the refrigerant is depressurized to the point e1 through the pressure reducing valve (9a) and flows into the outdoor heat exchanger (7). Then, it is cooled to the point a1 while heating the outdoor heat exchanger (7), and is sucked into the compressor (1) again through the four-way switching valve (2). In this way, the refrigerant circulates so that the outdoor heat exchanger
(7) The frost is removed.

On the other hand, part of the refrigerant compressed to the point b1 by the compressor (1) also flows into the indoor heat exchanger (3).
At this time, the indoor fan (not shown) is operating, and the refrigerant slightly flowing through the indoor heat exchanger (3) exchanges heat with the indoor air to cool to the point c1 along the broken line in FIG. As a result, the heating is continued although the capacity is reduced. After that, the refrigerant is decompressed to the point d1 by the outdoor expansion valve (6), and then flows into the outdoor heat exchanger (7), where the hot gas passes.
After joining with the refrigerant from (9) and evaporating, the four-way switching valve (2)
(A point a1).

[0006] The reverse cycle system is, for example, shown in FIG.
In the refrigerant circuit of FIG. 17 having a circuit configuration without the hot gas passage (9), when the outdoor heat exchanger (7) is frosted during the heating operation, the four-way switching valve (2) is switched to the broken line side in the figure. As a result, the outdoor heat exchanger (7) is heated with the discharge gas of the compressor (1) while the circulation direction of the refrigerant is reversed, and
The low-temperature refrigerant condensed at that time is heated by the indoor heat exchanger (3) and returned to the compressor (1), and the outdoor heat exchanger
(7) is a method of defrosting.

The circulation operation of the refrigerant when performing the reverse cycle type defrost operation will be described with reference to the Mollier diagram of FIG. 19. First, the low-pressure refrigerant sucked into the compressor (1) at point a2. Is compressed to the high pressure point b2. Then, the refrigerant flows into the outdoor heat exchanger (7), is heated to the outdoor heat exchanger (7), is cooled to the c2 point while being defrosted, and becomes a liquid refrigerant. At this time, the outdoor fan (not shown) is stopped but the refrigerant is cooled because the outdoor heat exchanger (7) is at a low temperature in the heating operation up to that time. Thereafter, the refrigerant is decompressed to the point d2 by the indoor expansion valve (4), and is further heated and evaporated by the indoor heat exchanger (3). At this time, the indoor fan (not shown) is also stopped, but since the indoor heat exchanger (3) is at a high temperature during the heating operation, the refrigerant is heated and evaporated. Then, the heated refrigerant is sucked into the compressor at point a2, and the above cycle is repeated.

[0008]

However, the hot gas method has a drawback that the enthalpy dh1 is small because the refrigerant is circulated in the gas phase during the defrost operation, and a considerable time is required for defrosting. In addition, the heating capacity during that time drops extremely, and this is a relatively long time,
The room temperature tended to decrease.

On the other hand, in the reverse cycle method, the enthalpy dh2 can be made larger than that in the hot gas method, so that the defrosting can be performed in a shorter time than in the hot gas method, but the indoor heat exchanger (3) Because cold refrigerant flows through, cold draft occurs and the indoor temperature decreases,
There was a disadvantage that the indoor comfort was impaired.

[0010] The present invention has been made in view of such problems, and an object of the present invention is to perform indoor defrosting operation using a discharge gas of a compressor in an air conditioner. The goal is to keep the temperature from dropping.

[0011]

According to the present invention, first, the air conditioner is configured as a system using a plurality of compressors (11a, 11b), and these compressors (11a, 11b) perform defrost operation. The heating operation can be performed at the same time.

Specifically, the first solution is a compressor.
It is assumed that the air conditioner is configured to perform the defrost operation using the discharged gas refrigerant of (11a, 11b). As shown in FIGS. 1, 3 and 4, a first compressor (11a) and a second compressor (11b) are provided in the refrigerant circuit, and the first compressor (11a) is operated during defrost operation. The refrigerant discharged is supplied to the outdoor heat exchanger (17), and the refrigerant discharged from the second compressor (11b) is supplied to the indoor heat exchanger (13).

In the above configuration, the first compressor (11a) and the second compressor (11b) are connected in series as shown in FIGS. 1 and 3 to form a two-stage compression mechanism. As shown in FIG. The capacity of the first compressor (11a) during the defrost operation is equal to the capacity of the second compressor (11b).
Is preferably set to be larger than the capacity.

As shown in FIG. 9, the first solution is to provide an intermediate expansion valve (119) in a liquid line (124L) between an indoor heat exchanger (122) and an outdoor heat exchanger (114). ) And gas-liquid separator (1
20), and the gas outlet of the gas-liquid separator (120) is connected to a first compressor (112) and a second compressor (11) for performing two-stage compression.
7), and the refrigerant discharged from the first compressor (112) is supplied to the outdoor heat exchanger (1) during the defrost operation.
14), flows into the gas-liquid separator (120), and the refrigerant discharged from the second compressor (117) flows into the gas-liquid separator (120) through the indoor heat exchanger (122). The gas refrigerant in the liquid separator (120) can be configured to be sucked into each of the compressors (112, 117).

Further, as shown in FIG. 14, the first solution is to provide a gas line (124G) between a first compressor (112) and a second compressor (117) for performing two-stage compression. Gas-liquid separator (12
0), and the liquid outlet of the gas-liquid separator (120) is connected to a liquid line (124L) between the outdoor heat exchanger (114) and the indoor heat exchanger (122). 124L) with the indoor expansion valve (1
23) through the intermediate expansion valve (119) to the gas inlet to the gas-liquid separator (120), while connecting between the indoor expansion valve (123) and the intermediate expansion valve (119) and the gas-liquid separator (119). 120) and a communication passage (1) having an on-off valve (162) between the liquid outlet of the outdoor expansion valve (115) and the outdoor expansion valve (115).
63) may be connected.

In the refrigerant circuit configured as described above, as shown in FIG. 10, an unload passage (141) for bypassing a part of the refrigerant discharged from the second compressor (117) to the suction side during the defrost operation is provided. Preferably, an on-off valve (142) is provided in the unload passage (141).

Further, in the refrigerant circuit having the above configuration, as shown in FIGS. 11, 12, and 15, the refrigerant is discharged from the first compressor (112) during the defrost operation and is supplied to the outdoor heat exchanger (11).
4) A first bypass passage (151) for bypassing a part of the refrigerant flowing out to the suction side of the first compressor (112) is provided, and a flow control mechanism (153) is provided in the first bypass passage (151). Or a second bypass passage (1) that allows a part of the refrigerant discharged from the second compressor (117) to flow out of the indoor heat exchanger (122) to the suction side of the second compressor (122) during the defrost operation.
52), and a flow control mechanism is provided in the second bypass passage (152).
(154), and both a first bypass passage (151) and a second bypass passage (152) are provided, each of which has a flow control mechanism.
It is preferable to provide (153, 154).

In these configurations, the first bypass passage
(151) is a liquid line (124L) between the outdoor heat exchanger (114) and the outdoor expansion valve (115), as shown in FIG.
12) to the gas line (124G) on the suction side,
As shown in FIG. 2, a liquid line (124L) between the outdoor expansion valve (115) and the gas-liquid separator (120) and a gas line (124G) on the suction side of the first compressor (112) are connected. can do. As shown in FIGS. 11 and 15, the second bypass passage (152) is connected to the liquid line (124L) between the indoor heat exchanger (122) and the intermediate expansion valve (119) and the second compressor (117). ) And a liquid line (124L) between the intermediate expansion valve (119) and the gas-liquid separator (120) as shown in FIG.
And a gas line (124G) on the suction side of the second compressor (117).

Further, in the above configuration, FIG.
As shown in (a), the gas-liquid separator (1
A refrigerant heating means (120a) for heating the refrigerant is provided in the refrigerant inflow pipe (124L) to the refrigerant 20), or as shown in FIG.
A refrigerant heating means (120a) for heating the refrigerant is provided in the container body of the gas-liquid separator (120), or the refrigerant is kept warm in the container body of the gas-liquid separator (120) as shown in FIG. A refrigerant heat retaining means (120b) may be provided.

Next, a second solution of the present invention is to maintain the indoor heat exchanger at a high pressure during the defrost operation.

[0021] Specifically, the second solving means is, as shown in Fig. 5, in an air conditioner configured to perform a defrost operation by a gas refrigerant discharged from a compressor (11b). Bypass passage connected in parallel with the vessel (13)
(51) and high-pressure holding means (14, 53) for closing the indoor heat exchanger (13) while holding it at a high pressure during defrost operation, or as shown in FIG. A plurality of indoor heat exchangers (13a, 13b) connected in parallel are provided, and high-pressure holding means (14a, 53) for closing a predetermined indoor heat exchanger (13a) at a high pressure during defrost operation is provided. The configuration is as follows.

In a configuration in which a plurality of indoor heat exchangers (13a, 13b) are connected in parallel, a predetermined indoor heat exchanger (13a) that is maintained at a high pressure by the high-pressure holding means (14a, 53) during defrost operation is used. The indoor heat exchanger for a living room may be used, and the other indoor heat exchanger (13b) may be used for a non-living room such as a corridor or entrance.

In the above configuration, the high-pressure holding means (14, 53)
As shown in FIGS. 5 and 6, (14a, 53) can be constituted by an opening / closing mechanism capable of closing the inlet side and the outlet side of the indoor heat exchanger (13, 13a). One of the opening and closing mechanisms is constituted by an electronic expansion valve (14, 14a), and the other is a closing valve (5, 14).
3).

In the first and second solving means, FIGS. 7, 9 to 12, 14, and 15 are used.
As shown in (11), heat source units (71) and (111) provided with compressors (81, 82) and (112) and a utilization unit (73) provided with indoor heat exchangers (91) and (122). ) And (121), and the heat source units (71) and (111) and the utilization units (73) and (121)
A configuration in which auxiliary compressors (93) and (117) are provided and connected via detachable intermediate units (72) and (116) for compressing the refrigerant in two stages can be adopted.

In the first solution, when frost is formed on the outdoor heat exchanger (17), when the defrost operation for removing the frost of the outdoor heat exchanger (17) is performed, the first compressor is used. The refrigerant discharged from the second compressor (11b) is supplied to the indoor heat exchanger (13) while the refrigerant discharged from (11a) is supplied to the outdoor heat exchanger (17).
Therefore, the heating operation by the second compressor (11b) can be performed while the defrost operation by the first compressor (11a) is performed.

In the defrost operation, the first compressor (11
When the capacity of a) is larger than the capacity of the second compressor (11b), the capacity of the indoor heat exchanger (1) is discharged from the second compressor (11b).
3) While evaporating the liquid refrigerant that has passed through with the gas refrigerant discharged from the first compressor (11a), the gas refrigerant discharged from the first compressor (11a) reliably removes frost from the outdoor heat exchanger (17). Can be removed.

Specifically, an intermediate expansion valve (119) is connected to a liquid line (124L) between the indoor heat exchanger (122) and the outdoor heat exchanger (114).
And a gas-liquid separator (120).
The gas outlet of 20) is connected to a gas line (124G) between a first compressor (112) and a second compressor (117) for performing two-stage compression,
During the defrost operation, the refrigerant discharged from the first compressor (112) flows into the gas-liquid separator (120) via the outdoor heat exchanger (114), and the refrigerant discharged from the second compressor (117) is discharged from the indoor heat exchanger. Exchanger
(122) to the gas-liquid separator (120)
(120), the refrigerant in the first compressor (112) and the refrigerant in the second compressor (117) are separated by a gas-liquid separator. When mixing in the (120), the liquid refrigerant from the indoor heat exchanger (122) is
14), it can be circulated to the indoor heat exchanger (122) side and the outdoor heat exchanger (114) side while heating and evaporating by the residual heat of the gas refrigerant from It can be carried out.

The gas-liquid separator (120) is connected to the first compressor (11).
2) and a gas line (124G) between the second compressor (117) and the liquid outlet of the gas-liquid separator (120) with the outdoor heat exchanger (114) and the indoor heat exchanger (122). Liquid line between (124
L) and the liquid line (124L) is connected from the indoor expansion valve (123) to the gas inlet to the gas-liquid separator (120) via the intermediate expansion valve (119), while the indoor expansion valve (123 ) And the intermediate expansion valve (11
9), the liquid outlet of the gas-liquid separator (120) and the outdoor expansion valve (11
In the case where a communication passage (163) having an on-off valve (162) is connected between the outdoor heat exchanger (114) and the communication passage (163), the refrigerant discharged from the first compressor (112) is connected to the communication passage (163). The refrigerant discharged from the second compressor (117) flows from the indoor heat exchanger (122) to the intermediate expansion valve (119) while flowing to the intermediate expansion valve (119) via However, by circulating the air through the outdoor heat exchanger (114) and the indoor heat exchanger (122), the heating operation and the defrost operation can be performed simultaneously.

Further, in these refrigerant circuits, an unload passage (141) for bypassing a part of the refrigerant discharged from the second compressor (117) to the suction side during the defrost operation is provided.
Since the low pressure on the side of the second compressor (117) is higher than the low pressure on the side of the first compressor (112), the amount of refrigerant sucked into the side of the first compressor (112) increases, and as a result, Outdoor heat exchanger (11
4) The circulation amount of the refrigerant on the side becomes larger than the circulation amount of the refrigerant on the indoor heat exchanger (122) side.

Further, during the defrost operation, the first compressor (11
2), a first bypass passage (151) for bypassing a part of the refrigerant discharged from the outdoor heat exchanger (114) to the suction side of the first compressor (112) is provided. 114)
A part of the refrigerant discharged from the second compressor (117) and flowing out of the indoor heat exchanger (122) is bypassed to the suction side of the second compressor (122) because the circulation amount of the refrigerant on the side increases. The provision of the second bypass passage (152) increases the amount of refrigerant circulating on the indoor heat exchanger (122) side.
The stagnation of the liquid refrigerant at 20) can be suppressed.

Further, the gas-liquid separator (1
20), refrigerant heating means (120a) is provided in the refrigerant inflow pipe (124L) or the container body of the gas-liquid separator (120), or the gas-liquid separator (1
In the case where the refrigerant heat retaining means (120b) is provided in the container body of (20), the gas-liquid separator is increased by increasing the dryness of the refrigerant.
(120) It is possible to suppress the stay of the liquid refrigerant inside.

In the second solution, when the bypass passage (51) is provided in parallel with the indoor heat exchanger (13),
During the defrost operation, the gas refrigerant discharged from the compressor (11b) is supplied to the outdoor heat exchanger (17) while the indoor heat exchanger (13) is maintained at a high pressure by the high-pressure holding means (14, 53). In this case, the refrigerant circulates through the outdoor heat exchanger (17) and the bypass passage (51). Then, the refrigerant flows from the compressor (11b) to the outdoor heat exchanger (17) to defrost the outdoor heat exchanger (17),
It returns to the compressor through the bypass passage (51).

On the other hand, in a system in which a plurality of indoor heat exchangers (13a, 13b) are connected in parallel, when the predetermined indoor heat exchanger (13a) is maintained at a high pressure during the defrost operation, the refrigerant becomes another refrigerant. Circulates through the indoor heat exchanger (13b).
At this time, the refrigerant is transferred from the compressor (11b) to the outdoor heat exchanger (17).
After defrosting the outdoor heat exchanger (17) by flowing the same to the other indoor heat exchanger (13b), it can be heated and then returned to the compressor.

[0034]

According to the first solution, the heating operation can be continued when the outdoor heat exchanger (17) is defrosted, so that the indoor temperature is prevented from lowering during the defrost operation. it can. In particular, the capacity of the first compressor (11a) is
(11b), it is ensured that the refrigerant of the second compressor (11b) is evaporated while the outdoor heat exchanger (17) is defrosted by the refrigerant of the first compressor (11a). (11a, 11b)
The liquid refrigerant can be prevented from returning to the first position.

Further, the first compressor (11) is provided by the gas-liquid separator (120).
2) and the refrigerant from the second compressor (117) while being circulated through the outdoor heat exchanger (114) and the indoor heat exchanger (122) while mixing the refrigerant from the second compressor (117). By providing an unload passage (141) for bypassing a part of the refrigerant discharged from the compressor (117) to the suction side, the amount of refrigerant circulating on the first compressor (112) side is reduced by the second compressor (117). Since it is larger than the circulation amount of the refrigerant, the defrost time can be reduced.

In the defrost operation, the first compressor (11
2), a first bypass passage (151) for bypassing a part of the refrigerant discharged from the outdoor heat exchanger (114) to the suction side of the first compressor (112) is provided. 114)
Since the circulation amount of the refrigerant on the side increases, the defrost time can be reduced. A part of the refrigerant discharged from the second compressor (117) and flowing out of the indoor heat exchanger (122) is transferred to the second compressor (1).
22) A second bypass passage (152) for bypassing to the suction side of
When the air conditioner is provided, the amount of circulation of the refrigerant on the side of the indoor heat exchanger (122) increases, so that even if the defrost time becomes long, the temperature drop in the room can be reliably suppressed. In any case, the stagnation of the refrigerant in the gas-liquid separator (120) can be suppressed.

Further, the gas-liquid separator (1
20), refrigerant heating means (120a) is provided in the refrigerant inflow pipe (124L) or the container body of the gas-liquid separator (120), or the gas-liquid separator (1
When the refrigerant heat retaining means (120b) is provided in the container body of (20), the stagnation of the liquid refrigerant in the gas-liquid separator (120) can be more reliably suppressed, and compared with the case where such means is not provided. Thus, the defrost operation can be continuously performed for a sufficiently long time, and the frequency of the defrost operation can be reduced.

According to the second solution, in the system provided with the bypass passage (51) at the time of the defrost operation, the operation of circulating the refrigerant in the gas phase is performed, and the plurality of indoor heat exchangers are provided. When a predetermined indoor heat exchanger (13a) is maintained at a high pressure in a system provided with (13a, 13b), the refrigerant is removed using the outdoor heat exchanger (17) and other indoor heat exchangers (13b). An operation of circulating while condensing and evaporating is performed.

In any case, only a part of the refrigerant is not passed to the indoor heat exchanger (13) during the defrost operation, so that the defrost operation can be performed in a shorter time than before. Further, since the indoor heat exchanger (13) is maintained at a high pressure to maintain a high temperature state, no cold draft occurs. Therefore, in any case, defrosting can be performed in a shorter time than in the conventional case, and a decrease in room temperature can be prevented.

When the defrost operation is performed using the indoor heat exchanger (13b) for a non-living room such as a corridor or an entrance during the defrost operation, the temperature in the non-living room decreases somewhat, Since the room is a non-living room, the influence is small and the temperature of the living room can be reliably prevented from lowering.

One of the opening and closing mechanisms provided on the inlet side and the outlet side of the indoor heat exchanger (13) as the high pressure holding means (14, 53) (14a, 53) is constituted by an electronic expansion valve (14, 14a). In addition, the number of dedicated opening and closing mechanisms can be reduced, and the configuration can be prevented from becoming complicated.

[0042]

Embodiment 1 Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows an air conditioner (1) according to the first embodiment.
It is a refrigerant circuit diagram of (0). This air conditioner (10) has two compressors connected so that they can be used in series.
(11a, 11b) (Lower stage first compressor (11a) and upper stage second compressor (11a)
The compressor (11b) employs a two-stage compression mechanism. The air conditioner (10) is configured such that the heating operation can be performed by single-stage compression and two-stage compression, while the outdoor heat exchanger can be defrosted while performing the single-stage heating operation. . Also, the cooling operation is configured to be performed by single-stage compression and two-stage compression. In this embodiment, the capacity of the first compressor (11a) is set to be larger than the capacity of the second compressor (11b).

The refrigerant circuit of the air conditioner (10) is specifically configured as follows. That is, first,
The discharge side of the second compressor (11b) is a four-way switching valve (12), an indoor heat exchanger (13), an indoor expansion valve (14), a refrigerant heat exchanger (15), an outdoor expansion valve (16), an outdoor Heat exchanger (17), four-way switching valve (12),
The second accumulator (18b) and the suction side of the second compressor (11b) are connected by a refrigerant pipe in this order to form a closed circuit.

The air conditioner (10) of the first embodiment is configured as a system in which a plurality of indoor units (24) are connected in parallel. Each indoor unit (24) is provided with the indoor heat exchanger (13) and the indoor expansion valve (14).

The refrigerant heat exchanger (15) exchanges heat between the high-pressure refrigerant flowing out of the indoor heat exchanger (13) and the refrigerant depressurized to an intermediate pressure after flowing out of the indoor heat exchanger (13). And a first heat exchange section (15a) through which high-pressure refrigerant flows, and a second heat exchange section (15b) through which intermediate-pressure refrigerant flows.
The refrigerant heat exchanger (15) may be, for example, a double-pipe heat exchanger, a plate heat exchanger, or the like.

Then, the liquid line between the refrigerant heat exchanger (15) and the indoor expansion valve (14) branches, and the second heat exchange of the refrigerant heat exchanger (15) is performed via the intermediate expansion valve (19). (15b). The second heat exchange section (15b) joins the suction-side gas line of the second compressor (11b). The intermediate-pressure gas refrigerant flowing through the second heat exchange section (15b) is supplied to the second compressor (11b).
A gas injection operation is performed to return to.

In this refrigerant circuit, three solenoid valves (20, 21, 2) are used to switch between single-stage compression operation and two-stage compression operation.
2) is provided. First, the four-way switching valve (12) and the second
A first solenoid valve (20) is provided between the accumulators. Further, a gas pipe on the discharge side of the first compressor (11a) is branched into two, and one of the discharge pipes is connected to the outdoor expansion valve via the second solenoid valve (21) and the capillary tube (23). (16) is connected to a liquid line between the outdoor heat exchanger (17), and the other of the discharge pipes is connected via a third solenoid valve (22) to a second heat exchanger (15) of the refrigerant heat exchanger (15). It merges with the exit side of 15b).

The suction side of the first compressor (11a) is
It is connected to a four-way switching valve (12) via an accumulator (18a).

-Operation- Next, the operation of the air conditioner (10) will be described.

During the heating operation, the four-way switching valve (12) is set to the state shown by the solid line in FIG. When the heating operation is performed by the two-stage compression, the third solenoid valve (22) is set to “open” and the first solenoid valve is set to “open”.
(20) and the second solenoid valve (21) are set to "closed". At this time, the indoor expansion valve (14) is controlled to fully open, and the outdoor expansion valve (16)
The opening of the intermediate expansion valve (19) is controlled so as to reduce the pressure of the high-pressure liquid refrigerant to a predetermined intermediate pressure.

In this state, the gas refrigerant discharged from the first compressor (11a) is further compressed by the second compressor (11b) to a high pressure, and flows into each indoor heat exchanger (13). In each indoor heat exchanger (13), the refrigerant exchanges heat with indoor air and condenses, thereby heating the indoor air. And the heated air
The air is blown back into the room by an indoor fan (not shown) to heat the room.

The high-pressure liquid refrigerant flowing out of the indoor heat exchanger (13) once merges through the indoor expansion valve (14), and then branches again. One of the refrigerants is the first refrigerant of the refrigerant heat exchanger (15). Heat exchange unit (15
a), the other refrigerant is reduced to an intermediate pressure by the intermediate expansion valve (19), becomes a gas-liquid two-phase refrigerant, and flows into the second heat exchange part (15b) of the refrigerant heat exchanger (15). .

In the refrigerant heat exchanger (15), the first heat exchange section
The high-pressure refrigerant flowing through (15a) exchanges heat with the intermediate-pressure refrigerant flowing through the second heat exchange section (15b). As a result, the two-phase refrigerant at the intermediate pressure is heated and the second heat exchange part (15) of the refrigerant heat exchanger (15) is heated.
b). Then, it is sucked into the second compressor (11b), merges with the refrigerant from the first compressor (11a), and is compressed to a high pressure.

On the other hand, in the refrigerant heat exchanger (15), the high-pressure liquid refrigerant on the side of the first heat exchange section (15a) is supercooled and the first heat exchange section (15a) of the refrigerant heat exchanger (15). Spill out of. The supercooled high-pressure liquid refrigerant is reduced to a low pressure by the outdoor expansion valve (16), and becomes a gas-liquid two-phase refrigerant. Then, the gas-liquid two-phase refrigerant flows into the outdoor heat exchanger (17), exchanges heat with outdoor air, and evaporates. The evaporated gas refrigerant flows out of the outdoor heat exchanger (17) and is sucked into the first compressor (11a) via the four-way switching valve (12) and the first accumulator (18a).
By repeating the above cycle, a high-capacity heating operation by two-stage compression is performed while performing a gas injection operation at a low outside air temperature or the like.

Next, when the heating operation is performed by the single-stage compression, only the second compressor (11b) is used. And the first solenoid valve
(20) is set to “open”, and the second solenoid valve (21) and the third solenoid valve (22) are set to “close”. Further, the indoor expansion valve (14) is controlled to be fully opened, the outdoor expansion valve (16) is controlled in opening so as to reduce the high-pressure liquid refrigerant to a predetermined low pressure, and the intermediate expansion valve (1) is controlled.
9) is controlled to fully close. In this way, gas injection is not performed during single-stage compression (however, gas injection can be performed by opening the intermediate expansion valve (19)).

In this state, the gas refrigerant discharged from the second compressor (11b) flows into the indoor heat exchanger (13) and condenses,
After heating the indoor air, the indoor expansion valve (14) and the refrigerant heat exchanger
(15), and the pressure is reduced by the outdoor expansion valve (16). Then, the decompressed low-pressure two-phase refrigerant flows into the outdoor heat exchanger (17), exchanges heat with the outdoor air, evaporates, and then the four-way switching valve (1
2), it is sucked into the second compressor (11b) via the first solenoid valve (20) and the second accumulator (18b). By repeating the above cycle, the heating operation by single-stage compression is performed.

By performing the single-stage compression or the two-stage compression heating operation as described above, when frost is formed on the outdoor heat exchanger (17), the defrost operation is performed. In the first embodiment, the defrost operation can be performed in parallel with the heating operation as described above, and the first compressor (11a) is used for the defrost operation and the second compressor (11b) is used for the heating operation.

At this time, the first solenoid valve (20) and the second solenoid valve (2
1) is set to “open”, and the third solenoid valve (22) is set to “closed”. The indoor expansion valve (14), the outdoor expansion valve (16), and the intermediate expansion valve (19) are controlled in the same manner as in the single-stage compression operation. Even in this case, gas injection can be performed as needed.

The circulation operation of the refrigerant in this state will be described with reference to the Mollier diagram shown in FIG. 2nd compressor
The gas refrigerant compressed and discharged from the low pressure (point A) to the high pressure (point B) in (11b) flows into the indoor heat exchanger (13) in the same manner as when performing the single-stage compression heating operation. Then, the room air is heated, condensed and cooled to the point C. Then, the condensed liquid refrigerant passes through the indoor expansion valve (14) and the refrigerant heat exchanger (15), and is decompressed to the point D by the outdoor expansion valve (16) to become a two-phase refrigerant, and the outdoor heat exchanger ( 17).

On the other hand, also in the first compressor (11a), the refrigerant is compressed from point A to point B and discharged. This gas refrigerant passes through the capillary tube (23), decompresses to the point E in the gas phase, and flows into the outdoor heat exchanger (17).
At this time, the gas refrigerant joins the two-phase refrigerant that has passed through the outdoor expansion valve (16) to evaporate the refrigerant and heat the outdoor heat exchanger (17), and then heats the outdoor heat exchanger (17). ). Then, the refrigerant is branched after passing through the four-way switching valve (12), and is sucked into the compressors (11a, 11b).

As described above, in the first embodiment, while the outdoor heat exchanger (17) is heated by the refrigerant on the first compressor (11a) side,
Since the liquid refrigerant from the indoor heat exchanger (13) is also evaporated, the heating operation by the second compressor (11b) and the defrost operation by the first compressor (11a) are simultaneously possible. . When the defrost of the outdoor heat exchanger (17) is completed, the heating operation can be repeated again by single-stage compression or two-stage compression.

In the cooling operation, the four-way switching valve (12) is set to the state shown by the broken line, and the refrigerant is condensed in the outdoor heat exchanger (17) and circulated while being evaporated in the indoor heat exchanger (13). Can be performed. At that time, the outdoor expansion valve (16) is controlled to be fully opened, the intermediate expansion valve (19) is controlled to be fully closed, the refrigerant heat exchanger (15) is not used, and the indoor expansion valve (14) supplies high-pressure refrigerant. The opening is controlled to a predetermined value so as to reduce the pressure.

In the present embodiment, the heating operation by the two-stage compression is performed by using the high-pressure refrigerant and the intermediate-pressure refrigerant in the refrigerant heat exchanger.
Although the description has been made assuming that gas injection is performed by performing heat exchange in (15), gas injection is not necessarily performed. In that case, the intermediate expansion valve (19)
Is set to “closed”. However, when gas injection is performed, the amount of gas refrigerant sucked into the second compressor (11b) increases, and the amount of refrigerant flowing through the indoor heat exchanger (13) increases. Heating capacity can be increased.

According to the first embodiment, the refrigerant on the first compressor (11a) side is circulated in the gas phase while the defrost operation is performed while performing the defrost operation.
Since the heating operation can be continued by the compressor (11b), the heating capacity does not decrease. Therefore, even if the time required for the defrost operation becomes relatively long, it is possible to prevent the room temperature from decreasing.

[0066]

Second Embodiment As shown in FIG. 3, a second embodiment of the present invention uses a gas-liquid separator (31) instead of the refrigerant heat exchanger (15) of the first embodiment. It is.

More specifically, in the air conditioner (30), the discharge side of the second compressor (11b) includes a four-way switching valve (12), an indoor heat exchanger (13), and an indoor expansion valve (14). , Intermediate expansion valve (19), gas-liquid separator (31), outdoor expansion valve (16), outdoor heat exchanger (17), four-way switching valve (12), first solenoid valve (20), second Accumulator (18
b), and connected by refrigerant piping in the order of the suction side of the second compressor (11b) to form a closed circuit. The gas outlet of the gas-liquid separator (25) joins the suction pipe of the second compressor (11b) via the fourth solenoid valve (32).

In the first compressor (11a), the discharge-side gas pipe is branched into two, and one of the discharge pipes is connected to the outdoor expansion valve (16) via the second solenoid valve (21). The other end of the discharge pipe is connected to the gas inlet of the gas-liquid separator (31) via the third solenoid valve (22). The suction side pipe of the first compressor (11a) is connected to the four-way switching valve (12) and the first solenoid valve (20) via the first accumulator (18a).
Connected to the gas pipe between.

-Operating operation- In the second embodiment, when performing the heating operation by the two-stage compression, the third solenoid valve (22) and the fourth solenoid valve (32) are set to "open", and the first solenoid valve is set. (20) and the second solenoid valve (21) are set to "closed". Also, the indoor expansion valve (14) is controlled to be fully open, the intermediate expansion valve (19) is controlled in opening so as to reduce the high-pressure refrigerant to a predetermined intermediate pressure, and the outdoor expansion valve (16) is controlled to the intermediate pressure refrigerant. Is controlled to reduce the pressure to a predetermined low pressure.

In this state, the gas refrigerant discharged from the first compressor (11a) is sucked into the second compressor (11b) via the gas-liquid separator (31) and is further compressed. And this high-pressure gas refrigerant flows into the indoor heat exchanger (13) and heats the indoor air,
It condenses and changes phase to liquid refrigerant. The liquid refrigerant passes through the indoor expansion valve (14), and is decompressed when passing through the intermediate expansion valve (19), and partially expands into a gas-liquid two-phase refrigerant having an intermediate pressure. The gas-liquid two-phase refrigerant flows into the gas-liquid separator (31) and is separated into a gas refrigerant and a liquid refrigerant. The liquid refrigerant flows out of the gas-liquid separator (31), becomes a low-pressure two-phase refrigerant at the outdoor expansion valve (16), and flows into the outdoor heat exchanger (17). The two-phase refrigerant exchanges heat with outdoor air in the outdoor heat exchanger (17), evaporates, and is then sucked into the first compressor (11a) through the four-way switching valve (12) and the first accumulator (18a). Then, the refrigerant circuit circulates again.

On the other hand, after passing through the intermediate expansion valve (19), the gas refrigerant separated from the liquid refrigerant in the gas-liquid separator (31) is mixed with the gas refrigerant discharged from the first compressor (11a). Then, it is sucked into the second compressor (11b). Due to this gas injection, the circulation amount of the gas refrigerant flowing through the indoor heat exchanger (13) increases, and the heating capacity improves.

Next, when performing the heating operation by single-stage compression without performing gas injection, the first compressor (11a) is stopped and only the second compressor (11b) is used. Then, the first solenoid valve (20) is set to "open", and the other second, third, and fourth solenoid valves (21, 22, 32) are set to "close". The indoor expansion valve (14) and the intermediate expansion valve (19) are controlled to be fully opened, and the outdoor expansion valve (16) is controlled in opening so as to reduce the pressure of the high-pressure refrigerant to a predetermined low pressure.

In this state, the gas refrigerant discharged from the second compressor (11b) flows into the indoor heat exchanger (13) and heats and condenses indoor air in the indoor heat exchanger (13). . The condensed liquid refrigerant passes through the indoor expansion valve (14), the intermediate expansion valve (19), and the gas-liquid separator (31), and is depressurized by the outdoor expansion valve (16), and the outdoor heat exchanger (17) Flows into. And the refrigerant is an outdoor heat exchanger
In (17), the refrigerant exchanges heat with the outdoor air to evaporate, and the evaporated gas refrigerant passes through the four-way switching valve (12), the first solenoid valve (20), and the second accumulator (18b). (11b). The heating operation by single-stage compression is performed by repeating the above cycle.

On the other hand, when frost forms on the outdoor heat exchanger (17), a defrost operation is performed. This defrost operation is configured to be performed while performing the heating operation, as in the first embodiment.

At this time, the first solenoid valve (20) and the second solenoid valve (2
1) is set to “open”, and the third solenoid valve (22) and the fourth solenoid valve (3
2) is set to “closed”. In addition, each expansion valve (14, 16, 19)
Is controlled in the same manner as in the single-stage compression heating operation.

With the above setting, the refrigerant discharged from the second compressor (11b) is supplied to the indoor heat exchanger (1b) in the same manner as in the single-stage compression heating operation.
After condensing in 3), it passes through the indoor expansion valve (14), the intermediate expansion valve (19) and the gas-liquid separator (31). Then, the pressure is reduced by the outdoor expansion valve (16) to become a low-pressure gas-liquid two-layer refrigerant, and flows into the outdoor heat exchanger (17).

On the other hand, the refrigerant discharged from the first compressor (11a) directly flows into the outdoor heat exchanger (17) through the second solenoid valve (21). At this time, the refrigerant discharged from the first compressor (11a) also heats the outdoor heat exchanger (17) while evaporating the gas-liquid two-phase refrigerant that has passed through the outdoor expansion valve (16). The frost adhering to the vessel (17) is removed. After that, the flow is divided via the four-way switching valve (12), and each of the compressors (11a, 1
Inhaled in 1b). When the defrosting of the outdoor heat exchanger (17) is completed while circulating the refrigerant in this way, it becomes possible to perform the single-stage compression or the two-stage compression heating operation again.

Also in the second embodiment, as in the first embodiment, the cooling operation can be performed by switching the four-way switching valve (12) to the state shown by the broken line and circulating the refrigerant in the reverse direction.

In the second embodiment, the gas injection is not performed during the single-stage compression operation. However, the intermediate expansion valve (19) reduces the high-pressure liquid refrigerant to the intermediate pressure and the fourth solenoid valve ( Gas injection may be performed by opening step 32).

-Effects of Second Embodiment- In the second embodiment as well, the heating operation can be continued during the defrost operation as in the first embodiment, so that the heating capacity does not decrease and the required time for the defrost operation is compared. Even if the target lengthens, the indoor temperature can be prevented from lowering.

[0081]

Embodiment 3 In Embodiment 3 of the present invention, as shown in FIG. 4, two compressors (11a, 11b) are connected not in series but in parallel. Two compressors (11
a, 11b) are a first compressor (11a) having a variable capacity by controlling the frequency of an inverter, and a second compressor having a constant capacity.
(11b). The first compressor (11a) is configured such that its capacity can be adjusted to a capacity equal to or larger than the capacity of the second compressor (11b).

In this air conditioner (40), the first compressor (1
1a) and the discharge port of the second compressor (11b) are connected via a first solenoid valve (20), and the first solenoid valve (2
The gas pipe on the second compressor (11b) side of the four-way switching valve (1)
2), each indoor heat exchanger (13), each indoor expansion valve (14), liquid receiver (4
1), the outdoor expansion valve (16), the outdoor heat exchanger (17), connected in the order of the refrigerant pipe in the order of the four-way switching valve (12), after the refrigerant pipe is further branched, each accumulator (18a, 18b) Are connected to the suction ports of the respective compressors (11a, 11b) through the air. Also,
The discharge port of the first compressor (11a) is connected to a liquid line between the outdoor expansion valve (16) and the outdoor heat exchanger (17) via a second solenoid valve (21) and a capillary tube (23). Is also connected.

-Operating operation- When the heating operation is performed in the third embodiment, the second solenoid valve (21) is set to "closed", and the first solenoid valve (20) is connected to both compressors (11a, 11b). When using the "open", the second compressor
When only (11b) is used, it is set to “closed”.

When the first solenoid valve (20) is set to "open", the refrigerant discharged from both compressors (11a, 11b) joins, then splits and flows to each indoor heat exchanger (13). Inflow. The refrigerant is
After being condensed in the indoor heat exchanger (13) and becoming a liquid refrigerant, and further passing through the indoor expansion valve (14), the outdoor expansion valve passes through the liquid receiver (41).
The pressure is reduced in (16) and flows into the outdoor heat exchanger (17). And
The liquid refrigerant evaporates by exchanging heat with outdoor air in the outdoor heat exchanger (17), and is sucked into the compressors (11a, 11b) via the four-way switching valve (12) and the accumulators (18a, 18b). .

When the first solenoid valve (20) is closed, the first compressor (11a) is stopped and only the second compressor (11b) is used. The circulation of the refrigerant and the resulting heat exchange are substantially the same as in the case where both compressors (11a, 11b) are used, and therefore the description is omitted here.

On the other hand, when frost forms on the outdoor heat exchanger (17), the first solenoid valve (20) is set to "closed", the second solenoid valve (21) is set to "open", and the first solenoid valve (21) is set to "open". The heating operation is continued by the second compressor (11b) while the defrost operation is performed by the compressor (11a).
At this time, control is performed so that the capacity of the first compressor (11a) is larger than the capacity of the second compressor (11b).

The gas refrigerant discharged from the second compressor (11b) heats the indoor air in the indoor heat exchanger (13), condenses, and flows out of the indoor heat exchanger (13). This liquid refrigerant is decompressed by the outdoor expansion valve (16) to become a gas-liquid two-phase refrigerant, and flows into the outdoor heat exchanger (17).

On the other hand, the gas discharged from the first compressor (11a) is decompressed by the capillary tube (23), and then discharged to the outdoor heat exchanger (17).
Flows into. At this time, while evaporating the two-phase refrigerant that has passed through the outdoor expansion valve (16), the outdoor heat exchanger (17) is also heated to remove frost attached to the outdoor heat exchanger (17).

Then, the refrigerant is kept in the gas phase in the outdoor heat exchanger.
(17), the four-way selector valve (12) and each accumulator (18
a, 18b) and is sucked into each compressor (11a, 11b).
Thereafter, when the defrosting of the outdoor heat exchanger (17) is completed, it becomes possible to perform the single-stage compression or the two-stage compression heating operation again.

-Effects of Embodiment 3 Also in Embodiment 3, since the heating operation can be continued during the defrost operation as in each of the above embodiments, the heating capacity does not decrease extremely, and the time required for the defrost operation Is relatively long, it is possible to prevent the indoor temperature from lowering.

[0091]

Fourth Embodiment An air conditioner (50) according to a fourth embodiment of the present invention is a system for performing two-stage compression, as shown in FIG. 5, in a bypass passage of an indoor heat exchanger (13). 51)
And an indoor heat exchanger (13) during defrost operation.
Is provided with a high-pressure holding means for closing in a state where is held at a high pressure.

Although the specific circuit configuration is almost the same as that of the second embodiment, in the fourth embodiment, the discharge pipe of the first compressor (11a) is directly connected only to the gas inlet of the gas-liquid separator (31). It is connected to the. The inside of the bypass passage (51) provided in parallel with the indoor unit (24), and the bypass passage (51) and the indoor heat exchanger (1
A shutoff valve (52, 53) is provided between the gas line and 3).

In this configuration, the high-pressure holding means includes:
It comprises an indoor expansion valve (14) constituted by an electronic expansion valve and a closing valve (53) constituted by an electromagnetic valve or the like.

-Operation- In the air conditioner of the fourth embodiment, the heating operation by two-stage compression and the heating operation by single-stage compression are performed in the same manner as the air conditioner of the second embodiment. At this time, the four-way switching valve (12) is set on the broken line side in the figure. Also, shut-off valve
(52) is closed and closure valve (53) is open.

On the other hand, in the fourth embodiment, the outdoor heat exchanger (1
7) When frost is formed, the indoor expansion valve
(14) and the closing valve (53) are closed to maintain the indoor heat exchanger (13) at a high pressure.

Then, the four-way switching valve (12) is switched to the solid line side in the drawing, and the defrost operation is started with the circulation direction of the refrigerant reversed. At this time, the first solenoid valve (20) and the closing valve (5
2) is set to "open" and the closing valve (53) is set to "closed". Further, the outdoor expansion valve (16) is controlled to fully open, the intermediate expansion valve (19) is controlled to a predetermined opening, and only the second compressor (11b) is operated.

Under this set condition, the high-temperature and high-pressure gas refrigerant discharged from the second compressor (11b) flows into the outdoor heat exchanger (17) to remove frost, is cooled, and is cooled. ). And, after the refrigerant passes through the gas-liquid separator (31),
The pressure is reduced by the intermediate expansion valve (19), and is sucked into the second compressor (11b) through the bypass passage (51).

At this time, since the indoor expansion valve (14) is closed, the refrigerant does not flow to the indoor heat exchanger (13). Therefore,
The defrost time is reduced as compared with the conventional positive cycle defrost.

According to the fourth embodiment, unlike the conventional positive cycle defrost (hot gas defrost), all the refrigerant circulating in the circuit is used for the defrost operation. Can be done in a short time. In addition, since the indoor heat exchanger (13) is maintained at a high pressure, that is, at a high temperature during defrosting, unlike the conventional reverse cycle defrost, cold draft does not occur, and a decrease in indoor temperature can be prevented.

-Modification of Fourth Embodiment- In the fourth embodiment, a system in which two compressors (11a, 11b) are connected in series has been described, but a system with one compressor may be used. In the fourth embodiment, the gas-liquid separator (3
Although it was configured as a system using 1), the gas-liquid separator (3
Instead of 1), the refrigerant heat exchanger (15) of Embodiment 1 or the like may be used.

[0101]

Fifth Embodiment An air conditioner (60) according to a fifth embodiment of the present invention, as shown in FIG. 6, is a system provided with a plurality of indoor heat exchangers (13a, 13b). Sometimes, the indoor heat exchanger (13a) for a living room is kept at high pressure, while the indoor heat exchanger (13b) for a non-living room such as a corridor or entrance.
Is used to perform reverse cycle defrosting.

The specific circuit configuration is almost the same as that of the air conditioner of the fourth embodiment. The difference is that instead of the closing valve (52) of the bypass passage (51) of the fourth embodiment, the indoor heat The indoor heat exchanger (13b) and the expansion valve (14b) form an indoor unit (24b) for a non-living room in that the heat exchanger (13b) and the expansion valve (14b) are connected. Have been.

-Operating operation- The air conditioner (60) of the fifth embodiment performs single-stage compression and two-stage compression operations almost in the same manner as in the fourth embodiment, so that a non-living room such as a living room or a corridor is provided. The inside can be heated. The circulation operation of the refrigerant at that time is almost the same as that of the fourth embodiment, and the description is omitted.

On the other hand, when frost forms on the outdoor heat exchanger (17), the indoor expansion valve (electronic expansion valve) (14a) and the closing valve (53) are set to "closed" in the heating operation, and For each indoor heat exchanger
After maintaining the pressure of (13a) at a high pressure, the flow direction of the refrigerant is switched to the reverse cycle by the four-way switching valve (12) to make the state shown by the solid line in the figure, and the defrost operation is performed.

At this time, the refrigerant discharged from the second compressor (11b) flows into the outdoor heat exchanger (17) and flows into the outdoor heat exchanger (17).
(17) is heated, and the outdoor expansion valve (16) and the gas-liquid separator (3
1), intermediate expansion valve (19) (outdoor expansion valve (16) and intermediate expansion valve (19)
Is controlled to fully open), and then the indoor expansion valve (1
The pressure is reduced in 4b) and flows into the non-residential indoor heat exchanger (13b). Since the indoor heat exchanger (13b) for the non-living room has been heated to a high temperature by the heating operation up to that time, the refrigerant evaporates and flows out of the indoor heat exchanger (13b). After that, four-way switching valve (12)
And a second compressor (11b) via a second accumulator (18b).
And the above operation is repeated.

As described above, in this embodiment, since the defrost is performed in the reverse cycle, the required time can be shorter than that in the fourth embodiment. In the living room, the indoor heat exchanger (13a)
Is kept at high pressure, so no cold draft occurs.

-Effects of Embodiment 5- According to Embodiment 5, defrosting can be performed in a shorter time, and the indoor unit (13a) has a high pressure (high temperature).
, The temperature in the room can be prevented from lowering.
In a corridor or entrance, cold draft occurs during defrost operation, and the temperature slightly decreases. However, since the room is not a living room, there is almost no problem of a decrease in comfort.

[0108]

Sixth Embodiment As shown in FIG. 7, the sixth embodiment of the present invention is an intermediate unit (2) for enabling a two-stage compression operation in an existing air conditioner (70) of a single-stage compression system. 7
2), the indoor heat exchanger (9
1) is maintained at a high pressure.

The circuit configuration of the air conditioner (70) of the sixth embodiment is as follows.

That is, the air conditioner (70) includes one outdoor unit (71) as a heat source unit, one power-up unit (72) as an intermediate unit, and a plurality of utilization units. It includes a plurality of indoor units (73) and is configured as a so-called multi-type. The power-up unit (72) can be added to an existing air conditioner having an outdoor unit (71) and an indoor unit (73).

A closed circuit refrigerant circuit (74) in which the circulation of the refrigerant is reversible is formed between the outdoor unit (71), the power up unit (72) and the indoor unit (73).

The outdoor unit (71) includes a low-stage compression mechanism (75), which is a main compression mechanism as a first compressor, and a four-way switching valve.
(76), a liquid receiver (77), an outdoor expansion valve (78), an outdoor heat exchanger (79) as a heat source side heat exchanger, and the like. These low-stage compression mechanism (75) and outdoor heat exchanger (79)
Are connected in order.

The low-stage compression mechanism (75) includes two compressors.
(81,82) are connected in parallel. The two compressors (81, 82) include, for example, an inverter-controlled variable-capacity compressor (81) and a constant-capacity compressor (82).

An oil separator (83) is connected to the discharge side of the variable displacement compressor (81), and a check valve (84) is connected to the discharge side of the constant displacement compressor (82). Have been. On the other hand, both compressors
An accumulator (85) is connected to the suction side of (81, 82).

A capillary tube is provided in the oil separator (83).
(86) is connected to the oil return pipe (87),
Is connected to the suction side of a variable capacity compressor (81). An oil equalizing pipe (89) having a capillary tube (88) is connected between the two compressors (81, 82).

The discharge side and the suction side of both compressors (81, 82) are connected to two ports of a four-way switching valve (76). The other two ports of the four-way switching valve (76) are connected to the power-up unit (72) and the outdoor heat exchanger (79).

The outdoor heat exchanger (79) is connected to a power-up unit (72) via an outdoor expansion valve (78) and a liquid receiver (77) in that order.

A line from one end of the outdoor heat exchanger (79) to the power-up unit (72) including the outdoor expansion valve (78) and the like is a liquid line (71L). In addition, the outdoor heat exchanger (79)
The line extending from the other end to the power-up unit (72) including the low-stage compression mechanism (75) is a gas line (71G).

The plurality of indoor units (73) are connected in parallel with each other and connected to a power-up unit (72). Each indoor unit (73) is an indoor expansion valve (90)
And the indoor heat exchanger (91), which is the use side heat exchanger, is a refrigerant pipe
(92) are connected in series.

The line from one end of the indoor heat exchanger (91) to the power-up unit (72) including the indoor expansion valve (90) is a liquid line (73L). A line from the other end of the indoor heat exchanger (91) to the power-up unit (72) is a gas line (73G).

The power-up unit (72) is for mainly performing the two-stage compression operation to increase the heating capacity, and is constituted by one single component. The power-up unit (72) includes a gas line (71G, 73G) and a liquid line between the outdoor unit (71) and the indoor unit (73).
(71L, 73L) at four locations.

The power-up unit (72) includes a high-stage compressor (93) as an auxiliary compressor as a second compressor, and includes a gas line (72G) and a liquid line (72L). I have.

The two ends of the liquid line (72L) are connected to the liquid line (71L) of the outdoor unit (71) and the liquid line of the indoor unit (73).
(73L). A liquid expansion valve (94) and a gas-liquid separator (95) are provided in the middle of the liquid line (72L). The liquid expansion valve (94) maintains the refrigerant pressure of the gas-liquid separator (95) at an intermediate pressure.

The two ends of the gas line (72G) are connected to the gas line (71G) of the outdoor unit (71) and the gas line (73G) of the indoor unit (73). The high-stage compressor (93) is provided in the middle of the gas line (72G).
The high-stage compressor (93) compresses the refrigerant discharged from the low-stage compression mechanism (75) of the outdoor unit (71) in two stages. The suction side of the high-stage compressor (93) is an outdoor unit (71)
Are connected via a gas expansion valve (96), the gas-liquid separator (95), and an accumulator (97). The discharge side of the high-stage compressor (93) is connected to the indoor unit (73).

A bypass passage (9) is provided in the gas line (72G).
8) is connected. One end of the bypass passage (98) is connected between the outdoor unit (71) and the gas expansion valve (96), and the other end of the bypass passage (98) is connected to the discharge port of the high-stage compressor (93). It is connected between the side and the indoor unit (73). And
The bypass passage (98) is provided with a closing valve (99).

The bypass passage (98) communicates with the single-stage compression operation to allow the refrigerant of the low-stage compression mechanism (75) to bypass the high-stage compressor (93) so as to perform two-stage compression. It is configured to be shut off during operation. That is, the power-up unit (72) is configured to switch between the single-stage compression operation and the two-stage compression operation.

Further, closing valves (100, 101) are provided on the discharge side and the suction side of the high-stage compressor (93) in the power-up unit (72), respectively. The closing valve (100, 101)
Is a blocking valve for blocking the refrigerant from flowing into the high-stage compressor (93). The closing valve (100, 101) is closed during single-stage compression operation,
The liquid refrigerant is prevented from accumulating in the stopped high-stage compressor (93). Conversely, the closing valves (100, 101) are opened during the two-stage compression operation.

The closing valve (100) on the discharge side of the high-stage compressor (93) may be a check valve.

Also, the high-stage compressor (93) and the gas-liquid separator (95)
Is connected to a liquid return passage (102). The liquid return passage (102) is provided with a closing valve (103).

The reason for providing the liquid return passage (102) is as follows. That is, even when the shut-off valves (100, 101) are provided on the discharge side and the suction side of the high-stage compressor (93) to prevent accumulation of the liquid refrigerant, the valve itself has a leak. Liquid refrigerant may accumulate. Therefore, the liquid refrigerant in the high-stage compressor (93) is sucked into the gas-liquid separator (95) of the intermediate pressure, so that the shortage of the refrigerant is reliably prevented.

-Operation- Next, the cooling and heating operation of the air conditioner (70) will be described.

First, during the cooling operation of the air conditioner (70), the single-stage compression operation is performed by driving the low-stage compression mechanism (75) and stopping the high-stage compressor (93). In this case, the four-way switching valve (76) switches to the solid line side in FIG. Also, a closing valve (99) of the bypass passage (98) in the power-up unit (72)
Is opened and the gas expansion valve (96) is closed, while the liquid expansion valve (94) of the power-up unit (72) is fully opened.

In this state, the refrigerant compressed by the low-stage compression mechanism (75) of the outdoor unit (71) is supplied to the four-way switching valve (76).
, And flows into the outdoor heat exchanger (79) to condense. The condensed liquid refrigerant passes through the liquid receiver (77) and is supplied to the power-up unit (7).
2), and then to the indoor unit (73) via the gas-liquid separator (95) and the liquid expansion valve (94). Further, the pressure of the liquid refrigerant is reduced by the indoor expansion valve (90), flows into the indoor heat exchanger (91), and evaporates.

Thereafter, the evaporated gas refrigerant flows to the power-up unit (72), flows through the bypass passage (98), and bypasses the high-stage compressor (93). The gas refrigerant flows to the outdoor unit (71) and passes through the four-way switching valve (76) to the low-stage compression mechanism.
Return to (75). This circulation operation is repeated to cool the room.

Next, a case where the heating load is large in the heating operation will be described.

During the heating operation, the two-stage compression operation is performed by driving both the low-stage compression mechanism (75) and the high-stage compressor (93). In this case, the four-way switching valve (76) switches to the broken line side in FIG.

In addition, the closing valve (99) of the bypass passage (98) in the power-up unit (72) is closed, and the gas expansion valve (96) is closed.
Is open. Further, the liquid expansion valve (94) is set to a predetermined opening so as to generate an intermediate-pressure refrigerant.

In this state, the low-pressure refrigerant is supplied to both compressors (81, 82) of the low-stage compression mechanism (75) in the outdoor unit (71).
Is compressed in one stage. The one-stage compressed refrigerant flows to the power-up unit (72) via the four-way switching valve (76).
This refrigerant flows into the gas-liquid separator (95) via the gas expansion valve (96). In the gas-liquid separator (95), the refrigerant flows into the high-stage compressor (93) after being cooled by a liquid refrigerant described later.

The refrigerant that has been subjected to the two-stage compression in the high-stage compressor (93) flows to the indoor unit (73), and the indoor heat exchanger (9)
In 1), it exchanges heat with indoor air and condenses. The condensed liquid refrigerant flows to the power-up unit (72), is reduced to an intermediate pressure by the liquid expansion valve (94), and flows into the gas-liquid separator (95). In the gas-liquid separator (95), as described above, the refrigerant flowing from the low-stage compression mechanism (75) to the high-stage compressor (93) is cooled.

On the other hand, the liquid refrigerant of the gas-liquid separator (95) flows to the outdoor unit (71) and passes through the liquid receiver (77) to the outdoor expansion valve (7).
The pressure is reduced in 8). The liquid refrigerant flows into the outdoor heat exchanger (79) and evaporates.

Thereafter, the evaporated gas refrigerant is supplied to the four-way switching valve.
After (76), the process returns to the low-stage compression mechanism (75). This circulation operation is repeated to heat the room.

Next, a case where the heating load is small in the above-described heating operation will be described.

During the heating operation, the single-stage compression operation is performed by driving the low-stage compression mechanism (75) and stopping the high-stage compressor (93). In this case, the four-way switching valve (76) switches to the broken line side in FIG. Further, the closing valve (99) of the bypass passage (98) in the power-up unit (72) is opened and the gas expansion valve (96) is closed, while the liquid expansion valve (94) of the power-up unit (72) is closed.
Is fully open.

In this state, the refrigerant compressed by the low-stage compression mechanism (75) of the outdoor unit (71) is supplied to the four-way switching valve (76).
Through the power-up unit (72). The refrigerant is
It flows through the bypass passage (98) to bypass the high-stage compressor (93).

Thereafter, the refrigerant flows into the indoor unit (73) and is condensed in the indoor heat exchanger (91). The condensed liquid refrigerant flows to the power-up unit (72), and the liquid expansion valve (94)
And, it flows to the outdoor unit (71) via the gas-liquid separator (95).
Further, the liquid refrigerant passes through a liquid receiver (77) and an outdoor expansion valve (78).
, And flows into the outdoor heat exchanger (79) to evaporate.

After that, the evaporated gas refrigerant is supplied to the four-way switching valve.
The flow returns to the low-stage compression mechanism (75) via (76), and the circulation operation is repeated to heat the room.

Next, when frost is formed on the outdoor heat exchanger (79) by performing the heating operation by the two-stage compression or the single-stage compression, the defrost operation is performed. When performing this defrost operation, first, during the heating operation, the closing valves (99, 100, 101) are closed following the indoor expansion valve (90), and the indoor heat exchanger (91) is maintained at a high pressure. Specifically, when performing two-stage compression, close the close valve (100) following the indoor expansion valve (90), stop the high-stage compressor (93), and close the close valves (99, 101). . When single-stage compression is performed, the closing valve (99) is closed following the indoor expansion valve (90).

Then, the four-way switching valve (76) is switched to the solid line side in the figure to circulate the refrigerant of the low-stage compression mechanism (75). That is, the refrigerant discharged from the low-stage compression mechanism (75) flows to the outdoor heat exchanger (79) and heats the outdoor heat exchanger (79).
The refrigerant flowing out of the outdoor heat exchanger (79) passes through the outdoor expansion valve (78), flows through the liquid receiver (77), flows into the power-up unit (72), and flows into the gas-liquid separator (95). Then, the refrigerant flows out of the gas-liquid separator (95), passes through the gas expansion valve (96), decompresses and returns to the outdoor unit (71), and the accumulator (85)
Through the lower stage compression mechanism (75). By repeating this circulation of the refrigerant, frost attached to the outdoor heat exchanger is removed.

-Effects of Sixth Embodiment- As described above, in the sixth embodiment as well, each of the closing valves (99, 100, 101) and the indoor expansion valve (90) during the defrost operation (these components constitute high-pressure holding means). To keep the indoor heat exchanger (91) at a high pressure to prevent refrigerant from circulating through the indoor heat exchanger (91), so that defrosting of the outdoor heat exchanger (79) can be performed in a relatively short time. It can be performed, and no cold draft occurs in the room.

The power-up unit (72) is
It can be easily added to an existing air conditioner.
As a result, it is possible to easily increase the heating capacity and the like. Further, since the single-stage compression operation and the two-stage compression operation can be switched, a normal heating operation can be performed even when the power-up unit (72) fails. As a result, the reliability can be improved.

The power-up unit (72) is provided with two closing valves (100, 101). The closing valves (100, 101) are opened during the two-stage compression operation, and are closed during the single-stage compression operation to stop the liquid refrigerant. The high-stage compressor (93) does not accumulate in the high-stage compressor (93), so that the accumulation of the liquid refrigerant in the high-stage compressor (93) can be reliably prevented, and the shortage of the refrigerant is surely prevented. Can be.

Further, since the liquid return passage (102) is provided, the shut-off valves (100, 101) provided on the discharge side and the suction side of the high-stage compressor (93) leak, and the liquid refrigerant is slightly discharged. Even if water accumulates, the liquid refrigerant of the high-stage compressor (93) is sucked into the gas-liquid separator (95) at the intermediate pressure, and shortage of the refrigerant can be reliably prevented.

-Variation of Sixth Embodiment- In the sixth embodiment, the power-up unit (72)
Although the configuration in which the indoor heat exchanger (91) is maintained at a high pressure during the defrost operation in the air conditioning system using the system described above, the system using the power-up unit (72) as in the sixth embodiment can be used in the first embodiment. For example, the circuit configuration may be such that the auxiliary compressor (93) of the power-up unit (72) is used for the heating operation and the compressor (75) of the heat source unit (71) is used for the defrost operation. Embodiments 7 to 11 will be described below as examples configured in this manner.

[0154]

Seventh Embodiment A seventh embodiment of the present invention is a conceptual diagram of an air conditioner (110) having an intermediate unit for performing two-stage compression between an outdoor unit and an indoor unit. As shown in FIG. 8, the refrigerant at the lower stage and the refrigerant at the higher stage are mixed in the gas-liquid separator (120) and heated by the residual heat while being mixed with the indoor heat exchanger (122) and the outdoor heat exchanger (114). ), The heating operation and the defrost operation can be performed simultaneously.

The specific circuit configuration of the air conditioner (110) is as follows.

That is, as shown in FIG. 9, the outdoor unit (111) comprises a variable-capacity low-stage compressor as a first compressor.
(112), a first four-way switching valve (113), an outdoor heat exchanger (114), and an outdoor expansion valve (115). Intermediate unit (116)
Includes a high-stage compressor (117) as a second compressor, a second four-way switching valve (118), an intermediate expansion valve (119), and a gas-liquid separator (120). The indoor unit (121) includes an indoor heat exchanger (122) and an indoor expansion valve (123). And
These devices are connected in order by a refrigerant pipe (124). The refrigerant pipe (124) is connected to each unit (111, 1
16,121) are connected by a pipe joint (125).

More specifically, the first compressor (112) and the second compressor (117) have a first four-way switching valve (113) and a second four-way switching valve (118) on the suction side and the discharge side, respectively. Are connected to two ports. First four-way switching valve (113) and second four-way switching valve
(118) is a first four-way switching valve with one port connected
The other port of (113) is connected to the outdoor heat exchanger (114), and the other port of the second four-way switching valve (118) is connected to the indoor heat exchanger.
(122). Then, each four-way switching valve (113, 1
18) is switched to the state shown by the solid line in FIG.
The gas refrigerant discharged from the first compressor (112) is supplied to both four-way switching valves (113, 1
18) and is sucked into the second compressor (117). As described above, the gas line (124G) between the outdoor heat exchanger (114) and the indoor heat exchanger (122) is configured.

An indoor heat exchanger (122) and an outdoor heat exchanger (114)
In the liquid line (124L) between the indoor expansion valve (123), the intermediate expansion valve (119), the gas-liquid separator (120), and the outdoor expansion valve ( 115) is provided.
The gas outlet of the gas-liquid separator (115) is connected to the second compressor (11).
The suction pipe (7) is connected between the two four-way switching valves (113, 118) to form an injection passage (126). The injection passage (126) is provided with an on-off valve (127) such as a solenoid valve.

Further, the gas line (124G) between the two four-way switching valves (113, 118), the second four-way switching valve (118) and the second compressor
A one-way passage (128) is connected to the suction pipe between (117). The one-way passage (128) is provided with an overpressure release valve (129) composed of a check valve. When the second compressor (117) is stopped during single-stage compression, the second compressor (117) is cooled to prevent the second compressor (117) from cooling and accumulating liquid refrigerant. Is heated by a heating means such as a crankcase heater (130) to release the gas refrigerant to an overpressure release valve (129).
I am trying to pull it out.

-Operating operation- Next, the operating operation of the air conditioner (110) will be described.

First, the operation when the heating operation is performed by the two-stage compression will be described. At this time, each four-way switching valve (11
3,118) is set to the state shown by the solid line in FIG. Further, the indoor expansion valve (123) is set to fully open, the intermediate expansion valve (119) is set to an opening degree to reduce the high pressure refrigerant to a predetermined intermediate pressure, and the outdoor expansion valve (115) is set to the intermediate pressure. The opening is set so as to reduce the pressure of the refrigerant to a predetermined low pressure. The above setting is for gas injection, and at this time, the on-off valve (127) of the injection passage (126) is open.

Then, the low-pressure refrigerant is compressed in one stage by the first compressor (112) and discharged, and the discharged gas is discharged to the second compressor (1).
17) Two-stage compression is performed. The gas refrigerant discharged from the second compressor (117) is supplied to the indoor heat exchanger (12) through the second four-way switching valve (118).
2), and heat exchanges with room air to heat the room air. The heated indoor air is blown into the room by an indoor fan (not shown), and warm air is supplied to the room.

The refrigerant condensed by the heat exchange in the indoor heat exchanger (122) passes through the indoor expansion valve (123), and partially expands in the intermediate expansion valve (119) to become a two-phase refrigerant. Gas-liquid separator
(120). Then, the liquid refrigerant and the gas refrigerant are separated by the gas-liquid separator (120), and the liquid refrigerant flows out of the gas-liquid separator (120), is decompressed by the outdoor expansion valve (115), and is discharged from the outdoor heat exchanger (1).
14). Then, in the outdoor heat exchanger (114), the refrigerant is heated by exchanging heat with outdoor air, is heated, changes its phase into a gas refrigerant, passes through the first four-way switching valve (113), and passes through the first compressor (112).
Inhaled.

On the other hand, the gas refrigerant in the gas-liquid separator (120)
It flows out of the gas outlet, merges with the gas refrigerant discharged from the first compressor (112) through the injection passage (127), and is sucked into the second compressor (117). Therefore, the indoor heat exchanger (12
2) Since the amount of refrigerant flowing through increases, the heating capacity can be increased. When gas injection is not performed, the intermediate expansion valve (119) is set to fully open, and the open / close valve (127) of the injection passage (126) is set to "closed".

Next, a single-stage compression heating operation will be described. At this time, the first compressor (112) is operated to drive the second compressor (112).
(117) is stopped, the first four-way switching valve (113) is set to the state shown by the solid line in FIG. 9, and the second four-way switching valve (118) is set to the state shown by the broken line. Then, the indoor expansion valve (123) and the intermediate expansion valve (119) are fully opened, and the solenoid valve (12) in the injection passage (126) is opened.
7) is closed. By doing so, the first compressor (112)
The first four-way switching valve (113) and the second four-way switching valve
(118) and flows into the indoor heat exchanger (122) to heat the indoor air in the indoor heat exchanger (122). The refrigerant condensed at that time is supplied to the indoor expansion valve (123) and the intermediate expansion valve.
(119) and the gas-liquid separator (120).
The pressure is reduced in 5) and flows into the outdoor heat exchanger (114). In the outdoor heat exchanger (114), the refrigerant is heated, changes into a gas phase, and is sucked into the first compressor (112). The single-stage compression heating operation is performed by repeating the above cycle.

When frost is formed on the outdoor heat exchanger (114) by performing the heating operation in the two-stage compression or the single-stage compression, the defrost operation is performed. During the defrost operation, both compressors (112, 117) are operated in a state where the capacity of the first compressor (112) is larger than the capacity of the second compressor (117), and the first four-way switching valve (113) is set in FIG.
The second four-way switching valve (118) is set to the state shown by the solid line. The indoor expansion valve (123) is set to fully open, the opening of the intermediate expansion valve (119) and the outdoor expansion valve (115) is controlled so as to reduce the high-pressure liquid refrigerant to a predetermined low pressure, and the injection passage ( The solenoid valve (127) of (126) is set to "open".

With the above setting, the gas discharged from the first compressor (112) is supplied to the outdoor heat exchanger (11) through the first four-way switching valve (113).
4) to heat the outdoor heat exchanger (114). At this time, the outdoor fan (not shown) is stopped, and the refrigerant is cooled somewhat and flows out of the outdoor heat exchanger (114), and the outdoor expansion valve (1
The pressure is reduced in step 15) and flows into the gas-liquid separator in a nearly gas phase.

On the other hand, the gas discharged from the second compressor (117) flows into the indoor heat exchanger (122) via the second four-way switching valve (118). At this time, the indoor fan (not shown) is rotating,
Heat exchange between the refrigerant and room air is performed. Therefore, the blowing of warm air into the room is continued, and the refrigerant condenses and flows out of the indoor heat exchanger (122). The refrigerant is then supplied to the intermediate expansion valve (1
19) The pressure is reduced to a gas-liquid two-phase state by the gas-liquid separator (120).
And mixes with the lower stage refrigerant.

This refrigerant is heated by the residual heat of the low-stage refrigerant in the gas-liquid separator (120). And the gas-liquid separator (1
20), the gas refrigerant flows out and splits into the lower stage and the higher stage,
It is sucked into each compressor (112,117). Each compressor (112,117)
The refrigerant sucked in is recompressed and discharged again, and the above cycle is repeated on the outside and the inside of the room.

Note that the cooling operation is performed by operating only the first compressor (112) and switching the two-way switching valves (113, 118) to the state shown by the broken line in FIG. At this time, the outdoor expansion valve (115) and the intermediate expansion valve (119) are set to fully open, and the opening degree of the indoor expansion valve (123) is controlled so as to reduce the high-pressure refrigerant to a predetermined low pressure. Also, the solenoid valve (127) of the injection passage (126)
Is closed. With the above settings, the refrigerant is supplied to the first compressor (1
12), first four-way switching valve (113), outdoor heat exchanger (114), outdoor expansion valve (115), gas-liquid separator (120), intermediate expansion valve (119)
, The indoor expansion valve (123), the indoor heat exchanger (122), the second four-way switching valve (118), and the cool air blows into the room when heat is exchanged in the indoor heat exchanger (122). Is done.

When the second compressor (117) is stopped, for example, during heating operation or cooling operation by single-stage compression,
By heating the second compressor (117) with a heating means (130) such as a crankcase heater and removing the gas refrigerant from the overpressure release valve (129), the liquid refrigerant accumulates in the second compressor (117). Is prevented.

-Effects of the Seventh Embodiment- In the configuration of the seventh embodiment as well, the outdoor heat exchanger (114) is used by the first compressor (112) while the heating operation is continued by the second compressor (117).
Can be defrosted, so that a decrease in heating capacity during defrost can be suppressed. Therefore, it is possible to prevent the room temperature from decreasing during the defrost operation.

[0173]

Eighth Embodiment An air conditioner (140) according to an eighth embodiment of the present invention, as shown in FIG. 10, includes a second compressor in the refrigerant circuit of the air conditioner (110) of the seventh embodiment. An unload passage (141) for returning the discharged gas refrigerant of (117) to the suction side is provided. An opening / closing valve (142) such as a solenoid valve is provided in the unload passage (141).
1) is configured to be able to control opening and closing. The other specific circuit configuration is the same as that of the seventh embodiment, and the description is omitted.

-Operation- In the above configuration, the solenoid valve (142) of the unload passage (141) is closed during the heating operation or the cooling operation, and the seventh embodiment is performed.
In the same manner as described above, the refrigerant circulates through the circuit to blow out warm air or cold air into the room.

On the other hand, at the time of defrost operation, the solenoid valves (142) of the unload passage (141) are opened, and the other compressors (112, 117) are operated with the same settings as in the seventh embodiment. In this way, the refrigerant on the first compressor (112) side and the refrigerant on the second compressor (117) side join in the gas-liquid separator (120) while the indoor heat exchange with the outdoor heat exchanger (114) side. Tableware (122)
The operation of circulating on the side is performed in the same manner as in the seventh embodiment,
Since a part of the refrigerant discharged from the second compressor (117) bypasses from the discharge side to the suction side, the low pressure of the second compressor (117) increases.

Therefore, the low pressure on the first compressor (112) side becomes lower than the low pressure on the second compressor (117) side, and the gas refrigerant flowing out of the gas-liquid separator (120) is 1 compressor (1
12) More inhaled. Therefore, the outdoor heat exchanger
(114) The circulation amount of the refrigerant increases, and the defrosting time can be reduced as compared with the seventh embodiment.

-Effects of Eighth Embodiment- As described above, according to the eighth embodiment, in addition to obtaining the same effects as those of the seventh embodiment, the time of the defrost operation can be shortened. The lowering of the room temperature can be more reliably prevented.

[0178]

Ninth Embodiment An air conditioner (150) according to a ninth embodiment of the present invention includes a first bypass passage (151) in a refrigerant circuit of the air conditioner of the seventh embodiment as shown in FIG. And a second bypass passage (152).

The first bypass passage (151) is connected to the outdoor heat exchanger.
(114) and a liquid line (124L) between the outdoor expansion valve (115),
A part of the refrigerant, which is connected to the gas line (124G) on the suction side of the first compressor (112) and flows out of the outdoor heat exchanger (114) during the defrost operation, is discharged from the upstream side of the outdoor expansion valve (115) to the first side. Compressor
It is configured to return to the suction side of (112). The second bypass passage (152) has a liquid line (124L) between the indoor expansion valve (123) and the intermediate expansion valve (119) and a gas line (124G) on the suction side of the second compressor (117). Connected to the indoor heat exchanger (1
Part of the refrigerant flowing out of the second compressor (117) is returned from the upstream side of the intermediate expansion valve (119) to the suction side of the second compressor (117).

Each of the bypass passages (151, 152) is provided with a flow control mechanism (153, 154) for adjusting the flow rate of the refrigerant. Each of the flow control mechanisms (153, 154) is configured by combining an electromagnetic valve and a capillary tube,
Or it can be constituted by an electric expansion valve.

-Operation- In the above configuration, during the heating operation or the cooling operation, the flow control mechanisms (153, 154) of the bypass passages (151, 152) are closed, and the refrigerant is circuited with the same settings as in the seventh and eighth embodiments. The hot air or cold air is blown into the room by circulating through the inside.

On the other hand, at the time of defrost operation, the flow control mechanisms (153, 154) of each bypass passage (151, 152) are opened, and the other valves are set in the same manner as in the seventh embodiment so that both compressors are set.
(112,117) is operated. In this way, the refrigerant on the first compressor (112) side and the refrigerant on the second compressor (117) side join in the gas-liquid separator (120) while the indoor heat exchange with the outdoor heat exchanger (114) side. The operation of circulating on the side of the compressor (122) is performed in the same manner as in the seventh embodiment, while the operation of the outdoor expansion valve (11) is performed on the first compressor side (112).
Part of the refrigerant bypasses to the suction side before step 5), and part of the refrigerant bypasses to the suction side on the second compressor (117) side before the intermediate expansion valve (119).

On the second compressor (117) side, an indoor fan (not shown) is rotating, so that the liquid refrigerant condensed in the indoor heat exchanger (122) bypasses to the suction side. The pressure is reduced in the control mechanism (154), a part of the gas is evaporated, and further mixed with the gas refrigerant from the gas-liquid separator (120) to evaporate. It becomes a refrigerant and is discharged to the indoor heat exchanger (122). On the first compressor (112) side, an outdoor fan (not shown) is stopped, so that the gas refrigerant somewhat cooled by the outdoor heat exchanger (114) bypasses to the suction side. This refrigerant is depressurized by the flow control mechanism (153), mixed with the gas refrigerant from the gas-liquid separator (120), compressed by the first compressor (112), and sent to the indoor heat exchanger (114). Discharged. For this reason, the circulation amount of the refrigerant increases both on the outdoor side and the indoor side, and the stagnation of the liquid refrigerant in the gas-liquid separator (120) can be suppressed.

-Effects of Embodiment 9- As described above, according to Embodiment 9, the gas-liquid separator (120)
This prevents the refrigerant from gradually accumulating in the outdoor heat exchanger (114) and the indoor heat exchanger (122), as compared with the case where the bypass passages (151, 152) are not provided. The amount of circulation increases. Therefore, compared to the seventh embodiment,
Since the time for the defrost operation can be shortened and the decrease in the heating capacity during that period can be suppressed, the decrease in the room temperature during the defrost operation can be more reliably prevented.

-Modification 1 of Embodiment 9- FIG. 12 shows a modification of the ninth embodiment. In this example, the connection position of each bypass passage (151, 152) is different from that of the ninth embodiment. That is, the first bypass passage (151)
Are a liquid line (124L) between the outdoor expansion valve (115) and the gas-liquid separator (120), and a gas line (1) on the suction side of the first compressor (112).
24G), and a second bypass passage (152) is connected to a liquid line (124L) between the intermediate expansion valve (119) and the gas-liquid separator (120).
And a gas line (124G) on the suction side of the second compressor (117). The other configuration is the same as that of the ninth embodiment. With this configuration, since the refrigerant after passing through each expansion valve (115, 119) has an intermediate pressure, the flow control mechanism (153, 1)
In 54), if the pressure of the refrigerant is reduced from the intermediate pressure to a low pressure, the same effect as in the ninth embodiment can be obtained.

-Variation 2 of Embodiment 9 In the examples of FIGS. 11 and 12, the bypass passages (151, 152) are provided both on the outdoor side and the indoor side, but the second bypass passage (152) on the indoor side is provided. , And only the first bypass passage (151) on the outdoor side may be provided. With this configuration, the defrost time can be reduced in the seventh embodiment, and as a result, a decrease in room temperature can be reliably suppressed.

Conversely, a configuration may be adopted in which only the second bypass passage (152) on the indoor side is provided without providing the first bypass passage (151) on the outdoor side. With this configuration, it is possible to improve the heating capacity in the seventh embodiment. As a result, even if the defrost operation time becomes slightly longer, the effect of reliably preventing the room temperature from decreasing during the defrost operation can be obtained. is there.

[0188]

Embodiment 10 In the refrigerant circuit according to Embodiment 10 of the present invention, a refrigerant heater (refrigerant heating means) (refrigerant heating means) is provided in the gas-liquid separator (120) as shown in FIG. 120
This is an example in which a) is provided. This refrigerant heater (120a) is provided in a liquid line (124L) connected to the gas-liquid separator (120). Other circuit configurations are the same as in the seventh embodiment, and the heating operation and the cooling operation are performed in the same manner as in the seventh embodiment. Also,
The defrost operation is performed in the same manner as in the seventh embodiment except that the refrigerant flowing into the gas-liquid separator (120) is heated by the refrigerant heater (120a). The refrigerant heater (120a) may be an arbitrary heater, such as an electric resistance heating type heater or an electromagnetic induction heating type heater, as long as the refrigerant can be heated through a pipe. Good.

-Effect of Embodiment 10- By using the refrigerant heater (120a), the refrigerant flowing into the gas-liquid separator (120) at the time of defrosting is heated to increase the dryness of the refrigerant, thereby improving the gas-liquid separation. The stagnation of the liquid refrigerant in the vessel (120) can be prevented. Therefore, compared to the seventh embodiment, it is possible to continue the operation of simultaneously performing the defrosting and heating of the outdoor heat exchanger (114) for a long time, and it is possible to sufficiently perform the defrosting while heating. Become. For this reason, in the configuration of the seventh embodiment, for example, even when the defrost operation needs to be performed relatively frequently with a small amount of frost, the execution frequency of the defrost operation can be reduced in the tenth embodiment.

-Modification of Embodiment 10- As shown in FIG. 13 (b), the refrigerant heater (120a) is configured to heat the refrigerant via the container of the gas-liquid separator (120). Is also good. Also in this case, an arbitrary heater such as an electric resistance heating type heater or an electromagnetic induction heating type heater can be appropriately used as the refrigerant heater (120). By heating the refrigerant in the gas-liquid separator (120) during the defrost operation, the same effect as in the example of FIG. 13A can be obtained. In addition, the refrigerant heater (120a) is connected to the gas-liquid separator (1
Not only outside the container of 20), but also inside the container.

As shown in FIG. 13 (c), a gas-liquid separator (120) is provided instead of the refrigerant heater (120a) or the refrigerant heater (120a) shown in FIG. 13 (a). At the same time, a refrigerant warmer (refrigerant warming means) (120b) may be provided. In this case, when the defrost operation and the heating operation are simultaneously performed in the circuit of the seventh embodiment, the gas-liquid separator (120)
The internal refrigerant can be heated by the residual heat for a long time. As a result, defrosting and heating of the outdoor heat exchanger (114) can be simultaneously continued for a longer time than in the seventh embodiment, and a decrease in room temperature during defrost operation can be suppressed.

[0192]

Eleventh Embodiment In the eleventh embodiment of the present invention shown in FIG. 14, an intermediate unit (116) for performing two-stage compression is an outdoor unit (111) and an indoor unit (121). In the air conditioner (160) provided between (1) and (2), the intermediate unit (116) is configured differently from the seventh embodiment. Also in this configuration, the heating operation and the defrost operation can be performed simultaneously by circulating the refrigerant on the indoor unit (121) side and the outdoor unit (111) side while mixing the low stage refrigerant and the high stage refrigerant. Like that.

The specific circuit configuration of the air conditioner (160) is as follows.

That is, the variable capacity first compressor (112)
The suction side and the discharge side are connected to two ports of the first four-way switching valve (113). The other port of the first four-way switching valve (113) is connected to the outdoor heat exchanger (114), and the other port is connected to one port of the second four-way switching valve (118). I have. The other four ports of the second four-way switching valve (118) are connected to the suction side of the second compressor (117) from the gas-liquid separator (120) and the discharge side of the second compressor (117). Indoor heat exchanger (122)
And connected to. And each four-way switching valve (113, 118)
Is switched to the state shown by the solid line in FIG.
The gas refrigerant discharged from the compressor (112) is supplied to each four-way switching valve (113, 118).
The gas is sucked into the second compressor (117) via the gas and liquid separator (120). From the above, the outdoor heat exchanger (1
A gas line (124G) is formed between the indoor heat exchanger (122) and the indoor heat exchanger (122).

An indoor heat exchanger (122) and an outdoor heat exchanger (114)
And the liquid line (124L) from the indoor heat exchanger (122) to the gas inlet of the gas-liquid separator (120) via the indoor expansion valve (123) and the intermediate expansion valve (119) in this order. In addition, the liquid outlet of the gas-liquid separator (120) is connected to the check valve (161) and the outdoor expansion valve (11).
5) is connected to the outdoor heat exchanger (114). The liquid line (124L) is located between the indoor expansion valve (123) and the intermediate expansion valve (119), the check valve (161) and the outdoor expansion valve (1).
15) are connected via a communication passage (163) provided with an on-off valve (162) such as a solenoid valve.

As in Embodiment 7, when the second compressor (117) is stopped during single-stage compression, the second compressor (1) is stopped.
17), the liquid refrigerant is heated by a crankcase heater or the like of the second compressor (117) to separate the gas refrigerant from the gas-liquid separator (120). )
I try to pull it out.

-Operational Operation- Next, the operational operation of the air conditioner (160) will be described.

First, the operation when the heating operation is performed by the two-stage compression will be described. At this time, each four-way switching valve (11
3,118) is set to the state shown by the solid line in the figure. Further, the indoor expansion valve (123) is set to fully open, the intermediate expansion valve (119) is set to an opening degree to reduce the high pressure refrigerant to a predetermined intermediate pressure, and the outdoor expansion valve (115) is set to the intermediate pressure. The opening is set so as to reduce the pressure of the refrigerant to a predetermined low pressure. In addition, communication passage (163)
Of the solenoid valve (162) is closed.

Then, the low-pressure refrigerant is compressed in one stage by the first compressor (112) and discharged, and the discharged gas is discharged to the gas-liquid separator (1).
20), is sucked into the second compressor (117), and is compressed in two stages. The gas refrigerant discharged from the second compressor (117) flows into the indoor heat exchanger (122) via the second four-way switching valve (118) and exchanges heat with the indoor air to heat the indoor air. The heated indoor air is blown into the room by an indoor fan (not shown), and warm air is supplied to the room.

The refrigerant condensed by the heat exchange in the indoor heat exchanger (122) passes through the indoor expansion valve (123), and partially expands in the intermediate expansion valve (119) to become a two-phase refrigerant. Gas-liquid separator
(120). Then, the liquid refrigerant and the gas refrigerant are separated by the gas-liquid separator (120), and the liquid refrigerant flows out of the gas-liquid separator (120), is decompressed by the outdoor expansion valve (115), and is discharged from the outdoor heat exchanger (1).
14). Then, in the outdoor heat exchanger (114), the refrigerant is heated by exchanging heat with outdoor air, is heated, changes its phase into a gas refrigerant, passes through the first four-way switching valve (113), and passes through the first compressor (112).
Inhaled.

On the other hand, the gas refrigerant in the gas-liquid separator (120) merges with the gas refrigerant discharged from the first compressor (112), and
Inhaled at (117). Therefore, the indoor heat exchanger (122)
Since the amount of refrigerant flowing through increases, a high heating capacity can be obtained.

Next, a single-stage compression heating operation will be described. At this time, the first compressor (112) is operated to drive the second compressor (112).
(117) is stopped, the first four-way switching valve (113) is set to the state shown by the solid line in the figure, and the second four-way switching valve (118) is set to the state shown by the broken line in the figure. Then, the indoor expansion valve (123) is controlled to be fully opened, the intermediate expansion valve (119) is controlled to be fully closed, and the outdoor expansion valve (115) is controlled so as to reduce the pressure of the high-pressure refrigerant to a predetermined low pressure. Also, the solenoid valve (162) of the communication passage (163) is opened.

In this case, the gas discharged from the first compressor (112) is supplied to the first four-way switching valve (113) and the second four-way switching valve (11).
8) and flows into the indoor heat exchanger (122) to heat the indoor air in the indoor heat exchanger (122). The refrigerant condensed at that time is supplied to the indoor expansion valve (123) and the communication passage.
After passing through (163), the pressure is reduced by the outdoor expansion valve (115) and flows into the outdoor heat exchanger (114). The refrigerant is heated by the outdoor heat exchanger (114), changes into a gas phase, and is sucked into the first compressor (112). The single-stage compression heating operation is performed by repeating the above cycle.

As described above, when the heating operation in the two-stage compression or the single-stage compression is performed and frost is formed on the outdoor heat exchanger (114), the defrost operation is performed. During defrost operation, both compressors (112, 117) are operated in a state where the amount is larger than the capacity of the second compressor (117) as in the first compressor (112), and the first four-way switching valve (113) is The second four-way switching valve (118) is set to the state shown by the solid line in FIG. The indoor expansion valve (12
3) and the outdoor expansion valve (115) are set to fully open and the communication passage
The opening of the intermediate expansion valve (119) is controlled so that the high pressure liquid refrigerant is reduced to a predetermined low pressure while the solenoid valve (162) of (163) is opened.

With the above setting, the gas discharged from the first compressor (112) is supplied to the outdoor heat exchanger (11) through the first four-way switching valve (113).
4) to heat the outdoor heat exchanger (114). At this time, the outdoor fan (not shown) is stopped, the refrigerant is cooled somewhat, flows out of the outdoor heat exchanger (114), further passes through the communication passage (163) from the outdoor expansion valve (115), and is The expansion valve (119) is reached.

On the other hand, the gas discharged from the second compressor (117) flows into the indoor heat exchanger (122) via the second four-way switching valve (118). At this time, the indoor fan (not shown) is rotating,
Heat exchange between the refrigerant and room air is performed. Therefore, the blowing of warm air into the room is continued, and the refrigerant condenses and flows out of the indoor heat exchanger (122). After passing through the indoor expansion valve (123), the refrigerant merges with the refrigerant from the first compressor (112) and is decompressed by the intermediate expansion valve (119). 120).

This refrigerant is partially heated to the first compressor (112) side while being heated by the residual heat of the low-stage refrigerant, and another part is transmitted to the second compressor via the gas-liquid separator (120). Machine (117). The refrigerant drawn into each of the compressors (112, 117) is compressed again and discharged, and the above-described cycle is repeatedly performed on the outdoor side and the indoor side, so that the defrost operation is performed while the heating operation is continued.

The cooling operation is performed by operating only the first compressor (112) and switching the two-way switching valves (113, 118) to the state shown by the broken lines in the figure. At this time, the outdoor expansion valve (115) is set to fully open, and the opening of the indoor expansion valve (123) is controlled so as to reduce the high-pressure refrigerant to a predetermined low pressure. In addition, access passage (1
The solenoid valve (162) of (63) is opened, and the intermediate expansion valve (119) is closed. With the above setting, the refrigerant is supplied to the first compressor (112).
, First four-way switching valve (113), outdoor heat exchanger (114), outdoor expansion valve (115), communication passage (163), indoor expansion valve (123), indoor heat exchanger (122), second fourth Cool air is blown into the room by circulating in the order of the road switching valve (118) and the first four-way switching valve (113).

-Effects of the eleventh embodiment- In the configuration of the eleventh embodiment as well, the heating operation of the first compressor (112) is continued by the second compressor (117) as in the seventh embodiment.
Thus, the outdoor heat exchanger (114) can be defrosted, so that a decrease in the heating capacity can be suppressed. Therefore, it is possible to prevent the room temperature from decreasing during the defrost operation.

-Modification of Embodiment 11- A modification of Embodiment 11 is shown in FIG. This air conditioner (170) is similar to the ninth embodiment and its modification (FIG.
And the second bypass passage (1) similar to that described in FIG.
52) and a flow rate adjusting mechanism (154), and a refrigerant heater (120a) is provided in the gas-liquid separator (120) in the same manner as described in the modified example of the tenth embodiment (FIG. 13B). ing. Second
The bypass passage (152) is connected to the intermediate expansion valve (1
19) or the intermediate expansion valve as shown by the phantom line.
(119) can be connected downstream.

In this way, similar to the above,
Since it is possible to increase the circulation amount of the refrigerant on the indoor side and prevent the liquid refrigerant from staying in the gas-liquid separator (120), it is possible to effectively prevent a decrease in the indoor temperature during the defrost operation.

In this example, the first bypass passage (151) described in the ninth embodiment and its modification is not provided, but the bypass passage (151) may be provided.
By doing so, the defrosting time of the outdoor heat exchanger (114) can be reduced. Also, the refrigerant heater (120a) is shown in FIG.
As described above, a refrigerant pipe connected to the gas-liquid separator (120) may be provided as shown by a virtual line.

[Brief description of the drawings]

FIG. 1 is a refrigerant circuit diagram of an air-conditioning apparatus according to Embodiment 1 of the present invention.

FIG. 2 is a Mollier diagram showing a state in which a heating operation and a defrost operation are simultaneously performed in the air-conditioning apparatus of FIG.

FIG. 3 is a refrigerant circuit diagram of an air-conditioning apparatus according to Embodiment 2 of the present invention.

FIG. 4 is a refrigerant circuit diagram of an air-conditioning apparatus according to Embodiment 3 of the present invention.

FIG. 5 is a refrigerant circuit diagram of an air conditioner according to Embodiment 4 of the present invention.

FIG. 6 is a refrigerant circuit diagram of an air conditioner according to Embodiment 5 of the present invention.

FIG. 7 is a refrigerant circuit diagram of an air conditioner according to Embodiment 6 of the present invention.

FIG. 8 is a conceptual diagram showing a state in which a heating operation and a defrost operation are simultaneously performed in an air conditioner according to Embodiment 7 of the present invention.

FIG. 9 is a refrigerant circuit diagram of the air conditioner of FIG.

FIG. 10 is a refrigerant circuit diagram of an air conditioner according to Embodiment 8 of the present invention.

FIG. 11 is a refrigerant circuit diagram of an air conditioner according to Embodiment 9 of the present invention.

FIG. 12 is a refrigerant circuit diagram showing a modification of FIG.

FIG. 13 shows a tenth embodiment of the present invention and a modification thereof, and FIG. 13 (a) shows a refrigerant heater provided in a refrigerant pipe,
FIG. 13B is a diagram illustrating a refrigerant heater provided in the gas-liquid separator, and FIG. 13C is a diagram illustrating a heat retaining mechanism provided in the gas-liquid separator.

FIG. 14 is a refrigerant circuit diagram of an air conditioner according to Embodiment 11 of the present invention.

FIG. 15 is a refrigerant circuit diagram showing a modified example of FIG.

FIG. 16 is a refrigerant circuit diagram of a conventional air conditioner that performs hot gas defrost.

FIG. 17 is a refrigerant circuit diagram of a conventional air conditioner that performs reverse cycle defrost.

18 is a Mollier chart showing a refrigerant circulation operation during a defrost operation in the air-conditioning apparatus of FIG.

FIG. 19 is a Mollier diagram showing a refrigerant circulation operation during a defrost operation in the air-conditioning apparatus of FIG.

[Explanation of symbols]

 (11a) First compressor (11b) Second compressor (13) Indoor heat exchanger (14) Indoor expansion valve (high-pressure holding means) (17) Outdoor heat exchanger (51) Bypass passage (53) Shut-off valve ( (71) Heat source unit (72) Intermediate unit (73) Utilization unit (81,82) Compressor (91) Indoor heat exchanger (93) Auxiliary compressor (112) First compressor (114) Outdoor Heat exchanger (115) Outdoor expansion valve (117) Second compressor (119) Intermediate expansion valve (120) Gas-liquid separator (120a) Refrigerant heater (refrigerant heating means) (120b) Refrigerant warmer (refrigerant warming means) (122) Indoor heat exchanger (123) Indoor expansion valve (141) Unload passage (142) Open / close valve (151) First bypass passage (152) Second bypass passage (153) Flow control mechanism (154) Flow control Mechanism (162) On-off valve (163) Communication passage

 ──────────────────────────────────────────────────の Continuing on the front page (72) Yoshikazu Sato, 1304 Kanaokacho, Sakai-shi, Osaka Daikin Industries Inside the Kanaoka Plant of Sakai Seisakusho Co., Ltd. (72) Takahiro Yamaguchi 1304, Kanaokacho, Sakai-shi, Osaka Daikin Industries, Ltd. 3L092 AA03 AA09 BA03 BA05 BA23 BA27 DA01 FA23 FA26 FA31

Claims (23)

[Claims] An air conditioner configured to perform a defrost operation by a gas refrigerant discharged from a compressor (11a, 11b), wherein a first compressor (11a) and a second compressor (11) are provided in a refrigerant circuit. 11b), the refrigerant discharged from the first compressor (11a) is supplied to the outdoor heat exchanger (17) during the defrost operation, and the refrigerant discharged from the second compressor (11b) is supplied to the indoor heat exchanger (13). An air conditioner configured to be supplied to an air conditioner. 2. The air conditioner according to claim 1, wherein the first compressor (11a) and the second compressor (11b) are connected in series to form a two-stage compression mechanism. 3. The air conditioner according to claim 1, wherein the first compressor (11a) and the second compressor (11b) are connected in parallel. 4. The air according to claim 1, wherein the capacity of the first compressor (11a) during the defrost operation is set to be larger than the capacity of the second compressor (11b). Harmony equipment. 5. An indoor heat exchanger (122) and an outdoor heat exchanger (11).
4), an intermediate expansion valve (119) and a gas-liquid separator (120) are provided in the liquid line (124L), and the gas outlet of the gas-liquid separator (120) It is connected to a gas line (124G) between the compressor (112) and the second compressor (117), and discharges refrigerant from the first compressor (112) via the outdoor heat exchanger (114) during defrost operation. Flows into the gas-liquid separator (120), and the refrigerant discharged from the second compressor (117) is supplied to the indoor heat exchanger.
(122) to the gas-liquid separator (120)
The air conditioner according to claim 1, wherein the gas refrigerant in the (120) is configured to be sucked into each of the compressors (112, 117). 6. A first compressor (112) for performing two-stage compression and a second compressor (112).
A gas-liquid separator (1G) is connected to the gas line (124G) between the compressor and the compressor (117).
20), and the liquid outlet of the gas-liquid separator (120) is connected to the liquid line (124L) between the outdoor heat exchanger (114) and the indoor heat exchanger (122). (124L) from the indoor expansion valve (123) to the intermediate expansion valve (1
19) is connected to the gas inlet to the gas-liquid separator (120), while between the indoor expansion valve (123) and the intermediate expansion valve (119),
The air conditioner according to claim 1, wherein a communication passage (163) having an on-off valve (162) is connected between the liquid outlet of the gas-liquid separator (120) and the outdoor expansion valve (115). 7. An unload passage (141) for bypassing a part of the refrigerant discharged from the second compressor (117) to the suction side during the defrost operation, and an on-off valve (1) is provided in the unload passage (141).
The air conditioner according to claim 5 or 6, further comprising (42). 8. A first bypass for bypassing a part of the refrigerant discharged from the first compressor (112) and flowing out of the outdoor heat exchanger (114) to a suction side of the first compressor (112) during a defrost operation. A flow path (151) is provided in said first bypass path (151), and a flow control mechanism (153) is provided in said first bypass path (151).
The air conditioner according to any one of the preceding claims. 9. A second bypass for bypassing a part of the refrigerant discharged from the second compressor (117) and flowing out of the indoor heat exchanger (122) to a suction side of the second compressor (122) during a defrost operation. A flow path (152), wherein the second bypass path (152) is provided with a flow control mechanism (154).
The air conditioner according to any one of the preceding claims. 10. A first compressor (112) during a defrost operation.
A first bypass passage (151) for bypassing a part of the refrigerant discharged from the outdoor heat exchanger (114) and flowing out of the outdoor heat exchanger (114) to a suction side of the first compressor (112); and a discharge from the second compressor (117). A part of the refrigerant that has flowed out of the indoor heat exchanger (122) is
(117) to the second bypass passage (15
7) The air conditioner according to claim 5, wherein the first bypass passage (151) and the second bypass passage (152) are provided with flow control mechanisms (153, 154), respectively. 11. A liquid line (124L) between an outdoor heat exchanger (114) and an outdoor expansion valve (115) is provided in a first bypass passage (151).
The air conditioner according to claim 8 or 10, wherein the air conditioner is connected to a gas line (124G) on the suction side of the first compressor (112). 12. A first bypass passage (151) includes a liquid line (124L) between an outdoor expansion valve (115) and a gas-liquid separator (120);
The air conditioner according to claim 8, wherein the air conditioner is connected to a gas line (124G) on a suction side of the first compressor (112). 13. A liquid line (124L) between the indoor heat exchanger (122) and the intermediate expansion valve (119).
The air conditioner according to claim 9 or 10, wherein the air conditioner is connected to a gas line (124G) on the suction side of the second compressor (117). 14. A second bypass passage (152) includes a liquid line (124L) between the intermediate expansion valve (119) and the gas-liquid separator (120);
The air conditioner according to claim 9 or 10, which is connected to a gas line (124G) on the suction side of the second compressor (117). 15. A gas-liquid separator during defrost operation (120)
The air conditioner according to any one of claims 5 to 14, wherein a refrigerant heating means (120a) for heating the refrigerant is provided in the refrigerant inflow pipe (124L) to the refrigerant. 16. The air conditioner according to claim 5, wherein a refrigerant heating means (120a) for heating the refrigerant is provided in a container body of the gas-liquid separator (120). 17. The air conditioner according to claim 5, wherein the container main body of the gas-liquid separator (120) is provided with a refrigerant heat retaining means (120b) for retaining the temperature of the refrigerant. 18. An air conditioner configured to perform a defrost operation with a gas refrigerant discharged from a compressor (11a, 11b), comprising: a bypass passage (51) connected in parallel with an indoor heat exchanger (13). ) And high-pressure holding means (14, 53) for closing the indoor heat exchanger (13) while holding it at a high pressure during defrost operation. 19. An air conditioner configured to be able to perform a defrost operation by a discharge gas of a compressor (11b), comprising a plurality of indoor heat exchangers (13a, 13b) connected in parallel, An air conditioner including high-pressure holding means (14a, 53) that sometimes closes a predetermined indoor heat exchanger (13a) while holding it at a high pressure. 20. A high-pressure holding means (14) during a defrost operation.
a, 53) by a predetermined indoor heat exchanger (13
a) is the indoor heat exchanger for the living room, and other indoor heat exchangers
The air conditioner according to claim 19, wherein (13b) is an indoor heat exchanger for a non-living room. 21. The high-pressure holding means (14, 53) (14a, 53) is constituted by an opening / closing mechanism provided so as to be able to close the inlet side and the outlet side of the indoor heat exchanger (13, 13a). Claim 1
21. The air conditioner according to any one of 8 to 20. 22. One of the opening and closing mechanisms is an electronic expansion valve (14, 14a).
22. The air conditioner according to claim 21, wherein the other is constituted by a closing valve (53). 23. Heat source units (71) and (111) provided with compressors (81, 82) and (112), and utilization units (73) provided with indoor heat exchangers (91) and (122). ) And (121), and the heat source units (71) and (111) and the utilization units (73) and (121) are provided with auxiliary compressors (93) and (117), The air conditioner according to any one of claims 1 to 22, wherein the air conditioner is connected via a removable intermediate unit (72), (116) for compressing.