JP2011163708A - Air conditioner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an air conditioner capable of resolving shortage of a refrigerant by efficiently delivering the refrigerant accumulated in an outdoor unit which is about to stop, to another outdoor unit connected thereto, and suppressing an amount of circulated refrigerant. <P>SOLUTION: This air conditioner includes an indoor unit 2 including an indoor heat exchanger and an indoor fan, the plurality of outdoor units 3 connected to the indoor unit in parallel, and configured by connecting a liquid tank, an expansion valve, a first outdoor heat exchanger, a four-way valve, an accumulator, and a capacity-controllable compressor, and a control section 4 for controlling operations of the indoor unit 2 and the outdoor units 3. The outdoor unit 3 includes a second outdoor heat exchanger 3j connected between the liquid tank 3i and the compressor 3d, and connected to the first outdoor heat exchanger 3b in parallel, a refrigerant return tube 3k connecting a secondary side of the second outdoor heat exchanger 3j and the liquid tank 3i and including a first two-way valve 31 on the way, and a discharge bypass tube 3m connecting a discharge side of the compressor 3d and an accumulator 3f, and including a second two-way valve 3n on the way. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an air conditioner capable of distributing an appropriate amount of refrigerant.

  In an air conditioner, for example, there may be a case where a plurality of outdoor units are connected in parallel in order to appropriately cope with operation requests from a plurality of indoor units. In this case, the number of outdoor units that can appropriately respond to the request based on the request of the indoor unit is operated.

  When the air conditioner is heated, the refrigerant may stay in the accumulator due to the defrosting operation or the like. Since the accumulated refrigerant gradually circulates in the refrigerating cycle such as another outdoor unit during the heating operation, the accumulation of the refrigerant in the accumulator is rarely a problem.

  However, if the outdoor unit that was in the heating operation is stopped based on a request from the indoor unit in a state where the refrigerant has accumulated in the accumulator, the refrigerant remains in the accumulator of the stopped outdoor unit. Such a state is similar to the state in which the total amount of refrigerant circulating in the refrigeration cycle is reduced. Therefore, adverse effects such as a decrease in heating performance due to insufficient refrigerant and heating of the refrigeration cycle may occur.

  Further, when the defrosting operation is further performed when the outdoor unit that has been stopped with the refrigerant remaining in the accumulator starts operation again, the refrigerant flows into the accumulator in addition to the remaining refrigerant. turn into. In such a state, the refrigerant in the accumulator may overflow and damage the compressor.

  In order to eliminate the above-described adverse effects, in the invention disclosed in Patent Document 1 shown below, when operating an outdoor unit in which refrigerant has accumulated in a stopped state, the outdoor unit lacking in refrigerant is stopped, The capacity of the outdoor unit in the entire harmony device can be made substantially equal to the capacity of the outdoor unit in which the refrigerant has accumulated before the operation. Moreover, the excess capacity driving | operation as the whole outdoor unit can be prevented.

JP 2000-220894 A

  However, in the invention disclosed in Patent Document 1 described above, excessive refrigerant is circulated when the number of indoor units operated and the capacity of operation are small. Therefore, the heating capacity becomes excessive and the comfort of the user of the air conditioner is impaired.

  Further, when only the outdoor unit in which the refrigerant has accumulated is operated, the compressor pressure increases due to the operation for discharging the accumulated refrigerant. As a result, the system stops before all of the accumulated refrigerant is discharged, and there are cases where sufficient refrigerant discharge operation cannot be performed.

  As a matter of course, the refrigerant cannot be discharged by reversing the four-way valve of the outdoor unit that has been stopped and performing the cooling cycle operation, but other outdoor units connected in parallel are not heated. Since the high-pressure refrigerant flows back to the outdoor unit that has been in operation and stopped, such control cannot be performed.

  The present invention has been made to solve the above-mentioned problems, and the object of the present invention is to send the refrigerant staying in the outdoor unit scheduled to be stopped to another outdoor unit that is efficiently connected. An object of the present invention is to provide an air conditioner that can solve the shortage of refrigerant and suppress the amount of refrigerant to be circulated.

  According to the embodiment of the present invention, an air conditioner includes an indoor heat exchanger, an indoor unit including an indoor fan, a plurality of indoor units connected in parallel, a liquid tank, an expansion valve, and a first outdoor heat. An outdoor unit that is formed by sequentially connecting an exchanger, a four-way valve, an accumulator, and a capacity-controllable compressor, and an indoor unit and a control unit that controls the operation of the outdoor unit. The outdoor unit is compressed with a liquid tank. And a second outdoor heat exchanger connected in parallel to the first outdoor heat exchanger and a secondary side of the second outdoor heat exchanger and the liquid tank, A refrigerant return pipe having a first two-way valve in the middle, a discharge side of the compressor and an accumulator are connected, and a discharge bypass pipe having a second two-way valve in the middle.

  According to the present invention, the refrigerant remaining in the outdoor unit scheduled to be stopped is efficiently sent to another connected outdoor unit, so that the shortage of refrigerant is solved and the amount of refrigerant to be circulated is suppressed. An air conditioner that can be provided can be provided.

1 is an overall view showing an overall circuit configuration of an air conditioner according to an embodiment of the present invention. It is a block diagram which shows the internal structure of the control part which concerns on embodiment of this invention. It is a flowchart which shows the operation | movement flow of the air conditioner which concerns on embodiment of this invention.

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

  FIG. 1 is an overall view showing an overall circuit configuration of an air conditioner 1 according to an embodiment of the present invention. The air conditioner 1 includes an indoor unit 2 and an outdoor unit 3. In the embodiment of the present invention, as shown in FIG. 1, there are four indoor units 2 (indoor units 2A to 2D) and two outdoor units 3 (first outdoor unit 3A and second outdoor unit 3B). )It is connected. In the following, the individual indoor units and outdoor units are collectively shown as the indoor unit 2 or the outdoor unit 3.

  In the embodiment of the present invention, the number of indoor units 2 may be single or plural, but a plurality of outdoor units 3 are connected. A plurality of outdoor units 3 are connected in parallel.

  The indoor unit 2 is installed indoors, and is connected to a plurality of outdoor units 3 via pipes P (liquid side pipes P1 and gas side pipes P2) through which refrigerant flows. The indoor units 2 shown in FIG. 1 have the same configuration. Therefore, the configuration of the indoor units 2A to 2D will be described together.

  The indoor unit 2 includes an indoor heat exchanger 2a, a flow rate adjusting valve 2b, and an indoor fan 2c. In the case of heating operation, the refrigerant flows in the direction of the arrow shown in FIG. A flow rate adjustment valve 2b is provided on the secondary side of the indoor heat exchanger 2a, that is, immediately after the refrigerant has left the indoor heat exchanger 2a. The flow rate adjusting valve 2b controls whether or not the refrigerant flows from the outdoor unit 3, and the refrigerant is supplied to the indoor unit 2 when the flow rate adjusting valve 2b is in an open state. The indoor heat exchanger 2a performs heat exchange between the refrigerant and the indoor air, and the air heated by the refrigerant is supplied into the room by the indoor fan 2c.

  The outdoor unit 3 is installed outdoors and is connected to the indoor unit 2 via a pipe P through which a refrigerant flows. As shown in FIG. 1, the air conditioner 1 according to the embodiment of the present invention includes a first outdoor unit 3A and a second outdoor unit 3B and two outdoor units connected in parallel. The devices provided in the same are all the same.

  The outdoor unit 3 includes an expansion valve 3a, a first outdoor heat exchanger 3b, a four-way valve 3c, and a compressor 3d that are sequentially connected. The expansion valve 3a is an electronic expansion valve whose open / close state is controlled by a control unit 4 described later. The compressor 3d is a variable capacity compressor. An outdoor fan 3e for promoting heat exchange in the first outdoor heat exchanger 3b is provided, and an accumulator 3f is provided between the four-way valve 3c and the compressor 3d.

In addition to the oil separator 3g, a check valve 3h is provided between the discharge side of the compressor 3d and the primary side of the four-way valve 3c. The check valve 3h is provided to prevent the refrigerant from flowing back from the four-way valve 3c to the compressor 3d.
A liquid tank 3i is provided on the primary side of the expansion valve 3a. The liquid tank 3i is used to adjust the amount of refrigerant that stores the refrigerant returned from the indoor unit 2 through the liquid side pipe P1 to the outdoor unit 3 and circulates in the refrigeration cycle.

  A second outdoor heat exchanger 3j is connected between the liquid tank 3i and the compressor 3d so as to be in parallel with the first outdoor heat exchanger 3b. If the first outdoor heat exchanger 3b is the main outdoor heat exchanger, the second outdoor heat exchanger 3j corresponds to a so-called auxiliary heat exchanger. This is used when the refrigerant discharge operation of the outdoor unit 3 described later is performed.

  The secondary side of the second outdoor heat exchanger 3j is connected to the liquid tank 3i, and the pipe connecting the two is the refrigerant that has accumulated in the accumulator 3f when the refrigerant discharge operation is performed. 3k is a refrigerant return pipe 3k passing through 3j. A first two-way valve 3l is provided in the middle of the refrigerant return pipe 3k, and its opening and closing is controlled by a command from the control unit 4.

  A discharge bypass pipe 3m is provided between the discharge side of the compressor 3d and the accumulator 3f. The discharge bypass pipe 3m serves to send the high-temperature refrigerant discharged from the compressor 3d to the accumulator 3f when the refrigerant discharge operation is performed. A second two-way valve 3n is provided in the middle of the discharge bypass pipe 3m, and its opening and closing is controlled by a command from the control unit 4.

  The opening / closing is controlled by a command from the control unit 4 in addition to the first two-way valve 3l and the second two-way valve 3n described above, the expansion valve 3a and the check valve 3h also control the opening / closing. Is done.

  On the primary side of the accumulator 3f, an evaporation temperature detection unit 3o that detects the evaporation temperature of the refrigerant sent from the first outdoor heat exchanger 3b is provided. In addition, a pipe temperature detection unit 3p that detects the temperature of the pipe connecting the first outdoor heat exchanger 3b and the accumulator 3f is also provided.

  On the other hand, on the discharge side of the compressor 3d, a condensation temperature detection unit 3q that detects the condensation temperature of the refrigerant and a discharge temperature detection unit 3r that detects the temperature of the discharged refrigerant are provided. In addition, about the evaporation temperature detection part 3o and the discharge temperature detection part 3r, a pressure sensor is used, for example, the pressure of the refrigerant | coolant which distribute | circulates the inside of piping is measured, and each temperature is calculated. This calculation may be performed by the determination unit 42 of the control unit 4 or may be performed by each unit such as the evaporation temperature detection unit 3o and the discharge temperature detection unit 3r.

  For the outdoor unit 3, one main outdoor unit is determined in advance, and the other outdoor units are operated based on instructions from the main outdoor unit, that is, they are subordinate outdoor units. . About this master-slave, you may carry out between the some outdoor units 3 how.

  The control unit 4 is provided in each outdoor unit 3. As described above, the outdoor unit 3 has a master-slave rating between the outdoor units 3, but the control unit 4 mounted on each outdoor unit 3 has the same configuration in any of the outdoor units 3. Alternatively, the main unit and the sub unit may be configured differently according to the personality rating of the outdoor unit 3. The control unit 4 here has the same configuration in any of the outdoor units 3, but is set with the first outdoor unit 3 </ b> A as the main and the second outdoor unit 3 </ b> B as the subordinate.

  In addition, although the control part 4 in the outdoor unit 3 shown in FIG. 1 omits the connection with each apparatus which comprises the outdoor unit 3, for convenience, each component apparatus of the outdoor unit 3, or indoor The machine 2 is also connected.

  FIG. 2 is a block diagram showing an internal configuration of the control unit 4. The control unit 4 includes a reception unit 41, a determination unit 42, a storage unit 43, and a transmission unit 44. In addition, the internal structure of the control part 4 shown in FIG. 2 has shown only the structure considered necessary when describing embodiment of this invention.

  The receiving unit 41 receives, for example, a control signal from the indoor unit 2 and information related to the refrigerant temperature. The determination unit 42 generates a signal for controlling the operation of each device in the outdoor unit 3 based on various information received by the reception unit, and sends the signal to each device via the transmission unit 44. The storage unit 43 stores in advance information necessary when the control unit 4 controls the operation of each device of the outdoor unit 3.

  Here, for example, the refrigeration cycle for heating will be briefly described by taking the first outdoor unit 3A as an example. In this case, the first two-way valve 3Al and the second two-way valve 3An are closed. As shown by the solid line arrow in FIG. 1, first, the refrigerant, which is a gas, is pressurized to a high temperature and a high pressure in the compressor 3Ad, and is sent to the indoor unit 2 via the four-way valve 3Ac and the gas side pipe P2. Supplied with. In the indoor unit 2, since the flow rate adjustment valve 2b is in an open state, the refrigerant flows through the indoor heat exchanger 2a. The medium supplied to the indoor heat exchanger 2a is condensed by exchanging heat with the indoor air, and heats the indoor air. This heated air is sent indoors through the indoor fan 2c.

  The refrigerant condensed in the indoor heat exchanger 2a becomes a liquid refrigerant, and passes through the liquid side pipe P1 as shown by the broken line arrow in FIG. 1, and the expansion valve in the first outdoor unit 3A. It is sent to the outdoor heat exchanger 3Ab via 3Aa. In the outdoor heat exchanger 3Ab, the refrigerant evaporates by heat exchange with outdoor air. The evaporated refrigerant flows out of the outdoor heat exchanger 3Ab, and is supplied again to the compressor 3Ad via the four-way valve 3Ac and the accumulator 3Af. Thereafter, the above cycle is repeated.

  FIG. 3 is a flowchart showing a flow of operation of the air conditioner according to the embodiment of the present invention. Hereinafter, according to this flowchart, the flow of operation of the air conditioner 1 will be described as appropriate together with the operation of each component of the control unit 4 described above.

  In the description of the embodiment of the present invention, it is assumed that the air conditioner 1 is in the heating operation. Further, the following determination by the control unit 4 is basically performed by the control unit 4A of the first outdoor unit 3A, which is the main outdoor unit representing the outdoor unit 3.

  The determination unit 42a of the control unit 4A makes a determination at any time as to whether or not there is a command to reduce the heating capacity from any of the indoor units 2 during the heating operation of the air conditioner 1 (ST1). If the user of the air conditioner 1 has no particular objection to the current heating operation capability, no command is issued to reduce the heating capability (NO in ST1). Operation control of the harmony machine 1 is continued (ST2).

  On the other hand, for example, when the user wants to reduce the heating capacity of the air conditioner 1 such as when the room gets hot, a command to reduce the heating capacity is issued from a controller (not shown) (YES in ST1). This “command to reduce the heating capacity” is, for example, a command to reduce the heating set temperature of the remote controller.

  The determination unit 42a that has received such a command via the reception unit 41a determines whether or not the amount of refrigerant circulating in the refrigeration cycle is an appropriate amount when the heating operation capability is reduced based on the command. (ST3). Although this determination criterion is not described in detail here, for example, the determination is made on the condition of the number of indoor units 2 in the heating operation, the set temperature, and the like. This determination criterion is stored in advance in the storage unit 43a, and the determination unit 42a determines based on the determination criterion stored in the storage unit 43a.

  As a result of this determination, even if the heating capacity is reduced and the heating operation is continued, the amount of refrigerant circulating in the refrigeration cycle is not particularly excessive, that is, the operation of any of the outdoor units 3 connected to a plurality of units is stopped. If it is determined that it is not necessary (NO in ST3), the heating capacity is reduced and the heating operation is continued (ST4). As described above, since the compressor 3Ad in the embodiment of the present invention is a variable capacity compressor 3d, the rotational speed of the compressor 3d in each outdoor unit 3 is set in accordance with the reduced heating capacity. Control. In continuing this heating operation, the operation capability of each outdoor unit 3 to which the determination unit 42a is connected is optimally controlled.

  When the determination unit 42a determines that the amount of refrigerant required when the heating capacity is reduced by a command to reduce the heating capacity is larger than the amount of refrigerant currently circulating in the refrigeration cycle Then, a determination is made to stop any one of the outdoor units 3 connected to ensure proper heating capacity (ST5). This is because supplying the refrigerant exceeding the required heating capacity to the indoor unit 2 is not suitable for the user's setting and is not preferable from the viewpoint of energy saving.

  The determination unit 42a determines which of the outdoor units 3 is to be stopped, and also determines which of the outdoor units 3 is to be stopped. In the following description, the case where the second outdoor unit 3B as the slave shown in FIG. 1 is stopped will be described as an example.

  The determination unit 42a further determines whether or not refrigerant has accumulated in the outdoor unit 3 (second outdoor unit 3B in this case) to be stopped (ST6). Since the refrigerant accumulates in the accumulator 3Bf, the determination unit 42a determines the retention state of the refrigerant in the accumulator 3Bf.

  Specifically, the refrigerant evaporation temperature Tj measured by the evaporation temperature detector 3Bo provided on the primary side of the accumulator 3Bf and the pipe temperature Ts measured by the pipe temperature detector 3Bp are expressed by the following equation (1). It is determined whether there is a relationship.

(Ts−Tj) ≦ Tb (1)

Here, “Tb” is a preset temperature (threshold value), and it is determined whether or not the refrigerant stays in the accumulator 3Bf based on this temperature. Note that the value of Tb is stored in advance in the storage unit 43a.

  When the determination unit 42a determines that the refrigerant is staying in the accumulator 3Bf (YES in ST6), the refrigerant is shifted to the refrigerant discharge operation before stopping the second outdoor unit 3B (ST7). Specifically, the operation of the second outdoor unit 3B is controlled as follows.

  The control unit 4B closes the expansion valve 3Ba shown in FIG. 1 and opens the first two-way valve 3Bl and the second two-way valve 3Bn. And the rotation speed of compressor 3Bd is made lower than compressor 3Ad of outdoor unit 3A. When the second two-way valve 3Bn is opened, the high-temperature and high-pressure gas discharged from the compressor 3Bd is sent to the accumulator 3Bf through the discharge bypass pipe 3Bm. The refrigerant staying in the accumulator 3Bf is heated by the high-temperature and high-pressure gas sent from the compressor 3Bd, and the evaporation thereof is promoted.

  Here, the high-temperature and high-pressure gas discharged from the compressor 3Bd is sent to the accumulator 3Bf through the discharge bypass pipe 3Bm. This is to end the process. That is, a heat source is required to quickly evaporate the liquid refrigerant in the accumulator 3Bf. However, since the amount of heat obtained from the outline of the accumulator 3bf is very small, a high-temperature refrigerant is introduced into the accumulator 3Bf from the compressor 3Bd via the discharge bypass pipe 3Bm as this heat source.

  The refrigerant in the accumulator 3Bf whose vaporization has been promoted is in a gas-liquid two-phase state, but is converted into a high-temperature and high-pressure gas in the compressor 3Bd and sent to the second outdoor heat exchanger 3Bj to be condensed. Here, since the pressure of the compressor 3Ad of the outdoor unit 3A is higher, the refrigerant discharged from the compressor 3Bd does not flow through the check valve 3Bh and does not flow to the gas side pipe P2, but the second outdoor heat exchanger. It flows to 3Bj. The refrigerant condensed in the second outdoor heat exchanger 3Bj passes through the refrigerant return pipe 3Bk and is sent to the liquid tank 3Bi because the first two-way valve 3Bl is opened.

  By performing the operation control in this way, the refrigerant that has accumulated in the accumulator 3Bf is discharged out of the second outdoor unit 3B that is scheduled to stop operation, and then to the first outdoor unit 3A that is currently in the heating operation. Sent.

  In FIG. 1, a large amount of liquid refrigerant stays in the accumulator 3Bf. This is clear even when compared with the accumulator 3Af of the first outdoor unit 3A during the heating operation. Further, the movement path of the gaseous refrigerant is indicated by an arrow indicated by a solid line, and the movement path of the liquid refrigerant is indicated by an arrow indicated by a broken line. The refrigerant discharged from the liquid tank 3Bi (second outdoor unit 3B) in the liquid state is sent to the liquid tank 3Ai of the first outdoor unit 3A as indicated by the dashed arrow.

  The determination unit 42 determines whether or not the refrigerant staying in the accumulator 3Bf has run out as appropriate (ST8). When it is determined that there is no remaining refrigerant (YES in ST8), the refrigerant discharge operation is terminated (ST9). . The condition for determining the presence or absence of convection refrigerant is that the condition shown in the following equation (2) continues for t minutes or more.

TD ≧ TG + α (2)

Here, “TD” is the temperature of the refrigerant discharged from the compressor 3Bd, and is detected by the discharge temperature detector 3Br. “TG” is the condensation temperature of the refrigerant discharged from the compressor 3Bd, and is detected by the condensation temperature detector 3Bq. If the discharge temperature TD of the refrigerant is equal to or higher than the condensation temperature TG + α (this “α” is a temperature range that can be arbitrarily set) and continues for more than t minutes, the liquid refrigerant stays in the accumulator 3Bf. It can be judged that it is not.

  The temperature range “α” and the duration “t” can be arbitrarily set and are stored in the storage unit 43b in advance. Moreover, although the condensation temperature detection part 3Bq is provided in the discharge side of compressor 3Bd, you may install in the middle of 2nd outdoor heat exchanger 3Bj.

  When it is determined that there is no refrigerant remaining in the second outdoor unit 3B to be stopped and the refrigerant discharge operation is completed (ST8, ST9), the corresponding outdoor unit (second outdoor unit 3B) is stopped. (ST10). Since the refrigerant does not stay in the second outdoor unit 3B, a situation in which the amount of refrigerant in the refrigeration cycle decreases even when the outdoor unit is stopped can be avoided. On the other hand, about 1st outdoor unit 3A, heating operation is continued as it is (ST11).

  As described above, the refrigerant remaining in the outdoor unit scheduled to be stopped is efficiently sent to other connected outdoor units, thereby eliminating the shortage of refrigerant and suppressing the amount of refrigerant to be circulated. An air conditioner that can be provided can be provided.

  That is, the refrigerant staying in the outdoor unit scheduled to be stopped is discharged from the outdoor unit to reduce the refrigerant in the accumulator in the outdoor unit scheduled to be stopped and sent to other outdoor units. While preventing the amount of refrigerant from decreasing, it is possible to avoid enclosing more refrigerant than necessary.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. Various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the above embodiments. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, you may combine the component covering different embodiment suitably.

DESCRIPTION OF SYMBOLS 1 ... Air conditioner, 2 ... Indoor unit, 3 ... Outdoor unit, 3a ... Expansion valve, 3b ... 1st outdoor heat exchanger, 3c ... Four-way valve, 3d ... Compressor, 3f ... Accumulator, 3i ... Liquid tank, 3j ... second outdoor heat exchanger, 3k ... refrigerant return pipe, 3l ... first two-way valve, 3m ... discharge bypass pipe, 3n ... second two-way valve, 3o ... evaporation temperature detection device, 3p ... piping Temperature detecting device, 3q ... Condensing temperature detecting device, 3r ... Refrigerant discharge temperature detecting device, 4 ... Control unit, P ... Piping

Claims (5)

An indoor heat exchanger, an indoor unit equipped with an indoor fan,
An outdoor unit connected in parallel with the indoor unit, and sequentially connecting a liquid tank, an expansion valve, a first outdoor heat exchanger, a four-way valve, an accumulator, and a compressor capable of controlling capacity;
A control unit for controlling the operation of the indoor unit and the outdoor unit,
The outdoor unit is
A second outdoor heat exchanger connected between the liquid tank and the compressor and connected in parallel to the first outdoor heat exchanger;
A refrigerant return pipe that connects the secondary side of the second outdoor heat exchanger and the liquid tank, and includes a first two-way valve in the middle thereof;
Connecting the discharge side of the compressor and the accumulator, a discharge bypass pipe having a second two-way valve in the middle thereof;
An air conditioner comprising: A pipe temperature detection device for measuring the temperature of the pipe installed in the pipe connecting the first outdoor heat exchanger and the accumulator;
An evaporating temperature detecting device for measuring a temperature of the refrigerant evaporated by the first outdoor heat exchanger flowing from the first outdoor heat exchanger to the accumulator;
A refrigerant discharge temperature detection device for measuring the temperature of the refrigerant discharged from the compressor provided on the discharge side of the compressor;
A condensing temperature detector for measuring the condensing temperature of the refrigerant discharged from the compressor provided on the discharge side of the compressor;
The air conditioner according to claim 1, comprising:   When the refrigerant is accumulated in the accumulator of the outdoor unit scheduled to be shut down when the operation of the outdoor unit is stopped, the control unit is disposed inside the accumulator outside the outdoor unit scheduled to be shut down. The air conditioner according to claim 1 or 2, wherein an operation for discharging the refrigerant is performed.   When the temperature difference between the pipe temperature detected by the pipe temperature detection device and the refrigerant evaporation temperature detected by the evaporation temperature detection device is equal to or less than a predetermined threshold, the control unit The air conditioner according to any one of claims 1 to 3, wherein a determination is made to shift to a discharge operation.   When the temperature difference between the refrigerant discharge temperature detected by the refrigerant and the outlet temperature detection device and the refrigerant condensation temperature detected by the condensation temperature detection device is equal to or greater than a predetermined threshold, The air conditioner according to any one of claims 1 to 4, wherein a determination is made to stop the refrigerant discharge operation.

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