JP2015075272A - Air conditioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an air conditioner capable of recovering a refrigerant in an outdoor unit without going through an indoor unit during a refrigerant recovery operation, and capable of reducing a refrigerant leakage amount even in the air conditioner in which the amount of sealed refrigerant is large.SOLUTION: When performing a refrigerant recovery operation for recovering a refrigerant in an outdoor unit 2, an outdoor expansion valve 25, a liquid refrigerant shut-off valve 51 and an indoor expansion valve 81 are closed, the refrigerant staying in an indoor unit 3 and a gas refrigerant pipeline 102 is recovered in the outdoor unit 2, and a gas refrigerant shut-off valve 52 is closed. After that, the refrigerant staying in a liquid refrigerant pipeline 101 is recovered from a bypass circuit comprising a first bypass pipe 27a, a cooling side pipeline 27d of a supercooling heat exchanger 27 and a second bypass pipe 27b, and the liquid refrigerant shut-off valve 51 is closed. Thus, the refrigerant staying in the liquid refrigerant pipeline 101 can be recovered in the outdoor unit 2 without going through the indoor unit 3, and a refrigerant leakage amount can be reduced.

Description

  The present invention relates to an air conditioner in which an outdoor unit and an indoor unit are connected by a plurality of refrigerant pipes. More specifically, the present invention relates to a refrigerant recovery operation for recovering a refrigerant sealed in the air conditioner to an outdoor unit. is there.

  Currently, HFC refrigerants that do not destroy the ozone layer are used for refrigerants such as air conditioners. However, this HFC-based refrigerant has a very high global warming potential and is subject to emission regulations to prevent global warming. Therefore, various methods have been proposed for reducing the amount of refrigerant leakage in an air conditioner. For example, when refrigerant leaks on the indoor unit side, it is proposed to collect the refrigerant on the outdoor unit side. .

  In an air conditioner described in Patent Document 1, an outdoor unit having a compressor and an outdoor heat exchanger and an indoor unit having an indoor heat exchanger are sequentially connected by a liquid refrigerant pipe and a gas refrigerant pipe, and the liquid refrigerant pipe In the middle of the gas refrigerant pipe, a liquid refrigerant pipe on-off valve and a gas refrigerant pipe on-off valve are provided. Furthermore, the air conditioner is provided with a refrigerant leakage detection device in a room where the indoor unit is installed, and when the refrigerant leakage detection device detects leakage of a refrigerant exceeding a predetermined level, the indoor unit, a gas refrigerant pipe, a liquid refrigerant pipe, A refrigerant recovery operation is performed to recover the refrigerant remaining in the outdoor unit to the outdoor unit. In the refrigerant recovery operation, the liquid refrigerant piping on-off valve is closed and the compressor is operated for a predetermined time or until the suction side pressure of the compressor drops to a predetermined value. Close the valve. The refrigerant collected in the outdoor unit is accumulated in the outdoor heat exchanger because the liquid refrigerant piping on-off valve is closed. At this time, the refrigerant staying in the liquid refrigerant pipe flows from the indoor unit to the gas refrigerant pipe and is collected in the outdoor unit.

Japanese Patent Laid-Open No. 5-118720

  In the air conditioner described in Patent Document 1, the refrigerant stagnating in the liquid refrigerant pipe is always recovered to the outdoor unit through the indoor unit during the refrigerant recovery operation, and thus refrigerant leakage occurs in the indoor unit. In this case, when the refrigerant staying in the liquid refrigerant pipe flows through the indoor unit in the refrigerant recovery operation, the refrigerant may leak further into the room.

  In general, a large-scale air conditioner installed in a building or the like has a larger amount of enclosed refrigerant than a domestic air conditioner. This is because a large-scale air conditioner installed in a building or the like has a plurality of indoor units arranged over the entire building, and therefore has a refrigerant pipe that connects the outdoor unit and the indoor unit compared to a home air conditioner. This is because the length of the refrigerant pipe increases, and the amount of refrigerant necessary for the air conditioner increases. Therefore, when a refrigerant leak occurs in an indoor unit in a large air conditioner, there is a risk that the amount of refrigerant leak may be larger than that in a home air conditioner, and measures to reduce this refrigerant leak amount are required. .

  An object of the present invention is to solve the above problems and provide an air conditioner that can reduce the amount of refrigerant leakage during the refrigerant recovery operation.

  In order to solve the above-described problems, an air conditioner of the present invention includes an outdoor unit having a compressor, an outdoor heat exchanger, an outdoor open / close valve, and an accumulator, an indoor heat exchanger, and an indoor open / close valve. The indoor unit is connected with a liquid refrigerant pipe and a gas refrigerant pipe. The outdoor unit includes a liquid refrigerant shut-off mechanism capable of shutting off a refrigerant flow in the liquid refrigerant pipe, a gas refrigerant shut-off mechanism capable of shutting off a refrigerant flow in the gas refrigerant pipe, and an outdoor on-off valve. A bypass circuit having a refrigerant recovery on-off valve that bypasses between the liquid refrigerant blocking mechanism and the gas refrigerant blocking mechanism and the accumulator, and when performing a refrigerant recovery operation for recovering the refrigerant in the outdoor unit, Close the liquid refrigerant shut-off mechanism, open the gas refrigerant shut-off mechanism, close the gas refrigerant shut-off mechanism and / or open the liquid refrigerant shut-off mechanism. Thus, a liquid refrigerant recovery operation for recovering the refrigerant staying in the liquid refrigerant pipe is performed.

  According to the air conditioner of the present invention configured as described above, during the refrigerant recovery operation, the refrigerant staying in the indoor unit and the gas refrigerant pipe is collected in the outdoor unit, and the refrigerant in the liquid refrigerant pipe is passed through the bypass circuit. Is collected in the outdoor unit, the refrigerant in the liquid refrigerant pipe can be collected without going through the indoor unit, and the amount of refrigerant leakage can be reduced.

It is a refrigerant circuit figure of the air conditioner which is Example 1 of this invention, and is a refrigerant circuit figure which shows the flow of the refrigerant | coolant in the case of performing cooling operation and heating operation. It is a refrigerant circuit diagram which shows the opening-and-closing state of the valve at the time of the gas refrigerant | coolant recovery driving | operation which is one of the refrigerant | coolant recovery driving | operations, and the flow of a refrigerant | coolant in Example 1 of this invention. It is a refrigerant circuit diagram which shows the open / close state of the valve at the time of the liquid refrigerant recovery operation which is one of the refrigerant recovery operations in Example 1 of this invention, and the flow of a refrigerant | coolant. It is a refrigerant circuit diagram which shows the opening-and-closing state of the valve at the time of heat exchanger discharge operation | movement, and the flow of a refrigerant | coolant in Example 1 of this invention. It is a refrigerant circuit diagram which shows the opening-and-closing state of the valve at the time of the excess refrigerant | coolant discharge operation in Example 1 of this invention, and the flow of a refrigerant | coolant. It is a flowchart which shows the flow of a process of refrigerant | coolant collection | recovery driving | operation in Example 1 of this invention. It is a flowchart which shows the flow of a process of the heat exchanger refrigerant | coolant discharge driving | operation in Example 1 of this invention. It is a flowchart which shows the flow of a process of the excess refrigerant | coolant discharge driving | operation in Example 1 of this invention. It is a refrigerant circuit figure of the air conditioner which is Example 2 of this invention, and is a refrigerant circuit figure which shows the flow of the refrigerant | coolant in the case of performing cooling operation and heating operation.

  Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. In the following description, an air conditioner in which one outdoor unit and one indoor unit are connected by a refrigerant pipe will be described as an example. The present invention is not limited to the following embodiments, and can be variously modified without departing from the gist of the present invention.

  FIG. 1 shows an air conditioner 1 according to this embodiment. The air conditioner 1 includes a compressor 21, a four-way valve 22 that is a flow path switching unit, an outdoor heat exchanger 23, an outdoor fan 24, an outdoor expansion valve 25 that is an outdoor on-off valve, an accumulator 26, and a supercooling heat exchanger 27. An outdoor unit 2 having a supercooling expansion valve 28 serving as a refrigerant recovery on-off valve, a liquid refrigerant shut-off valve 51 serving as a liquid refrigerant shut-off mechanism, a gas refrigerant shut-off valve 52 serving as a gas refrigerant shut-off mechanism, and an indoor side open / close valve. The indoor unit 3 includes an indoor expansion valve 81, an indoor heat exchanger 82, and an indoor fan 83, a liquid refrigerant pipe 101 and a gas refrigerant pipe 102 that connect the outdoor unit 2 and the indoor unit 3, and the outdoor fan 24 and the indoor fan 83. Each component except for is connected to each other through a refrigerant pipe to form a refrigerant circuit.

  First, each configuration of the outdoor unit 2 will be described. The compressor 21 is a variable capacity compressor that can vary its operating capacity by being driven by a motor (not shown) whose rotation speed is controlled by an inverter. The discharge side of the compressor 21 is connected to the four-way valve 22 by refrigerant piping, and the suction side of the compressor 21 is connected to the accumulator 26 by refrigerant piping.

  The four-way valve 22 is a valve for switching the direction in which the refrigerant flows, and includes four ports a, b, c, and d. Port a is connected to the discharge side of the compressor 21, port b is connected to the outdoor heat exchanger 23, port c is connected to the accumulator 26, and port d is connected to the indoor unit 3 via the gas refrigerant shut-off valve 52 through refrigerant piping. The

  The outdoor heat exchanger 23 performs heat exchange between the refrigerant and the outdoor air, and one refrigerant inlet / outlet is connected to the port b of the four-way valve 22, and the other refrigerant inlet / outlet is connected to the indoor unit 3 via the outdoor expansion valve 25. Each is connected by refrigerant piping. The outdoor expansion valve 25 adjusts the refrigerant flow rate in the outdoor heat exchanger 23, is driven by a pulse motor (not shown), and the opening degree of the valve is adjusted by the number of pulses applied to the pulse motor. In the outdoor expansion valve 25, one port is connected to the outdoor heat exchanger 23, and the other port is connected to the cooled side pipe 27c of the supercooling heat exchanger 27 through a refrigerant pipe. In this embodiment, the outdoor open / close valve is an outdoor expansion valve. However, the present invention is not limited to this. For example, an electromagnetic open / close valve and a pressure reducing means (capillary tube or electronic expansion valve) are combined in parallel. It may be configured to have a function of adjusting the refrigerant flow rate.

  The outdoor fan 24 is disposed in the vicinity of the outdoor heat exchanger 23 and is rotated by a fan motor (not shown), thereby taking outdoor air into the outdoor unit 2 and exchanging heat with refrigerant in the outdoor heat exchanger 23. Release outside.

  The accumulator 26 is a container capable of accumulating surplus refrigerant generated in response to a change in the operating load of the indoor unit 3. The refrigerant inflow side is connected to the port c of the four-way valve 22 by a refrigerant pipe, and the refrigerant outflow side is a compressor. 21 is connected to the suction side by a refrigerant pipe. The accumulator 26 is provided with an electric heater (not shown) (for example, a belt heater) that heats the accumulator 26.

  The subcooling heat exchanger 27 is a double pipe heat exchanger in which an outer cooled side pipe (outer pipe) 27c and an inner cooled side pipe (inner pipe) 27d are coaxial pipes. Heat exchange is performed between the refrigerant in the pipe 27c and the refrigerant in the cooling side pipe 27d. One end of the cooled side pipe 27c is connected to the outdoor expansion valve 25 and the other end is connected to the liquid refrigerant shut-off valve 51 by a refrigerant pipe. The cooling side pipe 27d has one end connected to the outdoor expansion valve 25 and the subcooling heat exchanger 27. The other end is connected to the junction 62 between the port c of the four-way valve 22 and the accumulator 26 via the second bypass pipe 27b. The first bypass pipe 27a may be configured to branch from a refrigerant pipe between the supercooling heat exchanger 27 and the liquid refrigerant cutoff valve 51. A supercooling expansion valve 28 is provided in the first bypass pipe 27a that connects the branch portion 61 and the cooling side pipe 27d. The supercooling expansion valve 28 adjusts the refrigerant flow rate to the cooling side pipe 27d of the supercooling heat exchanger 27, is driven by a pulse motor (not shown), and the opening degree of the valve is adjusted by the number of pulses applied to the pulse motor. Is done. In this embodiment, the refrigerant recovery on-off valve is a supercooled expansion valve, but the invention is not limited to this. For example, an electromagnetic on-off valve and a pressure reducing means (capillary tube or electronic expansion valve) are arranged in parallel. It may be configured to have a function of adjusting the refrigerant flow rate in combination.

  The liquid refrigerant shut-off valve 51 shuts off the refrigerant flow in the liquid refrigerant pipe 101 that connects the outdoor unit 2 and the indoor unit 3, one side being the cooled side pipe 27 c of the supercooling heat exchanger 27 and the other side. Are connected to one end of the liquid refrigerant pipe 101 by a refrigerant pipe.

  The gas refrigerant shut-off valve 52 shuts off the refrigerant flow in the gas refrigerant pipe 102 connecting the outdoor unit 2 and the indoor unit 3, one end of the gas refrigerant pipe 102 and the other port of the four-way valve 22. d and refrigerant pipes respectively.

  The outdoor unit 2 includes a discharge pressure sensor 31 that is a discharge pressure detection unit and a discharge temperature sensor 41 that is a discharge temperature detection unit on the discharge side of the compressor 21, and a suction pressure detection unit on the suction side of the compressor 21. A suction pressure sensor 32, and a suction temperature sensor 42 serving as suction temperature detection means. Although not shown, in addition, the temperature of the refrigerant flowing into or out of the outdoor heat exchanger 23, the temperature of the refrigerant flowing into or out of the cooled side pipe 27c of the supercooling heat exchanger 27, the supercooling heat exchanger Various temperature sensors for detecting the temperature of the refrigerant flowing out from the cooling side pipe 27d and the outside air temperature are provided.

  The outdoor unit 2 is provided with an outdoor control device 29. The outdoor control device 29 includes a communication unit and a control unit (not shown). The communication unit exchanges operation information with the indoor control device 84, which will be described later, via a communication line (not shown). The control unit uses the operation information such as the result detected by each sensor and the required capacity sent from the indoor unit 3 to control the drive of the compressor 21, the switching control of the four-way valve 22, the drive control of the outdoor fan 24, Opening control of outdoor expansion valve 25 and supercooling expansion valve 28, opening / closing control of liquid refrigerant shutoff valve 51 and gas refrigerant shutoff valve 52, measurement of operation time, calculation of discharge superheat degree and suction superheat degree, attached to accumulator 26 Energization / non-energization of an electric heater (not shown) is performed.

  Next, each configuration of the indoor unit 3 will be described. The indoor heat exchanger 82 performs heat exchange between the refrigerant and the room air, and one refrigerant inlet / outlet is connected to the other end of the gas refrigerant pipe 102 and the other refrigerant inlet / outlet is connected to the indoor expansion valve 81 via the refrigerant pipe. Is done. The indoor expansion valve 81 adjusts the refrigerant flow rate in the indoor heat exchanger 82, is driven by a pulse motor (not shown), and the opening degree of the valve is adjusted by the number of pulses applied to the pulse motor. The indoor expansion valve 81 has one port connected to the indoor heat exchanger 82 and the other port connected to the other end of the liquid refrigerant pipe 101 through a refrigerant pipe. In this embodiment, the indoor open / close valve is an indoor expansion valve. However, the present invention is not limited to this. For example, an electromagnetic open / close valve and a pressure reducing means (capillary tube or electronic expansion valve) are combined in parallel. It may be configured to have a function of adjusting the refrigerant flow rate.

  The indoor fan 83 is disposed in the vicinity of the indoor heat exchanger 82 and is rotated by a fan motor (not shown) so that the indoor air is taken into the indoor unit 3 and heat is exchanged with the refrigerant by the indoor heat exchanger 82. Release outside the indoor unit 3. The indoor unit 3 is also provided with various temperature sensors for detecting the temperature of the refrigerant flowing into or out of the indoor heat exchanger 82 and the indoor temperature.

  The indoor unit 3 includes an indoor control device 84. The indoor control device 84 includes a communication unit and a control unit (not shown). The communication unit exchanges operation information with the outdoor control device 29 at any time via a communication line (not shown). The control unit performs the opening control of the indoor expansion valve 81, the drive control of the indoor fan 83, and the like according to the results detected by the sensors and the operation information sent from the outdoor control device 29.

  As described above, the air conditioner 1 is configured by connecting the outdoor unit 2 and the indoor unit 3 with the liquid refrigerant pipe 101 and the gas refrigerant pipe 102. The air conditioner 1 according to the present embodiment switches the four-way valve 22 to perform the cooling operation or the heating operation, and controls each device according to the operation load of the indoor unit 3.

  Next, the operation | movement operation | movement of the air conditioner 1 of a present Example is demonstrated. The air conditioner 1 according to the present embodiment can perform a cooling operation, a heating operation, and a refrigerant recovery operation according to the present invention.

  First, the cooling operation will be described with reference to FIG.

  During the cooling operation, the four-way valve 22 is switched to communicate with the ports a and b and the ports c and d to communicate with each other, and the four-way valve 22 is indicated by a solid line. The refrigerant circulates in the direction in which it is located. The outdoor heat exchanger 23 functions as a condenser, the indoor heat exchanger 82 functions as an evaporator, and the liquid refrigerant shut-off valve 51 and the gas refrigerant shut-off valve 52 are always open. The outdoor expansion valve 25 is fully opened. In the supercooling expansion valve 28, the refrigerant flowing out of the supercooling expansion valve 28 passes through the first bypass pipe 27 a and flows into the cooling side pipe 27 d of the supercooling heat exchanger 27. After heat exchange with the refrigerant flowing through the cooling side pipe 27c, the opening degree is adjusted according to the degree of superheat on the refrigerant outlet side of the cooling side pipe 27d of the supercooling heat exchanger 27. The opening of the indoor expansion valve 81 is adjusted according to the degree of superheat on the refrigerant outlet side of the indoor heat exchanger 82. The rotational speed of the outdoor fan 24 is controlled so that the discharge pressure detected by the discharge pressure sensor 31 or the condensation temperature in the outdoor heat exchanger 23 converted from the value detected by the discharge pressure sensor 31 is constant. The indoor fan 83 is driven at a rotational speed corresponding to the air volume set by the user.

  Next, the heating operation will be described with reference to FIG.

  During the heating operation, the four-way valve 22 is switched to communicate with the ports a and d of the four-way valve 22 and the ports b and c to communicate with each other, and the four-way valve 22 is indicated by a dotted line. The refrigerant circulates in the direction in which it is located. The indoor heat exchanger 82 functions as a condenser, and the outdoor heat exchanger 23 functions as an evaporator. The liquid refrigerant cutoff valve 51 and the gas refrigerant cutoff valve 52 are always open. The opening of the indoor expansion valve 81 is adjusted according to the degree of supercooling on the refrigerant outlet side of the indoor heat exchanger 82. In the supercooling expansion valve 28, the refrigerant flowing out of the supercooling expansion valve 28 passes through the first bypass pipe 27 a and flows into the cooling side pipe 27 d of the supercooling heat exchanger 27. After heat exchange with the refrigerant flowing through the cooling side pipe 27c, the opening degree is adjusted according to the degree of superheat on the refrigerant outlet side of the cooling side pipe 27d of the supercooling heat exchanger 27. The opening degree of the outdoor expansion valve 25 is adjusted according to the degree of superheat on the refrigerant outlet side of the outdoor heat exchanger 23. The outdoor fan 24 controls the rotation speed so that the suction pressure detected by the suction pressure sensor 32 or the evaporation temperature in the outdoor heat exchanger 23 converted from the value detected by the suction pressure sensor 32 becomes constant. The indoor fan 83 is driven at a rotational speed corresponding to the air volume set by the user.

  Next, the refrigerant recovery operation according to the present invention will be described with reference to FIGS. The refrigerant recovery operation of the present invention includes a gas refrigerant recovery operation that recovers refrigerant that stays in the indoor unit 3 and the gas refrigerant pipe 102, and a liquid refrigerant recovery operation that recovers refrigerant that stays in the liquid refrigerant pipe 101. When a refrigerant leak is detected in step 1, the gas refrigerant recovery operation is performed first, followed by the liquid refrigerant recovery operation. FIG. 2 shows the open / closed state of each valve during the gas refrigerant recovery operation. FIG. 3 shows the open / closed state of each valve during the liquid refrigerant recovery operation. The open / closed state of each valve is shown in black when it is closed, and white when it is open. Moreover, the flow of the refrigerant at the time of each refrigerant recovery operation is illustrated by a one-dot chain line arrow.

  The purpose of the refrigerant recovery operation in the present invention is to recover the refrigerant staying in the liquid refrigerant pipe 101 without going through the indoor unit 3. Therefore, it is necessary to provide a bypass circuit for flowing the refrigerant from the liquid refrigerant pipe 101 side to the compressor 21 suction side. In the present embodiment, this bypass circuit includes a first bypass pipe 27a, a second bypass pipe 27b, and a cooling side pipe 27d of the supercooling heat exchanger 27. In addition, when a large amount of refrigerant stays in the indoor unit 3, the liquid refrigerant pipe 101, and the gas refrigerant pipe 102, the outdoor heat exchanger 23 alone may not be able to recover the refrigerant. The amount of refrigerant that stays in the indoor unit 3, the liquid refrigerant pipe 101, and the gas refrigerant pipe 102 increases, and the room from the indoor side (the indoor heat exchanger 82, the liquid refrigerant pipe 101, and part of the gas refrigerant pipe 102) in the refrigerant circuit. There was a risk that the amount of refrigerant leaking into the tank would increase. Therefore, in this embodiment, the accumulator 26 is used as a refrigerant collection place other than the outdoor heat exchanger 23 in the outdoor unit 2.

  In the refrigerant recovery operation, the outdoor control device 29 receives an output signal from a refrigerant detection sensor installed in the room, or a refrigerant recovery operation start signal transmitted by a serviceman operating the indoor control device 84 or a remote controller (not shown). Or the outdoor control device 29 is directly operated. When the refrigerant recovery operation is executed, the outdoor control device 29 confirms whether or not the four-way valve 22 is in the state indicated by the solid line shown in FIG. 2, that is, the state when the cooling operation is performed. . At this time, if the four-way valve 22 is in a state indicated by a dotted line, the outdoor control device 29 switches the four-way valve 22 to a state indicated by a solid line.

  First, in the gas refrigerant recovery operation, the opening / closing operation of each valve and the flow of the refrigerant will be described.

  When performing the gas refrigerant recovery operation, the outdoor control device 29 instructs the indoor control device 84 to close the indoor expansion valve 81, and sets the outdoor expansion valve 25, the supercooling expansion valve 28, and the liquid refrigerant cutoff valve 51. close up. Thereby, a refrigerant circuit will be in the state shown in FIG. The outdoor control device 29 drives the compressor 21 and the outdoor fan 24 in order to condense the refrigerant collected in the outdoor unit 2 and collect it in the outdoor heat exchanger 23, and stays in the indoor heat exchanger 82. In order to evaporate the refrigerant and collect it in the outdoor unit 2, the indoor fan 83 is driven to start the gas refrigerant recovery operation.

  When the compressor 21 is started, the refrigerant staying on the indoor heat exchanger 82 side from the indoor expansion valve 81 in the indoor unit 3 and the refrigerant staying on the gas refrigerant pipe 102 flow as indicated by a one-dot chain line arrow shown in FIG. Flow into the outdoor unit 2. The refrigerant that has flowed into the outdoor unit 2 flows into the accumulator 26 through the four-way valve 22 and the junction portion 62. Of the refrigerant that has flowed into the accumulator 26, the liquid refrigerant stays in the accumulator 26, the gas refrigerant is sucked into the compressor 21, and flows into the outdoor heat exchanger 23 from the compressor 21 through the four-way valve 22. The refrigerant that has flowed into the outdoor heat exchanger 23 flows toward the outdoor expansion valve 25, but the outdoor expansion valve 25 is closed, so that the refrigerant accumulates in the outdoor heat exchanger 23.

  When the gas refrigerant recovery operation is performed, the indoor expansion valve 81 is closed, so that the refrigerant staying in the liquid refrigerant pipe 101 does not flow into the indoor unit 3. Further, since the outdoor expansion valve 25, the supercooling expansion valve 28, and the liquid refrigerant shut-off valve 51 are closed, the refrigerant stays in the refrigerant pipe between the outdoor expansion valve 25 and the liquid refrigerant shut-off valve 51 in the outdoor unit 2. The refrigerant and the refrigerant staying in the first bypass pipe 27 a between the junction 61 and the supercooling expansion valve 28 are confined between the outdoor expansion valve 25, the supercooling expansion valve 28, and the liquid refrigerant shut-off valve 51. Therefore, the refrigerant staying at this place does not flow from the supercooling heat exchanger 27 to the accumulator 26 through the junction 62.

  When performing the gas refrigerant recovery operation, the outdoor control device 29 periodically takes in the suction pressure detected by the suction pressure sensor 32, and the taken-in suction pressure is a first predetermined threshold pressure (for example, 0.01 MPa). If it becomes below, it will be judged that collection | recovery of the refrigerant | coolant stagnated in the indoor unit 3 and gas refrigerant | coolant piping 102 was completed. Further, in the gas refrigerant recovery operation, when the pressure in the indoor unit 3 and the gas refrigerant pipe 102 becomes equal to or lower than the atmospheric pressure, air flows into the indoor unit 3 and the gas refrigerant pipe 102 from the refrigerant leak part, and the size of the refrigerant leak part. In some cases, the compressor 21 continues to suck air, and the suction pressure may not be lower than the first predetermined threshold pressure. Therefore, the outdoor control device 29 measures the operation time after starting the gas refrigerant recovery operation. When the operation time of the gas refrigerant recovery operation passes a first predetermined time (for example, 180 seconds), it is determined that the recovery of the refrigerant staying in the indoor unit 3 and the gas refrigerant pipe 102 is completed. The operation time is confirmed in advance by a test, and is set to a time during which the refrigerant staying in the indoor unit 3 and the gas refrigerant pipe 102 can be recovered according to the installation situation. Then, the outdoor control device 29 closes the gas refrigerant shutoff valve 52 and ends the gas refrigerant recovery operation. Since the gas refrigerant recovery operation is switched to the liquid refrigerant recovery operation at the same time as the end of the gas refrigerant recovery operation, the compressor 21, the outdoor fan 24, and the indoor fan 83 are kept driven.

  Next, the open / close state of each valve and the flow of the refrigerant in the liquid refrigerant recovery operation will be described.

  When performing the liquid refrigerant recovery operation, the outdoor control device 29 keeps the outdoor expansion valve 25 and the indoor expansion valve 81 closed, and opens the supercooling expansion valve 28 and the liquid refrigerant cutoff valve 51. As a result, the refrigerant circuit enters the state shown in FIG. 3, and the liquid refrigerant recovery operation is started. The compressor 21, the outdoor fan 24, and the indoor fan 83 are continuously driven from the gas refrigerant recovery operation.

  When the liquid refrigerant recovery operation is started, the refrigerant staying in the liquid refrigerant pipe 101 flows as indicated by a one-dot chain line arrow shown in FIG. 3 and flows into the outdoor unit 2. The refrigerant flowing into the outdoor unit 2 passes through the cooled side pipe 27c of the supercooling heat exchanger 27, the first bypass pipe 27a, the cooling side pipe 27d of the supercooling heat exchanger 27, the second bypass pipe 27b, and the junction 62. Through the accumulator 26. Of the refrigerant that has flowed into the accumulator 26, the liquid refrigerant stays in the accumulator 26, the gas refrigerant is sucked into the compressor 21, and flows into the outdoor heat exchanger 23 from the compressor 21 through the four-way valve 22. The refrigerant that has flowed into the outdoor heat exchanger 23 flows toward the outdoor expansion valve 25, but the outdoor expansion valve 25 is closed, so that the refrigerant accumulates in the outdoor heat exchanger 23.

  When the liquid refrigerant recovery operation is performed, the indoor expansion valve 81 is closed and the refrigerant is recovered from the liquid refrigerant pipe 101 side of the outdoor unit 2 to the outdoor unit 2, so that the refrigerant staying in the liquid refrigerant pipe 101 is stored indoors. It does not flow into the machine 3. Further, since the gas refrigerant shutoff valve 52 is closed, the refrigerant staying in the liquid refrigerant pipe 101 flows from the first bypass pipe 27a, the cooling side pipe 27d of the supercooling heat exchanger 27, and the second bypass pipe 27b to the junction 62. And it does not flow into the indoor unit 3 and the gas refrigerant pipe 102 via the four-way valve 22.

  During the liquid refrigerant recovery operation, the outdoor control device 29 periodically takes in the suction pressure detected by the suction pressure sensor 32, and the taken-in suction pressure is a second predetermined threshold pressure (for example, 0. 0). 05 MPa) or less, it is determined that the recovery of the refrigerant staying in the liquid refrigerant pipe 101 has been completed. In addition, since the refrigerant leakage may occur on the liquid refrigerant pipe 101 side with respect to the indoor expansion valve 81, the outdoor control device 29 operates similarly to the gas refrigerant recovery operation after the liquid refrigerant recovery operation is started. Even if the taken-in suction pressure does not become the second predetermined threshold pressure or less, if the operation time of the liquid refrigerant recovery operation passes the second predetermined time (for example, 360 seconds), the indoor unit 3 and It is determined that the recovery of the refrigerant staying in the liquid refrigerant pipe 101 has been completed. As with the gas refrigerant recovery operation, the operation time is confirmed in advance by a test, and is set to a time during which the refrigerant staying in the indoor unit 3 and the liquid refrigerant pipe 101 can be recovered according to the installation situation. Then, the outdoor control device 29 closes the liquid refrigerant cutoff valve 51, stops the compressor 21, the outdoor fan 24, and the indoor fan 83, and ends the liquid refrigerant recovery operation.

  The gas refrigerant recovery operation is provided for the first predetermined threshold pressure and the first predetermined time, and the liquid refrigerant recovery operation is provided for the second predetermined threshold pressure, the second predetermined time and the refrigerant recovery operation. Not limited to this, the completion of the refrigerant recovery operation may be determined by setting the first threshold pressure and the second predetermined threshold pressure, and the first predetermined time and the second predetermined time as the same value.

  As described above, in the refrigerant recovery operation, after the indoor expansion valve 81 is closed, the refrigerant recovery operation is performed in the order of the gas refrigerant recovery operation and the liquid refrigerant recovery operation. A refrigerant that stays in the liquid refrigerant pipe 101 without going through the indoor unit 3 after performing a gas refrigerant recovery operation and recovering the refrigerant that stays in the indoor unit 3 and the gas refrigerant pipe 102 before performing a liquid refrigerant recovery operation. Thus, refrigerant leakage into the room can be minimized.

  When performing the above-described refrigerant recovery operation, it is desirable to recover the indoor-side refrigerant in the refrigerant circuit to the outdoor unit 2 as much as possible in order to minimize refrigerant leakage into the room. However, the refrigerant accumulates in the outdoor heat exchanger 23 and the accumulator 26 at the same rate depending on the difference in the internal volume between the outdoor heat exchanger 23 and the accumulator 26 and the state of the recovered refrigerant (ratio of gas refrigerant and liquid refrigerant). Not limited to this, there may be a case where it is biased toward either one. In this case, for example, if the refrigerant recovered in the outdoor unit 2 is biased to the outdoor heat exchanger 23, there is no place in the outdoor heat exchanger 23 where the refrigerant can be recovered. If the compressor 21 is continuously driven in this situation, the compressor 21 Breaks down and refrigerant recovery operation cannot be continued. In order to avoid such a situation, the outdoor heat exchanger 23 became full before the accumulator 26 (for example, 80% or more of the internal volume of the outdoor heat exchanger 23 is filled with the liquid refrigerant). Alternatively, when the accumulator 26 becomes full before the outdoor heat exchanger 23 (for example, 90% or more of the internal volume of the accumulator 26 is filled with liquid refrigerant), the outdoor control device 29 23 or a heat exchanger discharge operation or a surplus refrigerant discharge operation is executed to eliminate the full liquid in the accumulator 26. These heat exchange refrigerant discharge operation and excess refrigerant discharge operation will be described with reference to FIGS. 4 and 5. FIG. 4 shows the open / closed state of each valve during the heat-exchange refrigerant discharge operation. FIG. 5 shows the open / close state of each valve during the surplus refrigerant discharge operation. The open / closed state of each valve is shown in black when it is closed, and white when it is open. Moreover, the flow of the refrigerant at the time of each refrigerant discharge operation is illustrated by a one-dot chain line arrow.

  First, the open / close state of each valve and the flow of the refrigerant in the heat exchanger refrigerant discharge operation will be described.

  When the outdoor heat exchanger 23 is filled with liquid refrigerant during the refrigerant recovery operation, the outdoor control device 29 cannot condense the refrigerant in the outdoor heat exchanger 23 and the pressure on the discharge side of the compressor 21 increases. Therefore, when the discharge pressure detected by the discharge pressure sensor 31 is equal to or higher than a third predetermined threshold pressure (for example, 3.5 MPa), it is determined that the outdoor heat exchanger 23 is full, and the compressor 21 due to an increase in discharge pressure. In order to prevent malfunctions and broken pipes, the refrigerant recovery operation is interrupted and the heat exchange refrigerant discharge operation is performed.

  When the heat-exchange refrigerant discharge operation is performed, the outdoor expansion valve 25 is opened after the liquid refrigerant cutoff valve 51 and the gas refrigerant cutoff valve 52 are closed. Thereby, a refrigerant circuit will be in the state of FIG. 4, and a heat exchange refrigerant | coolant discharge operation is started.

  When the heat-exchange refrigerant discharge operation is started, the refrigerant staying in the outdoor heat exchanger 23 flows as shown by a one-dot chain line arrow shown in FIG. 4 and flows into the accumulator 26. Since the liquid refrigerant shut-off valve 51 and the gas refrigerant shut-off valve 52 are closed, the refrigerant flowing out of the outdoor heat exchanger 23 does not flow into the indoor unit 3, the liquid refrigerant pipe 101, and the gas refrigerant pipe 102, and the outdoor heat The full liquid of the exchanger 23 can be eliminated. If the refrigerant staying in the outdoor heat exchanger 23 flows out, the outdoor control device 29 decreases the discharge pressure. Therefore, when the outdoor control device 29 falls below a fourth predetermined threshold pressure (for example, 3.0 MPa), the outdoor heat exchanger 23 It is determined that the full liquid has been eliminated, the heat exchange refrigerant recovery operation is terminated, and the refrigerant recovery operation is resumed. The third predetermined threshold pressure and the fourth predetermined threshold pressure are obtained in advance by a test, and the discharge pressure is 3.5 MPa, which is a value when 80% of the outdoor heat exchanger 23 is filled with liquid refrigerant. The discharge pressure of 3.0 MPa is a value when 20% of the outdoor heat exchanger 23 is filled with the liquid refrigerant.

  Next, the open / close state of each valve and the flow of the refrigerant will be described for the surplus refrigerant discharge operation.

  When the accumulator 26 is filled with the liquid refrigerant during the refrigerant recovery operation, the outdoor control device 29 starts to flow out of the liquid refrigerant little by little from the accumulator 26, so that the discharge temperature discharged from the compressor 21 decreases and the compression is performed. The degree of superheat on the discharge side of the machine 21 (hereinafter referred to as discharge superheat degree) is reduced. Therefore, the discharge superheat calculated from the difference between the discharge temperature detected by the discharge temperature sensor 41 and the discharge pressure saturation temperature converted from the discharge pressure detected by the discharge pressure sensor 31 is the first predetermined threshold temperature (for example, 4 ° C.). If it becomes below, it will be judged that the accumulator 26 is full, and in order to prevent the failure of the compressor 21 by liquid compression, a refrigerant | coolant collection | recovery operation is interrupted and an excess refrigerant | coolant discharge | release operation is performed.

  When the surplus refrigerant discharge operation is performed, the liquid refrigerant cutoff valve 51 and the gas refrigerant cutoff valve 52 are closed. As a result, the refrigerant circuit enters the state shown in FIG. 5 and the surplus refrigerant discharge operation is started. When the surplus refrigerant discharge operation is performed, an electric heater (not shown) attached to the accumulator 26 is energized.

  When the surplus refrigerant discharge operation is started, the refrigerant staying in the accumulator 26 flows as indicated by a one-dot chain line arrow shown in FIG. 5 and flows into the outdoor heat exchanger 23. At this time, since the liquid refrigerant cutoff valve 51 and the gas refrigerant cutoff valve 52 are closed, there is no refrigerant flowing into the accumulator 26. Further, by heating the accumulator 26 with an electric heater and heating it, a part of the liquid refrigerant staying in the accumulator 26 evaporates to become a gas refrigerant, so that the refrigerant can be discharged from the accumulator 26. In this way, there is no refrigerant flowing into the accumulator 26, and by discharging the refrigerant from the accumulator 26, the full liquid in the accumulator 26 can be eliminated. When the liquid refrigerant staying in the accumulator 26 decreases and the outflow of the liquid refrigerant stops from the accumulator 26, the outdoor control device 29 increases the degree of superheat on the discharge side of the compressor 21, so that the second predetermined threshold temperature (for example, 8 ° C.), it is determined that the full liquid in the accumulator 26 has been eliminated, the surplus refrigerant recovery operation is terminated, and the refrigerant recovery operation is restarted. The first predetermined threshold temperature and the first predetermined threshold temperature are obtained in advance by a test, and the discharge superheat degree is 4 ° C., which is a value when 90% of the accumulator 26 is filled with the liquid refrigerant. The discharge superheat degree of 8 ° C. is a value when 50% of the accumulator 26 is filled with the liquid refrigerant.

  As described above, during the refrigerant recovery operation, if the outdoor heat exchanger 23 becomes full, the heat exchange refrigerant discharge operation is performed, and if the accumulator 26 becomes full, the excess refrigerant discharge operation is performed. The liquid can be eliminated, and the refrigerant recovery operation can be continued. However, for example, when the outdoor heat exchanger 23 becomes full, the heat exchange refrigerant discharge operation is performed and the refrigerant staying in the outdoor heat exchanger 23 flows into the accumulator 26, but the full heat of the outdoor heat exchanger 23 is eliminated. When the accumulator 26 is full before the refrigerant is discharged, if the full heat of the outdoor heat exchanger 23 and the accumulator 26 cannot be eliminated during the heat exchange refrigerant discharge operation or the surplus refrigerant discharge operation, the refrigerant is supplied to the outdoor unit 2. Since there is no recovery place, the refrigerant recovery operation is terminated. Note that the refrigerant recovery operation is also terminated when the outdoor heat exchanger 23 and the accumulator 26 become full at the same time during the refrigerant recovery operation.

  Next, the flow of processing relating to the refrigerant recovery operation will be described using the flowcharts shown in FIGS. 6, 7, and 8. The flowchart shown in FIG. 6 shows the flow of processing related to the refrigerant recovery operation executed by the outdoor control device 29, and FIG. 7 is the subroutine of the flowchart shown in FIG. FIG. 8 is a subroutine of the flowchart shown in FIG. 6 and shows the flow of processing relating to the surplus refrigerant discharge operation. In any flowchart, ST represents a step, and the number following this represents a step number.

  First, the process at the time of refrigerant | coolant collection | recovery driving | operation is demonstrated using FIG.

  The outdoor control device 29 starts the refrigerant recovery operation in response to an input from the refrigerant detection sensor or an instruction from a service person. First, the outdoor control device 29 prepares for a gas refrigerant recovery operation (ST1). In the gas refrigerant recovery operation preparation, the outdoor control device 29 closes the outdoor expansion valve 25, the supercooling expansion valve 28, and the liquid refrigerant cutoff valve 51, and drives the compressor 21 and the outdoor fan 24. In addition, the outdoor control device 29 instructs the indoor control device 84 to close the indoor expansion valve 81 and drive the indoor fan 83.

  Next, the outdoor control device 29 starts timer measurement in order to measure the gas refrigerant recovery operation time (ST2).

  Next, the outdoor control device 29 takes in the pressure / temperature data detected by the discharge pressure sensor 31, the suction pressure sensor 32, and the discharge temperature sensor 41 (ST3). In addition, the outdoor control device 29 fetches and stores pressure / temperature data detected by the discharge pressure sensor 31, the suction pressure sensor 32, and the discharge temperature sensor 41 at regular intervals (for example, every second).

  Next, the outdoor control device 29 determines whether or not the accumulator 26 is full using the pressure / temperature data acquired in ST3 (ST4). If the refrigerant recovery operation is executed while the accumulator 26 is full, a failure due to liquid return to the compressor 21 may occur. In order to avoid this, it is determined first whether or not the accumulator 26 is full, rather than whether or not the outdoor heat exchanger 23 is full. Specifically, the discharge superheat degree that is the difference between the detected value of the discharge temperature sensor 41 taken in and the discharge pressure saturation temperature converted from the detection value of the discharge pressure sensor 31 is 4 ° C. or less of the first predetermined threshold temperature. Whether or not the accumulator 26 is full is determined based on whether or not there is. When the accumulator 26 is full (ST4-Yes), the outdoor control device 29 advances the process to ST19. When the accumulator 26 is not full (ST4-No), the outdoor control device 29 advances the process to ST5.

  When the process proceeds to ST19, it is determined whether or not the outdoor heat exchanger 23 is full using the pressure / temperature data taken in ST3. Specifically, it is determined whether or not the outdoor heat exchanger 23 is full based on whether or not the discharge pressure detected by the taken-in discharge pressure sensor 31 is equal to or higher than the third predetermined threshold pressure of 3.5 MPa. . When the outdoor heat exchanger 23 is full (ST19-Yes), the outdoor heat exchanger 23 and the accumulator 26 are full at the same time, and no further refrigerant recovery operation can be performed. The expansion valve 28, the liquid refrigerant shut-off valve 51, and the gas refrigerant shut-off valve 52 are closed, the compressor 21 and the outdoor fan 24 are stopped, the refrigerant recovery operation is finished, and the processing related to the present invention is finished. When the outdoor heat exchanger 23 is not full (ST19-No), the outdoor control device 29 temporarily stops the refrigerant recovery operation, performs the excess refrigerant discharge operation (ST20), and proceeds to ST16.

  When the process proceeds to ST5, it is determined whether or not the outdoor heat exchanger 23 is in a state filled with the liquid refrigerant using the pressure / temperature data taken in ST3. Specifically, it is determined whether or not the outdoor heat exchanger 23 is full based on whether or not the discharge pressure detected by the taken-in discharge pressure sensor 31 is equal to or higher than the third predetermined threshold pressure of 3.5 MPa. . When the outdoor heat exchanger 23 is full (ST5-Yes), the outdoor control device 29 temporarily interrupts the refrigerant recovery operation, performs the heat exchanger discharge operation (ST15), and proceeds to ST16. When the outdoor heat exchanger 23 is not full (ST5-No), the outdoor control device 29 continues the refrigerant recovery operation and advances the process to ST6.

  In ST16, the outdoor control device 29 determines whether or not a full liquid flag to be described later is “0”. When the full liquid flag is “0”, the full liquid in the outdoor heat exchanger 23 or the accumulator 26 has been eliminated by performing the heat exchanger refrigerant discharge operation (ST15) or the surplus refrigerant discharge operation (ST20). In the case of the full liquid flag “1”, the full liquid in the outdoor heat exchanger 23 and the accumulator 26 could not be resolved even if the heat exchanger refrigerant discharge operation (ST15) or the surplus refrigerant discharge operation (ST20) was performed. Represents that. If the full liquid flag is “0” (ST16-Yes), the outdoor control device 29 advances the process to ST6. If the full liquid flag is “1” (ST16-No), the outdoor control device 29 ends the refrigerant recovery operation and ends the processing relating to the present invention.

  Next, the outdoor control device 29 determines whether or not the recovery of the gas refrigerant has been completed. This is to determine whether or not the refrigerant staying in the indoor unit 3 and the gas refrigerant pipe 102 has been recovered in the outdoor unit 2. Specifically, the suction pressure detected by the suction pressure sensor 32 taken in is the first. Whether or not the recovery of the gas refrigerant is completed depending on whether or not the predetermined threshold pressure of 1 is 0.05 MPa or less, or whether or not 180 seconds of the first predetermined time have elapsed since the timer measurement in ST2. to decide. If the recovery of the gas refrigerant has been completed (ST6-Yes), the outdoor control device 29 closes the gas refrigerant cutoff valve 52 and ends the gas refrigerant recovery operation (ST7). If the recovery of the gas refrigerant has not been completed (ST6-No), the outdoor control device 29 returns the process to ST3 and continues the gas refrigerant recovery operation.

  When the gas refrigerant recovery operation is finished, the outdoor control device 29 next prepares for the liquid refrigerant recovery operation (ST8). In the liquid refrigerant recovery operation preparation, the outdoor control device 29 opens the supercooling expansion valve 28 and the liquid refrigerant cutoff valve 51.

  Next, the outdoor control device 29 starts timer measurement in order to measure the liquid refrigerant recovery operation time (ST9).

  Next, the outdoor control device 29 performs a process for taking in pressure / temperature data detected by the discharge pressure sensor 31, the suction pressure sensor 32, and the discharge temperature sensor 41 (ST10).

  Next, the outdoor control device 29 determines whether or not the outdoor heat exchanger 23 and the accumulator 26 are full using the pressure / temperature data acquired in ST10. Note that ST11, ST12, ST17, ST18, ST21, and ST22, which are processes related to this determination, are the same as ST4, ST5, ST15, ST16, ST19, and ST20 described above, and thus detailed description thereof is omitted. To do.

  When it is determined in ST12 that the outdoor heat exchanger 23 is not full (ST12-No) or the refrigerant recovery operation can be resumed in ST18 (ST18-Yes), the process proceeds to ST13, and then the outdoor control device 29 determines whether the recovery of the liquid refrigerant has been completed. This is to determine whether or not the refrigerant staying in the liquid refrigerant pipe 101 can be collected in the outdoor unit 2. Specifically, the suction pressure detected by the suction pressure sensor 32 taken in is a second predetermined threshold value. It is determined whether or not the recovery of the liquid refrigerant is completed depending on whether or not the pressure is 0.05 MPa or less or whether or not 360 seconds of the second predetermined time have elapsed since the start of the timer measurement in ST9. . If the recovery of the liquid refrigerant is completed (ST13-Yes), the outdoor control device 29 closes the supercooling expansion valve 28 and the liquid refrigerant shut-off valve 51, and stops the compressor 21 and the outdoor fan 24. Then, the liquid refrigerant recovery operation is terminated (ST14). If the recovery of the liquid refrigerant has not been completed (ST13-No), the outdoor control device 29 returns the process to ST10 and continues the liquid refrigerant recovery operation.

  Next, the heat exchanger discharge operation performed in ST15 or ST17 in FIG. 6 will be described with reference to FIG.

  First, the outdoor control device 29 prepares for a heat exchange refrigerant discharge operation (ST101). Specifically, in order to interrupt the refrigerant recovery operation, the liquid refrigerant shut-off valve 51 and the gas refrigerant shut-off valve 52 are closed, and the outdoor expansion valve 25 is opened in order to discharge the refrigerant staying in the outdoor heat exchanger 23.

  Next, the outdoor control device 29 takes in the pressure / temperature data detected by the discharge pressure sensor 31, the suction pressure sensor 32, and the discharge temperature sensor 41 (ST102).

  Next, the outdoor control device 29 determines whether or not the liquid refrigerant in the outdoor heat exchanger 23 has been discharged (ST103). Specifically, it is determined whether or not the liquid refrigerant in the outdoor heat exchanger 23 has been discharged depending on whether or not the discharge pressure detected by the taken-in discharge pressure sensor 31 is not more than the fourth predetermined threshold pressure of 3.0 MPa. To do. When the liquid refrigerant in the outdoor heat exchanger 23 is discharged (ST103-Yes), the outdoor control device 29 can eliminate the full liquid in the outdoor heat exchanger 23, and therefore sets the full liquid flag to “0” (ST104). When the outdoor expansion valve 25 is closed and the heat exchanger discharge operation is performed during the gas refrigerant recovery operation (ST15 in FIG. 6), the gas refrigerant shut-off valve 52 is opened and the liquid refrigerant recovery operation (ST17 in FIG. 6). When performing the heat exchanger refrigerant discharge operation, the liquid refrigerant shut-off valve 51 is opened to end the heat exchanger refrigerant discharge operation. When the liquid refrigerant in the outdoor heat exchanger 23 is not discharged (ST103-No), the outdoor control device 29 advances the process to ST105.

  In ST105, the outdoor control device 29 determines whether or not the accumulator 26 is full. Specifically, whether or not the accumulator 26 is full is determined based on whether or not the discharge superheat degree is 4 ° C. or less, which is the first predetermined threshold temperature. If the accumulator 26 is full (ST105-Yes), the outdoor control device 29 has not been able to eliminate the full liquid in the outdoor heat exchanger 23 and the accumulator 26, so the full liquid flag is set to “1” (ST106). Then, the heat exchanger refrigerant discharge operation is terminated. When the accumulator 26 is not full (ST105-No), the outdoor control device 29 returns the process to ST102 and continues the heat exchange refrigerant discharge operation.

  Next, the surplus refrigerant discharge operation performed in ST20 or ST22 of FIG. 6 will be described with reference to FIG.

  First, the outdoor control device 29 prepares for excess refrigerant discharge operation (ST201). Specifically, in order to interrupt the refrigerant recovery operation, the liquid refrigerant cutoff valve 51 and the gas refrigerant cutoff valve 52 are closed. At this time, the outdoor control device 29 starts energizing an electric heater (not shown) attached to the accumulator 26.

  Next, the outdoor control device 29 takes in the pressure / temperature data detected by the discharge pressure sensor 31, the suction pressure sensor 32, and the discharge temperature sensor 41 (ST202).

  Next, the outdoor control device 29 determines whether or not the liquid refrigerant in the accumulator 26 has been discharged. (ST203). Specifically, the discharge superheat degree that is the difference between the detected value of the discharged discharge temperature sensor 41 and the discharge pressure saturation temperature converted from the detected value of the discharge pressure sensor 31 is equal to or higher than the second predetermined threshold temperature of 8 ° C. Whether or not the liquid refrigerant in the accumulator 26 has been discharged. When the liquid refrigerant in the accumulator 26 has been discharged (ST203-Yes), the outdoor control device 29 has cleared the full liquid in the accumulator 26, so the full liquid flag is set to “0” (ST204) and attached to the accumulator 26. When the electric heater (not shown) is turned off and the surplus refrigerant recovery operation is performed during the gas refrigerant recovery operation (ST20 in FIG. 6), the gas refrigerant shut-off valve 52 is opened and the liquid refrigerant recovery operation is performed (ST22 in FIG. 6). When the surplus refrigerant recovery operation is performed, the liquid refrigerant shut-off valve 51 is opened to end the surplus refrigerant discharge operation. When the liquid refrigerant in the accumulator 26 has not been discharged (ST203—No), the outdoor control device 29 advances the process to ST205.

  In ST205, the outdoor control device 29 determines whether or not the outdoor heat exchanger 23 is full. Specifically, it is determined whether or not the outdoor heat exchanger 23 is full based on whether or not the discharge pressure is equal to or higher than the third predetermined threshold pressure of 3.5 MPa. When the outdoor heat exchanger 23 is full (ST205-Yes), the outdoor control device 29 has not been able to eliminate the full liquid in the outdoor heat exchanger 23 and the accumulator 26, so the full liquid flag is set to “1” (ST206). ), The energization of the electric heater (not shown) attached to the accumulator 26 is stopped, and the surplus refrigerant discharge operation is terminated. When the outdoor heat exchanger 23 is not full (ST205-No), the outdoor control device 29 returns the process to ST202. Continue surplus refrigerant discharge operation.

  As described above, according to the present embodiment, the refrigerant staying in the liquid refrigerant pipe 101 without using the indoor unit 3 can be collected in the outdoor unit 2. Further, by performing the refrigerant discharge operation, the fullness of the outdoor heat exchanger 23 or the accumulator 26 is eliminated, and the refrigerant recovery operation can be continued, so that it is possible to recover as much refrigerant as possible staying indoors in the refrigerant circuit, The amount of refrigerant leakage into the room can be reduced.

  In this embodiment, whether or not the outdoor heat exchanger 23 is full is determined using the discharge pressure. However, the present invention is not limited to this. For example, a plurality of temperature sensors are attached to the outdoor heat exchanger 23. It may be determined whether or not the outdoor heat exchanger 23 is full using detection values of a plurality of temperature sensors. Whether or not the accumulator 26 is full is determined using the discharge superheat degree. However, the present invention is not limited to this. For example, the accumulator is detected using the detection value of the discharge temperature sensor 41 or the detection value of the suction temperature sensor 42. It may be determined whether or not 26 is full.

  Next, a second embodiment of the air conditioner 1 according to the present invention will be described. In this embodiment, the operation of each valve and its effect by the refrigerant recovery operation are the same as those in the first embodiment, and thus detailed description thereof is omitted. The difference from the first embodiment is that the gas refrigerant shutoff valve 52 is a check valve 53.

  FIG. 9 shows a refrigerant circuit configuration of the air conditioner 1 according to the second embodiment. In FIG. 9, the gas refrigerant shutoff valve 52 described in FIG. 1 is eliminated, and the port c of the four-way valve 22 is connected between the port c of the refrigerant pipe connecting the port c of the four-way valve 22 and the accumulator 26 and the junction 62. A check valve 53 is attached in the direction in which the refrigerant flows to the accumulator 26. Due to the function of the check valve 53, the refrigerant staying in the liquid refrigerant pipe 101 during the liquid refrigerant recovery operation is joined from the first bypass pipe 27a, the cooling side pipe 27d of the supercooling heat exchanger 27, and the second bypass pipe 27b. The refrigerant does not flow out into the indoor unit 3 and the gas refrigerant pipe 102 through the 62 and the four-way valve 22, and the refrigerant does not leak into the room.

  In the embodiment described above, the gas refrigerant shut-off valve 52 is the check valve 53, so that the present invention can be implemented with a cheaper configuration. Further, there is no open / close control of the gas refrigerant shutoff valve 52 by the outdoor control device 29, and the control related to the refrigerant recovery operation can be further simplified.

  As described above, since the air conditioner of the present invention can collect the refrigerant staying in the liquid refrigerant pipe without passing through the indoor unit in the outdoor unit, even if a refrigerant leak occurs in the indoor unit, it can be taken indoors. The refrigerant leakage can be minimized. Further, by allowing the refrigerant to stay in the accumulator in addition to the outdoor heat exchanger, the refrigerant recovery operation can be performed reliably even in an air conditioner having a large amount of enclosed refrigerant.

  In the embodiment described above, the description has been given in the order in which the liquid refrigerant recovery operation is performed after the gas refrigerant recovery operation is performed. However, the present invention is not limited to this, and when the refrigerant leaks from the liquid refrigerant pipe The gas refrigerant recovery operation may be performed after the liquid refrigerant recovery operation. If the order in which the gas refrigerant recovery operation and the liquid refrigerant recovery operation are performed in accordance with the refrigerant leakage portion is determined, the amount of refrigerant leakage into the room can be further reduced. Moreover, the amount of refrigerant leaking into the room can be reduced only by performing either the gas refrigerant recovery operation or the liquid refrigerant recovery operation. Further, the same effect can be obtained when the present invention is implemented not only with a cooling / heating switching type air conditioner including a four-way valve but also with an air conditioner dedicated to cooling. Further, the refrigerant in the liquid refrigerant pipe is recovered via the supercooling heat exchanger, but the present invention is not limited to this, and in an air conditioner that does not include the supercooling heat exchanger, the outdoor expansion valve and the liquid A bypass circuit having a refrigerant recovery on-off valve similar to the cooling side piping, the first bypass pipe, and the second bypass pipe of the supercooling heat exchanger that bypasses between the refrigerant cutoff valves and between the gas refrigerant cutoff valve and the accumulator. The structure provided with may be sufficient. Moreover, it is not necessary to provide a bypass circuit, a liquid refrigerant | coolant cutoff valve, and a gas refrigerant cutoff valve in an outdoor unit, You may provide these structures in the middle of each connection piping, or between an outdoor unit and each connection piping.

  In the embodiment described above, the case where the refrigerant is evaporated using the electric heater attached to the accumulator during the surplus refrigerant discharge operation has been described. However, the accumulator can be obtained by causing the high-temperature refrigerant discharged from the compressor to flow into the accumulator. The refrigerant staying in the tank may be evaporated, for example, having a bypass circuit having a bypass pipe and an on-off valve that bypasses between the compressor and the outdoor heat exchanger, and between the gas refrigerant shut-off valve and the accumulator. Alternatively, the refrigerant may be evaporated by opening the on-off valve so that the high-temperature refrigerant discharged from the compressor flows into the accumulator.

DESCRIPTION OF SYMBOLS 1 Air conditioner 2 Outdoor unit 3 Indoor unit 21 Compressor 22 Four-way valve 23 Outdoor heat exchanger 24 Outdoor fan 25 Outdoor expansion valve 26 Accumulator 27 Supercooling heat exchanger 27a First bypass pipe 27b Second bypass pipe 27c Cooled side Pipe 27d Cooling side pipe 28 Supercooling expansion valve 31 Discharge pressure sensor 32 Suction pressure sensor 41 Discharge temperature sensor 42 Suction temperature sensor 51 Liquid refrigerant shutoff valve 52 Gas refrigerant shutoff valve 53 Check valve 81 Indoor expansion valve 101 Liquid refrigerant pipe 102 Gas Refrigerant piping

Claims (6)

An air in which an outdoor unit having a compressor, an outdoor heat exchanger, an outdoor open / close valve, and an accumulator, and an indoor unit having an indoor heat exchanger and an indoor open / close valve are connected by a liquid refrigerant pipe and a gas refrigerant pipe. A harmony machine,
The air conditioner includes a liquid refrigerant blocking mechanism that can block a refrigerant flow in the liquid refrigerant pipe, a gas refrigerant blocking mechanism that can block a refrigerant flow in the gas refrigerant pipe, the outdoor on-off valve, and the liquid A bypass circuit having a refrigerant recovery on-off valve that bypasses between the refrigerant shut-off mechanism and between the gas refrigerant shut-off mechanism and the accumulator, and a control means for performing on-off control of each of the refrigerant shut-off mechanisms and all the on-off valves; Have
When the control means executes a refrigerant recovery operation for recovering the refrigerant in the outdoor unit,
A gas refrigerant recovery operation in which the liquid refrigerant shut-off mechanism is closed, the gas refrigerant shut-off mechanism is opened, and the refrigerant staying in the indoor unit and the gas refrigerant pipe is recovered; and / or
There is a liquid refrigerant recovery operation in which the gas refrigerant shut-off mechanism is closed, the liquid refrigerant shut-off mechanism is opened, and the refrigerant staying in the liquid refrigerant pipe is recovered.
An air conditioner characterized by that. The outdoor unit further includes a flow path switching means for switching the refrigerant discharged from the compressor to flow to the outdoor heat exchanger or the indoor heat exchanger,
In place of the gas refrigerant shut-off mechanism, a check valve is provided,
The check valve is provided in a refrigerant pipe connecting the flow path switching means and the accumulator, and is arranged so that the refrigerant flows from the flow path switching means toward the accumulator, and one end of the bypass circuit is Connect to the check valve outflow side,
The air conditioner according to claim 1. When the refrigerant recovery operation is executed when the refrigerant leaks in the indoor unit or the gas refrigerant pipe, the control unit starts the gas refrigerant recovery operation first and performs the liquid refrigerant recovery operation later. ,
The air conditioner according to claim 1 or 2, characterized by the above. The control means starts the liquid refrigerant recovery operation first and performs the gas refrigerant recovery operation later when performing the refrigerant recovery operation when a refrigerant leak occurs in the liquid refrigerant pipe.
The air conditioner according to claim 1 or 2, characterized by the above. The outdoor unit has suction pressure detection means for detecting suction pressure on the suction side of the compressor;
The control means ends the gas refrigerant recovery operation when the suction pressure detected by the suction pressure detection means is equal to or lower than a first predetermined threshold pressure during the gas refrigerant recovery operation. When the liquid refrigerant recovery operation is being performed, if the suction pressure detected by the suction pressure detection means is equal to or lower than a second predetermined threshold pressure, the liquid refrigerant recovery operation is terminated.
The air conditioner according to any one of claims 1 to 4, wherein: The control means measures the operation time of the gas refrigerant recovery operation or the liquid refrigerant recovery operation, and ends the gas refrigerant recovery operation when the operation time of the gas refrigerant recovery operation has passed the first predetermined time. When the operation time of the liquid refrigerant recovery operation has passed the second predetermined time, the liquid refrigerant recovery operation is terminated.
The air conditioner according to any one of claims 1 to 4, wherein:

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