JP2015087071A - Air conditioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an air conditioner which, even in an air conditioner having a large sealed refrigerant amount, solves a state where one of an outdoor heat exchanger and an accumulator becomes full with a liquid during a refrigerant recovery operation, and which can continue the refrigerant recovery operation.SOLUTION: While a refrigerant recovery operation is being performed for recovering a refrigerant to an outdoor unit 2 including a plurality of refrigerant recovery parts, a refrigerant recovery amount recovered at least in one of the refrigerant recovery parts becomes equal to or more than an allowable refrigerant recovery amount which can be recovered in the refrigerant recovery part, the refrigerant recovery operation is interrupted, and the staying refrigerant is discharged to other refrigerant recovery parts from the refrigerant recovery part in which the refrigerant recovery amount is equal to or more than the allowable amount. The refrigerant staying in the refrigerant recovery part is discharged to a predetermined amount or less, the refrigerant recovery operation is resumed.

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, all of the refrigerant recovered in the outdoor unit by the refrigerant recovery operation is stored in the outdoor heat exchanger. On the other hand, when the air conditioner is a large air conditioner installed in a building or the like, the amount of refrigerant sealed in the refrigerant circuit may be larger than the amount of refrigerant that can be stored in the outdoor heat exchanger. In this case, there is a possibility that the refrigerant that cannot be recovered by the outdoor heat exchanger remains in the refrigerant circuit, and the remaining refrigerant leaks from the refrigerant circuit, increasing the amount of refrigerant leakage.

  Therefore, it is conceivable to prepare a place where the refrigerant can be collected in addition to the outdoor heat exchanger to increase the refrigerant collection amount. For example, an accumulator connected to the suction side of the compressor is added to the outdoor heat exchanger to collect the refrigerant. Can be considered as a part. However, the outdoor heat exchanger and the accumulator have different internal volumes, and during the refrigerant recovery operation, the outdoor heat exchanger becomes the discharge side of the compressor, the accumulator becomes the suction side of the compressor, etc. There is a risk that either the exchanger or the accumulator will exceed the allowable refrigerant recovery amount (hereinafter referred to as full liquid) that can recover the refrigerant to the outdoor heat exchanger or accumulator.

  If the outdoor heat exchanger becomes full, the pressure on the discharge side of the compressor may rise and the compressor may stop due to discharge pressure protection. If the accumulator is full, the liquid refrigerant flowing out of the accumulator may be sucked into the compressor to cause liquid compression and the compressor may be damaged. That is, if either the outdoor heat exchanger or the accumulator is full, there is a possibility that the refrigerant recovery operation cannot be continued.

  The present invention provides an air conditioner that solves the above-mentioned problems, eliminates the state in which either the outdoor heat exchanger or the accumulator is full during the refrigerant recovery operation, and can continue the refrigerant recovery operation. Objective.

  In order to solve the above problems, an air conditioner of the present invention is an air conditioner having an outdoor unit having a plurality of refrigerant recovery units, an indoor unit, and a control means, and the refrigerant of the air conditioner When it is determined that the refrigerant recovery amount recovered by at least one refrigerant recovery unit is equal to or greater than the allowable refrigerant recovery amount recoverable by the refrigerant circuit unit when performing the refrigerant recovery operation of recovering to a plurality of refrigerant recovery units Then, after the refrigerant recovery operation is interrupted and the refrigerant staying in at least one refrigerant recovery unit is discharged from the refrigerant recovery unit, the refrigerant recovery operation is resumed.

  According to the air conditioner of the present invention configured as described above, the state in which either the outdoor heat exchanger or the accumulator becomes full during the refrigerant recovery operation is eliminated, and the refrigerant recovery operation can be continued.

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. It is a refrigerant circuit diagram of the air conditioner which is Example 3 of this invention, and is a refrigerant circuit diagram which shows the open / close state of the valve at the time of the excess refrigerant | coolant discharge operation in Example 3, and the flow of a refrigerant | coolant. It is a refrigerant circuit figure of the air conditioner which is Example 4 of this invention, and is a refrigerant circuit figure which shows the open / close state of the valve at the time of the heat exchanger refrigerant | coolant discharge operation in Example 4, and the flow of a refrigerant | coolant.

  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 as a refrigerant recovery on-off valve, a liquid refrigerant cutoff valve 51 as a liquid refrigerant cutoff mechanism, a gas refrigerant cutoff valve 52 as a gas refrigerant cutoff mechanism, an indoor expansion valve 81, The indoor unit 3 having the heat exchanger 82 and the indoor fan 83, the liquid refrigerant pipe 101 and the gas refrigerant pipe 102 connecting the outdoor unit 2 and the indoor unit 3, and the components other than the outdoor fan 24 and the indoor fan 83 are mutually connected. A refrigerant circuit is formed by being connected to each other by a refrigerant pipe.

  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 the gas refrigerant recovery operation is performed, the outdoor control device 29 periodically takes in the suction pressure detected by the suction pressure sensor 32, and the gas refrigerant recovery operation end threshold (for example, the taken-in suction pressure is a predetermined value) (for example, , 0.01 MPa) or less, it is determined that the recovery of the refrigerant staying in the indoor unit 3 and the gas refrigerant pipe 102 has been 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 gas refrigerant recovery operation end threshold value. Therefore, the outdoor control device 29 measures the operation time after starting the gas refrigerant recovery operation. Then, if the gas refrigerant recovery operation end threshold time (for example, 180 seconds), which is the predetermined time of the gas refrigerant recovery operation, has elapsed, recovery of the refrigerant staying in the indoor unit 3 and the gas refrigerant pipe 102 is completed. to decide. 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 liquid refrigerant recovery operation end threshold value (in which the taken-in suction pressure is a predetermined value) For example, if the pressure is 0.05 MPa or less, it is determined that the recovery of the refrigerant staying in the liquid refrigerant pipe 101 is 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 fall below the liquid refrigerant recovery operation end threshold, the liquid refrigerant recovery operation end threshold time (for example, 360 seconds), which is the predetermined time of the liquid refrigerant recovery operation, elapses. For example, it is determined that the recovery of the refrigerant staying in the indoor unit 3 and the liquid refrigerant pipe 101 is 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.

  For gas refrigerant recovery operation, gas refrigerant recovery operation end threshold and gas refrigerant recovery operation end threshold time, and for liquid refrigerant recovery operation, liquid refrigerant recovery operation end threshold and liquid refrigerant recovery operation end threshold time, and for each refrigerant recovery operation. However, the present invention is not limited to this, and the completion of the refrigerant recovery operation is determined by setting the gas refrigerant recovery operation end threshold and the liquid refrigerant recovery operation end threshold, the gas refrigerant recovery operation end threshold time, and the liquid refrigerant recovery operation end threshold time to the same value. May be.

  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, either one may become full first. In this case, for example, when the outdoor heat exchanger 23 becomes full first, there is no place where the refrigerant can be recovered in the outdoor heat exchanger 23. If the compressor 21 is continuously driven in this situation, the compressor 21 breaks down. The refrigerant recovery operation cannot be continued. In order to avoid such a situation, the outdoor heat exchanger 23 is full before the accumulator 26 (for example, 80% of the internal volume of the outdoor heat exchanger 23 (the allowable refrigerant of the outdoor heat exchanger 23). Or more, the accumulator 26 is full before the outdoor heat exchanger 23 (for example, 90% of the internal volume of the accumulator 26 (the allowable refrigerant recovery amount of the accumulator 26). When the above is filled with the liquid refrigerant), the outdoor control device 29 executes a heat exchange refrigerant discharge operation or a surplus refrigerant discharge operation in order to eliminate the full liquid in the outdoor heat exchanger 23 or 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. In this embodiment, the discharge pressure is used as the operating state variable that varies depending on the variation in the amount of refrigerant that stays in the outdoor heat exchanger 23, which indicates whether or not the outdoor heat exchanger 23 is full. To do.

  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 first predetermined threshold (for example, 3.5 MPa), it is determined that the outdoor heat exchanger 23 is full, and the compressor 21 due to the increase in the discharge pressure is determined. In order to prevent failure and pipe breakage, 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. When 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 the second predetermined threshold (for example, 3.0 MPa), the outdoor heat exchanger 23 is fully charged. It is determined that the liquid has been eliminated, the heat exchanger recovery operation is terminated, and the coolant recovery operation is restarted. The first predetermined threshold and the second predetermined threshold are obtained in advance by a test, and the discharge pressure of 3.5 MPa is a value when 80% of the outdoor heat exchanger 23 is filled with the 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. In the present embodiment, the discharge superheat degree is described as an operation state amount that varies depending on the variation in the amount of refrigerant that stays in the accumulator 26 that indicates whether or not the accumulator 26 is full.

  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 a third predetermined threshold (for example, 4 ° C.) or less. Then, it is determined that the accumulator 26 is full, and the refrigerant recovery operation is interrupted and the excess refrigerant discharge operation is performed in order to prevent the compressor 21 from being broken due to liquid compression.

  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. When the temperature reaches 8 ° C. or higher, it is determined that the accumulator 26 has been completely filled, the surplus refrigerant recovery operation is terminated, and the refrigerant recovery operation is restarted. The third predetermined threshold value and the fourth predetermined threshold value are obtained in advance in a test, and the discharge superheat degree is 4 ° C., which is a value when 90% of the accumulator 26 is filled with liquid refrigerant. The 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 unit, 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, which is the difference between the detected value of the discharged discharge temperature sensor 41 and the discharge pressure saturation temperature converted from the detection value of the discharge pressure sensor 31, is 4 ° C. or less, which is a third predetermined threshold value. Whether or not the accumulator 26 is full. 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, whether or not the outdoor heat exchanger 23 is full is determined based on whether or not the discharge pressure detected by the taken-in discharge pressure sensor 31 is equal to or higher than the first predetermined threshold value 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, whether or not the outdoor heat exchanger 23 is full is determined based on whether or not the discharge pressure detected by the taken-in discharge pressure sensor 31 is equal to or higher than the first predetermined threshold value 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 taken-in suction pressure sensor 32 is the gas. Whether or not the recovery of the gas refrigerant is completed depending on whether or not the refrigerant recovery operation end threshold value is 0.05 MPa or less, or whether the gas refrigerant recovery operation end threshold time of 180 seconds has elapsed since the timer measurement in ST2. Determine whether. 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 has been collected in the outdoor unit 2, and specifically, the suction pressure detected by the taken-in suction pressure sensor 32 is the end of the liquid refrigerant collection operation. Whether or not the recovery of the liquid refrigerant is completed depending on whether or not the threshold value is 0.05 MPa or less, or whether or not the liquid refrigerant recovery operation end threshold time has elapsed after starting the timer measurement in ST9. to decide. 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 based on whether or not the discharge pressure detected by the taken-in discharge pressure sensor 31 is equal to or lower than the second predetermined threshold value of 3.0 MPa. . 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, it is determined whether or not the accumulator 26 is full based on whether or not the discharge superheat degree is 4 ° C. or less, which is a third predetermined threshold value. 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, whether the discharge superheat degree, which 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 equal to or higher than the fourth predetermined threshold value of 8 ° C. It is determined 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 first predetermined threshold 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, the case where the discharge pressure is used as the operating state quantity that varies depending on the fluctuation of the refrigerant amount staying in the outdoor heat exchanger 23, which indicates whether or not the outdoor heat exchanger 23 is full. Although described above, the present invention is not limited to this. For example, a plurality of temperature sensors are attached to the outdoor heat exchanger 23, and the liquid level in the outdoor heat exchanger 23 is detected using detection values of the plurality of temperature sensors. It may be determined whether or not the outdoor heat exchanger 23 is full. Moreover, although the case where discharge superheat degree is used as an operation state quantity which fluctuates according to the fluctuation | variation of the refrigerant | coolant amount which retains in the accumulator 26 which shows whether the accumulator 26 is full was demonstrated, it is not restricted to this, For example, Alternatively, it may be determined whether the accumulator 26 is full using the detection value of the discharge temperature sensor 41 or the detection value of the suction temperature sensor 42.

  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.

  Next, a third embodiment of the air conditioner 1 according to the present invention will be described with reference to FIG. In the third embodiment, instead of heating the refrigerant by the electric heater during the surplus refrigerant discharge operation described in the first embodiment, the high-temperature refrigerant discharged from the compressor 21 is used for discharging the surplus refrigerant to the accumulator 26. A bypass circuit is provided to heat the refrigerant by allowing a high-temperature refrigerant to flow into the accumulator 26. In the present embodiment, the configuration other than the configuration of the surplus refrigerant discharge bypass circuit and the operation of the refrigerant circuit during the surplus refrigerant discharge operation are the same as those in the first embodiment, and thus detailed description thereof is omitted.

  FIG. 10 shows a refrigerant circuit configuration of the air conditioner 1 according to the third embodiment. The refrigerant circuit shown in FIG. 10 has the refrigerant circuit configuration described in FIG. 1 and an excess refrigerant discharge pipe 71 that bypasses between the compressor 21 and the outdoor heat exchanger 23, and between the accumulator 26 and the gas refrigerant shut-off valve 52. And a surplus refrigerant discharge opening / closing valve 72 provided in the middle thereof. The surplus refrigerant discharge pipe 71 and the surplus refrigerant discharge open / close valve 72 constitute a surplus refrigerant discharge bypass circuit.

  When the outdoor control device 29 determines that the accumulator 26 is full, the refrigerant recovery operation is interrupted and the surplus refrigerant discharge operation is performed. When the surplus refrigerant discharge operation is performed, the outdoor control device 29 closes the liquid refrigerant shut-off valve 51 and the gas refrigerant shut-off valve 52 and opens the surplus refrigerant discharge on-off valve 72. Then, the outdoor control device 29 starts a surplus refrigerant discharge operation. When the surplus refrigerant discharge operation is started, a part of the high-temperature refrigerant discharged from the compressor 21 flows as shown by a one-dot chain line arrow shown in FIG. 10 and flows into the accumulator 26. When the high-temperature refrigerant flows into the accumulator 26, the liquid refrigerant staying in the accumulator 26 is heated to become a gas refrigerant and is discharged from the accumulator 26, so that the accumulator 26 is completely filled. When the outdoor control device 29 determines that the full liquid in the accumulator 26 has been eliminated, it closes the surplus refrigerant discharge on-off valve 72, ends the surplus refrigerant discharge operation, and restarts the refrigerant recovery operation.

  In the embodiment described above, since the liquid refrigerant staying in the accumulator 26 is heated by the surplus refrigerant discharge bypass circuit, it is not necessary to heat the accumulator 26 with an electric heater, and the power consumption during the operation of discharging the surplus refrigerant is suppressed. be able to.

  Next, a fourth embodiment of the air conditioner 1 according to the present invention will be described with reference to FIG. In the fourth embodiment, the refrigerant circuit shown in FIG. 1 is provided with a bypass circuit for discharging a heat exchanger that bypasses between the accumulator 26 and the gas refrigerant shut-off mechanism 52 from between the outdoor heat exchanger 23 and the outdoor expansion valve 25. Is added. In this embodiment, since the configuration of the heat exchanger refrigerant discharge bypass circuit and the operation of the refrigerant circuit during the heat exchanger coolant discharge operation are the same as those in the first embodiment, detailed description thereof will be omitted.

  FIG. 11 shows a refrigerant circuit configuration of the air conditioner 1 according to the fourth embodiment. The refrigerant circuit shown in FIG. 11 is similar to the refrigerant circuit configuration described in FIG. 1 except that the heat exchange refrigerant discharge bypasses between the outdoor heat exchanger 23 and the outdoor expansion valve 25, and between the accumulator 26 and the gas refrigerant shut-off valve 52. A pipe 73 and a heat exchanger discharge opening / closing valve 74 provided in the middle of the pipe 73 are added. The heat exchanger refrigerant discharge pipe 73 and the heat exchanger refrigerant discharge on-off valve 74 constitute a heat exchanger refrigerant discharge bypass circuit.

  When the outdoor control device 29 determines that the outdoor heat exchanger 23 is full, the heat exchanger discharge operation is performed. When the heat exchange refrigerant discharge operation is performed, the outdoor control device 29 opens the heat exchange refrigerant discharge on-off valve 74. Then, the outdoor control device 29 starts the heat exchange refrigerant discharge operation. When the heat exchange refrigerant discharge operation is started, the refrigerant staying in the outdoor heat exchanger 23 flows as indicated by a one-dot chain line arrow shown in FIG. 11 and flows into the accumulator 26, and the full liquid in the outdoor heat exchanger 23 is eliminated. The If the outdoor control device 29 determines that the full liquid in the outdoor heat exchanger 23 has been eliminated, the outdoor heat exchanger 23 closes the heat exchanger coolant discharge on-off valve 74 and ends the heat exchanger coolant discharge operation.

  In the embodiment described above, since the refrigerant staying in the outdoor heat exchanger 23 is caused to flow out by the heat exchanger refrigerant discharge bypass circuit, the outdoor heat exchanger 23 is operated while performing the liquid refrigerant recovery operation described in the first embodiment. The liquid refrigerant staying in can be discharged, and the full liquid in the outdoor heat exchanger 23 can be eliminated without interrupting the liquid refrigerant recovery operation. If full liquid in the outdoor heat exchanger 23 can be eliminated without interrupting the liquid refrigerant recovery operation, the liquid refrigerant recovery operation can be performed in a short time, and the amount of refrigerant leakage can be reduced.

  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, when the refrigerant is evaporated using an electric heater attached to the accumulator during the surplus refrigerant discharge operation, and when the high-temperature refrigerant discharged from the compressor flows into the accumulator, the refrigerant stays in the accumulator. However, a high-temperature refrigerant may be allowed to flow in while being heated by an electric heater. Although the power consumption is increased, the refrigerant recovery operation can be completed in a short time and the amount of refrigerant leakage can be reduced as much as the excess refrigerant discharge operation is completed in a short time.

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 71 Surplus refrigerant discharge pipe 72 For surplus refrigerant discharge On-off valve 73 Heat exchange refrigerant discharge pipe 74 Heat exchange refrigerant discharge on-off valve 81 Indoor expansion valve 101 Liquid refrigerant piping 102 Gas refrigerant piping

Claims (4)

An air conditioner having an outdoor unit having a plurality of refrigerant recovery units, an indoor unit, and a control means,
When the control means is performing a refrigerant recovery operation for recovering the refrigerant of the air conditioner into a plurality of the refrigerant recovery units, the refrigerant recovery amount recovered by at least one of the refrigerant recovery units is the refrigerant recovery unit. The refrigerant recovery operation is interrupted, the refrigerant staying in at least one of the refrigerant recovery units is discharged from the refrigerant recovery unit, and then the refrigerant recovery is performed. An air conditioner characterized by restarting operation. An outdoor unit having a compressor, an outdoor heat exchanger, and an accumulator, and the indoor unit are air conditioners connected by a liquid refrigerant pipe and a gas refrigerant pipe,
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 refrigerant recovery bypass circuit having a refrigerant recovery on-off valve that bypasses between the refrigerant cutoff mechanism and between the gas refrigerant cutoff mechanism and the accumulator, and performs opening / closing control of each of the refrigerant cutoff mechanisms and all of the on-off valves. Control means, and
When the control means is performing a refrigerant recovery operation in which the refrigerant of the air conditioner is recovered in the outdoor unit, the operating state quantity that fluctuates in accordance with the fluctuation of the refrigerant amount staying in the outdoor heat exchanger is the first. The refrigerant amount staying in the outdoor heat exchanger is determined to be greater than or equal to the outdoor heat exchanger allowable refrigerant recovery amount that is the amount of refrigerant that can be recovered in the outdoor heat exchanger, and the gas refrigerant shut-off And closes the mechanism and the liquid refrigerant shut-off mechanism, interrupts the refrigerant recovery operation and executes a heat exchanger discharge operation for discharging the liquid refrigerant staying in the outdoor heat exchanger, and the operating state quantity is a first predetermined amount If it becomes equal to or less than a second predetermined threshold value that is smaller than the threshold value, it is determined that the refrigerant amount staying in the outdoor heat exchanger is equal to or less than the outdoor heat exchanger allowable refrigerant recovery amount, and the gas refrigerant cutoff mechanism or the liquid refrigerant cutoff is determined. Open the mechanism, the refrigerant recovery operation To resume,
The control means, when performing the refrigerant recovery operation, if the operating state variable that fluctuates according to the fluctuation of the refrigerant amount staying in the accumulator is equal to or less than a third predetermined threshold, the amount of refrigerant staying in the accumulator Is equal to or greater than the accumulator allowable refrigerant recovery amount that is the amount of refrigerant that can be recovered by the accumulator, the gas refrigerant shut-off mechanism and the liquid refrigerant shut-off mechanism are closed, and the refrigerant recovery operation is interrupted. The surplus refrigerant discharge operation for discharging the liquid refrigerant staying in the accumulator is executed, and if the operating state quantity is equal to or greater than a fourth predetermined threshold value smaller than a third predetermined threshold value, the refrigerant quantity staying in the accumulator is It is determined that the amount is less than the accumulator allowable refrigerant recovery amount, the gas refrigerant cutoff mechanism or the liquid refrigerant cutoff mechanism is opened, and the refrigerant recovery operation is resumed. That,
An air conditioner characterized by that. The outdoor unit has a refrigerant heating means for heating the liquid refrigerant staying in the accumulator,
The air conditioner according to claim 2, wherein the control means heats the liquid refrigerant staying in the accumulator by the refrigerant heating means when performing the surplus refrigerant discharge operation. The outdoor unit bypasses an outdoor on-off valve that adjusts a refrigerant flow rate in the outdoor heat exchanger, between the outdoor heat exchanger and the outdoor on-off valve, and between the gas refrigerant shut-off mechanism and the accumulator. A heat exchange refrigerant discharge bypass circuit having a heat exchange refrigerant discharge pipe and a heat exchange refrigerant discharge opening / closing valve provided in the heat exchange refrigerant discharge pipe and passing / blocking the heat exchange refrigerant discharge pipe;
The control means, when performing the heat exchanger discharge operation, opens the heat exchanger discharge on-off valve without opening the outdoor on-off valve,
The air conditioner according to claim 2.

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