JP2019143877A - Air conditioning system - Google Patents

Abstract

To provide an air conditioning device capable of properly executing a pump-down operation in occurrence of refrigerant leakage.SOLUTION: A CPU 210 sucks a suction pressure Ps when a first prescribed time tp1 has passed from start of a pump-down operation, and determines whether the sucked suction pressure Ps is a second threshold pressure Pst2 or less. When the sucked suction pressure Ps is the second threshold pressure Pst2 or less (ST14-Yes), the CPU 210 terminates the pump-down operation. On the other hand, when the sucked suction pressure Ps is not less than the second threshold pressure Pst2, the CPU 210 determined whether a second prescribed time tp2 has passed from the start of the pump-down operation is determined. When the second prescribed time tp2 has not passed, the CPU 210 continues the pump-down operation. When the second prescribed time tp2 has passed, the CPU 210 terminates the pump-down operation.SELECTED DRAWING: Figure 3

Description

  The present invention relates to an air conditioning system having an air conditioning apparatus and a refrigerant leakage detection means, and more particularly to an air conditioning apparatus capable of performing a pump-down operation in which refrigerant circulating through a refrigerant circuit of the air conditioning apparatus is collected in an outdoor unit.

  Conventionally, as an air conditioner having a refrigerant circuit formed by connecting an outdoor unit and an indoor unit with a liquid pipe and a gas pipe, when the indoor unit is moved, or when the outdoor unit or the indoor unit is replaced There has been proposed an apparatus capable of performing a pump-down operation in which the refrigerant sealed in the refrigerant circuit is collected in an accumulator or an outdoor heat exchanger of the outdoor unit.

  For example, Patent Document 1 discloses an outdoor unit in which a refrigerant circuit is in a cooling operation state, that is, a state in which an outdoor heat exchanger functions as a condenser, and a liquid pipe is connected when performing pump down operation. The air conditioner which collects the refrigerant | coolant in a refrigerant circuit in the accumulator of an outdoor unit or an outdoor heat exchanger by closing a closing valve of this and rotating a compressor is described. In this air conditioner, the suction pressure, which is the pressure of the refrigerant sucked into the compressor during the pump down operation, is detected, and the compressor is stopped when the detected suction pressure becomes lower than a predetermined value. At the same time, the shutoff valve of the outdoor unit to which the gas pipe is connected is closed, and the pump-down operation is terminated.

  By the way, if the air conditioner is a multi-room type air conditioner in which a plurality of indoor units are connected to one outdoor unit, the amount of refrigerant enclosed in the refrigerant circuit increases. In such a multi-chamber air conditioner, when the refrigerant leaks from the refrigerant circuit due to a crack in the refrigerant pipe constituting the refrigerant circuit, the enclosed refrigerant is a GWP (global warming) such as R410A. If the HFC refrigerant has a high coefficient), the influence of the leaked refrigerant on the environment is increased by being diffused into the atmosphere. Further, if the encapsulated refrigerant is an HFC refrigerant having a low GWP such as R32 but having flammability, the refrigerant may ignite depending on the refrigerant concentration in the room where the refrigerant leaks.

  As described above, when the refrigerant leaks from the refrigerant circuit, if the pump-down operation is performed in the same manner as when the air conditioner is moved or changed, the refrigerant existing in the refrigerant circuit is recovered by the outdoor unit. The amount of refrigerant leakage from the refrigerant circuit can be reduced.

JP-A-63-75445

  However, when the pump down operation is performed when the refrigerant leaks from the refrigerant circuit, there is a possibility that the problem described below may occur.

  The timing at which the pump-down operation is performed in response to the occurrence of the refrigerant leakage includes when the refrigerant is leaked when the air-conditioning apparatus is stopped and performing the pump-down operation, and when the air-conditioning apparatus is in operation. It is considered that the pump down operation is performed by detecting the leakage of the water. In any case, it is necessary to switch the refrigerant circuit to the state of the cooling operation as described above before performing the pump-down operation, but before the refrigerant circuit is switched to the state of the cooling operation, the refrigerant circuit The pressure difference between the high pressure side refrigerant pressure and the low pressure side refrigerant pressure in the circuit must be small. Since the pressure difference is originally small when the air conditioner is stopped, the refrigerant circuit can be immediately switched to the cooling operation state. On the other hand, when the air conditioner is in operation, it is necessary to perform a so-called pressure equalization process for reducing the pressure difference.

  As described above, when the pressure difference is reduced and the refrigerant circuit is switched to start the pump-down operation, immediately after starting the compressor, the refrigerant pipe connected to the compressor suction side is connected to the compressor suction side. The refrigerant that is sucked into the compressor temporarily decreases until the refrigerant that is present in the vicinity is sucked and then the refrigerant that is present in the indoor unit flows into the outdoor unit. In such a situation, immediately after starting the compressor, the refrigerant present at a location close to the suction side of the compressor is sucked in the suction pipe connected to the suction side of the compressor, and then the above-described pressure difference is increased. Until the refrigerant becomes larger and the refrigerant flows in the refrigerant circuit, the refrigerant flowing into the suction pipe temporarily decreases and the amount of refrigerant sucked into the compressor also decreases.

  When the amount of refrigerant sucked into the compressor 21 decreases, the suction pressure decreases. In particular, in a state where refrigerant leakage occurs, the suction pressure decreases quickly and greatly, and the above-described pump-down operation ends. There is a high possibility that the value will fall below a predetermined value for determining. Then, when the suction pressure decreases and falls below a predetermined value, the pump-down operation ends. That is, immediately after the pump-down operation is started, there is a possibility that the pump-down operation may be terminated due to a temporary decrease in the suction pressure due to the above-described factors.

  In addition, during the pump down operation, if the shutoff valve of the outdoor unit to which the liquid pipe is connected is not completely closed due to a failure or the entry of foreign matter, it will flow into the outdoor unit due to the pump down operation. Since the discharged refrigerant flows out of the outdoor unit through the outdoor unit closing valve to which the liquid pipe is connected, the refrigerant cannot be collected in the outdoor unit. Thus, when the refrigerant cannot be recovered in the outdoor unit in the pump down operation, the suction pressure does not become lower than the above-described predetermined value even if time elapses after the pump down operation is started. Down operation is performed for a long time without stopping. And there was a problem that the longer the pump-down operation was performed, the greater the amount of refrigerant leaking from the refrigerant circuit.

  In other words, when the pump down operation is performed when refrigerant leakage occurs from the refrigerant circuit, the refrigerant cannot be recovered to the outdoor unit as intended unless the judgment to end the pump down operation is made appropriately. In some cases, there is a problem that the amount of refrigerant leaking from the refrigerant circuit increases.

  The present invention solves the above-described problems, and an object thereof is to provide an air conditioning system that can appropriately perform a pump-down operation when refrigerant leakage occurs.

  In order to solve the above problems, the air conditioning system of the present invention includes an air conditioning apparatus and a refrigerant leakage detection means. An air conditioner includes an outdoor unit having a compressor, an outdoor heat exchanger, a four-way valve, and suction pressure detecting means for detecting a suction pressure of the compressor, an indoor unit having an indoor heat exchanger, an outdoor unit, and an indoor unit Are connected by a liquid pipe and a gas pipe, and a refrigerant circuit in which a refrigerant is sealed is included, and a control unit that performs drive control of the compressor. The outdoor unit is connected to the liquid pipe and is connected to the liquid pipe to block the refrigerant flow between the outdoor unit and the liquid pipe. The outdoor unit is connected to the gas pipe and the refrigerant flows between the outdoor unit and the gas pipe. And a gas side shut-off valve capable of shutting off. The refrigerant leakage detection means detects refrigerant leakage from the refrigerant circuit and notifies the control means. When the control means receives a notification from the refrigerant leakage detection means that the refrigerant leakage has been detected in the refrigerant circuit, the outdoor heat exchanger functions as a condenser and the indoor heat exchanger functions as an evaporator. And the pump down operation which collect | recovers the refrigerant | coolant enclosed with the refrigerant circuit to an outdoor unit is started by closing a liquid side closing valve and opening a gas side closing valve, and driving a compressor. If the suction pressure detected by the suction pressure detection means is less than a predetermined threshold pressure after a predetermined first predetermined time has elapsed from the time when the pump down operation is started, the control means performs the pump down operation. If the suction pressure does not become smaller than the predetermined threshold pressure even after a predetermined second predetermined time longer than the first predetermined time from the time when the pump down operation is started, the detected suction pressure is set. Regardless, the pump down operation ends.

  The air conditioning system of the present invention configured as described above is a pump that uses the detected suction pressure until the first predetermined time elapses from the start of the pump-down operation in the pump-down operation when refrigerant leakage occurs. If the second predetermined time longer than the first predetermined time has elapsed from the start of the pump down operation, the pump down operation is ended regardless of the detected suction pressure. Thereby, the pump down operation at the time of refrigerant leakage can be performed appropriately.

It is explanatory drawing of the air conditioning apparatus in embodiment of this invention, (A) is a refrigerant circuit figure, (B) is a block diagram of an outdoor unit control means. It is a refrigerant circuit figure at the time of the air conditioning apparatus of this invention performing a pump down driving | operation. It is a flowchart which shows the process at the time of performing the control regarding pump down driving | operation in embodiment of this invention.

  Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. As an embodiment, 10 indoor units are connected in parallel to one outdoor unit, and an air conditioner that can perform a cooling operation or a heating operation simultaneously in all the indoor units and a refrigerant leaking from the air conditioner are detected. An air conditioning system having a refrigerant leakage detection means that performs this 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.

  As shown in FIG. 1A, an air conditioner 1 of an air conditioning system according to this embodiment includes one outdoor unit 2 and 10 connected to the outdoor unit 2 in parallel by a liquid pipe 8 and a gas pipe 9. The indoor unit 5 (only two of them are drawn in FIG. 1A) and the refrigerant leakage detection means 100 disposed in the room where the ten indoor units 5 are installed. I have. The liquid side closing valve 25 of the outdoor unit 2 and the liquid pipe connection part 53 of each indoor unit 5 are connected by the liquid pipe 8. Further, the gas side closing valve 26 of the outdoor unit 2 and the gas pipe connection portion 54 of each indoor unit 5 are connected by the gas pipe 9. Thus, the one outdoor unit 2 and the ten indoor units 5 are connected by the liquid pipe 8 and the gas pipe 9, and the refrigerant circuit 10 of the air conditioning apparatus 1 is formed.

<Configuration of outdoor unit>
First, the outdoor unit 2 will be described. The outdoor unit 2 includes a compressor 21, a four-way valve 22, an outdoor heat exchanger 23, an outdoor expansion valve 24, a liquid side closing valve 25 to which the liquid pipe 8 is connected, and a gas to which the gas pipe 9 is connected. A side closing valve 26, an accumulator 27, an outdoor fan 28, and an outdoor unit control means 200 are provided. Then, these devices other than the outdoor fan 28 and the outdoor unit control means 200 are connected to each other through refrigerant pipes described in detail below to form an outdoor unit refrigerant circuit 20 that forms a part of the refrigerant circuit 10. Yes.

  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 refrigerant discharge side of the compressor 21 is connected to a port a of a four-way valve 22 to be described later and a discharge pipe 41, and the refrigerant suction side of the compressor 21 is connected to the refrigerant outflow side of the accumulator 27 and a suction pipe 42. Has been. Refrigerating machine oil that is supplied to a compression mechanism unit (not shown) disposed above the closed container of the compressor 21 and maintains the lubricity of the compression mechanism unit is stored in the lower part of the sealed container of the compressor 21.

  The four-way valve 22 is a valve for switching the flow direction of the refrigerant in the refrigerant circuit 10 and includes four ports a, b, c, and d. The port a is connected to the refrigerant discharge side of the compressor 21 by the discharge pipe 41 as described above. The port b is connected to one refrigerant inlet / outlet of the outdoor heat exchanger 23 by a refrigerant pipe 43. The port c is connected to the refrigerant inflow side of the accumulator 27 by a refrigerant pipe 46. The port d is connected to the gas side shutoff valve 26 by an outdoor unit gas pipe 45.

  The outdoor heat exchanger 23 exchanges heat between the refrigerant and the outside air taken into the outdoor unit 2 by the rotation of the outdoor fan 28 described later. One refrigerant inlet / outlet of the outdoor heat exchanger 23 and the port b of the four-way valve 22 are connected by a refrigerant pipe 43. In addition, the other refrigerant inlet / outlet of the outdoor heat exchanger 23 and the liquid side closing valve 25 are connected by an outdoor unit liquid pipe 44. The outdoor heat exchanger 23 functions as a condenser when the air conditioner 1 performs a cooling operation, and functions as an evaporator when the air conditioner 1 performs a heating operation.

  The outdoor expansion valve 24 is provided in the outdoor unit liquid pipe 44. The outdoor expansion valve 24 is an electronic expansion valve driven by a pulse motor (not shown), and the amount of refrigerant flowing into the outdoor heat exchanger 23 or the outdoor volume is adjusted by adjusting the opening degree according to the number of pulses applied to the pulse motor. The amount of refrigerant flowing out of the heat exchanger 23 is adjusted. The opening degree of the outdoor expansion valve 24 is adjusted according to the discharge temperature of the compressor 21 detected by a discharge temperature sensor 33 (described later) when the air-conditioning apparatus 1 is performing a heating operation. When the operation is performed, the opening is fully opened.

  Each of the liquid side closing valve 25 and the gas side closing valve 26 is an electric ball valve. An outdoor unit liquid pipe 44 is connected to one refrigerant inlet / outlet of the liquid side closing valve 25, and a liquid pipe 8 is connected to the other refrigerant inlet / outlet. An outdoor unit gas pipe 45 is connected to one refrigerant inlet / outlet of the gas side shut-off valve 26, and a gas pipe 9 is connected to the other refrigerant inlet / outlet. The liquid side shut-off valve 25 and the gas side shut-off valve 26 are always opened regardless of whether the air-conditioning operation is being stopped or stopped, except when a pump-down operation to be described later is performed.

  The accumulator 27 has a refrigerant inflow side connected to the port c of the four-way valve 22 and a refrigerant pipe 46, and a refrigerant outflow side connected to the refrigerant suction side of the compressor 21 through a suction pipe 42. The accumulator 27 separates the refrigerant flowing into the accumulator 28 from the refrigerant pipe 46 into a gas refrigerant and a liquid refrigerant, and causes the compressor 21 to suck only the gas refrigerant.

  The outdoor fan 28 is formed of a resin material and is disposed in the vicinity of the outdoor heat exchanger 23. The outdoor fan 28 is rotated by a fan motor (not shown) to take outside air into the interior of the outdoor unit 2 from a suction port (not shown), and the outdoor air heat exchanged with the refrigerant in the outdoor heat exchanger 23 is sent from an outlet (not shown) to the outdoor unit. 2 to the outside.

  In addition to the configuration described above, the outdoor unit 2 is provided with various sensors. As shown in FIG. 1, a discharge pressure sensor 31 that detects a discharge pressure that is a pressure of refrigerant discharged from the compressor 21 and a discharge that detects the temperature of refrigerant discharged from the compressor 21 are disposed in the discharge pipe 41. A temperature sensor 33 is provided. Near the refrigerant inlet of the accumulator 28 in the refrigerant pipe 46, a suction pressure sensor 32 that detects a suction pressure that is a pressure of the refrigerant sucked into the compressor 21, and a temperature of the refrigerant sucked into the compressor 21 are detected. A suction temperature sensor 34 is provided. The suction pressure sensor 32 is the suction pressure detection means of the present invention.

  Between the outdoor heat exchanger 23 and the outdoor expansion valve 24 in the outdoor unit liquid pipe 44, the temperature of the refrigerant flowing into the outdoor heat exchanger 23 or the temperature of the refrigerant flowing out of the outdoor heat exchanger 23 is detected. A heat exchanger temperature sensor 35 is provided. An outdoor air temperature sensor 36 that detects the temperature of the outside air that flows into the outdoor unit 2, that is, the outside air temperature, is provided near the suction port (not shown) of the outdoor unit 2.

  Further, the outdoor unit 2 is provided with an outdoor unit control means 200 which is a control means of the present invention. The outdoor unit control means 200 is mounted on a control board stored in an electrical component box (not shown) of the outdoor unit 2, and as shown in FIG. 1B, a CPU 210, a storage unit 220, a communication unit 230, The sensor input unit 240 is provided.

  The storage unit 220 includes, for example, a flash memory. The storage unit 220 transmits a detection value corresponding to a control program of the outdoor unit 2 and detection signals from various sensors, driving states of the compressor 21 and the outdoor fan 28, and transmission from each indoor unit 5. The operation information (including operation / stop information, operation mode such as cooling / heating) is stored. The communication unit 230 is an interface that performs communication with each indoor unit 5. The sensor input unit 240 takes in the detection results of various sensors of the outdoor unit 2 and the detection results of the refrigerant leakage detection means 100 described later and outputs them to the CPU 210.

  CPU210 takes in the detection result in the various sensors of the outdoor unit 2, and the refrigerant | coolant leakage detection means 100 via the sensor input part 240 regularly (for example, every 30 seconds). In addition, a signal including operation information transmitted from each indoor unit 5 is input to the CPU 210 via the communication unit 230. The CPU 210 adjusts the opening degree of the outdoor expansion valve 24 and controls the drive of the compressor 21 and the outdoor fan 28 based on various information that has been taken in or input.

<Configuration of each indoor unit>
Next, the ten indoor units 5 will be described. The ten indoor units 5 are all installed in the same room and have the same configuration. The indoor heat exchanger 51, the indoor expansion valve 52, the liquid pipe connection part 53, and the gas pipe connection part 54 And an indoor fan 55. These constituent devices other than the indoor fan 55 are connected to each other through refrigerant pipes described in detail below to constitute an indoor unit refrigerant circuit 50 that forms part of the refrigerant circuit 10.

  The indoor heat exchanger 51 exchanges heat between the refrigerant and the indoor air taken into the indoor unit 5 from a suction port (not shown) by rotation of an indoor fan 55 described later. One refrigerant inlet / outlet of the indoor heat exchanger 51 and the liquid pipe connecting portion 53 are connected by an indoor unit liquid pipe 71, and the other refrigerant inlet / outlet and the gas pipe connecting portion 54 a are connected by an indoor unit gas pipe 72. The indoor heat exchanger 51 functions as an evaporator when the air conditioner 1 performs a cooling operation, and functions as a condenser when the air conditioner 1 performs a heating operation. Note that the refrigerant pipes of the liquid pipe connection part 53 and the gas pipe connection part 54 are connected by welding, flare nuts, or the like.

  The indoor expansion valve 52 is provided in the indoor unit liquid pipe 71. The indoor expansion valve 52 is an electronic expansion valve, and when the indoor heat exchanger 51 functions as an evaporator, that is, when the indoor unit 5 performs a cooling operation, the opening degree of the indoor expansion valve 52 depends on the refrigerant outlet (gas The refrigerant superheat degree at the pipe connecting portion 54 side) is adjusted so as to become the target refrigerant superheat degree. Further, when the indoor heat exchanger 51 functions as a condenser, that is, when the indoor unit 5 performs the heating operation, the opening of the indoor expansion valve 52 is the refrigerant outlet (liquid pipe connection portion) of the indoor heat exchanger 51. (53 side) is adjusted so that the refrigerant subcooling degree becomes the target refrigerant subcooling degree. Here, the target refrigerant superheat degree and the target refrigerant subcool degree are the refrigerant superheat degree and the refrigerant subcool degree necessary for the indoor unit 5 to exhibit sufficient cooling capacity or heating capacity.

  The indoor fan 55 is formed of a resin material and is disposed in the vicinity of the indoor heat exchanger 51. The indoor fan 55 is rotated by a fan motor (not shown) to take indoor air from the suction port (not shown) into the indoor unit 5, and the indoor air exchanged with the refrigerant in the indoor heat exchanger 51 from the blower outlet (not shown). Release into the room.

  In addition to the configuration described above, the indoor unit 5 is provided with various sensors. Between the indoor heat exchanger 51 and the indoor expansion valve 52 in the indoor unit liquid pipe 71, there is a liquid side temperature sensor 61 that detects the temperature of the refrigerant flowing into or out of the indoor heat exchanger 51. Is provided. The indoor unit gas pipe 72 is provided with a gas side temperature sensor 62 that detects the temperature of the refrigerant flowing out of the indoor heat exchanger 51 or flowing into the indoor heat exchanger 51. A suction temperature sensor 63 that detects the temperature of indoor air flowing into the indoor unit 5, that is, the suction temperature, is provided near the suction port (not shown) of the indoor unit 5.

<Refrigerant leak detection means>
The refrigerant leakage detection means 100 of the air conditioning system in the present embodiment is arranged in a room in which ten indoor units 5 are installed, and any of the indoor unit refrigerant circuit 50, the liquid pipe 8, and the gas pipe 9 in the refrigerant circuit 10. Detects refrigerant leaking from the room. The refrigerant leakage detection means 100 is, for example, a semiconductor sensor, and detects a change in resistance value that occurs when the metal oxide semiconductor heated by the heater comes into contact with the refrigerant as the refrigerant concentration. In addition, what is necessary is just to arrange | position the refrigerant | coolant leak detection means 100 in each room, when the ten indoor units 5 are divided and installed in several rooms. Further, the refrigerant leakage detection means 100 may be disposed inside each indoor unit 5, or may be disposed in both the interior of each indoor unit 5 and the room in which each indoor unit 5 is installed.

<Operation of refrigerant circuit>
Next, the flow of the refrigerant and the operation of each part in the refrigerant circuit 10 during the air conditioning operation of the air-conditioning apparatus 1 in the present embodiment will be described with reference to FIG. In addition, in the following description, the case where the air conditioning apparatus 1 performs a cooling operation will be described, and the detailed description of the case where a heating operation is performed will be omitted. Moreover, the arrow in FIG. 1 has shown the flow of the refrigerant | coolant at the time of air_conditionaing | cooling operation.

  As shown in FIG. 1, when the air-conditioning apparatus 1 performs a cooling operation, the four-way valve 22 is in a state indicated by a solid line, that is, the port a and the port b of the four-way valve 22 communicate with each other, and the port c And the port d are switched to communicate with each other. Thereby, the refrigerant circuit 10 becomes a cooling cycle in which each indoor heat exchanger 51 functions as an evaporator and the outdoor heat exchanger 23 functions as a condenser.

  When the compressor 21 is driven in the state of the refrigerant circuit 10 as described above, the refrigerant discharged from the compressor 21 flows through the discharge pipe 41 and flows into the four-way valve 22, and from the four-way valve 22 through the refrigerant pipe 43. It flows into the outdoor heat exchanger 23.

  The refrigerant flowing into the outdoor heat exchanger 23 is condensed by exchanging heat with the outside air taken into the outdoor unit 2 by the rotation of the outdoor fan 28. The refrigerant that has flowed out of the outdoor heat exchanger 23 into the outdoor unit liquid pipe 44 passes through the outdoor expansion valve 24 whose opening is fully opened, and flows out into the liquid pipe 8 through the liquid side closing valve 25.

  The refrigerant flowing through the liquid pipe 8 is divided into each indoor unit 5 through the liquid pipe connection portion 53. The refrigerant that has flowed into each indoor unit 5 flows through each indoor unit liquid pipe 71, and each indoor unit whose opening degree is adjusted so that the refrigerant superheat degree at each refrigerant outlet of the indoor heat exchanger 51 becomes the target refrigerant superheat degree. When passing through the expansion valve 52, the pressure is reduced.

  The refrigerant flowing into each indoor heat exchanger 51 from each indoor unit liquid pipe 71 evaporates by exchanging heat with the indoor air taken into each indoor unit 5 by the rotation of each indoor fan 55. Thus, each indoor heat exchanger 51 functions as an evaporator, and the indoor air cooled by performing heat exchange with the refrigerant in each indoor heat exchanger 51 is blown into the room from a blower outlet (not shown). Cooling of the room in which ten indoor units 5 are installed is performed.

  The refrigerant that has flowed out from each indoor heat exchanger 51 to each indoor unit gas pipe 72 flows out to the gas pipe 9 via each gas pipe connecting portion 54. The refrigerant that merges in the gas pipe 9 and flows into the outdoor unit 2 through the liquid-side closing valve 25 flows in the order of the outdoor unit gas pipe 45, the four-way valve 22, the refrigerant pipe 46, the accumulator 27, and the suction pipe 42. Inhaled and compressed again.

  When the air conditioner 1 performs the heating operation, the four-way valve 22 is in a state indicated by a broken line, that is, the port a and the port d of the four-way valve 22 communicate with each other, and the port b and the port c communicate with each other. Can be switched. Thereby, the refrigerant circuit 10 becomes a heating cycle in which each indoor heat exchanger 51 functions as a condenser and the outdoor heat exchanger 23 functions as an evaporator.

<About pump down operation when refrigerant leakage occurs>
Next, the pump-down operation performed when the refrigerant leaks from the refrigerant circuit 10 in the air-conditioning apparatus 1 of the present embodiment will be described with reference to FIGS. 2 and 3. In the following description, as shown in FIG. 2, a crack occurs between the indoor expansion valve 52 and the liquid pipe connection portion 53 in the indoor unit liquid pipe 71 of one indoor unit 5, and 10 units are formed from this crack. The case where the refrigerant leakage detection means 100 detects that the refrigerant has leaked into the room in which the indoor unit 5 is installed will be described as an example.

  FIG. 2 shows the state of the refrigerant circuit 10 when the air conditioner 1 performs the pump-down operation. In FIG. 2, the broken line arrows indicate the flow of the refrigerant during the pump-down operation, and among the various valves, the open valve is indicated by white and the closed valve is indicated by black.

  FIG. 3 is a flowchart showing processing performed by the CPU 210 of the outdoor unit control unit 200 when the refrigerant leakage detection unit 100 detects refrigerant leakage and performs a pump-down operation in the air conditioner 1. In FIG. 3, ST represents a process step, and the number following this represents a step number. In FIG. 3, the pressure equalizing time is tu, the first predetermined time is tp1, the second predetermined time is tp2, the suction pressure is Ps, the first threshold pressure is Pst1, and the second threshold pressure is Pst2. Each time and each pressure will be described in detail in the following description of FIG. In FIG. 3, only the process related to the present invention is mentioned, and the process related to the general control of the air conditioner 1 such as the control of the compressor 21 according to the air conditioning capability requested by the user. Description and description are omitted.

  When the air conditioner 1 is performing a cooling operation or a heating operation (hereinafter sometimes referred to as an air conditioning operation) or when the air conditioner 1 is stopped, the CPU 210 It is determined whether or not refrigerant leakage is detected in the room where the machine 5 is installed (ST1). Specifically, the CPU 210 periodically detects the refrigerant concentration in the room where the ten indoor units 5 are installed, detected by the refrigerant leakage detection unit 100 via the sensor input unit 240 via the sensor input unit 240 ( For example, if the concentration of the refrigerant that has been taken in increases every 30 seconds), it is determined that refrigerant leakage has occurred in a room in which ten indoor units 5 are installed.

  When the refrigerant leakage is not detected (ST1-No), the CPU 210 maintains the current state (ST17) and returns the process to ST1. Here, maintaining the current state means that if the air conditioner 1 is performing the air conditioning operation, it means that the air conditioner operation currently being performed is continued, and the air conditioner 1 stops the operation. Means that the operation is stopped.

  When the refrigerant leakage is detected (ST1-Yes), the CPU 210 determines whether the air-conditioning operation is currently performed (ST2). If the air-conditioning operation is not currently performed (ST2-No), the CPU 210 advances the process to ST4. If the air-conditioning operation is currently being performed (ST2-No), the CPU 210 performs an operation stop process (ST3) and proceeds to ST4. In the operation stop process, the CPU 210 stops the compressor 21 and the outdoor fan 28 and instructs each indoor unit 5 to stop the indoor fan 51 via the communication unit 230.

  CPU210 which completed the process of ST2 or ST3 performs a pump down start process (ST4). Specifically, the CPU 210 brings the port a and the port b of the four-way valve 22 into communication and the port c and the port d into communication, that is, sets the four-way valve 22 to the same state as in the cooling cycle. Further, the CPU 210 fully opens the opening of the outdoor expansion valve 24 and closes the liquid side closing valve 25. In addition, the CPU 210 instructs each indoor unit 5 to fully open the opening of the indoor expansion valve 52 via the communication unit 230. As described above, each valve is operated in the pump-down start process, and the refrigerant circuit 10 enters the state shown in FIG. In the pump down start process, when the four-way valve 22 is already in the above state, that is, when the air conditioner 1 is performing a cooling operation or when the operation before stopping is a cooling operation. The operation of the four-way valve 22 in the pump down start process is not necessary. Further, as described above, the gas side closing valve 26 is always opened regardless of whether the air conditioning operation is being performed or stopped. Therefore, the gas side closing valve 26 is not operated in the pump down start process.

  Next, the CPU 210 starts timer measurement (ST5). The CPU 210 has a timer measurement function (not shown).

  Next, the CPU 210 determines whether or not the pressure equalizing time tu has elapsed after starting the timer measurement in ST5 (ST6). Here, the pressure equalization time tu is obtained by performing a test or the like in advance and stored in the storage unit 220, and the refrigerant circuit 10 equalizes the pressure when the refrigerant circuit 10 is in the state shown in FIG. That is, the pressure of the high-pressure side refrigerant in the refrigerant circuit 10 (for example, the discharge pressure detected by the discharge pressure sensor 31) and the pressure of the low-pressure side refrigerant in the refrigerant circuit 10 (for example, the suction pressure Ps detected by the suction pressure sensor 32). Is a time required for the pressure difference to become a predetermined value (for example, 0.2 MPa) or less. As an example, the pressure equalizing time tu is 180 seconds.

  If the pressure equalization time tu has not elapsed (ST6-No), the CPU 210 returns to ST6 and waits for the pressure equalization time tu to elapse. If the pressure equalizing time tu has elapsed (ST6-Yes), the CPU 210 advances the process to ST7.

  The processes from ST3 to ST6 described above are processes related to the pressure equalization of the refrigerant circuit 10. The liquid side closing valve 25 is closed in the pump down operation start process of ST4. The liquid side closing valve 25 is equalized in the refrigerant circuit 10 regardless of whether it is closed or opened when the refrigerant circuit 10 is equalized. Has no direct effect. However, when the liquid side closing valve 25 is an electric ball valve that takes time to open and close as in the air conditioner 1 of the present embodiment, the liquid side closing valve 25 is closed when the refrigerant circuit 10 is equalized. If so, the pump-down operation can be started immediately because the liquid side shut-off valve 25 is already closed when the CPU 210 performs the process of ST10 described later. When the liquid side closing valve 25 is a valve that can be opened and closed in a short time, the liquid side closing valve 25 may be closed when performing the process of ST10.

  CPU210 which completed the process of ST6 resets a timer (ST7), and takes in the suction pressure Ps (ST8). Specifically, the CPU 210 takes in the suction pressure Ps detected by the suction pressure sensor 32 via the sensor input unit 240.

  Next, the CPU 210 determines whether or not the suction pressure Ps captured in ST8 is equal to or lower than the first threshold pressure Pst1 (ST9). Here, the first threshold pressure Pst1 is obtained by performing a test or the like in advance and stored in the storage unit 220. As an example, the first threshold pressure Pst1 is 0.24 MPa. The first threshold pressure Pst1 is provided for the reason described below.

  The suction pressure Ps detected after pressure equalization in the refrigerant circuit 10 after detection of the refrigerant leakage is smaller than the suction pressure Ps after pressure equalization when no refrigerant leakage occurs, and the suction pressure Ps is a small value. The more the amount of refrigerant leaked from the refrigerant circuit 10, the greater the amount. When the refrigerant leakage amount during pressure equalization increases, the temperature inside the compressor 21 rises due to the small amount of refrigerant sucked into the compressor 21 in the pump-down operation after pressure equalization. There is a possibility that the compression mechanism portion 21 is seized. Further, when the amount of refrigerant leakage from the refrigerant circuit 10 increases, the amount of air flowing into the refrigerant circuit 10 from the location where the refrigerant leakage occurs in the refrigerant circuit 10 during the pump down operation also increases. At this time, a large amount of air sucked into the compressor 21 in the pump-down operation after pressure equalization is mixed with the refrigerating machine oil that has risen to the ignition temperature in accordance with the temperature rise inside the compressor 21, so that the refrigerating machine oil spontaneously ignites. Then, the compressor 21 may burst.

  Therefore, in the air conditioner 1 of the present embodiment, the amount of refrigerant leaking from the refrigerant circuit 10 causes the above-described seizure of the compression mechanism portion of the compressor 21 or rupture of the compressor 21 when the pump-down operation is performed. The first threshold pressure Pst1 is set as an index for determining whether or not the leakage amount is unlikely to occur. That is, if the suction pressure Ps detected after pressure equalization in the refrigerant circuit 10 is equal to or lower than the first threshold pressure Pst1, the amount of refrigerant leakage from the refrigerant circuit 10 is large, and the compression mechanism portion of the compressor 21 is seized or the compressor 21 Indicates that rupture is likely to occur. Further, if the suction pressure Ps detected after the pressure equalization in the refrigerant circuit 10 exceeds the first threshold pressure Pst1, the refrigerant leakage amount from the refrigerant circuit 10 is small, and the compression mechanism portion of the compressor 21 is seized or the compressor 21 Indicates that rupture is unlikely to occur.

  In the process of ST9, if the suction pressure Ps is not equal to or higher than the first threshold pressure Pst (ST9-No), the CPU 210 advances the process to ST16 without performing the pump-down operation. If the suction pressure Ps is equal to or lower than the first threshold pressure Pst1 (ST9-Yes), the CPU 210 starts pump down operation (ST10) and starts timer measurement (ST11). In the pump down operation, the CPU 210 drives the compressor 21 at a predetermined rotational speed and drives the outdoor fan 28 at the maximum rotational speed. In addition, the CPU 210 instructs each indoor unit 5 to drive the indoor fan 51 at the maximum rotational speed via the communication unit 230.

  When the compressor 21 is driven, the refrigerant present on the indoor unit 5 side from the closed liquid side shut-off valve 25, that is, the refrigerant present in the liquid pipe 8, each indoor unit 5, and the gas pipe 9 is shown in FIG. As indicated by the broken line arrows, the refrigerant flows through the refrigerant circuit 10 and flows into the outdoor unit 2. The refrigerant that has flowed into the outdoor unit 2 does not flow out of the outdoor unit 2 again because the liquid-side closing valve 25 is closed, and is stored in the accumulator 27 and the outdoor heat exchanger 23.

  As described above, the predetermined number of rotations of the compressor 21 during the pump-down operation is obtained by performing a test or the like in advance and stored in the storage unit 220, and is 50 rps as an example. In the pump-down operation, it is desirable to quickly collect the refrigerant in the outdoor unit 2 by increasing the rotation speed of the compressor 21. On the other hand, as described above, during the pump-down operation, the temperature inside the compressor 21 is likely to rise due to the small amount of refrigerant sucked. In consideration of the above, the predetermined rotation speed of the compressor 21 during the pump-down operation of the present embodiment is the rotation speed at which the refrigerant can be recovered in the outdoor unit 2 as soon as possible while suppressing the temperature rise inside the compressor 21. It is said.

  Further, in the pump down operation, by driving the outdoor fan 28 at the maximum rotational speed, the condensation capacity of the outdoor heat exchanger 23 is increased, and most of the refrigerant flowing into the outdoor heat exchanger 23 is converted into liquid refrigerant. Compared to the case where the gas refrigerant is retained in the outdoor heat exchanger 23, a large amount of refrigerant can be stored in the outdoor heat exchanger 23. Further, in the pump-down operation, by driving each indoor fan 51 at the maximum rotation speed, the evaporation capacity of each indoor heat exchanger 51 is increased and most of the refrigerant flowing into each indoor heat exchanger 51 is used as a gas refrigerant. Since each indoor heat exchanger 51 is caused to flow out to the outdoor unit 2, the refrigerant present on the indoor unit 5 side can be collected in the outdoor unit 2 more quickly and reliably than when the liquid refrigerant is flowed to the outdoor unit 2.

  Next, CPU 210 determines whether or not first predetermined time tp1 has elapsed since the start of timer measurement in ST11 (ST12). If the first predetermined time tp1 has not elapsed (ST12-No), the CPU 210 returns to ST12 and waits for the first predetermined time tp1 to elapse.

  If the first predetermined time tp1 has elapsed (ST12-Yes), the CPU 210 takes in the suction pressure Ps by the same method as ST8 (ST13), and is the taken-in suction pressure Ps less than or equal to the second threshold pressure Pst2? It is determined whether or not (ST14).

  If the taken-in suction pressure Ps is equal to or lower than the second threshold pressure Pst2 (ST14-Yes), the CPU 210 advances the process to ST15. If the taken-in suction pressure Ps is not less than or equal to the second threshold pressure Pst2 (ST14-No), the CPU 210 determines whether or not the second predetermined time tp2 has elapsed since the start of the timer measurement in ST11 (ST18). .

  If the second predetermined time tp2 has not elapsed (ST18-No), the CPU 210 returns the process to ST14 and continues the pump-down operation. If second predetermined time tp2 has elapsed (ST18-Yes), CPU 210 advances the process to ST15.

  CPU210 which completed the process of ST9 or ST14 or ST18 performs a pump down driving | operation completion process (ST15). Specifically, the CPU 210 stops the compressor 21 and the outdoor fan 28 and closes the gas-side closing valve 26 when performing the pump-down operation end processing after finishing the processing of ST14 or ST18. In addition, the CPU 210 instructs each indoor unit 5 to stop the indoor fan 51 via the communication unit 230. On the other hand, when performing the pump-down operation end process when the suction pressure Ps is not equal to or higher than the first threshold pressure Pst1 in ST9 (ST9-No), the CPU 210 performs only the operation of closing the gas-side shutoff valve 26.

  Here, the second threshold pressure Pst2, the first predetermined time tp1, and the second predetermined time tp2 in the processes of ST12 to ST15 and ST18 described above are provided for the reasons described below. is there.

  First, the second threshold pressure Pst2 will be described. The second threshold pressure Pst2 is a predetermined threshold pressure according to the present invention, and is obtained in advance through a test or the like and stored in the storage unit 220. The second threshold pressure Pst2 is a pressure smaller than the first threshold pressure Pst1 described above. As an example, the second threshold pressure Pst2 is 0.2 MPa.

  When the pump down operation is started and the recovery of the refrigerant existing in the refrigerant circuit 10 to the outdoor unit 2 proceeds, the amount of refrigerant sucked by the compressor 21 decreases as time passes after the pump down operation is started. As a result, the suction pressure Ps decreases. On the other hand, the compressor 21 has a pressure lower limit value inherent in performance, and the compressor 21 cannot be continuously driven in a state where the suction pressure Ps is lower than the pressure lower limit value. The second threshold pressure Pst2 is set to a value (for example, 0.03 MPa) higher than this pressure lower limit value. If the suction pressure Ps becomes equal to or lower than the second threshold pressure Pst2 during the pump-down operation, the compressor 21 is set. Is stopped and the pump-down operation is ended, so that the compressor 21 is prevented from continuing to be driven in a state below the pressure lower limit value.

  Next, the first predetermined time tp1 will be described. The first predetermined time tp1 is obtained by performing a test or the like in advance and stored in the storage unit 220. As an example, the first predetermined time tp1 is 80 seconds.

  Immediately after the pump-down operation is started, that is, immediately after the compressor 21 is started, the high-pressure side refrigerant pressure and the low-pressure-side refrigerant pressure in the refrigerant circuit 10 are obtained by pressure equalization performed before the pump-down operation is performed. The pressure difference is small. This pressure difference does not increase until a while after the compressor 21 is started, and the refrigerant does not flow through the refrigerant circuit 10 unless the pressure difference increases. In such a situation, immediately after the compressor 21 is started, the refrigerant existing in the suction pipe 42 at a location near the suction side of the compressor 21 is sucked, and thereafter, the pressure difference becomes large and the refrigerant circuit 10 is filled. Until the refrigerant flows, the refrigerant flowing into the suction pipe 42 temporarily decreases and the amount of refrigerant sucked into the compressor 21 also decreases.

  When the amount of refrigerant sucked into the compressor 21 decreases, the suction pressure Ps may decrease and fall below the second threshold pressure Pst2. As described above, when the suction pressure Ps decreases and falls below the second threshold pressure Pst2, the CPU 210 stops the pump-down operation. However, as described above, the refrigerant sucked into the compressor 21 is decreased and the suction pressure Ps is temporarily reduced. If time passes after the pump-down operation is started, the pressure difference in the refrigerant circuit 10 is decreased. Since the refrigerant increases and the refrigerant present on the indoor unit 5 side from the accumulator 27 flows into the suction pipe 42 and is sucked into the compressor 21, the suction pressure Ps increases.

  The first predetermined time tp1 is the pressure of the refrigerant circuit 10 at which the refrigerant staying on the indoor unit 5 side from the accumulator 27 after the pump down operation starts flows into the suction pipe 42 and is sucked into the compressor 21. This is the time taken until the difference occurs, and is set to prevent the pump-down operation from being stopped due to the temporary decrease in the suction pressure Ps due to the above-described factors.

  Next, the second predetermined time tp2 will be described. The second predetermined time tp2 is obtained by conducting a test or the like in advance and stored in the storage unit 220. The second predetermined time tp2 is longer than the first predetermined time tp1 described above, and as an example, the second predetermined time tp2 is 600 seconds.

  As described above, the pump-down operation is stopped when the suction pressure Ps becomes equal to or lower than the second threshold pressure Pst2. However, if some trouble occurs and the refrigerant is not recovered in the outdoor unit 2 even if the pump-down operation is performed, for example, the liquid-side shut-off valve 25 is not completely closed due to a failure or a foreign object biting. When the pump down operation is performed, the refrigerant that has flowed into the outdoor unit 2 flows out of the outdoor unit 2 through the liquid-side closing valve 25 and circulates through the refrigerant circuit 10 again.

  As described above, when the refrigerant cannot be recovered in the outdoor unit 2 in the pump down operation, the suction pressure Ps does not become the second threshold pressure Pst2 or less even if time elapses after the pump down operation is started. Pump down operation is performed for a long time without stopping. The longer the pump-down operation is performed, the greater the amount of refrigerant that leaks from the refrigerant circuit 10.

  If there is no abnormality in the refrigerant circuit 10 of the air conditioner 1 during the second predetermined time tp2 in view of the amount of refrigerant enclosed in the refrigerant circuit 10, the ambient environment of the air conditioner 1 when performing the pump-down operation, and the like. If the pump-down operation is performed for the second predetermined time tp2, the time is set so that almost all of the refrigerant can be collected in the outdoor unit 2, and the pump-down operation is performed in a state where the refrigerant circuit 10 of the air conditioner 1 is abnormal. Is set to prevent the amount of refrigerant leaking from the refrigerant circuit 10 from increasing.

  CPU210 which completed the process of ST15 resets a timer (ST16), and complete | finishes the process in connection with a pump down driving | operation.

  In the embodiment described above, the case where the refrigerant concentration detected by the refrigerant leakage detection unit 100 is directly taken into the CPU 210 of the outdoor unit 2 via the sensor input unit 240 has been described. However, the present invention is not limited to this, and the refrigerant concentration detected by the refrigerant leakage detection unit 100 may be first taken into the indoor unit 5 and taken in by the CPU 210 from the indoor unit 5 via the communication unit 230.

  As described above, in the air conditioner 1 of the present embodiment, when refrigerant leakage from the refrigerant circuit 10 is detected, the refrigerant circuit 10 is pressure-equalized as a state when the refrigerant circuit 10 is pumped down. The pump-down operation is performed only when the suction pressure Ps detected after that is equal to or higher than the first threshold pressure Pst1. Thereby, when performing a pump-down operation, seizure of the compression mechanism part of the compressor 21 and rupture of the compressor 21 can be prevented.

  In the air conditioner 1 of the present embodiment, after the pump-down operation is started, the pump-down operation is ended using the suction pressure Ps detected after the first predetermined time tp1 has elapsed from the start of the pump-down operation. Judge whether to do. As a result, the suction pressure Ps is detected immediately after the start of the pump-down operation, and the detected suction pressure Ps is equal to or lower than the second threshold pressure Pst2, so that the pump-down operation is not stopped.

  Furthermore, in the air conditioning apparatus 1 of the present embodiment, if the suction pressure Ps does not become the second threshold pressure Pst2 or less even after the second predetermined time tp2 has elapsed since the start of the pump down operation, the pump down operation is terminated. . Thereby, the pump-down operation which cannot be normally performed is terminated, and the amount of refrigerant leaking from the refrigerant circuit 10 can be suppressed.

DESCRIPTION OF SYMBOLS 1 Air conditioning apparatus 2 Outdoor unit 5 Indoor unit 21 Compressor 22 Four-way valve 23 Outdoor heat exchanger 24 Outdoor expansion valve 28 Outdoor fan 32 Suction pressure sensor 51 Indoor heat exchanger 52 Indoor expansion valve 55 Indoor fan 100 Refrigerant leak detection means 200 Outdoor unit control means 210 CPU
240 sensor input unit Ps suction pressure Pst1 first threshold pressure Pst2 second threshold pressure tp1 first predetermined time tp2 second predetermined time

Claims (2)

An air conditioning system having an air conditioning device and refrigerant leakage detection means,
The air conditioner includes an outdoor unit having a compressor, an outdoor heat exchanger, a four-way valve, and suction pressure detecting means for detecting a suction pressure of the compressor, an indoor unit having an indoor heat exchanger, and the outdoor unit And a refrigerant circuit that is formed by connecting the indoor unit with a liquid pipe and a gas pipe and encloses the refrigerant, and a control unit that performs drive control of the compressor,
The outdoor unit is connected to the liquid pipe and is capable of blocking a refrigerant flow between the outdoor unit and the liquid pipe, and is connected to the gas pipe and connected to the outdoor unit and the gas pipe. A gas side shut-off valve capable of shutting off the flow of refrigerant between the
The refrigerant leakage detection means detects refrigerant leakage from the refrigerant circuit and notifies the control means;
The control means includes
When receiving a notification from the refrigerant leakage detection means that refrigerant leakage in the refrigerant circuit has been detected,
The outdoor heat exchanger functions as a condenser and the indoor heat exchanger functions as an evaporator, and the liquid side closing valve is closed and the gas side closing valve is opened to drive the compressor. Thus, the pump down operation for recovering the refrigerant sealed in the refrigerant circuit to the outdoor unit is started,
If the suction pressure detected by the suction pressure detecting means is less than a predetermined threshold pressure after elapse of a predetermined first predetermined time from the start of the pump-down operation, the pump-down operation is terminated.
If the suction pressure does not become smaller than the predetermined threshold pressure even after a predetermined second predetermined time longer than the first predetermined time has elapsed since the start of the pump-down operation, the detected suction pressure is detected. Regardless of the pump down operation,
An air conditioning system characterized by that. The refrigerant leakage detection means is provided in the indoor unit.
The air conditioning system according to claim 1.

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