JP2009210142A - Air conditioner and refrigerant amount determining method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an air conditioner easily making a liquid temperature constant control even when an ambient temperature is lower than a prescribed temperature in determining a refrigerant amount. <P>SOLUTION: This air conditioner 1 includes: a refrigerant circuit 10; a switching mechanism 22 switching a cooling operation state and a heating operation state; a cutoff mechanism 38; a refrigerant detecting mechanism 39; an operation control means; and a refrigerant amount determining means. The cutoff mechanism can cut off the passing of refrigerant between a heat source side heat exchanger and a liquid refrigerant communication pipe in a cooling operation state. The refrigerant detecting means detects a state quantity relating to the amount of refrigerant existing at an upstream side of the cutoff mechanism in the cooling operation state. The operation control means performs liquid pipe closing control after making the liquid temperature constant control in a heating operation state, and then makes liquid refrigerant storing control in the cooling operation state thereafter. The refrigerant amount determining means determines an availability of the refrigerant amount in the refrigerant circuit on the basis of the state quantity relating to the refrigerant amount detected by the refrigerant detecting mechanism in the liquid refrigerant storing control. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an air conditioner and a refrigerant amount determination operation that perform optimal control in accordance with conditions at that time in an air conditioner and a refrigerant amount determination operation that determine the suitability of the refrigerant amount in a refrigerant circuit.

  Conventionally, a heat source unit having a compressor and a heat source side heat exchanger and a utilization unit having a utilization side expansion valve and a utilization side heat exchanger are connected via a liquid refrigerant communication pipe and a gas refrigerant communication pipe. In order to determine the suitability of the refrigerant amount in the refrigerant circuit of the air conditioner constituted by the air conditioner, the air conditioner is operated under predetermined conditions.

For example, as an operating condition for determining the amount of refrigerant, a refrigerant circuit includes a use side expansion valve and a shutoff valve arranged on the upstream side of the liquid refrigerant communication pipe in the refrigerant flow direction in the refrigerant circuit when performing the cooling operation. The liquid refrigerant is sealed in the portion between the use side expansion valve and the shutoff valve including the liquid refrigerant communication pipe, and the circulation of the refrigerant in the refrigerant circuit is interrupted by the shutoff valve, thereby functioning as a condenser. Refrigerant condensed in the heat source side heat exchanger is retained in the refrigerant circuit upstream of the shutoff valve and downstream of the compressor, and the compressor is operated to communicate with the use side heat exchanger and gas refrigerant. In the refrigerant circuit such as piping, the refrigerant is present in the downstream side of the use-side expansion valve and in the upstream side of the compressor. In this state, the refrigerant detection mechanism In the refrigerant circuit, the state quantity related to the quantity of the refrigerant concentrated on the upstream side of the shut-off valve and the downstream side of the compressor is detected, and an appropriate refrigerant quantity is determined (Patent Document) 1).
JP 2006-023072 A

  However, when the room temperature or the outside air temperature is lower than a predetermined temperature, the above-described refrigerant amount determination method is applied, and the liquid temperature is constant so that the liquid refrigerant temperature is controlled to be constant when the liquid refrigerant is contained. Control may be difficult for the following reasons. This is because the pressure on the high pressure side decreases when the room temperature or the outside air temperature is lower than the predetermined temperature, and particularly when the usage unit is installed at a position higher than the heat source unit, Thus, the liquid refrigerant is likely to be in a flash state, and it becomes difficult to fill the liquid pipe with the liquid refrigerant. Moreover, when the pressure on the high pressure side is reduced, the outlet temperature of the heat source side heat exchanger is lowered and deviates from the target temperature.

  An object of the present invention is to provide an air conditioner capable of facilitating constant liquid temperature control even when the room temperature or the outside air temperature is lower than a predetermined temperature when determining the amount of refrigerant. There is.

  An air conditioner according to a first aspect of the present invention includes a refrigerant circuit, a switching mechanism, a shut-off mechanism, a refrigerant detection mechanism, an operation control unit, and a refrigerant amount determination unit. The refrigerant circuit includes a heat source unit, a utilization unit, a liquid refrigerant communication pipe and a gas refrigerant communication pipe. The heat source unit includes a compressor and a heat source side heat exchanger. The utilization unit has a utilization side expansion mechanism and a utilization side heat exchanger. The liquid refrigerant communication pipe and the gas refrigerant communication pipe connect the heat source unit and the utilization unit. The switching mechanism can switch between a cooling operation state and a heating operation state. The cooling operation state is a cooling operation in which the heat source side heat exchanger functions as a refrigerant condenser compressed in the compressor, and the use side heat exchanger functions as a refrigerant evaporator condensed in the heat source side heat exchanger. It is the state of the refrigerant circuit which performs. The heating operation state is a heating operation in which the use side heat exchanger functions as a refrigerant condenser compressed in the compressor, and the heat source side heat exchanger functions as a refrigerant evaporator condensed in the use side heat exchanger. It is the state of the refrigerant circuit in the case of performing. The shut-off mechanism is arranged on the downstream side of the heat source side heat exchanger and the upstream side of the liquid refrigerant communication pipe in the flow direction of the refrigerant in the cooling operation, and can block the passage of the refrigerant. The refrigerant detection mechanism is arranged upstream of the blocking mechanism in the refrigerant flow direction in the cooling operation, and detects a state quantity related to the amount of refrigerant existing upstream of the blocking mechanism. The operation control means is a heating operation state in which the liquid temperature constant control is performed so that the refrigerant temperature in the liquid refrigerant pipe portion between the use side expansion mechanism including the liquid refrigerant communication pipe and the shutoff mechanism in the refrigerant circuit becomes a constant value. Is performed, the liquid pipe closing control for closing the shut-off mechanism and the use side expansion mechanism is performed, and then the liquid refrigerant storage control for storing the liquid refrigerant in the upstream portion of the shut-off mechanism is performed in the cooling operation state. The refrigerant amount determination means determines whether or not the refrigerant amount in the refrigerant circuit is appropriate based on the state quantity related to the refrigerant amount detected by the refrigerant detection mechanism in the liquid refrigerant storage control.

  In the air conditioner of the present invention, operation control is performed so that the temperature of the liquid refrigerant flowing through the liquid refrigerant pipe portion between the utilization side expansion mechanism including the liquid refrigerant communication pipe and the shut-off mechanism in the refrigerant circuit becomes a constant value. The means controls in the heating operation state (hereinafter, liquid temperature constant control). By performing this liquid temperature constant control, the inside of the liquid refrigerant pipe portion is stably sealed by the liquid refrigerant at a constant temperature. As a result, the temperature of the refrigerant sent from the heat source side heat exchanger to the utilization side expansion mechanism through the liquid refrigerant communication pipe is adjusted to be constant, and the amount of refrigerant fixed inside the liquid refrigerant pipe portion is maintained. By closing the side expansion mechanism and the blocking mechanism, the amount of liquid refrigerant fixed to the liquid refrigerant pipe portion of the refrigerant circuit is contained (hereinafter referred to as liquid pipe closing control). Then, with the liquid refrigerant contained in the liquid refrigerant piping portion, the operation control means performs liquid refrigerant storage control for storing the liquid refrigerant in the upstream portion of the shut-off mechanism in the cooling operation state, and stored on the upstream side of the shut-off mechanism. The refrigerant detection mechanism detects a state quantity related to the refrigerant quantity of the liquid refrigerant, and the refrigerant quantity determination means determines whether the refrigerant quantity in the refrigerant circuit is appropriate based on the state quantity.

  Thus, in the air conditioning apparatus of the present invention, since the liquid temperature constant control is performed in the heating operation state, for example, even when the outside air temperature or the room temperature is lower than a predetermined temperature (the utilization unit is higher than the heat source unit). The pressure on the high-pressure side can be maintained at a predetermined pressure compared to the one that performs constant liquid temperature control in the cooling operation state, especially when installed at a position, so that the liquid refrigerant pipe does not flash. can do. In addition, if the liquid temperature constant control is performed in the cooling operation state when the outside air temperature is low, even when the room temperature is sufficiently high at the start of the liquid temperature constant control, the room temperature is lowered by the cooling during the operation, and the cooling operation is being performed. However, if the liquid temperature constant control is performed in a heating operation state, the room temperature is prevented from being lowered by heating the room, and the liquid temperature constant control is performed in a more stable state. be able to. Therefore, in the present invention, even when the outside air temperature or the room temperature is lower than the predetermined temperature, the liquid temperature constant control can be performed in a stable state, and based on the state quantity related to the refrigerant amount with less error. The suitability of the amount of refrigerant in the refrigerant circuit can be determined.

  An air conditioner according to a second aspect of the present invention is the air conditioner according to the first aspect of the present invention, wherein the operation control means performs the liquid temperature constant control in the heating operation state when the predetermined condition is satisfied, and then closes the liquid pipe Thereafter, the liquid refrigerant storage control is performed in the cooling operation state. Further, when the predetermined condition is not satisfied, the operation control means performs the liquid pipe closing control after performing the liquid temperature constant control in the cooling operation state, and further performs the liquid refrigerant storage control thereafter in the cooling operation state.

  In the air conditioner of the present invention, the liquid temperature constant control performed by the operation control means is performed in the heating operation state when the predetermined condition is satisfied, and is performed in the cooling operation state when the predetermined condition is not satisfied. When the predetermined condition is satisfied (for example, when the outside air temperature is lower than the predetermined temperature), when the liquid temperature constant control is performed in the heating operation state, the state of the liquid refrigerant flowing through the liquid refrigerant pipe portion is flushed. A stable state with few states can be obtained. On the other hand, when the predetermined condition is not satisfied (for example, when the outside air temperature is higher than the predetermined temperature), if the liquid temperature constant control is performed in the cooling operation state, the liquid refrigerant pipe portion is circulated. The state of the liquid refrigerant can be a stable state with few flash states.

  Therefore, in the air conditioner of the present invention, the state of the liquid refrigerant in the liquid refrigerant pipe portion in the liquid temperature constant control can be made stable in accordance with ambient conditions such as the outside air temperature and the room temperature. it can. For this reason, it is possible to determine the suitability of the refrigerant amount in the refrigerant circuit based on the state quantity related to the refrigerant quantity with less error.

  An air conditioner according to a third aspect of the present invention is the air conditioner according to the second aspect of the present invention, wherein the predetermined condition is that the room temperature in the room where the utilization unit is installed is lower than the first predetermined temperature, and / or This is a case where the outdoor temperature outside the room where the heat source unit is installed is lower than the second predetermined temperature.

  In the air conditioner of the present invention, the constant liquid temperature control performed by the operation control means is performed when the indoor temperature is lower than the first predetermined temperature and / or when the outdoor temperature is lower than the second predetermined temperature. This is performed in the cooling operation state when the room temperature is equal to or higher than the first predetermined temperature and / or when the outdoor temperature is equal to or higher than the second predetermined temperature.

  Therefore, in the air conditioner of the present invention, the state of the liquid refrigerant inside the liquid refrigerant pipe portion can be made stable in the liquid temperature constant control in accordance with the room temperature and / or the outside air temperature. For this reason, the suitability of the refrigerant quantity in the refrigerant circuit can be determined based on the state quantity relating to the refrigerant quantity in a state with less error.

  A refrigerant amount determination method according to a fourth aspect of the present invention includes a heat source unit having a compressor and a heat source side heat exchanger, a utilization unit having a utilization side expansion mechanism and a utilization side heat exchanger, a heat source unit and a utilization unit. A refrigerant circuit including a liquid refrigerant communication pipe and a gas refrigerant communication pipe to be connected, a heat source side heat exchanger as a refrigerant condenser to be compressed in the compressor, and a use side heat exchanger as heat source side heat exchange A cooling operation state in which the cooling operation is performed to function as an evaporator of the refrigerant condensed in the cooler, the use side heat exchanger as the refrigerant condenser to be compressed in the compressor, and the heat source side heat exchanger in the use side In an air conditioner having a switching mechanism that is capable of switching between a heating operation state that performs a heating operation that functions as an evaporator of refrigerant condensed in a heat exchanger, the amount of refrigerant in the refrigerant circuit A refrigerant amount determination method for determining whether or not a refrigerant passage is arranged on a downstream side of a heat source side heat exchanger and an upstream side of a liquid refrigerant communication pipe in a refrigerant flow direction in a refrigerant circuit when performing a cooling operation. In the heating operation state, the liquid temperature constant control is performed so that the refrigerant temperature in the liquid refrigerant pipe portion between the shut-off mechanism capable of shutting off and the use-side expansion mechanism becomes a constant value, and the shut-off mechanism and the use-side expansion mechanism The liquid refrigerant closing control is performed in the cooling operation state to store the liquid refrigerant in the upstream portion of the shut-off mechanism, and the coolant circuit is shut off in the refrigerant flow direction when performing the cooling operation. The state quantity related to the refrigerant amount existing upstream of the shut-off mechanism is detected by the refrigerant detection mechanism that is arranged upstream of the mechanism and detects the state quantity related to the refrigerant amount existing upstream of the shut-off mechanism, and the liquid Based on the state quantity relating to the refrigerant quantity refrigerant detection mechanism has detected in the medium reservoir control, it determines the adequacy of the refrigerant quantity in the refrigerant circuit.

  In the refrigerant quantity determination method of the present invention, the operation is performed so that the temperature of the liquid refrigerant flowing through the liquid refrigerant pipe portion between the use-side expansion mechanism including the liquid refrigerant communication pipe and the cutoff mechanism in the refrigerant circuit becomes a constant value. The control means controls in the heating operation state. By performing this liquid temperature constant control, the inside of the liquid refrigerant pipe portion is stably sealed by the liquid refrigerant at a constant temperature. As a result, the temperature of the refrigerant sent from the heat source side heat exchanger to the utilization side expansion mechanism through the liquid refrigerant communication pipe is adjusted to be constant, and the amount of refrigerant fixed inside the liquid refrigerant pipe portion is maintained. By closing the side expansion mechanism and the shut-off mechanism, the amount of liquid refrigerant fixed to the liquid refrigerant pipe portion in the refrigerant circuit is contained. Then, with the liquid refrigerant contained in the liquid refrigerant piping portion, the operation control means performs liquid refrigerant storage control for storing the liquid refrigerant in the upstream portion of the shut-off mechanism in the cooling operation state, and stored on the upstream side of the shut-off mechanism. The refrigerant detection mechanism detects a state quantity related to the refrigerant quantity of the liquid refrigerant, and the refrigerant quantity determination means determines whether the refrigerant quantity in the refrigerant circuit is appropriate based on the state quantity.

  As described above, in the refrigerant amount determination method of the present invention, the liquid temperature constant control is performed in the heating operation state. Therefore, for example, even when the outside air temperature or the room temperature is lower than the predetermined temperature, the liquid temperature is constant in the cooling operation state. The pressure on the high-pressure side can be maintained at a predetermined pressure as compared with the one that performs control, and the flash state can be prevented from being brought into the liquid refrigerant pipe. In addition, if the liquid temperature constant control is performed in the cooling operation state when the outside air temperature is low, even when the room temperature is sufficiently high at the start of the liquid temperature constant control, the room temperature is lowered by the cooling during the operation, and the cooling operation is being performed. However, if the liquid temperature constant control is performed in a heating operation state, the room temperature is prevented from being lowered by heating the room, and the liquid temperature constant control is performed in a more stable state. be able to. Therefore, in the present invention, even when the outside air temperature or the room temperature is lower than the predetermined temperature, the liquid temperature constant control can be performed in a stable state, and based on the state quantity related to the refrigerant amount with less error. The suitability of the amount of refrigerant in the refrigerant circuit can be determined.

  In the air conditioner according to the first aspect of the invention, since the liquid temperature constant control is performed in the heating operation state, the liquid temperature constant control is performed in the cooling operation state even when, for example, the outside air temperature or the room temperature is lower than a predetermined temperature. The pressure on the high-pressure side can be maintained at a predetermined pressure as compared with the above, and it is possible to prevent the liquid refrigerant pipe from being flushed. In addition, if the liquid temperature constant control is performed in the cooling operation state when the outside air temperature is low, even when the room temperature is sufficiently high at the start of the liquid temperature constant control, the room temperature is lowered by the cooling during the operation, and the cooling operation is being performed. However, if the liquid temperature constant control is performed in a heating operation state, the room temperature is prevented from being lowered by heating the room, and the liquid temperature constant control is performed in a more stable state. be able to. Therefore, in the present invention, even when the outside air temperature or the room temperature is lower than the predetermined temperature, the liquid temperature constant control can be performed in a stable state, and based on the state quantity related to the refrigerant amount with less error. The suitability of the amount of refrigerant in the refrigerant circuit can be determined.

  In the air conditioner according to the second aspect of the present invention, the state of the liquid refrigerant inside the liquid refrigerant pipe portion in the constant liquid temperature control can be made stable in accordance with ambient conditions such as the outside air temperature and the room temperature. it can. For this reason, it is possible to determine the suitability of the refrigerant amount in the refrigerant circuit based on the state quantity related to the refrigerant quantity with less error.

  In the air conditioner according to the third aspect of the invention, the state of the liquid refrigerant inside the liquid refrigerant pipe portion can be made stable in the liquid temperature constant control in accordance with the room temperature and / or the outside air temperature. For this reason, the suitability of the refrigerant quantity in the refrigerant circuit can be determined based on the state quantity relating to the refrigerant quantity in a state with less error.

  In the refrigerant quantity determination method according to the fourth aspect of the invention, since the liquid temperature constant control is performed in the heating operation state, the liquid temperature constant control is performed in the cooling operation state even when, for example, the outside air temperature or the room temperature is lower than a predetermined temperature. The pressure on the high-pressure side can be maintained at a predetermined pressure compared to what is performed, and the liquid refrigerant pipe can be prevented from being in a flush state. In addition, if the liquid temperature constant control is performed in the cooling operation state when the outside air temperature is low, even when the room temperature is sufficiently high at the start of the liquid temperature constant control, the room temperature is lowered by the cooling during the operation, and the cooling operation is being performed. However, if the liquid temperature constant control is performed in a heating operation state, the room temperature is prevented from being lowered by heating the room, and the liquid temperature constant control is performed in a more stable state. be able to. Therefore, in the present invention, even when the outside air temperature or the room temperature is lower than the predetermined temperature, the liquid temperature constant control can be performed in a stable state, and based on the state quantity related to the refrigerant amount with less error. The suitability of the amount of refrigerant in the refrigerant circuit can be determined.

  Hereinafter, an embodiment of an air-conditioning apparatus and a refrigerant amount determination method according to the present invention will be described based on the drawings.

(First embodiment)
(1) Configuration of Air Conditioner FIG. 1 is a schematic configuration diagram of an air conditioner 1 according to the first embodiment of the present invention. The air conditioner 1 is an apparatus used for air conditioning in a room such as a building by performing a vapor compression refrigeration cycle operation. The air conditioner 1 mainly includes an outdoor unit 2 as one heat source unit, indoor units 4 and 5 as a plurality of (two in the present embodiment) usage units connected in parallel thereto, and an outdoor unit. A liquid refrigerant communication pipe 6 and a gas refrigerant communication pipe 7 are provided as refrigerant communication pipes connecting the unit 2 and the indoor units 4 and 5. That is, the vapor compression refrigerant circuit 10 of the air conditioner 1 of the present embodiment includes the outdoor unit 2, the indoor units 4, 5, the liquid refrigerant communication pipe 6, and the gas refrigerant communication pipe 7. It is configured.

<Indoor unit>
The indoor units 4 and 5 are installed by embedding or hanging in a ceiling of a room such as a building or by hanging on a wall surface of the room. The indoor units 4 and 5 are connected to the outdoor unit 2 via a liquid refrigerant communication pipe 6 and a gas refrigerant communication pipe 7 and constitute a part of the refrigerant circuit 10.

  Next, the configuration of the indoor units 4 and 5 will be described. In addition, since the indoor unit 4 and the indoor unit 5 have the same configuration, only the configuration of the indoor unit 4 will be described here, and the configuration of the indoor unit 5 is the 40th number indicating each part of the indoor unit 4. The reference numerals in the 50s are attached instead of the reference numerals, and description of each part is omitted.

  The indoor unit 4 mainly has an indoor refrigerant circuit 10a (in the indoor unit 5, the indoor refrigerant circuit 10b) that constitutes a part of the refrigerant circuit 10. This indoor refrigerant circuit 10a mainly has an indoor expansion valve 41 as a use side expansion mechanism and an indoor heat exchanger 42 as a use side heat exchanger.

  In the present embodiment, the indoor expansion valve 41 is an electric expansion valve connected to the liquid side of the indoor heat exchanger 42 in order to adjust the flow rate of the refrigerant flowing in the indoor refrigerant circuit 10a. It is also possible to block the passage.

  In the present embodiment, the indoor heat exchanger 42 is a cross-fin type fin-and-tube heat exchanger composed of heat transfer tubes and a large number of fins, and functions as a refrigerant evaporator during cooling operation. It is a heat exchanger that cools indoor air and functions as a refrigerant condenser during heating operation to heat indoor air. In the present embodiment, the indoor heat exchanger 42 is a cross-fin type fin-and-tube heat exchanger, but is not limited thereto, and may be another type of heat exchanger.

  In the present embodiment, the indoor unit 4 sucks indoor air into the unit, exchanges heat with the refrigerant in the indoor heat exchanger 42, and then supplies the indoor fan 43 as a blower fan to be supplied indoors as supply air. have. The indoor fan 43 is a fan capable of changing the air volume supplied to the indoor heat exchanger 42. In this embodiment, the indoor fan 43 is a centrifugal fan or a multiblade fan driven by a motor 43m formed of a DC fan motor or the like. Etc.

  The indoor unit 4 is provided with various sensors. On the liquid side of the indoor heat exchanger 42, a liquid side temperature sensor 44 that detects the temperature of the refrigerant (that is, the refrigerant temperature corresponding to the condensation temperature during heating operation or the evaporation temperature during cooling operation) is provided. A gas side temperature sensor 45 that detects the temperature of the refrigerant is provided on the gas side of the indoor heat exchanger 42. An indoor temperature sensor 46 that detects the temperature of indoor air flowing into the unit (that is, the indoor temperature) is provided on the indoor air inlet side of the indoor unit 4. In the present embodiment, the liquid side temperature sensor 44, the gas side temperature sensor 45, and the room temperature sensor 46 are thermistors. The indoor unit 4 also has an indoor control unit 47 that controls the operation of each part constituting the indoor unit 4. And the indoor side control part 47 has the microcomputer, memory, etc. which were provided in order to control the indoor unit 4, and is with the remote control (not shown) for operating the indoor unit 4 separately. Control signals and the like can be exchanged between them, and control signals and the like can be exchanged with the outdoor unit 2 via the transmission line 8a.

<Outdoor unit>
The outdoor unit 2 is installed outside a building or the like, and is connected to the indoor units 4 and 5 via the liquid refrigerant communication pipe 6 and the gas refrigerant communication pipe 7, and the refrigerant circuit 10 is connected to the indoor units 4 and 5 together. It is composed.

  Next, the configuration of the outdoor unit 2 will be described. The outdoor unit 2 mainly has an outdoor refrigerant circuit 10 c that constitutes a part of the refrigerant circuit 10. The outdoor refrigerant circuit 10c mainly includes a compressor 21, a four-way switching valve 22, an outdoor heat exchanger 23 as a heat source side heat exchanger, an outdoor expansion valve 38 as an expansion mechanism, an accumulator 24, It has a supercooler 25 as a temperature adjusting mechanism, a liquid side closing valve 26, and a gas side closing valve 27.

  The compressor 21 is a compressor whose operating capacity can be varied. In the present embodiment, the compressor 21 is a positive displacement compressor driven by a motor 21m whose rotation speed is controlled by an inverter. In addition, in this embodiment, although the compressor 21 is only one unit, it is not limited to this, Two or more compressors may be connected in parallel according to the number of connected indoor units or the like. .

  The four-way switching valve 22 is a valve for switching the flow direction of the refrigerant. During the cooling operation, the outdoor heat exchanger 23 is used as a refrigerant condenser compressed by the compressor 21 and the indoor heat exchanger 42. , 52 is connected to the discharge side of the compressor 21 and the gas side of the outdoor heat exchanger 23 in order to function as an evaporator of refrigerant condensed in the outdoor heat exchanger 23 (specifically Specifically, the accumulator 24) and the gas refrigerant communication pipe 7 side are connected (cooling operation state: refer to the solid line of the four-way switching valve 22 in FIG. 1), and the indoor heat exchangers 42 and 52 are compressed during the heating operation. In order to allow the outdoor heat exchanger 23 to function as a refrigerant evaporator to be condensed in the indoor heat exchangers 42 and 52, as a refrigerant condenser compressed by the machine 21, the discharge side of the compressor 21 and the gas refrigerant Contact With connecting the 7-side it is possible to connect the gas side of the suction side and the outdoor heat exchanger 23 of the compressor 21 (the heating operation state: see the broken lines of the four-way switching valve 22 in FIG. 1).

  In the present embodiment, the outdoor heat exchanger 23 is a cross-fin type fin-and-tube heat exchanger, and as shown in FIG. 2, heat mainly composed of a heat transfer tube and a large number of fins. It has an exchanger body 23a, a header 23b connected to the gas side of the heat exchanger body 23a, and a flow divider 23c connected to the liquid side of the heat exchanger body 23a. Here, FIG. 2 is a schematic view of the outdoor heat exchanger 23. The outdoor heat exchanger 23 is a heat exchanger that functions as a refrigerant condenser during the cooling operation and functions as a refrigerant evaporator during the heating operation. The outdoor heat exchanger 23 has a gas side connected to the four-way switching valve 22 and a liquid side connected to the outdoor expansion valve 38. Further, as shown in FIG. 2, the outdoor heat exchanger 23 is disposed on the upstream side of the liquid side shut-off valve 26 in the refrigerant flow direction in the refrigerant circuit 10 when performing the cooling operation. A liquid level detection sensor 39 is provided as a refrigerant detection mechanism that detects a state quantity relating to the refrigerant quantity existing on the upstream side of the expansion valve 38. The liquid level detection sensor 39 is a sensor for detecting the amount of liquid refrigerant accumulated in the outdoor heat exchanger 23 as a state quantity related to the refrigerant amount existing on the upstream side of the outdoor expansion valve 38, and the outdoor heat exchanger. It is comprised by the tubular detection member arrange | positioned along the height direction of 23 (more specifically, header 23b). Here, in the case of the cooling operation, the high-temperature and high-pressure gas refrigerant discharged from the compressor 21 is cooled and condensed by the air supplied by the outdoor fan 28 in the outdoor heat exchanger 23, and the high-pressure liquid Becomes a refrigerant. That is, the liquid level detection sensor 39 detects a boundary between a region where the refrigerant exists in a gas state and a region where the refrigerant exists in the liquid state as a liquid level. The liquid level detection sensor 39 is not limited to such a tubular detection member. For example, the liquid level detection sensor 39 is arranged at a plurality of locations along the height direction of the outdoor heat exchanger 23 (more specifically, the header 23b). A boundary between a portion of the gas refrigerant higher than the ambient temperature of the outdoor heat exchanger 23 and a portion of the liquid refrigerant having a temperature similar to the ambient temperature of the outdoor heat exchanger 23. May be detected as a liquid level. In the present embodiment, the outdoor heat exchanger 23 is a cross-fin fin-and-tube heat exchanger, but is not limited to this, and may be another type of heat exchanger. In this embodiment, the header 23b is provided at one end of the heat exchanger main body 23a, and the flow divider 23c is provided at the other end of the heat exchanger main body 23a. The heat exchanger 23c may be provided at the same end of the heat exchanger body 23a.

  In the present embodiment, the outdoor expansion valve 38 performs outdoor heat exchange in the refrigerant flow direction in the refrigerant circuit 10 during the cooling operation in order to adjust the pressure, flow rate, and the like of the refrigerant flowing in the outdoor refrigerant circuit 10c. This is an electric expansion valve disposed downstream of the cooler 23 and upstream of the subcooler 25 (in this embodiment, connected to the liquid side of the outdoor heat exchanger 23), and allows passage of refrigerant. It is also possible to shut off.

  In the present embodiment, the outdoor unit 2 has an outdoor fan 28 as a blower fan for sucking outdoor air into the unit, exchanging heat with the refrigerant in the outdoor heat exchanger 23, and then discharging the air outside. ing. The outdoor fan 28 is a fan capable of changing the air volume supplied to the outdoor heat exchanger 23. In the present embodiment, the outdoor fan 28 is a propeller fan or the like driven by a motor 28m composed of a DC fan motor or the like. .

  The accumulator 24 is connected between the four-way selector valve 22 and the compressor 21 and can accumulate surplus refrigerant generated in the refrigerant circuit 10 in accordance with fluctuations in the operating load of the indoor units 4 and 5. It is a container.

  In this embodiment, the supercooler 25 is configured by bringing a double-pipe heat exchanger or a refrigerant pipe through which the refrigerant condensed in the heat source side heat exchanger flows into contact with a bypass refrigerant pipe 61 described later. In order to cool the refrigerant sent to the indoor expansion valves 41, 51 after being condensed in the outdoor heat exchanger 23, the pipe heat exchanger is provided between the outdoor heat exchanger 23 and the liquid refrigerant communication pipe 6. Is provided. More specifically, the supercooler 25 is connected between the outdoor expansion valve 38 and the liquid side closing valve 26.

  In the present embodiment, a bypass refrigerant pipe 61 as a cooling source for the subcooler 25 is provided. In the following description, a portion excluding the bypass refrigerant pipe 61 from the refrigerant circuit 10 will be referred to as a main refrigerant circuit for convenience. The bypass refrigerant pipe 61 branches a part of the refrigerant sent from the outdoor heat exchanger 23 to the indoor expansion valves 41 and 51 from the main refrigerant circuit, depressurizes the branched refrigerant, and then introduces the refrigerant into the subcooler 25. After the heat exchange with the refrigerant sent from the outdoor heat exchanger 23 to the indoor expansion valves 41 and 51 through the liquid refrigerant communication pipe 6, the main refrigerant circuit is connected to return to the suction side of the compressor 21. Specifically, the bypass refrigerant pipe 61 branches a part of the refrigerant sent from the outdoor expansion valve 38 to the indoor expansion valves 41 and 51 from a position between the outdoor heat exchanger 23 and the subcooler 25. A branch pipe 64 connected, a merging pipe 65 connected to the suction side of the compressor 21 so as to return from the outlet of the bypass refrigerant pipe side of the subcooler 25 to the suction side of the compressor 21, and a bypass refrigerant pipe 61 And a bypass expansion valve 62 as a communication pipe expansion mechanism for adjusting the flow rate of the flowing refrigerant. Here, the bypass expansion valve 62 is an electric expansion valve. Thereby, the refrigerant sent from the outdoor heat exchanger 23 to the indoor expansion valves 41 and 51 is cooled by the refrigerant flowing through the bypass refrigerant pipe 61 after being depressurized by the bypass expansion valve 62 in the supercooler 25. That is, the capacity control of the subcooler 25 is performed by adjusting the opening degree of the bypass expansion valve 62. Further, as will be described later, the bypass refrigerant pipe 61 may be a communication pipe that connects a portion of the refrigerant circuit 10 between the liquid side closing valve 26 and the outdoor expansion valve 38 and a portion on the suction side of the compressor 21. It is supposed to function. In the present embodiment, the bypass refrigerant pipe 61 is provided so as to branch the refrigerant from a position between the outdoor expansion valve 38 and the subcooler 25, but is not limited thereto, and the outdoor expansion valve 38 is not limited thereto. And the liquid side closing valve 26 may be provided so as to branch the refrigerant from the position.

  The liquid side shutoff valve 26 and the gas side shutoff valve 27 are valves provided at connection ports with external devices and pipes (specifically, the liquid refrigerant communication pipe 6 and the gas refrigerant communication pipe 7). The liquid side shut-off valve 26 is disposed downstream of the outdoor expansion valve 38 and upstream of the liquid refrigerant communication pipe 6 in the refrigerant flow direction in the refrigerant circuit 10 during the cooling operation (in the present embodiment). Is connected to the subcooler 25), and it is possible to block the passage of the refrigerant. The gas side closing valve 27 is connected to the four-way switching valve 22.

  The outdoor unit 2 is provided with various sensors in addition to the liquid level detection sensor 39 described above. Specifically, in the outdoor unit 2, a suction pressure sensor 29 that detects the suction pressure of the compressor 21, a discharge pressure sensor 30 that detects the discharge pressure of the compressor 21, and a suction temperature of the compressor 21 are detected. An intake temperature sensor 31 and a discharge temperature sensor 32 that detects the discharge temperature of the compressor 21 are provided. A liquid pipe temperature sensor 35 that detects the temperature of the refrigerant (that is, the liquid pipe temperature) is provided at the outlet of the subcooler 25 on the main refrigerant circuit side. The junction pipe 65 of the bypass refrigerant pipe 61 is provided with a bypass temperature sensor 63 for detecting the temperature of the refrigerant flowing through the outlet of the subcooler 25 on the bypass refrigerant pipe side. An outdoor temperature sensor 36 for detecting the temperature of the outdoor air flowing into the unit (that is, the outdoor temperature) is provided on the outdoor air inlet side of the outdoor unit 2. In the present embodiment, the suction temperature sensor 31, the discharge temperature sensor 32, the liquid pipe temperature sensor 35, the outdoor temperature sensor 36, and the bypass temperature sensor 63 are composed of thermistors. The outdoor unit 2 also has an outdoor control unit 37 that controls the operation of each unit constituting the outdoor unit 2. The outdoor control unit 37 includes a microcomputer provided to control the outdoor unit 2, an inverter circuit that controls the memory and the motor 21 m, and the like. Control signals and the like can be exchanged with 47 and 57 via the transmission line 8a. That is, the control part 8 which performs operation control of the whole air conditioning apparatus 1 is comprised by the indoor side control parts 47 and 57, the outdoor side control part 37, and the transmission line 8a which connects between the control parts 37, 47 and 57. Yes.

  As shown in FIG. 3, the control unit 8 is connected so that it can receive detection signals of various sensors 29 to 32, 35, 36, 39, 44 to 46, 54 to 56, 63, and these Various devices and valves 21, 22, 28, 38, 41, 43, 51, 53, and 62 are connected based on the detection signal and the like. Moreover, various data are stored in the memory which comprises the control part 8, for example, the appropriateness | suitableness of the refrigerant circuit 10 of the air conditioning apparatus 1 for every property in which the piping length etc. after being constructed in the building were considered Refrigerant amount data and the like are stored. Then, the control unit 8 reads out these data when performing the automatic refrigerant charging operation and the refrigerant leakage detection operation, which will be described later, and fills the refrigerant circuit 10 with an appropriate amount of refrigerant, or the appropriate refrigerant amount data. The presence or absence of refrigerant leakage is judged by comparing with the above. In addition to the appropriate refrigerant amount data (appropriate refrigerant amount Z), the memory of the control unit 8 stores liquid pipe determined refrigerant amount data (liquid pipe determined refrigerant amount Y) and outdoor heat exchanger collected refrigerant amount data (outdoor The heat exchange collected refrigerant amount X) is stored, and the relationship of Z = X + Y is satisfied. Here, the liquid pipe determined refrigerant amount Y extends from the downstream side of the outdoor heat exchanger 23 described later to the indoor expansion valves 41 and 51 via the outdoor expansion valve 38, the subcooler 25, and the liquid refrigerant communication pipe 6. This is the amount of refrigerant fixed to this portion when the operation of sealing the portion with the liquid refrigerant at a constant temperature is performed. The outdoor heat exchange collected refrigerant amount X is a refrigerant amount obtained by subtracting the liquid pipe fixed refrigerant amount Y from the appropriate refrigerant amount Z. Further, the memory of the control unit 8 stores a relational expression that can calculate the amount of refrigerant accumulated from the outdoor expansion valve 38 to the outdoor heat exchanger 23 based on the liquid level data of the outdoor heat exchanger 23. Here, FIG. 3 is a control block diagram of the air conditioner 1.

<Refrigerant communication piping>
Refrigerant communication pipes 6 and 7 are refrigerant pipes constructed on site when the air conditioner 1 is installed at an installation location such as a building, and installation conditions such as the installation location and a combination of an outdoor unit and an indoor unit. Those having various lengths and tube diameters are used. For this reason, for example, when a new air conditioner is installed, the air conditioner 1 is filled with an appropriate amount of refrigerant according to the installation conditions such as the length and pipe diameter of the refrigerant communication pipes 6 and 7. There is a need to.

  As described above, the refrigerant circuit 10 of the air conditioner 1 is configured by connecting the indoor refrigerant circuits 10a and 10b, the outdoor refrigerant circuit 10c, and the refrigerant communication pipes 6 and 7. The air conditioner 1 of the present embodiment is operated by switching the cooling operation and the heating operation by the four-way switching valve 22 by the control unit 8 including the indoor side control units 47 and 57 and the outdoor side control unit 37. In addition, the devices of the outdoor unit 2 and the indoor units 4 and 5 are controlled in accordance with the operation load of the indoor units 4 and 5.

(2) Operation | movement of an air conditioning apparatus Next, operation | movement of the air conditioning apparatus 1 of this embodiment is demonstrated.

  As an operation mode of the air conditioner 1 of the present embodiment, a normal operation mode for controlling the components of the outdoor unit 2 and the indoor units 4 and 5 according to the operation load of the indoor units 4 and 5, and an air conditioner When the test operation is performed after the installation of the component 1 or the like, the refrigerant automatic charging operation mode in which the refrigerant circuit 10 is charged with an appropriate amount of refrigerant, and the test operation including such an automatic refrigerant charging operation are terminated and the normal operation is performed. There is a refrigerant leakage detection operation mode in which the presence or absence of refrigerant leakage from the refrigerant circuit 10 is determined after starting the operation.

  Hereinafter, the operation | movement in each operation mode of the air conditioning apparatus 1 is demonstrated.

<Normal operation mode>
First, the cooling operation in the normal operation mode will be described with reference to FIG.

  During the cooling operation, the four-way switching valve 22 is in the state indicated by the solid line in FIG. 1 (cooling operation state), that is, the discharge side of the compressor 21 is connected to the gas side of the outdoor heat exchanger 23 and the compressor 21 Is in a state of being connected to the gas side of the indoor heat exchangers 42 and 52 via the gas side closing valve 27 and the gas refrigerant communication pipe 7. Here, the outdoor expansion valve 38 and the bypass expansion valve 62 are fully opened, and the liquid side closing valve 26 and the gas side closing valve 27 are also opened.

  When the compressor 21, the outdoor fan 28, and the indoor fans 43 and 53 are operated in the state of the refrigerant circuit 10, the low-pressure gas refrigerant is sucked into the compressor 21 and compressed to become a high-pressure gas refrigerant. Thereafter, the high-pressure gas refrigerant is sent to the outdoor heat exchanger 23 via the four-way switching valve 22, exchanges heat with the outdoor air supplied by the outdoor fan 28, and condenses to form a high-pressure liquid refrigerant. Become. The high-pressure liquid refrigerant passes through the outdoor expansion valve 38, flows into the supercooler 25, and is further cooled by performing heat exchange with the refrigerant flowing through the bypass refrigerant pipe 61 to be in a supercooled state. At this time, a part of the high-pressure liquid refrigerant condensed in the outdoor heat exchanger 23 is branched to the bypass refrigerant pipe 61, decompressed by the bypass expansion valve 62, and then returned to the suction side of the compressor 21. Here, a part of the refrigerant passing through the bypass expansion valve 62 is evaporated by being depressurized to near the suction pressure of the compressor 21. And the refrigerant | coolant which flows toward the suction | inhalation side of the compressor 21 from the exit of the bypass expansion valve 62 of the bypass refrigerant | coolant piping 61 passes the subcooler 25, and the indoor unit 4 from the outdoor heat exchanger 23 by the side of a main refrigerant circuit. 5 and heat exchange with the high-pressure liquid refrigerant sent to 5.

  Then, the high-pressure liquid refrigerant in a supercooled state is sent to the indoor units 4 and 5 via the liquid-side closing valve 26 and the liquid refrigerant communication pipe 6.

  The high-pressure liquid refrigerant sent to the indoor units 4 and 5 is reduced to near the suction pressure of the compressor 21 by the indoor expansion valves 41 and 51 to become a low-pressure gas-liquid two-phase refrigerant and the indoor heat exchanger. The heat is exchanged with indoor air in the indoor heat exchangers 42 and 52 and evaporated to become a low-pressure gas refrigerant.

  The low-pressure gas refrigerant is sent to the outdoor unit 2 via the gas refrigerant communication pipe 7 and flows into the accumulator 24 via the gas-side closing valve 27 and the four-way switching valve 22. Then, the low-pressure gas refrigerant that has flowed into the accumulator 24 is again sucked into the compressor 21. As described above, in the air conditioner 1, the outdoor heat exchanger 23 is used as a refrigerant condenser to be compressed in the compressor 21, and the indoor heat exchangers 42 and 52 are condensed after being condensed in the outdoor heat exchanger 23. It is possible to perform at least a cooling operation that functions as an evaporator of the refrigerant sent through the refrigerant communication pipe 6 and the indoor expansion valves 41 and 51.

  Here, the refrigerant distribution state of the refrigerant circuit 10 during the cooling operation in the normal operation mode is as follows. As shown in FIG. 4, the refrigerant is in the liquid state (the hatched portion in FIG. 4), the gas-liquid The two-phase state (lattice hatched portion in FIG. 4) and the gas state (hatched hatched portion in FIG. 4) are distributed and distributed. Specifically, from the vicinity of the outlet of the outdoor heat exchanger 23 via the outdoor expansion valve 38, the indoor expansion valve 41, via the part on the main refrigerant circuit side of the subcooler 25 and the liquid refrigerant communication pipe 6, The part up to 51 and the part upstream of the bypass expansion valve 62 of the bypass refrigerant pipe 61 are filled with liquid refrigerant. Then, an intermediate part of the outdoor heat exchanger 23, a part of the bypass refrigerant pipe 61 on the upstream side of the bypass expansion valve 62, a part of the subcooler 25 on the side of the bypass refrigerant pipe and in the vicinity of the inlet, and indoor heat exchange Portions near the inlets of the vessels 42 and 52 are filled with a gas-liquid two-phase refrigerant. In addition, a part from the middle part of the indoor heat exchangers 42 and 52 to the inlet of the outdoor heat exchanger 23 via the gas refrigerant communication pipe 7 and the compressor 21, a part near the inlet of the outdoor heat exchanger 23, And the part by the side of the bypass refrigerant | coolant piping of the supercooler 25 until it merges to the suction | inhalation side of the compressor 21 of the bypass refrigerant | coolant piping 61 is satisfy | filled with the refrigerant | coolant of a gas state. Here, FIG. 4 is a schematic diagram showing a state of the refrigerant flowing in the refrigerant circuit 10 in the cooling operation.

  In the cooling operation in the normal operation mode, the refrigerant is distributed in the refrigerant circuit 10 in such a distribution. However, in the refrigerant amount determination operation in the refrigerant automatic charging operation mode and the refrigerant leakage detection operation mode described later, The distribution is a collection of liquid refrigerant in the liquid refrigerant communication pipe 6 and the outdoor heat exchanger 23 (see FIG. 6).

  Next, the heating operation in the normal operation mode will be described.

  During the heating operation, the four-way switching valve 22 is in the state indicated by the broken line in FIG. 1 (heating operation state), that is, the discharge side of the compressor 21 is exchanged indoors via the gas side closing valve 27 and the gas refrigerant communication pipe 7. The compressors 42 and 52 are connected to the gas side, and the suction side of the compressor 21 is connected to the gas side of the outdoor heat exchanger 23. The degree of opening of the outdoor expansion valve 38 is adjusted so as to reduce the refrigerant flowing into the outdoor heat exchanger 23 to a pressure at which the refrigerant can evaporate in the outdoor heat exchanger 23 (that is, evaporation pressure). . Further, the liquid side closing valve 26 and the gas side closing valve 27 are in an open state. The opening degree of the indoor expansion valves 41 and 51 is adjusted so that the degree of supercooling of the refrigerant at the outlets of the indoor heat exchangers 42 and 52 becomes constant at the target value of the degree of supercooling. In the present embodiment, the degree of refrigerant supercooling at the outlets of the indoor heat exchangers 42 and 52 is calculated by converting the discharge pressure of the compressor 21 detected by the discharge pressure sensor 30 into a saturation temperature value corresponding to the condensation temperature. It is detected by subtracting the refrigerant temperature value detected by the liquid side temperature sensors 44 and 54 from the saturation temperature value of the refrigerant. Although not adopted in this embodiment, a temperature sensor for detecting the temperature of the refrigerant flowing in each indoor heat exchanger 42, 52 is provided, and a refrigerant temperature value corresponding to the condensation temperature detected by this temperature sensor. May be subtracted from the refrigerant temperature value detected by the liquid-side temperature sensors 44 and 54 to detect the degree of supercooling of the refrigerant at the outlets of the indoor heat exchangers 42 and 52. The bypass expansion valve 62 is closed.

  When the compressor 21, the outdoor fan 28, and the indoor fans 43, 53 are operated in the state of the refrigerant circuit 10, the low-pressure gas refrigerant is sucked into the compressor 21 and compressed to become a high-pressure gas refrigerant. It is sent to the indoor units 4 and 5 via the valve 22, the gas side closing valve 27 and the gas refrigerant communication pipe 7.

  The high-pressure gas refrigerant sent to the indoor units 4 and 5 is condensed by exchanging heat with the indoor air in the outdoor heat exchangers 42 and 52 to become a high-pressure liquid refrigerant, and then the indoor expansion valve 41. , 51, the pressure is reduced according to the valve opening degree of the indoor expansion valves 41, 51.

  The refrigerant that has passed through the indoor expansion valves 41 and 51 is sent to the outdoor unit 2 via the liquid refrigerant communication pipe 6 and further reduced in pressure via the liquid side closing valve 26, the subcooler 25, and the outdoor expansion valve 38. Then, it flows into the outdoor heat exchanger 23. The low-pressure gas-liquid two-phase refrigerant flowing into the outdoor heat exchanger 23 exchanges heat with the outdoor air supplied by the outdoor fan 28 to evaporate into a low-pressure gas refrigerant. And flows into the accumulator 24. Then, the low-pressure gas refrigerant that has flowed into the accumulator 24 is again sucked into the compressor 21.

  The operation control in the normal operation mode as described above is performed by the control unit 8 (more specifically, the indoor side control units 47 and 57 and the outdoor side control functioning as the operation control means for performing the normal operation including the cooling operation and the heating operation. Transmission line 8a) connecting between the unit 37 and the control units 37, 47, 57.

<Automatic refrigerant charging operation mode>
Next, the refrigerant automatic charging operation mode performed during the trial operation will be described with reference to FIGS. Here, FIG. 5 is a flowchart of the refrigerant quantity determination operation. FIG. 6 is a cooling / heating determination graph for determining whether the liquid temperature constant control performed in step S1 described later is performed in the cooling operation state or the heating operation state in the refrigerant amount determination operation flowchart. FIG. 7 is a schematic diagram showing a state of the refrigerant flowing in the refrigerant circuit 10 in the refrigerant quantity determination operation. FIG. 8 is a diagram schematically showing the inside of the heat exchanger main body 23a and the header 23b of FIG. 2, and is a diagram showing how refrigerant is accumulated in the outdoor heat exchanger 23 in the refrigerant amount determination operation.

  The refrigerant automatic charging operation mode is an operation mode performed at the time of a test operation after installation of the components of the air conditioner 1, and an appropriate amount of refrigerant according to the volumes of the liquid refrigerant communication pipe 6 and the gas refrigerant communication pipe 7 Is automatically filled into the refrigerant circuit 10.

  First, the liquid side shut-off valve 26 and the gas side shut-off valve 27 of the outdoor unit 2 are opened, and the refrigerant circuit 10 is filled with the refrigerant filled in the outdoor unit 2 in advance.

  Next, an operator who performs the automatic refrigerant charging operation connects a refrigerant cylinder for additional charging to the refrigerant circuit 10 (for example, the suction side of the compressor 21) and starts charging.

  Then, when the operator issues a command to start the automatic refrigerant charging operation to the control unit 8 directly or by a remote controller (not shown) or the like, the control unit 8 causes the steps S1 to S9 shown in FIG. The refrigerant quantity determination operation involving the above process and the determination of the suitability of the refrigerant quantity are performed.

  In step S1, whether the constant liquid temperature control described later in the cooling operation state or the constant liquid temperature control in the heating operation state is performed, the outdoor temperature and the indoor temperature at that time are on the cooling side of the cooling / heating determination graph of FIG. Or whether it is on the heating side (operation state determination). This operation state determination graph is a determination criterion for determining whether the liquid temperature constant control is performed in the cooling operation state or the heating operation state. Here, if the point plotted based on the outside air temperature and the room temperature at that time is present above the straight line L with the straight line L as a boundary, the liquid temperature constant control is performed in the cooling operation state. If it exists on the lower side, the liquid temperature constant control is performed in the heating operation state. For example, when the outside air temperature is 0 ° C. and the room temperature is 0 ° C., the position is the point P in FIG. 6, and since the point P is in the heating operation state region, the liquid temperature constant control is performed in the heating operation state. become. In the operation state determination of the present embodiment, a point (for example, the point P) obtained by the outside air temperature and the room temperature is divided by a straight line L as shown in FIG. 6 (the cooling operation state region and the heating operation state). However, the division of these regions is not limited to a straight line, and may be performed by a quadratic curve or a cubic curve. If it is determined in step S1 that the liquid temperature constant control is performed in the cooling operation state, the process proceeds to step S2 and the processing in steps S2 to S4 described later is performed, and it is determined that the liquid temperature constant control is performed in the heating operation state. If so, the process proceeds to step S5, and the processes of steps S5 to S7 described later are performed.

  In step S2, the liquid temperature constant control is performed in the cooling operation state, and the device control is basically performed so as to perform the same operation as the cooling operation in the normal operation mode described above. However, the point that the liquid temperature constant control is performed is different from the cooling operation in the normal operation mode. In this liquid temperature constant control, condensing pressure control and liquid pipe temperature control are performed. In the condensation pressure control, the air volume of the outdoor air supplied to the outdoor heat exchanger 23 by the outdoor fan 28 is controlled so that the condensation pressure of the refrigerant in the outdoor heat exchanger 23 becomes constant. Since the condensing pressure of the refrigerant in the condenser changes more greatly than the influence of the outdoor temperature, the air volume of the indoor air supplied from the outdoor fan 28 to the outdoor heat exchanger 23 is controlled by the motor 28m. Thereby, the condensing pressure of the refrigerant in the outdoor heat exchanger 23 becomes constant, and the state of the refrigerant flowing in the condenser is stabilized. And between the outdoor heat exchanger 23 and the indoor expansion valves 41 and 51, the outdoor expansion valve 38, the part on the main refrigerant circuit side of the subcooler 25, the flow path including the liquid refrigerant communication pipe 6, and the outdoor heat exchanger The high-pressure liquid refrigerant flows through the flow path from 23 to the bypass expansion valve 62 of the bypass refrigerant pipe 61. Therefore, the refrigerant pressure in the portion from the outdoor heat exchanger 23 to the indoor expansion valves 41 and 51 and the bypass expansion valve 62 is also stabilized. In the condensation pressure control of this embodiment, the discharge pressure of the compressor 21 detected by the discharge pressure sensor 30 is used as the condensation pressure. Although not adopted in this embodiment, a temperature sensor that detects the temperature of the refrigerant flowing in the outdoor heat exchanger 23 is provided, and the refrigerant temperature value corresponding to the condensation temperature detected by this temperature sensor is set to the condensation pressure. May be used for controlling the condensation pressure. In the liquid pipe temperature control, unlike the superheat control in the cooling operation in the normal operation mode described above, the supercooler 25 is controlled so that the temperature of the refrigerant sent from the supercooler 25 to the indoor expansion valves 41 and 51 is constant. Control ability. More specifically, in the liquid pipe temperature control, the refrigerant temperature detected by the liquid pipe temperature sensor 35 provided at the outlet of the subcooler 25 on the main refrigerant circuit side is constant at the liquid pipe temperature target value. Next, the opening degree of the bypass expansion valve 62 of the bypass refrigerant pipe 61 is adjusted. Thereby, the refrigerant density in the refrigerant pipe including the liquid refrigerant communication pipe 6 extending from the outlet on the main refrigerant circuit side of the subcooler 25 to the indoor expansion valves 41 and 51 is stabilized.

  In step S3, it is determined whether or not the liquid temperature has reached a constant by performing the liquid temperature constant control in step S2. If it is determined that the liquid temperature is constant, the process proceeds to step S4. If it is determined that the liquid temperature is not yet constant, the liquid temperature constant control in step S2 is continued. become. Then, when the liquid temperature is controlled to be constant by the constant liquid temperature control, the liquid refrigerant communication pipe from the outlet on the main refrigerant circuit side of the subcooler 25 to the indoor expansion valves 41 and 51 in the hatched portion in FIG. The inside of the refrigerant pipe including 6 is stably sealed by the liquid refrigerant having a constant temperature.

  Thereby, in step S4 to be described later, the indoor expansion valves 41 and 51 and the outdoor expansion valve 38 are placed in a portion between the indoor expansion valves 41 and 51 including the liquid refrigerant communication pipe 6 in the refrigerant circuit 10 and the outdoor expansion valve 38. Before the liquid refrigerant is contained, the temperature of the refrigerant sent from the outdoor heat exchanger 23 to the indoor expansion valves 41 and 51 through the liquid refrigerant communication pipe 6 is adjusted to be constant by the subcooler 25, and the liquid refrigerant is communicated from the outdoor expansion valve 38. The liquid pipe fixed refrigerant amount Y, which is the amount of refrigerant fixed to the portion extending to the indoor expansion valves 41 and 51 via the pipe 6, is maintained.

  Next, in step S4, the indoor expansion valves 41 and 51 are fully closed, the bypass expansion valve 62 is fully closed, and the outdoor expansion valve 38 is fully closed, so that the liquid in the refrigerant circuit 10 is liquid. Liquid refrigerant is sealed in a portion between the indoor expansion valves 41 and 51 and the outdoor expansion valve 38 including the refrigerant communication pipe 6 (liquid pipe closing control). As a result, while the refrigerant amount of the liquid pipe determined refrigerant amount Y is maintained, the circulation of the refrigerant is interrupted, and the liquid refrigerant of the accurate liquid pipe determined refrigerant amount Y considering the refrigerant temperature is supplied to the refrigerant circuit 10. Of these, it can be contained in a portion between the indoor expansion valves 41 and 51 and the outdoor expansion valve 38 including the liquid refrigerant communication pipe 6. The operation of the compressor 21 and the outdoor fan 28 is continued even after the expansion valves 38, 41, 51 are fully closed. As a result, as shown in FIG. 7, the refrigerant condensed in the outdoor heat exchanger 23 functioning as a condenser is circulated in the refrigerant circuit 10 by the outdoor expansion valve 38, so that the outdoor heat In the exchanger 23, the refrigerant 23 is cooled and condensed by the outdoor air supplied by the outdoor fan 28, on the upstream side of the outdoor expansion valve 38 in the refrigerant circuit 10 such as the outdoor heat exchanger 23, and in the compressor 21. It will gradually accumulate in the downstream part. As a result, the refrigerant in the refrigerant circuit 10 is concentrated in a portion of the refrigerant circuit 10 upstream of the outdoor expansion valve 38 and downstream of the compressor 21. More specifically, as shown in FIG. 8, the refrigerant that has been condensed into a liquid state accumulates from the upstream side of the outdoor expansion valve 38 into the outdoor heat exchanger 23. As described above, since the liquid refrigerant is confined in the portion between the indoor expansion valves 41 and 51 including the liquid refrigerant communication pipe 6 and the outdoor expansion valve 38 in the refrigerant circuit 10, In the cooling operation, the amount of liquid refrigerant accumulated from the upstream side of the outdoor expansion valve 38 to the inside of the outdoor heat exchanger 23 is prevented from becoming excessive.

  Next, the process of step S5-step S7 when it determines with performing liquid temperature constant control in heating operation in step S1 is demonstrated.

  In step S5, liquid temperature constant control in the heating operation is performed, and device control is basically performed so as to perform the same operation as the heating operation in the normal operation mode described above. However, the point that the liquid temperature constant control is performed is different from the heating operation in the normal operation mode. In the liquid temperature constant control in the heating operation state, unlike the liquid temperature constant control in the cooling operation state, main expansion valve control and condenser liquid temperature control are performed. In the main expansion valve control, the indoor expansion valves 41 and 51 are opened 90%, and the indoor side liquid pipe temperature and the liquid pipe temperature sensor 35 detected by the liquid side temperature sensors 44 and 54 in the indoor heat exchanger are detected. Control by the outdoor expansion valve 38 is performed so that the difference from the outdoor liquid pipe temperature is equal to or less than the first target value. Here, the “first target value” is a threshold value for determining whether or not the liquid refrigerant condensed in the indoor heat exchangers 42 and 52 is flushed. That is, when the temperature difference detected here exists in the region below the “first target value”, it is determined that the liquid refrigerant condensed in the indoor heat exchangers 42 and 52 has not been flushed. Is done. Therefore, between the indoor heat exchangers 42 and 52 and the outdoor expansion valve 38, the flow paths including the indoor expansion valves 41 and 51, the liquid refrigerant communication pipe 6, the portion on the main refrigerant circuit side of the subcooler 25, and the bypass refrigerant. A high-pressure liquid refrigerant flows through the flow path from the bypass expansion valve 62 of the pipe 61 to the main refrigerant circuit. Therefore, the state of the refrigerant in the portions from the indoor heat exchangers 42 and 52 to the outdoor expansion valve 38 and the bypass expansion valve 62 is also stabilized. Although not adopted in the present embodiment, a pressure sensor for detecting the pressure of the liquid refrigerant between the liquid side closing valve 26 and the supercooler 25 is provided, and the pressure detected by the pressure sensor, It may be determined whether or not the liquid refrigerant is flushed by controlling the outdoor expansion valve 38 so that the outdoor liquid pipe temperature detected by the pipe temperature sensor 35 reaches the second target value. . In the condenser liquid temperature control, the opening degree of the indoor expansion valves 41 and 51 is controlled in the range of 80 to 100% so that the temperature of the refrigerant sent from the indoor expansion valves 41 and 51 to the outdoor expansion valve 38 becomes constant. . And in all the indoor units 4 and 5, the temperature of the refrigerant | coolant detected by the liquid side temperature sensors 44 and 52 provided in the exit of the indoor heat exchangers 42 and 52 becomes constant with a liquid pipe temperature target value. The opening degree of each of the indoor expansion valves 41 and 51 is adjusted. Thereby, the refrigerant density in the refrigerant pipe including the liquid refrigerant communication pipe 6 extending from the outlets of the indoor heat exchangers 42 and 52 to the outdoor expansion valve 38 is stabilized. Although not adopted in the present embodiment, a temperature sensor for detecting the temperature of the liquid refrigerant in the pipe between the indoor expansion valves 41 and 51 in the indoor units 4 and 5 and the liquid refrigerant communication pipe 6 is provided. You may adjust the opening degree of the indoor expansion valves 41 and 51 so that the liquid pipe temperature detected by this temperature sensor may become constant with the liquid pipe temperature target value.

  Next, in step S6, it is determined whether or not the liquid temperature has reached a constant by performing the liquid temperature constant control in step S5. If it is determined that the liquid temperature is constant, the process proceeds to step S7. If it is determined that the liquid temperature is not yet constant, the liquid temperature constant control in step S5 is continued. become. Then, when the liquid temperature is controlled to be constant by the constant liquid temperature control, the liquid refrigerant communication pipe from the outlet on the main refrigerant circuit side of the subcooler 25 to the indoor expansion valves 41 and 51 in the hatched portion in FIG. The inside of the refrigerant pipe including 6 is stably sealed by the liquid refrigerant having a constant temperature.

  Accordingly, in step S7 described later, the indoor expansion valves 41 and 51 and the liquid side closing valve 26 are used to connect the indoor expansion valves 41 and 51 including the liquid refrigerant communication pipe 6 in the refrigerant circuit 10 to the liquid side closing valve 26. Before the liquid refrigerant is confined in this part, the temperature of the refrigerant sent from the outdoor heat exchanger 23 to the indoor expansion valves 41 and 51 through the liquid refrigerant communication pipe 6 is adjusted to be constant by the subcooler 25, and the liquid side closing valve The liquid pipe fixed refrigerant amount Y, which is the amount of refrigerant fixed to the portion from 26 to the indoor expansion valves 41 and 51 through the liquid refrigerant communication pipe 6, is maintained.

  Next, in step S7, the indoor expansion valves 41 and 51 are fully closed, the bypass expansion valve 62 is fully closed, and the outdoor expansion valve 38 is fully closed, so that the liquid in the refrigerant circuit 10 is liquid. Liquid refrigerant is sealed in a portion between the indoor expansion valves 41 and 51 and the outdoor expansion valve 38 including the refrigerant communication pipe 6 (liquid pipe closing control). As a result, while the refrigerant amount of the liquid pipe determined refrigerant amount Y is maintained, the circulation of the refrigerant is interrupted, and the liquid refrigerant of the accurate liquid pipe determined refrigerant amount Y considering the refrigerant temperature is supplied to the refrigerant circuit 10. Of these, it can be contained in a portion between the indoor expansion valves 41 and 51 and the outdoor expansion valve 38 including the liquid refrigerant communication pipe 6. Thereafter, the operation of the compressor 21 is stopped, the four-way switching valve 22 is controlled, the state of the refrigerant circuit 10 is switched from the heating operation state to the cooling operation state, and the compressor 21 is operated again. In addition, when the compressor 21 is operated, the outdoor fan 28 is operated. Thus, as in step S4, as shown in FIG. 7, the refrigerant condensed in the outdoor heat exchanger 23 functioning as a condenser is not circulated in the refrigerant circuit 10 by the outdoor expansion valve 38. Therefore, in the outdoor heat exchanger 23, it is cooled and condensed by the outdoor air supplied by the outdoor fan 28, and on the upstream side of the outdoor expansion valve 38 in the refrigerant circuit 10 like the outdoor heat exchanger 23, In addition, it gradually accumulates in the downstream portion of the compressor 21. As a result, the refrigerant in the refrigerant circuit 10 is concentrated in a portion of the refrigerant circuit 10 upstream of the outdoor expansion valve 38 and downstream of the compressor 21. More specifically, as shown in FIG. 8, the refrigerant that has been condensed into a liquid state accumulates from the upstream side of the outdoor expansion valve 38 into the outdoor heat exchanger 23. As described above, since the liquid refrigerant is confined in the portion between the indoor expansion valves 41 and 51 including the liquid refrigerant communication pipe 6 and the outdoor expansion valve 38 in the refrigerant circuit 10, In the cooling operation, the amount of liquid refrigerant accumulated from the upstream side of the outdoor expansion valve 38 to the inside of the outdoor heat exchanger 23 is prevented from becoming excessive.

  Next, in step S <b> 8, the liquid level of the refrigerant accumulated in the outdoor heat exchanger 23 is detected by the liquid level detection sensor 39. Here, the liquid level detection sensor 39 detects the boundary between the region where the refrigerant exists in the gas state and the region where the refrigerant exists in the liquid state as the liquid level. Accordingly, the outdoor level heat exchange from the outdoor expansion valve 38 is performed by substituting the height h of the liquid level obtained by the liquid level detection sensor 39 (see FIG. 8) into the relational expression stored in the memory of the control unit 8. The amount of refrigerant accumulated over the vessel 23 is calculated.

  Next, in step S9, it is determined whether or not the refrigerant amount calculated in step S8 described above has reached the outdoor heat exchange collected refrigerant amount X stored in the memory of the control unit 8. If the outdoor heat exchange collected refrigerant amount X has not been reached, the process returns to step S8, the refrigerant circuit 10 is continuously charged with refrigerant, and it is determined that the outdoor heat exchange collected refrigerant amount X has been reached. If so, the charging of the refrigerant into the refrigerant circuit 10 is terminated. Accordingly, the liquid level detection sensor 39 can detect the state quantity related to the refrigerant amount collected in the upstream side of the outdoor expansion valve 38 and the downstream side of the compressor 21 in the refrigerant circuit 10. It is possible to determine the amount of refrigerant, and it is possible to determine an appropriate amount of refrigerant while simplifying the conditions for determining the amount of refrigerant.

  Thus, in the air conditioner 1, as described above, the liquid temperature constant control is performed in step S2 or step S5, and then the liquid pipe closing control is performed in step S4 or step S7. Liquid refrigerant storage control is performed in which the refrigerant to be condensed is condensed in the outdoor heat exchanger 23 and stored in the upstream portion of the outdoor expansion valve 38 including the outdoor heat exchanger 23. And the state quantity regarding the refrigerant | coolant amount which exists in the upstream of the outdoor expansion valve 38 by the process of above-mentioned step S8, S9 is detected, and it becomes the state quantity regarding the refrigerant | coolant amount which the liquid level detection sensor 39 detected in the refrigerant | coolant amount determination driving | operation. Based on this, it is possible to determine whether or not the amount of refrigerant in the refrigerant circuit 10 is appropriate.

  These processes such as control are performed by an operation control unit that performs the refrigerant amount determination operation, and a control unit 8 that functions as a refrigerant amount determination unit that determines the suitability of the refrigerant amount in the refrigerant circuit 10 (more specifically, the chamber This is performed by the transmission line 8a) connecting the inner control units 47, 57, the outdoor control unit 37, and the control units 37, 47, 57.

  In the present embodiment, by performing liquid temperature constant control (particularly liquid pipe temperature control), a portion of the refrigerant circuit 10 between the use side expansion mechanism including the liquid refrigerant communication pipe 6 and the blocking mechanism is provided. Since a constant amount of refrigerant is always contained, the length of the liquid refrigerant communication pipe 6 constituting the refrigerant circuit 10 is long, and the amount of refrigerant contained in the liquid refrigerant communication pipe 6 by the process of step S4 or step S7. Even when there is a relatively large amount, it is possible to contain an accurate amount of refrigerant in the liquid refrigerant communication pipe 6, so that the refrigerant circuit 10 is upstream of the outdoor expansion valve 38 and the compressor 21. Although the influence on the refrigerant amount in the downstream portion can be suppressed and the state quantity related to the refrigerant amount can be stably detected by the liquid level detection sensor 39, the refrigerant circuit 10 is configured. When the length of the liquid refrigerant communication pipe 6 is short and the amount of refrigerant contained in the liquid refrigerant communication pipe 6 is small by the processing in step S3 or step S6, the refrigerant circuit 10 is upstream of the outdoor expansion valve 38. In addition, since the influence on the refrigerant amount in the downstream portion of the compressor 21 is small, it is not always necessary to perform constant liquid temperature control (particularly, liquid pipe temperature control), and the processing in step S3 or step S6 is omitted. May be.

<Refrigerant leak detection operation mode>
Next, the refrigerant leak detection operation mode will be described.

  The refrigerant leakage detection operation mode is substantially the same as the refrigerant automatic charging operation mode except that it involves a refrigerant charging operation, and only the differences will be described.

  In the present embodiment, the refrigerant leakage detection operation mode is, for example, periodically (such as a time zone in which air conditioning is not required during holidays or midnight), and the refrigerant does not leak to the outside from the refrigerant circuit 10 due to an unexpected cause. This is an operation performed when detecting whether or not.

  In the refrigerant leakage detection operation, the same processing as that in the above-described refrigerant automatic charging operation is performed.

  That is, in the refrigerant circuit 10, the liquid temperature constant control is performed in the cooling operation state or the heating operation state, and after the liquid temperature becomes constant, the indoor expansion valves 41 and 51 and the liquid side closing valve 26 are fully closed, and the liquid pipe The fixed refrigerant amount Y is fixed (see step S1 to step S7). Further, along with the operation of the indoor expansion valves 41 and 51 and the liquid side closing valve 26, the bypass expansion valve 62 is fully opened, the outdoor expansion valve 38 is fully closed, and the cooling operation is continued, thereby the outdoor heat exchanger. The refrigerant quantity determination operation for storing the liquid refrigerant in 23 is performed.

  Here, if the detection liquid level height h by the liquid level detection sensor 39 is maintained unchanged for a predetermined time, the liquid level height h at that time is expressed by the relational expression stored in the memory of the control unit 8. By substituting, the determination liquid refrigerant amount X ′ accumulated from the outdoor expansion valve 38 to the outdoor heat exchanger 23 is calculated. Here, whether or not the refrigerant leaks in the refrigerant circuit 10 is determined based on whether or not the appropriate refrigerant amount Z is obtained by adding the liquid pipe determined refrigerant amount Y to the calculated determination liquid refrigerant amount X ′.

  In addition, after acquiring the data of the liquid level height h without changing the liquid level height h for a predetermined time, the operation of the compressor 21 is immediately stopped. Thereby, the refrigerant leakage detection operation is terminated.

  The determination of refrigerant leakage detection is not limited to the method of calculating the above-described determination liquid refrigerant amount X ′. For example, a reference liquid level height H corresponding to the optimal refrigerant amount is calculated in advance, and this value is calculated. By storing in the memory of the control unit 8, the detected liquid level height h is directly compared with the reference liquid level height H as an index without the need to calculate the determination liquid refrigerant amount X ′. By doing so, refrigerant leakage detection may be performed.

(3) Features of the air conditioner The air conditioner 1 of the present embodiment has the following features.

  In the air-conditioning apparatus 1 of the present embodiment, when the condition on the heating operation state side is satisfied from the cooling / heating determination graph shown in FIG. 6 based on the outside air temperature and the room temperature at that time (that is, below the straight line L) In the case of the conditions of the above-mentioned region), the refrigerant circuit 10 is circulated through portions between the indoor expansion valves 41 and 51 including the liquid refrigerant communication pipe 7 and the outdoor expansion valve 38 (hereinafter referred to as liquid refrigerant pipe portion). The control unit 8 performs control in the heating operation state (liquid temperature constant control in the heating operation state) so that the temperature of the liquid refrigerant to be performed becomes a constant value. Further, from the cooling / heating determination graph shown in FIG. 6 on the basis of the outside air temperature and the room temperature at that time, when the condition is on the cooling operation state side (that is, in the condition of the region above the straight line L), The control unit 8 performs control in the cooling operation state so that the temperature of the liquid refrigerant flowing through the liquid refrigerant pipe portion becomes a constant value (constant liquid temperature control in the cooling operation state).

  By performing this liquid temperature constant control, the inside of the liquid refrigerant pipe portion can be stably sealed with the liquid refrigerant at a constant temperature. Accordingly, the temperature of the refrigerant sent from the outdoor heat exchanger 23 to the indoor expansion valves 41 and 51 through the liquid refrigerant communication pipe 7 is adjusted to be constant, and the amount of refrigerant fixed inside the liquid refrigerant pipe portion is maintained. As a result, the indoor expansion valves 41 and 51 and the outdoor expansion valve 38 are closed to contain the amount of liquid refrigerant fixed to the liquid refrigerant pipe portion (liquid pipe closing control). Then, in a state where the liquid refrigerant is sealed in the liquid refrigerant piping portion, the control units 37, 47 and 57 store the liquid refrigerant in the upstream portion (mainly the outdoor heat exchanger 23) of the outdoor expansion valve 38 in the cooling operation state. The liquid level storage sensor 39 detects the state quantity related to the refrigerant amount of the liquid refrigerant accumulated upstream of the outdoor expansion valve 38, and detects whether the refrigerant quantity in the refrigerant circuit is appropriate based on the state quantity. Is determined by the refrigerant amount determination means.

  In the air conditioner 1 of the present embodiment, the liquid temperature constant control is performed in the heating operation state or the liquid temperature constant control is performed in the cooling operation state according to the ambient conditions such as the outside air temperature and the room temperature. An optimal operating state can be selected when performing a constant liquid temperature control. The optimum operating state mentioned here is an operating state in which the pressure on the high-pressure side can be maintained at a predetermined pressure, and at least the flash state cannot be achieved inside the liquid refrigerant pipe portion. In addition, if the liquid temperature constant control is performed in the cooling operation state when the outside air temperature is low, even when the room temperature is sufficiently high at the start of the liquid temperature constant control, the room temperature is lowered by the cooling during the operation, and the cooling operation is being performed. However, if the liquid temperature constant control is performed in a heating operation state, the room temperature is prevented from being lowered by heating the room, and the liquid temperature constant control is performed in a more stable state. be able to. Therefore, in the present invention, the liquid temperature constant control can be performed in a stable state regardless of the temperature conditions of the outside air temperature and the room temperature, and based on the state quantity related to the refrigerant amount with less error. Whether or not the amount of refrigerant in the refrigerant circuit 10 is appropriate can be determined.

(Second Embodiment)
In the above-described first embodiment and the air conditioner 1 in the modified example, the case where there is one outdoor unit is described as an example, but the present invention is not limited to this, and for example, the present embodiment shown in FIG. Like the air conditioner 101 of the form, a plurality of (in the present embodiment, two) outdoor units 2 may be provided in parallel. Here, the outdoor unit 2 and the indoor units 4 and 5 have the same configurations as the outdoor unit 2 and the indoor units 4 and 5 in the first embodiment described above, and thus description thereof is omitted here.

  In the air conditioning apparatus 101 of the present embodiment, detection by the liquid level detection sensor 39 is individually performed in each outdoor unit 2 in the automatic refrigerant charging operation and the refrigerant leakage detection operation, and the outdoor heat exchanger collected refrigerant amount X is Although it is different in that the determination as to whether or not the refrigerant has accumulated is made with respect to the refrigerant amount in the refrigerant circuit 110 including all the outdoor units 2, basically, the refrigerant circuit 10 in the first embodiment described above This is the same as the determination of the suitability of the refrigerant amount. Moreover, in the air conditioning apparatus 101 of this embodiment, you may apply the structure similar to the modifications 1-3 of the above-mentioned 1st Embodiment.

(Third embodiment)
In the air conditioning apparatuses 1 and 101 in the first and second embodiments described above and the modifications thereof, the case where the present invention is applied to the configuration in which the cooling operation and the heating operation can be switched is described as an example, but the present invention is not limited thereto. For example, like the air conditioner 201 of the present embodiment shown in FIG. 10, for example, a cooling operation is performed for a certain air-conditioned space, and a heating operation is performed for another air-conditioned space. In addition, the present invention may be applied to a configuration capable of simultaneous cooling and heating according to the requirements of indoor air-conditioned spaces in which the indoor units 4 and 5 are installed.

  The air conditioner 201 of the present embodiment mainly includes indoor units 4 and 5 as a plurality of (here, two) use units, an outdoor unit 202 as a heat source unit, and refrigerant communication pipes 6, 7 a, and 7 b. And.

  The outdoor units 4 and 5 are connected to the outdoor unit 202 via the liquid refrigerant communication pipe 6, the intake gas refrigerant communication pipe 7a and the discharge gas refrigerant communication pipe 7b as gas refrigerant communication pipes, and the connection units 204 and 205. The refrigerant circuit 210 is configured with the outdoor unit 202. In addition, since the indoor units 4 and 5 are the same structures as the indoor units 4 and 5 in the above-mentioned 1st Embodiment, description is abbreviate | omitted here.

  The outdoor unit 202 mainly constitutes a part of the refrigerant circuit 210 and includes an outdoor refrigerant circuit 210c. The outdoor refrigerant circuit 210c mainly includes a compressor 21, a three-way switching valve 222, an outdoor heat exchanger 23 as a heat source side heat exchanger, a liquid level detection sensor 39 as a refrigerant detection mechanism, and a second cutoff mechanism. Alternatively, an outdoor expansion valve 38 as a heat source side expansion mechanism, an accumulator 24, a supercooler 25 as a temperature adjustment mechanism, a bypass refrigerant pipe 61 as a cooling source and a communication pipe of the supercooler 25, and a first shut-off mechanism As a liquid side closing valve 26, an intake gas side closing valve 27a, a discharge gas side closing valve 27b, a high / low pressure communication pipe 233, a high pressure shut-off valve 234, and an outdoor fan 28. Here, the other devices and valves other than the three-way switching valve 222, the suction gas side closing valve 27a, the discharge gas side closing valve 27b, the high and low pressure communication pipe 233, and the high pressure cutoff valve 234 are the same as those in the first embodiment. Since it is the structure similar to the apparatus and valves of the outdoor unit 2, the description is omitted.

  The three-way switching valve 222 connects the discharge side of the compressor 21 and the gas side of the outdoor heat exchanger 23 when the outdoor heat exchanger 23 functions as a condenser (hereinafter referred to as a condensing operation state). When the heat exchanger 23 functions as an evaporator (hereinafter referred to as an evaporation operation state), the inside of the outdoor refrigerant circuit 210c is connected so that the suction side of the compressor 21 and the gas side of the outdoor heat exchanger 23 are connected. It is a valve for switching the flow path of the refrigerant. A discharge gas refrigerant communication pipe 7b is connected between the discharge side of the compressor 21 and the three-way switching valve 222 via a discharge gas side closing valve 27b. Thereby, the high-pressure gas refrigerant compressed and discharged in the compressor 21 can be supplied to the indoor units 4 and 5 regardless of the switching operation of the three-way switching valve 222. An intake gas refrigerant communication pipe 7a is connected to the intake side of the compressor 21 via an intake gas side closing valve 27a. As a result, the low-pressure gas refrigerant returning from the indoor units 4 and 5 can be returned to the suction side of the compressor 21 regardless of the switching operation of the three-way switching valve 222. The high / low pressure communication pipe 233 includes a refrigerant pipe connecting a position between the discharge side of the compressor 21 and the three-way switching valve 222 and the discharge gas refrigerant communication pipe 7b, and a suction side of the compressor 21 and a suction gas. This is a refrigerant pipe that communicates with a refrigerant pipe that connects to the refrigerant communication pipe 7a, and has a high-low pressure communication valve 233a that can block the passage of the refrigerant. Accordingly, the intake gas refrigerant communication pipe 7a and the discharge gas refrigerant communication pipe 7b can be brought into communication with each other as necessary. The high-pressure shut-off valve 234 is provided in a refrigerant pipe connecting the position between the discharge side of the compressor 21 and the three-way switching valve 222 and the discharge gas refrigerant communication pipe 7b. The high-pressure gas refrigerant discharged from the machine 21 can be blocked from being sent to the discharge gas refrigerant communication pipe 7b. In the present embodiment, the high-pressure shut-off valve 234 has a high-low pressure communication pipe 233 connected to a refrigerant pipe connecting the position between the discharge side of the compressor 21 and the three-way switching valve 222 and the discharge gas refrigerant communication pipe 7b. It is arranged on the discharge side of the compressor 21 with respect to the position. In the present embodiment, the high / low pressure communication valve 233a and the high pressure cutoff valve 234 are electromagnetic valves. In the present embodiment, the three-way switching valve 222 is used as a mechanism for switching between the condensing operation state and the evaporation operation state. You may use what comprised the solenoid valve.

  Also, the outdoor unit 202 is provided with various sensors and the outdoor control unit 37, and these are also the configurations of the various sensors and the outdoor control unit 37 of the outdoor unit 2 in the first embodiment described above. Since it is the same as that, description is abbreviate | omitted.

  The indoor units 4 and 5 are connected so that the gas side of the indoor heat exchangers 42 and 52 can be switched to the intake gas refrigerant communication pipe 7a and the discharge gas refrigerant communication pipe 7b via the connection units 204 and 205. The connection units 204 and 205 mainly include cooling / heating switching valves 204a and 205a. The cooling / heating switching valves 204a and 205a connect the gas side of the indoor heat exchangers 42 and 52 of the indoor units 4 and 5 and the intake gas refrigerant communication pipe 7a when the indoor units 4 and 5 perform cooling operation ( When the indoor units 4 and 5 perform the heating operation, the gas side of the indoor heat exchangers 42 and 52 of the indoor units 4 and 5 and the discharge gas refrigerant communication pipe 7b are connected. It is a valve that functions as a switching mechanism that switches between a state (hereinafter referred to as a heating operation state). In the present embodiment, as the mechanism for switching between the cooling operation state and the heating operation state, cooling / heating switching valves 204a and 205a including three-way switching valves are used, but the present invention is not limited to this. You may use what consists of a four-way switching valve, a some electromagnetic valve, etc.

  With such a configuration of the air conditioner 201, the indoor units 4 and 5 can perform a so-called simultaneous cooling and heating operation, for example, a heating operation of the indoor unit 5 while the indoor unit 4 is performing a cooling operation. It has become.

  In the air conditioning apparatus 201 that can be operated simultaneously with cooling and heating, the three-way switching valve 222 is set in a condensing operation state, the outdoor heat exchanger 23 is functioned as a refrigerant condenser, and the cooling and heating switching valves 204a and 205a are set in a cooling operation state. Thus, by causing the indoor heat exchangers 42 and 52 to function as a refrigerant evaporator, it is possible to perform the refrigerant amount determination operation and determination of the appropriateness of the refrigerant amount in the same manner as the air conditioner 1 in the first embodiment described above.

  However, since the air conditioner 201 of the present embodiment has the intake gas refrigerant communication pipe 7a and the discharge gas refrigerant communication pipe 7b as the gas refrigerant communication pipe 7, the air refrigerant apparatus 201 is high in the cooling operation in the normal operation mode. By making the low-pressure communication valve 233a fully closed and the high-pressure shut-off valve 234 fully open, the intake gas refrigerant communication pipe 7a and the discharge gas refrigerant communication pipe 7b are not in communication, and the compressor 21 When the high-pressure gas refrigerant discharged from the refrigerant can be sent to the discharge gas refrigerant communication pipe 7b, the high-pressure gas refrigerant accumulated in the discharge gas refrigerant communication pipe 7b is condensed in the outdoor heat exchanger 23. It becomes impossible to accumulate in the upstream portion of the outdoor expansion valve 38 including the outdoor heat exchanger 23, which adversely affects the determination accuracy of the refrigerant amount in the refrigerant circuit 10. Therefore, in the refrigerant amount determination operation, the intake gas refrigerant communication pipe 7a and the discharge gas refrigerant communication pipe are set by fully closing the high / low pressure communication valve 233a and fully opening the high pressure shut-off valve 234. 7 b is communicated, and the high-pressure gas refrigerant discharged from the compressor 21 is blocked from being sent to the discharge gas refrigerant communication pipe 7 b. As a result, the pressure of the refrigerant in the discharge gas refrigerant communication pipe 7b becomes the same as the pressure of the refrigerant in the suction gas refrigerant communication pipe 7a, and no refrigerant accumulates in the discharge gas refrigerant communication pipe 7b. The high-pressure gas refrigerant accumulated in the communication pipe 7b can be condensed in the outdoor heat exchanger 23 and accumulated in the upstream portion of the outdoor expansion valve 38 including the outdoor heat exchanger 23. This makes it difficult to adversely affect the determination accuracy of the refrigerant amount.

  As described above, in the air conditioner 201 of the present embodiment, in the refrigerant amount determination operation, the intake gas refrigerant communication pipe is set by fully closing the high / low pressure communication valve 233a and fully opening the high pressure shut-off valve 234. 7a and the discharge gas refrigerant communication pipe 7b are in communication with each other, and the operation of blocking the high-pressure gas refrigerant discharged from the compressor 21 from being sent to the discharge gas refrigerant communication pipe 7b is performed. Although it is different from the air conditioner 1 in FIG. 1, it is basically the same as the determination of the suitability of the refrigerant amount in the refrigerant circuit 10 in the first embodiment. Moreover, in the air conditioning apparatus 201 of this embodiment, you may apply the structure similar to the modification 1-3 of the above-mentioned 1st Embodiment, and is like the air conditioning apparatus 101 of 2nd Embodiment. Further, a configuration in which a plurality of outdoor units 202 are connected may be employed.

(Other embodiments)
As mentioned above, although embodiment of this invention and its modification were demonstrated based on drawing, specific structure is not restricted to these embodiment and its modification, It changes in the range which does not deviate from the summary of invention. Is possible.

  For example, the present invention is applied not to the air conditioners 1 and 101 that can be switched between the cooling operation and the heating operation or the air conditioner 201 that can simultaneously operate the cooling operation and the heating operation, but also to an air conditioner dedicated to the cooling operation. Is possible.

  The air conditioner and the refrigerant amount determination method according to the present invention have the effect that it is possible to determine the suitability of the refrigerant amount in the refrigerant circuit based on the state quantity related to the refrigerant amount with less error, In the air conditioner and the refrigerant amount determination operation for determining whether or not the refrigerant amount is appropriate, it is useful as an air conditioner and a refrigerant amount determination operation for performing optimal control for the conditions at that time.

It is a schematic structure figure of the air harmony device concerning a 1st embodiment of the present invention. It is the schematic of an outdoor heat exchanger. It is a control block diagram of an air conditioning apparatus. It is a schematic diagram which shows the state of the refrigerant | coolant which flows through the inside of the refrigerant circuit in air_conditionaing | cooling operation. It is a flowchart of a refrigerant | coolant amount determination driving | operation. 6 is a cooling / heating determination graph for determining an operation state when performing liquid temperature constant control. It is a schematic diagram which shows the state of the refrigerant | coolant which flows through the refrigerant circuit in a refrigerant | coolant amount determination driving | operation. It is the figure which showed typically the inside of the heat exchanger main body of FIG. 2, and a header, Comprising: It is a figure which shows a mode that a refrigerant | coolant accumulates in an outdoor heat exchanger in refrigerant | coolant amount determination driving | operation. It is a schematic block diagram of the air conditioning apparatus concerning 2nd Embodiment. It is a schematic block diagram of the air conditioning apparatus concerning 3rd Embodiment.

Explanation of symbols

1, 101, 201 Air conditioner 2, 202 Outdoor unit (heat source unit)
4, 5 Indoor unit (Usage unit)
6 Liquid refrigerant communication pipe 7, 7a, 7b Gas refrigerant communication pipe 10, 110, 210 Refrigerant circuit 21 Compressor 22 Four-way switching valve (switching mechanism)
23 Outdoor heat exchanger (heat source side heat exchanger)
38 Outdoor expansion valve (second shut-off mechanism)
39 Liquid level detection sensor (refrigerant detection mechanism)
41, 51 Indoor expansion valve (use side expansion mechanism)
42, 52 Indoor heat exchanger (use side heat exchanger)

Claims (4)

Use having heat source unit (2, 202) having compressor (21) and heat source side heat exchanger (23), use side expansion mechanism (41, 51) and use side heat exchanger (42, 52) A refrigerant circuit (10, 110, 210) including a unit (4, 5), a liquid refrigerant communication pipe (6) and a gas refrigerant communication pipe (7, 7a, 7b) connecting the heat source unit and the utilization unit. )When,
Cooling operation is performed so that the heat source side heat exchanger functions as a refrigerant condenser to be compressed in the compressor, and the use side heat exchanger functions as an evaporator for refrigerant condensed in the heat source side heat exchanger. Cooling operation state, the use side heat exchanger as a refrigerant condenser to be compressed in the compressor, and the heat source side heat exchanger as a refrigerant evaporator to be condensed in the use side heat exchanger. A switching mechanism (22) capable of switching between a heating operation state for causing a heating operation to function;
A shut-off mechanism (38) that is arranged on the downstream side of the heat source side heat exchanger and the upstream side of the liquid refrigerant communication pipe in the flow direction of the refrigerant in the cooling operation, and can block the passage of the refrigerant;
A refrigerant detection mechanism (39) that is arranged upstream of the shut-off mechanism in the refrigerant flow direction in the cooling operation, and detects a state quantity related to the refrigerant amount existing on the upstream side of the shut-off mechanism;
In the heating operation state, the liquid temperature constant control is performed so that the refrigerant temperature in the liquid refrigerant pipe portion between the use-side expansion mechanism including the liquid refrigerant communication pipe in the refrigerant circuit and the shut-off mechanism becomes a constant value. Is performed, the liquid pipe closing control for closing the shut-off mechanism and the use-side expansion mechanism is performed, and then the liquid refrigerant storage control for storing the liquid refrigerant in the upstream portion of the shut-off mechanism is performed in the cooling operation. Operation control means to be performed in the state;
Refrigerant amount determination means for determining the suitability of the refrigerant amount in the refrigerant circuit based on the state amount related to the refrigerant amount detected by the refrigerant detection mechanism in the liquid refrigerant storage control;
An air conditioner (1, 101, 201) comprising: The operation control means includes
When the predetermined condition is satisfied, after the liquid temperature constant control is performed in the heating operation state, the liquid pipe closing control is performed, and thereafter, the liquid refrigerant storage control is performed in the cooling operation state,
When the predetermined condition is not satisfied, after the liquid temperature constant control is performed in the cooling operation state, the liquid pipe closing control is performed, and thereafter, the liquid refrigerant storage control is performed in the cooling operation state.
The air conditioner (1, 101, 201) according to claim 1. The predetermined condition is that the indoor temperature in the room where the utilization unit is installed is lower than a first predetermined temperature and / or the outdoor temperature outside the room where the heat source unit is installed is lower than a second predetermined temperature. Is,
The air conditioning apparatus (1, 101, 201) according to claim 2. Use having heat source unit (2, 202) having compressor (21) and heat source side heat exchanger (23), use side expansion mechanism (41, 51) and use side heat exchanger (42, 52) A refrigerant circuit (10, 110, 210) including a unit (4, 5), a liquid refrigerant communication pipe (6) and a gas refrigerant communication pipe (7, 7a, 7b) connecting the heat source unit and the utilization unit. ), And the heat source side heat exchanger functions as a refrigerant condenser compressed in the compressor, and the use side heat exchanger functions as a refrigerant evaporator condensed in the heat source side heat exchanger. Cooling operation state in which cooling operation is performed, the use side heat exchanger as a refrigerant condenser compressed in the compressor, and the heat source side heat exchanger as a refrigerant condensed in the use side heat exchanger With an evaporator In an air conditioner (1, 101, 201) having a switching mechanism (22) capable of switching between a heating operation state for causing a heating operation to function and determining whether or not the refrigerant amount in the refrigerant circuit is appropriate. A refrigerant amount determination method,
A shut-off mechanism (38) that is arranged on the downstream side of the heat source side heat exchanger and the upstream side of the liquid refrigerant communication pipe in the flow direction of the refrigerant in the refrigerant circuit during the cooling operation and can shut off the refrigerant passage. ) And a liquid temperature constant control for controlling the refrigerant temperature of the liquid refrigerant pipe portion between the utilization side expansion mechanism to be a constant value in the heating operation state,
Perform liquid tube closing control to close the blocking mechanism and the user-side expansion mechanism,
Liquid refrigerant storage control for storing liquid refrigerant in the upstream portion of the shut-off mechanism is performed in the cooling operation state,
A refrigerant detection mechanism (39) that is arranged upstream of the blocking mechanism and detects a state quantity related to the amount of refrigerant existing upstream of the blocking mechanism in the flow direction of the refrigerant in the refrigerant circuit during the cooling operation. ) To detect a state quantity related to the refrigerant quantity existing upstream of the shut-off mechanism,
Based on a state quantity related to the refrigerant quantity detected by the refrigerant detection mechanism in the liquid refrigerant storage control, the suitability of the refrigerant quantity in the refrigerant circuit is determined.
Refrigerant amount determination method.

Images