JP2015224828A - Refrigeration device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect overcharge without erroneous detection in a refrigeration device including a refrigerant circuit constituted by connecting a plurality of heat source unit having receivers and a utilization unit.SOLUTION: Receiver liquid level detection tubes (43a, 43b) are respectively connected to receivers (28a, 28b), and the receiver liquid level detection tubes (43a, 43b) are respectively provided with vent valves (42a, 42b). Here, drift detection state quantities as a state quantity for detecting presence or absence of the drift of a refrigerant between heat source units (2a, 2b), are compared between the heat source units (2a, 2b), and when the relationship between the drift detection state quantities, satisfies a non-drift state, the vent valves (42a, 42b) are opened, and the whether the liquid level in the receivers (28a, 28b) reach prescribed positions or not, is detected, to determine whether the refrigerant is supercharged to the refrigerant circuit (10) or not.

Description

  The present invention relates to a refrigeration apparatus, in particular, a refrigerant circuit configured by connecting a plurality of heat source units having a compressor, a heat source side heat exchanger, and a receiver, and a utilization unit having a utilization side heat exchanger. The present invention relates to a refrigeration apparatus provided.

  Conventionally, as shown in Patent Document 1 (Japanese Patent Laid-Open No. 2006-292212), a heat source unit having a compressor, a heat source side heat exchanger, and a receiver, and a utilization unit having a utilization side heat exchanger are connected. There is an air conditioning apparatus (refrigeration apparatus) provided with a refrigerant circuit constituted by the above. In this refrigeration apparatus, a receiver liquid level detection tube for detecting whether or not the receiver has reached a predetermined liquid level is connected to the receiver.

  In the refrigeration apparatus, it is conceivable to determine whether or not the refrigerant is overfilled in the refrigerant circuit using the receiver liquid level detection tube. For example, a receiver liquid level detection tube is connected to a liquid level position where it can be determined that the refrigerant is overfilled, and this liquid level position is set as a predetermined liquid level of the receiver. When the receiver reaches the predetermined liquid level by the receiver liquid level detection tube when performing the overfill detection operation that is a refrigeration cycle operation for determining whether or not the refrigerant is overfilled in the refrigerant circuit. It is determined that the refrigerant is overfilled.

  However, when a configuration in which a plurality of heat source units are connected as a refrigeration apparatus, there is a possibility that the refrigerant drifts between the heat source units. If the refrigerant is biased to any one of the heat source units, a specified amount of refrigerant is placed in the refrigerant circuit. Even though the refrigerant is not overfilled, it may be determined that there is a heat source unit having a receiver reaching the predetermined liquid level, and the refrigerant is overfilled. There is a risk of false detection.

  An object of the present invention is to enable overfilling detection without erroneous detection in a refrigeration apparatus including a refrigerant circuit configured by connecting a plurality of heat source units having a receiver and a utilization unit.

  A refrigeration apparatus according to a first aspect is a refrigerant circuit configured by connecting a plurality of heat source units having a compressor, a heat source side heat exchanger, and a receiver, and a utilization unit having a utilization side heat exchanger. Is included. Each receiver is connected to a receiver liquid level detection tube for detecting whether the liquid level in the receiver has reached a predetermined position, and each receiver liquid level detection tube is provided with a degassing valve that can be opened and closed. Yes. In this case, an overfill detection operation that is a refrigeration cycle operation for determining whether or not the refrigerant is overfilled in the refrigerant circuit is performed, and during the overfill detection operation, there is presence or absence of refrigerant drift between the plurality of heat source units. The drift detection state quantity, which is the state quantity for detecting the flow rate, is compared between multiple heat source units.If the relationship between the drift detection state quantities satisfies the non-flow condition, the vent valve is opened and the liquid in the receiver is opened. By detecting whether or not the surface has reached a predetermined position, it is determined whether or not the refrigerant is overfilled in the refrigerant circuit.

  Here, in the configuration in which a plurality of heat source units are connected as described above, when overfilling detection is performed by the receiver liquid level detection tube, the timing for performing overfilling detection by opening the gas vent valve of the receiver liquid level detection tube is set. This is done after satisfying a non-drift condition where it can be considered that no refrigerant drift has occurred between the heat source units.

  Thereby, here, overfill detection by the receiver liquid level detection tube can be performed without erroneous detection in a state in which no refrigerant drift occurs between the heat source units.

  In the refrigeration apparatus according to the second aspect, in the refrigeration apparatus according to the first aspect, the overfill detection operation causes the use side heat exchanger to function as an evaporator of the refrigerant, and each heat source side heat exchanger is replaced with the refrigerant. This is an operation to function as a heat radiator.

  Here, as described above, by adopting an operation in which the heat source side heat exchanger of each heat source unit functions as a refrigerant radiator as an overfill detection operation, a large amount of liquid refrigerant is used as a heat source during the overfill detection operation. The state where the liquid refrigerant is accumulated in the side heat exchanger is created so that the liquid refrigerant does not accumulate as much as possible in the receiver of each heat source unit.

  Thereby, here, when overfilling does not occur and when the refrigerant flow between the plurality of heat source units does not occur, the liquid level of the receiver of each heat source unit is higher than the predetermined liquid level. Maintain stable operation at a low liquid level position, and make sure that the liquid level of the receiver clearly changes when refrigerant drift occurs between multiple heat source units or when overfilling occurs. be able to.

  The refrigeration apparatus according to the third aspect is the refrigeration apparatus according to the second aspect, wherein the drift detection state quantity is the degree of refrigerant subcooling at the outlet of each heat source side heat exchanger that functions as a refrigerant radiator, or This is a state quantity equivalent to the degree of supercooling.

  Here, as described above, the degree of subcooling of the refrigerant at the outlet of each heat source side heat exchanger that changes according to the amount of liquid refrigerant accumulated in the heat source side heat exchanger of each heat source unit, or the degree of subcooling The state quantity equivalent to is the drift detection state quantity.

  Thus, here, by comparing the amount of liquid refrigerant that accumulates in the heat source side heat exchanger of each heat source unit that significantly affects the amount of liquid refrigerant that accumulates in the receiver of each heat source unit during overfill detection operation. Therefore, it is possible to accurately determine whether or not the non-drift condition is satisfied.

  The refrigeration apparatus according to the fourth aspect is the refrigeration apparatus according to the second or third aspect, wherein the refrigeration apparatus includes a liquid refrigerant communication tube that satisfies the non-biased condition and connects the plurality of heat source units and the utilization unit in the refrigerant circuit. The degassing valve is opened when a liquid filling condition in which a portion between the receiver and the use-side heat exchanger is filled with the liquid refrigerant is satisfied.

  Here, as described above, during the overfill detection operation, the liquid pipe portion in which a large amount of liquid refrigerant is accumulated in the same manner as the heat source side heat exchanger (the portion between the receiver including the liquid refrigerant communication pipe and the use side heat exchanger) ) In a state where the liquid refrigerant is surely accumulated, and a state where the liquid refrigerant does not accumulate as much as possible in the receiver of each heat source unit is created.

  Thereby, here, when overfilling does not occur and when the refrigerant flow between the plurality of heat source units does not occur, the liquid level of the receiver of each heat source unit is higher than the predetermined liquid level. Maintain stable operation at a low liquid level position, and make sure that the liquid level of the receiver clearly changes when refrigerant drift occurs between multiple heat source units or when overfilling occurs. be able to.

  As described above, according to the present invention, the following effects can be obtained.

  In the refrigeration apparatus according to the first aspect, overfilling detection by the receiver liquid level detection tube can be performed without erroneous detection in a state where refrigerant flow does not occur between the heat source units.

  In the refrigeration apparatus according to the second aspect, the liquid level of the receiver of each heat source unit is predetermined when there is no overfilling and when there is no refrigerant flow between the plurality of heat source units. Keeping a stable operating condition at a liquid level lower than the liquid level, and if the refrigerant drifts between multiple heat source units or overfill occurs, the liquid level of the receiver clearly changes. Can appear.

  In the refrigeration apparatus according to the third aspect, the amount of liquid refrigerant that accumulates in the heat source side heat exchanger of each heat source unit that significantly affects the amount of liquid refrigerant that accumulates in the receiver of each heat source unit during overfill detection operation. By comparing, it can be accurately determined whether the non-drift condition is satisfied.

  In the refrigeration apparatus according to the fourth aspect, the liquid level of the receiver of each heat source unit is predetermined when there is no overfilling and when there is no refrigerant flow between the plurality of heat source units. Keeping a stable operating condition at a liquid level lower than the liquid level, and if the refrigerant drifts between multiple heat source units or overfill occurs, the liquid level of the receiver clearly changes. Can appear.

1 is a schematic configuration diagram of a cooling and heating simultaneous operation type air conditioner as one embodiment of a refrigeration apparatus according to the present invention (only one heat source unit is shown in detail). It is a schematic block diagram (only a heat-source unit is shown) of the heating-and-cooling simultaneous operation type air conditioning apparatus as one Embodiment of the freezing apparatus concerning this invention. It is the schematic which shows the structure of a receiver and its periphery. It is a figure which shows the operation | movement (flow of a refrigerant | coolant) in the cooling operation of normal operation mode. It is a figure which shows the operation | movement (flow of a refrigerant | coolant) in the heating operation of normal operation mode. It is a figure which shows the operation | movement (flow of a refrigerant | coolant) in the heating / cooling simultaneous operation (evaporation load main body) of normal operation mode. It is a figure which shows the operation | movement (flow of a refrigerant | coolant) in the heating / cooling simultaneous driving | operation (heat dissipation load main body) of normal operation mode. It is a flowchart of the overfilling detection operation in the trial operation mode. It is a figure which shows the operation | movement (flow of a refrigerant | coolant) in the overfilling detection driving | operation of test operation mode.

  Hereinafter, an embodiment of a refrigeration apparatus according to the present invention will be described based on the drawings. In addition, the specific structure of the freezing apparatus concerning this invention is not restricted to the following embodiment and its modification, It can change in the range which does not deviate from the summary of invention.

(1) Configuration of refrigeration apparatus (cooling / heating simultaneous operation type air conditioner) FIG. 1 is a schematic configuration diagram (only a heat source unit 2a) of a cooling / heating simultaneous operation type air conditioning apparatus 1 as an embodiment of a refrigeration apparatus according to the present invention. (Shown in detail). FIG. 2 is a schematic configuration diagram (only the heat source units 2a and 2b are shown) of the cooling and heating simultaneous operation type air conditioner as one embodiment of the refrigeration apparatus according to the present invention. The cooling and heating simultaneous operation type 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 cooling and heating simultaneous operation type air conditioner 1 mainly includes a plurality (here, two) of heat source units 2a and 2b, a plurality (here, four) of usage units 3a, 3b, 3c, and 3d, and each usage. The connection units 4a, 4b, 4c and 4d connected to the units 3a, 3b, 3c and 3d, and the heat source units 2a and 2b and the utilization units 3a, 3b, 3c and 3d via the connection units 4a, 4b, 4c and 4d The refrigerant communication pipes 7, 8, and 9 are connected to each other. That is, the vapor compression refrigerant circuit 10 of the cooling and heating simultaneous operation type air conditioner 1 includes heat source units 2a and 2b, utilization units 3a, 3b, 3c, and 3d, connection units 4a, 4b, 4c, and 4d, and refrigerant. The communication pipes 7, 8, and 9 are connected to each other. In the cooling / heating simultaneous operation type air conditioner 1, each of the use units 3a, 3b, 3c, and 3d can individually perform the cooling operation or the heating operation, and the cooling operation is performed from the use unit that performs the heating operation. Heat is recovered between the utilization units by sending the refrigerant to the utilization unit to be performed (here, simultaneous cooling / heating operation in which the cooling operation and the heating operation are performed simultaneously) is possible. Moreover, in the cooling / heating simultaneous operation type air conditioner 1, the heat of the heat source units 2a, 2b is determined according to the heat load of the plurality of utilization units 3a, 3b, 3c, 3d in consideration of the heat recovery (simultaneous cooling / heating operation). It is configured to balance the load.

<Usage unit>
The use units 3a, 3b, 3c, and 3d are installed by being embedded or suspended in a ceiling of a room such as a building, or by hanging on a wall surface of the room. The utilization units 3a, 3b, 3c, and 3d are connected to the heat source units 2a and 2b via the refrigerant communication tubes 7, 8, and 9 and the connection units 4a, 4b, 4c, and 4d. It is composed.

  Next, the configuration of the usage units 3a, 3b, 3c, and 3d will be described. Since the usage unit 3a and the usage units 3b, 3c, and 3d have the same configuration, only the configuration of the usage unit 3a will be described here, and the configuration of the usage units 3b, 3c, and 3d will be described respectively. Instead of the subscript “a” indicating the respective parts of 3a, the subscript “b”, “c” or “d” is attached, and the description of each part is omitted.

  The usage unit 3a mainly constitutes a part of the refrigerant circuit 10, and includes usage-side refrigerant circuits 13a (in the usage units 3b, 3c, and 3d, usage-side refrigerant circuits 13b, 13c, and 13d, respectively). Yes. The utilization side refrigerant circuit 13a mainly has a utilization side flow rate adjustment valve 51a and a utilization side heat exchanger 52a.

  The usage-side flow rate adjustment valve 51a is an electric expansion valve that can adjust the opening degree connected to the liquid side of the usage-side heat exchanger 52a in order to adjust the flow rate of the refrigerant flowing through the usage-side heat exchanger 52a. is there.

  The use-side heat exchanger 52a is a device for performing heat exchange between the refrigerant and the room air, and includes, for example, a fin-and-tube heat exchanger configured by a large number of heat transfer tubes and fins. Here, the utilization unit 3a has an indoor fan 53a for sucking indoor air into the unit and exchanging heat, and then supplying the indoor air as supply air to the indoor unit 53a. It is possible to exchange heat with the refrigerant flowing through The indoor fan 53a is driven by the indoor fan motor 54a.

  In addition, the usage unit 3a includes a usage-side control unit 50a that controls the operations of the units 51a and 54a constituting the usage unit 3a. The use-side control unit 50a includes a microcomputer and a memory provided for controlling the use unit 3a, and exchanges control signals and the like with a remote controller (not shown). Control signals and the like can be exchanged with the heat source units 2a and 2b.

<Heat source unit>
The heat source units 2a and 2b are installed on the rooftop of a building or the like, and are connected to the usage units 3a, 3b, 3c, and 3d via the refrigerant communication tubes 7, 8, and 9, and the usage units 3a, 3b, The refrigerant circuit 10 is comprised between 3c and 3d.

  Next, the configuration of the heat source units 2a and 2b will be described. In addition, since the heat source unit 2a and the heat source unit 2b have the same configuration, only the configuration of the heat source unit 2a will be described here, and the configuration of the heat source unit 2b will be denoted by the reference numerals indicating the respective parts of the heat source unit 2a. Instead of the subscript “a”, the subscript “b” is added, and description of each part is omitted.

  The heat source unit 2a mainly constitutes a part of the refrigerant circuit 10 and has a heat source side refrigerant circuit 12a (in the heat source unit 2b, the heat source side refrigerant circuit 12b). The heat source side refrigerant circuit 12a mainly includes a compressor 21a, a plurality (here, two) of heat exchange switching mechanisms 22a and 23a, and two heat source side heat exchangers 24a and 25a as main heat source side heat exchangers. And a precooling heat exchanger 35a, a heat source side heat exchanger, a refrigerant cooler 36a, heat source side flow control valves 26a and 27a corresponding to the two heat source side heat exchangers 24a and 25a, and a precooling heat exchanger 35a. And a refrigerant cooling side flow rate adjustment valve 37a corresponding to the refrigerant cooler 36a, a receiver 28a, a bridge circuit 29a, a high / low pressure switching mechanism 30a, a liquid side closing valve 31a, a high / low pressure gas side closing valve 32a, a low pressure And a gas side closing valve 33a.

  Here, the compressor 21a is a device for compressing the refrigerant, and includes, for example, a scroll type positive displacement compressor capable of changing the operation capacity by inverter-controlling the compressor motor 21aa.

  The first heat exchange switching mechanism 22a uses the compressor 21a when the first heat source side heat exchanger 24a as the main heat source side heat exchanger functions as a refrigerant radiator (hereinafter referred to as "heat dissipation operation state"). And the gas side of the first heat source side heat exchanger 24a are connected (see the solid line of the first heat exchange switching mechanism 22a in FIGS. 1 and 2), and the first heat source side heat exchanger 24a is connected to the refrigerant When functioning as an evaporator (hereinafter referred to as “evaporation operation state”), the suction side of the compressor 21a and the gas side of the first heat source side heat exchanger 24a are connected (see FIGS. 1 and 2). This is a device capable of switching the refrigerant flow path in the heat source side refrigerant circuit 12a, for example, a four-way switching valve. Further, the second heat exchange switching mechanism 23a compresses when the second heat source side heat exchanger 25a as the main heat source side heat exchanger functions as a refrigerant radiator (hereinafter referred to as "heat dissipation operation state"). The discharge side of the machine 21a and the gas side of the second heat source side heat exchanger 25a are connected (see the solid line of the second heat exchange switching mechanism 23a in FIGS. 1 and 2), and the second heat source side heat exchanger 25a is connected. When functioning as a refrigerant evaporator (hereinafter referred to as “evaporation operation state”), the suction side of the compressor 21a and the gas side of the second heat source side heat exchanger 25a are connected (FIGS. 1 and 3). 2 is a device capable of switching the refrigerant flow path in the heat source side refrigerant circuit 12a, for example, a four-way switching valve. Then, by changing the switching state of the first heat exchange switching mechanism 22a and the second heat exchange switching mechanism 23a, the first heat source side heat exchanger 24a and the second heat source side heat exchanger 25a individually evaporate the refrigerant. Switching to function as a heat sink or a radiator is possible.

  The first heat source side heat exchanger 24a as the main heat source side heat exchanger is a device for performing heat exchange between the refrigerant and the outdoor air, and includes, for example, a fin-and- It consists of a tube heat exchanger. As for the 1st heat source side heat exchanger 24a, the gas side is connected to the 1st heat exchange switching mechanism 22a, and the liquid side is connected to the 1st heat source side flow control valve 26a. The second heat source side heat exchanger 25a as the main heat source side heat exchanger is a device for performing heat exchange between the refrigerant and the outdoor air, and includes, for example, fins and fins configured by a large number of heat transfer tubes and fins. It consists of an and tube type heat exchanger. The gas side of the second heat source side heat exchanger 25a is connected to the second heat exchange switching mechanism 23a, and the liquid side thereof is connected to the second heat source side flow rate adjustment valve 27a.

  The pre-cooling heat exchanger 35a is a device for performing heat exchange between the refrigerant and the outdoor air, and includes, for example, a fin-and-tube heat exchanger configured by a large number of heat transfer tubes and fins. The pre-cooling heat exchanger 35a constitutes a part of the heat source side heat exchanger (that is, a part of the heat source side heat exchanger excluding the heat source side heat exchangers 24a and 25a as the main heat source side heat exchanger). The high-pressure gas refrigerant discharged from the compressor 21a is always provided in the heat source side refrigerant circuit 12a. Specifically, the pre-cooling heat exchanger 35a is different from the heat source side heat exchangers 24a and 25a as main heat source side heat exchangers, and is used as a refrigerant evaporator or radiator such as the heat exchange switching mechanisms 22a and 23a. The gas side is connected to the discharge side of the compressor 21a without using a mechanism for enabling switching to function. That is, unlike the heat source side heat exchangers 24a and 25a as the main heat source side heat exchanger, the precooling heat exchanger 35a always functions as a refrigerant radiator.

  Here, the 1st heat source side heat exchanger 24a, the 2nd heat source side heat exchanger 25a, and the pre-cooling heat exchanger 35a are comprised as an integrated heat source side heat exchanger. The heat source unit 2a has an outdoor fan 34a for sucking outdoor air into the unit, exchanging heat, and then discharging the air outside the unit. The outdoor air and heat source side heat exchangers 24a, 25a, It is possible to exchange heat with the refrigerant flowing through 35a. The outdoor fan 34a is driven by an outdoor fan motor 34aa capable of rotating speed control.

  The refrigerant cooler 36a is a device that cools the electrical component 20aa by exchanging heat between the refrigerant radiated in the precooling heat exchanger 35a and the electrical component 20aa, and is a liquid side of the precooling heat exchanger 35a, that is, precooling heat. It is connected to the downstream side of the exchanger 35a. The refrigerant cooler 36a is configured, for example, by bringing a metal member in which a refrigerant flow path is formed into contact with the electrical component 20aa. Here, the electrical component 20aa is an electrical component for controlling each part constituting the heat source unit 2a, and constitutes a heat source side control part 20a described later. The electrical component 20aa that needs to be cooled by the refrigerant cooler 36a includes high heat generating electrical components such as a power element and a reactor that constitute an inverter for controlling the compressor motor 21aa. Such a high heat generating electrical component tends to generate a larger amount of heat as the operating capacity of the compressor 21a increases. 1 and 2, the electrical component 20aa is illustrated separately from the heat source side control unit 20a, but this is for the sake of convenience for explaining the function of the refrigerant cooler 36a.

  The first heat source side flow rate adjustment valve 26a is configured to adjust the opening degree connected to the liquid side of the first heat source side heat exchanger 24a in order to adjust the flow rate of the refrigerant flowing through the first heat source side heat exchanger 24a. It is a possible electric expansion valve. The second heat source side flow rate adjustment valve 27a is connected to the liquid side of the second heat source side heat exchanger 25a in order to adjust the flow rate of the refrigerant flowing through the second heat source side heat exchanger 25a. It is an electric expansion valve that can be adjusted. That is, the heat source side heat exchangers 24a, 25a, 35a are arranged on the liquid side of the heat source side heat exchangers 24a, 25a as main heat source side heat exchangers, which are parts excluding the precooling heat exchanger 35a. Heat source side flow rate adjusting valves 26a, 27a for adjusting the flow rate of the refrigerant flowing through the exchangers 24a, 25a are connected.

  The refrigerant cooling side flow rate adjustment valve 37a is an electric motor capable of adjusting the opening degree connected to the downstream side of the refrigerant cooler 36a in order to adjust the flow rate of the refrigerant flowing through the precooling heat exchanger 35a and the refrigerant cooler 36a. It is an expansion valve. The heat source side heat exchangers 24a and 25a as the main heat source side heat exchangers are provided downstream of the heat source side flow rate adjusting valves 26a and 27a when functioning as the refrigerant radiator, that is, the first heat source side heat exchanger. The second heat source side flow rate adjustment when the second heat source side heat exchanger 25a functions as a refrigerant radiator downstream of the first heat source side flow rate adjustment valve 26a when the 24a functions as a refrigerant radiator The outlet of the refrigerant cooling side flow rate adjustment valve 37a is connected to the downstream side of the valve 27a. Here, the outlet of the refrigerant cooling side flow rate adjustment valve 37a is connected to join the outlet pipe 28b of the receiver 28a.

  The receiver 28a is a container for temporarily storing the refrigerant flowing between the heat source side heat exchangers 24a and 25a and the use side refrigerant circuits 13a, 13b, 13c, and 13d. A receiver inlet pipe 28aa is provided in the upper part of the receiver 28a, and a receiver outlet pipe 28ba is provided in the lower part of the receiver 28a. The receiver inlet pipe 28aa is provided with a receiver inlet on / off valve 28ca that can be controlled to open and close. The inlet pipe 28aa and the outlet pipe 28ba of the receiver 28a are connected between the heat source side heat exchangers 24a and 25a and the liquid side closing valve 31a via the bridge circuit 29a.

  A receiver degassing pipe 41a is connected to the receiver 28a. The receiver gas vent pipe 41a is provided separately from the receiver inlet pipe 28aa so as to extract the refrigerant from the upper part of the receiver 28a, and connects the upper part of the receiver 28a and the suction side of the compressor 21a. The receiver degassing pipe 41a is provided with a degassing flow rate adjusting valve 42a as a degassing valve in order to adjust the flow rate of the refrigerant degassed from the receiver 28a. Here, the degassing side flow rate adjustment valve 42a is an electric expansion valve capable of adjusting the opening degree.

  Further, as shown in FIG. 3, the receiver 28a has a receiver liquid for detecting whether the liquid level in the receiver 28a reaches a predetermined position L1 below the position where the receiver degassing pipe 41 is connected. A surface detection tube 43a is connected. Here, the receiver liquid level detection tube 43a is provided so as to extract the refrigerant from a portion in the vicinity of the middle in the vertical direction of the receiver 28a. Further, the liquid level position L1 corresponds to a liquid level position at which it can be determined that overfilling of the refrigerant has occurred in the overfill determination described later. The receiver liquid level detection pipe 43a merges with the receiver degassing pipe 41a via the capillary tube 43aa, and the downstream part from the merging part including the degassing side flow rate adjustment valve 42a is the receiver degassing pipe 41a. It is combined with. Here, the receiver liquid level detection pipe 43a is provided so as to join the upstream portion of the receiver gas vent pipe 41a where the gas vent side flow rate adjustment valve 42a is provided. Further, the receiver degassing pipe 41a is provided with a refrigerant heater 44a for heating the refrigerant flowing through the receiver degassing pipe 41a on the downstream side of the position where the receiver liquid level detection pipe 43 joins. Here, the refrigerant heater 44a is a heat exchanger that heats the refrigerant flowing through the receiver degassing pipe 41a using the high-pressure gas refrigerant discharged from the compressor 21 as a heating source. The refrigerant heater 44a branches a part of the high-pressure gas refrigerant discharged from the compressor 21a and sends it to the pre-cooling heat exchanger 35a which is a part of the heat source side heat exchangers 24a, 25a, 35a. And a pipe heat exchanger, a double pipe heat exchanger, and the like configured by bringing the receiver gas vent pipe 41a into contact with each other. That is, the refrigerant heater 44a is connected to the upstream side of the precooling heat exchanger 35a through which the high-pressure gas refrigerant discharged from the compressor 21a always flows. During the refrigeration cycle operation, a part of the high-pressure gas refrigerant discharged from the compressor 21a is branched, and the refrigerant heater 44a, the precooling heat exchanger 35a, the refrigerant cooler 36a, and the refrigerant cooling side flow rate control valve 37a. Through this, a flow that joins the receiver outlet pipe 28ba is obtained, and the refrigerant extracted from the receiver gas vent pipe 41a is heated by a part of the high-pressure gas refrigerant discharged from the compressor 21a. .

  In the bridge circuit 29a, when the refrigerant flows from the heat source side heat exchangers 24a, 25a toward the liquid side closing valve 31a side, and when the refrigerant flows from the liquid side closing valve 31a side to the heat source side heat exchangers 24a, 25a side. In any case of flowing in the direction, the refrigerant has a function of causing the refrigerant to flow into the receiver 28a through the receiver inlet pipe 28aa and out of the receiver 28a through the receiver outlet pipe 28ba. The bridge circuit 29a has four check valves 29aa, 29ba, 29ca, and 29da. The inlet check valve 29aa is a check valve that allows only the refrigerant to flow from the heat source side heat exchangers 24a and 25a to the receiver inlet pipe 28aa. The inlet check valve 29ba is a check valve that allows only the refrigerant to flow from the liquid side closing valve 31a side to the receiver inlet pipe 28aa. That is, the inlet check valves 29aa and 29ba have a function of circulating the refrigerant from the heat source side heat exchangers 24a and 25a side or the liquid side closing valve 31a side to the receiver inlet pipe 28aa. The outlet check valve 29ca is a check valve that allows only the refrigerant to flow from the receiver outlet pipe 28ba to the liquid side closing valve 31a. The outlet check valve 29da is a check valve that allows only the refrigerant to flow from the receiver outlet pipe 28ba to the heat source side heat exchangers 24a and 25a. That is, the outlet check valves 29ca and 29da have a function of circulating the refrigerant from the receiver outlet pipe 28ba to the heat source side heat exchangers 24a and 25a side or the liquid side closing valve 31a side.

  The high / low pressure switching mechanism 30a sends the high-pressure gas refrigerant discharged from the compressor 21a to the use-side refrigerant circuits 13a, 13b, 13c, and 13d (hereinafter referred to as “heat dissipation load operation state”). The discharge side of 21a and the high / low pressure gas side shut-off valve 32a are connected (see the broken line of the high / low pressure switching mechanism 30a in FIGS. 1 and 2), and the high pressure gas refrigerant discharged from the compressor 21a is used on the use side refrigerant circuit. When not sent to 13a, 13b, 13c, 13d (hereinafter referred to as “evaporation load operation state”), the high / low pressure gas side shut-off valve 32a and the suction side of the compressor 21a are connected (FIG. 1 and FIG. 1). 2 (see the solid line of the high / low pressure switching mechanism 30a in FIG. 2), which is a device capable of switching the flow path of the refrigerant in the heat source side refrigerant circuit 12a, and includes, for example, a four-way switching valve.

  The liquid side shutoff valve 31a, the high / low pressure gas side shutoff valve 32a, and the low pressure gas side shutoff valve 33a are provided at the connection ports with external devices and pipes (specifically, the refrigerant communication pipes 7, 8 and 9). It is a valve. The liquid side closing valve 31a is connected to the receiver inlet pipe 28aa or the receiver outlet pipe 28ba via the bridge circuit 29a. The high / low pressure gas side shut-off valve 32a is connected to the high / low pressure switching mechanism 30a. The low-pressure gas side closing valve 33a is connected to the suction side of the compressor 21a.

  The heat source unit 2a is provided with various sensors. Specifically, the suction pressure sensor 71a for detecting the pressure of the refrigerant on the suction side of the compressor 21a, the discharge pressure sensor 73a for detecting the pressure of the refrigerant on the discharge side of the compressor 21a, the receiver 28a and the heat source side heat exchange. The first liquid pipe temperature sensor 74 for detecting the temperature of the refrigerant flowing between the containers 24a and 25a, the degassing side temperature sensor 75a for detecting the temperature of the refrigerant flowing through the receiver degassing pipe 41a, the receiver 28a and the liquid side A second liquid pipe temperature sensor 80 for detecting the temperature of the refrigerant between the shut-off valve 31a is provided. Here, the degassing side temperature sensor 75 is provided in the receiver degassing pipe 41 so as to detect the temperature of the refrigerant at the outlet of the refrigerant heater 44. The heat source unit 2a includes a heat source side control unit 20a that controls operations of the respective units 21aa, 22a, 23a, 26a, 27a, 28ca, 30a, 34aa, 37a, and 42a that constitute the heat source unit 2a. And the heat source side control part 20a has the microcomputer and memory provided in order to control the heat source unit 2a, and uses side control part 50a, 50b, 50c of use unit 3a, 3b, 3c, 3d. , 50d can exchange control signals and the like.

<Connection unit>
The connection units 4a, 4b, 4c, and 4d are installed together with the use units 3a, 3b, 3c, and 3d in a room such as a building. The connection units 4a, 4b, 4c, and 4d are interposed between the utilization units 3, 4, and 5 and the heat source units 2a and 2b together with the refrigerant communication tubes 9, 10, and 11, and a part of the refrigerant circuit 10 is provided. It is composed.

  Next, the configuration of the connection units 4a, 4b, 4c, and 4d will be described. Since the connection unit 4a and the connection units 4b, 4c, and 4d have the same configuration, only the configuration of the connection unit 4a will be described here, and the configuration of the connection units 4b, 4c, and 4d will be described respectively. In place of the subscript “a” indicating the respective parts of 4a, the subscript “b”, “c” or “d” is attached, and the description of each part is omitted.

  The connection unit 4a mainly constitutes a part of the refrigerant circuit 10, and includes a connection side refrigerant circuit 14a (in the connection units 4b, 4c, and 4d, connection side refrigerant circuits 14b, 14c, and 14d, respectively). Yes. The connection side refrigerant circuit 14a mainly includes a liquid connection pipe 61a and a gas connection pipe 62a.

  The liquid connection pipe 61a connects the liquid refrigerant communication pipe 7 and the use side flow rate adjustment valve 51a of the use side refrigerant circuit 13a.

  The gas connection pipe 62a includes a high pressure gas connection pipe 63a connected to the high and low pressure gas refrigerant communication pipe 8, a low pressure gas connection pipe 64a connected to the low pressure gas refrigerant communication pipe 9, and a high pressure gas connection pipe 63a and a low pressure gas connection. It has a merged gas connection pipe 65a that merges the pipe 64a. The merged gas connection pipe 65a is connected to the gas side of the use side heat exchanger 52a of the use side refrigerant circuit 13a. The high pressure gas connection pipe 63a is provided with a high pressure gas on / off valve 66a capable of opening / closing control, and the low pressure gas connection pipe 64a is provided with a low pressure gas on / off valve 67a capable of opening / closing control.

  When the use unit 3a performs the cooling operation, the connection unit 4a opens the low-pressure gas on / off valve 67a and allows the refrigerant flowing into the liquid connection pipe 61a through the liquid refrigerant communication pipe 7 to be used on the use-side refrigerant circuit. The refrigerant evaporated by heat exchange with the indoor air in the use side heat exchanger 52a through the use side flow rate adjustment valve 51a of 13a and through the combined gas connection pipe 65a and the low pressure gas connection pipe 64a is sent through the use side heat exchanger 52a. It can function to return to the low-pressure gas refrigerant communication tube 9. Further, the connection unit 4a closes the low pressure gas on / off valve 67a and opens the high pressure gas on / off valve 66a when the use unit 3a performs the heating operation, and passes through the high / low pressure gas refrigerant communication pipe 8. The refrigerant flowing into the high-pressure gas connection pipe 63a and the merged gas connection pipe 65a is sent to the use-side heat exchanger 52a of the use-side refrigerant circuit 13a, and the refrigerant radiated by heat exchange with room air in the use-side heat exchanger 52a is It can function to return to the liquid refrigerant communication pipe 7 through the use side flow rate adjustment valve 51a and the liquid connection pipe 61a. Since this function has not only the connection unit 4a but also the connection units 4b, 4c, and 4d, the use side heat exchangers 52a, 52b, 52c, and 52d are connected by the connection units 4a, 4b, 4c, and 4d. Can be switched individually to function as a refrigerant evaporator or radiator.

  Moreover, the connection unit 4a has the connection side control part 60a which controls operation | movement of each part 66a, 67a which comprises the connection unit 4a. The connection-side control unit 60a includes a microcomputer and a memory provided for controlling the connection unit 60a, and exchanges control signals and the like with the use-side control unit 50a of the use unit 3a. Can be done.

  As described above, the use side refrigerant circuits 13a, 13b, 13c, 13d, the heat source side refrigerant circuits 12a, 12b, the refrigerant communication pipes 7, 8, 9 and the connection side refrigerant circuits 14a, 14b, 14c, 14d are provided. The refrigerant circuit 10 of the cooling / heating simultaneous operation type air conditioner 1 is configured by being connected. In the cooling and heating simultaneous operation type air conditioner 1, a plurality of (here, two) heat source units 2a including the compressors 21a and 21b, the heat source side heat exchangers 24a, 25a, 24b, and 25b and the receivers 28a and 28b. 2b and utilization units 3a, 3b, 3c, 3d having utilization side heat exchangers 52a, 52b, 52c, 52d are connected. And here, receiver liquid level detection pipes 43a and 43b for detecting whether or not the liquid level in the receivers 28a and 28b has reached the predetermined position L1 are provided on the receivers 28a and 28b of the heat source units 2a and 2b. The receiver liquid level detection pipes 43a and 43b are provided with gas vent side flow rate adjusting valves 42a and 42b that can be opened and closed.

(2) Operation | movement of freezing apparatus (cooling / heating simultaneous operation type air conditioning apparatus) Next, operation | movement of the cooling / heating simultaneous operation type air conditioning apparatus 1 is demonstrated.

  The operation mode of the cooling and heating simultaneous operation type air conditioner 1 roughly includes a normal operation mode that is a refrigeration cycle operation corresponding to a heat load required from the use side heat exchangers 52a, 52b, 52c, and 52d, It can be divided into a trial operation mode including a refrigeration cycle operation that is performed first after installation or maintenance.

  The normal operation mode includes a cooling operation, a heating operation, a cooling / heating simultaneous operation (evaporation load main body), and a cooling / heating simultaneous operation (heat radiation load main body). Here, in the cooling operation, there is only a use unit that performs a cooling operation (that is, an operation in which the use-side heat exchanger functions as an evaporator of the refrigerant), and the heat source-side heat exchanger with respect to the evaporation load of the entire use unit In this operation, 24a, 25a, 24b, and 25b function as a radiator for the refrigerant. In the heating operation, there are only use units that perform the heating operation (that is, the operation in which the use side heat exchanger functions as a refrigerant radiator), and the heat source side heat exchangers 24a and 25a with respect to the heat radiation load of the entire use unit. , 24b, 25b function as a refrigerant evaporator. Simultaneous cooling and heating operation (evaporation load mainly) is a cooling unit (that is, an operation in which the use side heat exchanger functions as a refrigerant evaporator) and a heating unit (ie, the use side heat exchanger is a refrigerant radiator). Use unit that performs the operation) and the heat load of the entire use unit is mainly the evaporation load, the first heat source side heat exchangers 24a and 24b are connected to the evaporation load of the entire use unit. This is an operation to function as a refrigerant radiator. Simultaneous cooling and heating operation (mainly heat radiation load) is a cooling unit (that is, an operation in which the use side heat exchanger functions as a refrigerant evaporator) and a heating unit (that is, the use side heat exchanger is a refrigerant radiator). Use units that perform the operation) and the heat load of the entire use unit is mainly the heat radiation load, the heat source side heat exchangers 24a, 25a, 24b, In this operation, 25b functions as a refrigerant evaporator.

  The trial operation mode includes an overfill detection operation. Here, the overfill detection operation is a refrigeration cycle operation for determining whether or not the refrigerant is overfilled in the refrigerant circuit 10, and whether or not the refrigerant is overfilled in the refrigerant circuit 10 during the overfill detection operation. Determine if.

  In addition, operation | movement of the heating / cooling simultaneous operation type air conditioning apparatus 1 containing these operation modes is performed by said control part 20a, 20b, 50a, 50b, 50c, 50d, 60a, 60b, 60c, 60d.

<Normal operation mode>
-Cooling operation-
During the cooling operation in the normal operation mode, for example, all of the usage units 3a, 3b, 3c, and 3d are in the cooling operation (that is, all of the usage-side heat exchangers 52a, 52b, 52c, and 52d function as a refrigerant evaporator. When the heat source side heat exchangers 24 and 25 function as refrigerant radiators, the refrigerant circuit 10 of the air conditioner 1 is configured as shown in FIG. 4 (for refrigerant flow, (See arrow attached to refrigerant circuit 10 in FIG. 4).

  Specifically, in the heat source units 2a and 2b, the first heat exchange switching mechanisms 22a and 22b are in a heat radiation operation state (the state shown by the solid lines of the first heat exchange switching mechanisms 22a and 22b in FIGS. 2 and 4). And switching the second heat exchange switching mechanism 23a, 23b to the heat radiation operation state (the state shown by the solid line of the second heat exchange switching mechanism 23a, 23b in FIGS. 2 and 4), thereby the heat source side heat exchanger 24a, 25a, 24b, and 25b are made to function as a refrigerant radiator. Further, the high / low pressure switching mechanisms 30a, 30b are switched to the evaporative load operation state (the state indicated by the solid lines of the high / low pressure switching mechanisms 30a, 30b in FIGS. 2 and 4). Moreover, the opening degree of the heat source side flow rate adjustment valves 26a, 27a, 26b, and 27b is adjusted, and the receiver inlet opening / closing valves 28ca and 28cb are in an open state. The refrigerant cooling side flow rate adjusting valves 37a and 37b are adjusted in opening so that high-pressure gas refrigerant discharged from the compressors 21a and 21b flows into the precooling heat exchangers 35a and 35b. In addition, the degassing side flow rate adjusting valves 42a and 42b as the degassing valves are adjusted in opening degree as necessary, but are basically fully closed (for this reason, in FIG. Flow not shown). In the connection units 4a, 4b, 4c and 4d, the use units 3a and 3b are opened by opening the high pressure gas on / off valves 66a, 66b, 66c and 66d and the low pressure gas on / off valves 67a, 67b, 67c and 67d. 3c, 3d use side heat exchangers 52a, 52b, 52c, 52d all function as refrigerant evaporators, and use units 3a, 3b, 3c, 3d use side heat exchangers 52a, 52b, 52c, All of 52d and the suction side of the compressor 21 of the heat source unit 2 are connected via the high and low pressure gas refrigerant communication pipe 8 and the low pressure gas refrigerant communication pipe 9. In the usage units 3a, 3b, 3c and 3d, the usage-side flow rate adjustment valves 51a, 51b, 51c and 51d are adjusted in opening.

  In such a refrigerant circuit 10, the high-pressure gas refrigerant compressed and discharged by the compressors 21a and 21b passes through the heat exchange switching mechanisms 22a, 23a, 22b and 23b, and heat source side heat exchange as a main heat source side heat exchanger. Sent to devices 24a, 25a, 24b, 25b. The high-pressure gas refrigerant compressed and discharged by the compressors 21a and 21b is also sent to the precooling heat exchangers 35a and 35b via the refrigerant heaters 44a and 44b. The high-pressure gas refrigerant sent to the heat source side heat exchangers 24a, 25a, 24b, and 25b is used as a heat source supplied by the outdoor fans 34a and 34b in the heat source side heat exchangers 24a, 25a, 24b, and 25b. Heat is dissipated by exchanging heat with outdoor air. The refrigerant that has radiated heat in the heat source side heat exchangers 24a, 25a, 24b, and 25b is adjusted in flow rate in the heat source side flow rate adjustment valves 26a, 27a, 26b, and 27b, and then merges to enter the inlet check valves 29aa and 29ab. And the receiver inlet opening / closing valves 28ca and 28cb. The high-pressure gas refrigerant sent to the precooling heat exchangers 35a and 35b also dissipates heat by exchanging heat with outdoor air as a heat source supplied by the outdoor fans 34a and 34b in the precooling heat exchangers 35a and 35b. To do. And the refrigerant | coolant thermally radiated in the pre-cooling heat exchangers 35a and 35b is sent to the refrigerant | coolant coolers 36a and 36b, and cools electrical equipment 20aa and 20ab. The refrigerant that has passed through the refrigerant coolers 36a and 36b is adjusted in flow rate by the refrigerant cooling side flow rate adjustment valves 37a and 37b, and then sent to the receiver outlet pipes 28ba and 28bb. Then, the refrigerant sent to the receivers 28a and 28b is temporarily stored in the receivers 28a and 28b, and then sent to the receiver outlet pipes 28ba and 28bb, where the outlet check valves 29ca and 29cb and the liquid side closing valve 31a are sent. , 31b to be sent to the liquid refrigerant communication tube 7 and merge.

  And the refrigerant | coolant which was sent to the liquid refrigerant communication pipe | tube 7 and merged is branched into four, and is sent to the liquid connection pipe | tube 61a, 61b, 61c, 61d of each connection unit 4a, 4b, 4c, 4d. The refrigerant sent to the liquid connection pipes 61a, 61b, 61c, 61d is sent to the usage-side flow rate adjustment valves 51a, 51b, 51c, 51d of the usage units 3a, 3b, 3c, 3d.

  The refrigerant sent to the usage-side flow rate adjustment valves 51a, 51b, 51c, 51d is adjusted in flow rate at the usage-side flow rate adjustment valves 51a, 51b, 51c, 51d, and then used-side heat exchangers 52a, 52b, 52c. , 52d evaporates into a low-pressure gas refrigerant by exchanging heat with the indoor air supplied by the indoor fans 53a, 53b, 53c, 53d. On the other hand, the room air is cooled and supplied to the room, and the use units 3a, 3b, 3c, and 3d are cooled. Then, the low-pressure gas refrigerant is sent to the merged gas connection pipes 65a, 65b, 65c, and 65d of the connection units 4a, 4b, 4c, and 4d.

  The low-pressure gas refrigerant sent to the merged gas connection pipes 65a, 65b, 65c, 65d passes through the high-pressure gas on / off valves 66a, 66b, 66c, 66d and the high-pressure gas connection pipes 63a, 63b, 63c, 63d. The gas refrigerant communication pipe 8 is sent and merged, and the low pressure gas on / off valves 67a, 67b, 67c and 67d and the low pressure gas connection pipes 64a, 64b, 64c and 64d are sent to the low pressure gas refrigerant communication pipe 9 and merged. .

  Then, the low-pressure gas refrigerant sent to the gas refrigerant communication pipes 8 and 9 is branched into two, and through the gas-side stop valves 32a, 32b, 33a, 33b and the high-low pressure switching mechanisms 30a, 30b, the compressor 21a. , 21b is returned to the suction side.

  In this way, the operation in the cooling operation is performed. In addition, some of the usage units 3a, 3b, 3c, and 3d perform a cooling operation (that is, an operation in which some of the usage-side heat exchangers 52a, 52b, 52c, and 52d function as a refrigerant evaporator). When the evaporation load of the entire use side heat exchangers 52a, 52b, 52c, 52d becomes small, only one of the heat source side heat exchangers 24, 25 (for example, the first heat source side heat exchangers 24a, 24b) is used as a refrigerant. The operation is performed to function as a heat radiator.

-Heating operation-
During the heating operation in the normal operation mode, for example, all of the usage units 3a, 3b, 3c, and 3d function as a heating operation (that is, all of the usage-side heat exchangers 52a, 52b, 52c, and 52d function as a refrigerant radiator). When the heat source side heat exchangers 24a, 25a, 24b, and 25b function as a refrigerant evaporator, the refrigerant circuit 10 of the air conditioner 1 is configured as shown in FIG. (For the flow, see the arrow attached to the refrigerant circuit 10 in FIG. 5).

  Specifically, in the heat source units 2a and 2b, the first heat exchange switching mechanisms 22a and 22b are in an evaporation operation state (a state indicated by the broken lines of the first heat exchange switching mechanisms 22a and 22b in FIGS. 2 and 5). And switching the second heat exchange switching mechanism 23a, 23b to the evaporating operation state (the state indicated by the broken lines of the second heat exchange switching mechanism 23a, 23b in FIGS. 2 and 5). 24a, 25a, 24b, and 25b are made to function as a refrigerant evaporator. Further, the high / low pressure switching mechanisms 30a, 30b are switched to the heat radiation load operating state (the state indicated by the broken lines of the high / low pressure switching mechanisms 30a, 30b in FIGS. 2 and 5). Moreover, the opening degree of the heat source side flow rate adjustment valves 26a, 27a, 26b, and 27b is adjusted, and the receiver inlet opening / closing valves 28ca and 28cb are in an open state. The refrigerant cooling side flow rate adjusting valves 37a and 37b are adjusted in opening so that high-pressure gas refrigerant discharged from the compressors 21a and 21b flows into the precooling heat exchangers 35a and 35b. In addition, the degassing side flow rate adjusting valves 42a and 42b as degassing valves are adjusted in opening degree as necessary, but are basically in a fully closed state (for this reason, also in FIG. Flow not shown). In the connection units 4a, 4b, 4c, and 4d, the high pressure gas on / off valves 66a, 66b, 66c, and 66d are opened, and the low pressure gas on / off valves 67a, 67b, 67c, and 67d are closed, thereby using the use unit 3a. 3b, 3c, 3d use side heat exchangers 52a, 52b, 52c, 52d all function as refrigerant radiators, and use units 3a, 3b, 3c, 3d use side heat exchangers 52a, 52b, All of 52c and 52d and the discharge side of the compressor 21 of the heat source unit 2 are connected via the high and low pressure gas refrigerant communication pipe 8. In the usage units 3a, 3b, 3c and 3d, the usage-side flow rate adjustment valves 51a, 51b, 51c and 51d are adjusted in opening.

  In such a refrigerant circuit 10, the high pressure gas refrigerant compressed and discharged by the compressors 21a and 21b passes through the high and low pressure switching mechanisms 30a and 30b and the high and low pressure gas side shut-off valves 32a and 32b. It is sent to 8 and merges. The high-pressure gas refrigerant compressed and discharged by the compressors 21a and 21b is also sent to the precooling heat exchangers 35a and 35b via the refrigerant heaters 44a and 44b. The high-pressure gas refrigerant sent to the precooling heat exchangers 35a and 35b radiates heat by exchanging heat with outdoor air as a heat source supplied by the outdoor fans 34a and 34b in the precooling heat exchangers 35a and 35b. To do. And the refrigerant | coolant thermally radiated in the pre-cooling heat exchangers 35a and 35b is sent to the refrigerant | coolant coolers 36a and 36b, and cools electrical equipment 20aa and 20ab. The refrigerant that has passed through the refrigerant coolers 36a and 36b is adjusted in flow rate by the refrigerant cooling side flow rate adjustment valves 37a and 37b, and then sent to the receiver outlet pipes 28ba and 28bb.

  The high-pressure gas refrigerant sent to the high / low-pressure gas refrigerant communication pipe 8 is branched into four high-pressure gas connection pipes 63a, 63b, 63c, 63d of the connection units 4a, 4b, 4c, 4d. Sent to. The high-pressure gas refrigerant sent to the high-pressure gas connection pipes 63a, 63b, 63c, 63d passes through the high-pressure gas on / off valves 66a, 66b, 66c, 66d and the merged gas connection pipes 65a, 65b, 65c, 65d. It is sent to the use side heat exchangers 52a, 52b, 52c, 52d of 3b, 3c, 3d.

  The high-pressure gas refrigerant sent to the use side heat exchangers 52a, 52b, 52c, and 52d is supplied by the indoor fans 53a, 53b, 53c, and 53d in the use side heat exchangers 52a, 52b, 52c, and 52d. Heat is dissipated by exchanging heat with indoor air. On the other hand, indoor air is heated and supplied indoors, and heating operation of utilization unit 3a, 3b, 3c, 3d is performed. The refrigerant radiated in the use side heat exchangers 52a, 52b, 52c, 52d is adjusted in flow rate in the use side flow rate adjusting valves 51a, 51b, 51c, 51d, and then the liquid connection pipes of the connection units 4a, 4b, 4c, 4d. 61a, 61b, 61c and 61d.

  Then, the refrigerant sent to the liquid connection pipes 61a, 61b, 61c, 61d is sent to the liquid refrigerant communication pipe 7 and merges.

  Then, the refrigerant that has been sent to the liquid refrigerant communication pipe 7 and merged is branched into two, and through the liquid side closing valves 31a and 31b, the inlet check valves 29ba and 29bb, and the receiver inlet on / off valves 28ca and 28cb, the receiver 28a. , 28b. The refrigerant sent to the receivers 28a and 28b is temporarily stored in the receivers 28a and 28b, then sent to the receiver outlet pipes 28ba and 28bb, and the heat source side flow rate adjustment through the outlet check valves 29da and 29db. Sent to both valves 26a, 27a, 26b, 27b. The refrigerant sent to the heat source side flow rate adjustment valves 26a, 27a, 26b, 27b is adjusted in flow rate at the heat source side flow rate adjustment valves 26a, 27a, 26b, 27b, and then the heat source side heat exchangers 24a, 25a, 24b. , 25b evaporates by exchanging heat with the outdoor air supplied by the outdoor fans 34a, 34b to become a low-pressure gas refrigerant, and is sent to the heat exchange switching mechanisms 22a, 23a, 22b, 23b. The low-pressure gas refrigerant sent to the heat exchange switching mechanisms 22a, 23a, 22b, and 23b merges and is returned to the suction side of the compressors 21a and 21b.

  In this way, the operation in the heating operation is performed. In addition, some of the usage units 3a, 3b, 3c, and 3d perform a heating operation (that is, an operation in which some of the usage-side heat exchangers 52a, 52b, 52c, and 52d function as a refrigerant radiator). When the heat radiation load of the entire use side heat exchangers 52a, 52b, 52c, 52d is small, only one of the heat source side heat exchangers 24, 25 (for example, the first heat source side heat exchangers 24a, 24b) is used as a refrigerant. The operation is performed so as to function as an evaporator.

-Simultaneous cooling and heating operation (mainly evaporation load)-
During simultaneous cooling / heating operation (mainly evaporation load) in the normal operation mode, for example, the utilization units 3a, 3b, 3c are in cooling operation, and the utilization unit 3d is in heating operation (that is, utilization side heat exchangers 52a, 52b, 52c functions as a refrigerant evaporator, and the use side heat exchanger 52d functions as a refrigerant radiator), and the first heat source side heat exchangers 24a and 24b function as a refrigerant radiator. The refrigerant circuit 10 of the air conditioning apparatus 1 is configured as shown in FIG. 6 (refer to the arrows attached to the refrigerant circuit 10 in FIG. 6 for the refrigerant flow).

  Specifically, in the heat source units 2a and 2b, the first heat exchange switching mechanisms 22a and 22b are in a heat radiation operation state (the state shown by the solid lines of the first heat exchange switching mechanisms 22a and 22b in FIGS. 2 and 6). By switching to, the first heat source side heat exchangers 24a and 24b are made to function as refrigerant radiators. Further, the high / low pressure switching mechanisms 30a, 30b are switched to the heat radiation load operating state (the state shown by the broken lines of the high / low pressure switching mechanisms 30a, 30b in FIGS. 2 and 6). The opening amounts of the first heat source side flow rate adjustment valves 26a and 26b are adjusted, the second heat source side flow rate adjustment valves 27a and 27b are closed, and the receiver inlet on / off valves 28ca and 28cb are opened. It has become. The refrigerant cooling side flow rate adjusting valves 37a and 37b are adjusted in opening so that high-pressure gas refrigerant discharged from the compressors 21a and 21b flows into the precooling heat exchangers 35a and 35b. In addition, the degassing side flow rate adjusting valves 42a and 42b as the degassing valves are adjusted in opening degree as necessary, but are basically fully closed (for this reason, in FIG. Flow not shown). In the connection units 4a, 4b, 4c, and 4d, the high-pressure gas on-off valve 66d and the low-pressure gas on-off valves 67a, 67b, and 67c are opened, and the high-pressure gas on-off valves 66a, 66b, 66c, and the low-pressure gas By closing the on-off valve 67d, the use side heat exchangers 52a, 52b, 52c of the use units 3a, 3b, 3c function as a refrigerant evaporator, and the use side heat exchanger 52d of the use unit 3d. Through the low-pressure gas refrigerant communication pipe 9 between the utilization side heat exchangers 52a, 52b, 52c of the utilization units 3a, 3b, 3c and the suction side of the compressor 21 of the heat source unit 2. The use side heat exchanger 52d of the use unit 3d and the discharge side of the compressor 21 of the heat source unit 2 are connected to the high / low pressure gas refrigerant communication pipe 8 in a connected state. To have become the connected state. In the usage units 3a, 3b, 3c and 3d, the usage-side flow rate adjustment valves 51a, 51b, 51c and 51d are adjusted in opening.

  In such a refrigerant circuit 10, a part of the high-pressure gas refrigerant compressed and discharged by the compressors 21a and 21b passes through the high-low pressure switching mechanisms 30a, 30b and the high-low pressure gas side shut-off valves 32a, 32b. It is sent to the low-pressure gas refrigerant communication pipe 8 and merges, and the remainder is sent to the first heat source side heat exchangers 24a and 24b through the first heat exchange switching mechanisms 22a and 22b. The high-pressure gas refrigerant compressed and discharged by the compressors 21a and 21b is also sent to the precooling heat exchangers 35a and 35b via the refrigerant heaters 44a and 44b.

  Then, the high-pressure gas refrigerant sent to the high-low pressure gas refrigerant communication pipe 8 and joined together is sent to the high-pressure gas connection pipe 63d of the connection unit 4d. The high-pressure gas refrigerant sent to the high-pressure gas connection pipe 63d is sent to the use-side heat exchanger 52d of the use unit 3d through the high-pressure gas on-off valve 66d and the merged gas connection pipe 65d.

  The high-pressure gas refrigerant sent to the use side heat exchanger 52d dissipates heat by exchanging heat with the indoor air supplied by the indoor fan 53d in the use side heat exchanger 52d. On the other hand, the indoor air is heated and supplied indoors, and the heating operation of the utilization unit 3d is performed. The refrigerant that has radiated heat in the use side heat exchanger 52d is sent to the liquid connection pipe 61d of the connection unit 4d after the flow rate is adjusted in the use side flow rate adjustment valve 51d.

  Further, the high-pressure gas refrigerant sent to the first heat source side heat exchangers 24a and 24b is used as outdoor air and heat as a heat source supplied by the outdoor fans 34a and 34b in the first heat source side heat exchangers 24a and 24b. Heat is dissipated by replacement. The refrigerant radiated in the first heat source side heat exchangers 24a and 24b is adjusted in flow rate in the first heat source side flow rate adjusting valves 26a and 26b, and then the inlet check valves 29aa and 29ab and the receiver inlet on / off valves 28ca and 28cb. To the receivers 28a and 28b. The high-pressure gas refrigerant sent to the precooling heat exchangers 35a and 35b also dissipates heat by exchanging heat with outdoor air as a heat source supplied by the outdoor fans 34a and 34b in the precooling heat exchangers 35a and 35b. To do. And the refrigerant | coolant thermally radiated in the pre-cooling heat exchangers 35a and 35b is sent to the refrigerant | coolant coolers 36a and 36b, and cools electrical equipment 20aa and 20ab. The refrigerant that has passed through the refrigerant coolers 36a and 36b is adjusted in flow rate by the refrigerant cooling side flow rate adjustment valves 37a and 37b, and then sent to the receiver outlet pipes 28ba and 28bb. Then, the refrigerant sent to the receivers 28a and 28b is temporarily stored in the receivers 28a and 28b, and then sent to the receiver outlet pipes 28ba and 28bb, where the outlet check valves 29ca and 29cb and the liquid side closing valve 31a are sent. , 31b to be sent to the liquid refrigerant communication tube 7 and merge.

  Then, the refrigerant that radiates heat in the use side heat exchanger 52d and is sent to the liquid connection pipe 61d is sent to the liquid refrigerant communication pipe 7, and radiates heat in the first heat source side heat exchangers 24a and 24b to communicate with the liquid refrigerant. It further merges with the refrigerant sent to the pipe 7 and merged.

  And the refrigerant | coolant merged in the liquid refrigerant communication pipe | tube 7 branches into three, and is sent to the liquid connection pipes 61a, 61b, 61c of each connection unit 4a, 4b, 4c. Then, the refrigerant sent to the liquid connection pipes 61a, 61b, 61c is sent to the use side flow rate adjusting valves 51a, 51b, 51c of the use units 3a, 3b, 3c.

  The refrigerant sent to the usage-side flow rate adjustment valves 51a, 51b, 51c is adjusted in flow rate at the usage-side flow rate adjustment valves 51a, 51b, 51c, and then the indoor fan in the usage-side heat exchangers 52a, 52b, 52c. By exchanging heat with the indoor air supplied by 53a, 53b, 53c, it evaporates and becomes a low-pressure gas refrigerant. On the other hand, the room air is cooled and supplied to the room, and the use units 3a, 3b, and 3c are cooled. Then, the low-pressure gas refrigerant is sent to the merged gas connection pipes 65a, 65b, and 65c of the connection units 4a, 4b, and 4c.

  The low-pressure gas refrigerant sent to the merged gas connection pipes 65a, 65b, 65c is sent to the low-pressure gas refrigerant communication pipe 9 through the low-pressure gas on-off valves 67a, 67b, 67c and the low-pressure gas connection pipes 64a, 64b, 64c. Be merged.

  The low-pressure gas refrigerant sent to the low-pressure gas refrigerant communication pipe 9 is branched into two and returned to the suction side of the compressors 21a and 21b through the gas-side shutoff valves 33a and 33b.

  Thus, the operation in the simultaneous cooling and heating operation (evaporation load main body) is performed. Note that the evaporation load of the entire use side heat exchangers 52a, 52b, 52c, and 52d is reduced due to a decrease in the number of use units (that is, use side heat exchangers functioning as refrigerant evaporators) that perform the cooling operation. In this case, the second heat source side heat exchanger 25 functions as a refrigerant evaporator, so that the heat radiation load of the first heat source side heat exchangers 24a and 24b and the second heat source side heat exchangers 25a and 25b are reduced. An operation for canceling the evaporation load and reducing the heat radiation load of the heat source side heat exchangers 24a, 25a, 24b, and 25b as a whole is performed.

<Cooling and heating simultaneous operation mode (heat radiation load mainly)>
During the simultaneous cooling / heating operation (mainly evaporation load) in the normal operation mode, for example, the use units 3a, 3b, 3c perform heating operation, and the use unit 3d performs cooling operation (that is, use side heat exchangers 52a, 52b, 52c functions as a refrigerant radiator, and the use side heat exchanger 52d functions as a refrigerant evaporator), and the heat source side heat exchangers 24a, 25a, 24b, and 25b function as a refrigerant evaporator. In doing so, the refrigerant circuit 10 of the air-conditioning apparatus 1 is configured as shown in FIG. 7 (refer to the arrows attached to the refrigerant circuit 10 in FIG. 7 for the flow of the refrigerant).

  Specifically, in the heat source units 2a and 2b, the first heat exchange switching mechanisms 22a and 22b are in an evaporating operation state (the state indicated by the broken lines of the first heat exchange switching mechanisms 22a and 22b in FIGS. 2 and 7). And switching the second heat exchange switching mechanisms 23a, 23b to the evaporation operation state (the state indicated by the broken lines of the second heat exchange switching mechanisms 23a, 23b in FIG. 2 and FIG. 7). 24a, 25a, 24b, and 25b are made to function as a refrigerant evaporator. Further, the high / low pressure switching mechanisms 30a, 30b are switched to the heat radiation load operating state (the state shown by the broken lines of the high / low pressure switching mechanisms 30a, 30b in FIGS. 2 and 7). Moreover, the opening degree of the heat source side flow rate adjustment valves 26a, 27a, 26b, and 27b is adjusted, and the receiver inlet opening / closing valves 28ca and 28cb are in an open state. The refrigerant cooling side flow rate adjusting valves 37a and 37b are adjusted in opening so that high-pressure gas refrigerant discharged from the compressors 21a and 21b flows into the precooling heat exchangers 35a and 35b. In addition, the degassing side flow rate adjusting valves 42a and 42b as degassing valves are adjusted in opening degree as necessary, but are basically in a fully closed state (for this reason, also in FIG. Flow not shown). In the connection units 4a, 4b, 4c and 4d, the high pressure gas on / off valves 66a, 66b and 66c and the low pressure gas on / off valve 67d are opened, and the high pressure gas on / off valve 66d and the low pressure gas on / off valve 67a, By closing 67b and 67c, the utilization side heat exchangers 52a, 52b and 52c of the utilization units 3a, 3b and 3c function as refrigerant radiators, and the utilization side heat exchanger 52d of the utilization unit 3d. As a refrigerant evaporator, the utilization side heat exchanger 52d of the utilization unit 3d and the suction side of the compressor 21 of the heat source unit 2 are connected via the low-pressure gas refrigerant communication pipe 9, and The use side heat exchangers 52a, 52b, 52c of the use units 3a, 3b, 3c and the discharge side of the compressor 21 of the heat source unit 2 connect the high / low pressure gas refrigerant communication pipe 8. To have become the connected state. In the usage units 3a, 3b, 3c and 3d, the usage-side flow rate adjustment valves 51a, 51b, 51c and 51d are adjusted in opening.

  In such a refrigerant circuit 10, the high pressure gas refrigerant compressed and discharged by the compressors 21a and 21b passes through the high and low pressure switching mechanisms 30a and 30b and the high and low pressure gas side shut-off valves 32a and 32b. It is sent to 8 and merges. The high-pressure gas refrigerant compressed and discharged by the compressors 21a and 21b is also sent to the refrigerant heaters 44a and 44b. The high-pressure gas refrigerant sent to the precooling heat exchangers 35a and 35b radiates heat by exchanging heat with outdoor air as a heat source supplied by the outdoor fans 34a and 34b in the precooling heat exchangers 35a and 35b. To do. And the refrigerant | coolant thermally radiated in the pre-cooling heat exchangers 35a and 35b is sent to the refrigerant | coolant coolers 36a and 36b, and cools electrical equipment 20aa and 20ab. The refrigerant that has passed through the refrigerant coolers 36a and 36b is adjusted in flow rate by the refrigerant cooling side flow rate adjustment valves 37a and 37b, and then sent to the receiver outlet pipes 28ba and 28bb.

  The high-pressure gas refrigerant sent to the high-low pressure gas refrigerant communication pipe 8 and merged is branched into three and sent to the high-pressure gas connection pipes 63a, 63b, 63c of the connection units 4a, 4b, 4c. The high-pressure gas refrigerant sent to the high-pressure gas connection pipes 63a, 63b, and 63c passes through the high-pressure gas on / off valves 66a, 66b, and 66c and the merged gas connection pipes 65a, 65b, and 65c, and the use side of the use units 3a, 3b, and 3c. It is sent to the heat exchangers 52a, 52b, 52c.

  The high-pressure gas refrigerant sent to the use side heat exchangers 52a, 52b, 52c exchanges heat with the indoor air supplied by the indoor fans 53a, 53b, 53c in the use side heat exchangers 52a, 52b, 52c. To dissipate heat. On the other hand, room air is heated and supplied indoors, and heating operation of utilization unit 3a, 3b, 3c is performed. The refrigerant that has dissipated heat in the usage-side heat exchangers 52a, 52b, and 52c is adjusted in flow rate in the usage-side flow rate adjustment valves 51a, 51b, and 51c, and then into the liquid connection pipes 61a, 61b, and 61c of the connection units 4a, 4b, and 4c. Sent.

  Then, the refrigerant sent to the liquid connection pipes 61a, 61b, 61c, 61d is sent to the liquid refrigerant communication pipe 7 and merges.

  A part of the refrigerant merged in the liquid refrigerant communication pipe 7 is sent to the liquid connection pipe 61d of the connection unit 4d, and the rest is branched into two, the liquid side shut-off valves 31a and 31b, the inlet check valve It is sent to the receivers 28a and 28b through 29ba and 29bb and the receiver inlet on-off valves 28ca and 28cb.

  The refrigerant sent to the liquid connection pipe 61d of the connection unit 4d is sent to the usage-side flow rate adjustment valve 51d of the usage unit 3d.

  The refrigerant sent to the use-side flow rate adjustment valve 51d is subjected to heat exchange with the indoor air supplied by the indoor fan 53d in the use-side heat exchanger 52d after the flow rate is adjusted in the use-side flow rate adjustment valve 51d. As a result, it evaporates into a low-pressure gas refrigerant. On the other hand, the indoor air is cooled and supplied to the room, and the cooling operation of the utilization unit 3d is performed. Then, the low-pressure gas refrigerant is sent to the merged gas connection pipe 65d of the connection unit 4d.

  The low-pressure gas refrigerant sent to the merged gas connection pipe 65d is sent to the low-pressure gas refrigerant communication pipe 9 through the low-pressure gas on-off valve 67d and the low-pressure gas connection pipe 64d.

  The low-pressure gas refrigerant sent to the low-pressure gas refrigerant communication pipe 9 is branched into two and returned to the suction side of the compressors 21a and 21b through the gas-side shutoff valves 33a and 33b.

  The refrigerant sent to the receivers 28a and 28b is temporarily stored in the receivers 28a and 28b, then sent to the receiver outlet pipes 28ba and 28bb, and the heat source side flow rate adjustment through the outlet check valves 29da and 29db. Sent to both valves 26a, 27a, 26b, 27b. The refrigerant sent to the heat source side flow rate adjustment valves 26a, 27a, 26b, 27b is adjusted in flow rate at the heat source side flow rate adjustment valves 26a, 27a, 26b, 27b, and then the heat source side heat exchangers 24a, 25a, 24b. , 25b evaporates by exchanging heat with the outdoor air supplied by the outdoor fans 34a, 34b to become a low-pressure gas refrigerant, and is sent to the heat exchange switching mechanisms 22a, 23a, 22b, 23b. The low-pressure gas refrigerant sent to the heat exchange switching mechanisms 22a, 23a, 22b, and 23b merges and is returned to the suction side of the compressors 21a and 21b.

  In this way, the operation in the simultaneous cooling and heating operation (mainly heat radiation load) is performed. Note that the heat radiation load of the entire use side heat exchangers 52a, 52b, 52c, and 52d is reduced due to a decrease in the number of use units (that is, use side heat exchangers functioning as refrigerant radiators) that perform the heating operation. In this case, the first heat source side heat exchangers 24a and 24b function as a refrigerant radiator, so that the heat radiation load of the first heat source side heat exchangers 24a and 24b and the second heat source side heat exchangers 25a and 25b. The operation of canceling the evaporation load is reduced and the evaporation load of the heat source side heat exchangers 24a, 25a, 24b, and 25b is reduced.

<Trial run mode>
Next, the operation in the overfill detection operation in the trial operation mode will be described with reference to FIGS. Here, FIG. 8 is a flowchart of the overfill detection operation in the trial operation mode. FIG. 9 is a diagram illustrating an operation (refrigerant flow) in the overfill detection operation in the trial operation mode.

  Here, at the site, the heat source units 2a and 2b preliminarily filled with the refrigerant, the utilization units 3a, 3b, 3c, and 3d, and the connection units 4a, 4b, 4c, and 4d are connected to the refrigerant communication tubes 7, 8, 9 An example of a test run after the refrigerant circuit 10 is connected to the refrigerant circuit 10 after the refrigerant communication pipe 7, 8, 9 is additionally filled in the refrigerant circuit 10 will be described.

  First, the shutoff valves 31a, 31b, 32a, 32b, 33a, 33b of the heat source units 2a, 2b are opened, and the refrigerant circuit 10 is filled with the refrigerant preliminarily charged in the heat source units 2a, 2b.

  Next, when a serviceman or the like issues a command to perform an overfill detection operation in the trial operation mode through a remote controller (not shown) or the control units 20a, 20b, 50a, 50b, 50c, 50d, etc., the following steps are performed. Overfilling detection operation is performed in the procedure from ST1 to step ST4.

  When an overfill detection operation start command is issued, the overfill detection operation in step ST1 is started. This overfill detection operation is a refrigeration cycle operation for determining whether or not the refrigerant is overfilled in the refrigerant circuit 10, and here, as in the cooling operation in the normal operation mode (see FIG. 4), the use unit All of 3a, 3b, 3c, and 3d perform a cooling operation (that is, all of the use side heat exchangers 52a, 52b, 52c, and 52d function as a refrigerant evaporator), and a plurality of heat source units 2a, 2b In which all the heat source side heat exchangers 24a, 25a, 24b, and 25b function as refrigerant radiators (hereinafter referred to as “all-use unit cooling operation”). When this all-use unit cooling operation is performed, the state of the refrigerant circulating in the refrigerant circuit 10 is stabilized, and a large amount of liquid refrigerant is stored in the heat source side heat exchangers 24a, 25a, 24b, 25b, A state is created in which liquid refrigerant does not accumulate as much as possible in the receivers 28a and 28b of the heat source units 2a and 2b.

  Further, in this overfill detection operation, all-use unit cooling operation may be performed, and device control for further stabilizing the state of the refrigerant circulating in the refrigerant circuit 10 as described below may be performed. Specifically, the rotational speeds of the outdoor fans 34a and 34b are controlled so that the high pressure in the refrigerant circuit 10 (here, the pressure of the refrigerant detected by the discharge pressure sensors 73a and 73b is used) becomes the target high pressure (hereinafter referred to as the “high pressure”). , “High pressure control”). Further, the operation capacity of the compressors 21a and 21b is controlled so that the low pressure in the refrigerant circuit 10 (here, the pressure of the refrigerant detected by the suction pressure sensors 71a and 71b is used) becomes the target low pressure (hereinafter referred to as “low pressure”). Control "). Further, the use side flow rate adjusting mechanisms 51a, 51b, 51c, 51d are arranged so that the superheat degree of the refrigerant at the outlets of the use side heat exchangers 52a, 52b, 52c, 52d functioning as the refrigerant evaporator becomes the target superheat degree. The opening degree may be controlled (hereinafter referred to as “superheat degree control”). Here, when the high pressure control is performed, the high pressure in the refrigerant circuit 10 is stabilized, so that the high pressure portion in the refrigerant circuit 10 (for example, the heat source side heat exchangers 24a, 25a, 24b, 25b, the liquid refrigerant communication pipe 7, etc.). The amount of refrigerant is further stabilized. Further, when the low pressure control and the superheat degree control are performed, the low pressure in the refrigerant circuit 10 and the dryness of the refrigerant are stabilized, so that the low pressure portion (for example, the use side heat exchangers 52a, 52b, 52c, 52d, The amount of refrigerant in the gas refrigerant communication pipes 8 and 9) is further stabilized. That is, by performing the high pressure control, the low pressure control, and the superheat control, the degree of stability of the state of the refrigerant circulating in the refrigerant circuit 10 can be further improved.

  As described above, when the overfill detection operation accompanied by the all-use unit cooling operation is started in Step ST1, a large amount of liquid refrigerant is accumulated in the heat source side heat exchangers 24a, 25a, 24b, and 25b as described above. The condition is the degree of refrigerant supercooling SCa, SCb (here, the refrigerant pressure detected by the discharge pressure sensors 73a, 73b) at the outlets of the heat source side heat exchangers 24a, 25a, 24b, 25b that function as a refrigerant radiator. Is converted into a refrigerant saturation temperature, and this saturation temperature is used as a value obtained by subtracting the refrigerant temperature from the refrigerant temperature detected by the first liquid pipe temperature sensor 74. Here, the degree of supercooling SCa is the degree of supercooling at the outlets of the heat source side heat exchangers 24a and 25a of the heat source unit 2a, and the degree of supercooling SCb is the outlet of the heat source side heat exchangers 24b and 25b of the heat source unit 2b. Is the degree of supercooling. That is, the heat source side heat exchangers 24a, 25a, 24b, 25b of the respective heat source units 2a, 2b according to the amount of the liquid refrigerant accumulated in the heat source side heat exchangers 24a, 25a, 24b, 25b of the respective heat source units 2a, 2b. Change occurs in the degree of supercooling SCa and SCb of the refrigerant at the outlet of the refrigerant.

  Whether the refrigerant is overfilled in the refrigerant circuit 10 using the receiver liquid level detection tubes 43a and 43b provided in the heat source units 2a and 2b without performing the determination processes in steps ST2 and ST3 described later. It is also possible to determine whether or not. That is, the receiver liquid level detection pipes 43a and 43b are connected to the liquid level position L1 at which it can be determined that the refrigerant is overfilled, and this liquid level position L1 is used as the predetermined liquid level of the receivers 28a and 28b. Similarly to step ST4 described later, the degassing side flow rate adjusting valves 42a and 42b as degassing valves are opened to detect whether or not the receivers 28a and 28b have reached the predetermined liquid level L1, and the receivers 28a and 28b When the surface L1 is reached, it is determined that the refrigerant is overfilled.

  However, since this air conditioner 1 employs a configuration in which a plurality of (here, two) heat source units 2a and 2b are connected, there is a risk that the refrigerant will drift between the heat source units 2a and 2b. When the refrigerant is biased in the heat source unit, the heat source unit having a receiver reaching the predetermined liquid level L1 even though the refrigerant circuit 10 is filled with a specified amount of refrigerant and the refrigerant is not overfilled. May be determined to exist, and there is a risk of erroneous detection that the refrigerant is overfilled.

  Therefore, here, prior to the overfill detection in step ST4, in step ST2, in order to detect the presence or absence of refrigerant drift between the plurality of (here, two) heat source units 2a and 2b during the overfill detection operation. Is detected between the plurality of heat source units 2a and 2b, and it is determined whether the relationship between the drift detection state quantities satisfies the non-drift condition. Here, as the drift detection state quantity, the supercooling degrees SCa and SCb of the refrigerant at the outlets of the heat source side heat exchangers 24a, 25a, 24b and 25b of the heat source units 2a and 2b are employed. This is because, as described above, the degree of supercooling SCa, SCb of the refrigerant at the outlets of the heat source side heat exchangers 24a, 25a, 24b, 25b of the heat source units 2a, 2b is the heat source side heat exchanger of the heat source units 2a, 2b. 24a, 25a, 24b, 25b is a state quantity that changes according to the amount of liquid refrigerant that accumulates in the heat source side heat exchangers 24a, 25a, 24b, 25b of each heat source unit 2a, 2b. This is because the amount greatly affects the amount of liquid refrigerant accumulated in the receivers 28a and 28b of the heat source units 2a and 2b.

  Specifically, the degree of supercooling SCa on the heat source unit 2a side is compared with the degree of supercooling SCb on the heat source unit 2b side. For example, if the temperature difference is within a predetermined supercooling degree difference ΔSC, the heat source unit 2a 2b, no drift occurs, and it is determined that the non-drift condition is satisfied. When three or more heat source units are connected, for example, when the temperature difference is within a predetermined temperature difference ΔSC by comparing the largest and smallest supercooling degree SC, the heat source unit It is determined that there is no drift between them and the non-drift condition is satisfied. The drift detection state quantity is not limited to the refrigerant subcooling degrees SCa and SCb at the outlets of the heat source side heat exchangers 24a, 25a, 24b and 25b of the heat source units 2a and 2b. Other state quantities may be used as long as they are equivalent to SCa and SCb.

  Here, in addition to the determination process in step ST2, in step ST3, a plurality of (here, two) heat source units 2a, 2b and use units 3a, 3b, 3c, 3d are connected in the refrigerant circuit 10. The portion between the receivers 28a, 28b including the liquid refrigerant communication pipe 7 to be used and the use side heat exchangers 52a, 52b, 52c, 52d is determined whether or not a liquid filling condition satisfying the liquid refrigerant is satisfied. . Specifically, the refrigerant temperature detected by the second liquid pipe temperature sensors 80a and 80b is compared with the saturation temperature of the refrigerant obtained by converting the refrigerant pressure detected by the discharge pressure sensors 73a and 73b. For example, when the temperature of the refrigerant detected by the second liquid pipe temperature sensors 80a and 80b is lower, it is determined that the liquid filling condition is satisfied. Here, whether or not the liquid filling condition is satisfied is determined in the liquid pipe portion where a large amount of liquid refrigerant is accumulated in the same manner as the heat source side heat exchangers 24a, 25a, 24b, and 25b during the overfill detection operation. This is to create a state in which liquid refrigerant is not collected as much as possible in the receivers 28a and 28b of the heat source units 2a and 2b.

  And after performing the determination process of step ST2, ST3 and satisfy | filling both non-diffusion conditions and liquid full conditions, it transfers to the process of step ST4.

  In step ST4, in each of the heat source units 2a and 2b, the degassing side flow rate adjustment valves 42a and 42b are opened as degassing valves to detect whether or not the liquid level in the receivers 28a and 28b has reached the predetermined position L1. Thus, it is determined whether or not the refrigerant circuit 10 is overfilled with refrigerant. Specifically, if any one of the receivers 28a and 28b of each heat source unit 2a and 2b has reached the predetermined liquid level L1, it is determined that overfilling has occurred, and each heat source unit 2a If neither of the receivers 28a and 28b of 2b reach the predetermined liquid level L1, it is determined that overfilling has not occurred and the refrigerant circuit 10 is filled with a specified amount of refrigerant. To do. As described above, in the configuration in which the plurality of heat source units 2a and 2b are connected as described above, when the overfill detection is performed by the receiver liquid level detection tubes 43a and 43b, the receiver liquid level detection tubes 43a and 43b The timing for performing the overfilling detection by opening the gas vent side flow rate control valves 42a and 42b as the gas vent valves is after satisfying a non-biased condition in which it is considered that no refrigerant drift has occurred between the heat source units 2a and 2b. ing.

  In addition, the liquid level detection in the receiver 28 by the receiver liquid level detection tubes 43a and 43b is performed as follows. First, as shown in FIGS. 3 and 9, the receiver liquid level detection pipes 43a and 43b are cooled from a predetermined height position L1 of the receivers 28a and 28b when the degassing side flow rate adjustment valves 42a and 42b are opened. Extract. Here, the refrigerant extracted from the receiver liquid level detection tubes 43a and 43b is in a gas state when the liquid level in the receivers 28a and 28b is lower than the predetermined height position L1, and the refrigerant in the receivers 28a and 28b. When the liquid level is equal to or higher than the predetermined height position L1, the liquid state is entered.

  Next, the refrigerant extracted from the receiver liquid level detection tubes 43a and 43b merges with the refrigerant extracted from the receiver degassing tubes 41a and 41b, as shown in FIGS. Here, the refrigerant extracted from the receiver degassing pipes 41a and 41b is in a gas state when the liquid level in the receivers 28a and 28b is lower than the height position L2 (see FIG. 3). For this reason, when the refrigerant extracted from the receiver liquid level detection tubes 43a and 43b is in a gas state, the receiver degassing tubes 41a and 41b are merged with the refrigerant extracted from the receiver degassing tubes 41a and 41b. The refrigerant flowing through is also in a gas state. On the other hand, when the refrigerant extracted from the receiver liquid level detection tubes 43a and 43b is in a liquid state, the receiver gas extraction tubes 41a and 41b are connected to the refrigerant extracted from the receiver gas extraction tubes 41a and 41b. The flowing refrigerant is in a gas-liquid two-phase state in which the liquid refrigerant is mixed with the gas refrigerant. And the refrigerant | coolant which flows through the receiver degassing pipe | tube 41a, 41b after the refrigerant | coolant extracted from the receiver liquid level detection pipe | tube 43a, 43b merged is suck | inhaled by compressor 21a, 21b by degassing side flow control valve 42a, 42b. The pressure is reduced to near the refrigerant pressure on the side. Due to the depressurization operation by the degassing flow rate control valves 42a and 42b, the refrigerant flowing through the receiver degassing pipes 41a and 41b undergoes a temperature drop according to the state of the refrigerant before the depressurization operation. That is, when the refrigerant flowing through the receiver degassing pipes 41a and 41b is in a gas state, the temperature drop due to the decompression operation is small, and when it is in the gas-liquid two-phase state, the temperature drop due to the decompression operation is large. For this reason, although not adopted here, the receiver liquid level detection pipe 43a is used by using the temperature of the refrigerant flowing through the receiver gas vent pipes 41a and 41b after being depressurized by the gas vent side flow control valves 42a and 42b. It is also possible to detect whether the refrigerant extracted from 43b is in a liquid state (whether the liquid level in the receivers 28a, 28b has reached the height position L1).

  Next, the refrigerant flowing through the receiver degassing pipes 41a and 41b after being depressurized by the degassing side flow rate adjusting valves 42a and 42b is sent to the refrigerant heaters 44a and 44b as shown in FIGS. Thus, heat is exchanged with the high-pressure gas refrigerant flowing between the discharge sides of the compressors 21a and 21b and the precooling heat exchangers 35a and 35b. As a result of the heating operation by the refrigerant heaters 44a and 44b, the refrigerant flowing through the receiver degassing pipes 41a and 41b is increased in temperature according to the state of the refrigerant before the heating operation. That is, when the refrigerant flowing through the receiver degassing pipes 41a and 41b after being depressurized by the degassing flow rate control valves 42a and 42b is in a gas state, the temperature rise due to the heating operation is large, and the gas-liquid two-phase state In this case, the temperature rise due to the pressure reducing operation is reduced. For this reason, the temperature of the refrigerant flowing through the receiver degassing pipes 41a and 41b after being heated by the refrigerant heaters 44a and 44b is detected by the degassing side temperature sensors 75a and 75b, and this is detected. Whether or not the refrigerant extracted from the receiver liquid level detection tubes 43a and 43b is in a liquid state using the temperature of the refrigerant (whether the liquid level in the receivers 28a and 43b has reached the height position L1). Detected. Specifically, by subtracting the refrigerant saturation temperature obtained by converting the refrigerant pressure detected by the suction pressure sensors 71a and 71b from the refrigerant temperature detected by the degassing temperature sensors 75a and 75b, The degree of superheat of the refrigerant flowing through the receiver degassing pipes 41a and 41b after being heated by the refrigerant heaters 44a and 44b is obtained. When the degree of superheat of the refrigerant is equal to or greater than a predetermined temperature difference, the refrigerant extracted from the receiver liquid level detection tubes 43a and 43b is in a gas state (the liquid levels in the receivers 28a and 43b are high). If the superheat degree of the refrigerant does not reach a predetermined temperature difference, the refrigerant extracted from the receiver liquid level detection tubes 43a and 43b is in a liquid state (receiver 28a). , 28b has reached the height position L1).

  In this way, the operation in the overfill detection operation in the trial operation mode is performed.

(3) Features of the refrigeration apparatus (cooling / heating simultaneous operation type air conditioner) The cooling / heating simultaneous operation type air conditioner 1 has the following characteristics.

<A>
Here, as described above, in the configuration in which a plurality of (here, two) heat source units 2a and 2b are connected, when the overfilling detection is performed by the receiver liquid level detection tubes 43a and 43b, the receiver liquid level detection tube 43a. , 43b satisfy the non-flow condition that opens the degassing flow rate control valves 42a and 42b as the degassing valve and performs the overfill detection timing when it is considered that no refrigerant flow has occurred between the heat source units 2a and 2b. After.

  Thereby, here, overfill detection by the receiver liquid level detection tubes 43a and 43b can be performed without erroneous detection in a state in which no refrigerant drift occurs between the heat source units 2a and 2b.

<B>
Here, as described above, as the overfill detection operation, the operation of causing the heat source side heat exchangers 24a, 25a, 24b, and 25b of the heat source units 2a and 2b to function as a refrigerant radiator is used. During the detection operation, a large amount of liquid refrigerant is stored in the heat source side heat exchangers 24a, 25a, 24b, and 25b so as to create a state in which liquid refrigerant does not collect as much as possible in the receivers 28a and 28b of the heat source units 2a and 2b. I have to.

  In addition, here, as described above, during the overfill detection operation, the liquid pipe portion (the receiver 28a including the liquid refrigerant communication pipe 7) in which a large amount of liquid refrigerant is accumulated similarly to the heat source side heat exchangers 24a, 25a, 24b, and 25b. , 28b and the use-side heat exchangers 52a, 52b, 52c, 52d), the liquid refrigerant is surely accumulated in the receivers 28a, 28b of the heat source units 2a, 2b as much as possible. I try to create a state that does not accumulate.

  Thereby, here, when overfilling has not occurred, and when there is no refrigerant drift between a plurality of (here, two) heat source units 2a and 2b, each heat source unit 2a When the liquid level of the receivers 2a and 28b of 2b is kept in a stable operation state at a liquid level position lower than the predetermined liquid level L1, and a refrigerant drift occurs between the plurality of heat source units 2a and 2b or overfilling When this occurs, the change in the liquid level of the receivers 28a and 28b can be clearly shown.

<C>
Here, as described above, the heat source side heat exchangers 24a, 25a, and the heat source side heat exchangers 24a, 25a, 2a, 2b, which change depending on the amount of liquid refrigerant accumulated in the heat source side heat exchangers 24a, 25a, 24b, 25b, A state quantity equivalent to the degree of supercooling SCa, SCb of the refrigerant at the outlets 24b, 25b or the degree of supercooling SCa, SCb is used as a drift detection state quantity.

  Thereby, here, during the overfill detection operation, the heat source side heat exchanger 24a of each heat source unit 2a, 2b that greatly affects the amount of liquid refrigerant accumulated in the receivers 28a, 28b of each heat source unit 2a, 2b, By comparing the amount of liquid refrigerant that accumulates in 25a, 24b, and 25b, it is possible to accurately determine whether or not the non-drift condition is satisfied.

(4) Modifications In the above embodiment, the configuration example of the cooling and heating simultaneous operation type air conditioner 1 is described as a refrigeration apparatus to which the present invention is applied. However, the present invention is not limited to this. For example, the present invention can be applied to other refrigeration apparatuses such as a cooling / heating switching operation type air conditioner as long as a plurality of heat source units having receivers and a utilization unit are connected. .

  In the above embodiment, the receiver liquid level detection pipes 43a and 43b are also used as the receiver gas vent pipes 41a and 41b, and the gas vent side flow rate adjustment valves 42a and 42b are opened when the liquid level is detected. Although it functions also as a drain valve, it is not limited to this. For example, the receiver liquid level detection pipes 43a and 43b are provided independently from the receiver gas vent pipes 41a and 41b, and the receiver liquid level detection pipes 43a and 43b are provided with gas vent valves. Good. In this case, the gas vent valve may be a valve capable of opening / closing control such as an electromagnetic valve instead of the electric expansion valve. The receiver liquid level detection tubes 43a and 43b are provided with refrigerant heaters 44a and 44b. However, the heating source is not limited to the high-pressure gas refrigerant discharged from the compressors 21a and 21b. It may be a liquid refrigerant flowing through the outlet pipes 28ba and 28bb.

  In the above embodiment, each of the heat source units 2a and 2b is provided with a plurality of heat source side heat exchangers. However, the present invention is not limited to this, and there may be only one.

  The present invention provides a refrigeration apparatus including a refrigerant circuit configured by connecting a plurality of heat source units having a compressor, a heat source side heat exchanger, and a receiver, and a utilization unit having a utilization side heat exchanger. On the other hand, it is widely applicable.

1 Cooling and heating simultaneous operation type air conditioner (refrigeration equipment)
2a, 2b Heat source unit 3a, 3b, 3c, 3d Utilization unit 7 Liquid refrigerant communication tube 10 Refrigerant circuit 21a, 21b Compressor 24a, 25a, 24b, 25b Heat source side heat exchanger 28a, 28b Receiver 42a, 42b Degassing side flow rate Control valve (gas vent valve)
43a, 43b Receiver liquid level detection tube 52a, 52b, 52c, 52d Use side heat exchanger

JP 2006-292212 A

Claims (4)

A plurality of heat source units (2a, 2b) having a compressor (21a, 21b), a heat source side heat exchanger (24a, 25a, 24b, 25b) and a receiver (28a, 28b), and a use side heat exchanger (52a) , 52b, 52c, 52d) in a refrigeration apparatus including a refrigerant circuit (10) configured by being connected to utilization units (3a, 3b, 3c, 3d),
Each receiver is connected to a receiver liquid level detection tube (43a, 43b) for detecting whether the liquid level in the receiver has reached a predetermined position,
Each receiver liquid level detection tube is provided with a degassing valve (42a, 42b) that can be opened and closed,
Performing an overfill detection operation that is a refrigeration cycle operation for determining whether or not the refrigerant is overfilled in the refrigerant circuit;
During the overfill detection operation, the drift detection state quantity, which is a state quantity for detecting the presence or absence of refrigerant drift between the plurality of heat source units, is compared between the plurality of heat source units. Whether or not the refrigerant circuit is overfilled by detecting whether or not the liquid level in the receiver has reached a predetermined position by opening the degassing valve Determine
Refrigeration equipment (1). In the overfill detection operation, the use side heat exchangers (52a, 52b, 52c, 52d) function as a refrigerant evaporator, and the heat source side heat exchangers (24a, 25a, 24b, 25b) are operated. It is an operation that functions as a refrigerant radiator.
The refrigeration apparatus (1) according to claim 1. The drift detection state quantity is a state quantity equivalent to the degree of supercooling of the refrigerant at the outlet of each heat source side heat exchanger (24a, 25a, 24b, 25b) functioning as a refrigerant radiator or the degree of supercooling. Is,
The refrigeration apparatus (1) according to claim 2. A liquid refrigerant communication pipe (7) that satisfies the non-biased condition and connects the plurality of heat source units (2a, 2b) and the utilization units (3a, 3b, 3c, 3d) in the refrigerant circuit (10). The gas vent valve (42a) when a liquid filling condition in which a portion between the receiver (28a, 28b) and the use side heat exchanger (52a, 52b, 52c, 52d) is filled with liquid refrigerant is satisfied. 42b),
The refrigeration apparatus (1) according to claim 2 or 3.

Images