JPWO2006003925A1 - Refrigeration apparatus and air conditioner - Google Patents

Abstract

In a refrigeration apparatus and an air conditioner having a refrigerant circuit having an evaporator configured to allow refrigerant to flow in from the lower side and flow out from the upper side, the control range when the evaporation capacity of the evaporator is controlled by the expansion valve is increased. Expanding. The air conditioner (1) includes a refrigerant circuit (12) and a first oil return circuit (101). The refrigerant circuit (12) includes a compression mechanism (21), a heat source side heat exchanger (23) configured to allow refrigerant to flow in from below and flow out from above when functioning as an evaporator, A plurality of use side refrigerant circuits (12a, 12b, 12c) are connected to the heat source side refrigerant circuit (12d) configured to be connected to the side expansion valve (24), and are 30 ° C. or less. A combination of refrigerating machine oil and refrigerant that does not separate into two layers in the temperature range is used. The first oil return circuit (101) is connected to the lower part of the heat source side heat exchanger (23) and returns the refrigeration oil accumulated in the heat source side heat exchanger (23) to the compression mechanism (21) together with the refrigerant. [Selection] Figure 1

Description

  The present invention relates to a refrigeration apparatus and an air conditioner, and more particularly, to a refrigeration apparatus and an air conditioner including a refrigerant circuit having an evaporator configured so that a refrigerant flows in from the lower side and flows out from the upper side.

2. Description of the Related Art Conventionally, there is a refrigeration apparatus provided with a vapor compression refrigerant circuit having a heat exchanger configured such that a refrigerant flows in from the lower side and flows out from the upper side as a refrigerant evaporator (see, for example, Patent Document 1). .). In this refrigeration system, in order to prevent the refrigerating machine oil from accumulating in the evaporator, the refrigerating machine oil that has been separated into two layers and floated on the liquid surface of the refrigerant is separated because the specific gravity is smaller than that of the refrigerant. The refrigerant is extracted from near the liquid level and returned to the suction side of the compressor.
Further, as an example of a refrigeration apparatus including a vapor compression refrigerant circuit, steam having a heat source side refrigerant circuit having a plurality of heat source side heat exchangers and a plurality of usage side refrigerant circuits connected to the heat source side refrigerant circuit There is an air conditioner including a compression type refrigerant circuit (for example, see Patent Document 2). In such an air conditioner, a heat source side expansion valve is provided so that the flow rate of the refrigerant flowing into each heat source side heat exchanger can be adjusted. In this air conditioner, for example, when the heat source side heat exchanger functions as an evaporator during heating operation or simultaneous cooling and heating operation, the air conditioning load of the plurality of use side refrigerant circuits as a whole decreases. If the air-conditioning load of the entire plurality of usage-side refrigerant circuits is very small, control is performed to reduce the evaporation capacity by reducing the opening of the heat-source-side expansion valve. Evaporation capacity can be reduced by reducing the number of heat source side heat exchangers that function as evaporators by closing some parts, or as evaporators by making some of the heat source side heat exchangers function as condensers Control is performed to reduce the evaporation capacity by offsetting the evaporation capacity of the functioning heat source side heat exchanger.

In the above-described air conditioner, for example, when the heat source side heat exchanger functions as a condenser during cooling operation or simultaneous cooling and heating operation, the air conditioning load of the entire plurality of use side refrigerant circuits is reduced. Accordingly, by reducing the opening degree of the heat source side expansion valve connected to the heat source side heat exchanger, the amount of liquid refrigerant accumulated in the heat source side heat exchanger is increased to reduce the substantial heat transfer area. Control is performed to reduce the condensation capacity. However, when control is performed to reduce the opening of the heat source side expansion valve, the refrigerant pressure on the downstream side of the heat source side expansion valve (specifically, between the heat source side expansion valve and the use side refrigerant circuit) tends to decrease. As a result, there is a problem that the control for reducing the condensation capacity of the heat source side refrigerant circuit cannot be stably performed. On the other hand, a high-pressure gas refrigerant compressed by the compressor is provided on the downstream side of the heat source side expansion valve by providing a pressurization circuit that joins the refrigerant that is decompressed in the heat source side expansion valve and sent to the use side refrigerant circuit. The control which raises the refrigerant pressure of the side is proposed (for example, refer to patent documents 3).
JP 63-204074 A JP-A-3-260561 Japanese Patent Laid-Open No. 3-129259

  In the above air conditioner, when functioning as a refrigerant evaporator, a heat exchanger such as a plate heat exchanger configured such that the refrigerant flows in from the lower side and flows out from the upper side is used as the heat source side heat exchanger. There is a case. In this case, in order to prevent the refrigerating machine oil from accumulating in the heat source side heat exchanger, it is necessary to maintain the liquid level of the refrigerant in the heat source side heat exchanger so as to be at a certain level or higher. However, when the heat source side heat exchanger is made to function as an evaporator having a small evaporation capacity, such as when the air conditioning load in a plurality of use side refrigerant circuits becomes very small, the opening degree of the heat source side expansion valve is made small. Even if an attempt is made to reduce the amount of refrigerant flowing through the heat source side heat exchanger, the opening of the heat source side expansion valve cannot be made too small due to the restriction of the refrigerant level in the heat source side heat exchanger. Evaporation capacity cannot be controlled sufficiently only by adjusting the opening of the side expansion valve. As a result, the number of heat source side heat exchangers functioning as evaporators can be reduced by closing some of the heat source side expansion valves. Controls to reduce the evaporation capacity by offsetting the evaporation capacity of the heat source side heat exchanger functioning as an evaporator by reducing the evaporation capacity by making a part of the multiple heat source side heat exchangers function as a condenser. Do Door has become necessary.

For this reason, the number of parts and the cost increase due to the installation of a plurality of heat source side heat exchangers, and a part of the plurality of heat source side heat exchangers functions as a condenser to reduce the evaporation capacity That is, the amount of refrigerant compressed in the compressor increases by the amount of refrigerant condensed in the heat source side heat exchanger, and the COP in the operating condition where the air conditioning load of the plurality of use side refrigerant circuits as a whole is small is deteriorated. There's a problem.
Further, in the above-described air conditioner, by providing a pressure circuit in the refrigerant circuit, when the heat source side heat exchanger functions as a refrigerant condenser, the pressure is reduced in the heat source side expansion valve and sent to the use side refrigerant circuit. When the high-pressure gas refrigerant compressed by the compressor is combined with the refrigerant to be produced, the refrigerant sent from the heat source side expansion valve to the utilization side refrigerant circuit becomes a gas-liquid two-phase flow, and the heat source side expansion valve is opened. The smaller the degree, the larger the gas fraction of the refrigerant after the high-pressure gas refrigerant is merged from the pressurization circuit, resulting in uneven flow between the plurality of usage-side refrigerant circuits. There is a problem that the opening degree of the expansion valve cannot be made sufficiently small. As a result, as in the case where the heat source side heat exchanger functions as a refrigerant evaporator, the heat source side refrigerant circuit is provided with a plurality of heat source side heat exchangers, and the air conditioning load of the entire plurality of usage side refrigerant circuits is extremely high. If it is smaller, the condensation capacity can be reduced by closing the multiple heat source side expansion valves to reduce the number of heat source side heat exchangers functioning as condensers, or a part of the multiple heat source side heat exchangers can be used. By making it function as an evaporator, it is necessary to control to reduce the condensing capacity by offsetting the condensing capacity of the heat source side heat exchanger functioning as a condenser.

For this reason, the number of parts and the cost increase due to the installation of a plurality of heat source side heat exchangers, and a part of the plurality of heat source side heat exchangers functions as an evaporator to reduce the condensation capacity That is, the amount of refrigerant compressed in the compressor increases by the amount of refrigerant evaporated in the heat source side heat exchanger, and the COP in the operating condition where the air conditioning load of the entire plurality of usage side refrigerant circuits is small deteriorates. There's a problem.
An object of the present invention is to control an evaporation capacity of an evaporator by an expansion valve in a refrigeration apparatus and an air conditioner having a refrigerant circuit configured to have an evaporator configured to flow in from the lower side and out from the upper side. The purpose of this is to expand the control range.

The refrigeration apparatus according to the first invention includes a refrigerant circuit and an oil return circuit. The refrigerant circuit is configured by connecting a compression mechanism, a condenser, an expansion valve, and an evaporator configured so that the refrigerant flows in from the lower side and flows out from the upper side, and has a temperature of 30 ° C. or lower. A combination of refrigerating machine oil and refrigerant that does not separate into two layers in the range is used. The oil return circuit is connected to the lower part of the evaporator, and returns the refrigeration oil accumulated in the evaporator to the compression mechanism together with the refrigerant.
This refrigeration apparatus includes a refrigerant circuit having an evaporator configured so that the refrigerant flows in from the lower side and flows out from the upper side, and the refrigerating machine oil and the refrigerant used in the refrigerant circuit have a temperature of 30 ° C. or less. A combination of refrigerating machine oil and refrigerant that does not separate into two layers in the temperature range is used. Here, the evaporating temperature of the refrigerant in the evaporator is a temperature of 30 ° C. or lower when water, air, or brine is used as the heat source. For this reason, in this refrigeration apparatus, the refrigerating machine oil does not accumulate in the state of floating on the liquid level of the refrigerant in the evaporator, but accumulates in the evaporator in a state of being mixed with the refrigerant. The refrigerating machine oil collected in the evaporator is returned to the compression mechanism together with the refrigerant by an oil return circuit connected to the lower part of the evaporator. For this reason, unlike the conventional refrigeration apparatus, it is not necessary to maintain the liquid level of the refrigerant in the heat source side heat exchanger at a certain level or higher in order to prevent the refrigerating machine oil from collecting in the evaporator. .
As a result, in this refrigeration system, control is performed to reduce the evaporation capacity of the evaporator by reducing the opening of the expansion valve in accordance with the refrigeration load. As a result, the liquid level of the refrigerant in the evaporator decreases. However, since refrigeration oil does not accumulate in the evaporator, it is possible to expand the control range when the evaporation capacity of the evaporator is controlled by the expansion valve.

The refrigerating apparatus according to the second invention is the refrigerating apparatus according to the first invention, wherein the refrigerating machine oil and the refrigerant used in the refrigerant circuit are a combination of refrigerating machine oil that does not separate into two layers in a temperature range of −5 ° C. or lower, and Refrigerant.
In this refrigeration apparatus, a combination of refrigerating machine oil and refrigerant that does not separate into two layers in a temperature range of −5 ° C. or lower is used as a combination of refrigerating machine oil and refrigerant. For this reason, in this refrigeration apparatus, even when the evaporation temperature of the refrigerant in the evaporator is low, the refrigerating machine oil does not accumulate in a state floating on the liquid level of the refrigerant in the evaporator, but evaporates in a state mixed with the refrigerant. Even in such a case, the refrigerating machine oil can be prevented from collecting in the evaporator.

The refrigerating apparatus according to the third invention is the refrigerating apparatus according to the second invention, wherein the combination of the refrigerating machine oil and the refrigerant used in the refrigerant circuit is ether oil and R410A.
In this refrigeration apparatus, ether oil is used as the refrigerating machine oil, and R410A is used as the refrigerant. This combination of refrigerating machine oil and refrigerant does not separate into two layers in a temperature range of −5 ° C. or lower, but even in such a case, refrigerating machine oil can be prevented from accumulating in the evaporator.

The refrigeration apparatus according to a fourth aspect of the present invention is the refrigeration apparatus according to any one of the first to third aspects of the present invention, which joins with the refrigeration oil and the refrigerant returned from the lower part of the heat source side heat exchanger to the compression mechanism through the oil return circuit. It further includes a differential pressure increasing mechanism for increasing the differential pressure between.
In the refrigeration apparatus according to any one of the first to third inventions, the flow rates of the refrigerating machine oil and the refrigerant returned from the lower part of the evaporator to the compression mechanism through the oil return circuit are such that the lower part of the evaporator and the compression mechanism are For example, the pressure loss in the evaporator or in the pipe from the refrigerant outlet side of the evaporator to the suction side of the compression mechanism is small, and the pressure loss in the oil return circuit is In such a case, it becomes impossible to return the refrigerating machine oil and refrigerant having a flow rate sufficient to prevent the refrigerating machine oil from accumulating in the evaporator from the lower part of the evaporator to the compression mechanism through the oil return circuit. Cases can arise.
However, in this refrigeration apparatus, since the differential pressure increasing mechanism is provided, the flow rate of the refrigerating machine oil and refrigerant returned from the lower part of the evaporator to the compression mechanism through the oil return circuit can be increased. Refrigerating machine oil and refrigerant having a flow rate sufficient to prevent the refrigerating machine oil from accumulating in the chamber can be reliably returned to the compression mechanism from the lower part of the evaporator through the oil return circuit.

A refrigeration apparatus according to a fifth invention includes a refrigerant circuit and an oil return circuit. The refrigerant circuit is configured by connecting a compression mechanism, a condenser, an expansion valve, and an evaporator configured so that the refrigerant flows in from the lower side and flows out from the upper side. A combination of refrigerating machine oil and refrigerant that does not separate into layers is used. The oil return circuit is connected to the lower part of the evaporator, and returns the refrigeration oil accumulated in the evaporator to the compression mechanism together with the refrigerant.
This refrigeration apparatus includes a refrigerant circuit having an evaporator configured to allow refrigerant to flow in from the lower side and flow out from the upper side, and as refrigeration oil and refrigerant used in the refrigerant circuit, A combination of refrigerating machine oil and refrigerant that does not separate into two layers is used. For this reason, in this refrigeration system, the refrigerating machine oil does not accumulate in a state where it floats on the liquid level of the refrigerant in the evaporator under the condition of the evaporation temperature of the refrigerant in the evaporator, but in a state where it is mixed with the refrigerant. It will be accumulated in. The refrigerating machine oil collected in the evaporator is returned to the compression mechanism together with the refrigerant by an oil return circuit connected to the lower part of the evaporator. For this reason, unlike the conventional refrigeration apparatus, it is not necessary to maintain the liquid level of the refrigerant in the heat source side heat exchanger at a certain level or higher in order to prevent the refrigerating machine oil from collecting in the evaporator. .
As a result, in this refrigeration system, control is performed to reduce the evaporation capacity of the evaporator by reducing the opening of the expansion valve in accordance with the refrigeration load. As a result, the liquid level of the refrigerant in the evaporator decreases. However, since refrigeration oil does not accumulate in the evaporator, it is possible to expand the control range when the evaporation capacity of the evaporator is controlled by the expansion valve.

An air conditioner according to a sixth aspect of the invention includes a refrigerant circuit and an oil return circuit. The refrigerant circuit is configured by connecting a compression mechanism, a heat source side heat exchanger configured so that refrigerant flows in from the lower side and flows out from the upper side when functioning as an evaporator, and a heat source side expansion valve. The heat-source-side refrigerant circuit is configured by connecting a plurality of use-side refrigerant circuits configured by connecting a use-side heat exchanger and a use-side expansion valve. A combination of refrigerating machine oil and refrigerant that does not separate into layers is used. The oil return circuit is connected to the lower part of the heat source side heat exchanger, and returns the refrigeration oil accumulated in the heat source side heat exchanger to the compression mechanism together with the refrigerant.
In this air conditioner, when functioning as an evaporator, a heat source side refrigerant circuit having a heat source side heat exchanger configured so that refrigerant flows in from the lower side and flows out from the upper side, and a plurality of usage side refrigerant circuits And a refrigerant oil and refrigerant used in the refrigerant circuit are combined with a refrigerant oil and refrigerant that are not separated into two layers in a temperature range of 30 ° C. or lower. Yes. Here, the evaporating temperature of the refrigerant in the heat source side heat exchanger is a temperature of 30 ° C. or lower when water, air, or brine is used as the heat source. For this reason, in this air conditioner, the refrigerating machine oil is not stored in a state floating on the liquid level of the refrigerant in the heat source side heat exchanger, but is stored in the heat source side heat exchanger in a state mixed with the refrigerant. Become. The refrigerating machine oil accumulated in the heat source side heat exchanger is returned to the compression mechanism together with the refrigerant by an oil return circuit connected to the lower part of the heat source side heat exchanger. For this reason, in order to prevent the refrigeration oil from accumulating in the heat source side heat exchanger as in the conventional air conditioner, the liquid level of the refrigerant in the heat source side heat exchanger is maintained at a certain level or more. There is no need to do it.

Thereby, in this air conditioning apparatus, control is performed to reduce the evaporation capability of the heat source side heat exchanger by reducing the opening of the heat source side expansion valve in accordance with the air conditioning load of the plurality of usage side refrigerant circuits, and as a result Because the refrigerant oil does not accumulate in the heat source side heat exchanger even if the refrigerant level in the heat source side heat exchanger decreases, the evaporation capacity of the heat source side heat exchanger is controlled by the heat source side expansion valve This makes it possible to expand the control range when doing so.
And in this air conditioner, when providing a plurality of heat source side heat exchangers and causing the heat source side heat exchanger to function as an evaporator as in the conventional air conditioner, some of the plurality of heat source side expansion valves By reducing the number of heat source side heat exchangers that function as evaporators and by reducing the number of heat source side heat exchangers, or by functioning a part of multiple heat source side heat exchangers as condensers Since it is not necessary to perform control to reduce the evaporation capacity by offsetting the evaporation capacity of the heat source side heat exchanger, a wide range of control of the evaporation capacity can be obtained by a single heat source side heat exchanger.

  This makes it possible to unify the heat source side heat exchanger in an air conditioner where unification of the heat source side heat exchanger has not been realized due to the control width limitation of the evaporation capacity control of the heat source side heat exchanger. Therefore, the increase in the number of parts and cost increase caused by installing multiple heat source side heat exchangers in the conventional air conditioner can be prevented, and some of the multiple heat source side heat exchangers can be condensed. When the evaporation capacity is reduced by functioning as a heat exchanger, the amount of refrigerant compressed in the compression mechanism increases by the amount of refrigerant condensed in the heat source side heat exchanger, and the air conditioning load of the entire plurality of usage side refrigerant circuits is small It is possible to solve the problem that the COP in the operating condition is deteriorated.

The refrigeration apparatus according to a seventh aspect of the present invention is the air conditioner according to the sixth aspect of the invention, wherein the refrigeration oil and refrigerant used in the refrigerant circuit are a combination of refrigeration oils that do not separate into two layers in a temperature range of -5 ° C or lower And refrigerant.
In this refrigeration apparatus, a combination of refrigerating machine oil and refrigerant that does not separate into two layers in a temperature range of −5 ° C. or lower is used as a combination of refrigerating machine oil and refrigerant. For this reason, in this refrigeration apparatus, the refrigerating machine oil is stored in a state floating on the liquid level of the refrigerant in the heat source side heat exchanger even when the evaporation temperature of the refrigerant in the heat source side heat exchanger functioning as an evaporator is low. Instead, it is stored in the heat source side heat exchanger in a state of being mixed with the refrigerant. Even in such a case, it is possible to prevent the refrigerating machine oil from collecting in the heat source side heat exchanger.

An air conditioner according to an eighth aspect of the present invention is the air conditioner according to the seventh aspect of the present invention, wherein the combination of refrigerating machine oil and refrigerant used in the refrigerant circuit is ether oil and R410A.
In this air conditioner, ether oil is used as the refrigerating machine oil, and R410A is used as the refrigerant. In the combination of the refrigerating machine oil and the refrigerant, since the two layers are not separated in a temperature range of −5 ° C. or lower, the refrigerating machine oil can be prevented from collecting in the heat source side heat exchanger.

An air conditioner according to a ninth aspect is the air conditioner according to any of the sixth to eighth aspects, wherein the refrigerating machine oil and the refrigerant are returned to the compression mechanism from the lower part of the heat source side heat exchanger through the oil return circuit. It further includes a differential pressure increasing mechanism that increases the differential pressure during the merge.
In the air conditioner according to any of the sixth to eighth inventions, the flow rates of the refrigerating machine oil and the refrigerant returned to the compression mechanism from the lower part of the heat source side heat exchanger functioning as an evaporator through the oil return circuit are the oil return circuit. Is determined according to the pressure loss between the lower part of the heat source side heat exchanger functioning as an evaporator and the compression mechanism, for example, in the heat source side heat exchanger functioning as an evaporator or in the heat source side heat exchanger When the pressure loss in the pipe from the refrigerant outlet side to the suction side of the compression mechanism is small and the pressure loss in the oil return circuit becomes small, the refrigeration oil accumulates in the heat source side heat exchanger. There may be a case where the refrigerating machine oil and the refrigerant having a sufficient flow rate that can be prevented cannot be returned to the compression mechanism from the lower part of the heat source side heat exchanger through the oil return circuit.
However, in this air conditioner, by providing the differential pressure increasing mechanism, the flow rates of the refrigerating machine oil and the refrigerant returned from the lower part of the heat source side heat exchanger to the compression mechanism through the oil return circuit can be increased. Therefore, refrigeration oil and refrigerant at a sufficient flow rate that can prevent the refrigeration oil from accumulating in the heat source side heat exchanger are reliably transferred from the lower part of the heat source side heat exchanger to the compression mechanism through the oil return circuit. Can be returned.

An air conditioner according to a tenth aspect of the present invention is the air conditioner according to any of the sixth to ninth aspects of the invention, wherein the oil return circuit has an on-off valve. The on-off valve is closed when the heat source side heat exchanger functions as a condenser, and is opened when the heat source side heat exchanger functions as an evaporator.
In this air conditioner, an on / off valve is provided in the oil return circuit, and when the heat source side heat exchanger functions as a condenser, the heat source side heat exchanger is condensed by operating with the on / off valve closed. After that, it is possible to prevent the amount of refrigerant sent to the use side refrigerant circuit from decreasing.

An air conditioner according to an eleventh aspect of the invention is the air conditioner according to the tenth aspect of the invention, wherein the on-off valve is opened when the opening degree of the heat source side expansion valve becomes equal to or less than a predetermined opening degree.
In this air conditioner, it is not necessary to use the oil return circuit until the liquid level of the refrigerant in the heat source side heat exchanger exceeds a certain level at which the refrigerating machine oil does not accumulate, so there is no need to use the oil return circuit in the heat source side heat exchanger. Set the opening of the heat source side expansion valve corresponding to the coolant level where refrigerating machine oil can accumulate as a predetermined opening, and open and close only when the opening of the heat source side expansion valve falls below this predetermined opening By operating with the valve opened, it is possible to prevent an increase in the amount of refrigerant sent to the compression mechanism without being evaporated in the heat source side heat exchanger.

An air conditioner according to a twelfth aspect of the invention is the air conditioner according to any of the sixth to eleventh aspects of the invention, wherein the heat source side heat exchanger is independent of the flow rate of the refrigerant flowing through the heat source side heat exchanger. A fixed amount of water is used as a heat source.
In this air conditioner, a constant amount of water is used as a heat source regardless of the flow rate of the refrigerant flowing in the heat source side heat exchanger, and the evaporation capacity in the heat source side heat exchanger is controlled by controlling the amount of water. I can't. However, in this air conditioner, the control range when the evaporation capacity of the heat source side heat exchanger is controlled by the heat source side expansion valve is expanded, so even if the amount of water is not controlled, the heat source side heat exchanger It is possible to secure a control width when controlling the evaporation capacity of the.

An air conditioner according to a thirteenth aspect is the air conditioner according to any of the sixth to twelfth aspects, wherein the heat source side heat exchanger is a plate heat exchanger.
In this air conditioner, a plate-type heat exchanger is used as the heat source side heat exchanger, and due to its structure, in order to prevent refrigerating machine oil from collecting in the heat source side heat exchanger, it is above the liquid level of the refrigerant. It is difficult to extract the refrigerating machine oil accumulated in a floating state from the vicinity of the liquid level of the refrigerant. However, in this air conditioner, the refrigerating machine oil is accumulated in the heat source side heat exchanger in a state of being mixed with the refrigerant, and the refrigerating machine oil accumulated in the heat source side heat exchanger is extracted together with the refrigerant from the lower part of the heat source side heat exchanger. Therefore, even if a plate heat exchanger is used, the oil return circuit can be easily installed.

An air conditioner according to a fourteenth aspect of the present invention includes a refrigerant circuit and an oil return circuit. The refrigerant circuit is configured by connecting a compression mechanism, a heat source side heat exchanger configured so that refrigerant flows in from the lower side and flows out from the upper side when functioning as an evaporator, and a heat source side expansion valve. The heat source side refrigerant circuit is configured by connecting a plurality of usage side refrigerant circuits configured by connecting a usage side heat exchanger and a usage side expansion valve, and the heat source side heat exchanger is an evaporator. A combination of refrigerating machine oil and refrigerant that does not separate into two layers in the heat source side heat exchanger when functioning as a heat source is used. The oil return circuit is connected to the lower part of the heat source side heat exchanger, and returns the refrigeration oil accumulated in the heat source side heat exchanger to the compression mechanism together with the refrigerant.
In this air conditioner, when functioning as an evaporator, a heat source side refrigerant circuit having a heat source side heat exchanger configured so that refrigerant flows in from the lower side and flows out from the upper side, and a plurality of usage side refrigerant circuits Are connected to each other, and as the refrigerating machine oil and refrigerant used in the refrigerant circuit, two layers are formed in the heat source side heat exchanger when the heat source side heat exchanger functions as an evaporator. Refrigerating machine oil and refrigerant in a combination that does not separate into two are used. For this reason, in this air conditioner, the refrigerating machine oil is stored in a state floating on the liquid level of the refrigerant in the heat source side heat exchanger under the condition of the refrigerant evaporation temperature in the heat source side heat exchanger functioning as an evaporator. Instead, it is accumulated in the heat source side heat exchanger in a mixed state with the refrigerant. The refrigerating machine oil accumulated in the heat source side heat exchanger is returned to the compression mechanism together with the refrigerant by an oil return circuit connected to the lower part of the heat source side heat exchanger. For this reason, in order to prevent the refrigeration oil from accumulating in the heat source side heat exchanger as in the conventional air conditioner, the liquid level of the refrigerant in the heat source side heat exchanger is maintained at a certain level or more. There is no need to do it.

Thereby, in this air conditioning apparatus, control is performed to reduce the evaporation capability of the heat source side heat exchanger by reducing the opening of the heat source side expansion valve in accordance with the air conditioning load of the plurality of usage side refrigerant circuits, and as a result Because the refrigerant oil does not accumulate in the heat source side heat exchanger even if the refrigerant level in the heat source side heat exchanger decreases, the evaporation capacity of the heat source side heat exchanger is controlled by the heat source side expansion valve This makes it possible to expand the control range when doing so.
And in this air conditioner, when providing a plurality of heat source side heat exchangers and causing the heat source side heat exchanger to function as an evaporator as in the conventional air conditioner, some of the plurality of heat source side expansion valves By reducing the number of heat source side heat exchangers that function as evaporators and by reducing the number of heat source side heat exchangers, or by functioning a part of multiple heat source side heat exchangers as condensers Since it is not necessary to perform control to reduce the evaporation capacity by offsetting the evaporation capacity of the heat source side heat exchanger, a wide range of control of the evaporation capacity can be obtained by a single heat source side heat exchanger.

  This makes it possible to unify the heat source side heat exchanger in an air conditioner where unification of the heat source side heat exchanger has not been realized due to the control width limitation of the evaporation capacity control of the heat source side heat exchanger. Therefore, the increase in the number of parts and cost increase caused by installing multiple heat source side heat exchangers in the conventional air conditioner can be prevented, and some of the multiple heat source side heat exchangers can be condensed. When the evaporation capacity is reduced by functioning as a heat exchanger, the amount of refrigerant compressed in the compression mechanism increases by the amount of refrigerant condensed in the heat source side heat exchanger, and the air conditioning load of the entire plurality of usage side refrigerant circuits is small It is possible to solve the problem that the COP in the operating condition is deteriorated.

1 is a schematic refrigerant circuit diagram of an air-conditioning apparatus according to an embodiment of the present invention. It is a figure which shows the schematic structure of the whole heat source side heat exchanger. FIG. 3 is an enlarged view of a portion C in FIG. 2, illustrating a schematic structure of a lower part of a heat source side heat exchanger. It is a schematic refrigerant circuit diagram explaining the operation | movement in the heating operation mode of an air conditioning apparatus. It is a schematic refrigerant circuit diagram explaining the operation | movement in the air_conditionaing | cooling operation mode of an air conditioning apparatus. It is a schematic refrigerant circuit diagram explaining the operation | movement in the heating / cooling simultaneous operation mode (evaporation load) of an air conditioning apparatus. It is a schematic refrigerant circuit diagram explaining the operation | movement in the heating / cooling simultaneous operation mode (condensation load) of an air conditioning apparatus. FIG. 6 is a schematic refrigerant circuit diagram of an air conditioner according to Modification 1. It is a schematic refrigerant circuit diagram explaining the operation | movement in the heating operation mode of the air conditioning apparatus of the modification 1. It is a schematic refrigerant circuit diagram explaining the operation | movement in the air_conditionaing | cooling operation mode of the air conditioning apparatus of the modification 1. FIG. 6 is a schematic refrigerant circuit diagram of an air-conditioning apparatus according to Modification 2. FIG. 10 is a schematic refrigerant circuit diagram of an air-conditioning apparatus according to Modification 3. FIG. 10 is a schematic refrigerant circuit diagram of an air conditioner according to Modification 4. FIG. 10 is a schematic refrigerant circuit diagram of an air conditioner according to Modification 4. FIG. 10 is a schematic refrigerant circuit diagram of an air conditioner according to Modification 4. FIG. 10 is a schematic refrigerant circuit diagram of an air conditioner according to Modification 4.

Explanation of symbols

1 Air conditioning equipment (refrigeration equipment)
12 refrigerant circuit 12a, 12b, 12c use side refrigerant circuit 12d heat source side refrigerant circuit 21 compression mechanism 23 heat source side heat exchanger (evaporator)
24 Heat source side expansion valve (expansion valve)
31, 41, 51 Usage side expansion valve 32, 42, 52 Usage side heat exchanger (condenser)
101 First oil return circuit (oil return circuit)
101b On-off valve 111 Pressurizing circuit 121 Cooler 122 Cooling circuit 131, 141 Pressure reducing mechanism (differential pressure increasing mechanism)
151 Pump mechanism (Differential pressure increasing mechanism)
161 Ejector mechanism (Differential pressure increasing mechanism)

Hereinafter, embodiments of an air-conditioning apparatus according to the present invention will be described based on the drawings.
(1) Configuration of Air Conditioner FIG. 1 is a schematic refrigerant circuit diagram of an air conditioner 1 according to an embodiment of the present invention. The air conditioner 1 is an apparatus used for indoor air conditioning such as a building by performing a vapor compression refrigeration cycle operation.
The air conditioner 1 mainly includes one heat source unit 2, a plurality (three in this embodiment) of usage units 3, 4, and 5, and connection units connected to the usage units 3, 4, and 5. 6, 7, 8, and refrigerant communication pipes 9, 10, 11 connecting the heat source unit 2 and the utilization units 3, 4, 5 through the connection units 6, 7, 8, for example, an air conditioner Cooling and heating simultaneous operation is possible according to the requirements of the indoor air conditioning space where the use units 3, 4, and 5 are installed, such as performing cooling operation for the space and heating operation for the other air-conditioned space. It is comprised so that it may become. That is, the vapor compression refrigerant circuit 12 of the air conditioner 1 of the present embodiment includes a heat source unit 2, utilization units 3, 4, 5, connection units 6, 7, 8, refrigerant communication pipes 9, 10, 11 is connected.

In the present embodiment, a combination of refrigerating machine oil and refrigerant that do not separate into two layers in a temperature range of −20 ° C. or lower is used for the refrigerant circuit 12 of the air conditioner 1. As a combination of such a refrigerant and refrigerating machine oil, for example, there is a combination of R410A and an ether oil such as polyvinyl ether (PVE). Here, the combination of refrigerating machine oil and refrigerant that do not separate into two layers in the temperature range of −20 ° C. or lower is used for the following reason.
First, paying attention to the fact that the maximum value of the evaporation temperature of the refrigerant when the heat source side heat exchanger 23 (described later) of the heat source unit 2 functions as an evaporator is 30 ° C., at least the maximum value of this evaporation temperature (that is, the maximum value) In the temperature range of 30 ° C. or lower, the refrigerating machine oil and the refrigerant accumulated in the heat source side heat exchanger 23 are not separated into two layers, so that the refrigerating machine oil together with the refrigerant from the lower part of the heat source side heat exchanger 23 This is because it can be extracted and returned to the compression mechanism 21 (described later) of the heat source unit 2.
More preferably, paying attention to the minimum value of the evaporation temperature of the refrigerant when the heat source side heat exchanger 23 (described later) of the heat source unit 2 functions as an evaporator, the heat source is in a temperature range below the minimum value of the evaporation temperature. By preventing the refrigerating machine oil and the refrigerant accumulated in the side heat exchanger 23 from separating into two layers, the refrigerating machine oil is extracted together with the refrigerant from the lower part of the heat source side heat exchanger 23, and the compression mechanism 21 ( This is because it is desirable to be able to return to (described later). The minimum evaporating temperature is −5 ° C. when water is used as the heat source of the heat source side heat exchanger 23, and −15 when air is used as the heat source of the heat source side heat exchanger 23. It is -20 degreeC when using brine (for example, what contains 40-50 wt% of ethylene glycol) as a heat source of the heat source side heat exchanger 23.

<Usage unit>
The use units 3, 4, and 5 are installed by being embedded or suspended in an indoor ceiling of a building or the like, or are mounted on a wall surface of an indoor wall. The utilization units 3, 4, 5 are connected to the heat source unit 2 via the refrigerant communication pipes 9, 10, 11 and the connection units 6, 7, 8 and constitute a part of the refrigerant circuit 12.
Next, the configuration of the usage units 3, 4, and 5 will be described. Since the usage unit 3 and the usage units 4 and 5 have the same configuration, only the configuration of the usage unit 3 will be described here, and for the configuration of the usage units 4 and 5, each part of the usage unit 3 will be described. The reference numbers 40 and 50 are used instead of the reference numbers 30 and the description of each part is omitted.
The usage unit 3 mainly constitutes a part of the refrigerant circuit 12 and includes usage-side refrigerant circuits 12a (in the usage units 4 and 5, usage-side refrigerant circuits 12b and 12c, respectively). The use side refrigerant circuit 12 a mainly includes a use side expansion valve 31 and a use side heat exchanger 32. In the present embodiment, the use side expansion valve 31 is an electric expansion valve connected to the liquid side of the use side heat exchanger 32 in order to adjust the flow rate of the refrigerant flowing in the use side refrigerant circuit 12a. In the present embodiment, the use side heat exchanger 32 is a cross-fin type fin-and-tube heat exchanger configured by heat transfer tubes and a large number of fins, and performs heat exchange between the refrigerant and the indoor air. Equipment. In the present embodiment, the utilization unit 3 includes a blower fan (not shown) for supplying indoor air as supply air after inhaling indoor air into the unit and exchanging heat. It is possible to exchange heat with the refrigerant flowing through the side heat exchanger 32.

  The utilization unit 3 is provided with various sensors. A liquid side temperature sensor 33 for detecting the temperature of the liquid refrigerant is provided on the liquid side of the use side heat exchanger 32, and a gas side temperature for detecting the temperature of the gas refrigerant is provided on the gas side of the use side heat exchanger 32. A sensor 34 is provided. Furthermore, the utilization unit 3 is provided with an RA intake temperature sensor 35 for detecting the temperature of indoor air sucked into the unit. In addition, the usage unit 3 includes a usage-side control unit 36 that controls the operation of each unit constituting the usage unit 3. And the use side control part 36 has a microcomputer and memory provided in order to control the use unit 3, and exchanges a control signal etc. between remote controls (not shown), Control signals and the like can be exchanged with the heat source unit 2.

<Heat source unit>
The heat source unit 2 is installed on a rooftop of a building or the like, and is connected to the usage units 3, 4, 5 via the refrigerant communication pipes 9, 10, 11. A refrigerant circuit 12 is configured.
Next, the configuration of the heat source unit 2 will be described. The heat source unit 2 mainly constitutes a part of the refrigerant circuit 12 and includes a heat source side refrigerant circuit 12d. The heat source side refrigerant circuit 10d mainly includes a compression mechanism 21, a first switching mechanism 22, a heat source side heat exchanger 23,
Heat source side expansion valve 24, receiver 25, second switching mechanism 26, liquid side closing valve 27, high pressure gas side closing valve 28, low pressure gas side closing valve 29, first oil return circuit 101, booster A pressure circuit 111, a cooler 121, and a cooling circuit 122 are provided.
The compression mechanism 21 mainly includes a compressor 21a, an oil separator 21b connected to the discharge side of the compressor 21a, and a second oil return circuit 21d that connects the oil separator 21b and the suction pipe 21c of the compressor 21a. And have. In the present embodiment, the compressor 21a is a positive displacement compressor capable of changing an operation capacity by inverter control. The oil separator 21b is a container for separating refrigeration oil accompanying the high-pressure gas refrigerant compressed and discharged in the compressor 21a. The second oil return circuit 21d is a circuit for returning the refrigeration oil separated in the oil separator 21b to the compressor 21a. The second oil return circuit 21d mainly includes an oil return pipe 21e that connects the oil separator 21b and the suction pipe 21c of the compressor 21a, and a high pressure separated in the oil separator 21b that is connected to the oil return pipe 21e. And a capillary tube 21f for reducing the pressure of the refrigerating machine oil. The capillary tube 21f is a thin tube that depressurizes the high-pressure refrigeration oil separated in the oil separator 21b to the refrigerant pressure on the suction side of the compressor 21a. In the present embodiment, the compression mechanism 21 has only one compressor 21a as a compressor, but is not limited to this, and two or more compressors are connected in parallel according to the number of units connected. It may be what was done.

  The first switching mechanism 22 connects the discharge side of the compression mechanism 21 and the gas side of the heat source side heat exchanger 23 when the heat source side heat exchanger 23 functions as a condenser (hereinafter referred to as a condensation operation state). When the heat source side heat exchanger 23 functions as an evaporator (hereinafter referred to as an evaporation operation state), the heat source is connected so that the suction side of the compression mechanism 21 and the gas side of the heat source side heat exchanger 23 are connected. This is a four-way switching valve capable of switching the refrigerant flow path in the side refrigerant circuit 12d. The first port 22a is connected to the discharge side of the compression mechanism 21, and the second port 22b is a heat source side heat. The third port 22c is connected to the suction side of the compression mechanism 21 and the fourth port 22d is connected to the suction side of the compression mechanism 21 via the capillary tube 91. ing. As described above, the first switching mechanism 22 connects the first port 22a and the second port 22b, and connects the third port 22c and the fourth port 22d (corresponding to the condensing operation state, FIG. 1), or the second port 22b and the third port 22c are connected, and the first port 22c and the fourth port 22d are connected (corresponding to the evaporation operation state, FIG. 1). (Refer to the broken line of the first switching mechanism 22).

  The heat source side heat exchanger 23 is a heat exchanger that can function as a refrigerant evaporator and a refrigerant condenser. In the present embodiment, the heat source side heat exchanger 23 is a plate heat exchanger that exchanges heat with the refrigerant using water as a heat source. . The gas side of the heat source side heat exchanger 23 is connected to the second port 22 b of the first switching mechanism 22, and the liquid side thereof is connected to the heat source side expansion valve 24. As shown in FIG. 2, the heat source side heat exchanger 23 moves up and down between the plate members 23 a by overlapping a plurality of plate members 23 a formed by pressing or the like via packing (not shown). A plurality of flow paths 23b, 23c extending in the direction are formed, and refrigerant and water flow alternately in the plurality of flow paths 23b, 23c (specifically, the refrigerant flows in the flow path 23b, Is configured to be able to exchange heat by flowing through the flow path 23c (see arrows A and B in FIG. 2). The plurality of flow paths 23b communicate with each other at the upper end and the lower end thereof, and are connected to the gas side nozzle 23d and the liquid side nozzle 23e provided at the upper and lower portions of the heat source side heat exchanger 23. ing. The gas side nozzle 23 d is connected to the first switching mechanism 22, and the liquid side nozzle 23 e is connected to the heat source side expansion valve 24. Thereby, when the heat source side heat exchanger 23 functions as an evaporator, the refrigerant flows in from the liquid side nozzle 23e (that is, the lower side) and flows out from the gas side nozzle 23d (that is, the upper side). When the side heat exchanger 23 functions as a condenser, it flows in from the gas side nozzle 23d (that is, the upper side) and flows out from the liquid side nozzle 23e (that is, the lower side) (arrow A in FIG. 2). reference). Further, the plurality of flow paths 23c are in communication with each other at the upper end portion and the lower end portion thereof, and are connected to the water inlet nozzle 23f and the water outlet nozzle 23g provided at the upper and lower portions of the heat source side heat exchanger 23. ing. In addition, in this embodiment, water as a heat source is water inlet nozzle 23f of heat source side heat exchanger 23 through a water pipe (not shown) from a cold water tower facility or a boiler facility installed outside air conditioner 1. After being supplied as supply water CWS and exchanging heat with the refrigerant, it flows out from the water outlet nozzle 23g and is returned to the chilled water tower facility or boiler facility as discharged water CWR. Here, a constant amount of water supplied from the cold water tower equipment or the boiler equipment is supplied regardless of the flow rate of the refrigerant flowing in the heat source side heat exchanger 23.

In this embodiment, the heat source side expansion valve 24 adjusts the flow rate of the refrigerant flowing between the heat source side heat exchanger 23 and the use side refrigerant circuits 12a, 12b, and 12c via the liquid refrigerant communication pipe 9. And is connected to the liquid side of the heat source side heat exchanger 23.
The receiver 25 is a container for temporarily storing the refrigerant flowing between the heat source side heat exchanger 23 and the use side refrigerant circuits 12a, 12b, and 12c. In the present embodiment, the receiver 25 is connected between the heat source side expansion valve 24 and the cooler 121.
The second switching mechanism 26 is used when the heat source unit 2 is used as a heat source unit for a cooling and heating simultaneous machine (see FIGS. 4 to 7), and sends a high-pressure gas refrigerant to the use-side refrigerant circuits 12a, 12b, and 12c ( Hereinafter, in the heating load required operation state), when the discharge side of the compression mechanism 21 and the high-pressure gas side shut-off valve 28 are connected and the heat source unit 2 is used as a heat source unit for a cooling / heating switcher (Modification 1). 8-10, hereinafter referred to as the cooling operation state at the time of cooling / heating switching), when performing the cooling operation, the high pressure gas side closing valve 28 and the suction side of the compression mechanism 21 are connected to each other, This is a four-way switching valve capable of switching the refrigerant flow path in the heat source side refrigerant circuit 12d, the first port 26a is connected to the discharge side of the compression mechanism 21, and the second port 26b is a capillary tube. 92 And is connected to the intake side of the compression mechanism 21, the third port 26c is connected to the intake side of the compression mechanism 21, the fourth port 26d is connected to the high-pressure gas closing valve 28. As described above, the second switching mechanism 26 connects the first port 26a and the second port 26b, and connects the third port 26c and the fourth port 26d (corresponding to the cooling operation state during cooling / heating switching). 1) (refer to the solid line of the second switching mechanism 26 in FIG. 1), the second port 26b and the third port 26c are connected, and the first port 26a and the fourth port 26d are connected (heating load request operation state) Corresponding to (see the broken line of the second switching mechanism 26 in FIG. 1).

The liquid-side closing valve 27, the high-pressure gas-side closing valve 28, and the low-pressure gas-side closing valve 29 are valves provided at connection ports with external devices and pipes (specifically, refrigerant communication pipes 9, 10 and 11). It is. The liquid side closing valve 27 is connected to the cooler 121. The high-pressure gas side closing valve 28 is connected to the fourth port 26 d of the second switching mechanism 26. The low pressure gas side closing valve 29 is connected to the suction side of the compression mechanism 21.
The first oil return circuit 101 is a circuit that returns the refrigeration oil accumulated in the heat source side heat exchanger 23 together with the refrigerant to the compression mechanism 21 when the evaporation operation state, that is, when the heat source side heat exchanger 23 functions as an evaporator. It is. The first oil return circuit 101 mainly includes an oil return pipe 101a connecting the lower part of the heat source side heat exchanger 23 and the compression mechanism 21, an on-off valve 101b connected to the oil return pipe 101a, and a check valve 101c. And a capillary tube 101d. The oil return pipe 101a is provided so that one end can extract the refrigerating machine oil together with the refrigerant from the lower part of the heat source side heat exchanger 23. In the present embodiment, as shown in FIG. It is a pipe that extends to the inside of the flow path 23b through which the refrigerant of the heat source side heat exchanger 23 flows through the pipe of the liquid side nozzle 23e provided in the lower part of the exchanger 23. Here, in the heat source side heat exchanger 23, in order to communicate between the plurality of flow paths 23b, communication holes 23h are provided in each plate member 23a (the same applies to the plurality of flow paths 23c). For this reason, the oil return pipe 101a may be provided so as to penetrate the plurality of flow paths 23b (see the oil return pipe 101a indicated by the broken line in FIG. 3). The other end of the oil return pipe 101a is connected to the suction side of the compression mechanism 21 in this embodiment. In the present embodiment, the on-off valve 101b is connected so that the first oil return circuit 101 can be used as necessary, and is an electromagnetic valve capable of circulating and blocking refrigerant and refrigerating machine oil. The check valve 101c is a valve that only allows refrigerant and refrigerating machine oil to flow through the oil return pipe 101a from the lower part of the heat source side heat exchanger 23 toward the suction side of the compression mechanism 21. The capillary tube 101 d is a thin tube that depressurizes the refrigerant and refrigeration oil extracted from the lower part of the heat source side heat exchanger 23 to the refrigerant pressure on the suction side of the compression mechanism 21.

  In the condensing operation state, that is, when the heat source side heat exchanger 23 functions as a condenser, the pressurizing circuit 111 condenses the high-pressure gas refrigerant compressed in the compression mechanism 21 in the heat source side heat exchanger 23 and becomes a heat source. This is a circuit for joining the refrigerant sent to the use side refrigerant circuits 12a, 12b, 12c after being depressurized in the side expansion valve 24. The pressurizing circuit 111 mainly includes a pressurizing pipe 111a that connects the discharge side of the compression mechanism 21 and the downstream side of the heat source side expansion valve 24 (that is, between the heat source side expansion valve 24 and the liquid side closing valve 27), It has an on-off valve 111b connected to the pressurizing tube 111a, a check valve 111c, and a capillary tube 111d. In the present embodiment, one end of the pressurizing pipe 111 a is connected between the outlet of the oil separator 21 b of the compression mechanism 21 and the first ports 22 a and 26 a of the first and second switching mechanisms 22 and 26. In addition, the other end of the pressurizing pipe 111a is connected between the heat source side expansion valve 24 and the receiver 25 in the present embodiment. In the present embodiment, the on-off valve 111b is connected so that the pressurization circuit 111 can be used as necessary, and is an electromagnetic valve capable of circulating and blocking the refrigerant. The check valve 111 c is a valve that only allows the refrigerant to flow in the pressurizing pipe 111 a from the discharge side of the compression mechanism 21 toward the downstream side of the heat source side expansion valve 24. The capillary tube 111 d is a narrow tube that depressurizes the refrigerant extracted from the discharge side of the compression mechanism 21 to the refrigerant pressure downstream of the heat source side expansion valve 24.

The cooler 121 is condensed in the condensing operation state, that is, when the heat source side heat exchanger 23 functions as a condenser, and after being condensed in the heat source side heat exchanger 23, the cooler 121 is decompressed in the heat source side expansion valve 24 and used. It is a heat exchanger that cools the refrigerant sent to the circuits 12a, 12b, and 12c. The cooler 121 is connected between the receiver 25 and the liquid side closing valve 27 in the present embodiment. In other words, in the pressurizing circuit 111, the pressurizing pipe 111a is connected between the heat source side expansion valve 24 and the cooler 121 so that the high-pressure gas refrigerant merges with the refrigerant depressurized in the heat source side expansion valve 24. It is connected. As the cooler 121, for example, a double-pipe heat exchanger can be used.
The cooling circuit 122 is a part of the refrigerant sent from the heat source side heat exchanger 23 to the use side refrigerant circuits 12a, 12b, and 12c in the condensing operation state, that is, when the heat source side heat exchanger 23 functions as a condenser. The refrigerant branched from the heat source side refrigerant circuit 12d and introduced into the cooler 121 is cooled in the heat source side heat exchanger 23, condensed in the heat source side expansion valve 24 and depressurized in the heat source side refrigerant circuit 12a, 12b, 12c. Thereafter, the circuit is connected to the heat source side refrigerant circuit 12d so as to return to the suction side of the compression mechanism 21. The cooling circuit 122 mainly includes an introduction pipe 122a for introducing a part of the refrigerant sent from the heat source side heat exchanger 23 to the use side refrigerant circuits 12a, 12b, and 12c into the cooler 121, and a cooling connected to the introduction pipe 122a. It has a circuit side expansion valve 122b and a lead-out pipe 122c that returns the refrigerant that has passed through the cooler 121 to the suction side of the compression mechanism 21. In the present embodiment, one end of the introduction pipe 122 a is connected between the receiver 25 and the cooler 121. The other end of the introduction pipe 122a is connected to the inlet of the cooler 121 on the cooling circuit 122 side in this embodiment. In this embodiment, the cooling circuit side expansion valve 122b is connected so that the cooling circuit 122 can be used as necessary, and the electric expansion capable of adjusting the flow rate of the refrigerant flowing through the cooling circuit 122. It is a valve. In the present embodiment, one end of the outlet tube 122c is connected to the outlet of the cooler 121 on the cooling circuit 122 side. In the present embodiment, the other end of the outlet tube 122 c is connected to the suction side of the compression mechanism 21.

  The heat source unit 2 is provided with various sensors. Specifically, the heat source unit 2 includes a suction pressure sensor 93 that detects the suction pressure of the compression mechanism 21, a discharge pressure sensor 94 that detects the discharge pressure of the compression mechanism 21, and the discharge of refrigerant on the discharge side of the compression mechanism 21. A discharge temperature sensor 95 for detecting the temperature and a cooling circuit outlet temperature sensor 96 for detecting the temperature of the refrigerant flowing through the outlet pipe 122c of the cooling circuit 122 are provided. In addition, the heat source unit 2 includes a heat source side control unit 97 that controls the operation of each unit constituting the heat source unit 2. The heat source side control unit 97 includes a microcomputer and a memory provided to control the heat source unit 2, and is connected to the use side control units 36, 46, and 56 of the use units 3, 4, and 5. Control signals and the like can be exchanged between them.

<Connection unit>
The connection units 6, 7, 8 are installed together with the use units 3, 4, 5 inside a building or the like. The connection units 6, 7, 8 are interposed between the utilization units 3, 4, 5 and the heat source unit 2 together with the refrigerant communication pipes 9, 10, 11, and constitute a part of the refrigerant circuit 12. .
Next, the configuration of the connection units 6, 7, and 8 will be described. Since the connection unit 6 and the connection units 7 and 8 have the same configuration, only the configuration of the connection unit 6 will be described here, and for the configuration of the connection units 7 and 8, each part of the connection unit 6 will be described. The reference numbers 70 and 80 are used instead of the reference numbers 60 and the description of each part is omitted.
The connection unit 6 mainly constitutes a part of the refrigerant circuit 12 and includes a connection side refrigerant circuit 12e (in the connection units 7 and 8, connection side refrigerant circuits 12f and 12g, respectively). The connection side refrigerant circuit 12e mainly includes a liquid connection pipe 61, a gas connection pipe 62, a high pressure gas on / off valve 66, and a low pressure gas on / off valve 67. In the present embodiment, the liquid connection pipe 61 connects the liquid refrigerant communication pipe 9 and the use side expansion valve 31 of the use side refrigerant circuit 12a. The gas connection pipe 62 includes a high pressure gas connection pipe 63 connected to the high pressure gas refrigerant communication pipe 10, a low pressure gas connection pipe 64 connected to the low pressure gas refrigerant communication pipe 11, a high pressure gas connection pipe 63, and a low pressure gas connection pipe. And a merging gas connection pipe 65 for merging 64 and 64. The merged gas connection pipe 65 is connected to the gas side of the use side heat exchanger 32 of the use side refrigerant circuit 12a. In the present embodiment, the high-pressure gas on / off valve 66 is connected to the high-pressure gas connection pipe 63 and is an electromagnetic valve capable of circulating and blocking the refrigerant. In this embodiment, the low-pressure gas on-off valve 67 is connected to the low-pressure gas connection pipe 64 and is an electromagnetic valve capable of circulating and blocking the refrigerant. As a result, when the use unit 3 performs the cooling operation, the connection unit 6 closes the high-pressure gas on-off valve 66 and opens the low-pressure gas on-off valve 67, and then connects the liquid through the liquid refrigerant communication pipe 9. The refrigerant flowing into the connection pipe 61 is sent to the use side expansion valve 31 of the use side refrigerant circuit 12a, decompressed by the use side expansion valve 31 and evaporated in the use side heat exchanger 32, and then the combined gas connection pipe 65 and the low pressure gas. It can function to return to the low-pressure gas refrigerant communication pipe 11 through the connection pipe 64. In addition, when the usage unit 3 performs the heating operation, the connection unit 6 closes the low pressure gas on / off valve 67 and opens the high pressure gas on / off valve 66 so that the high pressure gas refrigerant communication pipe 10 is used. The refrigerant flowing into the gas connection pipe 63 and the combined gas connection pipe 65 is sent to the gas side of the use side heat exchanger 32 of the use side refrigerant circuit 12a, condensed in the use side heat exchanger 32, and decompressed by the use side expansion valve 31. After that, it can function to return to the liquid refrigerant communication pipe 9 through the liquid connection pipe 61. In addition, the connection unit 6 includes a connection side control unit 68 that controls the operation of each unit constituting the connection unit 6. The connection side control unit 68 includes a microcomputer and a memory provided for controlling the connection unit 6, and exchanges control signals and the like with the use side control unit 36 of the use unit 3. Can be done.

As described above, the use-side refrigerant circuits 12a, 12b, and 12c, the heat source-side refrigerant circuit 12d, the refrigerant communication pipes 9, 10, and 11, and the connection-side refrigerant circuits 12e, 12f, and 12g are connected, and air conditioning. A refrigerant circuit 12 of the device 1 is configured. And in the air conditioning apparatus 1 of this embodiment, it becomes possible to perform what is called simultaneous cooling and heating operation, such as the utilization unit 5 performing heating operation, for example, while the utilization units 3 and 4 perform cooling operation. Yes.
And in the air conditioning apparatus 1 of this embodiment, when making the heat source side heat exchanger 23 function as an evaporator as mentioned later, by using the 1st oil return circuit 101, of the heat source side heat exchanger 23 is used. The control range when the evaporation capacity is controlled by the heat source side expansion valve 24 is expanded, and a wide control range of the evaporation capacity can be obtained by the single heat source side heat exchanger 23. Further, in the air conditioner 1, as will be described later, when the heat source side heat exchanger 23 is caused to function as a condenser, the condensing capacity of the heat source side heat exchanger 23 is obtained by using the pressurizing circuit 111 and the cooler 121. Is controlled by the heat source side expansion valve 24, and a single heat source side heat exchanger 23 can obtain a wide control range of the condensing capacity. Thereby, in the air conditioning apparatus 1 of this embodiment, unification of the heat-source side heat exchanger provided in multiple units in the conventional air conditioning apparatus is implement | achieved.

(2) Operation | movement of an air conditioning apparatus Next, operation | movement of the air conditioning apparatus 1 of this embodiment is demonstrated.
The operation mode of the air conditioner 1 of the present embodiment includes a heating operation mode in which all of the usage units 3, 4, and 5 perform a heating operation according to the air conditioning load of each usage unit 3, 4, and 5, and the usage unit 3, 4 and 5 can be divided into a cooling operation mode in which the cooling operation is performed, and a cooling and heating simultaneous operation mode in which a part of the usage units 3, 4 and 5 performs the cooling operation while another usage unit performs the heating operation. . In the cooling / heating simultaneous operation mode, when the heat source side heat exchanger 23 of the heat source unit 2 is operated as an evaporator by the air conditioning load of the entire usage units 3, 4 and 5 (evaporation operation state) The operation mode can be divided into a case where the heat source side heat exchanger 23 of the heat source unit 2 is operated as a condenser (condensation operation state).
Hereinafter, the operation | movement in the four operation modes of the air conditioning apparatus 1 is demonstrated.

<Heating operation mode>
When all the usage units 3, 4, and 5 are heated, the refrigerant circuit 12 of the air conditioner 1 is configured as shown in FIG. 4 (the refrigerant flow is attached to the refrigerant circuit 12 of FIG. 4). (See the arrow that appears.) Specifically, in the heat source side refrigerant circuit 12d of the heat source unit 2, the first switching mechanism 22 is switched to the evaporation operation state (the state indicated by the broken line of the first switching mechanism 22 in FIG. 4), and the second switching mechanism. 26 is switched to the heating load required operation state (the state indicated by the broken line of the second switching mechanism 26 in FIG. 4), thereby causing the heat source side heat exchanger 23 to function as an evaporator and through the high-pressure gas refrigerant communication pipe 10. The high-pressure gas refrigerant compressed and discharged by the compression mechanism 21 can be supplied to the use units 3, 4, and 5. Moreover, the opening degree of the heat source side expansion valve 24 is adjusted so as to depressurize the refrigerant. The on-off valve 111b of the pressurizing circuit 111 and the cooling circuit side expansion valve 122b of the cooling circuit 122 are closed, and a high-pressure gas refrigerant is combined with the refrigerant flowing between the heat source side expansion valve 24 and the receiver 25. The supply of the cold heat source to the cooler 121 is shut off, and the refrigerant flowing between the receiver 25 and the utilization units 3, 4, 5 is not cooled. In the connection units 6, 7, 8, the use side heat exchangers of the use units 3, 4, 5 are opened by closing the low pressure gas on / off valves 67, 77, 87 and opening the high pressure gas on / off valves 66, 76, 86. 32, 42 and 52 are in a state of functioning as a condenser. In the usage units 3, 4, and 5, the usage side expansion valves 31, 41, 51 are, for example, the degree of supercooling of the usage side heat exchangers 32, 42, 52 (specifically, the liquid side temperature sensors 33, 43). , 53 based on the refrigerant temperature detected by the gas side temperature sensors 34, 44, 54 and the refrigerant temperature detected by the gas side temperature sensors 34, 44, 54). Has been.

In such a configuration of the refrigerant circuit 12, the high-pressure gas refrigerant compressed and discharged by the compressor 21a of the compression mechanism 21 is separated from most of the refrigerating machine oil accompanying the high-pressure gas refrigerant in the oil separator 21b. Then, it is sent to the second switching mechanism 26. The refrigerating machine oil separated in the oil separator 21b is returned to the suction side of the compressor 21a through the second oil return circuit 21d. The high-pressure gas refrigerant sent to the second switching mechanism 26 is sent to the high-pressure gas refrigerant communication pipe 10 through the first port 26 a and the fourth port 26 d of the second switching mechanism 26 and the high-pressure gas side closing valve 28.
The high-pressure gas refrigerant sent to the high-pressure gas refrigerant communication pipe 10 is branched into three and sent to the high-pressure gas connection pipes 63, 73, 83 of the connection units 6, 7, 8. The high-pressure gas refrigerant sent to the high-pressure gas connection pipes 63, 73, 83 of the connection units 6, 7, 8 passes through the high-pressure gas on / off valves 66, 76, 86 and the merged gas connection pipes 65, 75, 85. It is sent to 3, 4, and 5 utilization side heat exchangers 32, 42, and 52.

The high-pressure gas refrigerant sent to the usage-side heat exchangers 32, 42, 52 exchanges heat with indoor air in the usage-side heat exchangers 32, 42, 52 of the usage units 3, 4, 5. Condensed by. On the other hand, indoor air is heated and supplied indoors. The refrigerant condensed in the use side heat exchangers 32, 42, 52 is sent to the liquid connection pipes 61, 71, 81 of the connection units 6, 7, 8 after passing through the use side expansion valves 31, 41, 51. .
The refrigerant sent to the liquid connection pipes 61, 71, 81 is sent to the liquid refrigerant communication pipe 9 and merges.
Then, the refrigerant sent to and joined to the liquid refrigerant communication pipe 9 is sent to the receiver 25 through the liquid side closing valve 27 and the cooler 121 of the heat source unit 2. The refrigerant sent to the receiver 25 is temporarily stored in the receiver 25 and then decompressed by the heat source side expansion valve 24. The refrigerant depressurized by the heat source side expansion valve 24 is evaporated by exchanging heat with water as a heat source in the heat source side heat exchanger 23 to become a low pressure gas refrigerant, and is sent to the first switching mechanism 22. It is done. The low-pressure gas refrigerant sent to the first switching mechanism 22 is returned to the suction side of the compression mechanism 21 through the second port 22b and the third port 22c of the first switching mechanism 22. In this way, the operation in the heating operation mode is performed.

  At this time, the heating load of each utilization unit 3, 4, and 5 may become very small. In such a case, the refrigerant evaporation capacity in the heat source side heat exchanger 23 of the heat source unit 2 is reduced, and the heating load of the entire usage units 3, 4, 5 (that is, the usage side heat exchangers 32, 42, 52) (condensation load of 52). For this reason, control is performed to reduce the evaporation amount of the refrigerant in the heat source side heat exchanger 23 by performing control to reduce the opening degree of the heat source side expansion valve 24. When the control for reducing the opening degree of the heat source side expansion valve 24 is performed, the liquid level of the refrigerant in the heat source side heat exchanger 23 is lowered. Then, like the heat source side heat exchanger 23 of this embodiment, when functioning as a refrigerant evaporator, the heat exchanger is configured such that the refrigerant flows in from the lower side and flows out from the upper side (FIGS. 2 and 2). 3), the refrigerating machine oil becomes difficult to be discharged together with the evaporated refrigerant, and the refrigerating machine oil is easily accumulated.

  However, in the air conditioner 1 of the present embodiment, a combination of refrigerating machine oil and refrigerant that does not separate into two layers in a temperature range of 30 ° C. or lower (more preferably, lower than the minimum value of the evaporation temperature) is used (that is, the heat source side). When the heat exchanger functions as an evaporator, a combination of refrigerating machine oil and refrigerant that do not separate into two layers in the heat source side heat exchanger is used, and a first oil return circuit 101 is provided. The on-off valve 101b of the first oil return circuit 101 is opened in the heating operation mode (that is, when the first switching mechanism 22 is in the evaporation operation state), and passes through the oil return pipe 101a. The refrigeration oil can be extracted from the heat source side heat exchanger 23 together with the refrigerant from the lower part of the heat source side heat exchanger 23 and returned to the compression mechanism 21. For this reason, by performing control to reduce the opening degree of the heat source side expansion valve 24, the liquid level of the refrigerant in the heat source side heat exchanger 23 is lowered, and it is difficult for the refrigerating machine oil to be discharged together with the evaporated refrigerant. Regardless of the state, the accumulation of the refrigerating machine oil in the heat source side heat exchanger 23 can be prevented.

  Note that if the on-off valve 101b is opened when the heat source side heat exchanger 23 functions as a condenser, a part of the refrigerant condensed in the heat source side heat exchanger 23 is returned to the compression mechanism 21. Since the amount of refrigerant sent to the use-side refrigerant circuits 12a, 12b, and 12c decreases, the first switching mechanism 22 is closed when the first switching mechanism 22 is in the condensation operation state, and the first switching mechanism 22 is in the evaporation operation state. It is desirable to be able to open it when Further, when the first switching mechanism 22 is in the evaporation operation state, the liquid level of the refrigerant in the heat source side heat exchanger 23 is lowered by performing control to reduce the opening degree of the heat source side expansion valve 24. Alternatively, it may be opened only when the refrigerating machine oil is accompanied by the evaporated refrigerant and is not easily discharged. For example, as a condition for opening the on-off valve 101b, in addition to the first switching mechanism 22 being in the evaporation operation state, it can be added that the heat source side expansion valve 24 is not more than a predetermined opening degree. This predetermined opening degree is an experiment of the opening degree of the heat source side expansion valve 24 in which the refrigerant level in the heat source side heat exchanger 23 is lowered and the refrigerant oil is hardly discharged together with the evaporated refrigerant. And is determined based on the experimentally found opening.

<Cooling operation mode>
When all the use units 3, 4, and 5 are in cooling operation, the refrigerant circuit 12 of the air conditioner 1 is configured as shown in FIG. 5 (the refrigerant flow is attached to the refrigerant circuit 12 in FIG. 5). (See the arrow that appears.) Specifically, in the heat source side refrigerant circuit 12d of the heat source unit 2, the first switching mechanism 22 is switched to the condensation operation state (the state indicated by the solid line of the first switching mechanism 22 in FIG. 5), thereby The heat exchanger 23 is made to function as a condenser. The heat source side expansion valve 24 is in an opened state. The on-off valve 101b of the first oil return circuit 101 is closed so that the operation of extracting the refrigerating machine oil together with the refrigerant from the lower part of the heat source side heat exchanger 23 and returning it to the compression mechanism 21 is not performed. In the connection units 6, 7, 8, the use side heat exchangers of the use units 3, 4, 5 are opened by closing the high pressure gas on / off valves 66, 76, 86 and opening the low pressure gas on / off valves 67, 77, 87. 32, 42, 52 function as an evaporator, and the use side heat exchangers 32, 42, 52 of the use units 3, 4, 5 and the suction side of the compression mechanism 21 of the heat source unit 2 are connected to the low pressure gas refrigerant communication pipe 11. It is in a state of being connected through. In the usage units 3, 4, and 5, the usage side expansion valves 31, 41, 51 are, for example, the degree of superheat (specifically, the liquid side temperature sensors 33, 43, The opening degree is adjusted according to the cooling load of each usage unit, for example, the opening degree is adjusted based on the temperature difference between the refrigerant temperature detected by 53 and the refrigerant temperature detected by the gas side temperature sensors 34, 44, 54). ing.

  In such a configuration of the refrigerant circuit 12, the high-pressure gas refrigerant compressed and discharged by the compressor 21a of the compression mechanism 21 is separated from most of the refrigerating machine oil accompanying the high-pressure gas refrigerant in the oil separator 21b. And sent to the first switching mechanism 22. The refrigerating machine oil separated in the oil separator 21b is returned to the suction side of the compressor 21a through the second oil return circuit 21d. The high-pressure gas refrigerant sent to the first switching mechanism 22 is sent to the heat source side heat exchanger 23 through the first port 22 a and the second port 22 b of the first switching mechanism 22. The high-pressure gas refrigerant sent to the heat source side heat exchanger 23 is condensed by exchanging heat with water as a heat source in the heat source side heat exchanger 23. The refrigerant condensed in the heat source side heat exchanger 23 passes through the heat source side expansion valve 24, and then the high pressure gas refrigerant compressed and discharged by the compression mechanism 21 through the pressurizing circuit 111 is joined (for details). Sent to the receiver 25). The refrigerant sent to the receiver 25 is temporarily stored in the receiver 25 and then sent to the cooler 121. Then, the refrigerant sent to the cooler 121 is cooled by exchanging heat with the refrigerant flowing through the cooling circuit 122 (details will be described later). Then, the refrigerant cooled in the cooler 121 is sent to the liquid refrigerant communication pipe 9 through the liquid side closing valve 27.

Then, the refrigerant sent to the liquid refrigerant communication pipe 9 is branched into three and sent to the liquid connection pipes 61, 71, 81 of the connection units 6, 7, 8. The refrigerant sent to the liquid connection pipes 61, 71, 81 of the connection units 6, 7, 8 is sent to the use side expansion valves 31, 41, 51 of the use units 3, 4, 5.
The refrigerant sent to the use side expansion valves 31, 41, 51 is decompressed by the use side expansion valves 31, 41, 51, and then exchanges heat with indoor air in the use side heat exchangers 32, 42, 52. Is evaporated to become a low-pressure gas refrigerant. On the other hand, indoor air is cooled and supplied indoors. Then, the low-pressure gas refrigerant is sent to the merged gas connection pipes 65, 75, 85 of the connection units 6, 7, 8.
The low-pressure gas refrigerant sent to the merged gas connection pipes 65, 75, 85 is sent to the low-pressure gas refrigerant communication pipe 11 through the low-pressure gas on / off valves 67, 77, 87 and the low-pressure gas connection pipes 64, 74, 84. Be merged.

Then, the low-pressure gas refrigerant sent to the low-pressure gas refrigerant communication pipe 11 and merged is returned to the suction side of the compression mechanism 21 through the low-pressure gas side shut-off valve 29. In this way, the operation in the cooling operation mode is performed.
At this time, the cooling load of each utilization unit 3, 4, and 5 may become very small. In such a case, the refrigerant condensing capacity in the heat source side heat exchanger 23 of the heat source unit 2 is reduced, and the cooling load of the entire usage units 3, 4, 5 (that is, the usage side heat exchangers 32, 42, (Evaporation load of 52). For this reason, control is performed to reduce the amount of refrigerant condensed in the heat source side heat exchanger 23 by performing control to reduce the opening degree of the heat source side expansion valve 24. When control is performed to reduce the opening degree of the heat source side expansion valve 24, the amount of liquid refrigerant that accumulates in the heat source side heat exchanger 23 increases and the substantial heat transfer area decreases, thereby condensing capacity. Get smaller. However, when the control to reduce the opening degree of the heat source side expansion valve 24 is performed, the downstream side of the heat source side expansion valve 24 (specifically, between the heat source side expansion valve 24 and the use side refrigerant circuits 12a, 12b, 12c). ) Refrigerant pressure tends to decrease and is not stable, and it is difficult to stably perform control to reduce the condensation capacity of the heat source side refrigerant circuit 12d.

  In contrast, in the air conditioning apparatus 1 of the present embodiment, the high-pressure gas refrigerant compressed and discharged by the compression mechanism 21 is decompressed by the heat source side expansion valve 24 and sent to the use side refrigerant circuits 12a, 12b, and 12c. A pressurizing circuit 111 that joins the refrigerant to be produced is provided. The on-off valve 111b of the pressurizing circuit 111 is opened when in the cooling operation mode (that is, when the first switching mechanism 22 is in the condensing operation state), and is compressed through the pressurizing pipe 111a. The discharge side can be joined to the downstream side of the heat source side expansion valve 24. For this reason, while controlling the opening degree of the heat source side expansion valve 24 to be small, the high pressure gas refrigerant is joined to the downstream side of the heat source side expansion valve 24 through the pressurization circuit 111, thereby downstream of the heat source side expansion valve 24. The pressure of the refrigerant on the side can be increased. However, the refrigerant sent to the use-side refrigerant circuits 12a, 12b, and 12c when the high-pressure gas refrigerant is merged only by joining the high-pressure gas refrigerant to the downstream side of the heat source side expansion valve 24 through the pressurization circuit 111. Becomes a gas-liquid two-phase flow with a large gas fraction, and when the refrigerant is branched from the liquid refrigerant communication pipe 9 to each of the usage side refrigerant circuits 12a, 12b, 12c, between the usage side refrigerant circuits 12a, 12b, 12c. Will cause drift.

  On the other hand, in the air conditioning apparatus 1 of the present embodiment, the cooler 121 is further provided on the downstream side of the heat source side expansion valve 24. For this reason, while controlling the opening degree of the heat source side expansion valve 24 to be small, the high pressure gas refrigerant is joined to the downstream side of the heat source side expansion valve 24 through the pressurization circuit 111, thereby downstream of the heat source side expansion valve 24. Gas refrigerant is controlled because the refrigerant that is decompressed by the heat source side expansion valve 24 and sent to the use side refrigerant circuits 12a, 12b, and 12c is cooled by the cooler 121. Therefore, it is not necessary to send a gas-liquid two-phase flow refrigerant having a large gas fraction to the use-side refrigerant circuits 12a, 12b, and 12c. Moreover, in the air conditioning apparatus 1 of this embodiment, since the pressurization pipe | tube 111a is connected between the heat source side expansion valve 24 and the receiver 25, it is high-pressure gas to the refrigerant | coolant downstream of the heat source side expansion valve 24. The refrigerant merges, and the refrigerant whose temperature has increased due to the merge of the high-pressure gas refrigerant is cooled by the cooler 121. For this reason, it is not necessary to use a low-temperature cold heat source as a cold heat source for cooling the refrigerant in the cooler 121, and a relatively high-temperature cold heat source can be used. Moreover, in the air conditioner 1 of the present embodiment, the cooling circuit 122 is provided, and a part of the refrigerant sent from the heat source side heat exchanger 23 to the use side refrigerant circuits 12a, 12b, 12c is supplied to the compression mechanism 21. Since the pressure is reduced to a refrigerant pressure that can be returned to the suction side, and this refrigerant is used as a cooling source of the cooler 121, the refrigerant is reduced in pressure at the heat source side expansion valve 24 and sent to the use side refrigerant circuits 12a, 12b, 12c. A cooling source having a temperature sufficiently lower than the temperature of the refrigerant can be obtained. For this reason, it is possible to cool the refrigerant that is decompressed in the heat source side expansion valve 24 and sent to the use side refrigerant circuits 12a, 12b, and 12c to a supercooled state. The cooling circuit side expansion valve 122b of the cooling circuit 122 is, for example, adjusted to the degree of superheat of the cooler 121 (calculated from the refrigerant temperature detected by the cooling circuit outlet temperature sensor 96 provided in the outlet pipe 122c of the cooling circuit 122). The opening degree is adjusted according to the flow rate and temperature of the refrigerant sent from the downstream side of the heat source side expansion valve 24 to the use side refrigerant circuits 12a, 12b, and 12c.

<Cooling and heating simultaneous operation mode (evaporation load)>
Of the usage units 3, 4, 5, for example, the cooling operation of the usage unit 3, and the heating operation of the usage units 4, 5 are performed simultaneously. Accordingly, the operation when the heat source side heat exchanger 23 of the heat source unit 2 is operated while functioning as an evaporator (evaporation operation state) will be described. At this time, the refrigerant circuit 12 of the air-conditioning apparatus 1 is configured as shown in FIG. 6 (see the arrows attached to the refrigerant circuit 12 in FIG. 6 for the refrigerant flow). Specifically, in the heat source side refrigerant circuit 12d of the heat source unit 2, the first switching mechanism 22 is in the evaporation operation state (indicated by the broken line of the first switching mechanism 22 in FIG. 6), as in the heating operation mode described above. State), and the second switching mechanism 26 is switched to the heating load request operation state (the state indicated by the broken line of the second switching mechanism 26 in FIG. 6), thereby causing the heat source side heat exchanger 23 to function as an evaporator. At the same time, the high-pressure gas refrigerant compressed and discharged by the compression mechanism 21 can be supplied to the utilization units 4 and 5 through the high-pressure gas refrigerant communication pipe 10. Moreover, the opening degree of the heat source side expansion valve 24 is adjusted so as to depressurize the refrigerant. The on-off valve 111b of the pressurizing circuit 111 and the cooling circuit side expansion valve 122b of the cooling circuit 122 are closed, and a high-pressure gas refrigerant is combined with the refrigerant flowing between the heat source side expansion valve 24 and the receiver 25. The supply of the cold heat source to the cooler 121 is shut off, and the refrigerant flowing between the receiver 25 and the utilization units 3, 4, 5 is not cooled. In the connection unit 6, by closing the high pressure gas on / off valve 66 and opening the low pressure gas on / off valve 67, the usage side heat exchanger 32 of the usage unit 3 functions as an evaporator and the usage side heat of the usage unit 3 is also used. The exchanger 32 and the suction side of the compression mechanism 21 of the heat source unit 2 are connected via the low-pressure gas refrigerant communication pipe 11. In the usage unit 3, the usage-side expansion valve 31 is detected by, for example, the degree of superheat of the usage-side heat exchanger 32 (specifically, the refrigerant temperature detected by the liquid side temperature sensor 33 and the gas side temperature sensor 34). The degree of opening is adjusted according to the cooling load of the utilization unit, for example, the degree of opening is adjusted based on the temperature difference from the refrigerant temperature. In the connection units 7 and 8, the use side heat exchangers 42 and 52 of the use units 4 and 5 function as a condenser by closing the low pressure gas on / off valves 77 and 87 and opening the high pressure gas on / off valves 76 and 86. I try to let them. In the usage units 4 and 5, the usage side expansion valves 41 and 51 include, for example, the degree of supercooling of the usage side heat exchangers 42 and 52 (specifically, the refrigerant temperature detected by the liquid side temperature sensors 43 and 53). And the opening degree is adjusted based on the heating load of each usage unit, for example, the opening degree is adjusted based on the temperature difference between the refrigerant temperature detected by the gas side temperature sensors 44 and 54).

In such a configuration of the refrigerant circuit 12, the high-pressure gas refrigerant compressed and discharged by the compressor 21a of the compression mechanism 21 is separated from most of the refrigerating machine oil accompanying the high-pressure gas refrigerant in the oil separator 21b. Then, it is sent to the second switching mechanism 26. The refrigerating machine oil separated in the oil separator 21b is returned to the suction side of the compressor 21a through the second oil return circuit 21d. The high-pressure gas refrigerant sent to the second switching mechanism 26 is sent to the high-pressure gas refrigerant communication pipe 10 through the first port 26 a and the fourth port 26 d of the second switching mechanism 26 and the high-pressure gas side closing valve 28. .
The high-pressure gas refrigerant sent to the high-pressure gas refrigerant communication pipe 10 is branched into two and sent to the high-pressure gas connection pipes 73 and 83 of the connection units 7 and 8. The high-pressure gas refrigerant sent to the high-pressure gas connection pipes 73, 83 of the connection units 7, 8 passes through the high-pressure gas on / off valves 76, 86 and the merged gas connection pipes 75, 85. 42 and 52.

The high-pressure gas refrigerant sent to the use side heat exchangers 42 and 52 is condensed by exchanging heat with indoor air in the use side heat exchangers 42 and 52 of the use units 4 and 5. On the other hand, indoor air is heated and supplied indoors. The refrigerant condensed in the use side heat exchangers 42 and 52 passes through the use side expansion valves 41 and 51, and then is sent to the liquid connection pipes 71 and 81 of the connection units 7 and 8.
Then, the refrigerant sent to the liquid connection pipes 71 and 81 is sent to the liquid refrigerant communication pipe 9 and merges.
Then, a part of the refrigerant sent to and joined to the liquid refrigerant communication pipe 9 is sent to the liquid connection pipe 61 of the connection unit 6. Then, the refrigerant sent to the liquid connection pipe 61 of the connection unit 6 is sent to the use side expansion valve 31 of the use unit 3.

The refrigerant sent to the use-side expansion valve 31 is decompressed by the use-side expansion valve 31 and then evaporated by exchanging heat with indoor air in the use-side heat exchanger 32, and the low-pressure gas refrigerant. Become. On the other hand, indoor air is cooled and supplied indoors. Then, the low-pressure gas refrigerant is sent to the merged gas connection pipe 65 of the connection unit 6.
The low-pressure gas refrigerant sent to the merged gas connection pipe 65 is sent to and merged with the low-pressure gas refrigerant communication pipe 11 through the low-pressure gas on-off valve 67 and the low-pressure gas connection pipe 64.
Then, the low-pressure gas refrigerant sent to the low-pressure gas refrigerant communication pipe 11 is returned to the suction side of the compression mechanism 21 through the low-pressure gas side closing valve 29.
On the other hand, the remaining refrigerant excluding the refrigerant sent from the liquid refrigerant communication pipe 9 to the connection unit 6 and the utilization unit 3 is sent to the receiver 25 through the liquid side closing valve 27 and the cooler 121 of the heat source unit 2. The refrigerant sent to the receiver 25 is temporarily stored in the receiver 25 and then decompressed by the heat source side expansion valve 24. The refrigerant depressurized by the heat source side expansion valve 24 is evaporated by exchanging heat with water as a heat source in the heat source side heat exchanger 23 to become a low pressure gas refrigerant, and is sent to the first switching mechanism 22. It is done. The low-pressure gas refrigerant sent to the first switching mechanism 22 is returned to the suction side of the compression mechanism 21 through the second port 22b and the third port 22c of the first switching mechanism 22. Thus, the operation in the cooling and heating simultaneous operation mode (evaporation load) is performed.

At this time, the heat source side heat exchanger 23 requires an evaporation load depending on the air conditioning load of each of the utilization units 3, 4, and 5, but the size may be very small. In such a case, similarly to the heating operation mode described above, the refrigerant evaporation capacity in the heat source side heat exchanger 23 of the heat source unit 2 is reduced to balance the air conditioning load of the entire usage units 3, 4, 5. There must be. In particular, in such a cooling and heating simultaneous operation mode, the cooling load of the usage unit 3 and the heating load of the usage units 4 and 5 may be approximately the same load. In such a case, the heat source side The evaporation load of the heat exchanger 23 must be very small.
However, in the air conditioner 1 of the present embodiment, a combination of refrigerating machine oil and refrigerant that does not separate into two layers in a temperature range of 30 ° C. or lower (more preferably, lower than the minimum value of the evaporation temperature) is used (that is, the heat source side). When the heat exchanger functions as an evaporator, a combination of refrigerating machine oil and refrigerant that do not separate into two layers is used in the heat source side heat exchanger, and the first oil return circuit 101 is provided. As described in the operation description of the operation mode, it is possible to prevent the refrigerating machine oil from being accumulated in the heat source side heat exchanger 23.

<Cooling and heating simultaneous operation mode (condensation load)>
Of the usage units 3, 4, 5, for example, the usage units 3, 4 are in a cooling operation and the usage unit 5 is in a heating / cooling simultaneous operation mode. Accordingly, the operation when the heat source side heat exchanger 23 of the heat source unit 2 is operated while functioning as a condenser (condensation operation state) will be described. At this time, the refrigerant circuit 12 of the air-conditioning apparatus 1 is configured as shown in FIG. 7 (see the arrows attached to the refrigerant circuit 12 in FIG. 7 for the refrigerant flow). Specifically, in the heat source side refrigerant circuit 12d of the heat source unit 2, the first switching mechanism 22 is switched to the condensing operation state (the state indicated by the solid line of the first switching mechanism 22 in FIG. 7), and the second switching mechanism. 26 is switched to the heating load request operation state (the state indicated by the broken line of the second switching mechanism 26 in FIG. 7), thereby causing the heat source side heat exchanger 23 to function as an evaporator and through the high-pressure gas refrigerant communication pipe 10. A high-pressure gas refrigerant compressed and discharged by the compression mechanism 21 can be supplied to the use unit 5. The heat source side expansion valve 24 is in an opened state. Note that the on-off valve 101b of the first oil return circuit 101 is closed, and the operation of extracting the refrigerating machine oil together with the refrigerant from the lower part of the heat source side heat exchanger 23 and returning it to the compression mechanism 21 is not performed. In the connection units 6 and 7, the use side heat exchangers 32 and 42 of the use units 3 and 4 function as an evaporator by closing the high pressure gas on / off valves 66 and 76 and opening the low pressure gas on / off valves 67 and 77. In addition, the use side heat exchangers 32 and 42 of the use units 3 and 4 and the suction side of the compression mechanism 21 of the heat source unit 2 are connected via the low-pressure gas refrigerant communication pipe 11. In the usage units 3 and 4, the usage-side expansion valves 31 and 41 include, for example, the degree of superheat of the usage-side heat exchangers 32 and 42 (specifically, the refrigerant temperature detected by the liquid-side temperature sensors 33 and 43). The opening degree is adjusted according to the cooling load of each utilization unit, such as the opening degree is adjusted based on the temperature difference between the refrigerant temperature detected by the gas side temperature sensors 34 and 44). In the connection unit 8, the use side heat exchanger 52 of the use unit 5 is caused to function as a condenser by closing the low pressure gas on / off valve 87 and opening the high pressure gas on / off valve 86. In the usage unit 5, the usage-side expansion valve 51 is, for example, the degree of supercooling of the usage-side heat exchanger 52 (specifically, the refrigerant temperature detected by the liquid side temperature sensor 53 and the gas side temperature sensor 54. The degree of opening is adjusted according to the heating load of the utilization unit, for example, the degree of opening is adjusted based on the temperature difference from the refrigerant temperature.

  In such a configuration of the refrigerant circuit 12, the high-pressure gas refrigerant compressed and discharged by the compressor 21a of the compression mechanism 21 is separated from most of the refrigerating machine oil accompanying the high-pressure gas refrigerant in the oil separator 21b. Then, it is sent to the first switching mechanism 22 and the second switching mechanism 26. The refrigerating machine oil separated in the oil separator 21b is returned to the suction side of the compressor 21a through the second oil return circuit 21d. Of the high-pressure gas refrigerant compressed and discharged by the compression mechanism 21, the high-pressure gas refrigerant sent to the first switching mechanism 22 passes through the first port 22 a and the second port 22 b of the first switching mechanism 22. It is sent to the side heat exchanger 23. The high-pressure gas refrigerant sent to the heat source side heat exchanger 23 is condensed by exchanging heat with water as a heat source in the heat source side heat exchanger 23. The refrigerant condensed in the heat source side heat exchanger 23 passes through the heat source side expansion valve 24, and then the high pressure gas refrigerant compressed and discharged by the compression mechanism 21 through the pressurizing circuit 111 is joined (for details). Sent to the receiver 25). The refrigerant sent to the receiver 25 is temporarily stored in the receiver 25 and then sent to the cooler 121. Then, the refrigerant sent to the cooler 121 is cooled by exchanging heat with the refrigerant flowing through the cooling circuit 122 (details will be described later). Then, the refrigerant cooled in the cooler 121 is sent to the liquid refrigerant communication pipe 9 through the liquid side closing valve 27.

On the other hand, among the high-pressure gas refrigerant compressed and discharged by the compression mechanism 21, the high-pressure gas refrigerant sent to the second switching mechanism 26 includes the first port 26a and the fourth port 26d of the second switching mechanism 26, and the high-pressure gas refrigerant. It is sent to the high-pressure gas refrigerant communication pipe 10 through the gas side closing valve 28.
Then, the high-pressure gas refrigerant sent to the high-pressure gas refrigerant communication pipe 10 is sent to the high-pressure gas connection pipe 83 of the connection unit 8. The high-pressure gas refrigerant sent to the high-pressure gas connection pipe 83 of the connection unit 8 is sent to the use-side heat exchanger 52 of the use unit 5 through the high-pressure gas on-off valve 86 and the merged gas connection pipe 85.
The high-pressure gas refrigerant sent to the use-side heat exchanger 52 is condensed by exchanging heat with indoor air in the use-side heat exchanger 52 of the use unit 5. On the other hand, indoor air is heated and supplied indoors. The refrigerant condensed in the use side heat exchanger 52 is sent to the liquid connection pipe 81 of the connection unit 8 after passing through the use side expansion valve 51.

Then, the refrigerant sent to the liquid connection pipe 81 is sent to the liquid refrigerant communication pipe 9, and the first switching mechanism 22, the heat source side heat exchanger 23, the heat source side expansion valve 24, the receiver 25, the cooler 121, and the liquid It merges with the refrigerant sent to the liquid refrigerant communication pipe 9 through the side closing valve 27.
The refrigerant flowing through the liquid refrigerant communication pipe 9 is branched into two and sent to the liquid connection pipes 61 and 71 of the connection units 6 and 7. The refrigerant sent to the liquid connection pipes 61 and 71 of the connection units 6 and 7 is sent to the use side expansion valves 31 and 41 of the use units 3 and 4.
The refrigerant sent to the use side expansion valves 31 and 41 is evaporated by performing heat exchange with indoor air in the use side heat exchangers 32 and 42 after being decompressed by the use side expansion valves 31 and 41. And low-pressure gas refrigerant. On the other hand, indoor air is cooled and supplied indoors. Then, the low-pressure gas refrigerant is sent to the merged gas connection pipes 65 and 75 of the connection units 6 and 7.

The low-pressure gas refrigerant sent to the merged gas connection pipes 65 and 75 is sent to and merged with the low-pressure gas refrigerant communication pipe 11 through the low-pressure gas on-off valves 67 and 77 and the low-pressure gas connection pipes 64 and 74.
Then, the low-pressure gas refrigerant sent to the low-pressure gas refrigerant communication pipe 11 is returned to the suction side of the compression mechanism 21 through the low-pressure gas side closing valve 29. Thus, the operation in the cooling and heating simultaneous operation mode (condensation load) is performed.
At this time, the heat source side heat exchanger 23 requires a condensing load depending on the air conditioning load of each of the utilization units 3, 4, and 5, but the size may be very small. In such a case, similarly to the cooling operation mode described above, the refrigerant condensing capacity in the heat source side heat exchanger 23 of the heat source unit 2 is reduced to balance the air conditioning load of the entire use units 3, 4, 5. There must be. In particular, in such a cooling and heating simultaneous operation mode, the cooling load of the usage units 3 and 4 and the heating load of the usage unit 5 may be approximately the same. In such a case, the heat source side The condensation load of the heat exchanger 23 must be very small.
However, in the air conditioner 1 of the present embodiment, high-pressure gas refrigerant is joined to the downstream side of the heat source side expansion valve 24 through the pressurization circuit 111 while performing control to reduce the opening degree of the heat source side expansion valve 24. Thus, control is performed to increase the pressure of the refrigerant on the downstream side of the heat source side expansion valve 24, and the refrigerant that is decompressed by the heat source side expansion valve 24 and sent to the use side refrigerant circuits 12 a and 12 b is cooled by the cooler 121. Therefore, the gas refrigerant can be condensed, and it is not necessary to send a gas-liquid two-phase flow refrigerant having a large gas fraction to the use-side refrigerant circuits 12a and 12b.

(3) Features of the air conditioner The air conditioner 1 of the present embodiment has the following features.
(A)
In the air conditioner 1 of the present embodiment, when functioning as an evaporator, a heat source side refrigerant circuit 12d having a heat source side heat exchanger 23 configured such that refrigerant flows in from the lower side and flows out from the upper side, The refrigerant circuit 12 includes a plurality of use-side refrigerant circuits 12a, 12b, and 12c connected to each other. The refrigerating machine oil and refrigerant used in the refrigerant circuit 12 are 30 ° C. or less (more preferably, evaporation) A combination of refrigerating machine oil and refrigerant that does not separate into two layers in the temperature range below the minimum temperature) is used. Here, the evaporation temperature of the refrigerant in the heat source side heat exchanger 23 is a temperature of 30 ° C. or less (and more than the minimum value of the evaporation temperature) when water, air, or brine is used as the heat source. That is, as the refrigerating machine oil and refrigerant used in this refrigerant circuit, a combination of refrigerating machine oil and refrigerant that does not separate into two layers in the heat source side heat exchanger when the heat source side heat exchanger functions as an evaporator is used. Yes. For this reason, in the air conditioner 1, the refrigerating machine oil does not accumulate in the state of floating on the refrigerant level in the heat source side heat exchanger 23, but accumulates in the heat source side heat exchanger 23 in a state of being mixed with the refrigerant. It will be. The refrigerating machine oil accumulated in the heat source side heat exchanger 23 is returned to the suction side of the compression mechanism 21 together with the refrigerant by the first oil return circuit 101 connected to the lower part of the heat source side heat exchanger 23. ing. For this reason, in order to prevent the refrigeration oil from accumulating in the heat source side heat exchanger as in the conventional air conditioner, the liquid level of the refrigerant in the heat source side heat exchanger is maintained at a certain level or more. There is no need to do it.

Thereby, in the air conditioning apparatus 1, the evaporation capability of the heat source side heat exchanger 23 is reduced by reducing the opening degree of the heat source side expansion valve 24 according to the air conditioning load of the plurality of use side refrigerant circuits 12a, 12b, 12c. As a result, even if the refrigerant level in the heat source side heat exchanger 23 is lowered, the refrigeration oil does not accumulate in the heat source side heat exchanger 23. Therefore, the heat source side heat exchanger It is possible to expand the control range when the evaporation capacity 23 is controlled by the heat source side expansion valve.
And in air conditioning apparatus 1, when providing a plurality of heat source side heat exchangers and making a heat source side heat exchanger function as an evaporator like the conventional air conditioning apparatus, it is a part of a plurality of heat source side expansion valves. By reducing the number of heat source side heat exchangers that function as evaporators and by reducing the number of heat source side heat exchangers, or by functioning a part of multiple heat source side heat exchangers as condensers Since it is not necessary to perform control to reduce the evaporation capacity by offsetting the evaporation capacity of the heat source side heat exchanger, a wide range of control of the evaporation capacity can be obtained by a single heat source side heat exchanger.
This makes it possible to unify the heat source side heat exchanger in an air conditioner where unification of the heat source side heat exchanger has not been realized due to the control width limitation of the evaporation capacity control of the heat source side heat exchanger. Therefore, the increase in the number of parts and cost increase caused by installing multiple heat source side heat exchangers in the conventional air conditioner can be prevented, and some of the multiple heat source side heat exchangers can be condensed. When the evaporation capacity is reduced by functioning as a heat exchanger, the amount of refrigerant compressed in the compression mechanism increases by the amount of refrigerant condensed in the heat source side heat exchanger, and the air conditioning load of the entire plurality of usage side refrigerant circuits is small It is possible to solve the problem that the COP in the operating condition is deteriorated.

(B)
In the air conditioner 1 of the present embodiment, the first oil return circuit 101 is provided with the on-off valve 101b, and when the heat source side heat exchanger 23 functions as a condenser, the on-off valve 101b is closed. Therefore, it is possible to prevent the amount of refrigerant sent to the use-side refrigerant circuits 12a, 12b, and 12c from being reduced after being condensed in the heat source side heat exchanger 23.
Further, in the air conditioner 1, it is not necessary to use the first oil return circuit 101 until the liquid level of the refrigerant in the heat source side heat exchanger 23 reaches a certain level or more at which the refrigerating machine oil does not accumulate. The opening degree of the heat source side expansion valve 24 corresponding to the refrigerant level at which the refrigerating machine oil can accumulate in the side heat exchanger 23 is set as a predetermined opening degree, and the opening degree of the heat source side expansion valve 24 is set to the predetermined opening degree. By opening and operating the on-off valve 101b only when the temperature becomes less than or equal to the degree, it is possible to prevent an increase in the amount of refrigerant sent to the compression mechanism 21 without being evaporated in the heat source side heat exchanger 23.

(C)
In the air conditioner 1 of the present embodiment, a plate heat exchanger is used as the heat source side heat exchanger 23. Due to its structure, a refrigerant is used to prevent refrigerating machine oil from accumulating in the heat source side heat exchanger 23. It is difficult to extract the refrigerating machine oil accumulated in a state of floating above the liquid level from the vicinity of the liquid level of the refrigerant. However, in the air conditioner 1 of the present embodiment, the refrigerating machine oil is accumulated in the heat source side heat exchanger 23 in a state where it is mixed with the refrigerant, and the refrigerating machine oil accumulated in the heat source side heat exchanger 23 is combined with the refrigerant in the heat source side heat. Since it is only necessary to extract from the lower part of the exchanger 23, the first oil return circuit 101 can be easily installed even when a plate heat exchanger is used.

(D)
In the air conditioner 1 of the present embodiment, when the refrigerant condensed in the heat source side heat exchanger 23 functioning as a condenser is decompressed by the heat source side expansion valve 24 and sent to the use side refrigerant circuits 12a, 12b, 12c. The high-pressure gas refrigerant joins and is pressurized from the pressurizing circuit 111, and the refrigerant pressure on the downstream side of the heat source side expansion valve 24 is increased. Here, the refrigerant sent to the use-side refrigerant circuits 12a, 12b, and 12c becomes a gas-liquid two-phase flow with a large gas fraction by simply joining the high-pressure gas refrigerant as in the conventional air conditioner, As a result, although the opening degree of the heat source side expansion valve 24 cannot be made sufficiently small, in the air conditioner 1, the pressure is reduced by the heat source side expansion valve 24 and sent to the use side refrigerant circuits 12a, 12b, 12c. Since the refrigerant is cooled by the cooler 121, the gas refrigerant can be condensed, and the gas-liquid two-phase flow refrigerant having a large gas fraction is not sent to the use-side refrigerant circuits 12a, 12b, and 12c. You can do it.
Thereby, in the air conditioning apparatus 1, the condensation capability of the heat source side heat exchanger 23 is reduced by reducing the opening degree of the heat source side expansion valve 24 according to the air conditioning load of the plurality of use side refrigerant circuits 12a, 12b, 12c. Even when the pressurization circuit 111 performs control to join and pressurize the high-pressure gas refrigerant, the gas-liquid two-phase flow refrigerant having a large gas fraction is sent to the use-side refrigerant circuits 12a, 12b, and 12c. This eliminates the need to expand the control range when the evaporation capability of the heat source side heat exchanger 23 is controlled by the heat source side expansion valve 24.
And in air conditioning apparatus 1, when providing a plurality of heat source side heat exchangers and making a heat source side heat exchanger function as a condenser like the conventional air conditioning apparatus, it is a part of a plurality of heat source side expansion valves. By reducing the number of heat source side heat exchangers that function as evaporators and by reducing the number of heat source side heat exchangers, or by functioning a part of multiple heat source side heat exchangers as condensers Since it is not necessary to control to reduce the evaporation capacity by offsetting the evaporation capacity of the heat source side heat exchanger, a wide range of control of the condensation capacity can be obtained by a single heat source side heat exchanger.
This makes it possible to unify the heat source side heat exchanger in an air conditioner where unification of the heat source side heat exchanger has not been realized due to the control width limitation of the control of the condensation capacity of the heat source side heat exchanger. Therefore, the increase in the number of parts and the cost increase caused by installing a plurality of heat source side heat exchangers in the conventional air conditioner can be prevented, and a part of the plurality of heat source side heat exchangers can be evaporated. When the condensation capacity is reduced by functioning as a condenser, the amount of refrigerant compressed in the compression mechanism is increased by the amount of refrigerant condensed in the heat source side heat exchanger, and the air conditioning load of the entire plurality of usage side refrigerant circuits is small It is possible to solve the problem that the COP in the operating condition is deteriorated.

(E)
In the air conditioning apparatus 1 of the present embodiment, the pressurization circuit 111 is connected so that the high-pressure gas refrigerant is merged between the heat source side expansion valve 24 and the cooler 121, and therefore the high-pressure gas refrigerant is merged. Thus, the refrigerant whose temperature has risen is cooled by the cooler 121. Thereby, it is not necessary to use a low temperature cold heat source as a cold heat source for cooling the refrigerant in the cooler 121, and a relatively high temperature cold heat source can be used.
Further, in the air conditioner 1, a part of the refrigerant sent from the downstream side of the heat source side expansion valve 24 to the use side refrigerant circuits 12a, 12b, 12c is reduced to a refrigerant pressure that can be returned to the suction side of the compression mechanism 21. Since a thing is used as the cooling source of the cooler 121, a cooling source having a temperature sufficiently lower than the temperature of the refrigerant sent from the downstream side of the heat source side expansion valve 24 to the use side refrigerant circuits 12a, 12b, 12c is obtained. be able to. As a result, the refrigerant sent from the downstream side of the heat source side expansion valve 24 to the use side refrigerant circuits 12a, 12b, 12c can be cooled to a supercooled state.

(F)
In the air conditioning apparatus 1 of the present embodiment, water that is supplied in a constant amount is used as a heat source regardless of the flow rate control of the refrigerant flowing in the heat source side heat exchanger 23, and the heat source side heat exchanger is controlled by controlling the amount of water. The evaporation capacity at 23 cannot be controlled. However, in the air conditioner 1, the control range when the evaporation capacity or the condensation capacity of the heat source side heat exchanger 23 is controlled by the heat source side expansion valve 24 is expanded, so even if the water amount is not controlled, It is possible to secure a control width when controlling the evaporation capability of the heat source side heat exchanger 23.

(4) Modification 1
In the air conditioner 1 described above, in order to configure an air conditioner capable of simultaneous cooling and heating, the heat source unit 2 and the utilization units 3, 4, 5 are connected to the refrigerant communication pipes 9, 10, 11 and the connection unit 6, As shown in FIG. 8, the heat source unit 2 and the utilization units 3, 4, and 5 are connected to the refrigerant in order to configure an air conditioner that can perform a cooling / heating switching operation. You may connect via the piping 9 and 10 only. Specifically, in the air conditioner 1 of the present modification, the low-pressure gas refrigerant communication pipe 11 and the connection units 6, 7, and 8 that are necessary for enabling simultaneous cooling and heating are omitted, and the use units 3, 4, 5 is directly connected to the liquid refrigerant communication pipe 9 and the high pressure gas refrigerant communication pipe 10, and the high pressure gas refrigerant communication pipe 10 is returned from the utilization units 3, 4, 5 to the heat source unit 2 by switching of the second switching mechanism 26. The high-pressure gas refrigerant communication pipe 10 can be made to function as a pipe through which the high-pressure gas refrigerant supplied from the heat source unit 2 to the utilization units 3, 4 and 5 flows.

Next, the operation (heating operation mode and cooling operation mode) of the air conditioner 1 of the present modification will be described.
First, the heating operation mode will be described. When all the utilization units 3, 4, and 5 are heated, the refrigerant circuit 12 of the air conditioner 1 is configured as shown in FIG. 9 (the refrigerant flow is attached to the refrigerant circuit 12 of FIG. (See the arrow that appears.) Specifically, in the heat source side refrigerant circuit 12d of the heat source unit 2, the first switching mechanism 22 is switched to the evaporation operation state (the state indicated by the broken line of the first switching mechanism 22 in FIG. 9), and the second switching mechanism. 26 is switched to the heating load required operation state (the state indicated by the broken line of the second switching mechanism 26 in FIG. 9), thereby causing the heat source side heat exchanger 23 to function as an evaporator and through the high-pressure gas refrigerant communication pipe 10. The high-pressure gas refrigerant compressed and discharged by the compression mechanism 21 can be supplied to the use units 3, 4, and 5. Moreover, the opening degree of the heat source side expansion valve 24 is adjusted so as to depressurize the refrigerant. The on-off valve 111b of the pressurizing circuit 111 and the cooling circuit side expansion valve 122b of the cooling circuit 122 are closed, and a high-pressure gas refrigerant is combined with the refrigerant flowing between the heat source side expansion valve 24 and the receiver 25. The supply of the cold heat source to the cooler 121 is shut off, and the refrigerant flowing between the receiver 25 and the utilization units 3, 4, 5 is not cooled. In the usage units 3, 4, and 5, the usage side expansion valves 31, 41, 51 are, for example, the degree of supercooling of the usage side heat exchangers 32, 42, 52 (specifically, the liquid side temperature sensors 33, 43). , 53 based on the refrigerant temperature detected by the gas side temperature sensors 34, 44, 54 and the refrigerant temperature detected by the gas side temperature sensors 34, 44, 54). Has been.

In such a configuration of the refrigerant circuit 12, the high-pressure gas refrigerant compressed and discharged by the compressor 21a of the compression mechanism 21 is separated from most of the refrigerating machine oil accompanying the high-pressure gas refrigerant in the oil separator 21b. Then, it is sent to the second switching mechanism 26. The refrigerating machine oil separated in the oil separator 21b is returned to the suction side of the compressor 21a through the second oil return circuit 21d. The high-pressure gas refrigerant sent to the second switching mechanism 26 is sent to the high-pressure gas refrigerant communication pipe 10 through the first port 26 a and the fourth port 26 d of the second switching mechanism 26 and the high-pressure gas side closing valve 28. .
The high-pressure gas refrigerant sent to the high-pressure gas refrigerant communication pipe 10 is branched into three and sent to the use side heat exchangers 32, 42, 52 of the use units 3, 4, 5.
The high-pressure gas refrigerant sent to the usage-side heat exchangers 32, 42, 52 exchanges heat with indoor air in the usage-side heat exchangers 32, 42, 52 of the usage units 3, 4, 5. Condensed by. On the other hand, indoor air is heated and supplied indoors. The refrigerant condensed in the use side heat exchangers 32, 42, 52 passes through the use side expansion valves 31, 41, 51 and then is sent to the liquid refrigerant communication pipe 9 to join.

Then, the refrigerant sent to the liquid refrigerant communication pipe 9 and merged is sent to the receiver 25 through the liquid side closing valve 27 and the cooler 121 of the heat source unit 2. The refrigerant sent to the receiver 25 is temporarily stored in the receiver 25 and then decompressed by the heat source side expansion valve 24. The refrigerant depressurized by the heat source side expansion valve 24 is evaporated by exchanging heat with water as a heat source in the heat source side heat exchanger 23 to become a low pressure gas refrigerant, and is sent to the first switching mechanism 22. It is done. The low-pressure gas refrigerant sent to the first switching mechanism 22 is returned to the suction side of the compression mechanism 21 through the second port 22b and the third port 22c of the first switching mechanism 22. In this way, the operation in the heating operation mode is performed.
Even in this case, the heating load of each of the usage units 3, 4, and 5 may be very small, but it is not separated into two layers in a temperature range of 30 ° C. or lower (more preferably, lower than the minimum value of the evaporation temperature). A combination of refrigeration oil and refrigerant (that is, a combination of refrigeration oil and refrigerant that does not separate into two layers in the heat source side heat exchanger when the heat source side heat exchanger functions as an evaporator); Since the 1 oil return circuit 101 is provided, it is possible to prevent the refrigerating machine oil from accumulating in the heat source side heat exchanger 23 as in the heating operation mode of the air conditioner configured to be capable of simultaneous cooling and heating. It can be done.

  Next, the cooling operation mode will be described. When all the use units 3, 4, and 5 are in cooling operation, the refrigerant circuit 12 of the air conditioner 1 is configured as shown in FIG. 10 (the refrigerant flow is attached to the refrigerant circuit 12 in FIG. 10). (See the arrow that appears.) Specifically, in the heat source side refrigerant circuit 12d of the heat source unit 2, the first switching mechanism 22 is switched to the condensation operation state (the state indicated by the solid line of the first switching mechanism 22 in FIG. 10), and the second switching mechanism. 26 is switched to the cooling operation state during cooling / heating switching (the state indicated by the solid line of the second switching mechanism 26 in FIG. 10), so that the heat source side heat exchanger 23 functions as a condenser and the high-pressure gas refrigerant communication pipe 10 The low-pressure gas refrigerant returned to the heat source unit 2 from the utilization units 3, 4, and 5 can be sent to the suction side of the compression mechanism 21. The heat source side expansion valve 24 is in an opened state. Note that the on-off valve 101b of the first oil return circuit 101 is closed, and the operation of extracting the refrigerating machine oil together with the refrigerant from the lower part of the heat source side heat exchanger 23 and returning it to the compression mechanism 21 is not performed. In the usage units 3, 4, and 5, the usage side expansion valves 31, 41, 51 are, for example, the degree of superheat (specifically, the liquid side temperature sensors 33, 43, The opening degree is adjusted according to the cooling load of each usage unit, for example, the opening degree is adjusted based on the temperature difference between the refrigerant temperature detected by 53 and the refrigerant temperature detected by the gas side temperature sensors 34, 44, 54). ing.

  In such a configuration of the refrigerant circuit 12, the high-pressure gas refrigerant compressed and discharged by the compressor 21a of the compression mechanism 21 is separated from most of the refrigerating machine oil accompanying the high-pressure gas refrigerant in the oil separator 21b. And sent to the first switching mechanism 22. The refrigerating machine oil separated in the oil separator 21b is returned to the suction side of the compressor 21a through the second oil return circuit 21d. The high-pressure gas refrigerant sent to the first switching mechanism 22 is sent to the heat source side heat exchanger 23 through the first port 22 a and the second port 22 b of the first switching mechanism 22. The high-pressure gas refrigerant sent to the heat source side heat exchanger 23 is condensed by exchanging heat with water as the heat source in the heat source side heat exchanger 23. The refrigerant condensed in the heat source side heat exchanger 23 passes through the heat source side expansion valve 24, and then the high pressure gas refrigerant compressed and discharged by the compression mechanism 21 through the pressurizing circuit 111 is joined to the receiver 25. Sent to. The refrigerant sent to the receiver 25 is temporarily stored in the receiver 25 and then sent to the cooler 121. Then, the refrigerant sent to the cooler 121 is cooled by exchanging heat with the refrigerant flowing through the cooling circuit 122. Then, the refrigerant cooled in the cooler 121 is sent to the liquid refrigerant communication pipe 9 through the liquid side closing valve 27.

Then, the refrigerant sent to the liquid refrigerant communication pipe 9 is branched into three and sent to the use side expansion valves 31, 41, 51 of the use units 3, 4, 5.
The refrigerant sent to the use side expansion valves 31, 41, 51 is decompressed by the use side expansion valves 31, 41, 51, and then exchanges heat with indoor air in the use side heat exchangers 32, 42, 52. Is evaporated to become a low-pressure gas refrigerant. On the other hand, indoor air is cooled and supplied indoors. Then, the low-pressure gas refrigerant is sent to the high-pressure gas refrigerant communication pipe 10 and merges.
The low-pressure gas refrigerant that has been sent to the high-pressure gas refrigerant communication pipe 10 and merged is sucked into the compression mechanism 21 through the high-pressure gas side closing valve 28 and the fourth port 26d and the third port 26c of the second switching mechanism 26. Back to the side. In this way, the operation in the cooling operation mode is performed.
Even in this case, the cooling load of each of the utilization units 3, 4, and 5 may be very small, but the downstream side of the heat source side expansion valve 24 is controlled while performing control to reduce the opening degree of the heat source side expansion valve 24. The high-pressure gas refrigerant is joined through the pressurizing circuit 111 to increase the pressure of the refrigerant on the downstream side of the heat source side expansion valve 24, and the use side refrigerant circuit 12a is decompressed by the heat source side expansion valve 24. The refrigerant sent to 12b, 12c is cooled by the cooler 121, so that the gas refrigerant is condensed in the same manner as in the cooling operation mode of the air conditioner configured to be capable of simultaneous cooling and heating. Therefore, it is not necessary to send a gas-liquid two-phase flow refrigerant having a large gas fraction to the use-side refrigerant circuits 12a, 12b, and 12c.

(5) Modification 2
In the air conditioning apparatus 1 described above, the control range of the control of the evaporation capacity of the heat source side heat exchanger 23 by the heat source side expansion valve 24 and the control of the control of the condensation capacity of the heat source side heat exchanger 23 by the heat source side expansion valve 24. In order to expand both the width and the first oil return circuit 101, the pressurizing circuit 111, the cooler 121, and the cooling circuit 122 are provided in the heat source unit 2, for example, the heat source side heat exchanger 23 When the control width of the control of the condensation capacity is secured, but it is necessary to expand only the control width of the control of the evaporation capacity of the heat source side heat exchanger 23, as shown in FIG. Only the oil return circuit 101 (that is, the pressurizing circuit 111, the cooler 121, and the cooling circuit 122 are omitted) may be provided in the heat source unit 2 (that is, the pressurizing circuit 111, the cooler 121, and the cooling circuit 122 are provided). Omitted It may be).

(6) Modification 3
In the air conditioning apparatus 1 described above, four-way switching valves are used as the first switching mechanism 22 and the second switching mechanism 26, but the present invention is not limited to this. For example, as shown in FIG. A three-way valve may be used as the switching mechanism 22 and the second switching mechanism 26.

(7) Modification 4
In the air conditioner 1 described above, the flow rates of the refrigerating machine oil and the refrigerant returned from the lower part of the heat source side heat exchanger 23 functioning as an evaporator through the first oil return circuit 101 to the compression mechanism 21 are the first oil return circuit 101. Is determined in accordance with the pressure loss between the lower part of the heat source side heat exchanger 23 that functions as an evaporator and the compression mechanism 21, for example, in the heat source side heat exchanger 23 that functions as an evaporator or heat source side heat. In the case where the pressure loss in the pipe from the refrigerant outlet side of the exchanger 23 to the suction side of the compression mechanism 21 is small and the pressure loss in the first oil return circuit 101 becomes small, the heat source side heat exchanger 23 The refrigerating machine oil and the refrigerant having a flow rate sufficient to prevent the refrigerating machine oil from being accumulated in the compression mechanism 2 from the lower part of the heat source side heat exchanger 23 through the first oil return circuit 101. You may not be able to return to may occur.
Even in such a case, the refrigerating machine oil and the refrigerant having a flow rate sufficient to prevent the refrigerating machine oil from being accumulated in the heat source side heat exchanger 23 are supplied to the heat source side heat exchanger 23 through the first oil return circuit 101. As shown in FIG. 13, between the refrigerant outlet side of the heat source side heat exchanger 23 functioning as an evaporator and the suction side of the compression mechanism 21. The gas refrigerant that is evaporated in the heat source side heat exchanger 23 and returned to the suction side of the compression mechanism 21 is returned to the compression mechanism 21 from the lower part of the heat source side heat exchanger 23 through the first oil return circuit 101. You may make it further provide the pressure reduction mechanism 131 which can be pressure-reduced before joining with the refrigeration oil and refrigerant | coolant which are made.
The pressure reducing mechanism 131 is mainly composed of an on-off valve 131a composed of an electromagnetic valve connected to a pipe connecting the third port 22c of the first switching mechanism 22 and the suction side of the compression mechanism 21, and a bypass pipe bypassing the on-off valve 131a. 131b. A capillary tube 131c is connected to the bypass tube 131b. In the decompression mechanism 131, when the first oil return circuit 101 is used, the on-off valve 131a is closed so that the gas refrigerant evaporated in the heat source side heat exchanger 23 flows only through the bypass pipe 131b. In this case, the first oil return circuit 101 is used because the on-off valve 131a can be opened and both the on-off valve 131a and the bypass pipe 131b can be operated so that the gas refrigerant evaporated in the heat source side heat exchanger 23 flows. In this case, the pressure loss between the refrigerant outlet side of the heat source side heat exchanger 23 functioning as an evaporator and the suction side of the compression mechanism 21 is increased (that is, the decompression mechanism 131 is connected to the first oil return circuit). A differential pressure increasing mechanism for increasing a differential pressure between the lower part of the heat source side heat exchanger 23 and the refrigerating machine oil and refrigerant returned to the compression mechanism 21 through 101. Be made to function Te in), it is possible to increase the flow rate of refrigerating machine oil and refrigerant returned to the compression mechanism 21 from the lower portion of the heat source-side heat exchanger 23 through the first oil returning circuit 101. Thereby, the refrigerating machine oil and the refrigerant having a flow rate sufficient to prevent the refrigerating machine oil from being accumulated in the heat source side heat exchanger 23 are reliably supplied to the heat source side heat exchanger 23 through the first oil return circuit 101. It can return to the compression mechanism 21 from the lower part. If the pressure loss in the bypass pipe 131b can be set appropriately without connecting the capillary tube 131c, the capillary tube 131c is unnecessary.

  Further, the pressure reducing mechanism as the differential pressure increasing mechanism is not the on-off valve 131a and the bypass pipe 131b like the pressure reducing mechanism 131 described above, but is compressed with the third port 22c of the first switching mechanism 22 as shown in FIG. An electric expansion valve connected to a pipe connecting the suction side of the mechanism 21 may be used. In the decompression mechanism 141, when the first oil return circuit 101 is used, the suction side of the compression mechanism 21 is controlled from the refrigerant outlet side of the heat source side heat exchanger 23 that functions as an evaporator by performing control to reduce the opening degree. The pressure loss during the period up to 1 can be increased so that the flow rates of the refrigerating machine oil and the refrigerant returned from the lower part of the heat source side heat exchanger 23 to the compression mechanism 21 through the first oil return circuit 101 can be increased. In this case, since the opening degree can be controlled to be large (for example, fully open), the refrigerating machine oil having a flow rate sufficient to prevent the refrigerating machine oil from being accumulated in the heat source side heat exchanger 23 and The refrigerant can be reliably returned to the compression mechanism 21 from the lower part of the heat source side heat exchanger 23 through the first oil return circuit 101.

  Further, the first oil return circuit 101 may be provided with a pump mechanism 151 as a differential pressure increasing mechanism as shown in FIG. 15 without using the pressure reducing mechanism 131 and the pressure reducing mechanism 141 as described above. For example, the pump mechanism 151 can use a refrigerant pump. The pump mechanism 151 pressurizes the refrigeration oil accumulated in the heat source side heat exchanger 23 and sends it to the first oil return circuit 101 (that is, the pump mechanism 151 exchanges heat source side heat through the first oil return circuit 101). The heat source side heat exchanger through the first oil return circuit 101) by functioning as a differential pressure increasing mechanism that increases the differential pressure between the lower part of the cooler 23 and the refrigeration oil and refrigerant returned to the compression mechanism 21. The flow rates of the refrigerating machine oil and the refrigerant returned to the compression mechanism 21 from the lower part of the 23 can be increased. Thereby, the refrigerating machine oil and the refrigerant having a flow rate sufficient to prevent the refrigerating machine oil from being accumulated in the heat source side heat exchanger 23 are reliably supplied to the heat source side heat exchanger 23 through the first oil return circuit 101. It can return to the compression mechanism 21 from the lower part.

  Further, instead of the pump 151, as shown in FIG. 16, an ejector mechanism 161 as a differential pressure increasing mechanism may be provided. The ejector mechanism 161 mainly includes an ejector 161a provided in the first oil return circuit 101, and a high-pressure gas refrigerant serving as a driving fluid for the ejector 161a on the discharge side of the compression mechanism 21 (in this modification, an oil separator 21b It consists of a branch pipe 161b that branches from the first port 22a of the first switching mechanism 22 and an on-off valve 161c provided in the branch pipe 161b. In the ejector mechanism 161, when the first oil return circuit 101 is used, the on-off valve 161a is opened to supply a high-pressure gas refrigerant as a driving fluid from the discharge side of the compression mechanism 21 to the ejector 161a. By sucking the refrigeration oil accumulated in the lower part of the heat source side heat exchanger 23 and sending it to the first oil return circuit 101 (that is, the ejector mechanism 161 is passed through the first oil return circuit 101 to the heat source side heat exchanger 23. Of the heat source side heat exchanger 23 through the first oil return circuit 101) by functioning as a differential pressure increasing mechanism that increases the differential pressure until the refrigerant oil and the refrigerant returned to the compression mechanism 21 are joined from the lower part of the compressor. The flow rates of the refrigerating machine oil and the refrigerant returned to the compression mechanism 21 from the lower part can be increased. Thereby, the refrigerating machine oil and the refrigerant having a flow rate sufficient to prevent the refrigerating machine oil from being accumulated in the heat source side heat exchanger 23 are reliably supplied to the heat source side heat exchanger 23 through the first oil return circuit 101. It can return to the compression mechanism 21 from the lower part.

(8) Other Embodiments Although the embodiments of the present invention have been described with reference to the drawings, the specific configuration is not limited to these embodiments and can be changed without departing from the gist of the invention. It is.

  According to the present invention, in an refrigeration apparatus and an air conditioner having a refrigerant circuit having an evaporator configured to allow refrigerant to flow in from the lower side and flow out from the upper side, the evaporation capacity of the evaporator is increased by an expansion valve. The control range at the time of control can be expanded.

Claims (14)

The compression mechanism (21), the condenser (32, 42, 52), the expansion valve (24), and the evaporator (23) configured to allow the refrigerant to flow from the lower side and flow from the upper side are connected. A refrigerant circuit (12) in which a combination of refrigeration oil and refrigerant not separated into two layers in a temperature range of 30 ° C. or lower is used,
An oil return circuit (101) connected to the lower part of the evaporator and returning the refrigeration oil accumulated in the evaporator together with the refrigerant to the compression mechanism;
A refrigeration apparatus (1).   The refrigerating machine (1) according to claim 1, wherein the refrigerating machine oil and refrigerant used in the refrigerant circuit (12) are a combination of refrigerating machine oil and refrigerant that do not separate into two layers in a temperature range of -5 ° C or lower.   The refrigerating apparatus (1) according to claim 2, wherein the combination of refrigerating machine oil and refrigerant used in the refrigerant circuit (12) is ether oil and R410A.   A differential pressure increasing mechanism for increasing a differential pressure between the lower part of the heat source side heat exchanger (23) through the oil return circuit (101) and the refrigeration oil and refrigerant returned to the compression mechanism (21). 131, 141, 151, 161) The refrigeration apparatus (1) according to any one of claims 1 to 3, further comprising: A compression mechanism (21), a condenser (32, 42, 52), an expansion valve (24), and an evaporator (23) configured to allow refrigerant to flow in from the lower side and flow out from the upper side are connected. A refrigerant circuit (12) in which a combination of refrigerating machine oil and refrigerant not separated into two layers is used in the evaporator, and
An oil return circuit (101) connected to the lower part of the evaporator and returning the refrigeration oil accumulated in the evaporator together with the refrigerant to the compression mechanism;
A refrigeration apparatus (1). A compression mechanism (21) and a heat source side heat exchanger (23) and a heat source side expansion valve (24) configured such that when functioning as an evaporator, refrigerant flows in from the lower side and flows out from the upper side A plurality of use side heat exchangers (32, 42, 52) and use side expansion valves (31, 41, 51) connected to the heat source side refrigerant circuit (12d) configured to be connected. A refrigerant circuit (12) in which a combination of refrigerating machine oil and refrigerant that are not separated into two layers in a temperature range of 30 ° C. or lower is used, wherein the refrigerant circuit (12a, 12b, 12c) is used.
An oil return circuit (101) connected to the lower part of the heat source side heat exchanger and returning the refrigeration oil accumulated in the heat source side heat exchanger to the compression mechanism together with a refrigerant;
An air conditioner (1) comprising:   The air conditioner (1) according to claim 6, wherein the refrigerating machine oil and refrigerant used in the refrigerant circuit (12) are a combination of refrigerating machine oil and refrigerant that do not separate into two layers in a temperature range of -5 ° C or lower. .   The air conditioner (1) according to claim 7, wherein the combination of refrigerating machine oil and refrigerant used in the refrigerant circuit (12) is ether oil and R410A.   A differential pressure increasing mechanism for increasing a differential pressure between the lower part of the heat source side heat exchanger (23) through the oil return circuit (101) and the refrigeration oil and refrigerant returned to the compression mechanism (21). 131, 141, 151, 161) The air conditioner (1) according to any one of claims 6 to 8, further comprising: The oil return circuit (101) has an on-off valve (101b),
The on-off valve is closed when the heat source side heat exchanger (23) functions as a condenser, and is opened when the heat source side heat exchanger functions as an evaporator.
The air conditioning apparatus (1) according to any one of claims 6 to 9.   The air conditioner (1) according to claim 10, wherein the on-off valve (101b) is opened when an opening degree of the heat source side expansion valve (24) becomes a predetermined opening degree or less.   12. The heat source side heat exchanger (23) uses water supplied as a heat source as a heat source regardless of the flow rate of the refrigerant flowing through the heat source side heat exchanger. The air conditioning apparatus (1) described.   The air conditioner (1) according to any one of claims 6 to 12, wherein the heat source side heat exchanger (23) is a plate heat exchanger. A compression mechanism (21), and a heat source side heat exchanger (23) and a heat source side expansion valve (24) configured such that, when functioning as an evaporator, refrigerant flows in from the lower side and flows out from the upper side, A plurality of use side heat exchangers (32, 42, 52) and use side expansion valves (31, 41, 51) connected to the heat source side refrigerant circuit (12d) connected and configured. The use side refrigerant circuit (12a, 12b, 12c) is connected, and when the heat source side heat exchanger functions as an evaporator, the heat source side heat exchanger does not separate into two layers. A refrigerant circuit (12) in which refrigeration oil and refrigerant are used;
An oil return circuit (101) connected to the lower part of the heat source side heat exchanger and returning the refrigeration oil accumulated in the heat source side heat exchanger to the compression mechanism together with a refrigerant;
An air conditioner (1) comprising:

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