WO2015182484A1 - Freezer device - Google Patents

Abstract

In the present invention a receiver (28) is provided with a receiver gas venting pipe (41) connecting the upper part of the receiver (28) and the suction side of a compressor (21), and the receiver gas venting pipe (41) is provided with a gas-venting-side flow volume adjustment valve (42) the degree of opening of which can be adjusted. The degree of opening of the gas-venting-side flow volume adjustment valve (42) is controlled so as to satisfy a supercooling degree control normal condition wherein a supercooling degree control can be performed by usage-side flow volume adjustment valves (51a, 51b, 51c, 51d) which are performing the supercooling degree control.

Description

Refrigeration equipment

The present invention relates to a refrigeration apparatus, in particular, a heat source unit having a receiver, and a utilization unit having a utilization side flow control valve and a utilization side heat exchanger are connected via a refrigerant communication pipe, and utilization side heat exchange. The present invention relates to a refrigeration apparatus that controls the opening degree of a usage-side flow rate adjustment valve based on the degree of refrigerant supercooling at the outlet of a usage-side heat exchanger in an operation that causes the cooler to function as a refrigerant radiator.

Conventionally, as shown in Patent Document 1 (Japanese Patent Laid-Open No. 2006-78026), an outdoor unit (heat source unit) having a receiver, an indoor electronic expansion valve (use side flow control valve), an outdoor heat exchanger (use side) Air that can be operated simultaneously with cooling and heating, which is a type of refrigeration system in which an indoor unit (utilization unit) having a heat exchanger is connected via a gas pipe and a liquid pipe (gas refrigerant communication pipe and liquid refrigerant communication pipe) There is a harmony machine.

In the conventional refrigeration system, when the indoor unit (use unit) performs a heating operation (when the use side heat exchanger functions as a refrigerant radiator), a desired heating capacity is secured in the use unit. In order to do so, supercooling degree control is performed to control the opening degree of the use side flow rate control valve based on the supercooling degree of the refrigerant at the outlet of the use side heat exchanger.

However, because the length of the liquid refrigerant communication pipe differs depending on the installation conditions and construction status of the refrigeration system, the pressure loss (liquid pressure loss) of the liquid refrigerant flowing through the liquid refrigerant communication pipe increases when the usage unit performs heating operation. There is. For this reason, the liquid refrigerant sent from the utilization unit to the heat source unit via the liquid refrigerant communication pipe is reduced in pressure according to the liquid pressure loss and accumulated in the receiver in a liquid saturated state, and the utilization side heat exchange The degree of supercooling of the refrigerant at the outlet of the vessel may increase depending on this hydraulic pressure loss. If the degree of supercooling of the refrigerant at the outlet of the use side heat exchanger exceeds the variable width of the use side flow rate control valve and becomes too large to control the degree of supercooling, the heat release of the use side heat exchanger There is a possibility that the capacity is lowered and the heating capacity in the utilization unit is lowered.

An object of the present invention is that a heat source unit having a receiver, a utilization unit having a utilization side flow rate adjustment valve and a utilization side heat exchanger are connected via a refrigerant communication pipe, and the utilization side heat exchanger is a refrigerant. In the operation to function as a radiator of the refrigerant, in the refrigeration apparatus that controls the opening degree of the use side flow rate control valve based on the degree of supercooling of the refrigerant at the outlet of the use side heat exchanger, even when the hydraulic pressure loss is large, The purpose is to appropriately control the degree of supercooling and to suppress a decrease in heating capacity.

In a refrigeration apparatus according to a first aspect, a heat source unit having a compressor, a heat source side heat exchanger, and a receiver, and a utilization unit having a utilization side flow rate adjustment valve and a utilization side heat exchanger are provided as a gas refrigerant communication pipe. And a liquid refrigerant communication pipe. In this refrigeration apparatus, in the operation in which the use side heat exchanger functions as a refrigerant radiator, the opening degree of the use side flow control valve is controlled based on the degree of subcooling of the refrigerant at the outlet of the use side heat exchanger. Control the degree of supercooling. Here, the receiver is provided with a receiver gas vent pipe that connects the upper part of the receiver and the suction side of the compressor, and the receiver gas vent pipe is provided with a gas vent-side flow rate adjustment valve capable of adjusting the opening. The opening degree of the degassing flow rate control valve is controlled so that the use side flow rate control valve performing the cooling degree control satisfies the normal condition of the supercooling degree control capable of performing the supercooling degree control. .

If the normal condition of the supercooling degree control is not satisfied due to the liquid pressure loss, the supercooling degree of the refrigerant at the outlet of the use side heat exchanger becomes larger than the desired supercooling degree such as the target supercooling degree, and the use side flow control valve Only by controlling the opening degree, the degree of supercooling of the refrigerant at the outlet of the use side heat exchanger cannot be reduced to a desired degree of supercooling such as the target degree of supercooling.

In order to eliminate such a situation, it is necessary to reduce the degree of refrigerant supercooling at the outlet of the use side heat exchanger by changing the state of the refrigerant accumulated in the receiver to a gas-liquid two-phase state.

Therefore, here, as described above, the receiver gas vent pipe is provided with a gas vent side flow rate control valve capable of adjusting the opening, and the gas vent side flow rate control valve is opened so as to satisfy the normal condition of the supercooling degree control. I try to control the degree. That is, by increasing the degree of opening of the degassing flow rate control valve, the refrigerant flowing into the receiver is brought into a gas-liquid two-phase state with a large amount of gas refrigerant, and the degree of refrigerant subcooling at the outlet of the use side heat exchanger To prevent the supercooling degree of the refrigerant at the outlet of the use side heat exchanger from exceeding the variable width of the use side flow rate control valve so that the supercooling degree control cannot be performed. The control normal condition is satisfied.

Thereby, here, even when the hydraulic pressure loss is large, the supercooling degree control can be appropriately performed, and the decrease in the heating capacity can be suppressed.

The refrigeration apparatus according to the second aspect is the refrigeration apparatus according to the first aspect, wherein the normal condition of the supercooling degree control is that the opening degree of the use side flow rate control valve performing the supercooling degree control is the upper limit of the supercooling degree control. It is less than the opening.

Here, as described above, whether or not the normal condition of the supercooling degree control is satisfied is determined based on whether or not the opening degree of the use side flow control valve is less than the supercooling degree control upper limit opening degree. That is, when the opening of the usage-side flow control valve is open to the supercooling degree control upper limit opening that is the upper limit opening in the supercooling degree control, the variable width of the usage side flow control valve is exceeded. Therefore, it is assumed that the degree of supercooling of the refrigerant at the outlet of the use side heat exchanger is so large that the supercooling degree control cannot be performed.

As a result, the opening degree of the use side flow rate control valve performing the supercooling degree control can be maintained below the supercooling degree control upper limit opening degree within the range of the variable width of the use side flow rate control valve. Supercooling degree control can be performed.

In the refrigeration apparatus according to the third aspect, in the refrigeration apparatus according to the first or second aspect, the gas flow control valve performing the supercooling degree control satisfies the normal condition of the supercooling degree control. If the usage-side flow control valve that controls the degree of subcooling does not satisfy the normal conditions for supercooling control, the control is performed to reduce the opening of the vent flow control valve. Control to increase the degree.

Here, as described above, the degassing side flow rate control valve is controlled to open and close depending on whether or not the normal supercooling degree control condition is satisfied. For this reason, the opening degree of the degassing side flow rate control valve can be maintained at the minimum opening degree necessary for satisfying the normal condition of the supercooling degree control.

This makes it possible to minimize the amount of gas refrigerant extracted from the receiver, and to suppress performance degradation due to outgassing from the receiver.

The refrigeration apparatus according to the fourth aspect is the refrigeration apparatus according to the third aspect, wherein when the receiver reaches a predetermined liquid level, the degassing side flow rate regardless of whether or not the normal condition of supercooling degree control is satisfied. Control to reduce the opening of the control valve.

When the gas refrigerant is extracted from the receiver by opening the gas vent side flow control valve, the liquid level of the liquid refrigerant collected in the receiver may rise and rise to near full liquid.

Therefore, here, as described above, when the receiver reaches a predetermined liquid level, it is a case where the normal condition for the supercooling degree control is not satisfied regardless of whether the normal condition for the supercooling degree control is satisfied. Even so, control is performed to forcibly reduce the opening degree of the gas vent side flow control valve.

Thereby, here, it is possible to prevent the liquid refrigerant from returning from the receiver to the compressor while appropriately performing the supercooling degree control.

1 is a schematic configuration diagram of a cooling and heating simultaneous operation type air conditioning apparatus as an embodiment of a refrigeration apparatus according to the present invention. It is the schematic which shows the structure of a receiver and its periphery. It is a figure which shows the operation | movement (flow of a refrigerant | coolant) in a cooling operation. It is a figure which shows the operation | movement (flow of a refrigerant | coolant) in heating operation. It is a figure which shows the operation | movement (flow of a refrigerant | coolant) in the heating / cooling simultaneous operation (evaporation load main body). It is a figure which shows the operation | movement (flow of a refrigerant | coolant) in the heating / cooling simultaneous operation (heat dissipation load main body). It is the Mollier diagram which showed the refrigerating cycle at the time of performing heating operation in the fully-closed state of the degassing side flow control valve. It is the Mollier diagram which showed the refrigerating cycle at the time of performing heating operation in the open state of the degassing side flow control valve. It is a flowchart of the opening degree control of a degassing side flow control valve.

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

(1) Configuration of Refrigeration Device (Cooling and Heating Simultaneous Operation Type Air Conditioner) FIG. 1 is a schematic configuration diagram of a cooling and heating simultaneous operation type air conditioning device 1 as an embodiment of the refrigeration device according to the present invention. The cooling and heating simultaneous operation type air conditioner 1 is an apparatus used for air conditioning in a room such as a building by performing a vapor compression refrigeration cycle operation.

The cooling and heating simultaneous operation type air conditioner 1 mainly includes one heat source unit 2, a plurality of (here, four) use units 3 a, 3 b, 3 c, 3 d, and each use unit 3 a, 3 b, 3 c, 3 d. Connecting units 4a, 4b, 4c, and 4d connected to each other, and refrigerant communication tubes 7 and 8 that connect the heat source unit 2 and the utilization units 3a, 3b, 3c, and 3d via the connection units 4a, 4b, 4c, and 4d. , 9. That is, the vapor compression refrigerant circuit 10 of the cooling and heating simultaneous operation type air conditioner 1 includes a heat source unit 2, utilization units 3a, 3b, 3c, and 3d, connection units 4a, 4b, 4c, and 4d, and a refrigerant communication tube. 7, 8 and 9 are connected to each other. In the cooling / heating simultaneous operation type air conditioner 1, each of the use units 3a, 3b, 3c, and 3d can individually perform the cooling operation or the heating operation, and the cooling operation is performed from the use unit that performs the heating operation. Heat is recovered between the utilization units by sending the refrigerant to the utilization unit to be performed (here, simultaneous cooling / heating operation in which the cooling operation and the heating operation are performed simultaneously) is possible. In addition, in the cooling and heating simultaneous operation type air conditioner 1, the heat load of the heat source unit 2 is changed according to the heat loads of the plurality of utilization units 3a, 3b, 3c, and 3d in consideration of the heat recovery (simultaneous cooling and heating operation). It is configured to balance.

<Usage unit>
The use units 3a, 3b, 3c, and 3d are installed by being embedded or suspended in a ceiling of a room such as a building, or by hanging on a wall surface of the room. The utilization units 3a, 3b, 3c, and 3d are connected to the heat source unit 2 via the refrigerant communication tubes 7, 8, and 9 and the connection units 4a, 4b, 4c, and 4d, and constitute a part of the refrigerant circuit 10. ing.

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

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

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

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

In addition, the use unit 3a is provided with various sensors. Specifically, a liquid side temperature sensor 82a that detects the temperature of the refrigerant on the liquid side of the use side heat exchanger 52a (an outlet when the use side heat exchanger 52a functions as a refrigerant radiator) is provided. . In addition, the usage unit 3a includes a usage-side control unit 50a that controls the operations of the units 51a and 54a constituting the usage unit 3a. The use-side control unit 50a includes a microcomputer and a memory provided for controlling the use unit 3a, and exchanges control signals and the like with a remote controller (not shown). Control signals and the like can be exchanged with the heat source unit 2.

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

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

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

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

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

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

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

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

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

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

The receiver 28 is a container for temporarily storing the refrigerant flowing between the heat source side heat exchangers 24 and 25 and the use side refrigerant circuits 13a, 13b, 13c, and 13d. A receiver inlet pipe 28 a is provided in the upper part of the receiver 28, and a receiver outlet pipe 28 b is provided in the lower part of the receiver 28. The receiver inlet pipe 28a is provided with a receiver inlet on / off valve 28c capable of opening / closing control. The inlet pipe 28 a and the outlet pipe 28 b of the receiver 28 are connected between the heat source side heat exchangers 24 and 25 and the liquid side shut-off valve 31 via the bridge circuit 29.

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

As shown in FIG. 2, the receiver 28 has a receiver liquid for detecting whether or not the liquid level in the receiver 28 has reached a predetermined position L1 below the position where the receiver degassing pipe 41 is connected. A surface detection tube 43 is connected. Here, the receiver liquid level detection tube 43 is provided so as to extract the refrigerant from a portion near the middle in the vertical direction of the receiver 28. And the receiver liquid level detection pipe | tube 43 has joined the receiver degassing pipe | tube 41 via the capillary tube 43a. Here, the receiver liquid level detection pipe 43 is provided so as to merge with a portion on the upstream side of the position where the gas vent side flow rate adjustment valve 42 of the receiver gas vent pipe 41 is provided. Further, the receiver gas vent pipe 41 is provided with a refrigerant heater 44 that heats the refrigerant flowing through the receiver gas vent pipe 41 on the downstream side of the position where the receiver liquid level detection pipe 43 joins. Here, the refrigerant heater 44 is a heat exchanger that heats the refrigerant flowing through the receiver degassing pipe 41 using the high-pressure gas refrigerant discharged from the compressor 21 as a heating source. Here, the refrigerant heater 44 divides a part of the high-pressure gas refrigerant discharged from the compressor 21 and sends it to the pre-cooling heat exchanger 35 that is a part of the heat source side heat exchangers 24, 25, 35. It consists of a pipe heat exchanger, a double pipe heat exchanger, etc. comprised by making a pipe | tube and the receiver degassing pipe | tube 41 contact. That is, the refrigerant heater 44 is connected to the upstream side of the precooling heat exchanger 35 through which the high-pressure gas refrigerant discharged from the compressor 21 always flows. During the refrigeration cycle operation, a part of the high-pressure gas refrigerant discharged from the compressor 21 is branched, and the refrigerant heater 44, the precooling heat exchanger 35, the refrigerant cooler 36, and the refrigerant cooling side flow rate adjustment valve 37. Through this, a flow that merges with the receiver outlet pipe 28b is obtained, and the refrigerant extracted from the receiver gas vent pipe 41 is heated by a part of the high-pressure gas refrigerant discharged from the compressor 21. .

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

Further, the bridge circuit 29 is provided with a supercooling heat exchanger 45 as a liquid pipe heat exchanger that performs heat exchange with the refrigerant flowing on the liquid side of the heat source side heat exchangers 24 and 25, and the heat source side heat exchanger A suction return pipe 46 is connected to return a part of the refrigerant flowing between the liquid side of 24, 25 and the liquid side of the use side heat exchangers 52 a, 52 b, 52 c, 52 d to the suction side of the compressor 21. The supercooling heat exchanger 45 is provided in the receiver outlet pipe 28b, and the refrigerant flowing through the receiver outlet pipe 28b using the refrigerant flowing through the suction return pipe 46 as a cooling source (that is, the liquid side of the heat source side heat exchangers 24 and 25). And a refrigerant flowing between the liquid side of the use side heat exchangers 52a, 52b, 52c, and 52d). Here, the supercooling heat exchanger 45 includes a pipe heat exchanger, a double pipe heat exchanger, and the like configured by bringing the suction return pipe 46 and the receiver outlet pipe 28b into contact with each other. The suction return pipe 46 is provided so as to be branched from the receiver outlet pipe 28 b, and connects the receiver outlet pipe 28 b and the suction side of the compressor 21 via the supercooling heat exchanger 45. The suction return pipe 46 is provided with a suction return side flow rate adjustment valve 47 for adjusting the flow rate of the refrigerant branched from the receiver outlet pipe 28b. The suction return side flow rate adjustment valve 47 is provided on the upstream side of the supercooling heat exchanger 45 of the suction return pipe 46. Here, the suction return side flow rate adjustment valve 47 is an electric expansion valve capable of adjusting the opening degree.

The high / low pressure switching mechanism 30, when sending the high-pressure gas refrigerant discharged from the compressor 21 to the use- side refrigerant circuits 13 a, 13 b, 13 c, and 13 d (hereinafter referred to as “heat dissipation load operation state”), 21 is connected to the high-low pressure gas side shut-off valve 32 (see the broken line of the high-low pressure switching mechanism 30 in FIG. 1), and the high-pressure gas refrigerant discharged from the compressor 21 is used on the use- side refrigerant circuits 13a, 13b. , 13c, 13d (hereinafter referred to as “evaporative load operation state”), the high / low pressure gas side shut-off valve 32 and the suction side of the compressor 21 are connected (high / low pressure switching in FIG. 1). (Refer to the solid line of the mechanism 30), which is a device capable of switching the refrigerant flow path in the heat source side refrigerant circuit 12, and includes, for example, a four-way switching valve.

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

The heat source unit 2 is provided with various sensors. Specifically, the suction pressure sensor 71 detects the refrigerant pressure on the suction side of the compressor 21, the discharge pressure sensor 73 detects the refrigerant pressure on the discharge side of the compressor 21, and the receiver degassing pipe 41. A degassing side temperature sensor 75 for detecting the temperature of the refrigerant and a suction return side temperature sensor 81 for detecting the temperature of the refrigerant flowing through the suction return pipe 46 are provided. Here, the degassing temperature sensor 75 is provided in the receiver degassing pipe 41 so as to detect the temperature of the refrigerant at the outlet of the refrigerant heater 44, and the suction return side temperature sensor 81 is provided in the supercooling heat exchanger 45. A suction return pipe 46 is provided to detect the temperature of the refrigerant at the outlet. Further, the heat source unit 2 includes a heat source side control unit 20 that controls operations of the respective units 21 a, 22, 23, 26, 27, 28 c, 30, 34 a, 37, 42, and 47 constituting the heat source unit 2. . The heat source side control unit 20 includes a microcomputer and a memory provided to control the heat source unit 2, and uses side control units 50a, 50b, 50c of the usage units 3a, 3b, 3c, 3d. , 50d can exchange control signals and the like.

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

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

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

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

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

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

Further, the connection unit 4a has a connection side control unit 60a for controlling the operation of each unit 66a, 67a constituting the connection unit 4a. The connection-side control unit 60a includes a microcomputer and a memory provided for controlling the connection unit 60a, and exchanges control signals and the like with the use-side control unit 50a of the use unit 3a. Can be done.

As described above, the use side refrigerant circuits 13a, 13b, 13c, 13d, the heat source side refrigerant circuit 12, the refrigerant communication tubes 7, 8, 9 and the connection side refrigerant circuits 14a, 14b, 14c, 14d are connected. Thus, the refrigerant circuit 10 of the cooling and heating simultaneous operation type air conditioner 1 is configured. In the cooling and heating simultaneous operation type air conditioner 1, the heat source unit 2 including the compressor 21, the heat source side heat exchangers 24 and 25, and the receiver 28, the use side flow rate adjustment valves 51a, 51b, 51c, and 51d and the use side. Use units 3a, 3b, 3c, 3d having heat exchangers 52a, 52b, 52c, 52d constitute a refrigeration apparatus connected via gas refrigerant communication pipes 8, 9 and liquid refrigerant communication pipe 7. Yes. And, as will be described later, in the operation in which the use side heat exchangers 52a, 52b, 52c, 52d function as a refrigerant radiator, such as heating operation, the use side heat exchangers 52a, 52b, 52c, Based on the supercooling degree SC of the refrigerant at the outlet 52d, supercooling degree control is performed to control the opening degree of the use side flow rate adjusting valves 51a, 51b, 51c, 51d. In addition, the receiver 28 is provided with a receiver degassing pipe 41 that connects the upper part of the receiver 28 and the suction side of the compressor 21, and the receiver degassing pipe 41 is provided with a degassing side flow rate adjustment valve 42 that can adjust the opening degree. Provided.

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

The refrigeration cycle operation of the cooling / heating simultaneous operation type air conditioner 1 includes a cooling operation, a heating operation, a cooling / heating simultaneous operation (evaporation load main), and a cooling / heating simultaneous operation (heat radiation load main). Here, in the cooling operation, there is only a use unit that performs a cooling operation (that is, an operation in which the use-side heat exchanger functions as an evaporator of the refrigerant), and the heat source-side heat exchanger with respect to the evaporation load of the entire use unit In this operation, 24 and 25 are made to function as refrigerant radiators. In the heating operation, there are only use units that perform the heating operation (that is, the operation in which the use-side heat exchanger functions as a refrigerant radiator), and the main heat source side heat exchanger is used for the heat radiation load of the entire use unit. In this operation, the heat source side heat exchangers 24 and 25 function as a refrigerant evaporator. Simultaneous cooling and heating operation (evaporation load mainly) is a cooling unit (that is, an operation in which the use side heat exchanger functions as a refrigerant evaporator) and a heating unit (ie, the use side heat exchanger is a refrigerant radiator). When there is a mixture of utilization units that perform the operation that functions as the main unit and the heat load of the entire utilization unit is mainly the evaporation load, the heat source side heat as the main heat source side heat exchanger with respect to the evaporation load of the entire utilization unit In this operation, the exchangers 24 and 25 function as refrigerant radiators. Simultaneous cooling and heating operation (mainly heat radiation load) is a cooling unit (that is, an operation in which the use side heat exchanger functions as a refrigerant evaporator) and a heating unit (that is, the use side heat exchanger is a refrigerant radiator). When the heat load of the entire utilization unit is mainly the heat radiation load, the heat source side heat as the main heat source side heat exchanger is used for the heat radiation load of the entire utilization unit. This is an operation in which the exchangers 24 and 25 function as a refrigerant evaporator.

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

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

Specifically, in the heat source unit 2, the first heat exchange switching mechanism 22 is switched to the heat radiation operation state (the state indicated by the solid line of the first heat exchange switching mechanism 22 in FIG. 3), and the second heat exchange switching mechanism 22 The heat source side heat exchangers 24 and 25 are caused to function as refrigerant radiators by switching the operation state to the heat radiation operation state (the state indicated by the solid line of the second heat exchange switching mechanism 23 in FIG. 3). . Further, the high / low pressure switching mechanism 30 is switched to the evaporative load operation state (the state indicated by the solid line of the high / low pressure switching mechanism 30 in FIG. 3). Further, the opening amounts of the heat source side flow rate adjusting valves 26 and 27 are adjusted, and the receiver inlet opening / closing valve 28c is in an open state. Moreover, the opening degree of the refrigerant cooling side flow rate adjustment valve 37 is adjusted so that the high-pressure gas refrigerant discharged from the compressor 21 flows into the precooling heat exchanger 35. The suction return side flow rate adjustment valve 47 is adjusted in opening so that the supercooling heat exchanger 45 functions as a refrigerant cooler flowing through the receiver outlet pipe 28b. Further, here, since the use side heat exchanger functioning as a refrigerant radiator does not exist, the degassing side flow rate adjustment valve 42 is opened in a fully closed state (opening degree 0%) as described later. Thus, the gas refrigerant is not extracted from the receiver 28 to the suction side of the compressor 21 through the receiver gas vent pipe 41. In the connection units 4a, 4b, 4c and 4d, the use units 3a and 3b are opened by opening the high pressure gas on / off valves 66a, 66b, 66c and 66d and the low pressure gas on / off valves 67a, 67b, 67c and 67d. 3c, 3d use side heat exchangers 52a, 52b, 52c, 52d all function as refrigerant evaporators, and use units 3a, 3b, 3c, 3d use side heat exchangers 52a, 52b, 52c, All of 52d and the suction side of the compressor 21 of the heat source unit 2 are connected via the high and low pressure gas refrigerant communication pipe 8 and the low pressure gas refrigerant communication pipe 9. In the usage units 3a, 3b, 3c and 3d, the usage-side flow rate adjustment valves 51a, 51b, 51c and 51d are adjusted in opening.

In such a refrigerant circuit 10, the high-pressure gas refrigerant compressed and discharged by the compressor 21 is sent to the heat source side heat exchangers 24 and 25 as main heat source side heat exchangers through the heat exchange switching mechanisms 22 and 23. It is done. The high-pressure gas refrigerant compressed and discharged by the compressor 21 is also sent to the precooling heat exchanger 35 via the refrigerant heater 44. The high-pressure gas refrigerant sent to the heat source side heat exchangers 24 and 25 radiates heat by exchanging heat with outdoor air as a heat source supplied by the outdoor fan 34 in the heat source side heat exchangers 24 and 25. To do. The refrigerant that has radiated heat in the heat source side heat exchangers 24 and 25 is adjusted in flow rate in the heat source side flow rate adjusting valves 26 and 27, and then merges and passes through the inlet check valve 29a and the receiver inlet on / off valve 28c. Sent to. The high-pressure gas refrigerant sent to the precooling heat exchanger 35 also dissipates heat by exchanging heat with outdoor air as a heat source supplied by the outdoor fan 34 in the precooling heat exchanger 35. And the refrigerant | coolant thermally radiated in the pre-cooling heat exchanger 35 is sent to the refrigerant | coolant cooler 36, and cools the electrical component 20a. The refrigerant that has passed through the refrigerant cooler 36 is adjusted in flow rate by the refrigerant cooling side flow rate adjustment valve 37 and then sent to the receiver outlet pipe 28b. The refrigerant sent to the receiver 28 is temporarily stored in the receiver 28, and then sent to the receiver outlet pipe 28b. A part of the refrigerant is branched to the suction return pipe 46, and then the refrigerant cooler 36 is connected. The refrigerant that has passed through is joined to the supercooling heat exchanger 45. The refrigerant flowing through the receiver outlet pipe 28 b sent to the supercooling heat exchanger 45 is cooled by the refrigerant whose flow rate is adjusted by the suction return side flow rate adjustment valve 47 of the suction return pipe 46. The refrigerant flowing through the receiver outlet pipe 28 b cooled in the supercooling heat exchanger 45 is sent to the liquid refrigerant communication pipe 7 through the outlet check valve 29 c and the liquid side closing valve 31. On the other hand, the refrigerant flowing through the suction return pipe 46 after heat exchange in the subcooling heat exchanger 45 is returned to the suction side of the compressor 21.

The refrigerant sent to the liquid refrigerant communication tube 7 is branched into four and sent to the liquid connection tubes 61a, 61b, 61c, 61d of the connection units 4a, 4b, 4c, 4d. The refrigerant sent to the liquid connection pipes 61a, 61b, 61c, 61d is sent to the usage-side flow rate adjustment valves 51a, 51b, 51c, 51d of the usage units 3a, 3b, 3c, 3d.

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

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

Then, the low-pressure gas refrigerant sent to the gas refrigerant communication pipes 8 and 9 is returned to the suction side of the compressor 21 through the gas- side stop valves 32 and 33 and the high-low pressure switching mechanism 30.

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

-Heating operation-
In the heating operation, for example, all of the usage units 3a, 3b, 3c, and 3d perform the heating operation (that is, the operation in which all of the usage- side heat exchangers 52a, 52b, 52c, and 52d function as a refrigerant radiator). When the heat source side heat exchangers 24 and 25 as the main heat source side heat exchanger function as a refrigerant evaporator, the refrigerant circuit 10 of the air conditioner 1 is configured as shown in FIG. (For the flow, see the arrow attached to the refrigerant circuit 10 in FIG. 4).

Specifically, in the heat source unit 2, the first heat exchange switching mechanism 22 is switched to the evaporation operation state (the state indicated by the broken line of the first heat exchange switching mechanism 22 in FIG. 4), and the second heat exchange switching mechanism is selected. The heat source side heat exchangers 24 and 25 are caused to function as a refrigerant evaporator by switching the operation state to the evaporation operation state (the state indicated by the broken line of the second heat exchange switching mechanism 23 in FIG. 4). . Further, the high / low pressure switching mechanism 30 is switched to the heat radiation load operation state (the state indicated by the broken line of the high / low pressure switching mechanism 30 in FIG. 4). Further, the opening amounts of the heat source side flow rate adjusting valves 26 and 27 are adjusted, and the receiver inlet opening / closing valve 28c is in an open state. Moreover, the opening degree of the refrigerant cooling side flow rate adjustment valve 37 is adjusted so that the high-pressure gas refrigerant discharged from the compressor 21 flows into the precooling heat exchanger 35. The suction return side flow rate adjustment valve 47 is adjusted in opening so that the supercooling heat exchanger 45 functions as a refrigerant cooler flowing through the receiver outlet pipe 28b. In addition, here, since the use side heat exchangers 52a, 52b, 52c, and 52d that function as a refrigerant radiator exist, the degassing side flow rate adjustment valve 42 uses the use side flow rate adjustment as described later. The opening degree is adjusted in accordance with the control status of the valves 51 a, 51 b, 51 c, 51 d, and the gas refrigerant is extracted from the receiver 28 through the receiver gas vent pipe 41 to the suction side of the compressor 21. In the connection units 4a, 4b, 4c, and 4d, the high pressure gas on / off valves 66a, 66b, 66c, and 66d are opened, and the low pressure gas on / off valves 67a, 67b, 67c, and 67d are closed, thereby using the use unit 3a. 3b, 3c, 3d use side heat exchangers 52a, 52b, 52c, 52d all function as refrigerant radiators, and use units 3a, 3b, 3c, 3d use side heat exchangers 52a, 52b, All of 52c and 52d and the discharge side of the compressor 21 of the heat source unit 2 are connected via the high and low pressure gas refrigerant communication pipe 8. In the usage units 3a, 3b, 3c, and 3d, the usage-side flow rate adjustment valves 51a, 51b, 51c, and 51d are, as will be described later, supercooling of the refrigerant at the outlets of the usage- side heat exchangers 52a, 52b, 52c, and 52d. The degree of opening is adjusted by supercooling degree control that controls the degree of opening based on the degree SC.

In such a refrigerant circuit 10, the high-pressure gas refrigerant compressed and discharged by the compressor 21 is sent to the high-low pressure gas refrigerant communication pipe 8 through the high-low pressure switching mechanism 30 and the high-low pressure gas side closing valve 32. The high-pressure gas refrigerant compressed and discharged by the compressor 21 is also sent to the refrigerant heater 44. Here, when the opening degree of the degassing side flow rate adjustment valve 42 is adjusted to the open state, the gas refrigerant is extracted from the receiver 28 through the receiver degassing pipe 41, and thus the high pressure sent to the refrigerant heater 44. The gas refrigerant is cooled by exchanging heat with the refrigerant flowing through the receiver degassing pipe 41. On the other hand, the gas refrigerant flowing through the receiver degassing pipe 41 is heated and returned to the suction side of the compressor 21. Then, the refrigerant cooled in the refrigerant heater 44 is sent to the precooling heat exchanger 35. The high-pressure refrigerant sent to the precooling heat exchanger 35 radiates heat by exchanging heat with outdoor air as a heat source supplied by the outdoor fan 34 in the precooling heat exchanger 35. And the refrigerant | coolant thermally radiated in the pre-cooling heat exchanger 35 is sent to the refrigerant | coolant cooler 36, and cools the electrical component 20a. The refrigerant that has passed through the refrigerant cooler 36 is adjusted in flow rate by the refrigerant cooling side flow rate adjustment valve 37 and then sent to the receiver outlet pipe 28b.

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

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

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

The refrigerant sent to the liquid refrigerant communication tube 7 is sent to the receiver 28 through the liquid side closing valve 31, the inlet check valve 29b, and the receiver inlet opening / closing valve 28c. Here, when the opening degree of the degassing flow rate adjustment valve 42 is adjusted to the open state, the refrigerant sent to the receiver 28 is temporarily stored in the receiver 28 and separated into gas and liquid, The gas refrigerant is extracted to the suction side of the compressor 21 through the receiver gas vent pipe 41, and the liquid refrigerant is sent to the receiver outlet pipe 28b. A part of the refrigerant sent to the receiver outlet pipe 28 b is branched into the suction return pipe 46, and then merged with the refrigerant passed through the refrigerant cooler 36 and sent to the supercooling heat exchanger 45. The refrigerant flowing through the receiver outlet pipe 28 b sent to the supercooling heat exchanger 45 is cooled by the refrigerant whose flow rate is adjusted by the suction return side flow rate adjustment valve 47 of the suction return pipe 46. The refrigerant flowing through the receiver outlet pipe 28b cooled in the supercooling heat exchanger 45 is sent to both the heat source side flow rate adjusting valves 26 and 27 through the outlet check valve 29d. The refrigerant sent to the heat source side flow rate adjustment valves 26, 27 is adjusted in flow rate in the heat source side flow rate adjustment valves 26, 27, and then is supplied to the outdoor source 34 by the outdoor fan 34 in the heat source side heat exchangers 24, 25. By evaporating with air, it evaporates into a low-pressure gas refrigerant and is sent to the heat exchange switching mechanisms 22 and 23. The low-pressure gas refrigerant sent to the heat exchange switching mechanisms 22 and 23 merges and returns to the suction side of the compressor 21.

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

-Simultaneous cooling and heating operation (mainly evaporation load)-
In simultaneous cooling and heating operation (evaporation load mainly), for example, the usage units 3a, 3b, and 3c are in cooling operation, and the usage unit 3d is in heating operation (that is, the usage- side heat exchangers 52a, 52b, and 52c are refrigerants). The first heat source side heat exchanger 24 as a main heat source side heat exchanger functions as a refrigerant heat radiator and the use side heat exchanger 52d functions as a refrigerant heat radiator. In doing so, the refrigerant circuit 10 of the air conditioner 1 is configured as shown in FIG. 5 (refer to the arrows attached to the refrigerant circuit 10 of FIG. 5 for the flow of the refrigerant).

Specifically, in the heat source unit 2, the first heat exchange switching mechanism 22 is switched to the heat radiation operation state (the state indicated by the solid line of the first heat exchange switching mechanism 22 in FIG. 5), thereby Only the heat exchanger 24 is made to function as a refrigerant radiator. Further, the high / low pressure switching mechanism 30 is switched to the heat radiation load operation state (the state indicated by the broken line of the high / low pressure switching mechanism 30 in FIG. 5). Further, the opening degree of the first heat source side flow rate adjustment valve 26 is adjusted, the second heat source side flow rate adjustment valve 27 is in a closed state, and the receiver inlet on-off valve 28c is in an open state. Furthermore, since the use side heat exchanger 52d that functions as a refrigerant radiator is present here, the degassing side flow rate adjustment valve 42 is, as will be described later, the use side flow rate adjustment valves 51a, 51b, 51c. , The opening degree is adjusted according to the control status of 51d, but the result is that the refrigerant is not sent from the use units 3a, 3b, 3c, and 3d to the heat source unit 2 via the liquid refrigerant communication tube 7. Therefore, the opening degree is adjusted to a fully closed state (opening degree 0%), and thereby, the gas refrigerant is not extracted from the receiver 28 to the suction side of the compressor 21 through the receiver gas vent pipe 41. . In the connection units 4a, 4b, 4c, and 4d, the high-pressure gas on-off valve 66d and the low-pressure gas on-off valves 67a, 67b, and 67c are opened, and the high-pressure gas on-off valves 66a, 66b, 66c, and the low-pressure gas By closing the on-off valve 67d, the use side heat exchangers 52a, 52b, 52c of the use units 3a, 3b, 3c function as a refrigerant evaporator, and the use side heat exchanger 52d of the use unit 3d. Through the low-pressure gas refrigerant communication pipe 9 between the utilization side heat exchangers 52a, 52b, 52c of the utilization units 3a, 3b, 3c and the suction side of the compressor 21 of the heat source unit 2. The use side heat exchanger 52d of the use unit 3d and the discharge side of the compressor 21 of the heat source unit 2 are connected to the high / low pressure gas refrigerant communication pipe 8 in a connected state. To have become the connected state. In the usage units 3a, 3b, and 3c that perform the cooling operation, the opening amounts of the usage-side flow rate adjustment valves 51a, 51b, and 51c are adjusted. In the usage unit 3d that performs the heating operation, the usage-side flow rate adjustment valve 51d is described later. As described above, the opening degree is adjusted by the supercooling degree control that controls the opening degree based on the supercooling degree SC of the refrigerant at the outlet of the use side heat exchanger 52d.

In such a refrigerant circuit 10, a part of the high-pressure gas refrigerant compressed and discharged by the compressor 21 passes through the high / low pressure switching mechanism 30 and the high / low pressure gas side shut-off valve 32. The remainder is sent to the first heat source side heat exchanger 24 through the first heat exchange switching mechanism 22. The high-pressure gas refrigerant compressed and discharged by the compressor 21 is also sent to the precooling heat exchanger 35 via the refrigerant heater 44.

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

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

The high-pressure gas refrigerant sent to the first heat source side heat exchanger 24 dissipates heat by exchanging heat with outdoor air as a heat source supplied by the outdoor fan 34 in the first heat source side heat exchanger 24. To do. The refrigerant that has radiated heat in the first heat source side heat exchanger 24 is adjusted in flow rate in the first heat source side flow rate adjustment valve 26 and then sent to the receiver 28 through the inlet check valve 29a and the receiver inlet opening / closing valve 28c. The high-pressure gas refrigerant sent to the precooling heat exchanger 35 also dissipates heat by exchanging heat with outdoor air as a heat source supplied by the outdoor fan 34 in the precooling heat exchanger 35. And the refrigerant | coolant thermally radiated in the pre-cooling heat exchanger 35 is sent to the refrigerant | coolant cooler 36, and cools the electrical component 20a. The refrigerant that has passed through the refrigerant cooler 36 is adjusted in flow rate by the refrigerant cooling side flow rate adjustment valve 37 and then sent to the receiver outlet pipe 28b. The refrigerant sent to the receiver 28 is temporarily stored in the receiver 28, and then sent to the receiver outlet pipe 28b. A part of the refrigerant is branched to the suction return pipe 46, and then the refrigerant cooler 36 is connected. The refrigerant that has passed through is joined to the supercooling heat exchanger 45. The refrigerant flowing through the receiver outlet pipe 28 b sent to the supercooling heat exchanger 45 is cooled by the refrigerant whose flow rate is adjusted by the suction return side flow rate adjustment valve 47 of the suction return pipe 46. The refrigerant flowing through the receiver outlet pipe 28 b cooled in the supercooling heat exchanger 45 is sent to the liquid refrigerant communication pipe 7 through the outlet check valve 29 c and the liquid side closing valve 31. On the other hand, the refrigerant flowing through the suction return pipe 46 after heat exchange in the subcooling heat exchanger 45 is returned to the suction side of the compressor 21.

The refrigerant radiated in the use side heat exchanger 52d and sent to the liquid connection pipe 61d is sent to the liquid refrigerant communication pipe 7 and radiated in the first heat source side heat exchanger 24 to be radiated. It merges with the refrigerant sent to.

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

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

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

The low-pressure gas refrigerant sent to the low-pressure gas refrigerant communication tube 9 is returned to the suction side of the compressor 21 through the gas-side shut-off valve 33.

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

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

Specifically, in the heat source unit 2, the first heat exchange switching mechanism 22 is switched to the evaporation operation state (the state indicated by the broken line of the first heat exchange switching mechanism 22 in FIG. 6), thereby Only the heat exchanger 24 functions as a refrigerant evaporator. Further, the high / low pressure switching mechanism 30 is switched to the heat radiation load operation state (the state indicated by the broken line of the high / low pressure switching mechanism 30 in FIG. 6). Further, the opening degree of the first heat source side flow rate adjustment valve 26 is adjusted, the second heat source side flow rate adjustment valve 27 is in a closed state, and the receiver inlet on-off valve 28c is in an open state. Further, here, since the use side heat exchangers 52a, 52b, 52c functioning as a refrigerant radiator exist, the degassing side flow rate adjustment valve 42 is used as described later. , 51b, 51c, the opening degree is adjusted, and the gas refrigerant is extracted from the receiver 28 to the suction side of the compressor 21 through the receiver degassing pipe 41. In the connection units 4a, 4b, 4c and 4d, the high pressure gas on / off valves 66a, 66b and 66c and the low pressure gas on / off valve 67d are opened, and the high pressure gas on / off valve 66d and the low pressure gas on / off valve 67a, By closing 67b and 67c, the utilization side heat exchangers 52a, 52b and 52c of the utilization units 3a, 3b and 3c function as refrigerant radiators, and the utilization side heat exchanger 52d of the utilization unit 3d. As a refrigerant evaporator, the utilization side heat exchanger 52d of the utilization unit 3d and the suction side of the compressor 21 of the heat source unit 2 are connected via the low-pressure gas refrigerant communication pipe 9, and The use side heat exchangers 52a, 52b, 52c of the use units 3a, 3b, 3c and the discharge side of the compressor 21 of the heat source unit 2 connect the high / low pressure gas refrigerant communication pipe 8. To have become the connected state. In the usage unit 3d that performs the cooling operation, the usage-side flow rate adjustment valve 51d is adjusted in opening, and in the usage units 3a, 3b, and 3c that perform the heating operation, the usage-side flow rate adjustment valves 51a, 51b, and 51c are described later. As described above, the opening degree is adjusted by the supercooling degree control that controls the opening degree based on the supercooling degree SC of the refrigerant at the outlets of the use side heat exchangers 52a, 52b, and 52c.

In such a refrigerant circuit 10, the high-pressure gas refrigerant compressed and discharged by the compressor 21 is sent to the high-low pressure gas refrigerant communication pipe 8 through the high-low pressure switching mechanism 30 and the high-low pressure gas side closing valve 32. The high-pressure gas refrigerant compressed and discharged by the compressor 21 is also sent to the refrigerant heater 44. Here, when the opening degree of the degassing side flow rate adjustment valve 42 is adjusted to the open state, the gas refrigerant is extracted from the receiver 28 through the receiver degassing pipe 41, and thus the high pressure sent to the refrigerant heater 44. The gas refrigerant is cooled by exchanging heat with the refrigerant flowing through the receiver degassing pipe 41. On the other hand, the gas refrigerant flowing through the receiver degassing pipe 41 is heated and returned to the suction side of the compressor 21. Then, the refrigerant cooled in the refrigerant heater 44 is sent to the precooling heat exchanger 35. The high-pressure refrigerant sent to the precooling heat exchanger 35 radiates heat by exchanging heat with outdoor air as a heat source supplied by the outdoor fan 34 in the precooling heat exchanger 35. And the refrigerant | coolant thermally radiated in the pre-cooling heat exchanger 35 is sent to the refrigerant | coolant cooler 36, and cools the electrical component 20a. The refrigerant that has passed through the refrigerant cooler 36 is adjusted in flow rate by the refrigerant cooling side flow rate adjustment valve 37 and then sent to the receiver outlet pipe 28b.

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

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

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

A part of the refrigerant merged in the liquid refrigerant communication pipe 7 is sent to the liquid connection pipe 61d of the connection unit 4d, and the rest passes through the liquid side closing valve 31, the inlet check valve 29b, and the receiver inlet opening / closing valve 28c. It is sent to the receiver 28.

Then, the refrigerant sent to the liquid connection pipe 61d of the connection unit 4d is sent to the use side flow rate adjustment valve 51d of the use unit 3d.

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

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

The low-pressure gas refrigerant sent to the low-pressure gas refrigerant communication tube 9 is returned to the suction side of the compressor 21 through the gas-side shut-off valve 33.

Here, when the opening degree of the degassing side flow rate adjustment valve 42 is adjusted to the open state, the refrigerant sent to the receiver 28 is temporarily stored in the receiver 28 and separated into gas and liquid. Thereafter, the gas refrigerant is extracted to the suction side of the compressor 21 through the receiver gas vent pipe 41, and the liquid refrigerant is sent to the receiver outlet pipe 28b. A part of the refrigerant sent to the receiver outlet pipe 28 b is branched into the suction return pipe 46, and then merged with the refrigerant passed through the refrigerant cooler 36 and sent to the supercooling heat exchanger 45. The refrigerant flowing through the receiver outlet pipe 28 b sent to the supercooling heat exchanger 45 is cooled by the refrigerant whose flow rate is adjusted by the suction return side flow rate adjustment valve 47 of the suction return pipe 46. The refrigerant flowing through the receiver outlet pipe 28b cooled in the supercooling heat exchanger 45 is sent to the first heat source side flow rate adjustment valve 26 through the outlet check valve 29d. The refrigerant sent to the first heat source side flow rate adjustment valve 26 is adjusted in flow rate in the first heat source side flow rate adjustment valve 26, and then is supplied to the outdoor side supplied by the outdoor fan 34 in the first heat source side heat exchanger 24. By evaporating with air, it evaporates into a low-pressure gas refrigerant and is sent to the first heat exchange switching mechanism 22. The low-pressure gas refrigerant sent to the first heat exchange switching mechanism 22 merges with the low-pressure gas refrigerant returned to the suction side of the compressor 21 through the low-pressure gas refrigerant communication tube 9 and the gas-side shut-off valve 33, Returned to the suction side of the compressor 21.

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

-Supercooling control by use side flow control valve-
In the above-described various refrigeration cycle operations except the cooling operation (heating operation and simultaneous cooling and heating operation), an operation in which at least one of the use side heat exchangers 52a, 52b, 52c, 52d functions as a refrigerant radiator, That is, at least one of the usage units 3a, 3b, 3c, and 3d is performing the heating operation. And in the utilization unit which performs heating operation, the opening degree of utilization side flow control valve 51a, 51b, 51c, 51d based on the supercooling degree SC of the refrigerant | coolant in the exit of utilization side heat exchanger 52a, 52b, 52c, 52d. Supercooling degree control for controlling the MV is performed. And by this supercooling degree control, the flow rate of the refrigerant | coolant which flows through the utilization side heat exchanger 52a, 52b, 52c, 52d of utilization unit 3a, 3b, 3c, 3d which performs heating operation is adjusted, and desired heating capability is ensured. Like to do.

Specifically, in this supercooling degree control, it is used so that the supercooling degree SC at the outlets of the use side heat exchangers 52a, 52b, 52c, and 52d functioning as refrigerant radiators approaches the target supercooling degree SCt. The opening degree MV of the side flow rate adjusting valves 51a, 51b, 51c, 51d is controlled. Here, the refrigerant subcooling degree SC at the outlets of the use side heat exchangers 52a, 52b, 52c, and 52d is obtained by converting the refrigerant pressure on the discharge side of the compressor 21 detected by the discharge pressure sensor 73 into a saturation temperature. The refrigerant temperature Tirl on the liquid side of the use side heat exchangers 52a, 52b, 52c, 52d detected by the liquid side temperature sensors 82a, 82b, 82c, 82d is subtracted from the condensation temperature Tc obtained in this way. The target subcooling degree SCt is set to a value suitable for exhibiting the heat exchange performance of the use side heat exchangers 52a, 52b, 52c, and 52d. When the degree of supercooling SC is larger than the target degree of supercooling SCt, the opening MV of the use side flow rate adjustment valves 51a, 51b, 51c, 51d is increased within the range of the variable width in the supercooling degree control. Take control. When the degree of supercooling SC is smaller than the target degree of supercooling SCt, the opening MV of the use side flow rate adjustment valves 51a, 51b, 51c, 51d is made smaller within the range of the variable width in the supercooling degree control. Take control. Here, the variable width of the opening degree MV of the use side flow rate adjustment valves 51a, 51b, 51c, 51d in the supercooling degree control is the supercooling degree control lower limit opening degree MVm (for example, the opening degree 0% to Several degree) to a supercooling degree control upper limit opening degree MVx (for example, opening degree 100%) close to a fully opened state. For this reason, in the degree of supercooling control, each usage side is set so that the degree of supercooling SC at the outlets of the use side heat exchangers 52a, 52b, 52c, and 52d functioning as a refrigerant radiator approaches the target degree of supercooling SCt. The opening degree MV of the flow rate adjusting valves 51a, 51b, 51c, 51d is controlled within the range of the variable range from the supercooling degree control lower limit opening degree MVm to the supercooling degree control upper limit opening degree MVx.

-Receiver degassing control when fluid pressure loss is large-
As described above, in the cooling / heating simultaneous operation type air conditioner 1, an operation in which at least one of the usage- side heat exchangers 52 a, 52 b, 52 c, 52 d functions as a refrigerant radiator (here, heating operation and simultaneous cooling / heating operation). ), The degree of supercooling is controlled by the use side flow control valves 51a, 51b, 51c, 51d.

However, since the length of the liquid refrigerant communication tube 7 and the like vary depending on the installation conditions and construction status of the cooling and heating simultaneous operation type air conditioner 1, when at least one of the usage units 3a, 3b, 3c, and 3d performs the heating operation, The pressure loss (liquid pressure loss) of the liquid refrigerant flowing through the refrigerant communication tube 7 may increase. For this reason, the liquid refrigerant sent from the utilization units 3a, 3b, 3c, and 3d to the heat source unit 2 via the liquid refrigerant communication pipe 7 is reduced in pressure according to the liquid pressure loss, and the receiver 28 is in a liquid saturated state. The refrigerant at the outlets of the use side heat exchangers 52a, 52b, 52c, and 52d has a supercooling degree SC corresponding to the liquid pressure loss. For example, when the usage units 3a, 3b, 3c, and 3d perform the heating operation in a state where the opening degree of the degassing side flow rate adjustment valve 42 is adjusted to the fully closed state (opening degree 0%), on the Mollier diagram of FIG. It becomes like the refrigeration cycle shown in. Here, the liquid refrigerant sent from the utilization units 3a, 3b, 3c, and 3d to the heat source unit 2 via the liquid refrigerant communication tube 7 has a pressure that decreases according to the liquid pressure loss as shown by a point D in FIG. As a result, the liquid is saturated in the receiver 28. And the refrigerant | coolant in the exit of utilization side heat exchanger 52a, 52b, 52c, 52d will increase the degree of supercooling SC according to a hydraulic pressure loss, as shown to the point C of FIG. And the degree of supercooling SC of the refrigerant at the outlets of the use side heat exchangers 52a, 52b, 52c, 52d exceeds the variable width of the use side flow rate adjustment valves 51a, 51b, 51c, 51d, so that the degree of supercooling cannot be controlled. If it becomes excessively large, the heat dissipation capability of the use side heat exchangers 52a, 52b, 52c, 52d may be reduced, and the heating capability of the use units 3a, 3b, 3c, 3d may be reduced. That is, if the conditions under which the usage-side flow rate adjustment valves 51a, 51b, 51c, 51d can perform the supercooling degree control are the supercooling degree control normal conditions, The supercooling degree SC of the refrigerant at the outlets of the use side heat exchangers 52a, 52b, 52c, 52d becomes larger than the desired supercooling degree (here, the target supercooling degree SCt), and the use side flow control valves 51a, By simply controlling the opening MV of 51b, 51c, 51d, the supercooling degree SC of the refrigerant at the outlets of the use side heat exchangers 52a, 52b, 52c, 52d is set to the desired supercooling degree (here, the target supercooling degree). SCt) cannot be made smaller.

In order to eliminate such a situation, the pressure loss (liquid pressure loss) of the liquid refrigerant flowing through the liquid refrigerant communication pipe 7 is increased when at least one of the use units 3a, 3b, 3c, and 3d performs the heating operation. When the normal condition for the supercooling degree control is not satisfied, the refrigerant flowing into the receiver 28 is changed to the gas-liquid two-phase state, and the supercooling degree of the refrigerant at the outlets of the use side heat exchangers 52a, 52b, 52c, 52d. It is necessary to reduce the SC.

Therefore, here, the receiver 28 is provided with a receiver degassing pipe 41 that connects the upper part of the receiver 28 and the suction side of the compressor 21, and the receiver degassing pipe 41 has a degassing-side flow rate adjustment capable of adjusting the opening degree. A valve 42 is provided to control the opening degree MV of the degassing side flow rate adjustment valve 42 so as to satisfy the normal condition of supercooling degree control.

Next, the opening degree control of the gas vent side flow rate control valve 42 will be described with reference to FIGS. Here, FIG. 8 is a Mollier diagram showing a refrigeration cycle in the case where the heating operation is performed with the degassing side flow rate adjustment valve 42 opened, and FIG. 9 shows the opening degree of the degassing side flow rate adjustment valve 42. It is a flowchart of control. Various operations including the opening degree control of the gas vent side flow rate adjustment valve 42 described here are performed by the control units 20, 50a, 50b, 50c, 50d, 60a, 60b, 60c, 60d.

First, in step ST1, it is determined whether or not the normal supercooling degree control normal condition is satisfied. That is, at least one of the usage units 3a, 3b, 3c, and 3d is performing a heating operation (that is, an operation in which at least one of the usage- side heat exchangers 52a, 52b, 52c, and 52d functions as a refrigerant radiator). Whether the usage-side flow rate control valves 51a, 51b, 51c, 51d of the usage units 3a, 3b, 3c, 3d that are performing the heating operation are performing the supercooling degree control, whether the supercooling degree control normal condition is satisfied Determine if. Here, the normal condition of the supercooling degree control is determined depending on whether or not the opening degree MV of the use side flow rate adjusting valves 51a, 51b, 51c, 51d performing the supercooling degree control is less than the supercooling degree control upper limit opening degree MVx. Judgment is made as to whether or not it is satisfied. That is, when the opening MV of the use side flow rate adjustment valves 51a, 51b, 51c, 51d is opened to the supercooling degree control upper limit opening MVx that is the upper limit opening in the supercooling degree control, The flow rate adjustment valves 51a, 51b, 51c, 51d are over the variable width, and the supercooling degree SC of the refrigerant at the outlets of the use side heat exchangers 52a, 52b, 52c, 52d cannot be controlled. It is considered that it is excessive. Here, when there are a plurality of use units performing the heating operation, it is determined whether or not the subcool degree control normal condition is satisfied for each use unit.

Next, when it is determined in step ST1 that the normal condition for supercooling degree control is not satisfied, the process proceeds to step ST2. And in step ST2, control which enlarges the opening degree MV of the degassing side flow control valve 42 is performed. Here, the opening degree MV of the degassing side flow rate adjustment valve 42 is controlled to be increased by adding the first opening change ΔMV1 to the current opening degree MV of the degassing side flow rate adjustment valve 42. Then, when the degassing side flow rate adjustment valve 42 is in the fully closed state (opening MV = 0%), the gas refrigerant begins to be extracted from the receiver 28 through the receiver degassing pipe 41, and the degassing side flow rate adjustment When the valve 42 is already open, the flow rate of the gas refrigerant extracted from the receiver 28 through the receiver degassing pipe 41 increases. Then, when the process of step ST2 is repeated, as shown at points C and D in FIG. 8, the state of the refrigerant flowing into the receiver 28 is changed to a gas-liquid two-phase state with a large amount of gas refrigerant, and the use side heat exchanger 52a. , 52b, 52c, 52d, the refrigerant subcooling degree SC at the outlets of the use side heat exchangers 52a, 52b, 52c, 52d is reduced. It is prevented that the supercooling degree control becomes too large to exceed the variable width of 51c and 51d, that is, the normal condition for supercooling degree control in step ST1 is satisfied.

Next, when it is determined in step ST1 that the normal supercooling degree control normal condition is satisfied, the process proceeds to step ST3. And in step ST3, control which makes the opening degree MV of the degassing side flow control valve 42 small is performed. Here, the opening degree MV of the degassing side flow rate adjustment valve 42 is controlled to be reduced by subtracting the second opening change ΔMV2 from the current opening degree MV of the degassing side flow rate adjustment valve 42. Then, when the degassing side flow rate adjustment valve 42 is in the fully closed state (opening MV = 0%), the opening is in the fully closed state, that is, the gas refrigerant is extracted from the receiver 28 through the receiver degassing pipe 41. In the case where the state where the gas is not discharged is maintained and the degassing side flow rate adjustment valve 42 is already opened by the process of step ST2, the flow rate of the gas refrigerant extracted from the receiver 28 through the receiver degassing pipe 41 is decreased. Become. When the process of step ST3 is repeated together with the process of step ST2, the degassing side flow rate adjustment valve 42 is controlled to open and close depending on whether the normal condition of the supercooling degree control of step ST1 is satisfied, and the degassing side flow rate adjustment is performed. The opening degree MV of the valve 42 can be maintained at the minimum opening degree necessary for satisfying the normal condition of the supercooling degree control.

As described above, the degassing side flow rate control valve 42 is controlled to open and close in steps ST2 and ST3 depending on whether or not the normal condition of the supercooling degree control in step ST1 is satisfied.

However, when the gas refrigerant is extracted from the receiver 28 by opening the gas vent side flow rate adjustment valve 42, the liquid level of the liquid refrigerant that accumulates in the receiver 28 may rise, and may rise to near full liquid.

Therefore, here, not only the processes of steps ST1, ST2, and ST3 but also the processes of steps ST4 and ST5 are performed. Specifically, when the receiver 28 reaches the predetermined liquid level L1 (see FIG. 2), regardless of whether or not the normal condition of the supercooling degree control in step ST1 is satisfied, that is, the supercooling degree control in step ST1. Even when the normal condition is not satisfied, control is performed to forcibly reduce the opening degree MV of the gas vent side flow rate adjustment valve 42. Here, the opening degree MV of the degassing side flow rate adjustment valve 42 is controlled to be reduced by subtracting the third opening change ΔMV3 from the current opening degree MV of the degassing side flow rate adjustment valve 42. Here, the third opening degree change ΔMV3 may be set to a value larger than the first opening degree change ΔMV1 and the second opening degree change ΔMV2 in order to be able to greatly limit the degassing amount. preferable.

It should be noted that various methods such as a liquid level sensor can be used to determine whether or not the receiver 28 has reached the predetermined liquid level L1, but here, the receiver liquid level detection tube 43 is used. The liquid level in the receiver 28 is detected by the receiver liquid level detection tube 43 as follows. First, the receiver liquid level detection pipe 43 extracts the refrigerant from the predetermined height position L1 of the receiver 28 as shown in FIGS. 2, 4 and 6 when the degassing side flow rate adjustment valve 42 is opened. Here, the refrigerant extracted from the receiver liquid level detection tube 43 is in a gas state when the liquid level in the receiver 28 is lower than the predetermined height position L1, and the liquid level in the receiver 28 is at a predetermined level. When the position is L1 or more, the liquid state is entered.

Next, the refrigerant extracted from the receiver liquid level detection tube 43 merges with the refrigerant extracted from the receiver degassing tube 41 as shown in FIGS. Here, the refrigerant extracted from the receiver degassing pipe 41 is in a gas state when the liquid level in the receiver 28 is lower than the height position L2 (see FIG. 2). For this reason, when the refrigerant extracted from the receiver liquid level detection tube 43 is in a gas state, the refrigerant flowing through the receiver degassing tube 41 after joining the refrigerant extracted from the receiver degassing tube 41 is also gas. It becomes a state. On the other hand, when the refrigerant extracted from the receiver liquid level detection tube 43 is in a liquid state, the refrigerant flowing through the receiver degassing tube 41 after joining the refrigerant extracted from the receiver degassing tube 41 is a gas refrigerant. It becomes a gas-liquid two-phase state in which liquid refrigerant is mixed. And the refrigerant | coolant which flows through the receiver degassing pipe | tube 41 after the refrigerant | coolant extracted from the receiver liquid level detection pipe | tube 43 merges is pressure-reduced by the degassing side flow control valve 42 to the pressure of the refrigerant | coolant in the suction side of the compressor 21. Is done. By the depressurization operation by the degassing flow rate control valve 42, the refrigerant flowing through the receiver degassing pipe 41 undergoes a temperature drop according to the state of the refrigerant before the depressurization operation. That is, when the refrigerant flowing through the receiver degassing pipe 41 is in a gas state, the temperature drop due to the decompression operation is small, and when it is in the gas-liquid two-phase state, the temperature drop due to the decompression operation is large. For this reason, although not employed here, the temperature of the refrigerant flowing through the receiver degassing pipe 41 after being depressurized by the degassing flow rate adjusting valve 42 was used to extract from the liquid level detection pipe 43. It can also be detected whether the refrigerant is in a liquid state (whether the liquid level in the receiver 28 has reached the height position L1).

Next, the refrigerant flowing through the receiver degassing pipe 41 after being depressurized by the degassing flow rate adjusting valve 42 is sent to the refrigerant heater 44 as shown in FIGS. Heat is exchanged with the high-pressure gas refrigerant flowing between the discharge side and the precooling heat exchanger 35 and heated. As a result of the heating operation by the refrigerant heater 44, the temperature of the refrigerant flowing through the receiver degassing pipe 41 is increased according to the state of the refrigerant before the heating operation. That is, when the refrigerant flowing through the receiver degassing pipe 41 after being depressurized by the degassing flow rate adjustment valve 42 is in a gas state, the temperature rise due to the heating operation is large, and the gas-liquid two-phase state is present. The temperature rise due to the decompression operation is reduced. Therefore, here, the temperature of the refrigerant flowing through the receiver degassing pipe 41 after being heated by the refrigerant heater 44 is detected by the degassing side temperature sensor 75, and this detected refrigerant temperature is used. Thus, it is detected whether the refrigerant extracted from the liquid level detection tube 43 is in a liquid state (whether the liquid level in the receiver 28 has reached the height position L1). Specifically, the refrigerant heater 44 is obtained by subtracting the refrigerant saturation temperature obtained by converting the refrigerant pressure detected by the suction pressure sensor 71 from the refrigerant temperature detected by the degassing temperature sensor 75. The degree of superheat of the refrigerant flowing through the receiver degassing pipe 41 after being heated at is obtained. When the superheat degree of the refrigerant is equal to or greater than the predetermined temperature difference, the refrigerant extracted from the liquid level detection tube 43 is in a gas state (the liquid level in the receiver 28 has reached the height position L1. If the superheat degree of the refrigerant does not reach a predetermined temperature difference, the refrigerant extracted from the liquid level detection tube 43 is in a liquid state (the liquid level in the receiver 28 is at a height position). L1 is reached).

In this way, here, an operation that causes at least one of the usage- side heat exchangers 52a, 52b, 52c, and 52d to function as a refrigerant radiator (heating operation and simultaneous cooling and heating shown in FIGS. 4, 5, and 6). In operation, the degree of opening of the degassing side flow rate adjusting valve 42 is set so as to satisfy the normal condition of supercooling degree control while performing the degree of supercooling degree control by the opening degree MV of the use side flow rate regulating valves 51a, 51b, 51c, 51d. The MV is controlled. In the simultaneous cooling / heating operation (mainly evaporative load) shown in FIG. 5, although there is a use unit 3d that performs heating operation, the heat load of the entire use units 3a, 3b, 3c, and 3d is mainly evaporative load. Yes, it is not an operation state in which the refrigerant is sent from the utilization units 3a, 3b, 3c, and 3d to the heat source unit 2 via the liquid refrigerant communication tube 7. For this reason, although the control of the above steps ST1 to ST5 is applied, there is no situation where the normal condition for the supercooling degree control is not satisfied. As a result, the degassing side flow rate control valve 42 is fully closed (opened). The degree of opening is adjusted to 0%), and the gas refrigerant is not extracted from the receiver 28 through the receiver degassing pipe 41 to the suction side of the compressor 21.

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

<A>
Here, as described above, the receiver degassing pipe 41 is provided with the degassing flow rate adjusting valve 42 capable of adjusting the opening degree, and the degassing side flow rate adjusting valve 42 is set so as to satisfy the normal condition of supercooling degree control. The opening is controlled. That is, by increasing the opening degree MV of the gas vent side flow rate control valve 42, the state of the refrigerant flowing into the receiver 28 is changed to a gas-liquid two-phase state with a large amount of gas refrigerant, and the use side heat exchangers 52a, 52b, 52c. , 52d, the refrigerant supercooling degree SC at the outlet is reduced, and the refrigerant supercooling degree SC at the outlet of the use side heat exchangers 52a, 52b, 52c, 52d is reduced to that of the use side flow control valves 51a, 51b, 51c, 51d. The excessive cooling is prevented so that the supercooling degree control cannot be performed beyond the variable width, that is, the normal condition of the supercooling degree control is satisfied.

Thereby, here, even when the hydraulic pressure loss is large, the supercooling degree control can be appropriately performed, and the decrease in the heating capacity can be suppressed.

<B>
Here, as described above, whether or not the normal condition of the supercooling degree control is satisfied depending on whether or not the opening degree MV of the use side flow rate adjustment valves 51a, 51b, 51c, 51d is less than the supercooling degree control upper limit opening degree MVx. Judgment is made. That is, when the opening MV of the use side flow rate adjustment valves 51a, 51b, 51c, 51d is opened to the supercooling degree control upper limit opening MVx that is the upper limit opening in the supercooling degree control, The flow rate adjustment valves 51a, 51b, 51c, 51d are over the variable width, and the supercooling degree SC of the refrigerant at the outlets of the use side heat exchangers 52a, 52b, 52c, 52d cannot be controlled. It is considered that it is excessive.

As a result, the opening MV of the use side flow rate adjusting valves 51a, 51b, 51c, 51d performing the supercooling degree control can be maintained below the supercooling degree control upper limit opening MVx. The degree of supercooling can be controlled within the range of the variable width of the control valves 51a, 51b, 51c, 51d.

<C>
Here, as described above, the degassing side flow rate adjustment valve 42 is controlled to open and close depending on whether or not the subcooling degree control normal condition is satisfied. For this reason, the opening degree MV of the degassing side flow rate adjustment valve 42 can be maintained at the minimum opening degree necessary for satisfying the normal condition of the supercooling degree control.

Thereby, the amount of the gas refrigerant extracted from the receiver 28 can be minimized here, and the performance degradation due to degassing from the receiver 28 can be suppressed.

<D>
Here, as described above, when the receiver 28 reaches the predetermined liquid level L1, it is a case where the normal condition for the supercooling degree control is not satisfied regardless of whether the normal condition for the supercooling degree control is satisfied. However, control is performed to forcibly reduce the opening degree MV of the gas vent side flow rate adjustment valve 42.

Thereby, here, it is possible to prevent the liquid refrigerant from returning from the receiver 28 to the compressor 21 while appropriately performing the supercooling degree control.

(4) Modifications In the above embodiment, the configuration example of the cooling and heating simultaneous operation type air conditioner 1 is described as a refrigeration apparatus to which the present invention is applied. However, the present invention is not limited to this. For example, even in other refrigeration apparatuses such as a cooling / heating switching operation type air conditioner, a heat source unit having a receiver, and a utilization unit having a utilization side flow rate adjustment valve and a utilization side heat exchanger have a refrigerant communication pipe. In the operation in which the use side heat exchanger functions as a refrigerant radiator, the opening degree of the use side flow rate control valve is controlled based on the degree of subcooling of the refrigerant at the outlet of the use side heat exchanger. The present invention can be applied to any device.

In the above embodiment, the supercooling heat exchanger 45 and the suction return pipe 46 are provided, but they may not be provided.

Furthermore, the heating source of the refrigerant heater 44 provided in the receiver liquid level detection pipe 43 is not limited to the high-pressure gas refrigerant discharged from the compressor 21, and may be a liquid refrigerant or the like flowing through the receiver outlet pipe 28b. Good.

In the present invention, a heat source unit having a receiver, a utilization unit having a utilization side flow rate adjustment valve and a utilization side heat exchanger are connected via a refrigerant communication pipe, and the utilization side heat exchanger is radiated of refrigerant. In the operation to function as a cooler, the present invention is widely applicable to a refrigeration apparatus that controls the opening degree of the use side flow rate control valve based on the degree of supercooling of the refrigerant at the outlet of the use side heat exchanger.

1 Cooling and heating simultaneous operation type air conditioner (refrigeration equipment)
2 Heat source unit 3a, 3b, 3c, 3d Utilization unit 7 Liquid refrigerant communication tube 8, 9 Gas refrigerant communication tube 21 Compressor 24, 25 Heat source side heat exchanger 28 Receiver 41 Receiver degassing tube 42 Degassing side flow rate adjustment valve 51a , 51b, 51c, 51d Use side flow rate adjustment valve 52a, 52b, 52c, 52d Use side heat exchanger

JP 2006-78026 A

Claims (4)

1. A heat source unit (2) having a compressor (21), a heat source side heat exchanger (24, 25), and a receiver (28), a use side flow rate adjustment valve (51a, 51b, 51c, 51d) and a use side heat exchange The utilization units (3a, 3b, 3c, 3d) having the containers (52a, 52b, 52c, 52d) are connected via the gas refrigerant communication pipe (8, 9) and the liquid refrigerant communication pipe (7). In the operation in which the use side heat exchanger functions as a refrigerant radiator, the supercooling that controls the opening degree of the use side flow control valve based on the degree of refrigerant subcooling at the outlet of the use side heat exchanger. In refrigeration equipment that performs degree control,
   The receiver is provided with a receiver vent pipe (41) for connecting the upper part of the receiver and the suction side of the compressor,
   The receiver degassing pipe is provided with a degassing flow rate control valve (42) capable of opening adjustment,
   The opening degree of the degassing side flow rate control valve is controlled so that the use side flow rate control valve performing the supercooling degree control satisfies the normal condition of the supercooling degree control capable of performing the supercooling degree control. To
   Refrigeration equipment (1).
2. The normal condition of the supercooling degree control is that the opening degree of the use side flow rate control valve (51a, 51b, 51c, 51d) performing the supercooling degree control is less than the supercooling degree control upper limit opening degree. ,
   The refrigeration apparatus (1) according to claim 1.
3. When the use side flow rate control valves (51a, 51b, 51c, 51d) performing the supercooling degree control satisfy the normal condition of the supercooling degree control, the degassing side flow rate control valve (42) is opened. Control to reduce the degree,
   When the use side flow rate control valve performing the supercooling degree control does not satisfy the normal condition of the supercooling degree control, the opening degree of the degassing side flow rate control valve is increased.
   The refrigeration apparatus (1) according to claim 1 or 2.
4. When the receiver (28) reaches a predetermined liquid level, control is performed to reduce the opening degree of the degassing side flow rate control valve (42) regardless of whether the normal condition for supercooling degree control is satisfied. ,
   The refrigeration apparatus (1) according to claim 3.

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