Air conditioning device

Abstract

An air conditioning device according to the present disclosure is a two-pipe simultaneous cooling and heating operation style air conditioning device comprising a plurality of indoor units, wherein the cooling operation and the heating operation can be performed independently for each of the indoor units, and two connection pipes are used to connect an outdoor unit and a relay unit. The air conditioning device according to the present disclosure comprises a relay flow path switching device in the relay unit. The relay flow path switching device is configured so as to switch a flow path of the relay flow path switching device when the flow path of a refrigerant in the outdoor unit has switched, and cause the open / closed condition of an opening / closing device that is connected to an indoor unit in which the operation mode is the same before and after the switching of the flow path of the refrigerant in the outdoor unit to be the same before and after the switching of the flow path of the refrigerant in the outdoor unit.

Description

air conditioning equipment

[0001] The present disclosure relates to an air conditioner equipped with multiple indoor units.

[0002] Conventionally, air conditioners equipped with multiple indoor units have been known. Among these air conditioners, there are also simultaneous cooling and heating operation air conditioners in which each indoor unit can perform cooling and heating operations independently. That is, a simultaneous cooling and heating operation air conditioner can perform heating operation with some indoor units and cooling operation with some indoor units. A simultaneous cooling and heating operation air conditioner includes an outdoor unit that is a heat source unit, a relay unit connected to the outdoor unit by connecting piping, and multiple indoor units connected to the relay unit by connecting piping. The outdoor unit is, for example, located outside the building. Furthermore, each of the indoor units is located inside the building.

[0003] Also known among conventional simultaneous cooling and heating operation air conditioners is a two-pipe simultaneous cooling and heating operation air conditioner in which two connecting pipes connect the outdoor unit and the relay unit. A two-pipe simultaneous cooling and heating operation air conditioner can use an outdoor unit with the same configuration as an outdoor unit of a non-simultaneous cooling and heating operation air conditioner. In this case, a first connecting pipe, which is one of the two connecting pipes, carries high-pressure liquid refrigerant that has flowed through the heat-source-side heat exchanger and the heat-source-side throttle device, or a low-pressure gas-liquid two-phase refrigerant that has passed through the heat-source-side throttle device and flows into the heat-source-side heat exchanger. A second connecting pipe, which is the other of the two connecting pipes, carries low-pressure gas refrigerant drawn into the compressor, or high-pressure gas refrigerant discharged from the compressor.

[0004] In a simultaneous cooling and heating operation air conditioner, the refrigerant flow path in the outdoor unit switches depending on whether the total cooling load of the multiple indoor units is greater than the heating load or whether the total heating load of the multiple indoor units is greater than the cooling load. Here, there may be indoor units whose operating mode is the same before and after the refrigerant flow path in the outdoor unit switches. Specifically, there may be indoor units whose operating mode remains the same in either the cooling or heating mode before and after the refrigerant flow path in the outdoor unit switches. When such indoor units exist, in a conventional two-pipe simultaneous cooling and heating operation air conditioner relay unit, when the refrigerant flow path in the outdoor unit switches, it is necessary to change the open / close state of multiple opening / closing devices connected to the indoor units and maintain the refrigerant flow direction in the indoor units in order to keep the indoor units in the same operating mode. For this reason, when the refrigerant flow path in the conventional two-pipe simultaneous cooling and heating operation air conditioner switches, abnormal noise due to the change in refrigerant flow, a decrease in the air conditioning capacity of the indoor units due to refrigerant pressure fluctuations, and a decrease in the performance of the air conditioner may occur.

[0005] Therefore, a conventional two-pipe simultaneous cooling and heating operation air conditioner has been proposed that suppresses changes in the open / close state of a switch connected to an indoor unit when the refrigerant flow path in the outdoor unit is switched (see Patent Document 1). Specifically, the two-pipe simultaneous cooling and heating operation air conditioner described in Patent Document 1 includes a refrigerant flow control unit between the outdoor unit and the relay unit. The refrigerant flow control unit and the relay unit are connected by two connecting pipes. Specifically, the refrigerant flow control unit and the relay unit are connected by a high-pressure connecting pipe through which a high-pressure refrigerant flows and a low-pressure connecting pipe through which a low-pressure refrigerant flows. The two-pipe simultaneous cooling and heating operation air conditioner described in Patent Document 1 is configured so that, regardless of the refrigerant flow path in the outdoor unit, the refrigerant flows from the refrigerant flow control unit to the relay unit through the high-pressure connecting pipe and from the relay unit to the refrigerant flow control unit through the low-pressure connecting pipe. As a result, the two-pipe simultaneous cooling and heating operation air conditioner described in Patent Document 1 suppresses changes in the open / close state of a switch connected to an indoor unit when the refrigerant flow path in the outdoor unit is switched.

[0006] Patent No. 5877632

[0007] In a conventional two-pipe simultaneous cooling and heating operation air conditioner that does not include a refrigerant flow control unit, gas refrigerant does not flow through the first connecting pipe, through which liquid refrigerant or two-phase gas-liquid refrigerant flows. On the other hand, in a two-pipe simultaneous cooling and heating operation air conditioner described in Patent Document 1 that includes a refrigerant flow control unit, high-pressure gas refrigerant also flows through the high-pressure connecting pipe, through which high-pressure liquid refrigerant flows. Therefore, the high-pressure connecting pipe used in the two-pipe simultaneous cooling and heating operation air conditioner described in Patent Document 1 has a larger diameter than the first connecting pipe used in a conventional two-pipe simultaneous cooling and heating operation air conditioner that does not include a refrigerant flow control unit. Therefore, the two-pipe simultaneous cooling and heating operation air conditioner described in Patent Document 1 requires a larger amount of refrigerant than a conventional two-pipe simultaneous cooling and heating operation air conditioner that does not include a refrigerant flow control unit. That is, conventional two-pipe simultaneous cooling and heating operation air conditioners that suppress changes in the open / close state of the opening / closing device connected to the indoor unit when the refrigerant flow path in the outdoor unit is switched have the problem of requiring a larger amount of refrigerant.

[0008] The present disclosure has been made to solve the above-mentioned problems, and aims to provide a two-pipe simultaneous heating and cooling air conditioning apparatus that can suppress changes in the open / close state of an opening / closing device connected to an indoor unit when the refrigerant flow path in the outdoor unit is switched, and can also suppress an increase in the amount of refrigerant sealed inside.

[0009] An air conditioning apparatus according to the present disclosure comprises an outdoor unit, a relay unit connected to the outdoor unit by first and second connection pipes, and a plurality of indoor units connected to the relay unit by connection pipes, the outdoor unit comprising a compressor that compresses and discharges a refrigerant, a heat source side heat exchanger that exchanges heat between outdoor air and the refrigerant, a heat source side throttling device connected to the heat source side heat exchanger and the first connection pipe and reducing the pressure of the refrigerant flowing between the heat source side heat exchanger and the first connection pipe, and a heat source side flow switching device that switches the flow path of the refrigerant flowing through the outdoor unit between a first heat source side flow path through which the refrigerant flows out to the first connection pipe and a second heat source side flow path through which the refrigerant flows out to the second connection pipe, each of the indoor units comprising a load side heat exchanger that exchanges heat between a load side heat medium and the refrigerant, and a load side throttling device connected to the load side heat exchanger and reducing the pressure of the refrigerant to adjust the amount of refrigerant flowing to the load side heat exchanger, and a relay flow path switching device connected to each of the first connecting pipe, the second connecting pipe, and the opening and closing device, each of which is connected to a connection port on the opposite side to the connection port to which the load side throttle device is connected in any of the load side heat exchangers, and which has an outflow path through which refrigerant flows from the relay unit to the load side heat exchanger and an inflow path through which refrigerant flows from the load side heat exchanger to the relay unit, and which closes the inflow path when the outflow path is open and opens the inflow path when the outflow path is closed, and which is connected to a connection port on the opposite side to the connection port to which the load side throttle device is connected in any of the load side heat exchangers, and which has an outflow path through which refrigerant flows from the relay unit to the load side heat exchanger and an inflow path through which refrigerant flows from the load side heat exchanger to the relay unit, and which is connected to a connection port on the opposite side to the connection port to which the load side throttle device is connected in any of the load side heat exchangers, and which closes the inflow path when the outflow path is open and opens the inflow path when the outflow path is closed, and which is connected to a connection port on the opposite side to the connection port to which the load side throttle device is connected in any of the load side heat exchangers, and which

[0010] In the air conditioning apparatus according to the present disclosure, when the refrigerant flow path in the outdoor unit is switched, the relay flow path switching device can suppress changes in the open / close state of the opening / closing device connected to the indoor unit. Furthermore, the air conditioning apparatus according to the present disclosure can be configured so that gas refrigerant does not flow through the first connecting pipe, thereby suppressing an increase in the diameter of the first connecting pipe. Therefore, the air conditioning apparatus according to the present disclosure can also suppress an increase in the amount of refrigerant sealed inside.

[0011] FIG. 1 is a refrigerant circuit diagram showing an example of a circuit configuration of an air conditioner according to Embodiment 1 in a cooling-dominated operation mode. FIG. 2 is a refrigerant circuit diagram showing the flow of refrigerant in a cooling-dominated operation mode of an air conditioner according to Embodiment 1. FIG. 3 is a refrigerant circuit diagram showing the flow of refrigerant in a heating-dominated operation mode of an air conditioner according to Embodiment 1. FIG. 4 is a refrigerant circuit diagram showing the flow of refrigerant in a heating-dominated operation mode of an air conditioner according to Embodiment 1. FIG. 5 is a refrigerant circuit diagram showing an example of a circuit configuration of an air conditioner according to Embodiment 2 in a cooling-dominated operation mode. FIG. 6 is a refrigerant circuit diagram showing an example of a circuit configuration of an air conditioner according to Embodiment 2 in a cooling-dominated operation mode. FIG. 7 is a refrigerant circuit diagram showing an example of a circuit configuration of an air conditioner according to Embodiment 3 in a heating-dominated operation mode. FIG. 8 is a refrigerant circuit diagram showing an example of a circuit configuration of an air conditioner according to Embodiment 3 in a heating-dominated operation mode. FIG. 9 is a refrigerant circuit diagram showing an example of a circuit configuration of an air conditioner according to Embodiment 4 in a heating-dominated operation mode.

[0012] Below, an embodiment of an air conditioning device according to the present disclosure is described based on the drawings. In each drawing, the same reference numerals are used to denote the same or equivalent parts, and this is common throughout the entire specification. Furthermore, the forms of the components shown in the entire specification are merely examples. The air conditioning device according to the present disclosure is not limited to the description of the following embodiment.

[0013] Embodiment 1. Fig. 1 is a refrigerant circuit diagram showing an example of the circuit configuration of an air conditioning apparatus according to embodiment 1 in a cooling-only operation mode. The black arrows shown in Fig. 1 indicate the direction of refrigerant flow when the air conditioning apparatus 100 executes the cooling-only operation mode described below. Note that in Fig. 1 and Fig. 2 and subsequent figures, when showing opening and closing devices, opening and closing devices in an open state are shown in white, and opening and closing devices in a closed state are shown in black.

[0014] [Configuration of Air Conditioning Apparatus 100] The air conditioning apparatus 100 circulates a refrigerant and performs air conditioning using a refrigeration cycle. The air conditioning apparatus 100 includes an outdoor unit 101, a relay unit 102, and multiple indoor units 103. Note that, below, when each indoor unit 103 is to be distinguished, an alphabet will be added to the end of its reference numeral. Similarly, when the components included in each indoor unit 103 are to be distinguished, the same alphabet will be added to the end of the reference numeral as the indoor unit 103. Similarly, when the components connected to each indoor unit 103 are to be distinguished, the same alphabet will be added to the end of the reference numeral as the indoor unit 103. FIG. 1 illustrates an example of an air conditioning apparatus 100 equipped with four indoor units 103. In other words, FIG. 1 illustrates an air conditioning apparatus 100 equipped with indoor units 103a to 103d. However, the number of indoor units 103 included in the air conditioning apparatus 100 is not limited to four, as long as it is plural.

[0015] The outdoor unit 101 and the relay unit 102 are connected by two connecting pipes. Specifically, the outdoor unit 101 and the relay unit 102 are connected by a first connecting pipe 7 and a second connecting pipe 8. Furthermore, each of the indoor units 103 is connected to the relay unit 102 by two connecting pipes. Specifically, each of the indoor units 103 is connected to the relay unit 102 by a connecting pipe 9a and a connecting pipe 9b. Each of the indoor units 103 is connected in parallel to the relay unit 102.

[0016] Each indoor unit 103 can execute a cooling operation mode and a heating operation mode as its operating mode. The cooling operation mode is an operation mode in which the indoor unit 103 performs cooling operation. The heating operation mode is an operation mode in which the indoor unit 103 performs heating operation. The air conditioning apparatus 100 is configured to allow selection of an all-cooling operation mode, an all-heating operation mode, a cooling-dominated operation mode, and a heating-dominated operation mode as its operating modes. The all-cooling operation mode is an operation mode in which all operating indoor units 103 perform cooling operation. The all-heating operation mode is an operation mode in which all operating indoor units 103 perform heating operation. The cooling-dominated operation mode is an operation mode in which both indoor units 103 performing cooling operation and indoor units 103 performing heating operation are present, with a high proportion of cooling operation. In other words, the cooling-dominated operation mode is an operation mode in which the indoor units 103 performing cooling operation and the indoor units 103 performing heating operation are mixed, and the cooling load is greater than the heating load. The heating-dominated operation mode is an operation mode in which the indoor units 103 performing cooling operation and the indoor units 103 performing heating operation are mixed, and the ratio of heating operation is high. In other words, the heating-dominated operation mode is an operation mode in which the indoor units 103 performing cooling operation and the indoor units 103 performing heating operation are mixed, and the heating load is greater than the cooling load.

[0017] [Configuration of outdoor unit 101] The outdoor unit 101 includes a compressor 1, a heat source-side flow switching device 2, a heat source-side heat exchanger 3, and a heat source-side throttle device 5. In the first embodiment, the outdoor unit 101 also includes an outdoor fan 4 and a control device 6. The compressor 1 compresses and discharges a refrigerant. Specifically, the compressor 1 draws in a low-temperature, low-pressure gas refrigerant, compresses it, and discharges the high-temperature, high-pressure gas refrigerant. The compressor 1 circulates the refrigerant in a refrigerant circuit. The compressor 1 is, for example, a capacity-controllable inverter-type compressor.

[0018] The heat source side heat exchanger 3 exchanges heat between the outdoor air and the refrigerant. One connection port of the heat source side heat exchanger 3 is connected to the heat source side flow switching device 2. The other connection port of the heat source side heat exchanger 3 is connected to the heat source side throttle device 5. Specifically, the heat source side heat exchanger 3 is, for example, a fin-tube type heat exchanger. The heat source side heat exchanger 3 exchanges heat between the refrigerant and the outdoor air supplied by the outdoor fan 4. The heat source side heat exchanger 3 functions as a condenser during cooling operation, condensing and liquefying the refrigerant. The heat source side heat exchanger 3 also functions as an evaporator during heating operation, evaporating and gasifying the refrigerant.

[0019] The outdoor fan 4 is, for example, a propeller fan. The outdoor fan 4 supplies outdoor air around the outdoor unit 101 to the heat source-side heat exchanger 3. The rotation speed of the outdoor fan 4 is controlled by the control device 6, thereby controlling the condensation capacity or evaporation capacity of the heat source-side heat exchanger 3.

[0020] The heat source-side throttling device 5 is connected to the heat source-side heat exchanger 3 and the first connecting pipe 7, and reduces the pressure of the refrigerant flowing between the heat source-side heat exchanger 3 and the first connecting pipe 7. The heat source-side throttling device 5 is, for example, an electronic expansion valve that can adjust the opening degree of the throttling. By adjusting the opening degree, the heat source-side throttling device 5 controls the pressure of the refrigerant flowing into the relay unit 102 in the cooling only operation mode and the cooling-dominated operation mode, and controls the pressure of the refrigerant flowing into the heat source-side heat exchanger 3 in the heating only operation mode and the heating-dominated operation mode.

[0021] The heat source-side flow switching device 2 switches the flow path of the refrigerant flowing through the outdoor unit 101 between a first heat source-side flow path 2a and a second heat source-side flow path 2b. The first heat source-side flow path 2a is a flow path through which the refrigerant flows from the outdoor unit 101 to a first connecting pipe 7. The second heat source-side flow path 2b is a flow path through which the refrigerant flows from the outdoor unit 101 to a second connecting pipe 8. Specifically, the heat source-side flow switching device 2 is, for example, a four-way valve. The heat source-side flow path switching device 2 switches the connection destination of the discharge port of the compressor 1 to one of the heat source-side heat exchanger 3 and the second connecting pipe 8 depending on the operation mode of the air conditioning apparatus 100. The heat source-side flow path switching device 2 also switches the connection destination of the suction port of the compressor 1 to the other of the heat source-side heat exchanger 3 and the second connecting pipe 8 depending on the operation mode of the air conditioning apparatus 100. As a result, the heat-source-side flow switching device 2 can switch the flow path of the refrigerant flowing through the outdoor unit 101 to the first heat-source-side flow path 2a or the second heat-source-side flow path 2b depending on the operation mode of the air conditioning apparatus 100. Here, as will be described later, the heat-source-side flow switching device 2 switches to the first heat-source-side flow path 2a in the cooling-only operation mode and the cooling-dominated operation mode, and switches to the second heat-source-side flow path 2b in the heating-only operation mode and the heating-dominated operation mode. The heat-source-side flow switching device 2 may be a combination of a three-way valve or a two-way valve.

[0022] The control device 6 controls the operation of the compressor 1, the heat-source-side flow switching device 2, the outdoor fan 4, and the heat-source-side throttle device 5. Specifically, the control device 6 controls the drive frequency of the compressor 1, the flow path of the heat-source-side flow switching device 2, the rotation speed of the outdoor fan 4, and the opening degree of the heat-source-side throttle device 5 based on the detection results of sensors installed in the outdoor unit 101. The sensors installed in the outdoor unit 101 include, for example, a discharge pressure sensor 50 that detects the pressure of the refrigerant discharged from the compressor 1, a discharge temperature sensor 51 that detects the temperature of the refrigerant discharged from the compressor 1, a heat-source-side heat exchanger temperature sensor 52 that detects the temperature of the refrigerant flowing out of the heat-source-side heat exchanger 3, and an outdoor air temperature sensor 53 that detects the outdoor air temperature. The temperature sensor is, for example, a thermistor. The control device 6 can perform data communication with the control device 19 installed in the relay unit 102. The control device 6 can also perform data communication with the control devices 13 installed in each indoor unit 103.

[0023] The control device 6 mounted on the outdoor unit 101, the control device 19 (described later) mounted on the relay unit 102, and the control device 13 (described later) mounted on the indoor unit 103 are configured, for example, as follows. The control devices 6, 19, and 13 are configured by dedicated hardware or a CPU (Central Processing Unit) that executes programs stored in memory. The CPU is also called a central processing unit, processing device, arithmetic unit, microprocessor, microcomputer, or processor.

[0024] When the control devices 6, 19, and 13 are dedicated hardware, the control devices 6, 19, and 13 may be, for example, a single circuit, a composite circuit, an ASIC (Application Specific Integrated Circuit), an FPGA (Field-Programmable Gate Array), or a combination thereof. Each of the functional units realized by the control devices 6, 19, and 13 may be realized by separate hardware, or each functional unit may be realized by a single piece of hardware.

[0025] When the control devices 6, 19, and 13 are CPUs, the functions executed by the control devices 6, 19, and 13 are realized by software, firmware, or a combination of software and firmware. The software and firmware are written as programs and stored in memory. The CPU realizes the functions of the control devices 6, 19, and 13 by reading and executing the programs stored in memory. Here, the memory is, for example, a non-volatile or volatile semiconductor memory such as a RAM, a ROM, a flash memory, an EPROM, or an EEPROM.

[0026] The control devices 6, 19, and 13 may be configured such that some of their functions are realized by dedicated hardware and some of their functions are realized by software or firmware.

[0027] [Configuration of indoor units 103] Each indoor unit 103 includes a load-side heat exchanger 10 and a load-side expansion device 11. In addition, in the first embodiment, each indoor unit 103 includes an indoor fan 12 and a control device 13. That is, the indoor unit 103a includes a load-side heat exchanger 10a, a load-side expansion device 11a, an indoor fan 12a, and a control device 13a. The indoor unit 103b includes a load-side heat exchanger 10b, a load-side expansion device 11b, an indoor fan 12b, and a control device 13b. The indoor unit 103c includes a load-side heat exchanger 10c, a load-side expansion device 11c, an indoor fan 12c, and a control device 13c. The indoor unit 103d includes a load-side heat exchanger 10d, a load-side expansion device 11d, an indoor fan 12d, and a control device 13d.

[0028] The load-side heat exchanger 10 exchanges heat between the load-side heat medium and the refrigerant. The load-side heat medium is a heat exchange target for the refrigerant flowing through the load-side heat exchanger 10. In the first embodiment, the load-side heat medium is indoor air. Specifically, the load-side heat exchanger 10 is, for example, a fin-tube heat exchanger. The load-side heat exchanger 10 exchanges heat with indoor air supplied by an indoor fan 12 to generate air-conditioned air or air for heating to be supplied to a space to be air-conditioned. The load-side heat exchanger 10 may also be a plate-type heat exchanger in which the refrigerant exchanges heat with water, antifreeze, or the like. That is, the load-side heat medium may be water, antifreeze, or the like.

[0029] The load-side expansion device 11 is connected to the load-side heat exchanger 10 and reduces the pressure of the refrigerant to adjust the amount of refrigerant flowing into the load-side heat exchanger 10. Specifically, the load-side expansion device 11 is, for example, an electronic expansion valve whose opening can be adjusted continuously or in multiple stages. The load-side expansion device 11 is connected in series with the load-side heat exchanger 10 and reduces the pressure of the refrigerant flowing into the load-side heat exchanger 10 to expand it. The load-side expansion device 11 is located upstream of the load-side heat exchanger 10 in the refrigerant flow in the cooling only operation mode.

[0030] The control device 13 controls the rotation speed of the indoor fan 12 and the opening degree of the load-side throttle device 11 .

[0031] [Configuration of Repeater 102] The repeater 102 includes a plurality of opening and closing devices 30 and a repeater flow path switching device 14. In the first embodiment, the repeater 102 also includes a gas-liquid separator 17, a repeater throttle device 18, and a control device 19.

[0032] The gas-liquid separator 17 separates the gas-liquid two-phase refrigerant that has flowed into the relay unit 102 from the first connecting pipe 7 into liquid refrigerant that is to flow into the load-side expansion device 11 of at least one of the indoor units 103, and gas refrigerant that is to flow into at least one of the opening and closing devices 30. In Embodiment 1, an inlet 17a for the gas-liquid two-phase refrigerant of the gas-liquid separator 17 is connected to the first connecting pipe 7. An outlet 17b for the gas refrigerant of the gas-liquid separator 17 is connected to a first flow path 14a (described later) of the relay flow path switching device 14. The outlet 17b for the gas refrigerant of the gas-liquid separator 17 is connected to each of the opening and closing devices 30 via the relay flow path switching device 14. An outlet 17c for the liquid refrigerant of the gas-liquid separator 17 is connected to the load-side expansion device 11 of each indoor unit 103.

[0033] Specifically, in the cooling-dominated operation mode, the gas-liquid separator 17 separates the high-pressure gas-liquid two-phase refrigerant generated in the outdoor unit 101 into liquid refrigerant and gas refrigerant. The gas-liquid separator 17 then discharges the separated liquid refrigerant from outlet 17c to supply cold heat to some of the indoor units 103. The gas-liquid separator 17 also discharges the separated gas refrigerant from outlet 17b to supply hot heat to some of the indoor units 103.

[0034] One opening and closing device 30 is provided for each indoor unit 103. That is, the air conditioning apparatus 100 according to the first embodiment includes an opening and closing device 30a connected to the indoor unit 103a, an opening and closing device 30b connected to the indoor unit 103b, an opening and closing device 30c connected to the indoor unit 103c, and an opening and closing device 30d connected to the indoor unit 103d. That is, each opening and closing device 30 is connected to a load-side heat exchanger 10 of one of the indoor units 103. In the first embodiment, specifically, the opening and closing device 30 is connected to a connection port of the load-side heat exchanger 10 opposite to the connection port to which the load-side throttle device 11 is connected. Each opening and closing device 30 has an outflow path and an inflow path. The outflow path is a path through which refrigerant flows from the relay unit 102 to the load-side heat exchanger 10. The inflow path is a path through which refrigerant flows from the load-side heat exchanger 10 to the relay unit 102. The opening and closing device 30 is configured to close the inflow passage when the outflow passage is open, and to open the inflow passage when the outflow passage is closed.

[0035] Specifically, in the first embodiment, each of the opening and closing devices 30 has the following configuration. Each of the opening and closing devices 30 includes a first opening and closing device 31 and a second opening and closing device 32 connected in parallel to the load side heat exchanger 10. That is, the opening and closing device 30a includes a first opening and closing device 31a and a second opening and closing device 32a connected in parallel to the load side heat exchanger 10a. The opening and closing device 30b includes a first opening and closing device 31b and a second opening and closing device 32b connected in parallel to the load side heat exchanger 10b. The opening and closing device 30c includes a first opening and closing device 31c and a second opening and closing device 32c connected in parallel to the load side heat exchanger 10c. The opening and closing device 30d includes a first opening and closing device 31d and a second opening and closing device 32d connected in parallel to the load side heat exchanger 10d.

[0036] The first opening and closing device 31 is configured to be able to freely open and close a flow path formed in the first opening and closing device 31. The flow path formed in the first opening and closing device 31 serves as an outflow flow path. For example, a high-temperature, high-pressure gas refrigerant to be supplied to the load-side heat exchanger 10 flows through the flow path formed in the first opening and closing device 31. The first opening and closing device 31 is configured, for example, with a solenoid valve. Note that the first opening and closing device 31 may be a throttle device with a full-closing function as long as it is able to open and close the flow path.

[0037] The second opening and closing device 32 is configured to be able to freely open and close the flow path formed in the second opening and closing device 32. The flow path formed in the second opening and closing device 32 serves as an inflow flow path. For example, a low-pressure, low-temperature gas refrigerant flowing out from the load-side heat exchanger 10 flows through the flow path formed in the second opening and closing device 32. The second opening and closing device 32 is configured, for example, by a solenoid valve. Note that the second opening and closing device 32 may be a throttling device with a full-closing function as long as it is able to open and close the flow path. Furthermore, the opening and closing device 30 is not limited to a configuration including the first opening and closing device 31 and the second opening and closing device 32. For example, the opening and closing device 30 may be configured by a three-way valve.

[0038] The relay flow path switching device 14 is connected to each of the first connection pipe 7, the second connection pipe 8, and the opening and closing device 30. In the first embodiment, the relay flow path switching device 14 is connected to the first connection pipe 7 via a gas-liquid separator 17. The relay flow path switching device 14 is configured to switch the flow path as follows when the flow path of the heat source-side flow path switching device 2 is switched. Specifically, there may be indoor units 103 whose operation mode is the same before and after the flow path switching of the heat source-side flow path switching device 2. For example, there may be indoor units 103 whose operation mode remains in the cooling operation mode before and after the flow path switching of the heat source-side flow path switching device 2. Furthermore, there may be indoor units 103 whose operation mode remains in the heating operation mode before and after the flow path switching of the heat source-side flow path switching device 2. The relay flow path switching device 14 is configured to keep the open / closed state of the opening and closing device 30 connected to the indoor units 103 whose operation mode is the same before and after the flow path switching of the heat source-side flow path switching device 2 the same before and after the flow path switching of the heat source-side flow path switching device 2.

[0039] In the first embodiment, the relay flow path switching device 14 is formed with a first flow path 14a that can be opened and closed, a second flow path 14b that can be opened and closed, a third flow path 14c that can be opened and closed, and a fourth flow path 14d that can be opened and closed. The first flow path 14a is a flow path that connects the first connection pipe 7 to each of the outflow flow paths of the opening and closing device 30. That is, the first flow path 14a is a flow path that connects the first connection pipe 7 to each of the first opening and closing devices 31. The second flow path 14b is a flow path that connects the second connection pipe 8 to each of the inflow flow paths of the opening and closing device 30. That is, the second flow path 14b is a flow path that connects the second connection pipe 8 to each of the second opening and closing devices 32. The third flow path 14c is a flow path that connects the second connection pipe 8 to each of the outflow flow paths of the opening and closing device 30. That is, the third flow path 14c is a flow path that connects the second connection pipe 8 to each of the first opening and closing devices 31. The fourth flow path 14d is a flow path that connects the first connection pipe 7 and each of the inlet flow paths of the opening and closing devices 30. That is, the fourth flow path 14d is a flow path that connects the first connection pipe 7 and each of the second opening and closing devices 32.

[0040] When the air conditioning apparatus 100 is operating in a cooling-only operation mode or a cooling-dominant operation mode, the heat-source-side flow path switching device 2 is configured as the first heat-source-side flow path 2a. When the heat-source-side flow path switching device 2 is configured as the first heat-source-side flow path 2a, the first flow path 14a and the second flow path 14b of the relay flow path switching device 14 are open, and the third flow path 14c and the fourth flow path 14d are closed. When the air conditioning apparatus 100 is operating in a heating-only operation mode or a heating-dominant operation mode, the heat-source-side flow path switching device 2 is configured as the second heat-source-side flow path 2b. When the heat-source-side flow path switching device 2 is configured as the second heat-source-side flow path 2b, the third flow path 14c and the fourth flow path 14d of the relay flow path switching device 14 are open, and the first flow path 14a and the second flow path 14b are closed. By switching between the first flow path 14a, the second flow path 14b, the third flow path 14c, and the fourth flow path 14d in this manner, the relay flow path switching device 14 can make the open / closed state of the opening / closing device 30 connected to the indoor unit 103, which has the same operating mode before and after switching the flow path of the heat source side flow path switching device 2, the same before and after switching the flow path of the heat source side flow path switching device 2.

[0041] The switching of the open / closed states of the first flow path 14a, the second flow path 14b, the third flow path 14c, and the fourth flow path 14d of the heat source side flow path switching device 2 is controlled by the control device 19. The control device 19 switches the open / closed states of the first flow path 14a, the second flow path 14b, the third flow path 14c, and the fourth flow path 14d, for example, at the same timing as the flow paths of the heat source side flow path switching device 2 are switched.

[0042] The repeater throttle device 18 is provided in the refrigerant piping connecting the gas-liquid separator 17 and the load-side throttle device 11. The repeater throttle device 18 functions as a pressure reducing valve and an on-off valve. The repeater throttle device 18 reduces the pressure of the liquid refrigerant to a predetermined pressure and opens and closes the flow path of the liquid refrigerant. The repeater throttle device 18 can variably adjust its opening, for example, continuously or in multiple stages. For example, an electronic expansion valve or the like is used as the repeater throttle device 18.

[0043] The control device 19 controls the relay flow path switching device 14. Specifically, the control device 19 controls the open / close state of each flow path of the relay flow path switching device 14. The control device 19 also controls the opening degree of the relay throttle device 18 and the open / close state of the opening / closing device 30. In other words, the control device 19 controls the open / close states of the first opening / closing device 31 and the second opening / closing device 32.

[0044] Next, we will explain each operation mode executed by the air conditioning apparatus 100. As mentioned above, the operation modes executed by the air conditioning apparatus 100 include the cooling only operation mode, the cooling-dominated operation mode, the heating only operation mode, and the heating-dominated operation mode. Each operation mode will be explained below.

[0045] [Cooling-only operation mode] The cooling-only operation mode executed by the air conditioning apparatus 100 will be described with reference to Fig. 1. In Fig. 1, the cooling-only operation mode will be described using an example in which all indoor units 103 are performing cooling operation. In other words, Fig. 1 illustrates an example in which a cooling load is generated in all of the load-side heat exchangers 10a to 10d.

[0046] In the cooling only operation mode, the control device 6 switches the flow path of the heat source-side flow path switching device 2 of the outdoor unit 101 to the first heat source-side flow path 2a. In other words, the control device 6 switches the flow path of the heat source-side flow path switching device 2 of the outdoor unit 101 to a flow path through which the refrigerant discharged from the compressor 1 flows into the heat source-side heat exchanger 3. The control device 19 also controls the relay flow path switching device 14 to open the first flow path 14a and the second flow path 14b and close the third flow path 14c and the fourth flow path 14d.

[0047] When the compressor 1 is driven, it compresses a low-temperature, low-pressure refrigerant and discharges it as a high-temperature, high-pressure gas refrigerant. The high-temperature, high-pressure gas refrigerant discharged from the compressor 1 flows into the heat-source-side heat exchanger 3 via the heat-source-side flow switching device 2. The high-temperature, high-pressure gas refrigerant that has flowed into the heat-source-side heat exchanger 3 then becomes a high-pressure liquid refrigerant while dissipating heat to the outdoor air. The high-pressure liquid refrigerant that has flowed out of the heat-source-side heat exchanger 3 flows out of the outdoor unit 101, passes through the first connecting pipe 7, and flows into the relay unit 102.

[0048] The high-pressure liquid refrigerant that flows into the relay unit 102 passes through the gas-liquid separator 17, the relay unit throttling device 18, and the connecting pipe 9b, and flows into each indoor unit 103. The high-pressure liquid refrigerant that flows into each indoor unit 103 is decompressed and expanded by the load-side throttling device 11, becoming a low-temperature, low-pressure, two-phase gas-liquid refrigerant. This two-phase gas-liquid refrigerant flows into the load-side heat exchanger 10, which functions as an evaporator, and absorbs heat from the indoor air, cooling the indoor air and becoming a low-temperature, low-pressure gas refrigerant.

[0049] In this case, the load-side throttle device 11 of each indoor unit 103 is controlled by the control device 13 as follows. Each indoor unit 103 is equipped with a first load-side temperature sensor 54 that detects the temperature of refrigerant flowing into the load-side heat exchanger 10 when the load-side heat exchanger 10 functions as an evaporator. The first load-side temperature sensor 54 detects the temperature of refrigerant flowing out of the load-side heat exchanger 10 when the load-side heat exchanger 10 functions as a condenser. Each indoor unit 103 is also equipped with a second load-side temperature sensor 55 that detects the temperature of refrigerant flowing out of the load-side heat exchanger 10 when the load-side heat exchanger 10 functions as an evaporator. The opening degree of the load-side throttle device 11 of each indoor unit 103 is controlled by the control device 13 so that the superheat, which is the difference between the temperatures detected by the first load-side temperature sensor 54 and the second load-side temperature sensor 55, is constant. Superheat is sometimes referred to as the degree of superheat.

[0050] The low-temperature, low-pressure gas refrigerant flowing out of the load-side heat exchanger 10 of each indoor unit 103 flows out of each indoor unit 103 and passes through the connecting pipe 9a to flow into the relay unit 102. In addition, the low-temperature, low-pressure gas refrigerant flowing into the relay unit 102 from each indoor unit 103 passes through the second opening and closing device 32 of the opening and closing device 30 and merges. This merged low-temperature, low-pressure gas refrigerant flows out of the relay unit 102 via the second flow path 14b of the relay flow path switching device 14 and flows again into the outdoor unit 101 through the second connecting pipe 8. The low-temperature, low-pressure gas refrigerant flowing into the outdoor unit 101 passes through the heat-source-side flow path switching device 2 and is sucked into the compressor 1 again.

[0051] [Cooling-dominated operation mode] Figure 2 is a refrigerant circuit diagram showing the flow of refrigerant in the cooling-dominated operation mode of the air conditioner according to embodiment 1. In Figure 2, the cooling-dominated operation mode will be described using as an example a case where the indoor units 103b, 103c, and 103d perform cooling operation and the indoor unit 103a performs heating operation. In other words, Figure 2 illustrates a case where a cooling load is generated in the load-side heat exchanger 10b, 10c, and 10d, and a heating load is generated in the load-side heat exchanger 10a.

[0052] In the cooling-dominated operation mode, the control device 6 switches the flow path of the heat-source-side flow path switching device 2 of the outdoor unit 101 to the first heat-source-side flow path 2a. In other words, the control device 6 switches the flow path of the heat-source-side flow path switching device 2 of the outdoor unit 101 to a flow path through which the refrigerant discharged from the compressor 1 flows into the heat-source-side heat exchanger 3. In addition, the control device 19 controls the relay flow path switching device 14 to open the first flow path 14a and the second flow path 14b and close the third flow path 14c and the fourth flow path 14d.

[0053] When the compressor 1 is driven, it compresses a low-temperature, low-pressure refrigerant and discharges it as a high-temperature, high-pressure gas refrigerant. The high-temperature, high-pressure gas refrigerant discharged from the compressor 1 flows into the heat-source-side heat exchanger 3 via the heat-source-side flow switching device 2. The high-temperature, high-pressure gas refrigerant that has flowed into the heat-source-side heat exchanger 3 then becomes a high-pressure two-phase gas-liquid refrigerant while dissipating heat to the outdoor air. The high-pressure two-phase gas-liquid refrigerant that has flowed out of the heat-source-side heat exchanger 3 flows out of the outdoor unit 101, passes through the first connecting piping 7, and flows into the relay unit 102.

[0054] The high-pressure gas-liquid two-phase refrigerant that flows into the relay unit 102 is separated into high-pressure gas refrigerant and high-pressure liquid refrigerant by the gas-liquid separator 17. This high-pressure gas refrigerant flows through the first flow path 14a of the relay flow path switching device 14, the first opening / closing device 31a, and the connecting pipe 9a, before flowing into the indoor unit 103a. The high-pressure gas refrigerant that flows into the indoor unit 103a then flows into the load-side heat exchanger 10a, which functions as a condenser, and dissipates heat into the indoor air, heating the indoor air and becoming high-pressure liquid refrigerant.

[0055] In this case, the load-side throttle device 11a of the indoor unit 103a is controlled by the control device 13a as follows. The relay unit 102 is equipped with an inlet-side pressure sensor 56 that detects the pressure of the liquid refrigerant flowing out of the gas-liquid separator 17 and flowing into the relay throttle device 18. Because the gas refrigerant flowing into the load-side heat exchanger 10a is the gas refrigerant flowing out of the gas-liquid separator 17, the pressure of the gas refrigerant is approximately the same as the pressure of the liquid refrigerant detected by the inlet-side pressure sensor 56. For this reason, the opening degree of the load-side throttle device 11a is controlled so that the subcooling level, which is the difference between the value obtained by converting the pressure detected by the inlet-side pressure sensor 56 into a saturation temperature and the temperature detected by the load-side first temperature sensor 54a, is constant. Note that subcooling level is sometimes referred to as the degree of supercooling.

[0056] The liquid refrigerant flowing out of the load-side heat exchanger 10a is decompressed and expanded in the load-side expansion device 11a and flows through the connecting pipe 9b into the relay unit 102. This refrigerant is merged with medium-pressure liquid refrigerant that has been separated in the gas-liquid separator 17 and expanded to medium pressure in the relay expansion device 18. At this time, the relay expansion device 18 is controlled by the control device 19 as follows. The relay unit 102 is equipped with an outlet pressure sensor 57 that detects the pressure of the refrigerant flowing out of the relay expansion device 18. The control device 19 controls the opening of the relay expansion device 18 so that the difference between the pressure detected by the inlet pressure sensor 56 and the pressure detected by the outlet pressure sensor 57 becomes a specified pressure difference. The specified pressure difference is, for example, 0.3 MPa.

[0057] The merged liquid refrigerant flows into the indoor units 103b, 103c, and 103d via the connecting pipe 9b. The refrigerant flowing into the indoor unit 103b is decompressed and expanded by the load-side throttle device 11b, becoming a low-temperature, low-pressure, two-phase gas-liquid refrigerant, which then flows into the load-side heat exchanger 10b, which functions as an evaporator. The low-temperature, low-pressure, two-phase gas-liquid refrigerant that flows into the load-side heat exchanger 10b absorbs heat from the indoor air, cooling it and becoming a low-temperature, low-pressure gas refrigerant. At this time, the opening degree of the load-side throttle device 11b is controlled by the control device 13b so that the superheat, which is obtained as the difference between the temperatures detected by the first load-side temperature sensor 54b and the second load-side temperature sensor 55b, remains constant.

[0058] Similarly, the refrigerant flowing into the indoor unit 103c is decompressed and expanded by the load-side throttle device 11c, becoming a low-temperature, low-pressure, two-phase gas-liquid refrigerant, which then flows into the load-side heat exchanger 10c, which functions as an evaporator. The low-temperature, low-pressure, two-phase gas-liquid refrigerant that has flowed into the load-side heat exchanger 10c absorbs heat from the indoor air, cooling it and becoming a low-temperature, low-pressure gas refrigerant. At this time, the opening degree of the load-side throttle device 11c is controlled by the control device 13c so that the superheat, which is obtained as the difference between the temperatures detected by the first load-side temperature sensor 54c and the second load-side temperature sensor 55c, is constant.

[0059] Similarly, the refrigerant flowing into the indoor unit 103d is decompressed and expanded by the load-side throttle device 11d, becoming a low-temperature, low-pressure, two-phase gas-liquid refrigerant, which then flows into the load-side heat exchanger 10d, which functions as an evaporator. The low-temperature, low-pressure, two-phase gas-liquid refrigerant that has flowed into the load-side heat exchanger 10d absorbs heat from the indoor air, cooling it and becoming a low-temperature, low-pressure gas refrigerant. At this time, the opening degree of the load-side throttle device 11d is controlled by the control device 13d so that the superheat, which is obtained as the difference between the temperatures detected by the first load-side temperature sensor 54d and the second load-side temperature sensor 55d, is constant.

[0060] The low-temperature, low-pressure gas refrigerant flowing out of the load-side heat exchanger 10b passes through the connecting pipe 9a and flows into the second opening and closing device 32b. The low-temperature, low-pressure gas refrigerant flowing out of the load-side heat exchanger 10c passes through the connecting pipe 9a and flows into the second opening and closing device 32c. The low-temperature, low-pressure gas refrigerant flowing out of the load-side heat exchanger 10d passes through the connecting pipe 9a and flows into the second opening and closing device 32d. The low-temperature, low-pressure gas refrigerant flowing out of the second opening and closing device 32b, the low-temperature, low-pressure gas refrigerant flowing out of the second opening and closing device 32c, and the low-temperature, low-pressure gas refrigerant flowing out of the second opening and closing device 32d join together and then flow out of the relay unit 102 via the second flow path 14b of the relay flow path switching device 14. The low-temperature, low-pressure gas refrigerant flowing out of the relay unit 102 passes through the second connecting pipe 8 and flows back into the outdoor unit 101. The refrigerant that has flowed into the outdoor unit 101 passes through the heat source side flow switching device 2 and is sucked into the compressor 1 again.

[0061] [Heating only operation mode] Fig. 3 is a refrigerant circuit diagram showing the flow of refrigerant in the heating only operation mode of the air conditioner according to Embodiment 1. In Fig. 3, the heating only operation mode will be explained using as an example a case where all indoor units 103 are performing heating operation. In other words, Fig. 3 illustrates a case where a heating load is generated in all of the load-side heat exchangers 10a to 10d.

[0062] In the heating only operation mode, the control device 6 switches the flow path of the heat source-side flow path switching device 2 of the outdoor unit 101 to the second heat source-side flow path 2b. In other words, the control device 6 switches the flow path of the heat source-side flow path switching device 2 of the outdoor unit 101 to a flow path through which the refrigerant discharged from the compressor 1 flows into the relay unit 102 without passing through the heat source-side heat exchanger 3. The control device 19 also controls the relay flow path switching device 14 to open the third flow path 14c and the fourth flow path 14d and close the first flow path 14a and the second flow path 14b.

[0063] When the compressor 1 is driven, the compressor 1 compresses a low-temperature, low-pressure refrigerant and discharges it as a high-temperature, high-pressure gas refrigerant. The high-temperature, high-pressure gas refrigerant discharged from the compressor 1 passes through the heat-source-side flow switching device 2 and flows out of the outdoor unit 101. The high-temperature, high-pressure gas refrigerant flowing out of the outdoor unit 101 flows through the second connecting pipe 8 into the relay unit 102.

[0064] The high-temperature, high-pressure gas refrigerant that flows into the relay unit 102 flows through the third flow path 14c of the relay flow path switching device 14, the first opening / closing device 31 connected to each indoor unit 103, and the connecting pipe 9a, before flowing into each indoor unit 103. The high-temperature, high-pressure gas refrigerant that flows into each indoor unit 103 flows into the load-side heat exchanger 10, which functions as a condenser. Here, the high-temperature, high-pressure gas refrigerant does not pass through a gas-liquid separator, thereby reducing pressure loss. The refrigerant that flows into the load-side heat exchanger 10 dissipates heat into the indoor air, heating it and becoming liquid refrigerant. The liquid refrigerant that flows out of the load-side heat exchanger 10 is decompressed and expanded by the load-side throttle device 11, becoming low-temperature, low-pressure, two-phase gas-liquid refrigerant, which then flows into the relay unit 102 through the connecting pipe 9b. At this time, the opening degree of the load side throttle device 11 is controlled by the control device 13 so that the subcooling obtained as the difference between the value obtained by converting the pressure detected by the discharge pressure sensor 50 into a saturation temperature and the temperature detected by the load side first temperature sensor 54 remains constant.

[0065] The low-temperature, low-pressure, two-phase gas-liquid refrigerant that flows from each indoor unit 103 into the relay unit 102 joins together, then flows through the bypass piping 20, the fourth flow path 14d of the relay flow path switching device 14, the gas-liquid separator 17, and the first connecting piping 7, before flowing into the outdoor unit 101. The low-temperature, low-pressure, two-phase gas-liquid refrigerant that flows into the outdoor unit 101 passes through the heat source-side throttle device 5, and then becomes low-temperature, low-pressure gas refrigerant while absorbing heat from the outdoor air in the heat source-side heat exchanger 3, and is then sucked into the compressor 1 again via the heat source-side flow path switching device 2.

[0066] [Heating-dominant operation mode] Fig. 4 is a refrigerant circuit diagram showing the flow of refrigerant in the heating-dominant operation mode of the air conditioner according to Embodiment 1. In Fig. 4, the heating-dominant operation mode will be described using an example in which the indoor units 103b, 103c, and 103d perform heating operation and the indoor unit 103a performs cooling operation. In other words, Fig. 4 illustrates a case in which a heating load is generated in the load-side heat exchanger 10b, 10c, and 10d, and a cooling load is generated in the load-side heat exchanger 10a.

[0067] In the heating-dominant operation mode, the control device 6 switches the flow path of the heat-source-side flow path switching device 2 of the outdoor unit 101 to the second heat-source-side flow path 2b. In other words, the control device 6 switches the flow path of the heat-source-side flow path switching device 2 of the outdoor unit 101 to a flow path through which the refrigerant discharged from the compressor 1 flows into the relay unit 102 without passing through the heat-source-side heat exchanger 3. In addition, the control device 19 controls the relay flow path switching device 14 to open the third flow path 14c and the fourth flow path 14d and close the first flow path 14a and the second flow path 14b.

[0068] When the compressor 1 is driven, the compressor 1 compresses a low-temperature, low-pressure refrigerant and discharges it as a high-temperature, high-pressure gas refrigerant. The high-temperature, high-pressure gas refrigerant discharged from the compressor 1 passes through the heat-source-side flow switching device 2 and flows out of the outdoor unit 101. The high-temperature, high-pressure gas refrigerant flowing out of the outdoor unit 101 flows through the second connecting pipe 8 into the relay unit 102.

[0069] The high-temperature, high-pressure gas refrigerant that flows into the relay unit 102 flows through the third flow path 14c of the relay flow path switching device 14 and into the first opening and closing device 31b, the first opening and closing device 31c, and the first opening and closing device 31b. The high-temperature, high-pressure gas refrigerant that flows into the first opening and closing device 31b flows through the connecting pipe 9a and into the indoor unit 103b. The high-temperature, high-pressure gas refrigerant that flows into the first opening and closing device 31c flows through the connecting pipe 9a and into the indoor unit 103c. The high-temperature, high-pressure gas refrigerant that flows into the first opening and closing device 31d flows through the connecting pipe 9a and into the indoor unit 103d. Here, the high-temperature, high-pressure gas refrigerant does not pass through the gas-liquid separator, thereby reducing pressure loss.

[0070] The high-temperature, high-pressure gas refrigerant that flows into the indoor unit 103b flows into the load-side heat exchanger 10b, which functions as a condenser. The high-temperature, high-pressure gas refrigerant that flows into the load-side heat exchanger 10b dissipates heat to the indoor air, heating it and becoming liquid refrigerant. The liquid refrigerant that flows out of the load-side heat exchanger 10b is depressurized and expanded by the load-side expansion device 11b and flows into the relay unit 102 via the connecting pipe 9b. Similarly, the high-temperature, high-pressure gas refrigerant that flows into the indoor unit 103c flows into the load-side heat exchanger 10c, which functions as a condenser. The high-temperature, high-pressure gas refrigerant that flows into the load-side heat exchanger 10c is depressurized and expanded by the load-side expansion device 11c and flows into the relay unit 102 via the connecting pipe 9b. Similarly, the high-temperature, high-pressure gas refrigerant that flows into the indoor unit 103d flows into the load-side heat exchanger 10d, which functions as a condenser. The high-temperature, high-pressure gas refrigerant that flows into the load-side heat exchanger 10d dissipates heat into the indoor air, heating the indoor air and becoming liquid refrigerant. The liquid refrigerant that flows out of the load-side heat exchanger 10d is decompressed and expanded by the load-side expansion device 11d, and flows into the relay unit 102 via the connecting pipe 9b.

[0071] The liquid refrigerant flowing into the relay unit 102 from the indoor unit 103b, the liquid refrigerant flowing into the relay unit 102 from the indoor unit 103c, and the liquid refrigerant flowing into the relay unit 102 from the indoor unit 103d are merged. Most of this merged liquid refrigerant flows into the bypass piping 20. The remaining portion of this merged liquid refrigerant flows into the indoor unit 103a through the connecting piping 9b. The liquid refrigerant flowing into the indoor unit 103a is decompressed and expanded by the load-side expansion device 11a, becoming a low-temperature, low-pressure, two-phase gas-liquid refrigerant that flows into the load-side heat exchanger 10a, which functions as an evaporator. The low-temperature, low-pressure, two-phase gas-liquid refrigerant that flows into the load-side heat exchanger 10a absorbs heat from the indoor air, cooling it and becoming a low-temperature, low-pressure gas refrigerant. The low-temperature, low-pressure gas refrigerant flowing out of the load-side heat exchanger 10a flows into the relay unit 102 via the connecting piping 9a and the second opening / closing device 32a. This low-temperature, low-pressure gas refrigerant merges with the refrigerant flowing out from the bypass piping 20 and becomes a two-phase gas-liquid refrigerant. This two-phase gas-liquid refrigerant flows through the fourth flow path 14d, the gas-liquid separator 17, and the first connecting piping 7, and flows into the outdoor unit 101. The refrigerant that flows into the outdoor unit 101 passes through the heat-source-side throttle device 5, and then becomes a low-temperature, low-pressure gas refrigerant while absorbing heat from the outdoor air in the heat-source-side heat exchanger 3, and is then sucked into the compressor 1 again via the heat-source-side flow switching device 2.

[0072] The air conditioner 100 according to the first embodiment is a two-pipe simultaneous cooling and heating air conditioner in which the outdoor unit 101 and the relay unit 102 are connected by two connecting pipes. In such a two-pipe simultaneous cooling and heating air conditioner, there may be indoor units whose operating mode remains the same before and after the refrigerant flow path in the outdoor unit is switched. Specifically, there may be indoor units whose operating mode remains the cooling mode or the heating mode before and after the refrigerant flow path in the outdoor unit is switched. When such indoor units exist, in a relay unit of a conventional two-pipe simultaneous cooling and heating air conditioner, when the refrigerant flow path in the outdoor unit is switched, it is necessary to change the open / close state of multiple opening / closing devices connected to the indoor units and maintain the refrigerant flow direction in the indoor units in order to keep the indoor units in the same operating mode. For this reason, conventional two-pipe simultaneous cooling and heating air conditioners may experience noise due to changes in refrigerant flow, a decrease in the air conditioning capacity of the indoor units due to fluctuations in refrigerant pressure, and a decrease in the performance of the air conditioner.

[0073] 1 and 4, in the air conditioning apparatus 100 according to the first embodiment, even if the refrigerant flow path in the outdoor unit 101 changes from that in FIG. 1 to that in FIG. 4, the open / closed state of the opening / closing device 30a connected to the indoor unit 103a whose operation mode does not change remains the same. In this way, in the air conditioning apparatus 100 according to the first embodiment, when the refrigerant flow path in the outdoor unit 101 is switched, the relay flow path switching device 14 can suppress changes in the open / closed state of the opening / closing device 30 connected to the indoor unit 103. Therefore, when the refrigerant flow path in the outdoor unit 101 is switched, the air conditioning apparatus 100 according to the first embodiment can suppress occurrences of abnormal noise due to a change in the refrigerant flow, a decrease in the air conditioning capacity of the indoor unit 103 due to refrigerant pressure fluctuations, a decrease in the performance of the air conditioning apparatus 100, and the like.

[0074] Here, a conventional two-pipe simultaneous cooling and heating air conditioner has been proposed that includes a refrigerant flow control unit between the outdoor unit and the relay unit to prevent changes in the open / close state of the switchgear connected to the indoor unit when the refrigerant flow path in the outdoor unit is switched. Specifically, the refrigerant flow control unit and the relay unit are connected by a high-pressure connection pipe through which a high-pressure refrigerant flows and a low-pressure connection pipe through which a low-pressure refrigerant flows. In a conventional two-pipe simultaneous cooling and heating air conditioner that prevents changes in the open / close state of the switchgear connected to the indoor unit, the refrigerant flows from the refrigerant flow control unit through the high-pressure connection pipe and from the relay unit through the low-pressure connection pipe, regardless of the refrigerant flow path in the outdoor unit. Such conventional two-pipe simultaneous cooling and heating air conditioners have the following problems.

[0075] In a conventional two-pipe simultaneous cooling and heating operation air conditioner without a refrigerant flow control unit, one of the two connecting pipes connecting the outdoor unit and the relay unit is configured to allow liquid refrigerant or two-phase gas-liquid refrigerant to flow, but not gas refrigerant. On the other hand, in a conventional two-pipe simultaneous cooling and heating operation air conditioner equipped with a refrigerant flow control unit, high-pressure gas refrigerant also flows through the high-pressure connecting pipe through which high-pressure liquid refrigerant flows. For this reason, the high-pressure connecting pipe used in a conventional two-pipe simultaneous cooling and heating operation air conditioner equipped with a refrigerant flow control unit has a larger diameter than the connecting pipe used in a conventional two-pipe simultaneous cooling and heating operation air conditioner without a refrigerant flow control unit. For this reason, a conventional two-pipe simultaneous cooling and heating operation air conditioner equipped with a refrigerant flow control unit requires a larger amount of refrigerant to be filled in the air conditioner compared to a conventional two-pipe simultaneous cooling and heating operation air conditioner without a refrigerant flow control unit. That is, in a conventional two-pipe simultaneous cooling and heating operation air conditioner that attempts to suppress changes in the open / close state of the opening / closing device connected to the indoor unit when the refrigerant flow path in the outdoor unit is switched, there is a problem that the amount of refrigerant sealed in increases. Furthermore, in such a conventional two-pipe simultaneous cooling and heating operation air conditioner, the inclusion of a refrigerant flow control unit can cause problems such as an increase in the installation space of the air conditioner, an increase in the manufacturing cost of the air conditioner, and an increase in the management cost of the air conditioner.

[0076] On the other hand, in the air conditioning apparatus 100 according to Embodiment 1, as described above, of the two connecting pipes connecting the outdoor unit 101 and the relay unit 102, the first connecting pipe 7, through which liquid refrigerant or gas-liquid two-phase refrigerant flows, is configured so that gas refrigerant does not flow. Therefore, the air conditioning apparatus 100 according to Embodiment 1 can prevent the diameter of the first connecting pipe 7 from increasing, and can also prevent an increase in the amount of refrigerant to be sealed. Furthermore, because the air conditioning apparatus 100 according to Embodiment 1 is provided with the relay flow path switching device 14 in the relay unit 102, it is possible to prevent the occurrence of problems such as an increase in the installation space for the air conditioning apparatus, an increase in the manufacturing cost of the air conditioning apparatus, and an increase in the management cost of the air conditioning apparatus.

[0077] As described above, the air conditioning apparatus 100 according to the first embodiment includes an outdoor unit 101, a relay unit 102 connected to the outdoor unit 101 by the first connecting pipe 7 and the second connecting pipe 8, and a plurality of indoor units 103 connected to the relay unit 102 by the connecting pipes 9a and 9b. The outdoor unit 101 includes a compressor 1 that compresses and discharges a refrigerant, a heat source-side heat exchanger 3 that exchanges heat between the refrigerant and outdoor air, a heat source-side throttle device 5 that is connected to the heat source-side heat exchanger 3 and the first connecting pipe 7 and reduces the pressure of the refrigerant flowing between the heat source-side heat exchanger 3 and the first connecting pipe 7, and a heat source-side flow switching device 2 that switches the flow path of the refrigerant flowing through the outdoor unit 101 between a first heat source-side flow path 2a through which the refrigerant flows into the first connecting pipe 7 or a second heat source-side flow path 2b through which the refrigerant flows into the second connecting pipe 8. Each of the indoor units 103 includes a load-side heat exchanger 10 that exchanges heat between a load-side heat medium and a refrigerant, and a load-side expansion device 11 that is connected to the load-side heat exchanger 10 and reduces the pressure of the refrigerant to adjust the amount of refrigerant flowing to the load-side heat exchanger. The relay unit 102 includes multiple opening / closing devices 30 and a relay flow path switching device 14. The opening / closing device 30 is connected to a connection port of one of the load-side heat exchangers 10 of the multiple indoor units 103 opposite to the connection port to which the load-side expansion device 11 is connected. Each of the opening / closing devices 30 has an outflow path through which refrigerant flows from the relay unit 102 to the load-side heat exchanger 10, and an inflow path through which refrigerant flows from the load-side heat exchanger 10 to the relay unit 102. Each of the opening / closing devices 30 closes the inflow path when the outflow path is open, and opens the inflow path when the outflow path is closed. The relay flow path switching device 14 is connected to each of the first connection pipe 7, the second connection pipe 8, and the opening and closing device 30. When the flow path of the heat source side flow path switching device 2 is switched, this relay flow path switching device 14 switches the flow path of the relay flow path switching device 14, and is configured to keep the open / closed state of the opening and closing device 30 connected to the indoor unit 103, which has the same operation mode before and after the switching of the flow path of the heat source side flow path switching device 2, the same before and after the switching of the flow path of the heat source side flow path switching device 2.

[0078] As described above, the air conditioning apparatus 100 configured in this manner can, when the refrigerant flow path in the outdoor unit 101 is switched, suppress changes in the open / closed state of the opening / closing device 30 connected to the indoor unit 103 by the relay flow path switching device 14. Furthermore, as described above, the air conditioning apparatus 100 configured in this manner can also suppress increases in the amount of refrigerant sealed inside.

[0079] Embodiment 2 A bypass pipe 21 and a bypass opening and closing device 22 shown in Embodiment 2 may be added to the configuration of the air conditioning apparatus 100 shown in Embodiment 1. Note that matters not specifically mentioned in Embodiment 2 are the same as in Embodiment 1. Furthermore, in Embodiment 2, components that perform the same functions as the components shown in Embodiment 1 will be assigned the same reference numerals as in Embodiment 1.

[0080] FIG. 5 is a refrigerant circuit diagram showing an example of the circuit configuration of an air conditioning apparatus according to Embodiment 2 in a cooling-only operation mode. FIG. 6 is a refrigerant circuit diagram showing an example of the circuit configuration of an air conditioning apparatus according to Embodiment 2 in a cooling-dominant operation mode. The air conditioning apparatus 100 according to Embodiment 2 includes a bypass piping 21 and a bypass opening / closing device 22 in addition to the configuration shown in Embodiment 1. The bypass piping 21 is a pipe that bypasses the second flow path 14b of the relay flow path switching device 14 and connects the second connection piping 8 to each of the inlet flow paths of the opening / closing device 30. In other words, the bypass piping 21 is a pipe that bypasses the second flow path 14b of the relay flow path switching device 14 and connects the second connection piping 8 to each of the second opening / closing devices 32 of the opening / closing device 30. The bypass opening / closing device 22 is provided in the bypass piping 21 and opens and closes the flow path of the bypass piping 21.

[0081] The opening and closing of this bypass opening and closing device 22 is controlled by a control device 19 provided in the relay unit 102. This bypass opening and closing device 22 is configured to be in an open state when the heat-source-side flow path switching device 2 is in the first heat-source-side flow path 2a. That is, the bypass opening and closing device 22 is in an open state when the air conditioning apparatus 100 is in a cooling-only operation mode or a cooling-dominant operation mode. In other words, the bypass opening and closing device 22 is in a closed state when the air conditioning apparatus 100 is in a heating-only operation mode or a heating-dominant operation mode. When the bypass opening and closing device 22 is in a closed state, the refrigerant flow in the air conditioning apparatus 100 according to Embodiment 2 is the same as in Embodiment 1. For this reason, the cooling-only operation mode and the cooling-dominant operation mode executed by the air conditioning apparatus 100 according to Embodiment 2 will be described below.

[0082] [Cooling Only Operation Mode] The cooling only operation mode executed by the air conditioning apparatus 100 will be described with reference to Fig. 5. In Fig. 5, the cooling only operation mode will be described using as an example a case where all indoor units 103 perform cooling operation.

[0083] In the cooling only operation mode, the control device 6 switches the flow path of the heat source side flow path switching device 2 of the outdoor unit 101 to the first heat source side flow path 2a. The control device 19 also controls the relay flow path switching device 14 to open the first flow path 14a and the second flow path 14b and close the third flow path 14c and the fourth flow path 14d. The control device 19 also opens the bypass opening and closing device 22.

[0084] When the compressor 1 is driven, it compresses a low-temperature, low-pressure refrigerant and discharges it as a high-temperature, high-pressure gas refrigerant. The high-temperature, high-pressure gas refrigerant discharged from the compressor 1 flows into the heat-source-side heat exchanger 3 via the heat-source-side flow switching device 2. The high-temperature, high-pressure gas refrigerant that has flowed into the heat-source-side heat exchanger 3 then becomes a high-pressure liquid refrigerant while dissipating heat to the outdoor air. The high-pressure liquid refrigerant that has flowed out of the heat-source-side heat exchanger 3 flows out of the outdoor unit 101, passes through the first connecting pipe 7, and flows into the relay unit 102.

[0085] The high-pressure liquid refrigerant that flows into the relay unit 102 passes through the gas-liquid separator 17, the relay unit throttling device 18, and the connecting pipe 9b, and flows into each indoor unit 103. The high-pressure liquid refrigerant that flows into each indoor unit 103 is decompressed and expanded by the load-side throttling device 11, becoming a low-temperature, low-pressure, two-phase gas-liquid refrigerant. This two-phase gas-liquid refrigerant flows into the load-side heat exchanger 10, which functions as an evaporator, and absorbs heat from the indoor air, cooling the indoor air and becoming a low-temperature, low-pressure gas refrigerant.

[0086] The low-temperature, low-pressure gas refrigerant flowing out from the load-side heat exchanger 10 of each indoor unit 103 flows out of each indoor unit 103 and passes through the connecting pipe 9a to flow into the relay unit 102. The low-temperature, low-pressure gas refrigerant flowing into the relay unit 102 from each indoor unit 103 passes through the second opening and closing device 32 of the opening and closing device 30 and merges. A portion of this merged low-temperature, low-pressure gas refrigerant flows into the second flow path 14b of the relay flow path switching device 14. The remaining portion of this merged low-temperature, low-pressure gas refrigerant passes through the bypass pipe 21 and merges with the low-temperature, low-pressure gas refrigerant flowing out from the second flow path 14b. The merged low-temperature, low-pressure gas refrigerant flows out of the relay unit 102 and passes through the second connecting pipe 8 to flow back into the outdoor unit 101. The low-temperature, low-pressure gas refrigerant flowing into the outdoor unit 101 passes through the heat-source-side flow path switching device 2 and is sucked back into the compressor 1. Here, by flowing a portion of the low-temperature, low-pressure gas refrigerant into the bypass pipe 21, it is possible to reduce pressure loss in the second flow path 14b of the relay flow path switching device 14. Therefore, the air conditioning apparatus 100 according to the second embodiment has improved performance in the cooling only operation mode compared to the air conditioning apparatus 100 shown in the first embodiment.

[0087] [Cooling-dominated operation mode] The cooling-dominated operation mode executed by the air conditioning apparatus 100 will be described with reference to Fig. 6. In Fig. 6, the cooling-dominated operation mode will be described using as an example a case where the indoor units 103b, 103c, and 103d perform cooling operation and the indoor unit 103a performs heating operation.

[0088] In the cooling-dominant operation mode, the control device 6 switches the flow path of the heat-source-side flow path switching device 2 of the outdoor unit 101 to the first heat-source-side flow path 2a. The control device 19 also controls the relay flow path switching device 14 to open the first flow path 14a and the second flow path 14b and close the third flow path 14c and the fourth flow path 14d. The control device 19 also opens the bypass opening and closing device 22.

[0089] When the compressor 1 is driven, it compresses a low-temperature, low-pressure refrigerant and discharges it as a high-temperature, high-pressure gas refrigerant. The high-temperature, high-pressure gas refrigerant discharged from the compressor 1 flows into the heat-source-side heat exchanger 3 via the heat-source-side flow switching device 2. The high-temperature, high-pressure gas refrigerant that has flowed into the heat-source-side heat exchanger 3 then becomes a high-pressure two-phase gas-liquid refrigerant while dissipating heat to the outdoor air. The high-pressure two-phase gas-liquid refrigerant that has flowed out of the heat-source-side heat exchanger 3 flows out of the outdoor unit 101, passes through the first connecting piping 7, and flows into the relay unit 102.

[0090] The high-pressure gas-liquid two-phase refrigerant that flows into the relay unit 102 is separated into high-pressure gas refrigerant and high-pressure liquid refrigerant by the gas-liquid separator 17. This high-pressure gas refrigerant flows through the first flow path 14a of the relay flow path switching device 14, the first opening / closing device 31a, and the connecting pipe 9a, before flowing into the indoor unit 103a. The high-pressure gas refrigerant that flows into the indoor unit 103a then flows into the load-side heat exchanger 10a, which functions as a condenser, and dissipates heat into the indoor air, heating the indoor air and becoming liquid refrigerant.

[0091] The liquid refrigerant flowing out of the load-side heat exchanger 10a is decompressed and expanded in the load-side expansion device 11a and passes through the connecting pipe 9b to flow into the relay unit 102. This refrigerant is separated in the gas-liquid separator 17 and then merges with medium-pressure liquid refrigerant that has been expanded to medium pressure in the relay expansion device 18. This merged liquid refrigerant flows through the connecting pipe 9b into the indoor units 103b, 103c, and 103d.

[0092] The refrigerant flowing into the indoor unit 103b is depressurized and expanded by the load-side expansion device 11b, becoming a two-phase gas-liquid refrigerant and flowing into the load-side heat exchanger 10b, which functions as an evaporator. The two-phase gas-liquid refrigerant flowing into the load-side heat exchanger 10b absorbs heat from the indoor air, cooling the indoor air and becoming a low-temperature, low-pressure gas refrigerant. Similarly, the refrigerant flowing into the indoor unit 103c is depressurized and expanded by the load-side expansion device 11c, becoming a two-phase gas-liquid refrigerant and flowing into the load-side heat exchanger 10c, which functions as an evaporator. The two-phase gas-liquid refrigerant flowing into the load-side heat exchanger 10c absorbs heat from the indoor air, cooling the indoor air and becoming a low-temperature, low-pressure gas refrigerant. Similarly, the refrigerant flowing into the indoor unit 103d is depressurized and expanded by the load-side expansion device 11d, becoming a two-phase gas-liquid refrigerant and flowing into the load-side heat exchanger 10d, which functions as an evaporator. The gas-liquid two-phase refrigerant that has flowed into the load-side heat exchanger 10d absorbs heat from the indoor air, thereby cooling the indoor air and becoming a low-temperature, low-pressure gas refrigerant.

[0093] The low-temperature, low-pressure gas refrigerant flowing out of the load-side heat exchanger 10b passes through the connecting pipe 9a and flows into the second opening and closing device 32b. The low-temperature, low-pressure gas refrigerant flowing out of the load-side heat exchanger 10c passes through the connecting pipe 9a and flows into the second opening and closing device 32c. The low-temperature, low-pressure gas refrigerant flowing out of the load-side heat exchanger 10d passes through the connecting pipe 9a and flows into the second opening and closing device 32d. The low-temperature, low-pressure gas refrigerant flowing out of the second opening and closing device 32b, the low-temperature, low-pressure gas refrigerant flowing out of the second opening and closing device 32c, and the low-temperature, low-pressure gas refrigerant flowing out of the second opening and closing device 32d are then merged. A portion of this merged low-temperature, low-pressure gas refrigerant flows into the second flow path 14b of the relay flow path switching device 14. The remaining portion of this merged low-temperature, low-pressure gas refrigerant passes through the bypass pipe 21 and merges with the low-temperature, low-pressure gas refrigerant flowing out of the second flow path 14b. Then, this joined low-temperature, low-pressure gas refrigerant flows out of the relay unit 102 and passes through the second connection pipe 8 before flowing back into the outdoor unit 101. The low-temperature, low-pressure gas refrigerant that has flowed into the outdoor unit 101 passes through the heat-source-side flow switching device 2 and is again drawn into the compressor 1. Here, by flowing a portion of the low-temperature, low-pressure gas refrigerant into the bypass pipe 21, it is possible to reduce pressure loss in the second flow path 14b of the relay flow switching device 14. Therefore, the air conditioning apparatus 100 according to the second embodiment has improved performance in the cooling-dominated operation mode compared to the air conditioning apparatus 100 shown in the first embodiment.

[0094] Embodiment 3 In the air conditioning apparatus 100 shown in Embodiment 1, the relay throttle device 18 was in a closed state when the heating only operation mode and the heating-dominated operation mode were executed. This is not a limitation, and as shown in Embodiment 3, the relay throttle device 18 may be in an open state in the heating only operation mode and the heating-dominated operation mode. Matters not specifically mentioned in Embodiment 3 are the same as in Embodiment 1 or Embodiment 2. Furthermore, in Embodiment 3, components that perform the same functions as the components shown in Embodiment 1 or Embodiment 2 are assigned the same reference numerals as in Embodiment 1 or Embodiment 2.

[0095] FIG. 7 is a refrigerant circuit diagram showing an example of the circuit configuration of an air conditioning apparatus according to Embodiment 3 in the full heating operation mode. FIG. 8 is a refrigerant circuit diagram showing an example of the circuit configuration of an air conditioning apparatus according to Embodiment 3 in the heating-dominated operation mode. In the air conditioning apparatus 100 according to Embodiment 3, the relay throttling device 18 is in an open state when the full heating operation mode and the heating-dominated operation mode are executed. That is, in the air conditioning apparatus 100 according to Embodiment 3, the relay throttling device 18 is configured to be in an open state when the heat-source-side flow path switching device 2 is in the second heat-source-side flow path 2b. The opening degree of the relay throttling device 18 at this time is not particularly limited. For example, the relay throttling device 18 may be fully open. Furthermore, for example, the opening degree of the relay throttling device 18 may be an intermediate opening degree between the fully closed state and the fully open state. Below, the operation of the air conditioning apparatus 100 according to Embodiment 3 when executing the full heating operation mode and the heating-dominated operation mode will be described.

[0096] [Heating only operation mode] The heating only operation mode executed by the air conditioning apparatus 100 will be described with reference to Fig. 7. In Fig. 7, the heating only operation mode will be described using as an example a case where all indoor units 103 perform heating operation.

[0097] In the heating only operation mode, the control device 6 switches the flow path of the heat source side flow path switching device 2 of the outdoor unit 101 to the second heat source side flow path 2b. The control device 19 also controls the relay flow path switching device 14 to open the third flow path 14c and the fourth flow path 14d and close the first flow path 14a and the second flow path 14b. The control device 19 also opens the relay unit throttle device 18.

[0098] When the compressor 1 is driven, the compressor 1 compresses a low-temperature, low-pressure refrigerant and discharges it as a high-temperature, high-pressure gas refrigerant. The high-temperature, high-pressure gas refrigerant discharged from the compressor 1 passes through the heat-source-side flow switching device 2 and flows out of the outdoor unit 101. The high-temperature, high-pressure gas refrigerant flowing out of the outdoor unit 101 flows through the second connecting pipe 8 into the relay unit 102.

[0099] The high-temperature, high-pressure gas refrigerant that flows into the relay unit 102 passes through the third flow path 14c of the relay flow path switching device 14, the first opening and closing device 31 connected to each indoor unit 103, and the connecting pipe 9a, and then flows into each indoor unit 103. The high-temperature, high-pressure gas refrigerant that flows into each indoor unit 103 flows into the load-side heat exchanger 10, which functions as a condenser. The refrigerant that flows into the load-side heat exchanger 10 dissipates heat to the indoor air, heating the indoor air and becoming liquid refrigerant. The liquid refrigerant that flows out of the load-side heat exchanger 10 is decompressed and expanded by the load-side expansion device 11, becoming low-temperature, low-pressure two-phase gas-liquid refrigerant and flows into the relay unit 102 through the connecting pipe 9b.

[0100] The low-temperature, low-pressure two-phase gas-liquid refrigerant that flows from each indoor unit 103 to the relay unit 102 merges and then flows into the bypass piping 20. Here, as described below, the low-temperature, low-pressure two-phase gas-liquid refrigerant that flows out of the bypass piping 20 passes through the gas-liquid separator 17 and then flows into the outdoor unit 101. When the low-temperature, low-pressure two-phase gas-liquid refrigerant passes through this gas-liquid separator 17, refrigeration oil that flows out from the compressor 1 accumulates in the gas-liquid separator 17. At this time, in the air conditioning apparatus 100 according to the third embodiment, the relay unit throttling device 18 is in the open state, so refrigeration oil flows out from the gas-liquid separator 17 and merges with the low-temperature, low-pressure two-phase gas-liquid refrigerant that flows into the bypass piping 20. Therefore, the air conditioning apparatus 100 according to the third embodiment can prevent refrigeration oil from accumulating in the gas-liquid separator 17.

[0101] The low-temperature, low-pressure, two-phase gas-liquid refrigerant that has flowed into the bypass piping 20 passes through the fourth flow path 14d of the relay flow path switching device 14, the gas-liquid separator 17, and the first connecting piping 7, and then flows into the outdoor unit 101. The low-temperature, low-pressure, two-phase gas-liquid refrigerant that has flowed into the outdoor unit 101 passes through the heat-source-side throttle device 5, and then becomes low-temperature, low-pressure gas refrigerant while absorbing heat from the outdoor air in the heat-source-side heat exchanger 3, and is then sucked into the compressor 1 again via the heat-source-side flow path switching device 2.

[0102] [Heating-dominated operation mode] The heating-dominated operation mode executed by the air conditioning apparatus 100 will be described with reference to Fig. 8. In Fig. 8, the heating-dominated operation mode will be described using as an example a case where the indoor units 103b, 103c, and 103d perform heating operation and the indoor unit 103a performs cooling operation.

[0103] In the heating-dominant operation mode, the control device 6 switches the flow path of the heat-source-side flow path switching device 2 of the outdoor unit 101 to the second heat-source-side flow path 2b. The control device 19 also controls the relay flow path switching device 14 to open the third flow path 14c and the fourth flow path 14d and close the first flow path 14a and the second flow path 14b. The control device 19 also opens the relay throttle device 18.

[0104] When the compressor 1 is driven, the compressor 1 compresses a low-temperature, low-pressure refrigerant and discharges it as a high-temperature, high-pressure gas refrigerant. The high-temperature, high-pressure gas refrigerant discharged from the compressor 1 passes through the heat-source-side flow switching device 2 and flows out of the outdoor unit 101. The high-temperature, high-pressure gas refrigerant flowing out of the outdoor unit 101 flows through the second connecting pipe 8 into the relay unit 102.

[0105] The high-temperature, high-pressure gas refrigerant that flows into the relay unit 102 flows through the third flow path 14c of the relay flow path switching device 14 and into the first opening and closing device 31b, the first opening and closing device 31c, and the first opening and closing device 31b. The high-temperature, high-pressure gas refrigerant that flows into the first opening and closing device 31b flows through the connecting pipe 9a and into the indoor unit 103b. The high-temperature, high-pressure gas refrigerant that flows into the first opening and closing device 31c flows through the connecting pipe 9a and into the indoor unit 103c. The high-temperature, high-pressure gas refrigerant that flows into the first opening and closing device 31d flows through the connecting pipe 9a and into the indoor unit 103d.

[0106] The high-temperature, high-pressure gas refrigerant that flows into the indoor unit 103b flows into the load-side heat exchanger 10b, which functions as a condenser. The high-temperature, high-pressure gas refrigerant that flows into the load-side heat exchanger 10b dissipates heat to the indoor air, heating it and becoming liquid refrigerant. The liquid refrigerant that flows out of the load-side heat exchanger 10b is depressurized and expanded by the load-side expansion device 11b and flows into the relay unit 102 via the connecting pipe 9b. Similarly, the high-temperature, high-pressure gas refrigerant that flows into the indoor unit 103c flows into the load-side heat exchanger 10c, which functions as a condenser. The high-temperature, high-pressure gas refrigerant that flows into the load-side heat exchanger 10c is depressurized and expanded by the load-side expansion device 11c and flows into the relay unit 102 via the connecting pipe 9b. Similarly, the high-temperature, high-pressure gas refrigerant that flows into the indoor unit 103d flows into the load-side heat exchanger 10d, which functions as a condenser. The high-temperature, high-pressure gas refrigerant that flows into the load-side heat exchanger 10d dissipates heat into the indoor air, heating the indoor air and becoming liquid refrigerant. The liquid refrigerant that flows out of the load-side heat exchanger 10d is decompressed and expanded by the load-side expansion device 11d, and flows into the relay unit 102 via the connecting pipe 9b.

[0107] The liquid refrigerant flowing into the relay unit 102 from the indoor unit 103b, the liquid refrigerant flowing into the relay unit 102 from the indoor unit 103c, and the liquid refrigerant flowing into the relay unit 102 from the indoor unit 103d are merged. Most of this merged liquid refrigerant flows into the bypass piping 20. The remaining portion of this merged liquid refrigerant flows through the connection piping 9b and into the indoor unit 103a. Here, in the air conditioning apparatus 100 according to Embodiment 3, the relay throttling device 18 is in the open state, so refrigerating machine oil flows out of the gas-liquid separator 17 and merges with the liquid refrigerant flowing into the bypass piping 20. Therefore, the air conditioning apparatus 100 according to Embodiment 3 can prevent refrigerating machine oil from accumulating in the gas-liquid separator 17.

[0108] The liquid refrigerant that flows into the indoor unit 103a is decompressed and expanded by the load-side throttle device 11a, becoming a low-temperature, low-pressure, two-phase gas-liquid refrigerant, which then flows into the load-side heat exchanger 10a, which functions as an evaporator. The low-temperature, low-pressure, two-phase gas-liquid refrigerant that flows into the load-side heat exchanger 10a absorbs heat from the indoor air, cooling the indoor air and becoming a low-temperature, low-pressure gas refrigerant. The low-temperature, low-pressure gas refrigerant that flows out of the load-side heat exchanger 10a flows into the relay unit 102 via the connecting pipe 9a and the second opening / closing device 32a. This low-temperature, low-pressure gas refrigerant merges with the refrigerant that flows out of the bypass pipe 20 and becomes a two-phase gas-liquid refrigerant. This two-phase gas-liquid refrigerant flows through the fourth flow path 14d, the gas-liquid separator 17, and the first connecting pipe 7, and flows into the outdoor unit 101. The refrigerant that flows into the outdoor unit 101 passes through the heat source side throttling device 5, and then absorbs heat from the outdoor air in the heat source side heat exchanger 3, becoming a low-temperature, low-pressure gas refrigerant, and is then sucked back into the compressor 1 via the heat source side flow switching device 2.

[0109] Embodiment 4 The position of the gas-liquid separator 17 within the relay unit 102 is not limited to the position shown in Embodiments 1 to 3. The gas-liquid separator 17 may be disposed within the relay unit 102 at the position shown in Embodiment 4, for example. Note that matters not specifically mentioned in Embodiment 4 are the same as in any of Embodiments 1 to 3. Furthermore, in Embodiment 4, components that perform the same functions as the components shown in any of Embodiments 1 to 3 are assigned the same reference numerals as in any of Embodiments 1 to 3.

[0110] FIG. 9 is a refrigerant circuit diagram showing an example of a circuit configuration of an air conditioner according to Embodiment 4 in a heating-only operation mode. FIG. 10 is a refrigerant circuit diagram showing an example of a circuit configuration of an air conditioner according to Embodiment 4 in a heating-dominated operation mode. In the relay flow path switching device 14 according to Embodiment 4, the first flow path 14a is connected to the first connection pipe 7 and the inlet 17a of the gas-liquid two-phase refrigerant of the gas-liquid separator 17. In the relay flow path switching device 14 according to Embodiment 4, the third flow path 14c is connected to the second connection pipe 8 and the inlet 17a of the gas-liquid two-phase refrigerant of the gas-liquid separator 17. The gas refrigerant outlet 17b of the gas-liquid separator 17 is directly connected to the outlet flow path of the opening and closing device 30. That is, the gas refrigerant outlet 17b of the gas-liquid separator 17 is directly connected to the first opening and closing device 31 of the opening and closing device 30. The operation of the air conditioner 100 according to Embodiment 4 when executing the heating-only operation mode and the heating-dominated operation mode will be described below.

[0111] [Heating only operation mode] The heating only operation mode executed by the air conditioning apparatus 100 will be described with reference to Fig. 9. In Fig. 9, the heating only operation mode will be described using as an example a case where all indoor units 103 perform heating operation.

[0112] In the heating only operation mode, the control device 6 switches the flow path of the heat source side flow path switching device 2 of the outdoor unit 101 to the second heat source side flow path 2b. In addition, the control device 19 controls the relay flow path switching device 14 to open the third flow path 14c and the fourth flow path 14d and close the first flow path 14a and the second flow path 14b.

[0113] When the compressor 1 is driven, the compressor 1 compresses a low-temperature, low-pressure refrigerant and discharges it as a high-temperature, high-pressure gas refrigerant. The high-temperature, high-pressure gas refrigerant discharged from the compressor 1 passes through the heat-source-side flow switching device 2 and flows out of the outdoor unit 101. The high-temperature, high-pressure gas refrigerant flowing out of the outdoor unit 101 flows through the second connecting pipe 8 into the relay unit 102.

[0114] The high-temperature, high-pressure gas refrigerant that flows into the relay unit 102 passes through the third flow path 14c of the relay flow path switching device 14, the gas-liquid separator 17, the first opening and closing device 31 connected to each indoor unit 103, and the connecting pipe 9a, before flowing into each indoor unit 103. The high-temperature, high-pressure gas refrigerant that flows into each indoor unit 103 flows into the load-side heat exchanger 10, which functions as a condenser. The refrigerant that flows into the load-side heat exchanger 10 dissipates heat into the indoor air, heating the indoor air and becoming liquid refrigerant. The liquid refrigerant that flows out of the load-side heat exchanger 10 is decompressed and expanded by the load-side throttle device 11, becoming low-temperature, low-pressure two-phase gas-liquid refrigerant and flows into the relay unit 102 through the connecting pipe 9b.

[0115] The low-temperature, low-pressure, two-phase gas-liquid refrigerant that flows from each indoor unit 103 into the relay unit 102 joins together and then flows into the bypass piping 20. The low-temperature, low-pressure, two-phase gas-liquid refrigerant that flows into the bypass piping 20 flows into the outdoor unit 101 via the fourth flow path 14d of the relay flow path switching device 14 and the first connection piping 7. In this way, by arranging the gas-liquid separator 17 at the position of the fourth embodiment, the low-temperature, low-pressure, two-phase gas-liquid refrigerant that flows out of the relay flow path switching device 14 can flow into the outdoor unit 101 without passing through the gas-liquid separator 17. Therefore, the air conditioning apparatus 100 according to the fourth embodiment can prevent refrigeration oil from accumulating in the gas-liquid separator 17.

[0116] The low-temperature, low-pressure gas-liquid two-phase refrigerant that flows into the outdoor unit 101 passes through the heat source side throttling device 5, and then becomes a low-temperature, low-pressure gas refrigerant while absorbing heat from the outdoor air in the heat source side heat exchanger 3, and is then sucked back into the compressor 1 via the heat source side flow switching device 2.

[0117] [Heating-dominated operation mode] The heating-dominated operation mode executed by the air conditioning apparatus 100 will be described with reference to Fig. 10. In Fig. 10, the heating-dominated operation mode will be described using as an example a case where the indoor units 103b, 103c, and 103d perform heating operation and the indoor unit 103a performs cooling operation.

[0118] In the heating-dominant operation mode, the control device 6 switches the flow path of the heat-source-side flow path switching device 2 of the outdoor unit 101 to the second heat-source-side flow path 2b. In addition, the control device 19 controls the relay flow path switching device 14 to open the third flow path 14c and the fourth flow path 14d and close the first flow path 14a and the second flow path 14b.

[0119] When the compressor 1 is driven, the compressor 1 compresses a low-temperature, low-pressure refrigerant and discharges it as a high-temperature, high-pressure gas refrigerant. The high-temperature, high-pressure gas refrigerant discharged from the compressor 1 passes through the heat-source-side flow switching device 2 and flows out of the outdoor unit 101. The high-temperature, high-pressure gas refrigerant flowing out of the outdoor unit 101 flows through the second connecting pipe 8 into the relay unit 102.

[0120] The high-temperature, high-pressure gas refrigerant that flows into the relay unit 102 flows through the third flow path 14c of the relay flow path switching device 14 and the gas-liquid separator 17, and then flows into the first opening and closing device 31b, the first opening and closing device 31c, and the first opening and closing device 31b. The high-temperature, high-pressure gas refrigerant that flows into the first opening and closing device 31b flows through the connecting pipe 9a and into the indoor unit 103b. The high-temperature, high-pressure gas refrigerant that flows into the first opening and closing device 31c flows through the connecting pipe 9a and into the indoor unit 103c. The high-temperature, high-pressure gas refrigerant that flows into the first opening and closing device 31d flows through the connecting pipe 9a and into the indoor unit 103d.

[0121] The high-temperature, high-pressure gas refrigerant that flows into the indoor unit 103b flows into the load-side heat exchanger 10b, which functions as a condenser. The high-temperature, high-pressure gas refrigerant that flows into the load-side heat exchanger 10b dissipates heat to the indoor air, heating it and becoming liquid refrigerant. The liquid refrigerant that flows out of the load-side heat exchanger 10b is depressurized and expanded by the load-side expansion device 11b and flows into the relay unit 102 via the connecting pipe 9b. Similarly, the high-temperature, high-pressure gas refrigerant that flows into the indoor unit 103c flows into the load-side heat exchanger 10c, which functions as a condenser. The high-temperature, high-pressure gas refrigerant that flows into the load-side heat exchanger 10c is depressurized and expanded by the load-side expansion device 11c and flows into the relay unit 102 via the connecting pipe 9b. Similarly, the high-temperature, high-pressure gas refrigerant that flows into the indoor unit 103d flows into the load-side heat exchanger 10d, which functions as a condenser. The high-temperature, high-pressure gas refrigerant that flows into the load-side heat exchanger 10d dissipates heat into the indoor air, heating the indoor air and becoming liquid refrigerant. The liquid refrigerant that flows out of the load-side heat exchanger 10d is decompressed and expanded by the load-side expansion device 11d, and flows into the relay unit 102 via the connecting pipe 9b.

[0122] The liquid refrigerant flowing into the relay unit 102 from the indoor unit 103b, the liquid refrigerant flowing into the relay unit 102 from the indoor unit 103c, and the liquid refrigerant flowing into the relay unit 102 from the indoor unit 103d are merged. Most of this merged liquid refrigerant flows into the bypass piping 20. The remaining portion of this merged liquid refrigerant flows into the indoor unit 103a through the connecting piping 9b. The liquid refrigerant flowing into the indoor unit 103a is decompressed and expanded by the load-side expansion device 11a, becoming a low-temperature, low-pressure, two-phase gas-liquid refrigerant that flows into the load-side heat exchanger 10a, which functions as an evaporator. The low-temperature, low-pressure, two-phase gas-liquid refrigerant that flows into the load-side heat exchanger 10a absorbs heat from the indoor air, cooling it and becoming a low-temperature, low-pressure gas refrigerant. The low-temperature, low-pressure gas refrigerant flowing out of the load-side heat exchanger 10a flows into the relay unit 102 via the connecting piping 9a and the second opening / closing device 32a. This low-temperature, low-pressure gas refrigerant merges with the refrigerant flowing out from the bypass piping 20 to form a two-phase gas-liquid refrigerant. This two-phase gas-liquid refrigerant flows into the outdoor unit 101 through the fourth flow path 14d and the first connecting piping 7. By arranging the gas-liquid separator 17 at the position of the fourth embodiment in this way, the two-phase gas-liquid refrigerant flowing out from the relay flow path switching device 14 can flow into the outdoor unit 101 without passing through the gas-liquid separator 17. Therefore, the air conditioning apparatus 100 according to the fourth embodiment can prevent refrigeration oil from accumulating in the gas-liquid separator 17.

[0123] The refrigerant that flows into the outdoor unit 101 passes through the heat source side throttling device 5, and then absorbs heat from the outdoor air in the heat source side heat exchanger 3, becoming a low-temperature, low-pressure gas refrigerant, and is then sucked back into the compressor 1 via the heat source side flow switching device 2.

[0124] 1 Compressor, 2 Heat source side flow path switching device, 2a First heat source side flow path, 2b Second heat source side flow path, 3 Heat source side heat exchanger, 4 Outdoor fan, 5 Heat source side throttle device, 6 Control device, 7 First connecting pipe, 8 Second connecting pipe, 9a Connecting pipe, 9b Connecting pipe, 10 (10a to 10d) Load side heat exchanger, 11 (11a to 11d) Load side throttle device, 12 (12a to 12d) Indoor fan, 13 (13a to 13d) Control device, 14 Relay flow path switching device, 14a First flow path, 14b Second flow path, 14c Third flow path, 14d Fourth flow path, 17 Gas-liquid separator, 17a Inlet, 17b Outlet, 17c Outlet, 18 Relay throttle device, 19 Control device, 20 Bypass pipe, 21 Bypass pipe, 22 Bypass opening / closing device, 30 (30a to 30d) opening / closing device, 31 (31a to 31d) first opening / closing device, 32 (32a to 32d) second opening / closing device, 50 discharge pressure sensor, 51 discharge temperature sensor, 52 heat source side heat exchanger temperature sensor, 53 outdoor air temperature sensor, 54 (54a to 54d) load side first temperature sensor, 55 (55a to 55d) load side second temperature sensor, 56 inlet side pressure sensor, 57 outlet side pressure sensor, 100 air conditioning device, 101 outdoor unit, 102 relay unit, 103 (103a to 103d) indoor unit.

Claims

1. The outdoor unit, a relay unit connected to the outdoor unit by a first connection pipe and a second connection pipe; A plurality of indoor units connected to the relay unit by connection pipes; Equipped with The outdoor unit is A compressor that compresses and discharges a refrigerant; a heat source side heat exchanger that exchanges heat between outdoor air and a refrigerant; a heat source side throttle device connected to the heat source side heat exchanger and the first connecting pipe and configured to reduce the pressure of a refrigerant flowing between the heat source side heat exchanger and the first connecting pipe; a heat source side flow path switching device for switching a flow path of the refrigerant flowing through the outdoor unit between a first heat source side flow path through which the refrigerant flows out to the first connecting pipe and a second heat source side flow path through which the refrigerant flows out to the second connecting pipe; Equipped with Each of the indoor units is a load-side heat exchanger for exchanging heat between a load-side heat medium and a refrigerant; a load-side throttle device connected to the load-side heat exchanger and reducing the pressure of the refrigerant to adjust the amount of refrigerant flowing through the load-side heat exchanger; Equipped with The repeater is a plurality of opening and closing devices connected to a connection port on the opposite side to a connection port to which the load side throttling device is connected in the load side heat exchanger of any of the plurality of indoor units, each of which has an outflow passage through which a refrigerant flows from the relay unit to the load side heat exchanger and an inflow passage through which a refrigerant flows from the load side heat exchanger to the relay unit, each of which closes the inflow passage when the outflow passage is open and opens the inflow passage when the outflow passage is closed; a relay flow path switching device connected to each of the first connection pipe, the second connection pipe, and the opening and closing device; Equipped with The relay flow path switching device is When the flow path of the heat source side flow path switching device is switched, the flow path of the relay flow path switching device is switched, and the open / closed state of the opening and closing device connected to the indoor unit having the same operation mode before and after the flow path switching of the heat source side flow path switching device is made the same before and after the flow path switching of the heat source side flow path switching device. Air conditioning equipment.

2. The relay flow path switching device is formed with a first flow path that can be opened and closed, a second flow path that can be opened and closed, a third flow path that can be opened and closed, and a fourth flow path that can be opened and closed, The first flow path is a flow path in which the first connection pipe and each of the outflow flow paths are connected, The second flow path is a flow path in which the second connection pipe and each of the inlet flow paths are connected, The third flow path is a flow path in which the second connection pipe and each of the outflow flow paths are connected, The fourth flow path is a flow path in which the first connection pipe and each of the inlet flow paths are connected. The air conditioning apparatus according to claim 1.

3. A control device for controlling the relay flow path switching device, The control device includes: When the heat source side flow path switching device is in the first heat source side flow path, the first flow path and the second flow path are in an open state, and the third flow path and the fourth flow path are in a closed state, When the heat source side flow path switching device is in the second heat source side flow path, the third flow path and the fourth flow path are in an open state, and the first flow path and the second flow path are in a closed state. The air conditioning apparatus according to claim 2.

4. a bypass pipe that bypasses the second flow path and connects the second connection pipe to each of the inlet flow paths; a bypass opening and closing device provided in the bypass piping and configured to open and close a flow path of the bypass piping; Equipped with When the heat source side flow path switching device is in the first heat source side flow path, the bypass opening and closing device is in an open state. The air conditioning apparatus according to claim 2 or 3.

5. The repeater is A gas-liquid separator that separates the gas-liquid two-phase refrigerant flowing in from the first connection pipe into a liquid refrigerant to be flowed into the load side throttling device of at least one of the indoor units and a gas refrigerant to be flowed into at least one of the opening and closing devices; a relay throttle device provided in a refrigerant pipe connecting the gas-liquid separator and each of the load side throttle devices; Equipped with The relay throttle device is configured to be in an open state when the heat source side flow path switching device is in the second heat source side flow path. The air conditioner according to any one of claims 1 to 3.

6. The relay unit includes a gas-liquid separator that separates the gas-liquid two-phase refrigerant flowing in from the first connection pipe into a liquid refrigerant to be flowed into the load side throttling device of at least one of the indoor units and a gas refrigerant to be flowed into at least one of the opening and closing devices; The relay flow path switching device is The first flow path is connected to the first connection pipe and an inlet of the gas-liquid two-phase refrigerant of the gas-liquid separator, The third flow path is connected to the second connection pipe and the inlet for the gas-liquid two-phase refrigerant of the gas-liquid separator. The air conditioning apparatus according to claim 2 or 3.