WO2023139703A1 - Air conditioning device - Google Patents

Abstract

This air conditioning device comprises: a heat source machine having a compressor, a flow path switching valve, and a heat source-side heat exchanger; an indoor unit that has a load-side flow rate adjustment valve and a load-side heat exchanger, and performs a cooling operation or a heating operation; a relay that is connected to the heat source machine by a low-pressure tube and a high-pressure tube, is connected to the indoor unit by a gas branch tube and a liquid branch tube, and supplies, to the indoor unit, a refrigerant supplied from the heat source machine; and a control device, wherein the relay comprises a branch part that allows communication between the gas branch tube and the low-pressure tube when the indoor unit performs the cooling operation, and allows communication between the gas branch tube and the high-pressure tube when the indoor unit performs the heating operation, the branch part has an expansion valve which is connected to the gas branch tube and the low-pressure tube and of which the opening degree is adjustable, and the control device controls the expansion valve such that communication is allowed between the gas branch tube and the low-pressure tube when the heat source machine is stopped.

Description

air conditioner

The present disclosure relates to an air conditioner having a repeater that supplies refrigerant supplied from a heat source device to indoor units.

An air conditioner that uses a refrigeration cycle has a refrigerant circuit in which a heat source unit having a compressor and a heat source side heat exchanger and an indoor unit having an expansion valve and a load side heat exchanger are connected by piping, and refrigerant flows. When the refrigerant evaporates or condenses in the load-side heat exchanger, the air conditioner absorbs or radiates heat from the air in the air-conditioned space, which is the object of heat exchange, and changes the pressure, temperature, etc. of the refrigerant flowing through the refrigerant circuit to perform air conditioning.

Also known is an air conditioner that includes a heat source device, a plurality of indoor units, and a repeater that distributes the refrigerant supplied from the heat source device to the plurality of indoor units. In such an air conditioner, the necessity of cooling operation or heating operation is automatically determined in each of the plurality of indoor units according to the set temperature and indoor temperature set by the remote controller, and cooling operation or heating operation is performed for each indoor unit. Simultaneous cooling and heating operation is performed. As an air conditioner that performs simultaneous cooling and heating operation, Patent Document 1 discloses a configuration in which a relay device between a heat source unit and an indoor unit switches between a flow of refrigerant during cooling operation and a flow of refrigerant during heating operation by two electromagnetic valves.

Japanese Patent No. 6895901

In the configuration of Patent Document 1, when power supply to the air conditioner is stopped in order to draw a vacuum, the electromagnetic valve of the repeater closes. Therefore, in order to make it possible to evacuate the gas branch pipe that connects the relay unit and the indoor unit, it is necessary to provide an orifice, for example, in the cooling switching solenoid valve. However, when an orifice is provided in the cooling switching solenoid valve, part of the refrigerant supplied from the compressor during heating operation passes through the cooling switching solenoid valve orifice and flows into the low-pressure pipe without passing through the indoor unit, resulting in a decrease in the heating capacity of the indoor unit. On the other hand, if the diameter of the orifice is reduced in order to suppress the deterioration of the heating capacity, the flow rate of air flowing through the orifice decreases when the entire air conditioner is evacuated, and it takes time to evacuate. Therefore, in the conventional tall type, there is a trade-off relationship between the improvement of the heating capacity and the reduction of the evacuation time, and there is a problem that it is difficult to achieve both of them.

The present disclosure solves the problems described above, and provides an air conditioner capable of suppressing a decrease in heating capacity and reducing the evacuation time.

The air conditioning apparatus according to the present disclosure comprises: a heat source unit having a compressor, a flow path switching valve and a heat source side heat exchanger; an indoor unit having a load side flow control valve and a load side heat exchanger and performing cooling operation or heating operation; a repeater connected to the heat source unit by a low pressure pipe and a high pressure pipe, connected to the indoor unit by a gas branch pipe and a liquid branch pipe, and supplying refrigerant supplied from the heat source unit to the indoor unit; When the indoor unit is in a heating operation, the branch unit is connected to the gas branch pipe and the low pressure pipe, and has an expansion valve whose degree of opening can be adjusted.

According to the air conditioner of the present disclosure, by providing an expansion valve whose opening degree can be adjusted at the branch of the repeater, the low-pressure pipe can be closed during heating operation, and the gas branch pipe and the low-pressure pipe can be communicated to open the low-pressure pipe when stopped. As a result, it is possible to suppress a decrease in the heating capacity and reduce the evacuation time.

2 is a refrigerant circuit diagram of the air conditioner according to Embodiment 1. FIG. 4 is a graph showing the relationship between the control amount and the degree of opening of the three-way electric expansion valve according to Embodiment 1. FIG. FIG. 3 is a refrigerant circuit diagram showing the state of the air conditioner according to Embodiment 1 during cooling only operation. FIG. 2 is a refrigerant circuit diagram showing the state of the air conditioner according to Embodiment 1 during heating only operation. FIG. 3 is a refrigerant circuit diagram showing a state of the air conditioner according to Embodiment 1 during cooling-main operation. FIG. 2 is a refrigerant circuit diagram showing a state of the air conditioner according to Embodiment 1 during heating main operation. 4 is a flow chart showing the control operation of the three-way electric expansion valve according to Embodiment 1; FIG. 7 is a refrigerant circuit diagram of an air conditioner according to Embodiment 2; 9 is a flow chart showing control operations of a heating on-off valve and a cooling expansion valve according to Embodiment 2. FIG.

Embodiments will be described below based on the drawings. In addition, in each figure, the same reference numerals denote the same or corresponding parts, and this is common throughout the specification. Also, the forms of the constituent elements shown in the entire specification are merely examples and are not limited to these descriptions. Furthermore, in the drawings below, the size relationship of each component may differ from the actual size.

Embodiment 1.
FIG. 1 is a refrigerant circuit diagram of an air conditioner 1 according to Embodiment 1. FIG. As shown in FIG. 1, the air conditioner 1 includes a heat source device 100, a plurality of indoor units 300a and 300b, a repeater 200, and a control device 10. In Embodiment 1, a configuration in which two indoor units 300a and 300b are connected to one heat source device 100 will be described, but the number of heat source devices 100 and repeaters 200 may be two or more. Also, the number of indoor units may be one or three or more.

(Configuration of air conditioner)
As shown in FIG. 1, the air conditioner 1 is configured by connecting a heat source device 100, indoor units 300a and 300b, and a relay device 200. As shown in FIG. The heat source device 100 has a function of supplying heat to the two indoor units 300a and 300b. The indoor units 300a and 300b are connected in parallel and have the same configuration. The indoor units 300 a and 300 b have a function of cooling or heating an air-conditioned space such as a room with heat supplied from the heat source unit 100 . The relay device 200 is interposed between the heat source device 100 and the indoor units 300a and 300b, and has a function of switching the flow of refrigerant supplied from the heat source device 100 in response to requests from the indoor units 300a and 300b and supplying the refrigerant to the indoor units 300a and 300b.

The heat source device 100 and the relay device 200 are connected on the high pressure side by a high pressure pipe 402 through which a high pressure refrigerant flows, and are connected on the low pressure side by a low pressure pipe 401 through which a low pressure refrigerant flows. Further, the repeater 200 and the indoor units 300a and 300b are connected by gas branch pipes 403a and 403b and liquid branch pipes 404a and 404b, respectively. Refrigerant in a gas state mainly flows through the gas branch pipes 403a and 403b. Liquid refrigerant mainly flows through the liquid branch pipes 404a and 404b.

(Heat source machine 100)
The heat source device 100 includes a compressor 101 , a flow path switching valve 102 , a heat source side heat exchange unit 120 , an accumulator 104 , and a heat source side flow adjustment unit 140 . The compressor 101 is a fluid machine that draws in low-pressure gas refrigerant, compresses it, and discharges it as high-pressure gas refrigerant. The compressor 101 is, for example, an inverter-driven compressor with an adjustable operating frequency. The channel switching valve 102 is a four-way valve that switches the channel of the refrigerant discharged from the compressor 101 . Note that the flow path switching valve 102 may be configured by combining a two-way valve, a three-way valve, or the like.

The heat source side heat exchange unit 120 includes a main pipe 114, a heat source side heat exchanger 103, a heat source side blower 111, a bypass pipe 113, a heat source side flow control valve 109, and a bypass flow control valve 110. The heat source side heat exchanger 103 is a heat exchanger that performs heat exchange between the refrigerant flowing inside and the air blown by the heat source side blower 111 . The heat source side heat exchanger 103 functions as an evaporator or a condenser. The heat source side heat exchanger 103 may be, for example, a water-cooled heat exchanger that exchanges heat between water or brine and a refrigerant.

The heat source side blower 111 is a propeller fan, cross flow fan, or multi-blade centrifugal fan that supplies air to the heat source side heat exchanger 103 . The heat exchange capacity is controlled by controlling the rotational speed of the heat source side blower 111 . Note that when the heat source side heat exchanger 103 is of a water-cooled type, the heat source side blower 111 is omitted, and a pump for circulating the heat medium is provided instead.

The main pipe 114 has one end connected to the flow path switching valve 102 and the other end connected to the high pressure pipe 402, and the heat source side heat exchanger 103 and the heat source side flow control valve 109 are provided. The bypass pipe 113 has one end connected to the flow path switching valve 102 and the other end connected to the high pressure pipe 402 , and is connected in parallel to the main pipe 114 . The refrigerant flowing through the bypass pipe 113 does not pass through the heat source side heat exchanger 103 and is not heat-exchanged.

The heat source side flow control valve 109 is connected in series with the heat source side heat exchanger 103 in the main pipe 114 and adjusts the flow rate of the refrigerant flowing through the main pipe 114 to reduce the pressure. The heat source side flow control valve 109 is configured by, for example, a two-way electric expansion valve whose opening degree can be adjusted. The bypass flow control valve 110 is provided in the bypass pipe 113 and adjusts the flow rate of the refrigerant flowing through the bypass pipe 113 to reduce the pressure. The bypass flow regulating valve 110 is composed of, for example, an electric expansion valve whose degree of opening can be adjusted.

The accumulator 104 is provided between the flow path switching valve 102 and the suction port of the compressor 101 . The accumulator 104 has a refrigerant storage function of storing excess refrigerant, and a gas-liquid separation function of separating the gas-liquid two-phase refrigerant flowing into the accumulator 104, discharging the gas refrigerant to the compressor 101, and retaining the liquid refrigerant.

The heat source side passage adjustment unit 140 has a third check valve 105, a fourth check valve 106, a fifth check valve 107, and a sixth check valve . The third check valve 105 is provided in a pipe connecting the heat source side heat exchange unit 120 and the high pressure pipe 402 and allows the refrigerant to flow from the heat source side heat exchange unit 120 toward the high pressure pipe 402 . The fourth check valve 106 is provided in a pipe connecting the flow path switching valve 102 of the heat source device 100 and the low pressure pipe 401 and allows the refrigerant to flow from the low pressure pipe 401 toward the flow path switching valve 102 . The fifth check valve 107 is provided in a pipe connecting the flow path switching valve 102 of the heat source device 100 and the high pressure pipe 402 and allows the refrigerant to flow from the flow path switching valve 102 toward the high pressure pipe 402 . The sixth check valve 108 is provided in a pipe connecting the heat source side heat exchange unit 120 and the low pressure pipe 401 and allows the refrigerant to flow from the low pressure pipe 401 toward the heat source side heat exchange unit 120 .

Also, the heat source device 100 is provided with a discharge pressure sensor 126 . The discharge pressure sensor 126 is provided in a pipe connecting the flow path switching valve 102 and the discharge side of the compressor 101 and detects the pressure of the refrigerant discharged from the compressor 101 . The discharge pressure sensor 126 transmits a signal of the detected discharge pressure to the control device 10 .

Also, the heat source device 100 is provided with a suction pressure sensor 127 . The suction pressure sensor 127 is provided in a pipe connecting the flow path switching valve 102 and the accumulator 104 and detects the pressure of the refrigerant sucked into the compressor 101 . The suction pressure sensor 127 transmits a detected suction pressure signal to the control device 10 .

Note that the discharge pressure sensor 126 and the suction pressure sensor 127 may each have a storage device or the like. In this case, each pressure sensor accumulates detected pressure data in a storage device or the like for a predetermined period, and transmits a signal including the accumulated pressure data to the control device 10 at predetermined intervals.

In addition, the heat source device 100 is provided with refrigerant enclosures 131 and 132 . The refrigerant enclosing part 131 is provided in a pipe connecting the flow path switching valve 102 and the discharge side of the compressor 101 , and enables refrigerant encapsulation or evacuation from the discharge side of the compressor 101 . The refrigerant enclosing part 132 is provided in a pipe that connects the flow path switching valve 102 and the accumulator 104 , and enables refrigerant encapsulation or vacuum drawing from the suction side of the compressor 101 . The refrigerant sealed portions 131 and 132 are configured by, for example, check joints.

( Indoor units 300a and 300b)
The indoor units 300a and 300b respectively include load- side heat exchangers 301a and 301b that function as condensers or evaporators, and load-side flow control valves 302a and 302b that adjust the flow rate of the refrigerant flowing through the indoor units 300a and 300b. The load- side heat exchangers 301a and 301b are heat exchangers that exchange heat between refrigerant flowing inside and air blown by an indoor fan (not shown). The load- side heat exchangers 301a and 301b may be water-cooled heat exchangers that exchange heat between water or brine and a refrigerant, for example.

The load-side flow control valves 302a and 302b adjust the flow rate of the refrigerant flowing into or out of the load- side heat exchangers 301a and 301b to reduce the pressure. The load-side flow control valves 302a and 302b are composed of, for example, two-way electric expansion valves whose opening can be adjusted. The degree of opening of the load-side flow control valves 302a and 302b during cooling is controlled by the controller 10 based on the degree of superheat on the outlet side of the load- side heat exchangers 301a and 301b. In addition, the degree of opening of the load-side flow control valves 302a and 302b during heating is controlled by the controller 10 based on the degree of supercooling on the outlet side of the load- side heat exchangers 301a and 301b.

The indoor units 300a and 300b are provided with gas pipe temperature sensors 304a and 304b and liquid pipe temperature sensors 303a and 303b, respectively. Gas pipe temperature sensors 304a and 304b are provided between load side heat exchangers 301a and 301b and repeater 200, respectively. The gas pipe temperature sensors 304a and 304b detect the temperature of the refrigerant flowing through the gas branch pipes 403a and 403b connecting the load side heat exchangers 301a and 301b and the repeater 200 . The gas pipe temperature sensors 304 a and 304 b are composed of, for example, thermistors, and send signals of detected temperatures to the control device 10 .

The liquid pipe temperature sensors 303a and 303b are provided between the load side heat exchangers 301a and 301b and the load side flow control valves 302a and 302b, respectively. The liquid pipe temperature sensors 303a and 303b detect the temperature of refrigerant flowing through pipes connecting the load side heat exchangers 301a and 301b and the load side flow control valves 302a and 302b. The liquid tube temperature sensors 303 a and 303 b are composed of, for example, thermistors, and transmit signals of detected temperatures to the control device 10 .

The gas pipe temperature sensors 304a and 304b and the liquid pipe temperature sensors 303a and 303b may each have a storage device or the like. In this case, each temperature sensor accumulates detected temperature data in a storage device or the like for a predetermined period, and transmits a signal including the accumulated temperature data to the control device 10 at predetermined intervals.

(Relay machine 200)
The repeater 200 includes a first branch portion 240, a second branch portion 250, a gas-liquid separator 201, a relay bypass pipe 209, a first flow control valve 204, a second flow control valve 205, a first heat exchange portion 206, and a second heat exchange portion 207.

The first branch 240 is connected to the gas branch pipes 403a and 403b on one side and to the low pressure pipe 401 and the high pressure pipe 402 on the other. The first branch portion 240 connects the gas branch pipes 403a and 403b to the low-pressure pipe 401 or the high-pressure pipe 402 so that the direction of refrigerant flow during cooling operation is different from that during heating operation. The first branch 240 includes three-way electric expansion valves 202a and 202b whose opening is adjustable.

The three-way electric expansion valve 202a is connected to the gas branch pipe 403a, the high pressure pipe 402, and the low pressure pipe 401. The three-way electric expansion valve 202b is connected to the gas branch pipe 403b, the high pressure pipe 402 and the low pressure pipe 401. The three-way electric expansion valves 202a and 202b have the function of switching the flow direction of the refrigerant and the function of adjusting the flow rate of the refrigerant. Specifically, the three-way electric expansion valve 202a has a first flow path that connects the gas branch pipe 403a and the low-pressure pipe 401, and a second flow path that connects the gas branch pipe 403a and the high-pressure pipe 402. Similarly, the three-way electric expansion valve 202b has a first flow path that connects the gas branch pipe 403b and the low-pressure pipe 401, and a second flow path that connects the gas branch pipe 403b and the high-pressure pipe 402. By controlling the opening degrees of the three-way electric expansion valves 202a and 202b by the control device 10, the first flow path and the second flow path are opened and closed, and the flow rate of the refrigerant flowing through the first flow path and the second flow path is adjusted.

When the indoor unit 300a performs cooling operation, the opening degree of the three-way electric expansion valve 202a is controlled so as to open the first channel that communicates the gas branch pipe 403a and the low-pressure pipe 401 and close the second channel. Further, when the indoor unit 300a performs the heating operation, the opening degree of the three-way electric expansion valve 202a is controlled so as to open the second passage that communicates the gas branch pipe 403a and the high-pressure pipe 402 and close the first passage. Similarly, when the indoor unit 300b performs cooling operation, the three-way electric expansion valve 202b is controlled to open the first flow path that communicates the gas branch pipe 403b and the low-pressure pipe 401 and close the second flow path. Further, when the indoor unit 300b performs heating operation, the three-way electric expansion valve 202b is controlled to open the second flow path connecting the gas branch pipe 403b and the high-pressure pipe 402 and close the first flow path.

The second branch 250 is connected to the liquid branch pipes 404a and 404b on one side and to the low pressure pipe 401 and the high pressure pipe 402 on the other. The second branch portion 250 connects the liquid branch pipes 404a and 404b to the low-pressure pipe 401 or the high-pressure pipe 402 so that the direction of refrigerant flow during cooling operation is different from that during heating operation. The second branch 250 has first check valves 210a and 210b and second check valves 211a and 211b.

One of the first check valves 210a and 210b is connected to the liquid branch pipes 404a and 404b, and the other is connected to the high pressure pipe 402, allowing the refrigerant to flow from the high pressure pipe 402 to the liquid branch pipes 404a and 404b.

One of the second check valves 211a and 211b is connected to the liquid branch pipes 404a and 404b, and the other is connected to the low pressure pipe 401, allowing the refrigerant to flow from the liquid branch pipes 404a and 404b toward the low pressure pipe 401.

The gas-liquid separator 201 separates a gas state refrigerant and a liquid state refrigerant, the inflow side is connected to the high-pressure pipe 402, the gas outflow side is connected to the first branch portion 240, and the liquid outflow side is connected to the second branch portion 250. The relay bypass pipe 209 connects the second branch portion 250 and the low pressure pipe 401 . The first flow control valve 204 is connected to the liquid outflow side of the gas-liquid separator 201, and is composed of, for example, a two-way electric expansion valve whose opening degree can be adjusted. The first flow control valve 204 adjusts the flow rate of the liquid refrigerant flowing out of the gas-liquid separator 201 to reduce the pressure.

The first heat exchange section 206 is provided between the liquid outflow side of the gas-liquid separator 201 and the first flow control valve 204 and in the relay bypass pipe 209 . The first heat exchange section 206 exchanges heat between the liquid refrigerant flowing out of the gas-liquid separator 201 and the refrigerant flowing through the relay bypass pipe 209 . The second heat exchange section 207 is provided downstream of the first flow control valve 204 and the relay bypass pipe 209 . The second heat exchange section 207 exchanges heat between the refrigerant flowing out of the first flow control valve 204 and the refrigerant flowing through the relay bypass pipe 209 .

The second flow control valve 205 is connected to the upstream side of the second heat exchange section 207 in the relay bypass pipe 209, and is composed of, for example, a two-way electric expansion valve whose opening can be adjusted. The second flow control valve 205 adjusts the flow rate of the refrigerant that has flowed into the relay bypass pipe 209 among the refrigerant that has flowed out of the second heat exchange section 207 to reduce the pressure.

Here, the upstream sides of the first check valves 210 a and 210 b are connected to the downstream side of the second heat exchange section 207 and the relay bypass pipe 209 . Therefore, the refrigerant flowing out of the second heat exchange section 207 is divided into refrigerant heading to the first check valves 210 a and 210 b and refrigerant flowing into the relay bypass pipe 209 . Further, downstream sides of the second check valves 211 a and 211 b are connected between the first flow control valve 204 and the upstream side of the second heat exchange section 207 . That is, the refrigerant flowing out of the second check valves 211a and 211b flows into the second heat exchange section 207 and is heat-exchanged, and then flows into the first check valves 210a and 210b and the refrigerant flowing into the relay bypass pipe 209.

The repeater 200 is also provided with a first pressure sensor 231 , a second pressure sensor 232 , and a relay bypass temperature sensor 208 . The first pressure sensor 231 is provided between the first heat exchange section 206 and the upstream side of the first flow control valve 204 and detects the pressure of the refrigerant on the liquid outflow side of the gas-liquid separator 201 . The first pressure sensor 231 transmits a detected pressure signal to the control device 10 .

The second pressure sensor 232 is provided between the downstream side of the first flow control valve 204 and the second heat exchange section 207, and detects the pressure of the refrigerant flowing out of the first flow control valve 204. The second pressure sensor 232 transmits a detected pressure signal to the control device 10 . The opening of the first flow control valve 204 is adjusted by the controller 10 so that the difference between the pressure detected by the first pressure sensor 231 and the pressure detected by the second pressure sensor 232 is constant.

The relay bypass temperature sensor 208 is provided on the relay bypass pipe 209 and detects the temperature of the refrigerant flowing through the relay bypass pipe 209 . The relay bypass temperature sensor 208 is composed of, for example, a thermistor or the like, and transmits a detected temperature signal to the control device 10 . The degree of opening of the second flow control valve 205 is adjusted by the control device 10 based on at least one of the pressure detected by the first pressure sensor 231, the pressure detected by the second pressure sensor 232, and the temperature detected by the relay bypass temperature sensor 208.

Note that the first pressure sensor 231, the second pressure sensor 232, and the relay bypass temperature sensor 208 may have a storage device or the like. In this case, each pressure sensor and temperature sensor accumulates the detected pressure or temperature data in a storage device or the like for a predetermined period, and transmits a signal including the accumulated pressure or temperature data to the control device 10 every predetermined period.

(Refrigerant)
In the air conditioner 1, the inside of the piping is filled with refrigerant. Refrigerants include, for example, natural refrigerants such as carbon dioxide (CO ₂ ), hydrocarbons, and helium; chlorine-free CFC alternative refrigerants such as HFC410A, HFC407C, and HFC404A; and CFC refrigerants such as R22 and R134a used in existing products. HFC407C is a non-azeotropic mixed refrigerant in which HFCs R32, R125, and R134a are mixed at ratios of 23 wt %, 25 wt %, and 52 wt %, respectively. Further, the interior of the pipe of the air conditioner 1 may be filled with a heat medium instead of the refrigerant. The heat medium is, for example, water or brine.

(control device 10)
The control device 10 controls the operation of the air conditioner 1 as a whole. The control device 10 is composed of a computer having a memory for storing data and programs required for control and a CPU for executing the programs, dedicated hardware such as ASIC or FPGA, or both. The control device 10 controls the driving frequency of the compressor 101, the heat source side blower 111, and the indoor units 300a and 300b based on the detection information received from the gas pipe temperature sensors 304a and 304b, the liquid pipe temperature sensors 303a and 303b, the first pressure sensor 231, the second pressure sensor 232, the relay bypass temperature sensor 208, the discharge pressure sensor 126, and the suction pressure sensor 127, and instructions from a remote controller (not shown). The number of rotations of an indoor fan (not shown) provided in , the switching of the flow path switching valve 102, the opening of the three-way electric expansion valves 202a and 202b, the heat source side flow control valve 109, the bypass flow control valve 110, the load side flow control valves 302a and 302b, the first flow control valve 204 and the opening of the second flow control valve 205, etc. are controlled.

Also, the control device 10 may calculate the cooling capacity or heating capacity in the cooling main operation and the heating main operation from the discharge pressure detected by the discharge pressure sensor 126 or the suction pressure detected by the suction pressure sensor 127. Alternatively, the control device 10 may calculate the cooling capacity or heating capacity in the cooling main operation and the heating main operation using the evaporation temperature and the condensation temperature obtained from the temperatures detected by the gas pipe temperature sensors 304a and 304b and the liquid pipe temperature sensors 303a and 303b.

Although the control device 10 is mounted on the heat source device 100 in FIG. 1, it may be mounted on either the relay device 200 or the indoor unit 300a or 300b, or may be provided separately from the heat source device 100, the relay device 200, or the indoor unit 300a or 300b. Alternatively, the heat source device 100, the relay device 200, and the indoor units 300a and 300b may each include a control device, and may be connected to each other by wireless or wired communication so as to transmit and receive various data.

Next, the operation of the three-way electric expansion valves 202a and 202b of the first branch portion 240 will be described. FIG. 2 is a graph showing the relationship between the control amount and the degree of opening of the three-way electric expansion valve 202a according to the first embodiment. The relationship between the control amount and the opening of the three-way electric expansion valve 202b is the same as the relationship between the control amount and the opening of the three-way electric expansion valve 202a shown in FIG. In FIG. 2, the vertical axis is the degree of opening of the three-way electric expansion valve 202a, and the horizontal axis is the control amount transmitted from the control device 10 to the three-way electric expansion valve 202a. The "control amount" here corresponds to the number of pulses of the pulse signal transmitted from the control device 10 to the three-way electric expansion valve 202a.

In FIG. 2, in the three-way electric expansion valve 202a, when the control amount is less than P1, the first flow path communicating between the gas branch pipe 403a and the low-pressure pipe 401 is opened, and the second flow path communicating between the gas branch pipe 403a and the high-pressure pipe 402 is closed. When the control amount is the minimum control amount Pmin, the opening of the first flow path of the three-way electric expansion valve 202a becomes the maximum opening A1, and as the control amount increases, the opening of the first flow path of the three-way electric expansion valve 202a decreases.

Next, when the control amount is greater than or equal to P1 and less than P2, both the first flow path and the second flow path of the three-way electric expansion valve 202a are closed regardless of the control amount. Further, when the control amount is P2 or more, the second flow path communicating between the gas branch pipe 403a and the high-pressure pipe 402 is opened, and the first flow path communicating between the gas branch pipe 403a and the low-pressure pipe 401 is closed. When the control amount is the maximum control amount Pmax, the opening of the second flow path of the three-way electric expansion valve 202a becomes the maximum opening A1, and as the control amount decreases, the opening of the second flow path of the three-way electric expansion valve 202a decreases.

(Operation of air conditioner)
Next, the operation of the air conditioner 1 will be described. The air conditioner 1 has, as operation modes, a cooling only operation, a heating only operation, a cooling main operation, and a heating main operation. The cooling-only operation is a mode in which all of the indoor units 300a and 300b perform the cooling operation. The heating only operation is a mode in which all of the indoor units 300a and 300b perform the heating operation. The cooling main operation is a mode in which the capacity of the cooling operation is larger than the capacity of the heating operation among the simultaneous cooling and heating operations. The heating-dominant operation is a mode in which the capacity of the heating operation is larger than the capacity of the cooling operation among the simultaneous cooling and heating operations. The control device 10 performs cooling-only operation, heating-only operation, cooling-dominant operation, or heating-dominant operation in accordance with the operation request to the indoor units 300a and 300b. Each operation will be described with reference to FIGS. 3 to 6. FIG. 3 to 6, the high-pressure refrigerant is indicated by solid line arrows, and the low-pressure refrigerant is indicated by broken line arrows. In addition, in FIGS. 3 to 6, among the check valves, the check valves through which the refrigerant does not flow are shown in black.

(All cooling operation)
First, the cooling only operation will be explained. FIG. 3 is a refrigerant circuit diagram showing the state of the air conditioner 1 according to Embodiment 1 during cooling only operation. In the cooling only operation, all of the indoor units 300a and 300b perform the cooling operation. As shown in FIG. 3, the high-temperature and high-pressure gas refrigerant discharged from the compressor 101 passes through the flow path switching valve 102, and is heat-exchanged with the outdoor air blown by the heat source-side blower 111 in the heat source-side heat exchanger 103 to be condensed and liquefied. The condensed and liquefied refrigerant then passes through the heat source side flow control valve 109 , the third check valve 105 and the high-pressure pipe 402 and reaches the gas-liquid separator 201 . Here, since the bypass flow control valve 110 is fully closed, no refrigerant flows through the bypass pipe 113 .

Then, the refrigerant is separated into a gas state refrigerant and a liquid state refrigerant by the gas-liquid separator 201, and the liquid state refrigerant flows out from the liquid outflow side, flows through the first heat exchange section 206, the first flow control valve 204, and the second heat exchange section 207 in order, and branches at the second branch section 250. The branched refrigerant flows into the indoor units 300a and 300b through the first check valves 210a and 210b and the liquid branch pipes 404a and 404b, respectively. In full cooling operation, the liquid branch pipes 404a and 404b have a lower pressure than the high pressure pipe 402, so no refrigerant flows through the second check valves 211a and 211b.

Then, the refrigerants that have flowed into the indoor units 300a and 300b are reduced to low pressure by the load side flow control valves 302a and 302b that are controlled based on the degree of superheat on the outlet side of the load side heat exchangers 301a and 301b. The depressurized refrigerant flows into the load- side heat exchangers 301a and 301b, where it is heat-exchanged with the indoor air and evaporates. At that time, the room in which the indoor units 300a and 300b are installed is cooled. Then, the gaseous refrigerant flows into the first branch portion 240 of the repeater 200 through the gas branch pipes 403a and 403b.

During the cooling only operation, the control device 10 controls the opening degrees of the three-way electric expansion valves 202a and 202b so that the first flow path communicating with the low-pressure pipe 401 is opened and the second flow path communicating with the high-pressure pipe 402 is closed. Therefore, the refrigerant that has flowed into the first branch portion 240 passes through the first flow paths of the three-way electric expansion valves 202 a and 202 b, then merges and passes through the low-pressure pipe 401 .

Also, part of the refrigerant that has passed through the second heat exchange section 207 flows into the relay bypass pipe 209 . The refrigerant that has flowed into the relay bypass pipe 209 is decompressed to a low pressure by the second flow control valve 205, and then heat-exchanged with the refrigerant that has passed through the first flow control valve 204 in the second heat exchange section 207, i.e., the refrigerant before branching to the relay bypass pipe 209, and evaporates. Furthermore, in the first heat exchange section 206, the refrigerant is heat-exchanged with the refrigerant before flowing into the first flow rate control valve 204, and is evaporated. The evaporated refrigerant flows into the low-pressure pipe 401 and joins the refrigerant that has passed through the three-way electric expansion valves 202a and 202b. After that, the merged refrigerant is sucked into the compressor 101 through the fourth check valve 106 , the flow path switching valve 102 and the accumulator 104 .

(All heating operation)
Next, the heating only operation will be explained. FIG. 4 is a refrigerant circuit diagram showing the state of the air-conditioning apparatus 1 according to Embodiment 1 during heating only operation. In the heating only operation, all of the indoor units 300a and 300b perform the heating operation. As shown in FIG. 4 , the high-temperature and high-pressure gas refrigerant discharged from the compressor 101 passes through the flow switching valve 102 , the fifth check valve 107 and the high-pressure pipe 402 and reaches the gas-liquid separator 201 .

The refrigerant is separated into a gas state refrigerant and a liquid state refrigerant by the gas-liquid separator 201 , and the gas state refrigerant flows out from the gas outlet side of the gas-liquid separator 201 and flows into the first branch portion 240 . During the heating only operation, the control device 10 controls the opening degrees of the three-way electric expansion valves 202a and 202b so that the second flow path communicating with the high-pressure pipe 402 is opened and the first flow path communicating with the low-pressure pipe 401 is closed. Therefore, the refrigerant that has flowed into the first branch portion 240 passes through the second flow paths of the three-way electric expansion valves 202a and 202b, the gas branch pipes 403a and 403b, and flows into the indoor units 300a and 300b, respectively.

The refrigerant that has flowed into the indoor units 300a and 300b is heat-exchanged with the indoor air in the load- side heat exchangers 301a and 301b, respectively, and is condensed and liquefied. At that time, the room in which the indoor units 300a and 300b are installed is heated. Then, the condensed and liquefied refrigerant is decompressed through load side flow control valves 302a and 302b controlled based on the degree of subcooling on the outlet side of load side heat exchangers 301a and 301b, respectively.

The refrigerant decompressed by the load-side flow control valves 302a and 302b passes through the liquid branch pipes 404a and 404b and the second check valves 211a and 211b of the second branch portion 250, respectively, and then joins. At this time, no refrigerant flows through the first check valves 210a and 210b. The merged refrigerant passes through the second heat exchange section 207, flows into the relay bypass pipe 209, and is decompressed to a low pressure by the second flow control valve 205. After that, the decompressed refrigerant flows out from the second branching portion 250 and is heat-exchanged with the refrigerant before branching to the relay bypass pipe 209 to evaporate.

Furthermore, the refrigerant passes through the first heat exchange section 206 . Note that the first flow control valve 204 is closed during the heating only operation. The refrigerant that has passed through the first heat exchange section 206 flows into the low-pressure pipe 401, passes through the sixth check valve 108, is decompressed by the heat source side flow control valve 109, and is heat-exchanged with the outdoor air blown by the heat source side blower 111 in the heat source side heat exchanger 103 to be evaporated and gasified. The gasified refrigerant is sucked into the compressor 101 through the flow switching valve 102 and the accumulator 104 . Since the bypass flow control valve 110 is fully closed, no refrigerant flows through the bypass pipe 113 .

(cooling main operation)
Next, the cooling main operation will be explained. FIG. 5 is a refrigerant circuit diagram showing a state of the air-conditioning apparatus 1 according to Embodiment 1 during cooling-main operation. A case will be described below in which the indoor unit 300a performs the cooling operation and the indoor unit 300b performs the heating operation, and the cooling capacity is larger. As shown in FIG. 5 , the high-temperature, high-pressure gas refrigerant discharged from the compressor 101 passes through the flow path switching valve 102 and branches into refrigerant flowing into the main pipe 114 and refrigerant flowing into the bypass pipe 113 . In the cooling-dominant operation, the bypass flow control valve 110 is open.

The refrigerant that has flowed into the main pipe 114 exchanges heat with the outdoor air blown by the heat source side blower 111 in the heat source side heat exchanger 103 to condense and liquefy. The condensed and liquefied refrigerant is then decompressed by the heat source side flow control valve 109 . On the other hand, the refrigerant flowing into bypass pipe 113 is decompressed by bypass flow control valve 110 . The refrigerant that has flowed into the heat source side heat exchanger 103 and the refrigerant that has flowed into the bypass pipe 113 join in front of the third check valve 105 and pass through the third check valve 105 and the high-pressure pipe 402 to reach the gas-liquid separator 201 .

The refrigerant is separated into a gas state refrigerant and a liquid state refrigerant by the gas-liquid separator 201 . The liquid refrigerant flowing out from the liquid outflow side of the gas-liquid separator 201 passes through the first heat exchange section 206 , the first flow control valve 204 and the second heat exchange section 207 to reach the second branch section 250 . The refrigerant flows into the indoor unit 300a through the first check valve 210a of the second branch 250 and the liquid branch pipe 404a. Since the liquid branch pipe 404a has a lower pressure than the high pressure pipe 402, the refrigerant does not flow through the second check valve 211a.

Then, the refrigerant that has flowed into the indoor unit 300a is decompressed to a low pressure by the load side flow control valve 302a controlled based on the degree of superheat on the outlet side of the load side heat exchanger 301a. The depressurized refrigerant flows into the load-side heat exchanger 301a, where it is heat-exchanged with the indoor air and evaporates. At that time, the room in which the indoor unit 300a is installed is cooled. Then, the gaseous refrigerant flows into the first branch portion 240 of the repeater 200 through the gas branch pipe 403a.

The three-way electric expansion valve 202a connected to the indoor unit 300a that performs cooling operation in the cooling-main operation is controlled by the control device 10 so that the first flow path communicating with the low-pressure pipe 401 is opened and the second flow path communicating with the high-pressure pipe 402 is closed. Therefore, the refrigerant that has flowed into the first branch portion 240 flows into the low-pressure pipe 401 through the first flow path of the three-way electric expansion valve 202a.

On the other hand, the gaseous refrigerant flowing out from the gas outflow side of the gas-liquid separator 201 flows into the first branch portion 240 . The three-way electric expansion valve 202b connected to the indoor unit 300b that performs heating operation in the cooling-main operation is controlled by the control device 10 so that the second flow path communicating with the high-pressure pipe 402 is opened and the first flow path communicating with the low-pressure pipe 401 is closed. Therefore, the refrigerant that has flowed into the first branch portion 240 flows into the indoor unit 300b through the second flow path of the three-way electric expansion valve 202b and the gas branch pipe 403b.

The refrigerant that has flowed into the indoor unit 300b is heat-exchanged with the indoor air in the load-side heat exchanger 301b to be condensed and liquefied. At that time, the room in which the indoor unit 300b is installed is heated. Then, the condensed and liquefied refrigerant passes through the load side flow control valve 302b controlled based on the degree of subcooling on the outlet side of the load side heat exchanger 301b, and becomes an intermediate pressure liquid state between high pressure and low pressure. The refrigerant in the intermediate-pressure liquid state passes through the liquid branch pipe 404 b and the second check valve 211 b of the second branch portion 250 and flows into the second heat exchange portion 207 . At this time, the refrigerant does not flow through the first check valve 210b.

After that, the refrigerant flows into the relay bypass pipe 209 and is depressurized to a low pressure by the second flow rate control valve 205, and then heat-exchanged in the second heat exchange section 207 with the refrigerant that has passed through the first flow rate control valve 204, i.e., the refrigerant before branching to the relay bypass pipe 209, and evaporates. Furthermore, in the first heat exchange section 206, the refrigerant is heat-exchanged with the refrigerant before flowing into the first flow rate control valve 204, and is evaporated. The evaporated refrigerant flows into the low-pressure pipe 401 and joins with the refrigerant that has passed through the three-way electric expansion valve 202a. After that, the merged refrigerant is sucked into the compressor 101 through the fourth check valve 106 , the flow path switching valve 102 and the accumulator 104 .

(heating main operation)
Next, the heating main operation will be explained. FIG. 6 is a refrigerant circuit diagram showing a state of the air-conditioning apparatus 1 according to Embodiment 1 during heating-main operation. A case where the indoor unit 300a performs the cooling operation and the indoor unit 300b performs the heating operation and the heating capacity is larger will be described below. As shown in FIG. 6 , the high-temperature, high-pressure gas refrigerant discharged from the compressor 101 passes through the flow switching valve 102 , the fifth check valve 107 and the high-pressure pipe 402 , and reaches the gas-liquid separator 201 .

The refrigerant is separated into a gas state refrigerant and a liquid state refrigerant by the gas-liquid separator 201 . The gaseous refrigerant flowing out from the gas outflow side of the gas-liquid separator 201 flows into the first branch portion 240 . In the heating main operation, the three-way electric expansion valve 202b connected to the indoor unit 300b that performs the heating operation is controlled by the control device 10 so that the second flow path communicating with the high-pressure pipe 402 is opened and the first flow path communicating with the low-pressure pipe 401 is closed. Therefore, the refrigerant that has flowed into the first branch portion 240 flows into the indoor unit 300b through the second flow path of the three-way electric expansion valve 202b and the gas branch pipe 403b.

The refrigerant that has flowed into the indoor unit 300b is heat-exchanged with the indoor air in the load-side heat exchanger 301b to be condensed and liquefied. At that time, the room in which the indoor unit 300b is installed is heated. Then, the condensed and liquefied refrigerant passes through the load side flow control valve 302b controlled based on the degree of subcooling on the outlet side of the load side heat exchanger 301b, and becomes an intermediate pressure liquid state between high pressure and low pressure. The refrigerant in the intermediate-pressure liquid state passes through the liquid branch pipe 404 b and the second check valve 211 b of the second branch portion 250 and flows into the second heat exchange portion 207 . At this time, the refrigerant does not flow through the first check valve 210b. The refrigerant that has passed through the second check valve 211 b flows out from the liquid outflow side of the gas-liquid separator 201 and joins the liquid state refrigerant that has passed through the first heat exchange section 206 and the first flow control valve 204 . The merged refrigerant branches into refrigerant flowing into the second branch portion 250 and refrigerant flowing into the relay bypass pipe 209 .

The refrigerant that has flowed into the second branch portion 250 passes through the first check valve 210a and the liquid branch pipe 404a of the second branch portion 250 and flows into the indoor unit 300a. Since the liquid branch pipe 404a has a lower pressure than the high pressure pipe 402, the refrigerant does not flow through the second check valve 211a. Then, the refrigerant that has flowed into the indoor unit 300a is decompressed to a low pressure by the load side flow control valve 302a controlled based on the degree of superheat on the outlet side of the load side heat exchanger 301a. The depressurized refrigerant flows into the load-side heat exchanger 301a, where it is heat-exchanged with the indoor air and evaporates. At that time, the room in which the indoor unit 300a is installed is cooled. Then, the gaseous refrigerant flows into the first branch portion 240 of the repeater 200 through the gas branch pipe 403a.

The three-way electric expansion valve 202a connected to the indoor unit 300a that performs cooling operation during heating-dominant operation is controlled by the control device 10 so that the first flow path communicating with the low-pressure pipe 401 is opened and the second flow path communicating with the high-pressure pipe 402 is closed. Therefore, the refrigerant that has flowed into the first branch portion 240 flows through the first flow path of the three-way electric expansion valve 202 a and into the low-pressure pipe 401 .

On the other hand, the refrigerant that has flowed into the relay bypass pipe 209 is depressurized to a low pressure by the second flow control valve 205, and then heat-exchanged in the second heat exchange section 207 with the refrigerant that has flowed out of the second branching section 250, i.e., the refrigerant before branching to the relay bypass piping 209, and evaporates. Furthermore, in the first heat exchange section 206, the refrigerant is heat-exchanged with the refrigerant before flowing into the first flow rate control valve 204, and is evaporated. The evaporated refrigerant flows into the low-pressure pipe 401 and joins with the refrigerant that has passed through the three-way electric expansion valve 202a. After that, the merged refrigerant passes through the sixth check valve 108 and flows into the main pipe 114 and the bypass pipe 113 . In the heating-dominant operation, the bypass flow control valve 110 is open.

The refrigerant that has flowed into the main pipe 114 is depressurized by the heat source side flow control valve 109, exchanges heat with the outdoor air blown by the heat source side blower 111 in the heat source side heat exchanger 103, and evaporates. On the other hand, the refrigerant that has flowed into the bypass pipe 113 is decompressed by the bypass flow control valve 110 and then joins the refrigerant that has flowed out from the main pipe 114 . The merged refrigerant is sucked into the compressor 101 through the flow path switching valve 102 and the accumulator 104 .

(State of standstill)
Next, a case where the air conditioner 1 is stopped will be described. The refrigerant circuit diagram when the air conditioner 1 is stopped is the same as the refrigerant circuit diagram during the cooling only operation in FIG. 3 . When the air conditioner 1 is stopped, there is no operation request from the indoor units 300a and 300b, the compressor 101 is stopped, and the flow path switching valve 102 is switched so that the discharge pipe of the compressor 101 and the main pipe 114 are communicated. Also, the heat source side flow rate adjustment valve 109, the bypass flow rate adjustment valve 110, the first flow rate adjustment valve 204, and the second flow rate adjustment valve 205 are opened at preset opening degrees. The load side flow control valves 302a and 302b are closed.

Also, when the air conditioner 1 is stopped, the three-way electric expansion valves 202a and 202b are controlled by the control amount Pmin. That is, when the air conditioner 1 is stopped, the three-way electric expansion valves 202a and 202b are controlled so that the first flow path communicating with the low pressure pipe 401 is opened and the second flow path communicating with the high pressure pipe 402 is closed. In this state, the air conditioner 1 can be evacuated by connecting, for example, a vacuum pump to the refrigerant sealed portions 131 and 132 and activating the vacuum pump.

FIG. 7 is a flow chart showing the control operation of the three-way electric expansion valve 202a according to the first embodiment. The control operation of the three-way electric expansion valve 202b is also the same as the control operation of the three-way electric expansion valve 202a. The control device 10 determines the control amount of the three-way electric expansion valve 202a according to the operation mode required for the indoor unit 300a connected to the three-way electric expansion valve 202a. First, the control device 10 determines whether or not the heat source device 100 is in operation (S1). Here, when the compressor 101 is in operation, the control device 10 determines that the heat source device 100 is in operation. When the heat source device 100 is in operation (S1: YES), the control device 10 determines the state of the indoor unit 300a (S2). Here, the control device 10 determines whether the indoor unit 300a is requesting stop, cooling operation, or heating operation.

When the indoor unit 300a requests to stop (S2: stop), the control device 10 transmits a pulse signal of the control amount P1 to the three-way electric expansion valve 202a (S3). As a result, both the first flow path and the second flow path of the three-way electric expansion valve 202a are closed. That is, when the heat source unit 100 is in operation and the indoor unit 300a is stopped, the gas branch pipe 403a of the indoor unit 300a is closed.

When the indoor unit 300a requests heating operation (S2: heating), the control device 10 transmits a pulse signal of the control amount Pmax to the three-way electric expansion valve 202a (S4). As a result, the second flow path of the three-way electric expansion valve 202a is opened and the first flow path is closed. That is, when the heat source unit 100 is in operation and the indoor unit 300a performs heating operation, the gas branch pipe 403a of the indoor unit 300a and the high pressure pipe 402 are communicated.

When the indoor unit 300a requests cooling operation (S2: cooling), or when the heat source device 100 is not in operation (S1: NO), the control device 10 transmits a pulse signal of the control amount Pmin to the three-way electric expansion valve 202a (S5). As a result, the first flow path of the three-way electric expansion valve 202a is opened and the second flow path is closed. That is, when the heat source device 100 is in operation and the indoor unit 300a performs cooling operation, or when the heat source device 100 is stopped, the gas branch pipe 403a of the indoor unit 300a and the low pressure pipe 401 are communicated.

As described above, in the present embodiment, when the indoor units 300a and 300b request heating operation, the three-way electric expansion valves 202a and 202b of the repeater 200 communicate the gas branch pipes 403a and 403b with the high pressure pipe 402 to close the refrigerant flow to the low pressure pipe 401. As a result, the refrigerant flowing from the high-pressure pipe 402 is not bypassed from the three-way electric expansion valves 202a and 202b to the low-pressure pipe 401, and the reduction in heating capacity can be suppressed compared to the conventional air conditioner.

Also, when it is determined that the heat source device 100 is stopped, the three-way electric expansion valves 202a and 202b allow the gas branch pipes 403a and 403b and the low pressure pipe 401 to communicate with each other at the maximum degree of opening. By vacuuming in such a state, it is possible to secure a larger flow rate of air flowing through the gas branch pipes 403a and 403b and the low-pressure pipe 401 than in the conventional case, and the time required for vacuuming the air conditioner 1 can be reduced.

In addition, by using the three-way electric expansion valves 202a and 202b to switch the refrigerant flow during cooling operation and heating operation, it is possible to reduce the number of parts of the first branch portion 240, and the space occupied within the repeater 200 can also be reduced. Furthermore, when switching the flow of the refrigerant during cooling operation and heating operation with a plurality of valves for one indoor unit 300a, it is actually difficult to operate the plurality of valves at the same time, resulting in a time lag of several seconds. On the other hand, by switching one three-way electric expansion valve 202a for one indoor unit 300a, the control target becomes one, so there is no need to consider the occurrence of time lag.

Embodiment 2.
FIG. 8 is a refrigerant circuit diagram of an air conditioner 1A according to Embodiment 2. As shown in FIG. As shown in FIG. 8, an air conditioner 1A of Embodiment 2 differs from that of Embodiment 1 in the configuration of a first branch portion 240A of a repeater 200A. Other configurations of the air conditioner 1A are the same as those of the first embodiment.

As shown in FIG. 8, the first branch portion 240A of the repeater 200A of the present embodiment includes heating on-off valves 213a and 213b and cooling expansion valves 214a and 214b. One of the heating on-off valves 213 a and 213 b is connected to the gas branch pipes 403 a and 403 b , and the other is connected to the high pressure pipe 402 . One of the cooling expansion valves 214 a and 214 b is connected to the gas branch pipes 403 a and 403 b and the other is connected to the low pressure pipe 401 . The heating on-off valves 213a and 213b are, for example, electromagnetic valves. The cooling expansion valves 214a and 214b are composed of, for example, two-way electric expansion valves whose opening can be adjusted.

FIG. 9 is a flow chart showing control operations of the heating on-off valve 213a and the cooling expansion valve 214a according to the second embodiment. The control operation of the heating on-off valve 213b and the cooling expansion valve 214b is the same as the control operation of the heating on-off valve 213a and the cooling expansion valve 214a. The control device 10 determines the opening/closing of the heating on/off valve 213a and the opening of the cooling expansion valve 214a according to the operation mode required for the indoor unit 300a connected to the heating on/off valve 213a and the cooling expansion valve 214a.

First, the control device 10 determines whether the heat source equipment 100 is in operation (S21). Here, when the compressor 101 is in operation, it is determined that the heat source device 100 is in operation. If the heat source device 100 is in operation (S21: YES), the control device 10 determines the state of the indoor unit 300a (S22). Here, the control device 10 determines whether the indoor unit 300a is requesting stop, cooling operation, or heating operation.

When the indoor unit 300a requests to stop (S22: stop), the control device 10 closes both the heating on-off valve 213a and the cooling expansion valve 214a (S23). That is, when the heat source unit 100 is in operation and the indoor unit 300a is stopped, the gas branch pipe 403a of the indoor unit 300a is closed.

When the indoor unit 300a requests heating operation (S22: heating), the control device 10 opens the heating on-off valve 213a and closes the cooling expansion valve 214a (S24). Accordingly, when the heat source unit 100 is in operation and the indoor unit 300a performs heating operation, the gas branch pipe 403a of the indoor unit 300a and the high-pressure pipe 402 are communicated with each other.

When the indoor unit 300a requests cooling operation (S22: Cooling), or when the heat source device 100 is not in operation (S21: NO), the controller 10 closes the heating on-off valve 213a and opens the cooling expansion valve 214a (S25). Here, the control device 10 fully opens the cooling expansion valve 214a. Thereby, when the heat source device 100 is in operation and the indoor unit 300a performs cooling operation, or when the heat source device 100 is stopped, the gas branch pipe 403a of the indoor unit 300a and the low pressure pipe 401 are communicated.

As described above, also in the present embodiment, when it is determined that the indoor units 300a and 300b request heating operation, the gas branch pipes 403a and 403b and the high pressure pipe 402 are communicated, and the flow of refrigerant to the low pressure pipe 401 can be closed. Therefore, since the refrigerant flowing from the high-pressure pipe 402 does not bypass the cooling expansion valves 214a and 214b to the low-pressure pipe 401, the reduction in heating capacity can be suppressed compared to the conventional air conditioner.

Also, when it is determined that the heat source device 100 is stopped, the gas branch pipes 403a and 403b and the low-pressure pipe 401 can be communicated with each other at the maximum degree of opening. By vacuuming in such a state, it is possible to secure a larger flow rate of air flowing through the gas branch pipes 403a and 403b and the low-pressure pipe 401 than in the conventional case, and the time required for vacuuming the air conditioner 1 can be reduced.

Although the embodiments have been described above, the present disclosure is not limited to the above embodiments, and can be variously modified or combined without departing from the gist of the present disclosure. For example, in the first embodiment, when the indoor unit 300a requests to stop (S2: stop), the control device 10 is configured to transmit a pulse signal of the control amount P1 to the three-way electric expansion valve 202a.

Further, in Embodiment 1, when the heat source device 100 is not in operation (S1: NO), the control device 10 is configured to transmit a pulse signal of the control amount Pmin to the three-way electric expansion valve 202a. For example, when the refrigerant is expected to stagnate in the load-side heat exchanger 301a from the relay device 200 through the gas branch pipe 403a of the indoor unit 300a while the heat source device 100 is stopped, the control amount may be set larger than Pmin. As a result, the degree of opening of the three-way electric expansion valve 202a can be reduced, and the stagnation amount of the refrigerant can be suppressed.

Further, in Embodiment 2, instead of the heating on-off valves 213a and 213b, a heating expansion valve consisting of a two-way electric expansion valve whose opening degree can be adjusted may be used. In this case, when the indoor unit 300a requests to be stopped (S22: stop), the control device 10 closes both the heating expansion valve and the cooling expansion valve 214a. When the indoor unit 300a requests the heating operation (S22: heating), the control device 10 fully opens the heating expansion valve and closes the cooling expansion valve 214a. Furthermore, when the indoor unit 300a requests cooling operation (S22: cooling) or when the heat source device 100 is not in operation (S21: NO), the control device 10 closes the heating expansion valve and opens the cooling expansion valve 214a. Also in this case, the same effect as in the second embodiment can be obtained.

1, 1A air conditioner, 10 control device, 100 heat source machine, 101 compressor, 102 flow path switching valve, 103 heat source side heat exchanger, 104 accumulator, 105 third check valve, 106 fourth check valve, 107 fifth check valve, 108 sixth check valve, 109 heat source side flow control valve, 110 bypass flow control valve, 11 1 heat source side blower, 113 bypass pipe, 114 main pipe, 120 heat source side heat exchange unit, 126 discharge pressure sensor, 127 suction pressure sensor, 131, 132 refrigerant enclosure, 140 heat source side passage adjustment unit, 200, 200A repeater, 201 gas-liquid separator, 202a, 202b three-way electric expansion valve, 204 first flow rate adjustment valve, 20 5 second flow control valve, 206 first heat exchange section, 207 second heat exchange section, 208 relay bypass temperature sensor, 209 relay bypass pipe, 210a, 210b first check valve, 211a, 211b second check valve, 213a, 213b heating on-off valve, 214a, 214b cooling expansion valve, 231 first pressure sensor, 232 second Pressure sensors 240, 240A First branch 250 Second branch 300a, 300b Indoor units 301a, 301b Load side heat exchangers 302a, 302b Load side flow control valves 303a, 303b Liquid pipe temperature sensors 304a, 304b Gas pipe temperature sensors 401 Low pressure pipes 402 High pressure pipes 403a, 40 3b gas branch pipe, 404a, 404b liquid branch pipe.

Claims (8)

1. a heat source device having a compressor, a flow path switching valve, and a heat source side heat exchanger;
   an indoor unit having a load-side flow control valve and a load-side heat exchanger and performing cooling operation or heating operation;
   a repeater connected to the heat source unit by a low-pressure pipe and a high-pressure pipe, connected to the indoor unit by a gas branch pipe and a liquid branch pipe, and supplying the refrigerant supplied from the heat source unit to the indoor unit;
   a controller;
   The relay unit communicates the gas branch pipe and the low-pressure pipe when the indoor unit performs the cooling operation, and communicates the gas branch pipe and the high-pressure pipe when the indoor unit performs the heating operation.
   the branching portion is connected to the gas branch pipe and the low-pressure pipe, and has an expansion valve capable of adjusting the degree of opening;
   The controller controls the expansion valve so that the gas branch pipe and the low-pressure pipe communicate with each other when the heat source equipment is stopped.
2. The air conditioner according to claim 1, wherein the expansion valve is a three-way electric expansion valve having a first flow path that communicates the gas branch pipe and the low-pressure pipe, and a second flow path that communicates the gas branch pipe and the high-pressure pipe.
3. The control device is
   3. The air conditioner according to claim 2, wherein the three-way electric expansion valve is controlled to open the first flow path and close the second flow path when the heat source device is stopped.
4. The control device is
   4. The air conditioner according to claim 3, wherein the three-way electric expansion valve is controlled to close the first flow path and the second flow path when the heat source unit is in operation and the indoor unit is stopped.
5. The control device is
   5. The air conditioner according to claim 3 or 4, wherein the three-way electric expansion valve is controlled to open the first flow path and close the second flow path when the heat source device is in operation and the indoor unit performs cooling operation.
6. The control device is
   When the heat source unit is operating and the indoor unit performs heating operation, the three-way electric expansion valve is controlled to open the second flow path and close the first flow path. The air conditioner according to any one of claims 3 to 5.
7. The expansion valve is a cooling expansion valve composed of a two-way electric expansion valve,
   The air conditioner according to claim 1, wherein the branch portion further includes a heating on-off valve connected to the gas branch pipe and the high-pressure pipe.
8. The control device is
   8. The air conditioner according to claim 7, wherein when the heat source equipment is stopped, the cooling expansion valve is controlled so that the gas branch pipe and the low-pressure pipe are communicated, and the heating on-off valve is controlled so that the gas branch pipe and the high-pressure pipe are closed.

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