WO2021001869A1

WO2021001869A1 - Air conditioning device

Info

Publication number: WO2021001869A1
Application number: PCT/JP2019/026031
Authority: WO
Inventors: 侑哉森下
Original assignee: 三菱電機株式会社
Priority date: 2019-07-01
Filing date: 2019-07-01
Publication date: 2021-01-07
Also published as: CN114008393B; CN114008393A; GB202115484D0; GB2603246A; GB2603246B

Abstract

This air conditioning device comprises a relay that has a first decompression device. The relay has a flow path switching valve that is provided to first refrigerant piping connected between a compressor and a load-side heat exchanger, and bypass piping that is connected to the flow path switching valve at one end, and at the other end is connected to second refrigerant piping connected between the first decompression device and a heat source-side heat exchanger. The flow path switching valve has, as internal flow paths, a first flow path communicating the first refrigerant piping and the bypass piping, and a second flow path communicating the compressor and the load-side heat exchanger via the first refrigerant piping, and switches the internal flow paths such that one internal flow path among the first flow path and the second flow path is open while the other internal flow path is closed.

Description

Air conditioner

The present invention relates to an air conditioner provided with a repeater.

Patent Document 1 discloses an air conditioner including a repeater that relays between the outdoor unit and the indoor unit. In the air conditioner of Patent Document 1, a decompression device is housed in the repeater. Further, in the air conditioner of Patent Document 1, a plurality of indoor units are connected to a repeater, and the plurality of indoor units can be independently switched between start and stop.

JP-A-2015-135196

In the air conditioner, the amount of refrigerant circulating may be temporarily increased in order to maintain the operating capacity of the outdoor unit. In such a case, in the air conditioner of Patent Document 1, in order to maintain the amount of the refrigerant circulating in the indoor unit that is running, the refrigerant may be temporarily circulated in the indoor unit that is stopped. In this case, in the stopped indoor unit, the opening degree of the decompression device connected to the stopped indoor unit is connected to the operating indoor unit in order to suppress the temperature change in the space where the indoor unit is installed. It is adjusted to be smaller than the opening degree of the decompression device and to the minimum opening degree. However, when the opening degree of the decompression device is adjusted in this way, noise is generated when the refrigerant passes through the decompression device, which may reduce the quietness of the repeater.

The present invention solves the above-mentioned problems, and an object of the present invention is to provide an air conditioner capable of maintaining the quietness of a repeater.

The air conditioner of the present invention includes an outdoor unit having a heat source side heat exchanger, a compressor connected to the heat source side heat exchanger, a plurality of indoor units having a load side heat exchanger, and the heat source side. It has a first decompression device connected to a heat exchanger, includes a repeater connected to a part of the plurality of indoor units, and the repeater includes the compressor and the load side heat exchanger. A first refrigerant pipe connected between the first refrigerant pipe, a second refrigerant pipe connected between the first decompression device and the heat source side heat exchanger, and a flow path switching provided in the first refrigerant pipe. It has a valve and a bypass pipe having one end connected to the flow path switching valve and the other end connected to the second refrigerant pipe, and the flow path switching valve is the first on the side of the compressor. 1 The first flow path that communicates the refrigerant pipe and the bypass pipe, and the second flow that communicates the first refrigerant pipe on the compressor side and the first refrigerant pipe on the load side heat exchanger side. It has a path as an internal flow path, and one of the first flow path and the second flow path is opened and the other internal flow path is closed. The internal flow path is switched.

In the air conditioner of the present invention, since the repeater has the flow path switching valve and the bypass pipe, the inside of the flow path switching valve is prevented from flowing into the indoor unit when the indoor unit is stopped. The flow path can be switched to divert the refrigerant to the bypass pipe. That is, in the air conditioner of the present invention, when the indoor unit is stopped, the flow path can be switched so that the refrigerant does not pass through the first decompression device. Therefore, in the air conditioner of the present invention, since the repeater has the flow path switching valve and the bypass pipe, the noise of the first decompression device due to the passage of the refrigerant can be suppressed, so that the air can maintain the quietness of the repeater. A harmonizer can be provided.

It is the schematic which shows an example of the air conditioner which concerns on Embodiment 1. FIG. It is a schematic refrigerant circuit diagram which shows a part of the air conditioner of FIG. It is a flowchart which shows the control process of the flow path switching valve and the 1st decompression device at the time of defrosting operation which concerns on Embodiment 1. FIG. It is a flowchart which shows the control process of the flow path switching valve and the 1st pressure reducing device at the time of the oil recovery operation which concerns on Embodiment 2. It is a schematic refrigerant circuit diagram which shows an example of the refrigerant circuit of the air conditioner which concerns on Embodiment 3. FIG. It is a flowchart which shows the control process of the flow path switching valve and the 1st decompression device at the time of the refrigerant leakage detection which concerns on Embodiment 3. It is a schematic refrigerant circuit diagram which shows an example of the refrigerant circuit of the air conditioner which concerns on Embodiment 4. FIG. It is a flowchart which shows the control process of the flow path switching valve and the first decompression device when the indoor unit is stopped which concerns on Embodiment 4. FIG. It is a schematic refrigerant circuit diagram which shows an example of the refrigerant circuit of the air conditioner which concerns on Embodiment 5. FIG. It is a flowchart which shows the control process of the flow path switching valve, the 1st decompression device, and the 2nd decompression device at the time of heating operation of the air conditioner which concerns on Embodiment 5. It is a schematic refrigerant circuit diagram which shows an example of the refrigerant circuit of the air conditioner which concerns on Embodiment 6. It is an enlarged view of the branch pipe of FIG. FIG. 5 is an enlarged view showing a state in which a flow path switching valve and a bypass pipe are arranged in a refrigerant circuit of the air conditioner according to the sixth embodiment.

Embodiment 1.
The air conditioner 100 according to the first embodiment will be described. FIG. 1 is a schematic view showing an example of an air conditioner 100 according to the first embodiment. FIG. 2 is a schematic refrigerant circuit diagram showing a part of the air conditioner 100 of FIG. In the drawings below, the dimensional relationships and shapes of the constituent members may differ from the actual ones. Further, in the following drawings, the same members or parts or members or parts having the same functions are designated by the same reference numerals or omitted.

As shown in FIG. 1, the air conditioner 100 includes an outdoor unit 10, a plurality of indoor units 20, and a repeater 30. The outdoor unit 10 and the repeater 30 are connected by a refrigerant pipe. Further, a part of the plurality of indoor units 20 is connected to the outdoor unit 10 via the repeater 30, and the other part of the plurality of indoor units 20 is connected to the outdoor unit 10 without passing through the repeater 30. It is directly connected. For example, the repeater 30 is connected to an indoor unit 20 provided in a space where quietness is required, for example, a space such as a president's room, a conference room, or an office room. Further, a space where quietness is not required, for example, an indoor unit 20 such as an elevator hall or a storage room is directly connected to the outdoor unit 10 without going through a repeater 30. Although the number of the outdoor unit 10 and the repeater 30 is limited to one in FIG. 1, a plurality of outdoor units 10 may be provided. Further, the number of indoor units 20 connected to the repeater 30 may be one. Further, the refrigerant pipe may be an existing refrigerant pipe in the property where the air conditioner 100 is installed, or may be a refrigerant pipe newly installed when the air conditioner 100 is installed.

In the following description, the "cooling operation" refers to an operation mode of the air conditioner 100 that allows a low-temperature and low-pressure two-phase refrigerant to flow into the indoor unit 20. Further, the “heating operation” refers to an operation mode of the air conditioner 100 that allows a high-temperature and high-pressure vapor-phase refrigerant to flow into the indoor unit 20.

The outdoor unit 10 has a compressor 1, a refrigerant flow path switching device 2, and a heat source side heat exchanger 3. In the outdoor unit 10, the compressor 1 and the heat source side heat exchanger 3 are connected by a refrigerant pipe via a refrigerant flow path switching device 2.

The compressor 1 is a fluid machine that compresses the sucked low-pressure refrigerant and discharges it as a high-pressure refrigerant. For example, a variable-capacity compressor such as a reciprocating compressor, a rotary compressor, or a scroll compressor is used.

The refrigerant flow path switching device 2 uses an electric signal to switch the refrigerant flow path switching device 2 in response to the switching from the cooling operation of the air conditioning device 100 to the heating operation or the switching from the heating operation to the cooling operation of the air conditioning device 100. It is an electric device that can switch the internal refrigerant flow path. In FIG. 2, the refrigerant flow path inside the refrigerant flow path switching device 2 during the cooling operation is shown by a dotted line, and the refrigerant flow path inside the refrigerant flow path switching device 2 during the heating operation is shown by a solid line. There is. As the refrigerant flow path switching device 2, for example, a four-way valve that applies the operation of a solenoid valve is used. Further, the refrigerant flow path switching device 2 may be a switching device in which a two-way valve or a three-way valve is combined. In the air conditioner 100, when only one of the cooling operation and the heating operation is performed, the refrigerant flow path switching device 2 can be omitted.

The heat source side heat exchanger 3 is a heat transfer device that transfers and exchanges heat energy between two fluids having different heat energies. The heat source side heat exchanger 3 functions as a condenser during the cooling operation and as an evaporator during the heating operation. As the heat source side heat exchanger 3, an air-cooled heat exchanger such as a fin-and-tube heat exchanger or a plate fin heat exchanger, or a shell-and-tube heat exchanger, a plate heat exchanger, or a double-tube heat exchanger. A water-cooled heat exchanger such as an exchanger is used. In the air conditioner 100, the condenser may be referred to as a radiator.

The indoor unit 20 has a load side heat exchanger 4. The load-side heat exchanger 4 is a heat transfer device that transfers and exchanges heat energy between two fluids having different heat energies, similarly to the heat source-side heat exchanger 3 described above. The load side heat exchanger 4 functions as an evaporator during the cooling operation and as a condenser during the heating operation. As the load side heat exchanger 4, an air-cooled heat exchanger such as a fin-and-tube heat exchanger or a plate fin heat exchanger is used.

The repeater 30 is connected between the outdoor unit 10 and the indoor unit 20 by a refrigerant pipe. The repeater 30 is one of the first refrigerant pipe 5a, which is one of the refrigerant pipes connecting the compressor 1 and the load side heat exchanger 4, and one of the refrigerant pipes connected to the heat source side heat exchanger 3. It has a second refrigerant pipe 5b, which is a part. Branch refrigerant pipes corresponding to the number of load side heat exchangers 4 of the indoor unit 20 are connected to the first refrigerant pipe 5a and the second refrigerant pipe 5b, respectively. Further, the repeater 30 has a first decompression device 6, a capillary tube 7, and a strainer 8.

The first decompression device 6 is an expansion device that expands and depressurizes a high-pressure liquid phase refrigerant. As the first decompression device 6, an expander, a temperature type automatic expansion valve, a linear electronic expansion valve, or the like is used. The expander is a mechanical expansion valve that employs a diaphragm for the pressure receiving part. The temperature type automatic expansion valve is an expansion device that adjusts the amount of refrigerant according to the degree of superheat of the gas phase refrigerant on the suction side of the compressor 1. The linear electronic expansion valve is an expansion device whose opening degree can be adjusted in multiple stages or continuously, and is also abbreviated as LEV. The first decompression device 6 is arranged in each of the branched refrigerant pipes connected to the second refrigerant pipe 5b.

The capillary tube 7 is a capillary refrigerant pipe which is composed of an elongated copper pipe and allows a required amount of refrigerant to pass through pipe resistance to reduce the pressure of the refrigerant. The capillary tube 7 is connected in series with the first decompression device 6 to each of the branched refrigerant pipes connected to the second refrigerant pipe 5b. The capillary tube 7 is arranged in the branched refrigerant pipe on the side of the indoor unit 20 with respect to the first decompression device 6. In the air conditioner 100, the capillary tube 7 assists the decompression function of the first decompression device 6, and can be omitted.

The strainer 8 is a filter for filtering out dust, impurities, etc. contained in a refrigerant such as sludge generated during the operation of the compressor 1. The strainer 8 is provided to prevent clogging of the first decompression device 6 and the capillary tube 7. The strainer 8 is provided in the second refrigerant pipe 5b and each of the branched refrigerant pipes connected to the second refrigerant pipe 5b so as to sandwich both sides of the refrigerant pipe in which the first decompression device 6 and the capillary tube 7 are arranged. It is provided in. For example, if the compressor 1 can suppress the generation of sludge, the strainer 8 can be omitted.

The air conditioner 100 may have a configuration other than that described above. For example, the air conditioner 100 may include equipment other than those described above, such as a supercooling heat exchanger, an accumulator, or an oil separator. Further, the indoor unit 20 may have a plurality of load side heat exchangers 4.

In the air conditioner 100, the compressor 1, the heat source side heat exchanger 3, the first decompression device 6, and the load side heat exchanger 4 are connected by piping to form a refrigerant circuit in which the refrigerant circulates. Here, an outline of the operation of the refrigerant circuit of the air conditioner 100 during the cooling operation will be described.

During the cooling operation, the refrigerant flow path switching device 2 controls the path of the refrigerant flow path inside the refrigerant flow path switching device 2 as shown by the dotted line in FIG.

In the outdoor unit 10, the high-temperature and high-pressure vapor-phase refrigerant discharged from the compressor 1 flows into the heat source side heat exchanger 3 via the refrigerant flow path inside the refrigerant flow path switching device 2. The heat source side heat exchanger 3 functions as a condenser during the cooling operation. The high-temperature and high-pressure gas-phase refrigerant that has flowed into the heat source-side heat exchanger 3 is heat-exchanged with a heat medium such as outside air at the heat-source-side heat exchanger 3 and flows out as a high-pressure liquid-phase refrigerant. The high-pressure liquid-phase refrigerant flowing out of the heat source side heat exchanger 3 flows out from the outdoor unit 10 and flows into the repeater 30.

The high-pressure liquid-phase refrigerant that has flowed into the repeater 30 flows into the first decompression device 6 via the second refrigerant pipe 5b. The high-pressure vapor-phase refrigerant flowing into the first decompression device 6 is expanded and decompressed by the first decompression device 6, and flows out from the first decompression device 6 as a low-temperature low-pressure two-phase refrigerant. The low-temperature and low-pressure two-phase refrigerant flowing out of the first decompression device 6 flows out from the repeater 30 and flows into the indoor unit 20.

The low temperature and low pressure two-phase refrigerant that has flowed into the indoor unit 20 flows into the load side heat exchanger 4. The load side heat exchanger 4 functions as an evaporator in the cooling operation. The low-pressure two-phase refrigerant that has flowed into the load-side heat exchanger 4 is heat-exchanged with a heat medium such as indoor air at the load-side heat exchanger 4, and flows out as a low-pressure gas-phase refrigerant. The refrigerant flowing out of the load side heat exchanger 4 may be a low-pressure, highly dry two-phase refrigerant. The low-pressure vapor-phase refrigerant flowing out of the load-side heat exchanger 4 flows out from the indoor unit 20 and flows into the outdoor unit 10 via the first refrigerant pipe 5a of the repeater 30.

The low-pressure vapor-phase refrigerant that has flowed into the outdoor unit 10 is sucked into the compressor 1 via the refrigerant flow path inside the refrigerant flow path switching device 2. The low-pressure vapor-phase refrigerant sucked into the compressor 1 is compressed by the compressor 1 and discharged from the compressor 1 as a high-temperature and high-pressure vapor-phase refrigerant. During the cooling operation of the air conditioner 100, the above cycle is repeated.

The outline of the operation of the refrigerant circuit of the air conditioner 100 during the heating operation will be described. During the heating operation, the refrigerant flow path switching device 2 controls the path of the refrigerant flow path inside the refrigerant flow path switching device 2 as shown by the solid line in FIG.

The high-temperature and high-pressure vapor-phase refrigerant discharged from the compressor 1 flows out from the outdoor unit 10 via the refrigerant flow path inside the refrigerant flow path switching device 2, and flows out to the first refrigerant pipe 5a of the repeater 30. It flows into the indoor unit 20 through the indoor unit 20.

The high-temperature and high-pressure vapor-phase refrigerant that has flowed into the indoor unit 20 flows into the load-side heat exchanger 4. The load side heat exchanger 4 functions as a condenser in the heating chamber operation. The high-temperature, high-pressure gas-phase refrigerant that has flowed into the load-side heat exchanger 4 is heat-exchanged with a heat medium such as indoor air by the load-side heat exchanger 4, and flows out as a high-pressure liquid-phase refrigerant. The high-pressure liquid-phase refrigerant flowing out of the load-side heat exchanger 4 flows out of the indoor unit 20 and flows into the repeater 30.

The high-pressure liquid-phase refrigerant that has flowed into the repeater 30 flows into the first decompression device 6. The high-pressure liquid-phase refrigerant flowing into the first decompression device 6 is expanded and decompressed by the first decompression device 6, and flows out from the first decompression device 6 as a low-temperature low-pressure two-phase refrigerant. The low-temperature and low-pressure two-phase refrigerant flowing out of the first decompression device 6 flows out from the repeater 30 via the second refrigerant pipe 5b and flows into the outdoor unit 10.

The low temperature and low pressure two-phase refrigerant that has flowed into the outdoor unit 10 flows into the heat source side heat exchanger 3. The heat source side heat exchanger 3 functions as an evaporator during the heating operation. The low-temperature, low-pressure two-phase refrigerant that has flowed into the heat source-side heat exchanger 3 is heat-exchanged with a heat medium such as outside air at the heat-source-side heat exchanger 3, and flows out as a low-pressure gas-phase refrigerant. The refrigerant flowing out of the heat source side heat exchanger 3 may be a low-pressure, highly dry two-phase refrigerant.

The low-pressure vapor-phase refrigerant flowing out of the heat source side heat exchanger 3 is sucked into the compressor 1 via the refrigerant flow path inside the refrigerant flow path switching device 2. The low-pressure vapor-phase refrigerant sucked into the compressor 1 is compressed by the compressor 1 and discharged from the compressor 1 as a high-temperature and high-pressure vapor-phase refrigerant. During the heating operation of the air conditioner 100, the above cycle is repeated.

Next, the bypass circuit of the repeater 30 will be described. The repeater 30 includes a bypass circuit including a flow path switching valve 50 and a bypass pipe 52.

The flow path switching valve 50 is an electric device provided in the middle of the first refrigerant pipe 5a and switching between the refrigerant circuit and the bypass circuit by an electric signal. The flow path switching valve 50 bypasses the first port 50a connected to the first refrigerant pipe 5a on the outdoor unit 10 side, the second port 50b connected to the first refrigerant pipe 5a on the indoor unit 20 side, and the bypass. It has a third port 50c connected to one end of the pipe 52. Further, the flow path switching valve 50 includes a first flow path that communicates between the first port 50a and the third port 50c, and a second flow path that communicates between the first port 50a and the second port 50b. Is provided as an internal flow path. In the flow path switching valve 50, the first flow path is opened and the second flow path is closed, so that the refrigerant flow path between the first refrigerant pipe 5a on the outdoor unit 10 side and the bypass pipe 52 communicates with each other. To do. Further, in the flow path switching valve 50, the first flow path is closed and the second flow path is opened, so that the first refrigerant pipe 5a on the outdoor unit 10 side and the first refrigerant pipe on the indoor unit 20 side are opened. The refrigerant flow path with and from 5a communicates with each other. As the flow path switching valve 50, for example, a three-way valve that applies the operation of a solenoid valve is used. Further, the flow path switching valve 50 may be an electric device in which one port of the four-way valve is closed, or an electric device in which a two-way valve is combined.

In the bypass pipe 52, one end of the bypass pipe 52 is connected to the third port 50c of the flow path switching valve 50, and the other end of the bypass pipe 52 is connected to the second refrigerant pipe 5b. The repeater 30 only has a small electric device such as the first decompression device 6, and the miniaturization of the repeater 30 is easier than that of the outdoor unit 10 or the indoor unit 20. Therefore, the length of the bypass pipe 52 can be shortened by reducing the distance between the first refrigerant pipe 5a and the second refrigerant pipe 5b housed inside the repeater 30.

By having the flow path switching valve 50 and the bypass pipe 52, the repeater 30 opens the first flow path of the flow path switching valve 50 when all the indoor units 20 are stopped, and the second flow. By closing the path, the refrigerant can be diverted to the bypass pipe 52. That is, according to this configuration, when all the indoor units 20 are stopped, the flow path can be switched so that the refrigerant does not pass through the first decompression device 6, and the noise of the first decompression device 6 due to the passage of the refrigerant. Therefore, it is possible to provide an air conditioner 100 capable of maintaining the quietness of the repeater 30.

Next, the control process of the flow path switching valve 50 will be described. The air conditioner 100 includes a control device 70, and the switching of the internal flow path of the flow path switching valve 50 is performed by the control device 70.

The control device 70 is configured as a microcomputer or a microcomputer processing unit equipped with dedicated hardware, a central processing unit, a memory, or the like. The control device 70 is configured as, for example, an embedded control circuit board, and is housed in an electric component box of the outdoor unit 10. The control device 70 is wired or wirelessly connected to the first temperature sensor 72a, the compressor 1, the refrigerant flow path switching device 2, the first depressurizing device 6, and the flow path switching valve 50. Further, in the air conditioner 100, the control device 70 may be provided only in any one of the outdoor unit 10, the indoor unit 20, and the repeater 30. Further, in the air conditioner 100, the control device 70 may be provided in two or more of the outdoor unit 10, the indoor unit 20, and the repeater 30, and may be bidirectionally wired or wirelessly communicated with each other. In the following drawings including FIG. 2, the communication line connected to the control device 70 by wire or wirelessly is not shown.

The control device 70 opens the internal flow path of one of the first flow path and the second flow path of the flow path switching valve 50 and closes the other flow path. A control signal for switching the internal flow path of the 50 is transmitted to the flow path switching valve 50. Further, the control device 70 transmits a control signal for adjusting the opening degree of the first decompression device 6 to the first decompression device 6. It is assumed that the control device 70 includes all the electric circuits that adjust the opening degree of the first decompression device 6 and transmit a signal for switching the internal flow path of the flow path switching valve 50.

The control device 70 receives the temperature information detected by the first temperature sensor 72a. The first temperature sensor 72a detects the temperature information of the refrigerant sucked into the compressor 1 during the cooling operation or the temperature information of the refrigerant discharged from the compressor 1 during the heating operation. As the first temperature sensor 72a, for example, a sensor containing a semiconductor material such as a thermistor or a metal material such as a resistance temperature detector is used.

Further, the control device 70 is configured to control the frequency of the compressor 1, control the internal flow path of the refrigerant flow path switching device 2 when switching between the cooling operation and the heating operation, or start and stop the air conditioning device 100. it can.

FIG. 3 is a flowchart showing a control process of the flow path switching valve 50 and the first decompression device 6 during the defrosting operation according to the first embodiment. Here, the "defrosting operation" refers to an operation mode in which a high-temperature and high-pressure refrigerant is supplied to the heat source-side heat exchanger 3 in order to suppress frost formation on the heat-source-side heat exchanger 3, and mainly starts a heating operation. Performed before or during heating operation. The defrosting operation is performed, for example, by switching the internal flow path of the refrigerant flow path switching device 2 to the internal flow path during the cooling operation during the heating operation. Further, the defrosting operation may be performed by supplying the high-temperature and high-pressure refrigerant from the compressor 1 to the heat source side heat exchanger 3 via the bypass circuit without switching the refrigerant flow path switching device 2. Further, the control process of FIG. 3 can be set to be performed at regular time intervals, for example, every 30 minutes. Further, in the normal heating operation before the control process, the internal flow path of the flow path switching valve 50 is in a state where the first flow path is closed and the second flow path is open.

In step S11, the control device 70 determines whether or not the air conditioner 100 performs the defrosting operation. Whether or not to perform the defrosting operation is determined based on, for example, the temperature of the heat source side heat exchanger 3. If it is determined that the defrosting operation is not performed, the control process ends.

When it is determined in step S11 that the defrosting operation is performed, in step S12, the control device 70 opens the first flow path of the flow path switching valve 50 and closes the second flow path of the flow path switching valve 50. , The opening degree of the first decompression device 6 is controlled to be fully closed. In FIG. 2, the flow of the refrigerant when the control process of step S12 is performed is indicated by an arrow. At this time, since the high-temperature vapor-phase refrigerant does not flow in the indoor unit 20 that has been normally operated, for example, a thermo operation that only blows air to the load side heat exchanger 4 is performed. The high-pressure liquid refrigerant returns from the repeater 30 to the outdoor unit 10 via the bypass pipe 52, but since the refrigerant merges with the refrigerant returned from the other indoor unit 20, the compressor 1 is used. It is possible to adjust the low pressure gas phase refrigerant to be inhaled.

When the defrosting operation is performed by the air conditioner 100, the amount of refrigerant discharged from the compressor 1 temporarily increases as compared with the heating operation, and the repeater to which the indoor unit 20 that is stopped is connected. The amount of refrigerant flowing into 30 also increases. However, according to this control process, the refrigerant discharged from the compressor 1 and flowing into the heat source side heat exchanger 3 is returned to the outdoor unit 10 via the bypass pipe 52, so that the refrigerant inflow amount increases. 1 It is not necessary to open the decompression device 6. Therefore, according to this control process, the noise of the first decompression device 6 due to the passage of the refrigerant can be suppressed, so that the air conditioner 100 capable of maintaining the quietness of the repeater 30 can be provided.

Further, according to this control process, since it is not necessary to open the first decompression device 6 due to the increase in the amount of refrigerant inflow, the refrigerant does not flow to the stopped indoor unit 20. Therefore, it is possible to prevent the temperature of the air-conditioned space in which the stopped indoor unit 20 is installed from dropping, so that the comfort of the air-conditioned space can be maintained.

When a plurality of repeaters 30 are connected to the air conditioner 100, the control device 70 performs the control process in step S12 by the repeater 30 having the smallest total operating capacity of the connected indoor unit 20. Can be done. Further, the control device 70 determines whether or not the repeater 30 satisfies the stoptable condition during the control process of step S11 and step S12, and some of the repeaters 30 satisfying the stoptable condition. It can be configured to perform the control process of step S12. The stoptable condition may be determined, for example, based on the threshold value of the operating capacity of the indoor unit 20 connected to the repeater 30. For example, the control device 70 may be configured so that it can be determined that the stoptable condition is satisfied when all the indoor units 20 connected to the repeater 30 are stopped.

Embodiment 2.
In the second embodiment, the control process of the flow path switching valve 50 and the first pressure reducing device 6 during the oil recovery operation will be described with reference to FIG. FIG. 4 is a flowchart showing a control process of the flow path switching valve 50 and the first pressure reducing device 6 during the oil recovery operation according to the second embodiment. Since the configuration of the air conditioner 100 is the same as that of the first embodiment, the description thereof will be omitted.

Here, the "oil recovery operation" refers to an operation mode of the air conditioner 100 that recovers the lubricating oil discharged by the compressor 1 together with the refrigerant into the inside of the compressor 1. When the cooling operation is performed for a long time and with a low load, the lubricating oil discharged together with the refrigerant from the compressor 1 is particularly heat exchange on the heat source side of the refrigerant pipes connecting the outdoor unit 10 and the repeater 30. It stays in the so-called liquid side pipe arranged between the vessel 3 and the first decompression device 6. This is because the flow velocity of the liquid refrigerant flowing through the liquid side piping is slower than that of the gas phase refrigerant, and the liquid lubricating oil contained in the liquid phase refrigerant precipitates in the refrigerant piping than the gaseous lubricating oil contained in the gas phase refrigerant. Because it is easy to do. The oil recovery operation is performed by increasing the operating frequency of the compressor 1 as compared with the normal cooling operation in order to recover the lubricating oil accumulated outside the compressor 1. The control process of FIG. 4 can be set to be performed when the vehicle is operated at a frequency lower than that of the normal operation for a long time, for example, 5 hours or more. Further, during the normal cooling operation before the control process, the internal flow path of the flow path switching valve 50 is in a state where the first flow path is closed and the second flow path is open.

In step S21, the control device 70 determines whether or not the oil recovery operation is performed by the air conditioner 100. Whether or not to perform the oil recovery operation is determined by, for example, a predetermined criterion based on the entire load of the air conditioner 100 and the operation time under the load. If it is determined that the oil recovery operation is not performed, the control process ends.

When it is determined in step S21 that the oil recovery operation is performed, in step S22, the control device 70 opens the first flow path of the flow path switching valve 50 and closes the second flow path of the flow path switching valve 50. , The opening degree of the first decompression device 6 is controlled to be fully closed. The flow of the refrigerant when the control process of step S22 is performed is in the direction of the arrow in FIG. 2 as in the first embodiment. At this time, since the low-temperature and low-pressure two-phase refrigerant does not flow in the indoor unit 20 that has been normally operated, for example, a thermo operation that only blows air to the load side heat exchanger 4 is performed. The high-pressure liquid refrigerant returns from the repeater 30 to the outdoor unit 10 via the bypass pipe 52, but since the refrigerant merges with the refrigerant returned from the other indoor unit 20, the compressor 1 is used. It is possible to adjust the low pressure gas phase refrigerant to be inhaled.

When the oil recovery operation is performed by the air conditioner 100, the operating frequency of the compressor 1 is increased, so that the amount of refrigerant discharged from the compressor 1 temporarily increases as compared with the normal cooling operation. The amount of refrigerant flowing into the repeater 30 to which the stopped indoor unit 20 is connected also increases. However, according to this control process, the refrigerant discharged from the compressor 1 and flowing into the heat source side heat exchanger 3 is returned to the outdoor unit 10 via the bypass pipe 52, so that the refrigerant inflow amount increases. 1 It is not necessary to open the decompression device 6. Therefore, according to this control process, the noise of the first decompression device 6 due to the passage of the refrigerant can be suppressed, so that the air conditioner 100 capable of maintaining the quietness of the repeater 30 can be provided.

When a plurality of repeaters 30 are connected to the air conditioner 100, the control device 70 performs the control process in step S22 at the repeater 30 having the smallest total operating capacity of the connected indoor unit 20. Can be done. Further, the control device 70 determines whether or not the repeater 30 satisfies the stoptable condition during the control process of step S21 and step S22, and some of the repeaters 30 satisfying the stoptable condition. It can be configured to perform the control process of step S22. The stoptable condition may be determined, for example, based on the threshold value of the operating capacity of the indoor unit 20 connected to the repeater 30. For example, the control device 70 may be configured so that it can be determined that the stoptable condition is satisfied when all the indoor units 20 connected to the repeater 30 are stopped.

Embodiment 3.
The configuration of the air conditioner 100 according to the third embodiment will be described with reference to FIG. FIG. 5 is a schematic refrigerant circuit diagram showing an example of the refrigerant circuit of the air conditioner 100 according to the third embodiment. In the air conditioner 100 according to the third embodiment, the indoor unit 20 is provided with the refrigerant leakage detection device 74. The control device 70 receives the refrigerant leakage detection information from the refrigerant leakage detection device 74. As the refrigerant leakage detection device 74, for example, a refrigerant leakage detection sensor is provided. As the refrigerant leak detection sensor, for example, a gas sensor such as a semiconductor type gas sensor, a heat ray type semiconductor type gas sensor, or an infrared type gas sensor is used. Further, the refrigerant leakage detection sensor may be an oxygen concentration type gas sensor that detects a decrease in oxygen concentration, or may be a flammable gas detection type gas sensor that detects flammable gas. The refrigerant leakage detection device 74 may be provided in an information input device for the indoor unit 20, for example, a remote controller. Further, the refrigerant leakage detection device 74 is not limited to the refrigerant leakage detection sensor, and may be, for example, indirectly detecting the leakage of the refrigerant from an abnormality in the temperature of the refrigerant pipe of the indoor unit 20. Since the other configurations of the air conditioner 100 are the same as those in the first and second embodiments, the description thereof will be omitted.

FIG. 6 is a flowchart showing a control process of the flow path switching valve 50 and the first decompression device 6 at the time of detecting the refrigerant leakage according to the third embodiment. The control process of FIG. 6 can be set to be performed at regular intervals, for example, every 5 minutes. Further, in the normal cooling operation or heating operation before the control process, the internal flow path of the flow path switching valve 50 is in a state where the first flow path is closed and the second flow path is open. And.

In step S31, the control device 70 determines whether or not the refrigerant leakage is detected in the indoor unit 20. If it is determined that no refrigerant leakage has been detected, the control process ends. When it is determined in step S31 that the refrigerant leakage is detected in the indoor unit 20, in step S32, the control device 70 opens the first flow path of the flow path switching valve 50 and the second flow path switching valve 50. Control is performed so that the flow path is closed and the opening degree of the first decompression device 6 is fully closed. The flow of the refrigerant when the control process of step S32 is performed is in the direction of the dotted arrow in FIG. 5 in the case of cooling operation, and in the direction of the solid arrow in FIG. 5 in the case of heating operation. Since the refrigerant returning from the repeater 30 to the outdoor unit 10 via the bypass pipe 52 merges with the refrigerant returned from the other indoor unit 20, the low-pressure vapor-phase refrigerant is sucked by the compressor 1. It is possible to adjust.

According to this control process, the refrigerant discharged from the compressor 1 is returned to the outdoor unit 10 via the bypass pipe 52 without flowing into the indoor unit 20, so that the refrigerant leakage from the indoor unit 20 can be suppressed. ..

Embodiment 4.
The configuration of the air conditioner 100 according to the fourth embodiment will be described with reference to FIG. FIG. 7 is a schematic refrigerant circuit diagram showing an example of the refrigerant circuit of the air conditioner 100 according to the fourth embodiment. In the air conditioner 100 according to the fourth embodiment, the indoor unit 20 is provided with the second temperature sensor 72b and the third temperature sensor 72c. The second temperature sensor 72b is a sensor that measures the temperature of air after heat exchange by the heat source side heat exchanger 3, and functions as a room temperature sensor. The third temperature sensor 72c is a sensor that measures the temperature of the high-pressure liquid refrigerant or the two-phase refrigerant during the heating operation, and functions as a supercooling temperature sensor. The control device 70 receives the detection information of the refrigerant leakage from the second temperature sensor 72b and the third temperature sensor 72c. As the second temperature sensor 72b and the third temperature sensor 72c, for example, a sensor containing a semiconductor material such as a thermistor or a metal material such as a resistance temperature detector is used. Since the other configurations of the air conditioner 100 are the same as those in the first and second embodiments, the description thereof will be omitted. Further, in the air conditioner 100, one of the second temperature sensor 72b and the third temperature sensor 72c may be omitted.

FIG. 8 is a flowchart showing a control process of the flow path switching valve 50 and the first decompression device 6 when the indoor unit 20 according to the fourth embodiment is stopped. The control process of FIG. 8 can be set to be performed at regular intervals, for example, every 30 minutes during the heating operation of the air conditioner 100. Further, in the normal heating operation before the control process, the internal flow path of the flow path switching valve 50 is in a state where the first flow path is closed and the second flow path is open.

In step S41, the control device 70 determines whether or not the refrigerant is retained in the indoor unit 20. For example, when the temperature detected by the second temperature sensor 72b continues at 30 ° C. for 3 minutes, it is determined that the refrigerant is retained in the heat source side heat exchanger 3 in the state of a two-phase refrigerant. Alternatively, when the temperature detected by the third temperature sensor 72c continues to be constant for 3 minutes after rising, it is determined that the refrigerant is retained in the heat source side heat exchanger 3 in the state of a two-phase refrigerant. Will be done. If it is determined that the refrigerant does not stay, the control process ends.

When it is determined in step S41 that the refrigerant is retained in the indoor unit 20, in step S42, the control device 70 opens the first flow path of the flow path switching valve 50, and the flow path switching valve 50 is the first. 2 The flow path is closed, and the opening degree of the first decompression device 6 is controlled to be fully opened. The flow of the refrigerant when the control process of step S42 is performed is in the direction of the arrow in FIG. Since the refrigerant returning from the repeater 30 to the outdoor unit 10 via the bypass pipe 52 merges with the refrigerant returned from the other indoor unit 20, the low-pressure vapor-phase refrigerant is sucked by the compressor 1. It is possible to adjust.

According to this control process, the refrigerant discharged from the compressor 1 is returned to the outdoor unit 10 via the bypass pipe 52 without flowing into the indoor unit 20. Therefore, according to this control process, it is possible to suppress the temperature rise in the air-conditioned space in which the stopped indoor unit 20 is installed. Further, the refrigerant staying in the indoor unit 20 can be returned to the outdoor unit 10 by being attracted by the flow of the refrigerant returned to the outdoor unit 10 via the bypass pipe 52. Therefore, it is possible to suppress a decrease in the amount of refrigerant in the indoor unit 20 due to the retention of the refrigerant in the indoor unit 20, and it is possible to secure the amount of refrigerant required when the heating operation of the indoor unit 20 is restarted.

Embodiment 5.
The configuration of the air conditioner 100 according to the fifth embodiment will be described with reference to FIG. FIG. 9 is a schematic refrigerant circuit diagram showing an example of the refrigerant circuit of the air conditioner 100 according to the fifth embodiment. In the air conditioner 100 according to the fifth embodiment, the bypass pipe 52 is provided with the second decompression device 54. The second decompression device 54 is an expansion device that expands and depressurizes the high-pressure refrigerant. As the second pressure reducing device 54, a linear electronic expansion valve or the like is used. Since the other configurations of the air conditioner 100 are the same as those in the first and second embodiments, the description thereof will be omitted.

FIG. 10 is a flowchart showing a control process of the flow path switching valve 50, the first decompression device 6, and the second decompression device 54 during the heating operation of the air conditioner 100 according to the fifth embodiment. The control process of FIG. 10 can be set to be performed at regular intervals, for example, every 30 minutes during the heating operation of the air conditioner 100. Further, in the normal heating operation before the control process, the internal flow path of the flow path switching valve 50 is in a state where the first flow path is closed and the second flow path is open.

In step S51, the control device 70 determines whether or not the indoor unit 20 connected to the repeater 30 is stopped. If it is determined that the indoor unit 20 has not stopped, the control process ends. When it is determined in step S51 that the indoor unit 20 is stopped, in step S52, the control device 70 opens the first flow path of the flow path switching valve 50, and the second flow of the flow path switching valve 50. Control is performed so that the road is closed and the opening degree of the first decompression device 6 is fully closed. Further, in step S53, the control device 70 adjusts the opening degree of the second decompression device 54 so that the high-pressure gas phase refrigerant flowing into the bypass pipe 52 flows out as the low-pressure gas phase refrigerant. The flow of the refrigerant when the control processing of steps S52 and S53 is performed is in the direction of the arrow in FIG. Since the refrigerant returning from the repeater 30 to the outdoor unit 10 via the bypass pipe 52 merges with the refrigerant returned from the other indoor unit 20, the low-pressure vapor-phase refrigerant is sucked by the compressor 1. It is possible to adjust.

According to this control process, the refrigerant discharged from the compressor 1 is returned to the outdoor unit 10 via the bypass pipe 52 without flowing into the stopped indoor unit 20. Therefore, according to this control process, it is possible to suppress the temperature rise in the air-conditioned space in which the stopped indoor unit 20 is installed, and prevent the refrigerant from staying in the stopped indoor unit 20. Further, in the case of the fourth embodiment, the passing noise of the refrigerant may be intermittently generated in the first decompression device 6, but in the case of the fifth embodiment, since the first decompression device 6 is closed, the refrigerant Passing sound can be suppressed.

Embodiment 6.
The configuration of the air conditioner 100 according to the sixth embodiment will be described with reference to FIGS. 11 to 13. FIG. 11 is a schematic refrigerant circuit diagram showing an example of the refrigerant circuit of the air conditioner 100 according to the sixth embodiment. In the air conditioner 100 according to the sixth embodiment, the first refrigerant pipe 5a and the second refrigerant pipe 5b are provided with a branch pipe 90 having three openings. FIG. 12 is an enlarged view of the branch pipe 90 of FIG. Of the three openings of the branch pipe 90 provided in the first refrigerant pipe 5a, two openings are connected to the first refrigerant pipe 5a by brazing or the like. A cap 92 is attached to the remaining opening of the branch pipe 90 by brazing or the like in order to close the opening. The branch pipe 90 provided in the second refrigerant pipe 5b is also attached in the same manner. FIG. 13 is an enlarged view showing a state in which the flow path switching valve 50 and the bypass pipe 52 are arranged in the refrigerant circuit of the air conditioner 100 according to the sixth embodiment. In the air conditioner 100, the branch pipe 90 provided in the first refrigerant pipe 5a can be removed by melting the brazing or the like, and the flow path switching valve 50 can be attached by brazing or the like. Further, in the air conditioner 100, the cap 92 of the branch pipe 90 provided in the second refrigerant pipe 5b is removed by melting the brazing or the like, and a bypass is provided between the branch pipe 90 and the flow path switching valve 50. The pipe 52 can be attached by brazing or the like. Since the other configurations of the air conditioner 100 are the same as those in the first and second embodiments, the description thereof will be omitted.

As described above, the flow path switching valve 50 and the bypass pipe 52 can be detachably attached to the air conditioner 100. According to this configuration, when noise is generated in the repeater 30, the flow path switching valve 50 and the bypass pipe 52 can be attached later, so that the structure of the repeater 30 can be simplified and the material cost can be reduced. Is possible.

Other embodiments.
The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the gist of the present invention. For example, in the sixth embodiment described above, the bypass pipe 52 may be a bypass pipe 52 provided with the second decompression device 54. Further, the bypass pipe 52 not provided with the second decompression device 54 can be replaced with the bypass pipe 52 provided with the second decompression device 54, and vice versa.

Further, the above-described embodiments can be combined with each other.

1 Compressor, 2 Refrigerant flow path switching device, 3 Heat source side heat exchanger, 4 Load side heat exchanger, 5a 1st refrigerant piping, 5b 2nd refrigerant piping, 6 1st decompression device, 7 Capillary tube, 8 Strainer, 10 outdoor unit, 20 indoor unit, 30 repeater, 50 flow path switching valve, 50a 1st port, 50b 2nd port, 50c 3rd port, 52 bypass piping, 54 2nd decompression device, 70 control device, 72a 1st Temperature sensor, 72b 2nd temperature sensor, 72c 3rd temperature sensor, 74 Refrigerant leakage detection device, 90 branch pipe, 92 cap, 100 air conditioner.

Claims

An outdoor unit having a heat source side heat exchanger and a compressor connected to the heat source side heat exchanger.
Multiple indoor units with load side heat exchangers
It has a first decompression device connected to the heat source side heat exchanger, and includes a repeater connected to a part of the plurality of indoor units.
The repeater
A first refrigerant pipe connected between the compressor and the load side heat exchanger,
A second refrigerant pipe connected between the first decompression device and the heat source side heat exchanger,
The flow path switching valve provided in the first refrigerant pipe and
One end is connected to the flow path switching valve, and the other end is a bypass pipe connected to the second refrigerant pipe.
The flow path switching valve is
A first flow path that communicates the first refrigerant pipe and the bypass pipe on the compressor side,
An internal flow path includes a second flow path for communicating the first refrigerant pipe on the compressor side and the first refrigerant pipe on the load side heat exchanger side.
An air conditioner in which the internal flow path is switched so as to open the internal flow path of either the first flow path or the second flow path and close the other internal flow path.
The air conditioner according to claim 1, further comprising a control device for adjusting the opening degree of the first decompression device and switching the internal flow path of the flow path switching valve.
The control device is
During the defrosting operation in which the high-temperature and high-pressure refrigerant is supplied to the heat source side heat exchanger.
The air conditioner according to claim 2, wherein the first flow path is opened, the second flow path is closed, and the opening degree of the first decompression device is fully closed.
The compressor is a variable capacity compressor, and is
The control device is
During the oil recovery operation in which the lubricating oil discharged by the compressor together with the refrigerant is recovered inside the compressor.
The air conditioner according to claim 2 or 3, wherein the first flow path is opened, the second flow path is closed, and the opening degree of the first decompression device is fully closed.
The indoor unit is
It has a refrigerant leak detection device and
The control device is
When a refrigerant leak is detected by the refrigerant leak detection device,
The air conditioner according to any one of claims 2 to 4, wherein the first flow path is opened, the second flow path is closed, and the opening degree of the first decompression device is fully closed.
The control device is
During the heating operation in which the high-temperature and high-pressure refrigerant is supplied to the heat source side heat exchanger.
When all the indoor units connected to the repeater are stopped and the refrigerant is retained in the indoor unit, the first flow path is opened, the second flow path is closed, and the first flow path is closed. The air conditioner according to any one of claims 2 to 5, wherein the opening degree of the decompression device is fully opened.
The repeater
It has a second decompression device provided in the bypass pipe.
The control device is
During the heating operation in which the high-temperature and high-pressure refrigerant is supplied to the heat source side heat exchanger.
When the indoor unit connected to the repeater is stopped, the first flow path is opened, the second flow path is closed, and the opening degree of the first decompression device is fully closed.
The air conditioner according to any one of claims 2 to 6, wherein the opening degree of the second decompression device is adjusted so that the refrigerant flowing out of the bypass pipe has a lower pressure than the refrigerant flowing into the bypass pipe. ..
The air conditioner according to any one of claims 1 to 7, wherein the flow path switching valve and the bypass pipe are removable.