CN114008393A

CN114008393A - Air conditioner

Info

Publication number: CN114008393A
Application number: CN201980097651.8A
Authority: CN
Inventors: 森下侑哉
Original assignee: Mitsubishi Electric Corp
Current assignee: Mitsubishi Electric Corp
Priority date: 2019-07-01
Filing date: 2019-07-01
Publication date: 2022-02-01
Anticipated expiration: 2039-07-01
Also published as: WO2021001869A1; GB2603246B; GB202115484D0; CN114008393B; GB2603246A

Abstract

The air conditioner is provided with a relay machine having a first decompression device, and the relay machine is provided with: a flow path switching valve provided in a first refrigerant pipe connected between the compressor and the load-side heat exchanger; and a bypass pipe having one end connected to the flow path switching valve and the other end connected to a second refrigerant pipe connected between the first decompression device and the heat source side heat exchanger, wherein the flow path switching valve includes as an internal flow path: the internal flow path is switched such that the internal flow path of one of the first flow path and the second flow path is open and the internal flow path of the other is closed.

Description

Air conditioner

Technical Field

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

Background

Patent document 1 discloses an air conditioner including a relay unit that relays between an outdoor unit and an indoor unit. In the air conditioner of patent document 1, a decompression device is housed in the relay unit. In the air conditioner of patent document 1, a plurality of indoor units are connected to a relay unit, and the plurality of indoor units can be individually switched on and off.

Patent document 1: japanese patent laid-open publication No. 2015-135196

In some air conditioners, the amount of refrigerant circulating is 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 refrigerant circulating in the indoor unit that is being activated, there is a case where the refrigerant is temporarily circulated even in the indoor unit that is being stopped. In this case, in the indoor unit that is stopped, in order to suppress a temperature change in the space in which the indoor unit is installed, the opening degree of the pressure reducing device connected to the indoor unit that is stopped is smaller than the opening degree of the pressure reducing device connected to the indoor unit that is operating, and is adjusted to the minimum opening degree. However, when the opening degree of the pressure reducing device is adjusted in this way, noise is generated when the refrigerant passes through the pressure reducing device, and therefore, there is a possibility that the quietness of the relay device is reduced.

Disclosure of Invention

The present invention has been made to solve the above-described problems, and an object thereof is to provide an air conditioner capable of maintaining the silence of a relay device.

An air conditioner of the present invention includes: an outdoor unit having a heat source side heat exchanger and a compressor connected to the heat source side heat exchanger; a plurality of indoor units having load-side heat exchangers; and a relay device that has a first decompression device connected to the heat source side heat exchanger and is connected to a part of the plurality of indoor units, the relay device including: 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; a flow path switching valve provided in the first refrigerant pipe; and a bypass pipe having one end connected to the flow path switching valve and the other end connected to the second refrigerant pipe, wherein the flow path switching valve includes as an internal flow path: a first flow path that communicates the first refrigerant pipe on the compressor side with the bypass pipe; and a second channel that communicates the first refrigerant pipe on the compressor side with the first refrigerant pipe on the load-side heat exchanger side, wherein the channel switching valve switches the internal channel such that the internal channel of one of the first channel and the second channel is open and the internal channel of the other channel is closed.

In the air conditioning apparatus according to the present invention, since the relay unit includes the flow path switching valve and the bypass pipe, when the indoor unit is stopped, the internal flow path of the flow path switching valve can be switched so that the refrigerant does not flow into the indoor unit, and the refrigerant can be bypassed by the bypass pipe. That is, in the air conditioning apparatus 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 pressure reducing device. Therefore, in the air conditioning apparatus according to the present invention, since the relay unit includes the flow path switching valve and the bypass pipe, the noise of the first pressure reducing device caused by the refrigerant passing therethrough can be suppressed, and thus the air conditioning apparatus capable of maintaining the quietness of the relay unit can be provided.

Drawings

Fig. 1 is a schematic diagram showing an example of an air conditioner according to embodiment 1.

Fig. 2 is a schematic refrigerant circuit diagram showing a part of the air conditioner of fig. 1.

Fig. 3 is a flowchart showing a control process of the flow path switching valve and the first pressure reducer during the defrosting operation in embodiment 1.

Fig. 4 is a flowchart showing a control process of the flow path switching valve and the first pressure reducer in the oil recovery operation according to embodiment 2.

Fig. 5 is a schematic refrigerant circuit diagram showing an example of the refrigerant circuit of the air conditioning apparatus according to embodiment 3.

Fig. 6 is a flowchart showing a control process of the flow path switching valve and the first pressure reducer in the refrigerant leakage detection according to embodiment 3.

Fig. 7 is a schematic refrigerant circuit diagram showing an example of the refrigerant circuit of the air conditioning apparatus according to embodiment 4.

Fig. 8 is a flowchart showing a control process of the flow path switching valve and the first pressure reducer when the indoor unit of embodiment 4 is stopped.

Fig. 9 is a schematic refrigerant circuit diagram showing an example of the refrigerant circuit of the air conditioning apparatus according to embodiment 5.

Fig. 10 is a flowchart showing a control process of the flow path switching valve, the first pressure reducer, and the second pressure reducer in the air conditioner according to embodiment 5 during the heating operation.

Fig. 11 is a schematic refrigerant circuit diagram showing an example of a refrigerant circuit of an air conditioning apparatus according to embodiment 6.

Fig. 12 is an enlarged view of the branch pipe of fig. 11.

Fig. 13 is an enlarged view showing a state in which a flow path switching valve and bypass piping are disposed in a refrigerant circuit of the air conditioning apparatus according to embodiment 6.

Detailed Description

Embodiment 1.

An air conditioning apparatus 100 according to embodiment 1 will be described. Fig. 1 is a schematic diagram showing an example of an air conditioner 100 according to embodiment 1. Fig. 2 is a schematic refrigerant circuit diagram showing a part of the air conditioner 100 of fig. 1. In the following drawings, the relationship between the dimensions and the shapes of the respective components may be different from the actual ones. In the following drawings, the same components or portions or components or portions having the same functions are denoted by the same reference numerals, or the reference numerals are omitted.

As shown in fig. 1, the air conditioner 100 includes an outdoor unit 10, a plurality of indoor units 20, and a relay unit 30. The outdoor unit 10 and the relay unit 30 are connected by a refrigerant pipe. Further, some of the indoor units 20 are connected to the outdoor unit 10 via the relay unit 30, and other of the indoor units 20 are directly connected to the outdoor unit 10 without passing through the relay unit 30. For example, the relay unit 30 is connected to the indoor unit 20 installed in a space where silence is required, for example, a hotel room, a conference room, or an office. In addition, a space not requiring silence, for example, an indoor unit 20 such as an elevator car or a warehouse is directly connected to the outdoor unit 10 without passing through the relay unit 30. In fig. 1, the outdoor unit 10 and the relay unit 30 are only one unit, but a plurality of units may be provided. The number of indoor units 20 connected to the relay unit 30 may be one. The refrigerant pipe may be a refrigerant pipe originally installed in an object 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 in which a low-temperature low-pressure two-phase refrigerant is caused to flow into the indoor unit 20. The "heating operation" refers to an operation mode of the air conditioning apparatus 100 in which high-temperature, high-pressure gas-phase refrigerant is caused to flow into the indoor unit 20.

The outdoor unit 10 includes a compressor 1, a refrigerant flow 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 refrigerant pipes via the refrigerant flow switching device 2.

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

The refrigerant flow switching device 2 is an electrical device that switches the refrigerant flow path inside the refrigerant flow switching device 2 by an electrical signal in response to switching from the cooling operation to the heating operation of the air conditioning apparatus 100 or from the heating operation to the cooling operation of the air conditioning apparatus 100. In fig. 2, the refrigerant flow paths inside the refrigerant flow switching device 2 during the cooling operation are shown by broken lines, and the refrigerant flow paths inside the refrigerant flow switching device 2 during the heating operation are shown by solid lines. As the refrigerant flow switching device 2, for example, a four-way valve to which an operation of a solenoid valve is applied is used. The refrigerant flow switching device 2 may be a switching device in which a two-way valve or a three-way valve is combined. In the air conditioning apparatus 100, the refrigerant flow switching device 2 can be omitted when only one of the cooling operation and the heating operation is performed.

The heat source side heat exchanger 3 is a heat transfer device that moves and exchanges thermal energy between two fluids having different thermal energies. The heat source side heat exchanger 3 functions as a condenser during the cooling operation and functions 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-and-fin heat exchanger, or a water-cooled heat exchanger such as a shell-and-tube heat exchanger, a plate heat exchanger, or a double-tube heat exchanger is used. In the air conditioner 100, the condenser is sometimes called a radiator.

The indoor unit 20 includes 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, as in the heat source-side heat exchanger 3 described above. The load side heat exchanger 4 functions as an evaporator during the cooling operation and functions 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-and-fin heat exchanger is used.

The relay unit 30 is connected between the outdoor unit 10 and the indoor units 20 by refrigerant pipes. The relay device 30 includes: a first refrigerant pipe 5a, which is one of the refrigerant pipes connecting the compressor 1 and the load-side heat exchanger 4, and a second refrigerant pipe 5b, which is a part of the refrigerant pipe connecting the heat source-side heat exchanger 3. 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. The relay unit 30 includes a first pressure reducer 6, a capillary tube 7, and a filter 8.

The first decompression device 6 is an expansion device that expands and decompresses a high-pressure liquid-phase refrigerant. As the first decompressing 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 using a diaphragm for a pressure receiving portion. The automatic expansion valve of the temperature type is an expansion device that adjusts the amount of refrigerant in accordance with the degree of superheat of the gas-phase refrigerant on the suction side of the compressor 1. A linear electronic expansion valve is an expansion device, also referred to simply as an LEV, capable of adjusting the opening degree in multiple stages or continuously. The first pressure reducer 6 is disposed in each branch refrigerant pipe connected to the second refrigerant pipe 5 b.

The capillary tube 7 is a capillary tube-shaped refrigerant tube configured by a long and thin copper tube, and configured to pass a required amount of refrigerant according to a tube resistance and decompress the refrigerant. The capillary tube 7 is connected to each branch refrigerant pipe connected to the second refrigerant pipe 5b so as to be connected in series to the first decompressor 6. The capillary tube 7 is disposed in the branch refrigerant pipe on the indoor unit 20 side of the first pressure reducer 6. In the air conditioner 100, the capillary tube 7 is a member that assists the decompression function of the first decompressor 6, and can be omitted.

The filter 8 is a filter for filtering out dust, impurities, and the like contained in the refrigerant such as sludge generated during the operation of the compressor 1. The filter 8 is provided to prevent clogging of the first pressure reducing device 6 and the capillary 7. The filter 8 is provided on the second refrigerant pipe 5b and each of the branch refrigerant pipes connected to the second refrigerant pipe 5b, and is provided on both sides of the refrigerant pipe on which the first pressure reducer 6 and the capillary tube 7 are disposed. For example, if the compressor 1 can suppress the generation of sludge, the filter 8 can be omitted.

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

In the air conditioning apparatus 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 pipes to form a refrigerant circuit in which a 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 switching device 2 performs path control of the refrigerant flow in the refrigerant flow switching device 2, as indicated by the broken line in fig. 2.

In the outdoor unit 10, a high-temperature and high-pressure gas-phase refrigerant discharged from the compressor 1 flows into the heat source side heat exchanger 3 through 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 flowing into the heat source side heat exchanger 3 passes through the heat source side heat exchanger 3 to exchange heat with a heat medium such as outside air, 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 of the outdoor unit 10 and flows into the relay unit 30.

The high-pressure liquid-phase refrigerant flowing into the relay unit 30 flows into the first pressure reducer 6 through the second refrigerant pipe 5 b. The high-pressure gas-phase refrigerant flowing into the first pressure reducer 6 is expanded and reduced in pressure by the first pressure reducer 6, and flows out of the first pressure reducer 6 as a low-temperature low-pressure two-phase refrigerant. The low-temperature low-pressure two-phase refrigerant flowing out of the first pressure reducer 6 flows out of the relay unit 30 and flows into the indoor unit 20.

The low-temperature low-pressure two-phase refrigerant flowing into the indoor unit 20 flows into the load side heat exchanger 4. The load side heat exchanger 4 functions as an evaporator during the cooling operation. The low-pressure two-phase refrigerant flowing into the load-side heat exchanger 4 passes through the load-side heat exchanger 4 to exchange heat with a heat medium such as indoor air, 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, high-dryness two-phase refrigerant. The low-pressure gas-phase refrigerant flowing out of the load-side heat exchanger 4 flows out of the indoor unit 20, and flows into the outdoor unit 10 via the first refrigerant pipe 5a of the relay unit 30.

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

An outline of the operation of the refrigerant circuit of the air-conditioning apparatus 100 during the heating operation will be described. During the heating operation, the refrigerant flow switching device 2 performs path control of the refrigerant flow inside the refrigerant flow switching device 2 as shown by the solid line in fig. 2.

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

The high-temperature and high-pressure gas-phase refrigerant flowing into the indoor unit 20 flows into the load-side heat exchanger 4. The load side heat exchanger 4 functions as a condenser during the heating operation. The high-temperature and high-pressure gas-phase refrigerant flowing into the load-side heat exchanger 4 passes through the load-side heat exchanger 4 to exchange heat with a heat medium such as indoor air, 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 relay unit 30.

The high-pressure liquid-phase refrigerant flowing into the relay unit 30 flows into the first pressure reducer 6. The high-pressure liquid-phase refrigerant flowing into the first pressure reducer 6 is expanded and reduced in pressure by the first pressure reducer 6, and flows out of the first pressure reducer 6 as a low-temperature low-pressure two-phase refrigerant. The low-temperature low-pressure two-phase refrigerant flowing out of the first pressure reducer 6 flows out of the relay unit 30 through the second refrigerant pipe 5b and flows into the outdoor unit 10.

The low-temperature low-pressure two-phase refrigerant flowing 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 exchanges heat with a heat medium such as outside air in 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, high-dryness two-phase refrigerant.

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

Next, a bypass circuit of the relay unit 30 will be explained. The relay unit 30 includes a bypass circuit formed by a flow path switching valve 50 and a bypass pipe 52.

The flow path switching valve 50 is an electrical device that is provided in the middle of the first refrigerant pipe 5a and switches the refrigerant circuit and the bypass circuit by an electrical signal. The flow path switching valve 50 includes: 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 third port 50c connected to one end of the bypass pipe 52. The flow path switching valve 50 includes, as internal flow paths: a first flow path communicating between the first port 50a and the third port 50c, and a second flow path communicating between the first port 50a and the second port 50 b. 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 paths between the first refrigerant pipe 5a on the outdoor unit 10 side and the bypass pipe 52 are communicated with each other. In the flow path switching valve 50, the first flow path is closed and the second flow path is opened, so that the refrigerant flow paths between the first refrigerant pipe 5a on the outdoor unit 10 side and the first refrigerant pipe 5a on the indoor unit 20 side communicate with each other. As the flow path switching valve 50, for example, a three-way valve to which the operation of an electromagnetic valve is applied is used. The flow path switching valve 50 may be an electrical device in which one port of the four-way valve is closed, or may be an electrical device in which two-way valves are combined.

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 5 b. The relay unit 30 includes only small electrical devices such as the first decompressing device 6, and the relay unit 30 can be easily reduced in size as compared with the outdoor unit 10 or the indoor unit 20. Therefore, the bypass pipe 52 can be designed to have a short length by setting the distance between the first refrigerant pipe 5a and the second refrigerant pipe 5b housed inside the relay unit 30 to be short.

By providing the flow path switching valve 50 and the bypass pipe 52, the relay unit 30 can open the first flow path of the flow path switching valve 50 and close the second flow path when all the indoor units 20 are stopped, thereby bypassing the refrigerant through the bypass pipe 52. That is, according to this configuration, when all the indoor units 20 are stopped, since the flow paths can be switched so that the refrigerant does not pass through the first decompressing device 6, noise of the first decompressing device 6 due to the passage of the refrigerant can be suppressed, and thus the air conditioner 100 capable of maintaining the quietness of the relay unit 30 can be provided.

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

The control device 70 is configured as a microcomputer or a microprocessor unit provided 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 electrical box of the outdoor unit 10. The control device 70 is connected to the first temperature sensor 72a, the compressor 1, the refrigerant flow switching device 2, the first pressure reducing device 6, and the flow switching valve 50 by wire or wireless. In the air conditioning apparatus 100, the control device 70 may be provided only in any one of the outdoor unit 10, the indoor units 20, and the relay unit 30. 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 relay unit 30, and may perform wired or wireless communication in a bidirectional manner with each other. In the following drawings including fig. 2, a communication line wired or wirelessly connected to the control device 70 is not shown.

The control device 70 transmits a control signal for switching the internal flow path of the flow path switching valve 50 to the flow path switching valve 50 so that the internal flow path of either the first flow path or the second flow path of the flow path switching valve 50 is opened and the other flow path is closed. Further, the control device 70 transmits a control signal for adjusting the opening degree of the first decompressing device 6 to the first decompressing device 6. Further, the control device 70 includes all circuits for transmitting signals for adjusting the opening degree of the first decompressing device 6 and switching the internal flow path of the flow path switching valve 50.

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

The control device 70 may be configured to perform frequency control of the compressor 1, internal flow path control of the refrigerant flow path switching device 2 when switching between the cooling operation and the heating operation, or start and stop of the air conditioner 100.

Fig. 3 is a flowchart showing a control process of the flow path switching valve 50 and the first pressure reducer 6 during the defrosting operation in embodiment 1. Here, the "defrosting operation" refers to an operation mode in which the high-temperature and high-pressure refrigerant is supplied to the heat source-side heat exchanger 3 in order to suppress frost formation in the heat source-side heat exchanger 3, and is mainly performed before the heating operation is started or during the heating operation. The defrosting operation is performed by, for example, switching the internal flow path of the refrigerant flow switching device 2 to the internal flow path during the cooling operation in the heating operation. 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 through the bypass circuit without switching the refrigerant flow switching device 2. The control processing in fig. 3 can be set to be performed at regular intervals, for example, at intervals of 30 minutes. In the normal heating operation before the control process, the internal channel of the channel switching valve 50 is in a state where the first channel is closed and the second channel is open.

In step S11, the control device 70 determines whether or not the air conditioner 100 is performing 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 is ended.

If it is determined in step S11 that the defrosting operation is to be performed, in step S12, the controller 70 performs the following control: the first channel of the channel switching valve 50 is opened, the second channel of the channel switching valve 50 is closed, and the opening degree of the first pressure reducer 6 is fully closed. In fig. 2, the flow of the refrigerant when the control process of step S12 is performed is shown by an arrow. At this time, since the high-temperature gas-phase refrigerant does not flow through the indoor unit 20 in the normal operation, for example, the load-side heat exchanger 4 performs the heating operation of blowing only. The high-pressure liquid-phase refrigerant is returned from the relay unit 30 to the outdoor unit 10 via the bypass pipe 52, but the refrigerant can be adjusted to be a low-pressure gas-phase refrigerant sucked into the compressor 1 because the refrigerant merges with the refrigerant returned from the other indoor units 20.

When the air conditioner 100 performs the defrosting operation, the amount of refrigerant discharged from the compressor 1 temporarily increases and the amount of refrigerant flowing into the relay unit 30 to which the stopped indoor unit 20 is connected also increases as compared to when the air conditioner is performing the heating operation. However, according to this control process, the refrigerant discharged from the compressor 1 and flowing into the heat source side heat exchanger 3 returns to the outdoor unit 10 via the bypass pipe 52, and therefore, it is not necessary to open the first decompressing device 6 with an increase in the amount of refrigerant flowing. Therefore, according to this control process, since noise of the first decompression device 6 due to the passage of the refrigerant can be suppressed, the air conditioner 100 capable of maintaining the quietness of the relay unit 30 can be provided.

In addition, according to this control process, since it is not necessary to open the first decompressing device 6 with an increase in the inflow amount of the refrigerant, the refrigerant does not flow to the indoor unit 20 that is stopped. Therefore, the temperature of the air-conditioned space in which the stopped indoor unit 20 is installed can be prevented from decreasing, and the comfort of the air-conditioned space can be maintained.

When a plurality of relay devices 30 are connected to the air conditioner 100, the control device 70 can perform the control process of step S12 by using the relay device 30 having the smallest total operating capacity of the connected indoor units 20. Further, the control device 70 may be configured to: during the control processing of steps S11 and S12, it is determined whether or not the relay device 30 satisfies the stop enabling condition, and the control processing of step S12 is performed by the relay device 30 that satisfies a part of the stop enabling condition. The stop enabling condition may be determined based on, for example, a threshold value of the operating capacity of the indoor unit 20 connected to the relay unit 30. For example, the control device 70 is configured to: when all the indoor units 20 connected to the relay unit 30 are stopped, it may be determined that the stop enabling condition is satisfied.

Embodiment 2.

In embodiment 2, a control process of the flow path switching valve 50 and the first pressure reducer 6 during the oil recovery operation will be described with reference to fig. 4. Fig. 4 is a flowchart showing a control process of the flow path switching valve 50 and the first pressure reducer 6 during the oil recovery operation according to embodiment 2. The configuration of the air conditioner 100 is the same as that of embodiment 1, and therefore, the description thereof is omitted.

Here, the "oil recovery operation" refers to an operation mode of the air conditioning apparatus 100 in which the compressor 1 recovers the lubricating oil discharged together with the refrigerant into the compressor 1. When the cooling operation is performed for a long time and at a low load, the lubricating oil discharged from the compressor 1 together with the refrigerant is retained in the refrigerant piping connecting the outdoor unit 10 and the relay unit 30, particularly in the so-called liquid-side piping disposed between the heat source-side heat exchanger 3 and the first decompressing device 6. This is because the flow velocity of the liquid-phase refrigerant flowing through the liquid-side pipe is slower than that of the gas-phase refrigerant, and the liquid lubricating oil contained in the liquid-phase refrigerant is more likely to be deposited in the refrigerant pipe than the gas lubricating oil contained in the gas-phase refrigerant. The oil recovery operation is performed to recover the lubricating oil accumulated outside the compressor 1 by increasing the operating frequency of the compressor 1 as compared with the normal cooling operation. The control processing of fig. 4 can be set to be performed in a case where the operation is performed for a long time, for example, for 5 hours or more, at a lower frequency than the normal operation. During the normal cooling operation before this 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, control device 70 determines whether or not the oil recovery operation is performed by air conditioner 100. Whether or not to perform the oil recovery operation is determined based on a determination criterion predetermined based on the load of the entire air conditioner 100 and the operation time under the load, for example. When it is determined that the oil recovery operation is not performed, the control process is ended.

When it is determined in step S21 that the oil recovery operation is to be performed, in step S22, the controller 70 performs the following control: the first channel of the channel switching valve 50 is opened, the second channel of the channel switching valve 50 is closed, and the opening degree of the first pressure reducer 6 is 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 embodiment 1. At this time, since the low-temperature low-pressure two-phase refrigerant does not flow through the indoor unit 20 in the normal operation, for example, the load-side heat exchanger 4 performs the heating operation of blowing only. The high-pressure liquid-phase refrigerant is returned from the relay unit 30 to the outdoor unit 10 via the bypass pipe 52, but the refrigerant merges with the refrigerant returned from the other indoor units 20, and therefore can be adjusted to be a low-pressure gas-phase refrigerant that is sucked into the compressor 1.

When the oil recovery operation is performed by the air conditioner 100, the operation frequency of the compressor 1 is increased, and therefore, the amount of refrigerant discharged from the compressor 1 temporarily increases and the amount of refrigerant flowing into the relay unit 30 to which the stopped indoor unit 20 is connected also increases compared to the normal cooling operation. However, according to this control process, the refrigerant discharged from the compressor 1 and flowing into the heat source side heat exchanger 3 returns to the outdoor unit 10 via the bypass pipe 52, and therefore, it is not necessary to open the first decompressing device 6 with an increase in the amount of refrigerant flowing. Therefore, according to this control process, noise of the first decompression device 6 due to the passage of the refrigerant can be suppressed, and therefore the air conditioning apparatus 100 capable of maintaining the quietness of the relay unit 30 can be provided.

In addition, according to this control process, since it is not necessary to open the first decompressing device 6 with an increase in the inflow amount of the refrigerant, the refrigerant does not flow to the indoor unit 20 that is stopped. Therefore, a temperature drop in the air-conditioned space in which the stopped indoor unit 20 is provided can be prevented, and thus the comfort of the air-conditioned space can be maintained.

When a plurality of the relay devices 30 are connected to the air-conditioning apparatus 100, the control device 70 can perform the control process of step S22 by using the relay device 30 having the smallest total operating capacity of the connected indoor units 20. Further, the controller 70 may be configured to determine whether or not the relay device 30 satisfies the stop enabling condition during the control processing of steps S21 and S22, and perform the control processing of step S22 by the relay device 30 satisfying a part of the stop enabling condition. The stop enabling condition may be determined based on, for example, a threshold value of the operating capacity of the indoor unit 20 connected to the relay unit 30. For example, the control device 70 is configured to: when all the indoor units 20 connected to the relay unit 30 are stopped, it may be determined that the stop enabling condition is satisfied.

Embodiment 3.

The configuration of the air conditioner 100 according to embodiment 3 will be described with reference to fig. 5. Fig. 5 is a schematic refrigerant circuit diagram showing an example of the refrigerant circuit of the air-conditioning apparatus 100 according to embodiment 3. In the air conditioning apparatus 100 according to embodiment 3, the indoor unit 20 is provided with the refrigerant leakage detection device 74. The control device 70 receives detection information of leakage of refrigerant from the refrigerant leakage detecting device 74. As the refrigerant leakage detecting device 74, for example, a refrigerant leakage detecting sensor is provided. As the refrigerant leak detection sensor, for example, a gas sensor such as a semiconductor type gas sensor, a hot-wire type semiconductor type gas sensor, or an infrared type gas sensor is used. The refrigerant leak detection sensor may be an oxygen concentration type gas sensor that detects a decrease in oxygen concentration, or may be a combustible gas detection type gas sensor that detects a combustible gas. The refrigerant leak detector 74 may be provided in an information input device to the indoor unit 20, for example, a remote controller. The refrigerant leakage detection device 74 is not limited to the refrigerant leakage detection sensor, and may be a device that indirectly detects leakage of refrigerant in response to an abnormality in the temperature of the refrigerant pipe of the indoor unit 20, for example. Since other configurations of the air conditioner 100 are the same as those of embodiments 1 and 2, descriptions thereof are omitted.

Fig. 6 is a flowchart showing a control process of the flow path switching valve 50 and the first pressure reducer 6 in the refrigerant leakage detection according to embodiment 3. The control processing of fig. 6 can be set to be performed at regular intervals, for example, at every 5 minutes. In the normal cooling operation or the 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 opened.

In step S31, the control device 70 determines whether or not refrigerant leakage is detected in the indoor unit 20. If it is determined that the refrigerant leakage is not detected, the control process is ended. When it is determined in step S31 that refrigerant leakage has been detected in the indoor unit 20, the control device 70 performs the following control in step S32: the first channel of the channel switching valve 50 is opened, the second channel of the channel switching valve 50 is closed, and the opening degree of the first pressure reducer 6 is fully closed. The flow of the refrigerant when the control processing of step S32 is performed is in the direction of the broken line arrow in fig. 5 in the case of the cooling operation, and in the direction of the solid line arrow in fig. 5 in the case of the heating operation. The refrigerant returned from the relay unit 30 to the outdoor unit 10 via the bypass pipe 52 can be adjusted to be a low-pressure gas-phase refrigerant sucked into the compressor 1 because the refrigerant merges with the refrigerant returned from the other indoor units 20.

According to this control process, the refrigerant discharged from the compressor 1 returns to the outdoor unit 10 via the bypass pipe 52 without flowing into the indoor unit 20, and therefore, leakage of the refrigerant from the indoor unit 20 can be suppressed.

Embodiment 4.

The configuration of the air conditioner 100 according to embodiment 4 will be described with reference to fig. 7. Fig. 7 is a schematic refrigerant circuit diagram showing an example of the refrigerant circuit of the air-conditioning apparatus 100 according to embodiment 4. In the air conditioning apparatus 100 according to embodiment 4, the indoor unit 20 is provided with the second temperature sensor 72b and the third temperature sensor 72 c. The second temperature sensor 72b is a sensor that measures the temperature of the air after heat exchange in 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-phase refrigerant or the two-phase refrigerant during the heating operation, and functions as a supercooling temperature sensor. The control device 70 receives detection information of leakage of the refrigerant from the second temperature sensor 72b and the third temperature sensor 72 c. As the second temperature sensor 72b and the third temperature sensor 72c, for example, sensors including a semiconductor material such as a thermistor, a metal material such as a temperature measuring resistor, or the like are used. Since other configurations of the air conditioner 100 are the same as those of embodiments 1 and 2, descriptions thereof are omitted. In the air conditioning apparatus 100, one of the second temperature sensor 72b and the third temperature sensor 72c may be omitted.

Fig. 8 is a flowchart showing the control process of the flow path switching valve 50 and the first pressure reducer 6 when the indoor unit 20 of embodiment 4 is stopped. The control process in fig. 8 can be set to be performed at regular intervals, for example, at intervals of 30 minutes during the heating operation of the air-conditioning apparatus 100. 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 opened.

In step S41, the control device 70 determines whether or not the refrigerant is retained in the indoor unit 20. For example, when the state in which the temperature detected by the second temperature sensor 72b is 30 ℃ continues for 3 minutes, it is determined that the refrigerant is retained in the heat source-side heat exchanger 3 in a two-phase refrigerant state. Alternatively, when the state in which the detected temperature of the third temperature sensor 72c has become constant after the rise continues for 3 minutes, it is determined that the refrigerant has stagnated in the heat source-side heat exchanger 3 in a state of a two-phase refrigerant. If it is determined that the refrigerant is not retained, the control process is terminated.

When it is determined in step S41 that refrigerant is retained in the indoor unit 20, the control device 70 performs the following control in step S42; the first channel of the channel switching valve 50 is opened, the second channel of the channel switching valve 50 is closed, and the opening degree of the first pressure reducer 6 is 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. 7. The refrigerant returned from the relay unit 30 to the outdoor unit 10 via the bypass pipe 52 can be adjusted to be a low-pressure gas-phase refrigerant sucked into the compressor 1 because the refrigerant merges with the refrigerant returned from the other indoor units 20.

According to this control process, the refrigerant discharged from the compressor 1 returns to the outdoor unit 10 through the bypass pipe 52 without flowing into the indoor unit 20. Therefore, according to this control process, it is possible to suppress a temperature increase in the air-conditioned space in which the stopped indoor unit 20 is installed. The refrigerant retained in the indoor units 20 can be returned to the outdoor unit 10 by being guided by the flow of the refrigerant returned to the outdoor unit 10 through the bypass pipe 52. Therefore, it is possible to suppress a decrease in the amount of refrigerant in the indoor units 20 due to the stagnation of refrigerant in the indoor units 20, and it is possible to secure the amount of refrigerant necessary for restarting the heating operation of the indoor units 20.

Embodiment 5.

The configuration of the air conditioner 100 according to embodiment 5 will be described with reference to fig. 9. Fig. 9 is a schematic refrigerant circuit diagram showing an example of the refrigerant circuit of the air-conditioning apparatus 100 according to embodiment 5. In the air conditioning apparatus 100 according to embodiment 5, the second pressure reducer 54 is provided in the bypass pipe 52. The second decompression device 54 is an expansion device that expands and decompresses the high-pressure refrigerant. As the second decompressing device 54, a linear electronic expansion valve or the like is used. Since other configurations of the air conditioner 100 are the same as those of embodiments 1 and 2, descriptions thereof are omitted.

Fig. 10 is a flowchart showing a control process of the flow path switching valve 50, the first pressure reducer 6, and the second pressure reducer 54 during the heating operation of the air conditioner 100 according to embodiment 5. The control process in fig. 10 can be set to be performed at regular intervals, for example, at intervals of 30 minutes during the heating operation of the air-conditioning apparatus 100. 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 opened.

In step S51, the control device 70 determines whether or not the indoor unit 20 connected to the relay unit 30 is stopped. If it is determined that the indoor unit 20 is not stopped, the control process ends. If it is determined in step S51 that the indoor unit 20 is stopped, the controller 70 performs control in step S52 such that: the first channel of the channel switching valve 50 is opened, the second channel of the channel switching valve 50 is closed, and the opening degree of the first pressure reducer 6 is fully closed. In step S53, the controller 70 adjusts the opening degree of the second decompressor 54 so that the high-pressure gas-phase refrigerant flowing into the bypass pipe 52 flows out as a low-pressure gas-phase refrigerant. The flow of the refrigerant when the control processing of step S52 and step S53 is performed is in the direction of the arrow in fig. 9. The refrigerant returned from the relay unit 30 to the outdoor unit 10 via the bypass pipe 52 can be adjusted to be a low-pressure gas-phase refrigerant sucked into the compressor 1 because the refrigerant merges with the refrigerant returned from the other indoor units 20.

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 that is stopped. Therefore, according to this control process, it is possible to suppress a temperature increase in the air-conditioned space in which the stopped indoor unit 20 is installed, and to avoid stagnation of the refrigerant in the stopped indoor unit 20. In embodiment 4, the refrigerant passing sound may be intermittently generated in the first pressure reducing device 6, but in embodiment 5, the refrigerant passing sound can be suppressed because the first pressure reducing device 6 is closed.

Embodiment 6.

The configuration of an air conditioning apparatus 100 according to embodiment 6 will be described with reference to fig. 11 to 13. Fig. 11 is a schematic refrigerant circuit diagram showing an example of the refrigerant circuit of the air-conditioning apparatus 100 according to embodiment 6. In the air conditioning apparatus 100 according to embodiment 6, the first refrigerant pipe 5a and the second refrigerant pipe 5b are provided with branch pipes 90 having three openings. Fig. 12 is an enlarged view of the branch pipe 90 of fig. 11. Two of the three openings of the branch pipe 90 provided in the first refrigerant pipe 5a 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 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 disposed in the refrigerant circuit of the air-conditioning apparatus 100 according to embodiment 6. In the air conditioning apparatus 100, the branch pipe 90 provided in the first refrigerant pipe 5a can be removed by melting brazing or the like, and the flow path switching valve 50 can be attached by brazing or the like. In the air conditioning apparatus 100, the cap 92 of the branch pipe 90 provided in the second refrigerant pipe 5b can be removed by melting brazing or the like, and the bypass pipe 52 can be attached between the branch pipe 90 and the flow path switching valve 50 by brazing or the like. Since other configurations of the air conditioner 100 are the same as those of embodiments 1 and 2, descriptions thereof are omitted.

As described above, the flow path switching valve 50 and the bypass pipe 52 are detachably attached to the air conditioner 100. According to this configuration, when noise is generated in the relay unit 30, the flow path switching valve 50 and the bypass pipe 52 can be attached at a later stage, and therefore the structure of the relay unit 30 can be simplified and material costs can be reduced.

Other embodiments are also provided.

The present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the present invention. For example, in embodiment 6 described above, the bypass pipe 52 may be the bypass pipe 52 provided with the second pressure reducer 54. Further, the bypass pipe 52 not provided with the second pressure reducing device 54 may be substituted for the bypass pipe 52 provided with the second pressure reducing device 54, and the reverse may be also possible.

In addition, the above embodiments can be combined separately.

Description of the reference numerals

1 … compressor; 2 … refrigerant flow switching device; 3 … heat source side heat exchanger; 4 … load side heat exchanger; 5a … a first refrigerant pipe; 5b … second refrigerant pipe; 6 … a first pressure reduction device; 7 … capillary tube; 8 … filter; 10 … outdoor unit; 20 … indoor unit; 30 … repeaters; 50 … flow path switching valve; 50a … first port; 50b … second port; 50c … third port; 52 … bypass the piping; 54 … a second pressure relief device; 70 … control device; 72a … first temperature sensor; 72b … second temperature sensor; 72c … third temperature sensor; 74 … refrigerant leak detection device; 90 … branch pipes; 92 … cap; 100 … air conditioning unit.

Claims

1. An air conditioning apparatus is characterized by comprising:

an outdoor unit having a heat source side heat exchanger and a compressor connected to the heat source side heat exchanger;

a plurality of indoor units having load-side heat exchangers; and

a relay unit having a first decompressing device connected to the heat source side heat exchanger and connected to a part of the plurality of indoor units,

the relay device includes:

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;

a flow path switching valve provided in the first refrigerant pipe; and

a bypass pipe having one end connected to the flow path switching valve and the other end connected to the second refrigerant pipe,

the flow path switching valve includes, as an internal flow path:

a first flow path that communicates the first refrigerant pipe on the compressor side with the bypass pipe; and

a second channel that communicates the first refrigerant pipe on the compressor side with the first refrigerant pipe on the load-side heat exchanger side,

the flow path switching valve switches the internal flow path so that one of the first flow path and the second flow path is open and the other is closed.

2. The air conditioner according to claim 1,

the control device adjusts the opening degree of the first pressure reducing device and switches the internal flow path of the flow path switching valve.

3. Air conditioning unit according to claim 2,

the control device opens the first flow path, closes the second flow path, and fully closes the opening of the first decompressing device during a defrosting operation in which a high-temperature and high-pressure refrigerant is supplied to the heat source side heat exchanger.

4. Air conditioning unit according to claim 2 or 3,

the compressor is a variable displacement compressor,

the control device opens the first flow passage, closes the second flow passage, and fully closes the opening of the first pressure reducing device during an oil recovery operation in which the compressor recovers lubricating oil discharged together with a refrigerant into the compressor.

5. An air conditioning apparatus according to any one of claims 2 to 4,

the indoor unit is provided with a refrigerant leakage detection device,

the control device opens the first flow path, closes the second flow path, and fully closes the opening of the first pressure reducing device when the refrigerant leakage detecting device detects the leakage of the refrigerant.

6. An air conditioning apparatus according to any one of claims 2 to 5,

in a heating operation in which a high-temperature and high-pressure refrigerant is supplied to the heat source side heat exchanger, the control device opens the first flow path, closes the second flow path, and fully opens the opening degree of the first pressure reducing device when all of the indoor units connected to the relay unit are stopped and the refrigerant is accumulated in the indoor units.

7. An air conditioning apparatus according to any one of claims 2 to 6,

the relay unit includes a second pressure reducing device provided in the bypass pipe,

the control device opens the first flow path, closes the second flow path, and fully closes the opening of the first pressure reducing device during a heating operation in which a high-temperature and high-pressure refrigerant is supplied to the heat source side heat exchanger, and adjusts the opening of the second pressure reducing device such that the refrigerant flowing out of the bypass pipe becomes lower in pressure than the refrigerant flowing into the bypass pipe, when the indoor unit connected to the relay unit is stopped.

8. An air conditioning apparatus according to any one of claims 1 to 7,

the flow path switching valve and the bypass pipe are detachable.