Air conditioning system and method for vacuuming an air conditioning system

Abstract

This air conditioner capable of simultaneous cooling and heating has an outdoor unit, a plurality of indoor units, and a relay unit. The relay unit comprises: a first path that is configured from first piping and causes a refrigerant to flow from the plurality of indoor units to the relay unit; a second path that is configured from second piping and causes the refrigerant to flow from the relay unit to the plurality of indoor units; a third path that is configured from third piping and causes the refrigerant to flow from the plurality of indoor units to the relay unit; and a fourth path that is configured from fourth piping and causes the refrigerant to flow from the relay unit to the plurality of indoor units. The relay unit comprises: a first opening / closing device that is provided in the first path and individually blocks or circulates the refrigerant flowing from each of the plurality of indoor units to the relay unit; and a second opening / closing device that is provided in the second path and individually blocks or circulates the refrigerant that branches and flows from the relay unit to each of the plurality of indoor units. The relay unit comprises: a first blocking device that opens in a non-energized state and allows the circulation of the refrigerant in the fourth path, and closes in an energized state and blocks the circulation of the refrigerant in the fourth path; and an opening / closing unit for evacuation that opens in a non-energized state and allows the circulation of a fluid in at least one path of the first to fourth paths, and closes in the energized state and blocks the flow of the refrigerant in at least one path.

Description

Technical Field

[0001] The present disclosure provides an air conditioner capable of simultaneous heating and cooling operation and a vacuum drawing method in an air conditioner.

Background Art

[0002] In an air conditioner, for example, a refrigerant circuit is configured by connecting pipes between an outdoor unit, which is a heat source machine arranged outside a building, and an indoor unit arranged inside the building, and a refrigerant is circulated. Then, the air conditioner heats the air by utilizing the heat radiation of the refrigerant or cools the air by utilizing the heat absorption of the refrigerant, thereby performing heating or cooling of the air-conditioned target space.

[0003] When installing an air conditioner, generally, the outdoor unit is filled with refrigerant, and the indoor unit and the relay unit are not filled with refrigerant. When installing an air conditioner, in order to prevent the mixture of air into the refrigerant circuit, construction is carried out in the order of pipe connection, vacuum drawing, opening of the operation valve of the outdoor unit, and additional filling of refrigerant. Here, vacuum drawing is an operation of discharging the air in the pipes constituting the refrigerant circuit using a vacuum pump. From the viewpoint of ease of operation, the vacuum pump is connected to the service port near the operation valve provided on the outdoor unit to suck air. When installing an air conditioner, vacuum drawing is performed from the service port provided on the outdoor unit. Therefore, in an air conditioner, from the viewpoint of workability, it is required to secure a path through which vacuum drawing can be performed from the outdoor unit side to the relay unit and the indoor unit.

[0004] Further, a conventional air conditioner includes a shut-off device that shuts off the flow of refrigerant in the refrigerant circuit in case of refrigerant leakage from the viewpoint of safety (see, for example, Patent Document 1). The shut-off device of Patent Document 1 shuts off the flow of refrigerant in the direction from the outdoor unit to the indoor unit to prevent the refrigerant from staying in the indoor space.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

[0006] Incidentally, power to the air conditioning system is only supplied after all electrical circuits and refrigerant piping have been installed and preparations for trial operation are complete. Therefore, during the vacuuming process performed during the refrigerant piping installation, all components of the refrigerant circuit are de-energized.

[0007] The air conditioning system described in Patent Document 1 is configured with a valve that closes when the shut-off device is not energized. As a result, in the air conditioning system described in Patent Document 1, the refrigerant circuit is shut off at the location where the shut-off device is installed during vacuuming, making it impossible to secure a vacuuming path from the outdoor unit side, which results in poor workability.

[0008] The air conditioning system described in Patent Document 1 has a simple configuration with one indoor unit, but there are also air conditioning systems that have multiple indoor units and are capable of simultaneous cooling and heating. An air conditioning system capable of simultaneous cooling and heating includes an outdoor unit, multiple indoor units, and a relay unit that has multiple valves and distributes the refrigerant to multiple flow paths. Because the relay unit in an air conditioning system capable of simultaneous cooling and heating has multiple valves, if it is configured to have a shut-off function in case of refrigerant leakage, it becomes more difficult to secure a vacuum path, and the problem of ease of installation becomes more pronounced.

[0009] This disclosure has been made in view of these points, and aims to provide an air conditioning system and a vacuuming method for an air conditioning system that can operate simultaneously in heating and cooling mode, have a shut-off function in case of refrigerant leakage, and improve ease of installation. [Means for solving the problem]

[0010] The air conditioning system according to this disclosure is an air conditioning system capable of simultaneous cooling and heating operation, comprising an outdoor unit having a compressor, an outdoor heat exchanger for exchanging heat between outside air and refrigerant, and a flow path switching device; a plurality of indoor units having indoor heat exchangers for exchanging heat between the air to be air-conditioned and refrigerant; and a relay unit located between the outdoor unit and the plurality of indoor units that switches the flow of refrigerant supplied from the outdoor unit to the plurality of indoor units, all connected by refrigerant piping to form a refrigerant circuit, wherein the relay unit consists of a first piping and a first path for flowing refrigerant from the plurality of indoor units to the relay unit, a first switching device provided in the first path for individually blocking or allowing the flow of each refrigerant from the plurality of indoor units to the relay unit, and a second piping and a second path for flowing refrigerant from the relay unit to the plurality of indoor units. The system comprises two pathways, a second switchgear provided in the second pathway for individually shutting off or allowing the flow of refrigerant branching from the relay unit to multiple indoor units, a third pathway consisting of a third pipe for refrigerant to flow from multiple indoor units to the relay unit, a fourth pathway consisting of a fourth pipe for refrigerant to flow from the relay unit to multiple indoor units, a first shutoff device that opens when de-energized to allow refrigerant flow in the fourth pathway and closes when energized to shut off refrigerant flow in the fourth pathway, and a vacuum switchgear that opens when de-energized to allow fluid flow in at least one of the first, second, third, and fourth pathways and closes when energized to shut off refrigerant flow in at least one pathway. The first and second switching devices, or one or both, also serve as vacuum switching devices, opening when de-energized and closing when energized. The first switching device has a plurality of first switching sections corresponding to a plurality of indoor units, and the second switching device has a plurality of second switching sections corresponding to a plurality of indoor units. Each of the plurality of first switching sections and the plurality of second switching sections, or one or both, is an electronic expansion valve. It is.

[0011] The vacuuming method for an air conditioning system according to this disclosure is a method for vacuuming the refrigerant circuit of the above-mentioned air conditioning system, wherein the vacuuming is performed by driving a vacuum pump connected to a service port provided in the refrigerant circuit in an unpowered state in which the air conditioning system is not powered. [Effects of the Invention]

[0012] The air conditioning system according to this disclosure has a second and a fourth path, which are paths for refrigerant to flow from a relay unit to multiple indoor units. The second path is provided with a second switch, and the fourth path is provided with a first shut-off device. The air conditioning system also includes a vacuum switch that, when de-energized, is open to allow fluid flow in at least one of the first, second, third, and fourth paths, and when energized it is closed to shut off the flow of refrigerant in at least one path. In the event of a refrigerant leak, the air conditioning system can shut off the flow of refrigerant from the outdoor unit to the indoor units by closing the second switch, the first shut-off device, and the vacuum switch. Furthermore, when de-energized the air conditioning system opens the vacuum switch, it can allow fluid flow in at least one of the first, second, third, and fourth paths, thereby ensuring a vacuum path. For this reason, the air conditioning system can operate simultaneously for cooling and heating, has a shut-off function in case of refrigerant leaks, and is designed to improve ease of installation. [Brief explanation of the drawing]

[0013] [Figure 1] This is a schematic diagram showing an example of the configuration of an air conditioning system according to Embodiment 1. [Figure 2] This is a schematic diagram showing an example of the refrigerant flow in the full cooling operation mode of the air conditioning system according to Embodiment 1. [Figure 3] This is a schematic diagram showing an example of refrigerant flow in the cooling-dominant operation mode of an air conditioning system according to Embodiment 1. [Figure 4] This is a schematic diagram showing an example of refrigerant flow in the heating-dominant operation mode of the air conditioning system according to Embodiment 1. [Figure 5] This is a schematic diagram showing an example of the refrigerant flow in the full heating mode of the air conditioning system according to Embodiment 1. [Figure 6] This is a schematic diagram showing an example of refrigerant flow during refrigerant leakage in an air conditioning system according to Embodiment 1. [Figure 7] This is a schematic diagram showing an example of the airflow during vacuuming of an air conditioning system according to Embodiment 1. [Figure 8]It is a schematic diagram showing an example of a connection method of an external circuit 76 related to evacuation in the air conditioner according to Embodiment 1. [Figure 9] It is a schematic diagram showing an example of the flow of refrigerant when there is a refrigerant leak in the air conditioner according to Embodiment 2. [Figure 10] It is a schematic diagram showing an example of the flow of refrigerant when there is a refrigerant leak in the air conditioner according to Embodiment 3. [Figure 11] It is a schematic diagram showing an example of the flow of refrigerant when there is a refrigerant leak in the air conditioner according to Embodiment 4. [Figure 12] It is a schematic diagram showing an example of the flow of refrigerant when there is a refrigerant leak in the air conditioner according to Embodiment 5. [Figure 13] It is a schematic configuration diagram of a solenoid valve with an orifice in the air conditioner according to Embodiment 5. [Figure 14] It is an operation explanatory diagram of a solenoid valve with an orifice in the air conditioner according to Embodiment 5, showing the state where the solenoid valve with an orifice is open. [Figure 15] It is an operation explanatory diagram of a solenoid valve with an orifice in the air conditioner according to Embodiment 5, showing the state where the solenoid valve with an orifice is closed. [Figure 16] It is a schematic diagram showing an example of the flow of air for evacuation in the air conditioner according to Embodiment 5. [Embodiments for Carrying Out the Invention]

[0014] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In each figure, the same or corresponding parts are denoted by the same reference numerals, and the description thereof will be omitted or simplified as appropriate. Also, regarding the configurations shown in each figure, the shape, size, arrangement, etc. can be appropriately changed within the scope of the present disclosure.

[0015] [Embodiment 1] [Components] Figure 1 is a schematic diagram showing an example of the configuration of an air conditioning system 100 according to Embodiment 1. The air conditioning system 100 includes an outdoor unit 81, a repeater 82, and a plurality of indoor units 83a, 83b, and 83c. The air conditioning system 100 is a multi-type air conditioning system capable of simultaneous cooling and heating operation, where cooling and heating are performed simultaneously in each of the multiple indoor units 83a, 83b, and 83c. Here, an example is shown for the case where there are three indoor units 83, but there may be two or four or more.

[0016] The air conditioning system 100 includes a repeater 82 between the outdoor unit 81 and the multiple indoor units 83a, 83b, and 83c. The multiple indoor units 83a, 83b, and 83c are connected in parallel to the repeater 82.

[0017] The outdoor unit 81 and the relay unit 82 are connected by a high-pressure pipe 7 and a low-pressure pipe 8. High-pressure refrigerant flows from the outdoor unit 81 to the relay unit 82 through the high-pressure pipe 7. The high-pressure pipe 7 is equipped with a high-pressure side control valve 4 and a high-pressure pipe service port 71. Low-pressure refrigerant flows from the relay unit 82 to the outdoor unit 81 through the low-pressure pipe 8. The low-pressure pipe 8 is equipped with a low-pressure side control valve 5 and a low-pressure pipe service port 72. Here, the high and low pressures are not determined in relation to a reference pressure (numerical value), but are expressed based on relative high and low pressures.

[0018] The repeater 82 and the indoor unit 83a are connected by a liquid branch pipe 42a and a gas branch pipe 43a. The repeater 82 and the indoor unit 83b are connected by a liquid branch pipe 42b and a gas branch pipe 43b. The repeater 82 and the indoor unit 83c are connected by a liquid branch pipe 42c and a gas branch pipe 43c. The air conditioning system 100 has an outdoor unit 81, a repeater 82, and multiple indoor units 83a, 83b, and 83c, which are connected by refrigerant piping including a high-pressure pipe 7, a low-pressure pipe 8, liquid branch pipes 42a, 42b, and 42c, and gas branch pipes 43a, 43b, and 43c, forming a refrigerant circuit A through which the refrigerant circulates.

[0019] In the following, for example, in the case of indoor units 83a, 83b, and 83c, the subscripts a, b, and c will be omitted if there is no need to distinguish or specify them. Similarly, in the case of other equipment, the subscripts a, b, and c may be omitted if there is no need to distinguish or specify them.

[0020] [Outdoor unit 81] The outdoor unit 81 includes a compressor 1, a flow path switching device 2, an outdoor heat exchanger 3, a high-pressure side operating valve 4, a high-pressure pipe service port 71, a low-pressure side operating valve 5, a low-pressure pipe service port 72, and a check valve block 6.

[0021] (Compressor 1) Compressor 1 draws in a low-temperature, low-pressure refrigerant, compresses the drawn-in refrigerant to make it high-temperature and high-pressure, and discharges the high-temperature and high-pressure refrigerant.

[0022] (Flow path switching device 2) The flow path switching device 2 switches the direction of refrigerant flow in refrigerant circuit A. The flow path switching device 2 is composed of a four-way valve. The flow path switching device 2 is not limited to a four-way valve; any device that can switch the direction of refrigerant flow in refrigerant circuit A is acceptable, and a similar effect can be achieved by, for example, a combination of a solenoid valve and a check valve, and the configuration is not limited.

[0023] (Outdoor heat exchanger 3) The outdoor heat exchanger 3 is, for example, a cross-fin type fin-and-tube heat exchanger composed of heat transfer tubes and numerous fins, which exchanges heat between the outside air and the refrigerant and dissipates heat.

[0024] (High-pressure side operating valve 4) The high-pressure side control valve 4 is composed of, for example, a two-way valve that can be switched between open and closed. The high-pressure side control valve 4 is installed on the high-pressure pipe 7. The high-pressure side control valve 4 is opened manually during the installation of the air conditioning system 100, which will be described later, and remains open unless it is closed manually for repairs or other reasons.

[0025] (High-voltage pipe service port 71) The high-pressure pipe service port 71 is a port to which a vacuum pump is connected during vacuuming or a refrigerant cylinder is connected during refrigerant charging. The high-pressure pipe service port 71 is located in the flow path that branches off from the high-pressure pipe 7 downstream of the high-pressure side control valve 4. Regardless of the open / closed state of the high-pressure pipe service port 71, the refrigerant can flow between the high-pressure side control valve 4 and the high-pressure pipe 7.

[0026] (Low-pressure side operating valve 5) The low-pressure side control valve 5 is composed of, for example, a two-way valve that can be switched between open and closed. The low-pressure side control valve 5 is installed in the low-pressure pipe 8. The low-pressure side control valve 5 is opened manually during the installation of the air conditioning system 100, which will be described later, and remains open unless it is closed manually for repairs or other reasons.

[0027] (Low-pressure pipe service port 72) The low-pressure pipe service port 72 is a port to which a vacuum pump is connected during vacuuming or a refrigerant cylinder is connected during refrigerant charging. The low-pressure pipe service port 72 is located in a flow path that branches off from the low-pressure pipe 8 upstream of the low-pressure side control valve 5. Regardless of the open / closed state of the low-pressure pipe service port 72, the refrigerant can flow between the low-pressure side control valve 5 and the low-pressure pipe 8.

[0028] (Check valve block 6) The check valve block 6 consists of four check valves and is provided to control the direction of the refrigerant flow. The check valve block 6 consists of check valves 6a, 6b, 6c, and 6d. Check valve 6a allows flow from the low-pressure side operating valve 5 to the flow path switching device 2, but does not allow flow in the reverse direction. Check valve 6b allows flow from the flow path switching device 2 to the high-pressure side operating valve 4, but does not allow flow in the reverse direction. Check valve 6c allows flow from the low-pressure side operating valve 5 to the outdoor heat exchanger 3, but does not allow flow in the reverse direction. Check valve 6d allows flow from the outdoor heat exchanger 3 to the high-pressure side operating valve 4, but does not allow flow in the reverse direction.

[0029] The outdoor unit 81, equipped with this check valve block 6, ensures that regardless of the operating mode, the refrigerant flow direction is such that in the low-pressure pipe 8, the flow is from the relay unit 82 to the outdoor unit 81, and in the high-pressure pipe 7, the flow is from the outdoor unit 81 to the relay unit 82.

[0030] The outdoor unit 81 switches between two flow directions depending on the state of the flow path switching device 2. When the flow path switching device 2 is in the first state, the components of the outdoor unit 81 are connected by piping so that the refrigerant flows in the following order: low-pressure side operating valve 5, check valve 6a, flow path switching device 2, compressor 1, flow path switching device 2, outdoor heat exchanger 3, check valve 6d, and high-pressure side operating valve 4. When the flow path switching device 2 is in the second state, the components of the outdoor unit 81 are connected by piping so that the refrigerant flows in the following order: low-pressure side operating valve 5, check valve 6c, outdoor heat exchanger 3, flow path switching device 2, compressor 1, flow path switching device 2, check valve 6b, and high-pressure side operating valve 4.

[0031] [Repeater 82] The repeater 82 is located between the outdoor unit 81 and the indoor unit 83 and switches the flow of refrigerant supplied from the outdoor unit 81 to the indoor unit 83. The repeater 82 is installed, for example, indoors and controls the flow of refrigerant according to the operation required by the indoor unit 83. The repeater 82 comprises a first branching section 17, a second branching section 18, a first flow rate control device 19, a second flow rate control device 20, an inlet branching section 22, and an outlet junction section 23.

[0032] (First branching point 17) The first branching section 17 is a part that relays refrigerant between the outdoor unit 81 and the gas side of the multiple indoor units 83. The first branching section 17 includes a first path 13, a first switchgear 300, a battery 600, a second path 14, and a second switchgear 310.

[0033] The first path 13 is a path through which refrigerant flows from multiple indoor units 83 to the relay unit 82, and is composed of the first piping 10. The first piping 10 is a low-pressure piping through which low-pressure refrigerant flows. One end of the first piping 10 is connected to the low-pressure pipe 8, and the other end branches into three, the same number as the indoor units 83. The other end of the first piping 10 branches out to correspond to each of the multiple indoor units 83. Specifically, the first piping 10 has a main pipe 10a and branch pipes 10b, 10c, and 10d. The branch pipes 10b, 10c, and 10d are connected to gas branch pipes 43a, 43b, and 43c, respectively, which correspond to indoor units 83a, 83b, and 83c. The branch pipes 10b, 10c, and 10d are connected to the corresponding branch pipes 9b, 9c, and 9d of the second piping 9 (described later) at the indoor units 83a, 83b, and 83c to form a junction, and the junction is connected to the gas branch pipes 43a, 43b, and 43c.

[0034] The first switchgear 300 is provided in the first piping 10 that constitutes the first path 13, and individually shuts off or allows the flow of each refrigerant from each indoor unit 83 to the relay unit 82. The first switchgear 300 has first switchable sections 30a, 30b, and 30c provided in correspondence with the indoor units 83a, 83b, and 83c. The first switchable sections 30 open when de-energized and close when energized to shut off the flow of refrigerant.

[0035] In Figure 1, the first switchgear 300 is provided with one first switchgear 30 for each indoor unit 83, but the configuration is not limited to this. The first switchgear 300 may also be configured to provide a single first switchgear 30 common to indoor units 83 that always operate in the same mode.

[0036] The first opening / closing section 30 is an opening / closing valve, and is composed of a solenoid valve. Embodiment 1 is a configuration in which vacuum is drawn from the first path 13, as described below, and the first opening / closing section 30 provided in the first path 13 is composed of a solenoid valve that maintains an open state by spring force or the like when not energized. The first opening / closing section 30 is a pilot-type solenoid valve that drives a pilot valve with electromagnetic force to induce refrigerant pressure, and drives the main valve with the pressure difference of the refrigerant. In the illustrated example, the first opening / closing section 30 is composed of one solenoid valve, but is not limited to this. The first opening / closing section 30 may be composed of multiple solenoid valves connected in parallel in order to reduce pressure loss in the solenoid valve. Alternatively, the first opening / closing section 30 may be composed of multiple solenoid valves connected in series, as described in the embodiments described later, in order to reduce the amount of refrigerant leakage.

[0037] Incidentally, power is supplied to the air conditioning system 100 only after the installation of the electrical circuits and refrigerant piping is complete and preparations for trial operation are finished. Therefore, during the vacuuming process performed at the stage of refrigerant piping installation, all equipment constituting the refrigerant circuit A is de-energized. Vacuuming may be performed from any of the first path 13, the second path 14, the third path 15 (described later), and the fourth path 16, but Embodiment 1 is a configuration in which vacuuming is performed from the first path 13. For this reason, the first switchgear 300 also serves as a vacuuming switchgear S, which enables the securing of the vacuuming path when all equipment is de-energized. The vacuuming switchgear S is a device that opens when de-energized to allow the flow of air or other fluids in the first path 13, and closes when energized to block the flow of refrigerant. Because the first switchgear 300 also serves as the vacuuming switchgear S, the air conditioning system 100 is configured to secure the vacuuming path when all equipment is de-energized.

[0038] The battery 600 is a power source that drives the first switchgear 300 in the event of a power outage. The battery 600 is provided to drive the first switchgear 300 and shut off refrigerant leakage even when power is not supplied to the air conditioning system 100. As described above, the first switchgear 300 opens when there is no power, so it remains open during a power outage. In this case, the air conditioning system 100 cannot shut off refrigerant leakage from the indoor unit 83 during a power outage. By connecting the battery 600 to the first switchgear 300, the air conditioning system 100 can prevent refrigerant leakage from the indoor unit 83 during a power outage, thereby increasing safety. The battery 600 has batteries 60a, 60b, and 60c corresponding to the first switchgear 30a, 30b, and 30c.

[0039] The second route 14 is a route for supplying refrigerant from the relay unit 82 to multiple indoor units 83, and is composed of the second piping 9. The second piping 9 is a high-pressure piping through which high-pressure refrigerant flows. One end of the second piping 9 is connected to the high-pressure pipe 7, and the other end branches into three, the same number as the number of indoor units 83. The other end of the second piping 9 branches out to correspond to each of the multiple indoor units 83. Specifically, the second piping 9 has a main pipe 9a and branch pipes 9b, 9c, and 9d. The branch pipes 9b, 9c, and 9d are connected to gas branch pipes 43a, 43b, and 43c, respectively, which correspond to indoor units 83a, 83b, and 83c. The branch pipes 9b, 9c, and 9d are connected to the corresponding branch pipes 10b, 10c, and 10d of the first piping 10 at each of the indoor units 83a, 83b, and 83c to which they are connected, forming a junction, and the junction is connected to the gas branch pipes 43a, 43b, and 43c.

[0040] The second switchgear 310 is provided in the second piping 9 that constitutes the second path 14, and individually shuts off or allows the flow of each refrigerant that branches off from the relay unit 82 to the multiple indoor units 83, and shuts it off in the event of a refrigerant leak. The second switchgear 310 has second switchgear sections 31a, 31b, and 31c provided in correspondence with the indoor units 83a, 83b, and 83c.

[0041] The second switchgear 310 has one second switchgear 31 for each indoor unit 83. The second switchgear 310 is not limited to having one second switchgear 31 for each indoor unit 83. The second switchgear 310 may also have a common second switchgear 31 for indoor units 83 that always operate in the same mode.

[0042] The second switching section 31 is an on / off valve, and is composed of a solenoid valve. In the illustrated example, the second switching section 31 is composed of one solenoid valve, but it is not limited to this. The second switching section 31 may be composed of multiple solenoid valves connected in parallel in order to reduce pressure loss in the solenoid valve. Alternatively, the second switching section 31 may be composed of multiple solenoid valves connected in series, as will be described in the embodiments described later, in order to reduce the amount of refrigerant leakage.

[0043] (Second branching point 18) The second branching section 18 is a section that relays refrigerant between the outdoor unit 81 and the liquid side of the multiple indoor units 83. The second branching section 18 includes a third path 15, a third switchgear 320, a fourth path 16, a fourth switchgear 330, and a battery 61.

[0044] The third route 15 is a route for refrigerant to flow from multiple indoor units 83 to the relay unit 82, and is composed of the third piping 12. The third piping 12 is an intermediate pressure piping through which refrigerant at an intermediate pressure between high pressure and low pressure flows. One end of the third piping 12 is connected to the main pipe 11a of the fourth piping 11, which will be described later, and the other end branches into three, the same number as the number of indoor units 83. The other end of the third piping 12 branches out to correspond to each of the multiple indoor units 83. Specifically, the third piping 12 has a main pipe 12a and branch pipes 12b, 12c, and 12d. One end of the main pipe 12a is connected to the main pipe 11a of the fourth piping 11. The other end of the main pipe 12a is connected to one end of the branch pipes 12b, 12c, and 12d. The other ends of the branch pipes 12b, 12c, and 12d are connected to the corresponding branch pipes 11b, 11c, and 11d of the fourth piping 11 (described later) in the indoor units 83a, 83b, and 83c to form a junction, which is then connected to the liquid branch pipes 42a, 42b, and 42c.

[0045] The third switchgear 320 is provided in the third piping 12 that constitutes the third path 15, and individually shuts off or allows the flow of each refrigerant from each indoor unit 83 to the relay unit 82. The third switchgear 320 has third switch sections 32a, 32b, and 32c provided corresponding to the indoor units 83a, 83b, and 83c. In the illustrated example, the third switch section 32 is provided in each of the branch pipes 12b, 12c, and 12d that branch off from the third piping 12, but it is not limited to this. The third switchgear 320 may also have a single third switch section 32 common to indoor units 83 that always operate in the same mode.

[0046] The third opening / closing section 32 is composed of a valve that controls the flow of refrigerant from the indoor unit 83 to the relay unit 82. In Embodiment 1, the third opening / closing section 32 is composed of a check valve. The check valve allows the flow of refrigerant from the indoor unit 83 to the relay unit 82 to pass through, but blocks the flow in the reverse direction. In Embodiment 1, the third opening / closing section 32 is composed of a check valve, but is not limited to this. The third opening / closing section 32 can be any device that can block the flow of refrigerant from the third piping 12 to the liquid branch pipe 42 during operation, and may be composed of a solenoid valve or the like. In addition, the third opening / closing section 32 may be composed of multiple check valves to reduce pressure loss in the check valve. Furthermore, the third opening / closing section 32 may be composed of an electronic expansion valve, as will be explained in the embodiments described later.

[0047] The fourth path 16 is a path for supplying refrigerant from the relay unit 82 to multiple indoor units 83, and is composed of the fourth piping 11. The fourth piping 11 is an intermediate pressure piping through which refrigerant at an intermediate pressure between high pressure and low pressure flows. One end of the fourth piping 11 is connected to the inlet branch 22, and the other end branches into three, the same number as the number of indoor units 83. The other end of the fourth piping 11 branches out to correspond to each of the multiple indoor units 83. Specifically, the fourth piping 11 has a main pipe 11a and branch pipes 11b, 11c, and 11d. One end of the main pipe 11a is connected to the inlet branch 22. The other end of the main pipe 11a is connected to one end of the branch pipes 11b, 11c, and 11d. The other ends of the branch pipes 11b, 11c, and 11d are connected to the corresponding branch pipes 12b, 12c, and 12d of the third piping 12 in the indoor units 83a, 83b, and 83c to form a junction, which is then connected to the liquid branch pipes 42a, 42b, and 42c.

[0048] The fourth switchgear 330 is installed in the fourth piping 11 that constitutes the fourth path 16, and individually controls the flow of each refrigerant from the relay unit 82 to each indoor unit 83, and individually blocks the flow in the reverse direction. The fourth switchgear 330 has fourth switch sections 33a, 33b, and 33c, which are provided corresponding to the indoor units 83a, 83b, and 83c. In the illustrated example, the fourth switch section 33 is provided in each of the branch pipes 11b, 11c, and 11d that branch off from the fourth piping 11, but it is not limited to this. The fourth switchgear 330 may also have a single third switch section 32 common to indoor units 83 that always operate in the same mode.

[0049] The fourth opening / closing section 33 is composed of a valve that controls the flow of refrigerant from the relay unit 82 to the indoor unit 83. In Embodiment 1, the fourth opening / closing section 33 is composed of a check valve. The check valve allows the flow of refrigerant from the relay unit 82 to the indoor unit 83 to pass through, but blocks the flow in the reverse direction. In Embodiment 1, the fourth opening / closing section 33 is composed of a check valve, but is not limited to this. The fourth opening / closing section 33 can be any device that can block the flow of refrigerant from the liquid branch pipe 42 to the fourth piping 11 during operation, and may use a solenoid valve or the like. Also, the fourth opening / closing section 33 may be composed of multiple check valves to reduce pressure loss in the check valve. Furthermore, the fourth opening / closing section 33 may be composed of an electronic expansion valve, as will be explained in the embodiments described later.

[0050] The first shut-off device 21 opens when de-energized, allowing the flow of refrigerant through the fourth path 16, and closes when energized, blocking the flow of refrigerant through the fourth path 16. The first shut-off device 21 is an on-off valve that is maintained in an open state by spring force or the like when de-energized, and is composed of a solenoid valve. The first shut-off device 21 is installed on the main pipe 11a of the fourth piping 11. From the viewpoint of component cost, it is desirable to install the first shut-off device 21 on the main pipe 11a of the fourth piping 11 as shown in the figure. However, from the viewpoint of pressure loss, it is also possible to install the first shut-off device 21 on each of the branch pipes 11b, 11c, and 11d of the fourth piping 11, and not install the fourth on-off sections 33a, 33b, and 33c.

[0051] The first shut-off device 21 is connected to a battery 61, which is the power source that drives it during a power outage. The battery 61 is provided to drive the first shut-off device 21 and shut off refrigerant leakage even when power is not supplied to the air conditioner 100. Because the battery 61 is connected to the first shut-off device 21, the air conditioner 100 can prevent refrigerant leakage during a power outage, thereby enhancing safety.

[0052] In the illustrated example, the first shut-off device 21 is composed of a single solenoid valve installed in the main pipe 11a of the fourth piping 11. However, as described above, it may be composed of multiple solenoid valves installed in the branch pipes 11b, 11c, and 11d of the fourth piping 11. In other words, the first shut-off device 21 may be composed of multiple solenoid valves connected in series to the fourth opening / closing sections 33a, 33b, and 33c in the branch pipes 11b, 11c, and 11d. An air conditioning system with this configuration can obtain the same effects as described above. An air conditioning system with this configuration also has the effect of being able to shut off only the indoor unit 83 with refrigerant leakage, allowing the indoor unit 83 without refrigerant leakage to continue heating and cooling operation.

[0053] (First flow control device 19) The first flow control device 19 is installed in the piping that branches off from between the second flow control device 20 and the first shut-off device 21 in the main pipe 11a of the fourth piping 11 and forms a flow path toward the outlet junction 23. The first flow control device 19 is composed of, for example, a solenoid valve or expansion valve driven by a stepping motor.

[0054] (Second flow control device 20) The second flow control device 20 is installed in the main pipe 11a of the fourth piping 11, between the inlet branch 22 and the first shut-off device 21. The second flow control device 20 is composed of, for example, a solenoid valve or expansion valve driven by a stepping motor.

[0055] (Entrance branch section 22) The inlet branching section 22 is the part that branches the refrigerant flowing from the high-pressure pipe 7 to the relay unit 82 to the first branching section 17 and to the second branching section 18.

[0056] (Exit merging section 23) The outlet confluence section 23 is the part where the refrigerants from the first branch section 17 and the second branch section 18 that are headed towards the outdoor unit 81 are merged.

[0057] [Indoor unit 83] Indoor unit 83a has a pressure reducing device 40a and an indoor heat exchanger 41a. Indoor unit 83b has a pressure reducing device 40b and an indoor heat exchanger 41b. Indoor unit 83c has a pressure reducing device 40c and an indoor heat exchanger 41c.

[0058] (Depressurizing device 40) The pressure reducing device 40 can control the flow rate of the refrigerant and has a variable opening. Pressure reducing devices 40a, 40b, and 40c are composed of electronic expansion valves. The pressure reducing device 40 is connected to the relay unit 82 by a liquid branch pipe 42.

[0059] (Indoor heat exchanger 41) The indoor heat exchanger 41 is a cross-fin type fin-and-tube heat exchanger composed of, for example, heat transfer tubes and numerous fins, and performs heat exchange between the indoor air to be air-conditioned and the refrigerant. The indoor heat exchanger 41 is connected to the relay unit 82 by a gas branch pipe 43.

[0060] (Control devices 50, 51 and 52) The air conditioning system 100 includes a control device 50 installed on the outdoor unit 81 and a control device 51 installed on the repeater 82. Furthermore, the air conditioning system 100 includes a control device 52a installed on the indoor unit 83a, a control device 52b installed on the indoor unit 83b, and a control device 52c installed on the indoor unit 83c. While Figure 1 shows the control devices 52a, 52b, and 52c individually, the system is not limited to this configuration. For example, the air conditioning system 100 may integrate these components in any combination and install them on the outdoor unit 81 or the repeater 82, or on any of the multiple indoor units 83.

[0061] The processing circuits of the control devices 50, 51, and 52 consist of a CPU (also known as a Central Processing Unit, central processing unit, processing unit, arithmetic unit, microprocessor, microcomputer, or processor) that executes a program stored in dedicated hardware or memory.

[0062] When the processing circuits of control devices 50, 51, and 52 are dedicated hardware, the processing circuits may be, for example, single circuits, composite circuits, ASICs (Application Specific Integrated Circuits), FPGAs (Field Programmable Gate Arrays), or combinations thereof. Control devices 50, 51, and 52 may implement each of the functional units realized by the processing circuits with separate hardware, or each functional unit may be implemented with a single piece of hardware.

[0063] When the processing circuits of control devices 50, 51, and 52 are CPUs, each function performed by the processing circuit is realized by software, firmware, or a combination of software and firmware. The software and firmware are written as programs and stored in the memory. The CPU realizes each function of the processing circuit by reading and executing the programs stored in the memory. Note that some of the functions of the processing circuit may be realized by dedicated hardware, and some by software or firmware.

[0064] [Operating Mode] The air conditioning system 100 can circulate a refrigerant and perform air conditioning using a refrigeration cycle. The indoor unit 83 can select at least two operating modes, cooling or heating, according to user operation. The outdoor unit 81 can select one of the following multiple operating modes by switching the flow path switching device 2 according to the ratio of the total cooling load and the total heating load of the indoor unit 83.

[0065] The operating mode can be selected from three options: a full cooling mode in which all indoor units perform cooling, a full heating mode in which all indoor units perform heating, and a mixed mode in which cooling and heating are performed simultaneously. The mixed mode is further divided into a cooling-dominant mode in which the cooling load is large, and a heating-dominant mode in which the heating load is large. Here, the load ratio for switching between the cooling-dominant mode and the heating-dominant mode is approximately cooling:heating=1:1 as a guideline, but it can be designed arbitrarily.

[0066] The air conditioning system 100 operates a first opening / closing unit 30 located in the first path 13 and a second opening / closing unit 31 located in the second path 14 within the relay unit 82, according to the operating modes of the outdoor unit 81 and the indoor unit 83. By individually operating the first opening / closing unit 30 and the second opening / closing unit 31 according to each indoor unit 83, the air conditioning system 100 changes the direction of refrigerant flow in each indoor unit 83, thereby achieving simultaneous cooling and heating operation.

[0067] [Full Cooling Mode] Figure 2 is a schematic diagram showing an example of the refrigerant flow in the full cooling operation mode of the air conditioning system 100 according to Embodiment 1. The arrows indicate the flow of the refrigerant. The thick lines indicate the piping sections through which the refrigerant flows. Valves through which the refrigerant does not flow are indicated by dot hatching. The "Cool" label attached to the indoor unit 83 indicates that the indoor unit 83 is performing cooling, and the "Heat" label indicates that the indoor unit 83 is performing heating. These markings are the same for the operating modes described later.

[0068] In full cooling operation mode, control device 50 switches the flow path switching device 2 to the first state. Control device 51 closes the first flow control device 19 and the second on / off unit 31. Control device 51 opens the second flow control device 20, the first shut-off device 21 and the first on / off unit 30. Control device 52 controls the opening degree of the pressure reducing device 40. The high-pressure side operating valve 4 and the low-pressure side operating valve 5 are open.

[0069] Compressor 1 compresses the inhaled refrigerant and discharges high-temperature, high-pressure gaseous refrigerant. The gaseous refrigerant discharged from compressor 1 flows into the outdoor heat exchanger 3 via the flow path switching device 2. The refrigerant that flows into the outdoor heat exchanger 3 exchanges heat with a heat transfer medium that is colder than the refrigerant and condenses into a liquid. The heat transfer medium is either outdoor air or water. The condensed liquid refrigerant passes through the check valve 6d, the high-pressure side operating valve 4, the high-pressure pipe 7, and the inlet branch section 22.

[0070] The liquid refrigerant that has passed through the inlet branch section 22 passes through the second flow control device 20, the first shut-off device 21, and the fourth opening / closing section 33, and flows into the pressure reducing device 40 of the indoor unit 83 via the liquid branch pipe 42. The refrigerant that has flowed into the pressure reducing device 40 is depressurized and becomes a low-temperature two-phase refrigerant, which then flows into the indoor heat exchanger 41. The refrigerant that has flowed into the indoor heat exchanger 41 exchanges heat with a non-heat exchange medium that is hotter than the refrigerant, absorbs heat, and evaporates into a gas. The non-heat exchange medium is, for example, indoor air or water. At this time, the cooling effect is obtained as the non-heat exchange medium is cooled.

[0071] The refrigerant that flows out from the indoor heat exchanger 41 returns to the compressor 1 through the gas branch pipe 43, the first switching section 30, the low-pressure pipe 8, the low-pressure side operating valve 5, the check valve 6a, and the flow path switching device 2.

[0072] [Cooling-focused operation mode] Figure 3 is a schematic diagram showing an example of the refrigerant flow in the cooling-dominant operation mode of the air conditioning system 100 according to Embodiment 1.

[0073] The cooling-focused operation mode differs from the full-cooling operation mode in that some of the indoor units 83 perform heating operations. Here, we will explain using the case where indoor unit 83c performs heating operations as an example.

[0074] In cooling-dominant operation mode, it becomes necessary to flow a refrigerant at a higher temperature than the non-heat exchange medium to the indoor unit 83c that performs heating operation. Therefore, the control device 51 closes the second flow control device 20, closes the first opening / closing section 30c, and opens the second opening / closing section 31c.

[0075] The flow of refrigerant from compressor 1 to inlet branch 22 is the same as in full cooling operation, but the state of the refrigerant flowing out of outdoor unit 81 is different. In cooling-focused operation, the refrigerant flowing out of outdoor unit 81 is in a gas-liquid two-phase state. This is because the air conditioning system 100 does not release all of the heat contained in the refrigerant at the outdoor heat exchanger 3, but allows some of the refrigerant to reach the indoor heat exchanger 41 as a gas.

[0076] The refrigerant that flows out from compressor 1 and reaches inlet branch section 22 flows into indoor heat exchanger 41c via branch pipe 9d of second piping 9, second opening / closing section 31c, and gas branch pipe 43c.

[0077] The refrigerant flowing into the indoor heat exchanger 41c exchanges heat with a non-heat exchange medium that is at a lower temperature than the refrigerant, releasing heat and condensing into a liquid. At this time, the non-heat exchange medium is heated, resulting in a heating effect.

[0078] The refrigerant flowing out from the indoor heat exchanger 41c is depressurized in the pressure reducing device 40c, passes through the liquid branch pipe 42c and the first shut-off device 21, and then branches into two. The two branches of refrigerant flow into the pressure reducing devices 40a and 40b via the fourth switching section 33a and 33b and the liquid branch pipes 42a and 42b.

[0079] The refrigerant flowing into the pressure reducing devices 40a and 40b is depressurized to become a low-temperature two-phase refrigerant, which then flows into the indoor heat exchangers 41a and 41b. The refrigerant flowing into the indoor heat exchangers 41a and 41b exchanges heat with a non-heat exchange medium that is hotter than the refrigerant, absorbing heat and evaporating into a gas. At this time, the non-heat exchange medium is cooled, resulting in the cooling effect.

[0080] The refrigerant flowing out from the indoor heat exchangers 41a and 41b passes through the gas branch pipes 43a and 43b and the first switching sections 30a and 30b before merging. The merged refrigerant then returns to the compressor 1 through the low-pressure pipe 8, the low-pressure side operating valve 5, the check valve 6a, and the flow path switching device 2.

[0081] For simplicity, the control device 51 has been described as closing the first flow control device 19 and the second flow control device 20, but it may also be possible to open the first flow control device 19 and the second flow control device 20 to allow a portion of the refrigerant to flow.

[0082] When the first flow control device 19 is opened, the air conditioning system 100 returns a portion of the liquid refrigerant that has passed through the third opening / closing section 32c to the outdoor unit 81 instead of flowing it to the indoor units 83a and 83b that perform cooling. In this case, the air conditioning system 100 has the effect of adjusting the capacity ratio between cooling and heating, as well as adjusting the refrigerant distribution of the air conditioning system 100.

[0083] When the second flow control device 20 is opened, the air conditioning system 100 directs the refrigerant branched at the inlet branch 22 to the indoor units 83a and 83b that perform cooling, instead of to the indoor unit 83c that performs heating. Since liquid refrigerant does not condense, it can be said to be a refrigerant that contributes little to heating. By directing the liquid refrigerant, which contributes little to heating, to the indoor unit 83b that performs cooling, the air conditioning system 100 has the effect of reducing the pressure loss in the indoor unit 83c that performs heating. In addition, by reducing the amount of liquid refrigerant flowing to the indoor unit 83c that performs heating, the air conditioning system 100 may be able to improve the bias in the gas-liquid two-phase distribution in the header (not shown) of the indoor heat exchanger 41c.

[0084] Furthermore, since the refrigerant reduced in pressure by the pressure reducing device 40c becomes two-phase, noise is generated when the two-phase refrigerant flows into the pressure reducing devices 40a and 40b. To reduce this noise, the air conditioning system 100 may be equipped with a refrigerant-to-refrigerant heat exchanger that performs heat exchange between the high-pressure refrigerant flowing from the relay unit 82 to the pressure reducing device 40 and the refrigerant reduced by bypassing a portion of this high-pressure refrigerant to the first pipe 10.

[0085] [Heating-focused operation mode] Figure 4 is a schematic diagram showing an example of the refrigerant flow in the heating-dominant operation mode of the air conditioning system 100 according to Embodiment 1.

[0086] The heating-dominant operation mode differs from the cooling-dominant operation mode in that it involves an increased number of indoor units 83 performing heating operations. Here, we will explain using the case where indoor units 83b and 83c perform heating operations as an example.

[0087] As the number of indoor heating units 83 increases, the air conditioning system 100 experiences operating conditions where it cannot secure the necessary amount of heat for heating due to heat loss from the outdoor heat exchanger 3. Therefore, the control device 50 switches the flow path switching device 2 to the second state, ensuring heating capacity by allowing the outdoor heat exchanger 3 to function as an evaporator. Then, the control device 51 closes the first opening / closing sections 30b and 30c and opens the second opening / closing sections 31b and 31c.

[0088] Compressor 1 compresses the inhaled refrigerant and discharges high-temperature, high-pressure gaseous refrigerant. The gaseous refrigerant discharged from compressor 1 passes through the flow path switching device 2, check valve 6b, high-pressure side operating valve 4, high-pressure pipe 7, and inlet branch section 22.

[0089] The refrigerant that has passed through the inlet branch section 22 flows into the indoor heat exchangers 41b and 41c via the second opening / closing sections 31b and 31c and the gas branch pipes 43b and 43c. The refrigerant that has flowed into the indoor heat exchangers 41b and 41c exchanges heat with a non-heat exchange medium that is colder than the refrigerant, releasing heat and condensing into a liquid or two-phase state. At this time, the heating effect is obtained as the non-heat exchange medium is heated.

[0090] The refrigerant flowing out from the indoor heat exchangers 41b and 41c is depressurized in the pressure reducing devices 40b and 40c to become a two-phase refrigerant. The two-phase refrigerant passes through the liquid branch pipes 42b and 42c and the third switching section 32b and 32c and merges. The merged refrigerant passes through the first shut-off device 21, then flows through the fourth switching section 33a and the liquid branch pipe 42a into the pressure reducing device 40a.

[0091] The refrigerant flowing into the pressure reducing device 40a is depressurized and becomes a low-temperature two-phase refrigerant, which then flows into the indoor heat exchanger 41a. The refrigerant flowing into the indoor heat exchanger 41a exchanges heat with a non-heat exchange medium that is at a higher temperature than the refrigerant, absorbing heat and evaporating to become a two-phase refrigerant. At this time, the non-heat exchange medium is cooled, resulting in the cooling effect.

[0092] The refrigerant flowing out of the indoor heat exchanger 41a flows into the outdoor heat exchanger 3 through the gas branch pipe 43a, the first switching section 30a, the low-pressure pipe 8, the low-pressure side operating valve 5, and the check valve 6c. The refrigerant flowing into the outdoor heat exchanger 3 exchanges heat with a heat transfer medium that is hotter than the refrigerant, absorbs heat, and evaporates to become a gas or two-phase refrigerant. The gas or two-phase refrigerant returns to the compressor 1 through the flow path switching device 2.

[0093] For simplicity, the control device 51 has been described as closing the first flow control device 19 and the second flow control device 20, but it may also be possible to open the first flow control device 19 and the second flow control device 20 to allow a portion of the refrigerant to flow.

[0094] When the first flow control device 19 is opened, the air conditioning system 100 returns a portion of the liquid refrigerant that has passed through the third opening / closing sections 32b and 32c to the outdoor unit 81 instead of flowing it to the indoor unit 83a that performs cooling. In this case, the air conditioning system 100 has the effect of adjusting the capacity ratio between cooling and heating, as well as adjusting the refrigerant distribution of the air conditioning system 100.

[0095] When the second flow control device 20 is opened, the air conditioning system 100 directs the refrigerant branched at the inlet branch 22 to the indoor unit 83a that performs cooling, rather than to the indoor units 83b and 83c that perform heating. Since liquid refrigerant does not condense, it can be said to be a refrigerant that contributes little to heating. By directing the liquid refrigerant, which contributes little to heating, to the indoor unit 83a that performs cooling, the air conditioning system 100 has the effect of reducing the pressure loss in the indoor units 83b and 83c that perform heating.

[0096] Furthermore, since the refrigerant reduced in pressure by pressure reducers 40b and 40c becomes two-phase, noise is generated when the two-phase refrigerant flows into pressure reducers 40a and 40b. To reduce this noise, the air conditioning system 100 may be equipped with a refrigerant-to-refrigerant heat exchanger that performs heat exchange between the high-pressure refrigerant flowing from the relay unit 82 to the pressure reducer 40 and the refrigerant reduced by bypassing a portion of this high-pressure refrigerant to the first piping 10.

[0097] Furthermore, if the heat source temperature, which is the temperature of the heat transfer medium, is lower than the temperature of the heat exchange medium in the indoor unit 83, the refrigerant may not evaporate in the outdoor heat exchanger 3. In such cases, the air conditioning system 100 can lower the temperature of the refrigerant flowing into the outdoor heat exchanger 3 to below the heat source temperature by the following configuration: The air conditioning system 100 places a valve with an adjustable opening degree in the path from the indoor heat exchanger 41 to the outdoor heat exchanger 3, and by reducing the pressure of the refrigerant flowing from the indoor heat exchanger 41 to the outdoor heat exchanger 3, the temperature of the refrigerant flowing into the outdoor heat exchanger 3 is lowered to below the heat source temperature. For example, the air conditioning system 100 can adopt a configuration in which a solenoid valve is installed between the check valve 6c and the outdoor heat exchanger 3, or the check valve 6c is replaced with a solenoid valve, or a solenoid valve is installed between the indoor heat exchanger 41 and the gas branch pipe 43.

[0098] [Full heating mode] Figure 5 is a schematic diagram showing an example of the refrigerant flow in the full heating operation mode of the air conditioning system 100 according to Embodiment 1.

[0099] In full-heat operation mode, control device 50 switches the flow path switching device 2 to the second state. Control device 51 closes the second flow control device 20 and the first on / off unit 30. Control device 51 opens the first flow control device 19, the first shut-off device 21 and the second on / off unit 31. Control device 52 controls the opening degree of the pressure reducing device 40. The high-pressure side operating valve 4 and the low-pressure side operating valve 5 are open.

[0100] Compressor 1 compresses the inhaled refrigerant and discharges high-temperature, high-pressure gaseous refrigerant. The gaseous refrigerant discharged from compressor 1 passes through the flow path switching device 2, check valve 6b, high-pressure side operating valve 4, high-pressure pipe 7, and inlet branch section 22.

[0101] The refrigerant that has passed through the inlet branch section 22 flows into the indoor heat exchanger 41 via the second opening / closing section 31 and the gas branch pipe 43. The refrigerant that has flowed into the indoor heat exchanger 41 exchanges heat with a non-heat exchange medium that is at a lower temperature than the refrigerant, releasing heat and condensing into a liquid. At this time, the non-heat exchange medium is heated, which provides a heating effect.

[0102] The liquid refrigerant flowing out of the indoor heat exchanger 41 is depressurized by the pressure reducing device 40 and passes through the liquid branch pipe 42 and the third opening / closing section 32. The refrigerant that has passed through the third opening / closing section 32 flows into the outdoor heat exchanger 3 through the first flow control device 19, the low-pressure side operating valve 5, and the check valve 6c.

[0103] The refrigerant flowing into the outdoor heat exchanger 3 exchanges heat with a non-heat exchange medium that is hotter than the refrigerant, absorbing heat and evaporating to become a gas or two-phase refrigerant. The gas or two-phase refrigerant returns to the compressor 1 through the flow path switching device 2.

[0104] For simplicity, the case where the first shut-off device 21 is open has been explained here, but the operation is not affected even if the first shut-off device 21 is closed. This is because the flow of refrigerant is blocked by the fourth opening / closing part 33.

[0105] [Shut-off in case of refrigerant leak] Figure 6 is a schematic diagram showing an example of refrigerant flow during refrigerant leakage in the air conditioning system 100 according to Embodiment 1. The arrows indicate the flow of refrigerant. The thick lines indicate the piping area where the refrigerant is leaking.

[0106] Refrigerant leaks can occur due to damage to piping caused by pitting corrosion, faulty brazing, or breakage of piping due to disasters, etc.

[0107] If refrigerant leaks, the air conditioning system 100 detects the increase in refrigerant concentration using a refrigerant detector (not shown) installed in the indoor unit 83 and activates ventilation devices and other equipment installed in the indoor space.

[0108] If refrigerant leaks from the indoor unit 83, the air conditioning system 100 stops the operation of the compressor 1 and closes the first switchgear 300, the second switchgear 310, and the first shutoff device 21. This allows the air conditioning system 100 to shut off the flow of refrigerant from the outdoor unit 81 to the indoor unit 83 via the relay unit 82.

[0109] Multiple indoor units 83 are interconnected within the relay unit 82. Therefore, if an indoor unit experiencing refrigerant leakage (hereinafter referred to as a refrigerant-leaking indoor unit) remains connected to other indoor units (hereinafter referred to as non-refrigerant-leaking indoor units), the refrigerant from the non-refrigerant-leaking indoor unit may leak out of the refrigerant-leaking section 24 via the relay unit 82. Here, the refrigerant of a non-refrigerant-leaking indoor unit includes not only the refrigerant inside the non-refrigerant-leaking indoor unit, but also the refrigerant in the liquid branch pipe 42 and gas branch pipe 43 that are directly connected to the non-refrigerant-leaking indoor unit.

[0110] Therefore, if refrigerant leaks, the air conditioning system 100 stops the operation of the compressor 1 as described above, and closes the first switchgear 300, the second switchgear 310, and the first shutoff device 21, which also serve as the vacuum switchgear S. As a result, the air conditioning system 100 disconnects the indoor unit 83 with refrigerant leakage from the indoor unit 83 without refrigerant leakage in a flow path, as will be explained below, and prevents the refrigerant from the indoor unit 83 without refrigerant leakage from the refrigerant leakage section 24 via the relay unit 82.

[0111] The following describes the flow of refrigerant during a refrigerant leak. Here, we will explain using the case where the refrigerant leak point 24 is located in the liquid branch pipe 42a inside the indoor unit 83a as an example. The flow of refrigerant during a refrigerant leak described below is also the same when the refrigerant leak point 24 is located outside the indoor unit 83a in the liquid branch pipes 42a, liquid branch pipes 42b and 42c, indoor heat exchangers 41a, 41b and 41c, and gas branch pipes 43a, 43b and 43c.

[0112] Because the indoor unit 83a has a refrigerant leak section 24, the refrigerant from the first opening / closing section 30a and the second opening / closing section 31a, through the gas branch pipe 43a, the indoor heat exchanger 41a and the pressure reducing device 40a, to the refrigerant leak section 24 leaks to the outside through the refrigerant leak section 24.

[0113] Here, as described above, the air conditioning system 100 closes the first switchgear 300 and the second switchgear 310 when refrigerant leakage occurs. In other words, the first switchgear sections 30a, 30b, and 30c and the second switchgear sections 31a, 31b, and 31c are closed, and the first path 13 and the second path 14 are blocked. As a result, it is possible to prevent other refrigerants in the relay unit 82 from flowing into the gas branch pipe 43a, and other refrigerants in the relay unit 82 from leaking to the outside from the refrigerant leakage section 24 via the gas branch pipe 43a, the indoor heat exchanger 41a, and the pressure reducing device 40a.

[0114] Furthermore, the refrigerant in the liquid branch pipe 42a leaks to the outside through the refrigerant leak section 24. As the refrigerant in the liquid branch pipe 42a leaks to the outside, the pressure in the liquid branch pipe 42a decreases over time. As the pressure in the liquid branch pipe 42a becomes lower than the pressure in the fourth pipe 11, and the first shut-off device 21 is closed, a flow of refrigerant is generated in the fourth pipe 11, passing from the downstream side of the first shut-off device 21 through the fourth opening / closing section 33a towards the liquid branch pipe 42a. The refrigerant that has gone to the liquid branch pipe 42a leaks to the outside through the refrigerant leak section 24.

[0115] In the fourth pipe 11, the flow of refrigerant from the downstream side of the first shut-off device 21 through the fourth opening / closing section 33a toward the liquid branch pipe 42a causes the pressure in the fourth pipe 11 to decrease, resulting in a lower pressure in the fourth pipe 11 compared to the other pipes in the relay unit 82. Therefore, if the first shut-off device 21 were open, refrigerant from the other pipes in the relay unit 82 would flow into the liquid branch pipe 42a via the first shut-off device 21 and leak to the outside through the refrigerant leak section 24. However, by keeping the first shut-off device 21 closed, refrigerant leakage via the first shut-off device 21 can be prevented, thus preventing refrigerant from leaking from the other pipes in the relay unit 82.

[0116] Furthermore, the pressure in the fourth pipe 11 is lower than the pressure in the liquid branch pipes 42b and 42c. However, the fourth opening and closing sections 33b and 33c block the flow of refrigerant from the liquid branch pipes 42b and 42c toward the main pipe 11a of the fourth pipe 11. This prevents refrigerant in the non-refrigerant leaking indoor units 83b and 83c from flowing into the branch pipe 11b of the fourth pipe 11 via the liquid branch pipes 42b and 42c, thus preventing it from leaking to the outside from the refrigerant leak section 24.

[0117] As described above, the air conditioning system 100 stops the operation of the compressor 1 when a refrigerant leak occurs and closes the first switchgear 300, the second switchgear 310, and the first shutoff device 21. This allows the air conditioning system 100 to disconnect the indoor unit 83a with the refrigerant leak and the gas branch pipe 43 and liquid branch pipe 42 connected to the indoor unit 83a with the refrigerant leak from the rest of the refrigerant circuit A. As a result, the air conditioning system 100 can block the flow of refrigerant from the outdoor unit 81 to the indoor unit 83a with the refrigerant leak via the relay unit 82. In addition, the air conditioning system 100 can prevent refrigerant from the non-refrigerant leaking indoor units 83b and 83c from leaking out of the refrigerant leak section 24 via the relay unit 82. In other words, the air conditioning system 100 can limit the area of ​​piping from which refrigerant leaks in the indoor unit 83 to the inside of the leaking indoor unit 83a, the gas branch pipe 43a connected to the leaking indoor unit 83a, and the liquid branch pipe 42a. Therefore, the air conditioning system 100 can minimize the amount of refrigerant leaked in the event of a refrigerant leak.

[0118] As another configuration for blocking refrigerant leakage, for example, a configuration in which the pressure reducing device 40 has a shut-off function and the first shut-off device 21 is omitted is also conceivable. However, in that case, the refrigerant in the liquid branch pipes 42b and 42c leaks through the third opening / closing parts 32b and 32c, the main pipe 12a of the third piping 12, the main pipe 11a of the fourth piping 11, and the fourth opening / closing part 33a provided on the branch pipe 11b of the fourth piping 11. Therefore, this configuration results in a wider range of piping from which internal refrigerant leaks compared to the configuration of this embodiment 1. Such refrigerant leakage from liquid branch pipes can result in a large amount of leakage, which may be unacceptable in large-scale air conditioning systems with a large number of indoor units connected. The air conditioning system 100, by being equipped with the first shut-off device 21, can avoid such problems and is suitable for large-scale air conditioning systems with a large number of indoor units connected.

[0119] Here, we have described the case where the pressure reducing device 40a is open, but it is preferable for the pressure reducing device 40a to be closed. Due to its structure, the electronic expansion valve that constitutes the pressure reducing device 40a cannot completely close the flow path. Therefore, even when the pressure reducing device 40a is closed, the refrigerant in the indoor heat exchanger 41a and gas branch pipe 43a will leak out from the refrigerant leak section 24 via the pressure reducing device 40a. However, since the air conditioning system 100 can suppress the rate of refrigerant leakage from the refrigerant leak section 24 by closing the pressure reducing device 40a, it is preferable for the pressure reducing device 40a to be closed.

[0120] Furthermore, as described above, the first switchgear 300 and the first shut-off device 21 have the function of blocking refrigerant leakage. The first switchgear 300 is connected to a battery 600, and the first shut-off device 21 is connected to a battery 61, and they are configured to operate even in the event of a power outage. As a result, the air conditioning system 100 can be made even safer.

[0121] Incidentally, as described above, the air conditioning system 100 of Embodiment 1 is capable of simultaneous cooling and heating operation and has a configuration that shuts off the flow of refrigerant in the event of refrigerant leakage. As shown above, the air conditioning system 100 requires multiple opening and closing parts to enable simultaneous cooling and heating operation, which makes it easy for areas to become difficult to vacuum. However, with the above configuration, the air conditioning system 100 can reliably vacuum the entire refrigerant circuit A. Below, an example of vacuuming a part of the refrigerant circuit A will be described.

[0122] Vacuuming in the air conditioning system 100 is performed to remove air and moisture from the piping. If the air in the piping is not removed, the air will not undergo a phase change, leading to a decrease in the performance of the air conditioning system 100. If the air conditioning system 100 is operated without removing the air from the piping, the compressor 1 may be damaged if the refrigerant is highly flammable. In addition, if the moisture in the piping is not removed, the refrigerant oil may deteriorate, potentially causing the compressor 1 to malfunction. For these reasons, vacuuming is performed on the air conditioning system 100 during installation.

[0123] Here, we will summarize the configuration necessary to perform both simultaneous cooling and heating operation and refrigerant shutoff. In order for the air conditioning system 100 to enable simultaneous cooling and heating operation, it is necessary to have a first path 13, a second path 14, a third path 15, and a fourth path 16, as well as a first switchgear 300 and a second switchgear 310. Furthermore, in order for the air conditioning system 100 to shut off the refrigerant, it is necessary to have a first shutoff device 21 in the fourth path 16.

[0124] The air conditioning system 100 with the above configuration has a first switchgear 300 as a vacuum switching device S, which makes it possible to secure a vacuum path as described below.

[0125] In the air conditioning system 100 with the above configuration, vacuuming is performed from the first path 13. In other words, vacuuming is performed by allowing air to flow through the first path 13 without blocking it, drawing the air inside the relay unit 82 and indoor unit 83, etc., into the first path 13, and then using a vacuum pump to suck up the air drawn into the first path 13 and release it into the atmosphere.

[0126] [Vacuuming path] Figure 7 is a schematic diagram showing an example of the airflow during vacuuming of the air conditioning system 100 according to Embodiment 1. The arrows indicate the airflow during vacuuming.

[0127] Here, we show an example where the vacuum pump 25 is connected to the low-pressure pipe service port 72, but the vacuum pump can be connected to any location that allows the entire air conditioning system 100 to be evacuated, such as the high-pressure pipe service port 71.

[0128] However, since the repeater 82 and indoor unit 83 are installed in hard-to-reach locations such as the ceiling, it is desirable to connect the vacuum pump to the low-pressure pipe service port 72 or the high-pressure pipe service port 71 for ease of installation.

[0129] Since air is a gas, it is relatively easy to remove it by vacuuming. However, to completely remove moisture, it is necessary to achieve a vacuum level at which the moisture evaporates. For example, according to the November 1998 issue of "Refrigeration," published by the Japan Society of Refrigerating and Air Conditioning Engineers, vacuuming requires reducing the pressure inside the piping to an absolute pressure of 2 mmHg (approximately 270 Pa). This pressure is less than 1 / 300th of atmospheric pressure.

[0130] During the vacuuming process, the air conditioning unit 100 becomes low-pressure, causing devices driven by the refrigerant pressure difference, specifically pilot-operated solenoid valves, to malfunction. Therefore, if the air conditioning unit 100 is configured to secure the vacuum path by opening a pilot-operated solenoid valve, the vacuum path cannot be secured. For this reason, in order to secure the vacuum path, the air conditioning unit 100 needs to pre-open an expansion valve driven by a stepping motor and a solenoid valve whose open state is maintained by spring force.

[0131] The first flow control device 19, the second flow control device 20, and the pressure reducing device 40 are composed of valves driven by stepping motors and are open at a set opening degree at the time of factory shipment. In addition, the first opening / closing section 30 and the first shut-off device 21 are on-off valves that maintain an open state by spring force or the like when not energized, so when vacuuming is performed when not energized, the first opening / closing section 30 and the first shut-off device 21 are open. The open / closed state of the second opening / closing section 31 when performing vacuuming is not particularly limited, but here we will assume that the second opening / closing section 31 is closed.

[0132] The third opening / closing section 32 allows the flow of refrigerant from the indoor unit 83 to the relay unit 82 to pass through, while blocking the flow in the reverse direction. The third opening / closing section 32 allows the flow of refrigerant from the indoor unit 83 to the relay unit 82 to pass through, but after the vacuum pump 25 is driven, the air conditioning system 100 becomes low pressure, which also blocks the flow of vacuumed air from the indoor unit 83 to the relay unit 82. The check valve that constitutes the third opening / closing section 32 is generally structured to open by lifting the valve body due to the pressure difference between the inlet and outlet sides. Therefore, when the vacuum pump 25 is driven, the check valve cannot maintain the pressure difference between the inlet and outlet sides due to the low pressure inside the air conditioning system 100, and the valve body does not lift, resulting in a closed state and blocking the flow of vacuumed air. Thus, the flow of vacuumed air in the third path 15 is blocked by the third opening / closing section 32.

[0133] The fourth opening / closing section 33 allows the flow of refrigerant from the relay unit 82 to the indoor unit 83 to pass through, while blocking the flow in the reverse direction. The fourth opening / closing section 33 allows the flow of refrigerant from the relay unit 82 to the indoor unit 83 to pass through, but after the vacuum pump 25 is driven, the air conditioning system 100 becomes low pressure, which also blocks the flow of vacuumed air from the relay unit 82 to the indoor unit 83. The check valve that constitutes the fourth opening / closing section 33 is generally structured to open by lifting the valve body due to the pressure difference between the inlet and outlet sides. Therefore, when the vacuum pump 25 is driven, the check valve cannot maintain the pressure difference between the inlet and outlet sides due to the low pressure inside the air conditioning system 100, and the valve body does not lift, remaining closed and blocking the flow of vacuumed air. Thus, the flow of vacuumed air in the fourth path 16 is blocked by the fourth opening / closing section 33.

[0134] Based on the above, even when the power supply is not connected during the installation of the air conditioning system 100, the air conditioning system 100 ensures that the first path 13 is not interrupted and that a vacuum path is maintained.

[0135] [Airflow during vacuuming] When the vacuum pump 25 is activated, the air and moisture present in each pipe are drawn into the vacuum pump 25 and released into the atmosphere as follows.

[0136] Air and moisture present in the high-pressure pipe 7, the main pipe 9a of the second piping 9, and parts of the branch pipes 9b, 9c, and 9d are drawn into the vacuum pump 25 through the inlet branch section 22, the second flow control device 20, the first flow control device 19, the outlet junction 23, and the low-pressure pipe 8, and released into the atmosphere. Parts of the branch pipes 9b, 9c, and 9d refer to the piping on the main pipe 9a side of the branch pipes 9b, 9c, and 9d, which are divided into two by the second opening / closing sections 31a, 31b, and 31c. At this time, air and moisture present in the inlet branch section 22, the second flow control device 20, the first flow control device 19, the outlet junction 23, and the low-pressure pipe 8 are also drawn into the vacuum pump 25 and released into the atmosphere.

[0137] The air and moisture present in a portion of the main pipe 11a and portions of the branch pipes 11b, 11c, and 11d of the fourth piping 11 are drawn into the vacuum pump 25 through the first flow control device 19, the outlet junction 23, and the low-pressure pipe 8, and released into the atmosphere, because the first shut-off device 21 is open. The portion of the main pipe 11a of the fourth piping 11 is the portion on the side of the first shut-off device 21 from the connection point P1 between the piping where the first flow control device 19 is installed and the main pipe 11a. The portions of the branch pipes 11b, 11c, and 11d are the portions on the main pipe 11a side of the branch pipes 11b, 11c, and 11d, which are divided into two by the fourth opening / closing sections 33a, 33b, and 33c.

[0138] The air and moisture present in the main pipe 12a and parts of the branch pipes 12b, 12c, and 12d of the third piping 12 merge with the air and moisture present in the main pipe 11a of the fourth piping 11. The merged air and moisture are drawn into the vacuum pump 25 through the connection part P1, the first flow control device 19, the outlet junction 23, and the low-pressure pipe 8, and released into the atmosphere.

[0139] The air and moisture present in the remaining parts of branch pipes 11b, 11c, and 11d, the remaining parts of branch pipes 12b, 12c, and 12d, liquid branch pipes 42a, 42b, and 42c, indoor heat exchangers 41a, 41b, and 41c, gas branch pipes 43a, 43b, and 43c, and the first piping 10 pass through the first path 13 because the first opening / closing parts 30a, 30b, and 30c are open. The air and moisture that have passed through the first path 13 are drawn into the vacuum pump 25 through the outlet junction 23 and the low-pressure pipe 8 and released into the atmosphere.

[0140] The air and moisture present in the remaining parts of branch pipes 9b, 9c, and 9d are drawn into the air and moisture flow in branch pipes 10b, 10c, and 10d, and are sucked through the outlet confluence 23 and low-pressure pipe 8 to the vacuum pump 25 and released into the atmosphere.

[0141] As a result, the air conditioning system 100 can vacuum dry everything inside the piping of the relay unit 82, the indoor unit 83, the high-pressure pipe 7, and the low-pressure pipe 8.

[0142] Figure 7 shows an example of vacuuming from one location, but it is more preferable to vacuum from both the high-pressure pipe 7 and the low-pressure pipe 8. This is because the distance the air travels increases with distance from the vacuum pump 25, and therefore the vacuuming process takes longer.

[0143] In the above example, the first switchgear 300 also serves as the vacuum switchgear S, and vacuuming is performed from the first path 13. However, the second switchgear 310 may also serve as the vacuum switchgear S, and vacuuming may be performed from the second path 14.

[0144] [Vacuuming procedure] The following describes the specific procedure for performing a vacuum.

[0145] Prior to performing the vacuuming, the worker connects the outdoor unit 81, the relay unit 82, and the indoor unit 83 to form refrigerant circuit A. At this time, the worker confirms that the high-pressure side operating valve 4 and the low-pressure side operating valve 5 of the outdoor unit 81 are closed, and then connects the outdoor unit 81, the relay unit 82, and the indoor unit 83 using the high-pressure pipe 7, the low-pressure pipe 8, the liquid branch pipe 42, and the gas branch pipe 43.

[0146] Next, the worker fills refrigerant circuit A with a gas for airtightness testing and performs the airtightness test. For example, nitrogen gas is used as the gas for airtightness testing.

[0147] Next, the worker connects the external circuit 76, which will be described below, to the refrigerant circuit A.

[0148] Figure 8 is a schematic diagram showing an example of a connection method for the external circuit 76 involved in vacuuming in the air conditioning system 100 according to Embodiment 1. The arrows indicate the flow of air. Referring to Figure 8, an example of a preferred vacuuming procedure will be described.

[0149] Vacuuming is performed by an operator connecting an external circuit 76 to the refrigerant circuit A. The external circuit 76 includes a gauge manifold 70, a vacuum pump 25, and charging hoses 75a, 75b, and 75c. The gauge manifold 70 has three ports: a low-pressure port 70a, a high-pressure port 70b, and a supply port 70c. The gauge manifold 70 includes a low-pressure meter 70a1 capable of displaying the pressure acting on the low-pressure port 70a, and a high-pressure meter 70b1 capable of displaying the pressure acting on the high-pressure port 70b.

[0150] A vacuum pump 25 is connected to the supply port 70c of the gauge manifold 70 via a charging hose 75c. The vacuum pump 25 is connected to the charging hose 75c downstream of an external valve 74 located on the charging hose 75c in the vacuum airflow.

[0151] The external circuit 76 has a refrigerant cylinder 73 that stores refrigerant. The refrigerant cylinder 73 is connected to the charging hose 75c. After the vacuuming is complete, the circuit is filled with refrigerant. If the refrigerant cylinder 73 is connected to the charging hose 75c after the vacuuming is complete, there is a possibility that air may enter the vacuumed circuit during the connection. For this reason, it is preferable to connect the refrigerant cylinder 73 to the charging hose 75c before the vacuuming is completed.

[0152] During vacuuming, the external circuit 76 with the above configuration is connected to the refrigerant circuit A. Specifically, the charging hose 75a connected to the low-pressure port 70a of the gauge manifold 70 is connected to the low-pressure pipe service port 72. Also, the charging hose 75b connected to the high-pressure port 70b of the gauge manifold 70 is connected to the high-pressure pipe service port 71. The low-pressure pipe service port 72 and the high-pressure pipe service port 71 are, for example, of the valve-operated type, and the valves open when the corresponding charging hoses 75a and 75b are connected. The low-pressure pipe service port 72 and the high-pressure pipe service port 71 are covered with, for example, metal screw-on caps at the time of factory shipment, so that they cannot be accidentally opened.

[0153] The connection procedure is not limited to the above. After the gauge manifold 70 is connected to the refrigerant circuit A by charging hoses 75a and 75b, the charging hose 75c may be connected to the gauge manifold 70, and the vacuum pump 25 and refrigerant cylinder 73 may be connected to the charging hose 75c.

[0154] As a result, the external circuit 76 involved in vacuuming is connected to the refrigerant circuit A. The operator then manually opens the external valve 74. This opens the charging hose 75, high-pressure pipe 7, low-pressure pipe 8, relay unit 82, and indoor unit 83 to the atmosphere. During vacuuming, the external valve 74 remains open, and the valve 73a on the refrigerant cylinder 73 remains closed.

[0155] Next, the operator activates the vacuum pump 25. The operator confirms that a vacuum has been reached by referring to the vacuum meter attached to the vacuum pump 25. After the refrigerant circuit A reaches a vacuum, the operation of the vacuum pump 25 is continued to evaporate the moisture in the refrigerant circuit A. Next, the operator closes the external valve 74. After the external valve 74 is closed, the operator stops the vacuum pump 25 and leaves it for a predetermined time or longer. The operator checks the low-pressure meter 70a1 and the high-pressure meter 70b1, and if the pressure rise is less than the set change, the operator determines that there is no residual moisture and terminates the vacuuming.

[0156] After the vacuuming is complete, the operator charges the refrigerant. During refrigerant charging, the operator opens the high-pressure side control valve 4 and the low-pressure side control valve 5. Then, the operator opens valve 73a of the refrigerant cylinder 73. This charges the refrigerant in the refrigerant cylinder 73 into refrigerant circuit A. Refrigerant charging is performed while monitoring the low-pressure side meter 70a1 and the high-pressure side meter 70b1. The amount of refrigerant to be charged into refrigerant circuit A is calculated according to the manufacturer's specifications based on the length of the piping constituting refrigerant circuit A and the volumes of the relay unit 82 and the indoor unit 83. During refrigerant charging, valve 73a of the refrigerant cylinder 73 is opened, and the calculated amount of refrigerant is charged into refrigerant circuit A.

[0157] After refrigerant charging is complete, the high-pressure pipe service port 71 and the low-pressure pipe service port 72 are closed, and all external circuits are disconnected.

[0158] [Effects of Embodiment 1] The air conditioning system 100 of this embodiment 1 is an air conditioning system capable of simultaneous cooling and heating operation, which connects an outdoor unit 81, a plurality of indoor units 83, and a relay unit 82 with refrigerant piping to form a refrigerant circuit A. The relay unit 82 is composed of a first piping 10 and includes a first path 13 through which refrigerant flows from the plurality of indoor units 83 to the relay unit 82, and a first switchgear 300 provided in the first path 13 to individually shut off or allow the flow of each refrigerant flowing from the plurality of indoor units 83 to the relay unit 82. The relay unit 82 is composed of a second piping 9 and includes a second path 14 through which refrigerant flows from the relay unit 82 to the plurality of indoor units 83, and a second switchgear 310 provided in the second path 14 to individually shut off or allow the flow of each refrigerant that branches off from the relay unit 82 and flows to the plurality of indoor units 83. The relay unit 82 comprises a third pipe 12 and a third path 15 through which refrigerant flows from multiple indoor units 83 to the relay unit 82, and a fourth pipe 11 and a fourth path 16 through which refrigerant flows from the relay unit 82 to multiple indoor units 83. The relay unit 82 includes a first shut-off device 21 that opens when de-energized to allow the flow of refrigerant in the fourth path 16, and closes when energized to block the flow of refrigerant in the fourth path 16. The relay unit 82 also includes a second branch 18 which comprises a vacuum switch S that opens when de-energized to allow the flow of fluid in at least one of the first path 13, second path 14, third path 15, and fourth path 16, and closes when energized to block the flow of refrigerant in at least one of the paths.

[0159] With the above configuration, the air conditioning system 100 can shut off the flow of refrigerant from the outdoor unit 81 to the indoor unit 83 by closing the second switchgear 310, the first shutoff device 21, and the vacuum switchgear S in the event of a refrigerant leak. Furthermore, when the air conditioning system 100 is not energized, the vacuum switchgear S opens, allowing fluid flow in at least one of the first path 13, the second path 14, the third path 15, and the fourth path 16, thereby ensuring a vacuum path. As a result, the air conditioning system 100 can operate both heating and cooling simultaneously, has a shutoff function in case of a refrigerant leak, and improves ease of installation. In other words, the air conditioning system 100 can achieve both safety in the event of a refrigerant leak and improved ease of installation.

[0160] The air conditioning system 100 is equipped with a battery 61 that drives the first shutoff device 21 in the event of a power outage.

[0161] With the above configuration, the air conditioning system 100 can prevent refrigerant leakage during a power outage, thereby enhancing safety.

[0162] The fourth piping 11 includes a main pipe 11a and a plurality of branch pipes 11b, 11c, and 11d that branch off from the main pipe 11a toward a plurality of indoor units 83. The first shut-off device 21 consists of a solenoid valve installed on the main pipe 11a of the fourth piping 11.

[0163] With the above configuration, the air conditioning system 100 can reduce costs compared to a configuration in which the first shut-off device 21 is provided with solenoid valves in each of the multiple branch pipes 11b, 11c, and 11d.

[0164] The fourth piping 11 includes a main pipe 11a and a plurality of branch pipes 11b, 11c, and 11d that branch off from the main pipe 11a toward a plurality of indoor units 83. The first shut-off device 21 consists of a plurality of solenoid valves provided in the plurality of branch pipes 11b, 11c, and 11d of the fourth piping 11.

[0165] With the above configuration, the air conditioning system 100 can shut off only the indoor unit 83 with refrigerant leakage, allowing the indoor unit 83 without refrigerant leakage to continue heating and cooling operations.

[0166] The air conditioning system 100 is equipped with a battery 60 that drives the vacuum switchgear S in the event of a power outage.

[0167] With the above configuration, the air conditioning system 100 can prevent refrigerant leakage during a power outage, thereby enhancing safety.

[0168] In the air conditioning system 100, one or both of the first switchgear 300 and the second switchgear 310 also serve as a vacuum switchgear S, which opens when de-energized and closes when energized.

[0169] With the above configuration, the air conditioning system 100 can perform vacuuming from either or both of the first path 13 and the second path 14.

[0170] [Embodiment 2] Figure 9 is a schematic diagram showing an example of refrigerant flow during refrigerant leakage in the air conditioning system 101 according to Embodiment 2. The arrows indicate the flow of refrigerant. The thick lines indicate the piping range in which the internal refrigerant leaks. Compared to the air conditioning system 100 of Embodiment 1, the air conditioning system 101 of Embodiment 2 differs in the configuration of one or both of the first opening / closing section 30 and the second opening / closing section 31, which also serve as the vacuum switching device S. The following description will focus on the configurations in Embodiment 2 that differ from those in Embodiment 1, and configurations not described in Embodiment 2 are the same as those in Embodiment 1.

[0171] In Embodiment 1, the first opening / closing unit 30 is a pilot-operated solenoid valve, which drives the pilot valve with electromagnetic force to induce refrigerant pressure, and drives the main valve with the pressure difference of the refrigerant. In contrast, in Embodiment 2, the first opening / closing unit 30 is an electronically adjustable expansion valve driven by a stepping motor or the like.

[0172] During normal operation of the air conditioning system 101, the pressure in the first piping 10 is always lower than that in the gas branch pipe 43, thus ensuring a refrigerant pressure difference. However, in the event of a refrigerant leak, the pressure in the gas branch pipe 43 may become lower than that in the first piping 10. Therefore, if the first opening / closing section 30 is a pilot-operated solenoid valve, the main valve may be pushed up by the pressure during a refrigerant leak, opening the flow path and potentially failing to adequately perform its shut-off function.

[0173] In contrast, the air conditioning system 101, with its first opening / closing section 30 being an electronic expansion valve, can reliably shut off the flow of refrigerant in the first path 13 regardless of whether the pressure in the first piping 10 is lower than that in the gas branch pipe 43 when refrigerant leaks.

[0174] The air conditioning unit 101 performs heating and cooling operations similar to those in Embodiment 1. The air conditioning unit 101 can also improve its operation in the heating-dominant operation mode by adjusting the opening degree of the first opening / closing section 30.

[0175] As mentioned above, when the heat source temperature of an air conditioning system is lower than the temperature of the heat exchange medium in the indoor unit, the temperature of the refrigerant flowing into the outdoor heat exchanger must be lower than the heat source temperature. To lower the refrigerant temperature below the heat source temperature, it is desirable to install a valve with adjustable opening in the path from the indoor heat exchanger to the outdoor heat exchanger.

[0176] In the second embodiment of the air conditioning system 101, the first opening / closing section 30 is an electronic expansion valve, and by reducing the pressure of the refrigerant in the first opening / closing section 30, the temperature of the refrigerant flowing into the outdoor heat exchanger 3 can be lowered. Therefore, the first opening / closing section 30 of the air conditioning system 101 can play a role in lowering the temperature of the refrigerant flowing into the outdoor heat exchanger 3 to below the heat source temperature.

[0177] Figure 9 shows an example where only the first opening / closing section 30 is composed of an electronic expansion valve driven by a stepping motor or the like, but the air conditioning system 101 is not limited to this configuration. The air conditioning system 101 may also have a second opening / closing section 31 composed of an electronic expansion valve driven by a stepping motor or the like. Furthermore, the air conditioning system 101 may have both the first opening / closing section 30 and the second opening / closing section 31 composed of electronic expansion valves. In short, the air conditioning system 101 includes a configuration in which one or both of the first opening / closing section 30 and the second opening / closing section 31 are electronic expansion valves. When the air conditioning system 101 has a second opening / closing section 31 composed of an electronic expansion valve, the effect on pressure adjustment in the heating-dominant operation mode cannot be obtained, but other effects can be obtained.

[0178] [Shut-off in case of refrigerant leak] In the event of a refrigerant leak, as shown in Figure 9, the air conditioning system 101 closes the first switchgear 300, the second switchgear 310, and the first shut-off device 21. Here, compared to the air conditioning system 100, the air conditioning system 101 has one or both of the first switchgear 30 constituting the first switchgear 300 and the second switchgear 31 constituting the second switchgear 310 configured as electronic expansion valves. As a result, the air conditioning system 101 can reliably shut off the flow of refrigerant in one or both of the first path 13 and the second path 14 in the event of a refrigerant leak, compared to the air conditioning system 100. Consequently, the air conditioning system 102 can reduce the amount of refrigerant leakage to a smaller amount compared to the air conditioning system 100.

[0179] [Vacuuming] One or both of the electronic expansion valves constituting the first opening / closing section 30 and the electronic expansion valves constituting the second opening / closing section 31 are open to a set opening degree at the time of factory shipment. In other words, one or both of the electronic expansion valves constituting the first opening / closing section 30 and the electronic expansion valves constituting the second opening / closing section 31 are open when the system is not energized. This allows the air conditioning system 101 to ensure a vacuum path.

[0180] [Effects of the air conditioning system 101 of Embodiment 2] The air conditioning system 101 provides the same effects as in Embodiment 1, and because one or both of the first opening / closing section 30 and the second opening / closing section 31 are configured as electronic expansion valves, the following advantages are obtained compared to the case where they are configured as solenoid valves: The air conditioning system 101 can reduce the amount of refrigerant leakage to a smaller amount compared to the air conditioning system 100.

[0181] [Embodiment 3] Figure 10 is a schematic diagram showing an example of refrigerant flow during refrigerant leakage in the air conditioning system 102 according to Embodiment 3. The arrows indicate the flow of refrigerant. The thick lines indicate the piping range in which the refrigerant is leaking. Compared to the air conditioning system 100 of Embodiment 1, the air conditioning system 102 of Embodiment 3 differs in the configuration of one or both of the first opening / closing section 30 and the second opening / closing section 31, which also serve as the vacuum switching device S. The following description will focus on the configurations in Embodiment 3 that differ from those in Embodiment 1, and configurations not described in Embodiment 3 are the same as those in Embodiment 1.

[0182] In Embodiment 3, the first opening / closing section 30 has a configuration in which two solenoid valves are provided in series, and which are maintained in an open state by spring force or the like when not energized. The configuration includes two pilot-operated solenoid valves provided in series. The solenoid valve on the gas branch pipe 43 side performs a shut-off function in the event of refrigerant leakage. The solenoid valve on the gas branch pipe 43 side performs a shut-off function when the pressure in the gas branch pipe 43 becomes lower than the pressure in the first piping 10. The solenoid valve on the first piping 10 side performs a shut-off function during normal operation. The solenoid valve on the first piping 10 side performs a shut-off function when the pressure in the first piping 10 becomes lower than the pressure in the gas branch pipe 43.

[0183] Therefore, similar to Embodiment 2, the air conditioning system 102 can reliably shut off the flow of refrigerant in the first path 13 regardless of whether the first pipe 10 is at a lower pressure than the gas branch pipe 43 when refrigerant leaks.

[0184] Figure 10 shows an example where only the first switching unit 30 has a configuration of two pilot-operated solenoid valves connected in series, but the air conditioning system 102 is not limited to this configuration. The air conditioning system 102 may also have a configuration where the second switching unit 31 has two pilot-operated solenoid valves connected in series. Furthermore, the air conditioning system 102 may have a configuration where both the first switching unit 30 and the second switching unit 31 have two pilot-operated solenoid valves connected in series. In short, the air conditioning system 102 includes a configuration in which one or both of the first switching unit 30 and the second switching unit 31 have two pilot-operated solenoid valves connected in series.

[0185] [Shut-off in case of refrigerant leak] In the event of a refrigerant leak, as shown in Figure 10, the air conditioning system 102 closes the first switchgear 300, the second switchgear 310, and the first shut-off device 21. Here, compared to the air conditioning system 100, the air conditioning system 102 has a configuration in which one or both of the first switchgear 30 constituting the first switchgear 300 and the second switchgear 31 constituting the second switchgear 310 are connected in series with two pilot-operated solenoid valves. As a result, the air conditioning system 102 can reliably shut off the flow of refrigerant in one or both of the first path 13 and the second path 14 in the event of a refrigerant leak, compared to the air conditioning system 100.

[0186] [Vacuuming] During vacuuming, that is, when the system is not energized, both of the two solenoid valves constituting the third opening / closing section 32 open, allowing the air conditioner 102 to secure a vacuum path from the third path 15. In this case, since the air conditioner 102 can secure a vacuum path from the third path 15, the battery 600 that was required when vacuuming was performed from the first path 13 becomes unnecessary.

[0187] If the fourth opening / closing section 33 is configured with two pilot-operated solenoid valves connected in series, a vacuum path can be secured from the fourth path 16. In this case, since the air conditioning unit 102 can secure a vacuum path from the fourth path 16, the battery 600 that was required when vacuuming was performed from the first path 13 becomes unnecessary.

[0188] If both the third opening / closing section 32 and the fourth opening / closing section 33 are configured with two pilot-operated solenoid valves connected in series, then vacuum paths can be secured from the third path 15 and the fourth path 16, eliminating the need for the battery 600 that was required when vacuuming was performed from the first path 13.

[0189] [Effects of the air conditioning system 102 of Embodiment 3] The air conditioning system 102 provides the same effects as in Embodiment 1, as well as the following effects. In the air conditioning system 102, one or both of the first opening / closing section 30 and the second opening / closing section 31 are configured with two pilot-operated solenoid valves connected in series. As a result, the air conditioning system 102 can reduce the amount of refrigerant leakage to a smaller amount compared to the case where one or both of the first opening / closing section 30 and the second opening / closing section 31, which also serve as the vacuum opening / closing device S, are configured with a single pilot-operated solenoid valve.

[0190] Here, the operation of the solenoid valve is faster than that of an electronically adjustable expansion valve using a stepping motor. Therefore, the air conditioner 102 can close the flow path more quickly than the air conditioner 101 in which one or both of the first opening / closing section 30 and the second opening / closing section 31 are configured with electronically adjustable expansion valves, and thus can reduce the amount of refrigerant leakage. The air conditioner 102 is advantageous over the air conditioner 101 in terms of reducing the amount of refrigerant leakage when the rate of refrigerant leakage is high.

[0191] [Embodiment 4] Figure 11 is a schematic diagram showing an example of refrigerant flow during refrigerant leakage in the air conditioning system 103 according to Embodiment 4. The arrows indicate the flow of refrigerant. The thick lines indicate the piping range in which the refrigerant is leaking. Compared to the air conditioning system 100 of Embodiment 1, the air conditioning system 103 of Embodiment 4 differs in the configuration of one or both of the third opening / closing section 32 and the fourth opening / closing section 33. The following description will focus on the configurations in Embodiment 4 that differ from Embodiment 1, and configurations not described in Embodiment 4 are the same as in Embodiment 1.

[0192] In Embodiment 1, the third opening / closing section 32 was composed of a check valve. As mentioned above, check valves can be unstable in operation depending on the direction of pressure application. In contrast, in Embodiment 4, the third opening / closing section 32 is composed of a solenoid valve that opens when no power is applied to allow refrigerant to flow and closes when power is applied to block the flow of refrigerant. A solenoid valve can open and close the flow path regardless of the direction of pressure application. Because the third opening / closing section 32 of the air conditioner 103 is a solenoid valve, the flow of refrigerant in the third path 15 can be reliably blocked in the event of refrigerant leakage. The third opening / closing section 32 may also be an electronic expansion valve.

[0193] The air conditioning unit 103 is equipped with a battery 620 connected to a third switchgear 320. The air conditioning unit 103 has the battery 600 that was connected to the first switchgear 300 removed.

[0194] The battery 620 is a power source that drives the third switchgear 320 in the event of a power outage. The battery 620 is provided to drive the third switchgear 320 and shut off refrigerant leakage even when power is not supplied to the air conditioning unit 103. The air conditioning unit 103 can prevent refrigerant leakage in the event of a power outage by having the battery 620 connected to the third switchgear 320, thereby enhancing safety. The battery 620 has batteries 62a, 62b, and 62c corresponding to the third switchgear 32a, 32b, and 32c.

[0195] Furthermore, in the air conditioning system 100 of Embodiment 1, one or both of the first switchgear 300 and the second switchgear 310 also function as a vacuum switchgear S. In the air conditioning system 103 of Embodiment 4, one or both of the third switchgear 320 and the fourth switchgear 330 also function as a vacuum switchgear S.

[0196] The air conditioning system 103 of Embodiment 4 differs from the air conditioning system 100 of Embodiment 1 in the above configuration.

[0197] [Shut-off in case of refrigerant leak] In the event of a refrigerant leak, as shown in Figure 11, the air conditioning system 103 closes the first switchgear 300, the second switchgear 310, the third switchgear 320, and the first shut-off device 21. Here, compared to the air conditioning system 100, the third switchgear 320 in the air conditioning system 103 is composed of a solenoid valve. As a result, the air conditioning system 103 can reliably shut off the flow of refrigerant in the third path 15 compared to the air conditioning system 100. Consequently, the air conditioning system 103 can reduce the amount of refrigerant leakage compared to the air conditioning system 100.

[0198] Figure 11 shows a configuration in which only the third opening / closing section 32 is a solenoid valve, but the air conditioning system 103 is not limited to this configuration. The pressures in the third pipe 12, where the third opening / closing section 32 is provided, and the fourth pipe 11, where the fourth opening / closing section 33 is provided, fluctuate depending on the operating conditions, so the relative magnitudes of the pressures in the third pipe 12 and the fourth pipe 11 and the pressure in the liquid branch pipe 42 are not constant. Therefore, the air conditioning system 103 may be configured in which the fourth opening / closing section 33 is a solenoid valve. Alternatively, the air conditioning system 103 may be configured in which both the third opening / closing section 32 and the fourth opening / closing section 33 are solenoid valves. In short, the air conditioning system 103 includes configurations in which one or both of the third opening / closing section 32 and the fourth opening / closing section 33 are solenoid valves or electronic expansion valves.

[0199] [Vacuuming] During vacuuming, that is, when the system is not energized, the solenoid valve or electronic expansion valve constituting the third opening / closing section 32 opens, allowing the air conditioner 103 to secure a vacuum path from the third path 15. In this case, since the air conditioner 103 can secure a vacuum path from the third path 15, the battery 600 that was required when vacuuming was performed from the first path 13 becomes unnecessary.

[0200] If the fourth opening / closing section 33 is a solenoid valve or electronic expansion valve that opens when de-energized, a vacuum path can be secured from the fourth path 16. In this case, the air conditioning unit 103 can secure a vacuum path from the fourth path 16, thus eliminating the need for the battery 600 that was required when vacuuming was performed from the first path 13.

[0201] If both the third opening / closing section 32 and the fourth opening / closing section 33 are solenoid valves or electronic expansion valves that open when de-energized, then vacuum paths can be secured from the third path 15 and the fourth path 16, thus eliminating the need for the battery 600 that was required when vacuuming was performed from the first path 13.

[0202] [Effects of the air conditioning system 103 of Embodiment 4] The air conditioning system 103 provides the same effects as in Embodiment 1, and because one or both of the third opening / closing section 32 and the fourth opening / closing section 33 are composed of solenoid valves or electronic expansion valves, the following advantages are obtained compared to the case where they are composed of check valves: The air conditioning system 103 can reduce the amount of refrigerant leakage to a smaller amount compared to the air conditioning system 100.

[0203] [Embodiment 5] Figure 12 is a schematic diagram showing an example of refrigerant flow during refrigerant leakage in the air conditioning system 104 according to Embodiment 5. The arrows indicate the flow of refrigerant. The thick lines indicate the piping range in which the refrigerant is leaking. The air conditioning system 104 of Embodiment 5 differs from the air conditioning system 100 of Embodiment 1 in the configuration of the first branch section 17. The following description will focus on the configurations in Embodiment 5 that differ from those in Embodiment 1, and configurations not described in Embodiment 5 are the same as those in Embodiment 1.

[0204] The first branch section 17 has a second circuit breaker 340 that opens when de-energized and closes when energized, and the first opening / closing section 30 of the first switching device 300 is configured as an orifice-equipped solenoid valve 35. Furthermore, the battery 600 that was connected to the first switching device 300 in Embodiment 1 has been removed, and the battery 600 is now connected to the second circuit breaker 340.

[0205] In the air conditioning system 100 of Embodiment 1, one or both of the first switchgear 300 and the second switchgear 310 also served as the vacuum switchgear S. In the air conditioning system 104 of Embodiment 5, the vacuum switchgear S is configured to include a third switchgear 320 and a second shutoff device 340.

[0206] In the fifth embodiment, the vacuum switching device S has a first switching device 300 that allows the flow of air or other fluids in the first path 13 when it is not energized, and a second shut-off device 340 that shuts off the flow of refrigerant when it is energized.

[0207] The second shut-off device 340 has second shut-off valves 34a, 34b, and 34c. The second shut-off valves 34a, 34b, and 34c are composed of solenoid valves that close when energized and open when de-energized. The second shut-off valves 34a, 34b, and 34c are provided at the ends of the multiple branch pipes 10b, 10c, and 10d of the first piping 10 and at the ends of the multiple branch pipes 9b, 9c, and 9d of the second piping 9, in portions on the side of the multiple indoor units 83a, 83b, and 83c, beyond the multiple connection points that connect the multiple indoor units 83a, 83b, and 83c. The second shut-off device 340 shuts off the flow of refrigerant in both the first path 13 and the second path 14 by having the multiple second shut-off valves 34 positioned as described above.

[0208] Figure 13 is a schematic diagram of the orifice-equipped solenoid valve 35 of the air conditioning system 104 according to Embodiment 5. The arrows indicate the fluid flow. Figure 14 is an explanatory diagram of the operation of the orifice-equipped solenoid valve 35 of the air conditioning system 104 according to Embodiment 5, showing the orifice-equipped solenoid valve 35 in the open state. Figure 15 is an explanatory diagram of the operation of the orifice-equipped solenoid valve 35 of the air conditioning system 104 according to Embodiment 5, showing the orifice-equipped solenoid valve 35 in the closed state. In Figures 14 and 15, the white arrows indicate the fluid flow. The thin arrows in Figure 14 indicate the direction of the electromagnetic force. The thin arrows in Figure 15 indicate the direction of the spring force.

[0209] As shown in Figure 13, the solenoid valve with orifice 35 has an orifice 352a through which fluid flows even when the valve body 352 is closed. More specifically, as shown in Figures 14 and 15, the solenoid valve with orifice 35 includes a cylindrically formed electromagnetic coil 350 and a plunger 351 that is slidably mounted along the central axis of the electromagnetic coil 350. The solenoid valve with orifice 35 includes a valve body 352 fixed to the plunger 351 and a spring 353 that biases the valve body 352 in a direction that brings it into contact with a valve seat 354 provided in the piping 200. The valve body 352 has an orifice 352a formed by a through hole.

[0210] As shown in Figure 14, in the energized state where the electromagnetic coil 350 of the solenoid valve 35 with orifice has been energized, the electromagnetic force causes the valve body 352 to separate from the valve seat 354, allowing fluid to flow. As shown in Figure 15, in the de-energized state where the electromagnetic coil 350 has not been energized, the spring force of the spring 353 causes the valve body 352 to contact the valve seat 354, blocking the flow of fluid through the through-hole 354a provided in the valve seat 354. However, since the solenoid valve 35 with orifice has an orifice 352a formed in the valve body 352, fluid flows through the orifice 352a. In other words, the first switching device 300 has a configuration that allows fluid to flow through the orifice 352a even in the de-energized state.

[0211] The air conditioning system 104 of Embodiment 5 differs from the air conditioning system 100 of Embodiment 1 in the above configuration.

[0212] [Shut-off in case of refrigerant leak] As shown in Figure 12, when refrigerant leakage occurs, the air conditioning system 104 closes the first shut-off device 21 and the second shut-off device 340. The first switchgear 300 and the second switchgear 310 can be either open or closed, as the flow of refrigerant in the first path 13 and the second path 14 is shut off when the second shut-off device 340 is closed. In this way, the air conditioning system 104 can disconnect the indoor unit 83a with the refrigerant leak and the gas branch pipe 43a and liquid branch pipe 42a connected to the indoor unit 83a with the refrigerant leak from the other refrigerant circuits A, as in Figure 6, thereby minimizing the amount of refrigerant leakage.

[0213] [Vacuuming] Figure 16 is a schematic diagram showing an example of the airflow during vacuuming of the air conditioning system 104 according to Embodiment 5. During vacuuming, the system is de-energized, so the first shut-off device 21 and the second shut-off device 340 are open. In addition, the first opening / closing section 30 of the first opening / closing device 300 is composed of an orifice-equipped solenoid valve 35, which, as described above, allows fluid flow in the de-energized state. For this reason, the air conditioning system 104 can perform vacuuming from the first path 13, similar to Embodiment 1 shown in Figure 7.

[0214] [Effects of the air conditioning system 104 in Embodiment 5] The air conditioning system 104 includes a vacuum switching device S which comprises a first switching device 300 and a second switching device 310, both consisting of solenoid valves with orifices, and a second shut-off device 340. The air conditioning system 104 with the above configuration has a shut-off function in case of refrigerant leakage, similar to Embodiment 1, while improving the ease of installation of the air conditioning system 104 by ensuring a vacuum path.

[0215] The placement of the second shut-off valve 34 is not limited to the position shown in the figure, but may be as follows: The second shut-off valve 34 may be provided in each of the multiple branch pipes 10b, 10c, and 10d of the first piping 10. In this case, the shut-off of the second route 14 can be performed by the second switchgear 310. Alternatively, the second shut-off valve 34 may be provided in each of the multiple branch pipes 9b, 9c, and 9d of the second piping 9. In this case, the shut-off of the first route 13 can be performed by the first switchgear 300. [Explanation of Symbols]

[0216] 1 Compressor, 2 Flow path switching device, 3 Outdoor heat exchanger, 4 High-pressure side operating valve, 4b Indoor heat exchanger, 5 Low-pressure side operating valve, 6 Check valve block, 6a Check valve, 6b Check valve, 6c Check valve, 6d Check valve, 7 High-pressure pipe, 8 Low-pressure pipe, 9 Second piping, 9a Main pipe, 9b Branch pipe, 9c Branch pipe, 9d Branch pipe, 10 First piping, 10a Main pipe, 10b Branch pipe, 10c Branch pipe, 10d Branch pipe, 11 Fourth piping, 11a Main pipe, 11b Branch pipe, 11c Branch pipe, 11d Branch pipe, 12 Third piping, 12a Main pipe, 12b Branch pipe, 12c Branch pipe, 12d Branch pipe, 13 First route, 14 Second route, 15 Third route, 16 Fourth route, 17 First branch, 18 Second branch, 19 First flow control device, 20 Second flow control device, 21 First shut-off device, 22 Inlet branch, 23 Outlet junction, 24 Refrigerant leak section, 25 Vacuum pump, 30 First switch, 30a First switch, 30b First switch, 30c First switch, 31 Second switch, 31a Second switch, 31b Second switch, 31c Second switch, 32 Third switch, 32a Third switch, 32b Third switch, 32c Third switch, 33 Fourth switch, 33a Fourth switch, 33b Fourth switch, 33c Fourth switch, 33d Main pipe, 34 Second shut-off valve, 34a Second shut-off valve, 34b Second shut-off valve, 34c Second shut-off valve, 35 Solenoid valve, 40 Pressure reducing device, 40a Pressure reducing device, 40b Pressure reducing device, 40c Pressure reducing device, 41 Indoor heat exchanger, 41a Indoor heat exchanger, 41b Indoor heat exchanger, 41c Indoor heat exchanger, 42 Liquid branch pipe, 42a Liquid branch pipe, 42b Liquid branch pipe, 42c Liquid branch pipe, 43 Gas branch pipe, 43a Gas branch pipe, 43b Gas branch pipe, 43c Gas branch pipe, 50 Control device, 51 Control device, 52 Control device, 52a Control device, 52b Control device, 52c Control device, 60 Battery, 60a Battery, 60b Battery, 60c Battery, 61 Battery, 62a Battery, 62b Battery, 62c Battery, 70 Gauge manifold, 70a Low-pressure side port, 70a1 Low-pressure side meter, 70b High-pressure side port, 70b1 High-pressure side meter, 70c Supply side port, 71 High-pressure pipe service port, 72 Low-pressure pipe service port, 73 Refrigerant cylinder, 73a Valve, 74External valve, 75 Charging hose, 75a Charging hose, 75b Charging hose, 75c Charging hose, 76 External circuit, 81 Outdoor unit, 82 Repeater, 83 Indoor unit, 83a Indoor unit, 83b Non-refrigerant leaking indoor unit, 83c Indoor unit, 100 Air conditioning system, 101 Air conditioning system, 102 Air conditioning system, 103 Air conditioning system, 104 Air conditioning system, 200 Piping, 300 First switchgear, 310 Second switchgear, 320 Third switchgear, 330 Fourth switchgear, 340 Second shutoff device, 350 Electromagnetic coil, 351 Plunger, 352 Valve body, 352a Orifice, 353 Spring, 354 Valve seat, 354a Through hole, 600 Battery, 620 Battery, A Refrigerant circuit, P1 connection, S vacuum switch.

Claims

1. An outdoor unit having a compressor, an outdoor heat exchanger that performs heat exchange between outside air and refrigerant, and a flow path switching device, Multiple indoor units, each having an indoor heat exchanger that performs heat exchange between the air to be air-conditioned and the refrigerant, A relay unit located between the outdoor unit and the plurality of indoor units, which switches the flow of refrigerant supplied from the outdoor unit to the plurality of indoor units, An air conditioning system capable of simultaneous cooling and heating operation, which connects refrigerant pipes to form a refrigerant circuit, The aforementioned relay device is A first piping system comprising a first path through which refrigerant flows from the multiple indoor units to the relay unit, A first switching device provided in the first path, which individually shuts off or allows the flow of each refrigerant from the plurality of indoor units to the relay unit, A second piping system is provided, which flows refrigerant from the relay unit to the multiple indoor units, A second switching device is provided in the second path and individually shuts off or allows the flow of each refrigerant that branches off from the relay to the plurality of indoor units, A third piping system is provided, which is a third path through which refrigerant flows from the multiple indoor units to the relay unit, It consists of a fourth piping and a fourth path through which refrigerant flows from the relay unit to the multiple indoor units, A first shut-off device that opens when no power is supplied, allowing the flow of the refrigerant through the fourth path, and closes when power is supplied, thereby blocking the flow of the refrigerant through the fourth path, The system includes a vacuum switch that, when de-energized, opens to allow fluid flow in at least one of the first, second, third, and fourth paths, and when energized, closes to block the flow of refrigerant in at least one of the paths. One or both of the first and second switching devices are: It also serves as the aforementioned vacuum-pulsation switch, opening when de-energized and closing when energized. The first opening and closing device is It has a plurality of first opening / closing parts provided corresponding to the plurality of indoor units, The second opening / closing device is, It has a plurality of second opening / closing parts provided corresponding to the plurality of indoor units, An air conditioning system in which each of the plurality of first opening / closing parts and each of the plurality of second opening / closing parts is an electronic expansion valve.

2. An outdoor unit having a compressor, an outdoor heat exchanger for performing heat exchange between outside air and refrigerant, and a flow path switching device, Multiple indoor units, each having an indoor heat exchanger that performs heat exchange between the air to be air-conditioned and the refrigerant, A relay unit located between the outdoor unit and the plurality of indoor units, which switches the flow of refrigerant supplied from the outdoor unit to the plurality of indoor units, An air conditioning system capable of simultaneous cooling and heating operation, which connects refrigerant pipes to form a refrigerant circuit, The aforementioned relay device is A first piping system comprising a first path through which refrigerant flows from the multiple indoor units to the relay unit, A first switching device provided in the first path, which individually shuts off or allows the flow of each refrigerant from the plurality of indoor units to the relay unit, A second piping system is provided, which flows refrigerant from the relay unit to the multiple indoor units, A second switching device is provided in the second path and individually shuts off or allows the flow of each refrigerant that branches off from the relay to the plurality of indoor units, A third piping system is provided, which is a third path through which refrigerant flows from the multiple indoor units to the relay unit, It consists of a fourth piping and a fourth path through which refrigerant flows from the relay unit to the multiple indoor units, A first shut-off device that opens when no power is supplied, allowing the flow of the refrigerant through the fourth path, and closes when power is supplied, thereby blocking the flow of the refrigerant through the fourth path, The system includes a vacuum switch that, when de-energized, opens to allow fluid flow in at least one of the first, second, third, and fourth paths, and when energized, closes to block the flow of refrigerant in at least one of the paths. One or both of the first and second switching devices are: It also serves as the aforementioned vacuum-pulsation switch, opening when de-energized and closing when energized. The first opening and closing device is It has a plurality of first opening / closing parts provided corresponding to the plurality of indoor units, The second opening / closing device is, It has a plurality of second opening / closing parts provided corresponding to the plurality of indoor units, An air conditioning system having a configuration in which one or both of the plurality of first opening / closing sections and the plurality of second opening / closing sections are provided with two pilot-operated solenoid valves in series.

3. An outdoor unit having a compressor, an outdoor heat exchanger for performing heat exchange between outside air and refrigerant, and a flow path switching device, Multiple indoor units, each having an indoor heat exchanger that performs heat exchange between the air to be air-conditioned and the refrigerant, A relay unit located between the outdoor unit and the plurality of indoor units, which switches the flow of refrigerant supplied from the outdoor unit to the plurality of indoor units, An air conditioning system capable of simultaneous cooling and heating operation, which connects refrigerant pipes to form a refrigerant circuit, The aforementioned relay device is A first piping system comprising a first path through which refrigerant flows from the multiple indoor units to the relay unit, A first switching device provided in the first path, which individually shuts off or allows the flow of each refrigerant from the plurality of indoor units to the relay unit, A second piping system is provided, which flows refrigerant from the relay unit to the multiple indoor units, A second switching device is provided in the second path and individually shuts off or allows the flow of each refrigerant that branches off from the relay to the plurality of indoor units, A third piping system is provided, which is a third path through which refrigerant flows from the multiple indoor units to the relay unit, It consists of a fourth piping and a fourth path through which refrigerant flows from the relay unit to the multiple indoor units, A first shut-off device that opens when no power is supplied, allowing the flow of the refrigerant through the fourth path, and closes when power is supplied, thereby blocking the flow of the refrigerant through the fourth path, The system includes a vacuum switch that, when de-energized, opens to allow fluid flow in at least one of the first, second, third, and fourth paths, and when energized, closes to block the flow of refrigerant in at least one of the paths. The first piping includes a main pipe and a plurality of branch pipes that branch off from the main pipe toward the plurality of indoor units. The second piping includes a main pipe and a plurality of branch pipes branching from the main pipe toward the plurality of indoor units. The first opening / closing device has a plurality of first opening / closing parts provided on the main pipe of the first piping, The second opening / closing device has a plurality of second opening / closing parts provided on the main pipe of the second piping, It is equipped with a second circuit breaker that opens when de-energized and closes when energized, The second shut-off device has a plurality of second shut-off valves provided at the ends of the plurality of branch pipes of the first piping and the ends of the plurality of branch pipes of the second piping, in portions closer to the plurality of indoor units than the plurality of connection points that connect the plurality of indoor units corresponding to each other. Each of the plurality of first opening / closing parts and the plurality of second opening / closing parts, or one or both, is composed of an orifice-equipped solenoid valve. The vacuum switching device includes the first switching device and the second switching device, which is composed of the solenoid valve with orifice, and the second shut-off device, as well as an air conditioning system.

4. An outdoor unit having a compressor, an outdoor heat exchanger for performing heat exchange between outside air and refrigerant, and a flow path switching device, Multiple indoor units, each having an indoor heat exchanger that performs heat exchange between the air to be air-conditioned and the refrigerant, A relay unit located between the outdoor unit and the plurality of indoor units, which switches the flow of refrigerant supplied from the outdoor unit to the plurality of indoor units, An air conditioning system capable of simultaneous cooling and heating operation, which connects refrigerant pipes to form a refrigerant circuit, The aforementioned relay device is A first piping system comprising a first path through which refrigerant flows from the multiple indoor units to the relay unit, A first switching device provided in the first path, which individually shuts off or allows the flow of each refrigerant from the plurality of indoor units to the relay unit, A second piping system is provided, which flows refrigerant from the relay unit to the multiple indoor units, A second switching device is provided in the second path and individually shuts off or allows the flow of each refrigerant that branches off from the relay to the plurality of indoor units, A third piping system is provided, which is a third path through which refrigerant flows from the multiple indoor units to the relay unit, It consists of a fourth piping and a fourth path through which refrigerant flows from the relay unit to the multiple indoor units, A first shut-off device that opens when no power is supplied, allowing the flow of the refrigerant through the fourth path, and closes when power is supplied, thereby blocking the flow of the refrigerant through the fourth path, The system includes a vacuum switch that, when de-energized, opens to allow fluid flow in at least one of the first, second, third, and fourth paths, and when energized, closes to block the flow of refrigerant in at least one of the paths. The first piping includes a main pipe and a plurality of branch pipes that branch off from the main pipe toward the plurality of indoor units. The first opening / closing device is provided in the plurality of branch pipes of the first piping and has a plurality of first opening / closing sections, each consisting of an orifice-equipped solenoid valve. It is equipped with a second circuit breaker that opens when de-energized and closes when energized, The second shut-off device has a plurality of second shut-off valves provided in series with the plurality of first opening / closing units in the plurality of branch pipes of the first piping. The vacuum switching device is an air conditioning system that includes the first switching device and the second shut-off device.

5. An outdoor unit having a compressor, an outdoor heat exchanger for performing heat exchange between outside air and refrigerant, and a flow path switching device, Multiple indoor units, each having an indoor heat exchanger that performs heat exchange between the air to be air-conditioned and the refrigerant, A relay unit located between the outdoor unit and the plurality of indoor units, which switches the flow of refrigerant supplied from the outdoor unit to the plurality of indoor units, An air conditioning system capable of simultaneous cooling and heating operation, which connects refrigerant pipes to form a refrigerant circuit, The aforementioned relay device is A first piping system comprising a first path through which refrigerant flows from the multiple indoor units to the relay unit, A first switching device provided in the first path, which individually shuts off or allows the flow of each refrigerant from the plurality of indoor units to the relay unit, A second piping system is provided, which flows refrigerant from the relay unit to the multiple indoor units, A second switching device is provided in the second path and individually shuts off or allows the flow of each refrigerant that branches off from the relay to the plurality of indoor units, A third piping system is provided, which is a third path through which refrigerant flows from the multiple indoor units to the relay unit, It consists of a fourth piping and a fourth path through which refrigerant flows from the relay unit to the multiple indoor units, A first shut-off device that opens when no power is supplied, allowing the flow of the refrigerant through the fourth path, and closes when power is supplied, thereby blocking the flow of the refrigerant through the fourth path, The system includes a vacuum switch that, when de-energized, opens to allow fluid flow in at least one of the first, second, third, and fourth paths, and when energized, closes to block the flow of refrigerant in at least one of the paths. The second piping includes a main pipe and a plurality of branch pipes branching from the main pipe toward the plurality of indoor units. The second opening / closing device is provided in the plurality of branch pipes of the second piping and has a plurality of second opening / closing sections, each consisting of an orifice-equipped solenoid valve. It is equipped with a second circuit breaker that opens when de-energized and closes when energized, The second shut-off device has a plurality of second shut-off valves provided in series with the plurality of second opening / closing sections in the plurality of branch pipes of the second piping, The vacuum switching device is an air conditioning system that includes the second switching device and the second shut-off device.

6. An air conditioning system according to any one of claims 1 to 5, comprising a battery for driving the first circuit breaker in the event of a power outage.

7. The fourth piping includes a main pipe and a plurality of branch pipes that branch off from the main pipe toward the plurality of indoor units, The air conditioning apparatus according to any one of claims 1 to 5, wherein the first shutoff device is a solenoid valve provided in the main pipe of the fourth piping.

8. The fourth piping includes a main pipe and a plurality of branch pipes that branch off from the main pipe toward a plurality of indoor units. The air conditioning apparatus according to any one of claims 1 to 5, wherein the first shutoff device is composed of a plurality of solenoid valves provided in the plurality of branch pipes of the fourth piping.

9. An air conditioning system according to any one of claims 1 to 5, comprising a battery for driving the vacuum switching device in the event of a power outage.

10. The third path is provided with a third switching device that individually shuts off or allows the flow of each refrigerant from the plurality of indoor units to the relay unit, The third switching device also serves as the vacuum switching device, and opens when de-energized and closes when energized, according to claim 1 or claim 2 of the air conditioning system.

11. The third opening / closing device has a plurality of third opening / closing parts provided corresponding to the plurality of indoor units, The air conditioning device according to claim 10, wherein each of the plurality of third opening / closing parts is configured to be an electronic expansion valve or a solenoid valve.

12. The fourth path is provided with a fourth switching device that individually shuts off or allows the flow of each refrigerant branching from the relay to the plurality of indoor units, The air conditioning apparatus according to claim 1 or 2, wherein the fourth switching device also serves as the vacuum switching device, and opens when de-energized and closes when energized.

13. The fourth opening / closing device has a plurality of fourth opening / closing sections provided corresponding to the plurality of indoor units, The air conditioning device according to claim 12, wherein each of the plurality of fourth opening / closing sections is configured as an electronic expansion valve or a solenoid valve.

14. A method for vacuuming the refrigerant circuit of an air conditioning system according to any one of claims 1 to 5, A vacuuming method for performing vacuuming by driving a vacuum pump connected to a service port provided in the refrigerant circuit when the air conditioning device is not powered.

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