Air conditioning system and control method for air conditioning system

Abstract

This disclosure provides an air conditioning system that reduces the burden on workers in releasing interlocks and ensures proper interlock release. [Solution] An air conditioning system having an outdoor unit and an indoor unit that are connected to each other in a manner that enables communication between them, wherein the outdoor unit transmits an interlock release signal to the indoor unit when predetermined conditions are met, and the indoor unit includes a determination unit that determines whether a safety device that functions as a measure against refrigerant leakage is properly connected when it receives the interlock release signal from the outdoor unit, and an execution unit that, when the determination unit determines that the safety device is properly connected, sets the indoor unit to an interlock release state that permits air conditioning operation, and when the determination unit determines that the safety device is not properly connected, sets the indoor unit to an interlock state that prohibits air conditioning operation.

Description

Technical Field

[0001] The present disclosure relates to an air conditioner and a control method for an air conditioner.

Background Art

[0002] Patent Document 1 discloses an air conditioner that includes a plurality of indoor units that interlock with a safety device for refrigerant leakage countermeasures, and determines whether air conditioning operation is possible based on the state of the interlock release operation of each indoor unit.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The present disclosure provides an air conditioner and a control method for an air conditioner that reduce the burden of interlock release by an operator and enable proper interlock release.

Means for Solving the Problems

[0005] The air conditioner in the present disclosure is an air conditioner having an outdoor unit and an indoor unit connected to be communicable with each other, wherein the outdoor unit transmits an interlock release signal to the indoor unit when a predetermined condition is satisfied, and the indoor unit includes a determination unit that determines whether a safety device that functions as a refrigerant leakage countermeasure is properly connected when receiving the interlock release signal from the outdoor unit, and an execution unit that sets an interlock release state that permits air conditioning operation of the indoor unit when the determination unit determines that the safety device is properly connected, and sets an interlock state that prohibits air conditioning operation of the indoor unit when the determination unit determines that the safety device is not properly connected.

[0006] The control method for an air conditioning system in this disclosure is a control method for an air conditioning system having an outdoor unit and an indoor unit that are connected to each other in a manner that enables communication, and includes: a transmission step in which the outdoor unit transmits an interlock release signal to the indoor unit when predetermined conditions are met; a determination step in which, when the indoor unit receives the interlock release signal from the outdoor unit, it determines whether a safety device that functions as a measure against refrigerant leakage is properly connected; and an execution step in which, if the determination step determines that the safety device is properly connected, the indoor unit is set to an interlock release state that permits air conditioning operation, and if the determination step determines that the safety device is not properly connected, the indoor unit is set to an interlock state that prohibits air conditioning operation. [Effects of the Invention]

[0007] The air conditioning system and control method for the air conditioning system disclosed herein reduce the burden on operators in releasing interlocks and enable proper release of interlocks. [Brief explanation of the drawing]

[0008] [Figure 1] Diagram showing the overall configuration of the air conditioning system in Embodiment 1. [Figure 2] This diagram shows the configuration of the control unit between the outdoor unit and the indoor unit in Embodiment 1. [Figure 3] Diagram showing the arrangement of the connection part of the high-voltage switch in Embodiment 1. [Figure 4] Flowchart showing the process of releasing the interlock of the indoor unit in Embodiment 1 [Figure 5] Diagram showing the procedure for installing the air conditioning system in Embodiment 1. [Figure 6] Diagram showing the overall configuration of the air conditioning system in Embodiment 2. [Figure 7] Flowchart showing the process of releasing the interlock of the indoor unit in Embodiment 2 [Modes for carrying out the invention]

[0009] (Knowledge and other information that formed the basis of this disclosure)

[0010] At the time the present inventors conceived of this disclosure, a type of air conditioning system was known, described in Patent Document 1 and others, which includes a safety device for preventing refrigerant leakage and multiple indoor units with interlocks, and which determines whether or not to operate the air conditioning system based on the status of the interlock release operation of each indoor unit. The above-mentioned air conditioning system had the problem of requiring workers to manually release the interlock for each indoor unit, which placed a heavy burden on the workers.

[0011] On the other hand, an air conditioning system has been proposed that acts as an interlock when the safety device is not connected. While the above-mentioned air conditioning system reduces the burden on workers, there was room for improvement in safety. Therefore, this disclosure provides an air conditioning system and a control method for the air conditioning system that reduce the burden on operators in releasing interlocks and enable proper interlock release.

[0012] The embodiments will be described in detail below with reference to the drawings. However, unnecessary details may be omitted. For example, detailed explanations of already well-known matters or redundant explanations of substantially identical configurations may be omitted. This is to avoid the following explanation becoming unnecessarily verbose and to facilitate understanding for those skilled in the art. The attached drawings and the following description are provided to enable those skilled in the art to fully understand this disclosure and are not intended to limit the subject matter described in the claims.

[0013] The air conditioning system 1 according to this embodiment will be described below with reference to Figures 1-7. The air conditioning system 1 according to this embodiment includes the air conditioning system 1A according to Embodiment 1 and the air conditioning system 1B according to Embodiment 2. The air conditioner 1A according to Embodiment 1 will be described with reference to FIGS. 1 to 5. The air conditioner 1B according to Embodiment 2 will be described with reference to FIGS. 6 to 7.

[0014] (Embodiment 1) [1-1. Configuration] [1-1-1. Configuration of the air conditioner] First, referring to FIG. 1, the overall configuration of the air conditioner 1A in Embodiment 1 will be described. FIG. 1 is a diagram showing the overall configuration of the air conditioner 1A in Embodiment 1. As shown in FIG. 1, the air conditioner 1A includes one outdoor unit 10 and three indoor units 50 (indoor unit 50A, indoor unit 50B, and indoor unit 50C) connected in parallel to the outdoor unit 10 by refrigerant pipes 2. Note that the number of indoor units 50 may be one, two, or four or more.

[0015] In the air conditioner 1A, the outdoor unit 10, the indoor unit 50, and the refrigerant pipes 2 constitute a refrigeration cycle 5. The air conditioner 1A circulates the refrigerant compressed by the outdoor unit 10 between the outdoor unit 10 and the indoor unit 50 via the refrigerant pipes 2 to air-condition the room in which the indoor unit 50 is installed. In Embodiment 1, the case where the air conditioner 1A uses a flammable refrigerant as the refrigerant is exemplified. The flammable refrigerant is, for example, R32. Note that the refrigerant may be a mixed refrigerant containing 70% by weight or more of R32, propane, or a mixed refrigerant containing propane. Further, the refrigerant is not limited to a flammable refrigerant and may be a non-flammable refrigerant. For example, when the air conditioner 1A uses a flammable refrigerant as the refrigerant, it is necessary to install a safety device 6 that functions as a refrigerant leakage countermeasure. The safety device 6 will be further described with reference to FIG. 2.

[0016] Before use, the indoor unit 50 is in an interlock state in which air-conditioning operation is prohibited. The operator W who installs the air conditioner 1A needs to confirm that the indoor unit 50 is properly installed and release the interlock of the indoor unit 50. In order to facilitate the work of the operator W to release the interlock of the indoor unit 50, the air conditioner 1A of the present disclosure is configured to be able to release the interlocks of the respective indoor units 50 collectively by operating the outdoor unit 10. Details of such a configuration will be described later.

[0017] The outdoor unit 10 includes a compressor 11, a gas-liquid separator 12, an oil separator 13, a four-way valve 14, an outdoor heat exchanger 16 having an outdoor fan 15, and an outdoor expansion valve 17. On the suction side of the compressor 11, a gas-liquid separator 12 for supplying gas refrigerant to the compressor 11 is connected, and on the discharge side of the compressor 11, a four-way valve 14 is connected via an oil separator 13. On the discharge side of the compressor 11, a high-pressure switch 18 that operates when the pressure in the refrigerant pipe 2 is a predetermined value or more is provided. The outdoor heat exchanger 16 is connected to the four-way valve 14. In the outdoor heat exchanger 16, heat exchange is performed between the air sent by the outdoor fan 15 and the refrigerant flowing through the outdoor heat exchanger 16. An outdoor expansion valve 17 is connected to the downstream side of the outdoor heat exchanger 16.

[0018] The outdoor unit 10 includes an outdoor unit control unit 20 that controls the operation of the outdoor unit 10. The outdoor unit control unit 20 controls the operations of the compressor 11, the four-way valve 14, the outdoor fan 15, the outdoor expansion valve 17, and the like. In addition, a high-pressure switch 18 is connected to the outdoor unit control unit 20. The state of the high-pressure switch 18 is detected by the outdoor unit control unit 20.

[0019] The outdoor unit control unit 20 is connected to an indoor unit control unit 60 provided in each indoor unit 50 and controlling the operation of the indoor unit 50 via a communication line 3. The outdoor unit control unit 20 communicates with the indoor unit control unit 60 via the communication line 3. A plurality of indoor units 50 are connected to the outdoor expansion valve 17 and the four-way valve 14 via a refrigerant pipe 2.

[0020] Each of the multiple indoor units 50 is equipped with an indoor heat exchanger 52, an indoor expansion valve 53, a temperature sensor 54, a humidity sensor 55, and a refrigerant sensor 56, and is connected to an alarm 57 in a communicative manner. The indoor heat exchanger 52 is equipped with an indoor fan 51. The temperature sensor 54 detects the temperature of the room in which the indoor unit 50 is installed. The humidity sensor 55 detects the humidity of the room in which the indoor unit 50 is installed. The refrigerant sensor 56 detects refrigerant leakage. The alarm 57 outputs an alarm when the refrigerant sensor 56 detects refrigerant leakage. The alarm 57 is installed on the wall or the like in the air-conditioned space. The refrigerant sensor 56 constitutes part of the "safety device". Alarm device 57 constitutes part of the "safety device".

[0021] The alarm device 57 includes, for example, a buzzer and multiple LEDs (Light Emitting Diodes). The refrigerant sensor 56 may be installed on the wall of the air-conditioned space, etc. In addition, each of the multiple indoor units 50 is connected to a remote control 90 that provides instructions for starting and stopping air conditioning operation, setting the air conditioning temperature, displaying the operating status, etc.

[0022] The indoor expansion valve 53 is installed in the liquid-side piping upstream of the indoor heat exchanger 52. The indoor heat exchanger 52 is provided with a first shut-off valve 80 and a second shut-off valve 81 at both ends, which switch between a state in which the refrigerant flows and a state in which the flow of the refrigerant is blocked.

[0023] The indoor unit control unit 60 controls the operation of the first shut-off valve 80, the second shut-off valve 81, the indoor fan 51, etc. Detection signals from the temperature sensor 54, the humidity sensor 55, and the refrigerant sensor 56 are input to the indoor unit control unit 60. Based on the detection signals from the temperature sensor 54, the humidity sensor 55, and the refrigerant sensor 56, the indoor unit control unit 60 detects the temperature, humidity, and presence or absence of refrigerant leakage in the room where the indoor unit 50 is installed. The first shut-off valve 80 and the second shut-off valve 81 correspond to examples of "shut-off valves". In the following explanation, the first shut-off valve 80 and the second shut-off valve 81 may be referred to as shut-off valve 8. The shut-off valve 8 constitutes part of the "safety device".

[0024] [1-1-2. Control System Configuration] Next, with reference to Figure 2, the configuration of the control system of the air conditioning system 1A will be described. Figure 2 is a diagram showing the configuration of the control unit between the outdoor unit 10 and the indoor unit 50 in Embodiment 1. Figure 2 shows only one of the three indoor units 50 (indoor unit 50A, indoor unit 50B, and indoor unit 50C) shown in Figure 1, for the sake of explanation. The configuration and operation of each of the multiple indoor units 50 are identical to each other. The outdoor unit 10 is shipped from the factory to the installation site with the power plug unplugged from the outlet, and the installation work of the outdoor unit 10 begins while the power plug remains unplugged from the outlet.

[0025] The high-pressure switch 18 has an output contact 181 that, depending on the pressure in the refrigerant piping 2 near the discharge section of the compressor 11 where the high-pressure switch 18 is located, becomes a short-circuit state TS when the pressure is below a predetermined value, and becomes an open state TQ when the pressure exceeds a predetermined value. Both ends of the output contact 181 are connected, one at a time, to the connection terminals 221 and 222 of the socket 22 provided on the outdoor unit control unit 20, via a plug 182. As shown in Figure 2, when a high-voltage switch 18, in which the output contact 181 is in a short-circuit state TS, is connected to the socket 22, the connection terminals 221 and 222 become short-circuited TS. When the high-voltage switch 18 is not connected to the connector, the connection terminals 221 and 222 become open TQ.

[0026] Next, the effect of using the high-voltage switch 18 as an interlock release component will be explained. The high-voltage switch 18 is connected to the power relay for driving the compressor 11. More specifically, the high-voltage switch 18 is connected to the circuit that drives the coil that drives the power relay for starting the compressor 11. Therefore, if the high-pressure switch 18 is not connected to the socket 22, the power relay will be in the open state TQ, and the compressor 11 cannot be driven. If a component not connected to the power relay (e.g., various sensors such as temperature sensors and pressure sensors) is used as a component for releasing the interlock, the compressor 11 may be driven even if the component is not connected, due to design errors in the control specifications or control software of the air conditioning system 1A.

[0027] On the other hand, as in Embodiment 1, by using the high-voltage switch 18 connected to the power relay as a component for releasing the interlock, it is possible to physically restrict the start of operation of the compressor 11 even if there is a design error in the software. Therefore, even when the high-voltage switch 18 is not inserted (in other words, when the safety device has not been inspected), it is possible to prevent the compressor 11 from operating, thereby improving safety. Furthermore, the power relay to which the high-pressure switch 18 is connected is used to drive the compressor 11 and is therefore high-voltage, and could potentially become an ignition source. By inserting the high-pressure switch 18 after the operator has confirmed that there is no refrigerant leak in the outdoor unit 10 in addition to the safety devices, it is possible to suppress ignition by the power relay in the event that refrigerant leaks inside the outdoor unit 10 and the air conditioning is operated.

[0028] As shown in Figure 2, the outdoor unit 10 is equipped with an outdoor unit control unit 20 that controls the operation of the outdoor unit 10. The outdoor unit control unit 20 includes an outdoor unit communication circuit 21, an outdoor unit processor 30, an outdoor unit memory 35, and a socket 22 to which a high-voltage switch 18 is connected.

[0029] The outdoor unit communication circuit 21 communicates with the indoor unit communication circuit 61 according to instructions from the outdoor unit processor 30. For example, the outdoor unit communication circuit 21 sends an interlock release signal SGU to the indoor unit communication circuit 61.

[0030] The outdoor unit processor 30 is a processor such as a CPU (Central Processing Unit) or MPU (Micro Processing Unit).

[0031] The outdoor unit memory 35 is a memory that stores programs and data. The outdoor unit memory 35 stores the outdoor unit program 36. The outdoor unit memory 35 has a non-volatile storage area. Alternatively, the outdoor unit memory 35 may also have a volatile storage area and constitute the work area of ​​the outdoor unit processor 30. The outdoor unit memory 35 is composed of, for example, ROM (Read Only Memory) or RAM (Random Access Memory).

[0032] The outdoor unit processor 30 controls the operation of the outdoor unit 10 by reading and executing the outdoor unit program 36 stored in the outdoor unit memory 35, and functions as a state detection unit 31 and a transmission unit 32.

[0033] The state detection unit 31 detects whether the connection terminals 221 and 222 of the socket 22 are in a short-circuit state (TS) or an open-circuit state (TQ). In the following explanation, for convenience, a short-circuit state TS between connection terminals 221 and 222 of socket 22 may be simply referred to as "short-circuit state TS". Similarly, an open-circuit state TQ between connection terminals 221 and 222 of socket 22 may be simply referred to as "open-circuit state TQ".

[0034] The transmitting unit 32 transmits an interlock release signal SGU to the indoor unit 50 when predetermined conditions are met. For example, the transmitting unit 32 transmits the interlock release signal SGU to the indoor unit 50 when the power to the outdoor unit 10 is turned on while the unit is in the open state TQ. The fact that the power to the outdoor unit 10 is turned on while the gate is in the open state TQ corresponds to one example of a "predetermined condition". The interlock release signal SGU is a signal that instructs the indoor unit 50 to release the interlock.

[0035] Furthermore, the transmitter 32 terminates the transmission of the interlock release signal SGU to the indoor units 50 when it receives release response signals from all indoor units 50. The release response signal indicates that the interlock release process has been completed in the indoor unit 50. For example, the release response signal indicates that the release flag 77 stored in the indoor unit memory 75 has changed from "0" (interlock state STL) to "1" (interlock release state STU).

[0036] As shown in Figure 2, the indoor unit 50 is equipped with an indoor unit control unit 60 that controls the operation of the indoor unit 50. The indoor unit control unit 60 includes an indoor unit communication circuit 61 connected to the outdoor unit communication circuit 21 by a communication line 3, an indoor unit processor 70, and an indoor unit memory 75.

[0037] The indoor unit communication circuit 61 communicates with the outdoor unit communication circuit 21 according to instructions from the indoor unit processor 70. For example, the indoor unit communication circuit 61 receives an interlock release signal SGU from the outdoor unit communication circuit 21.

[0038] The indoor unit processor 70 is a processor such as a CPU or MPU. The indoor unit memory 75 is a memory that stores programs and data. The indoor unit memory 75 stores the indoor unit program 76. The indoor unit memory 75 has a non-volatile storage area. The indoor unit memory 75 may also have a volatile storage area and constitute the work area of ​​the indoor unit processor 70. The indoor unit memory 75 is composed of, for example, ROM or RAM.

[0039] The indoor unit processor 70 functions as a release reception unit 71, a determination unit 72, and an execution unit 73 by reading and executing the indoor unit program 76. The release reception unit 71 receives an instruction to release the interlock for the indoor unit 50 when the indoor unit communication circuit 61 receives the interlock release signal SGU transmitted from the outdoor unit 10.

[0040] When the release receiving unit 71 receives an interlock release signal SGU from the outdoor unit 10, the determination unit 72 determines whether the safety device 6, which functions as a refrigerant leak prevention measure, is properly connected. "Properly connected" means, for example, that it is connected in a way that allows it to communicate with the indoor unit control unit 60. The safety device 6 includes, for example, shut-off valves 8 (i.e., a first shut-off valve 80 and a second shut-off valve 81), a refrigerant sensor 56, and an alarm 57.

[0041] If the safety device 6 is properly connected, the shut-off valve 8, refrigerant sensor 56, and alarm 57 each transmit a connection signal SGC to the indoor unit control unit 60 indicating that they are properly connected. Each of the shut-off valve 8, refrigerant sensor 56, and alarm device 57 is pre-assigned a unique address. The connection signal SGC includes the addresses corresponding to each of the shut-off valve 8, refrigerant sensor 56, and alarm device 57.

[0042] The shut-off valve 8 transmits a connection signal SGC, which includes a unique address assigned to the shut-off valve 8, to the indoor unit control unit 60. The refrigerant sensor 56 transmits a connection signal SGC, which includes a unique address assigned to the refrigerant sensor 56, to the indoor unit control unit 60. The alarm device 57 transmits a connection signal SGC, which includes a unique address assigned to the alarm device 57, to the indoor unit control unit 60.

[0043] When the release receiving unit 71 receives an interlock release signal SGU from the outdoor unit 10, the determination unit 72 first determines whether the shut-off valve 8 is properly connected. The determination unit 72 determines that the shut-off valve 8 is properly connected if it receives a connection signal SGC that includes a unique address assigned to the shut-off valve 8. The determination unit 72 determines that the shut-off valve 8 is not properly connected if it does not receive a connection signal SGC that includes a unique address assigned to the shut-off valve 8.

[0044] Then, if the determination unit 72 determines that the shut-off valve 8 is properly connected, the determination unit 72 determines whether the refrigerant sensor 56 and the alarm 57 are properly connected. If the determination unit 72 determines that at least one of the refrigerant sensor 56 and the alarm 57 is not properly connected, the determination unit 72 determines that the safety device 6 is not properly connected.

[0045] The determination unit 72 determines that the safety device 6 is not properly connected if it does not receive a connection signal SGC from at least one of the refrigerant sensor 56 and the alarm 57 within a predetermined period PT from the time it receives a connection signal SGC from the shut-off valve 8. The predetermined period PT is, for example, "3 minutes". Furthermore, the determination unit 72 determines, for example, that the safety device 6 is not properly connected if the alarm 57 is properly connected but the refrigerant sensor 56 is not properly connected.

[0046] The execution unit 73 sets the indoor unit 50 to an interlock release state, which permits air conditioning operation, when the release reception unit 71 receives an instruction to release the interlock for the indoor unit 50 and the determination unit 72 determines that the safety device 6 is properly connected. The execution unit 73 changes the release flag 77 stored in the indoor unit memory 75 from "0" (interlock state STL) to "1" (interlock release state STU) when the release reception unit 71 receives an instruction to release the interlock for the indoor unit 50 and the determination unit 72 determines that the safety device 6 is properly connected. The release flag 77 indicates whether or not the interlock release state STU is in effect.

[0047] The release flag 77 is stored in a non-volatile memory area of ​​the indoor unit memory 75. For example, the release flag 77 is stored in the EEPROM (Electrically Erasable Programmable Read-Only Memory) of the indoor unit memory 75.

[0048] Furthermore, the execution unit 73 changes the release flag 77 from "0" (interlock state STL) to "1" (interlock release state STU) and then sends a release response signal to the outdoor unit 10. The release response signal indicates that the interlock release process has been completed in the indoor unit 50. The release flag 77 in state "1" corresponds to an example of "interlock release information".

[0049] When the release flag 77 is "0", the execution unit 73 sets the indoor unit 50 to an interlock state STL, which prohibits air conditioning operation. Furthermore, when the release flag 77 is "1", the execution unit 73 sets the interlock release state STU to allow air conditioning operation of the indoor unit 50.

[0050] When the release reception unit 71 receives an instruction to release the interlock for the indoor unit 50, and the determination unit 72 determines that the safety device 6 is not properly connected, the execution unit 73 causes the remote control 90 to notify error information in a manner that allows the identification of the device among the components of the safety device 6 that is not properly connected.

[0051] The remote control 90 has, for example, a red LED and a green LED. For example, if the shut-off valve 8 is not properly connected, the remote control 90 will flash a red LED. Also, for example, if the alarm 57 is not properly connected, the remote control 90 will light up a red LED. Also, for example, if the refrigerant sensor 56 is not properly connected, the remote control 90 will flash a green LED. If the safety device 6 is properly connected, the remote control 90 will illuminate a green LED.

[0052] In Embodiment 1, when the release reception unit 71 receives an instruction to release the interlock for the indoor unit 50, and the determination unit 72 determines that the safety device 6 is not properly connected, the execution unit 73 causes the remote control 90 corresponding to each of the indoor units 50A, 50B, and 50C to notify error information in a manner that allows identification of the device that is not properly connected among the devices constituting the safety device 6. However, the embodiments are not limited to this. For example, if the indoor unit control unit 60 is connected to a terminal device such as a personal computer or tablet device in a communicative manner, the execution unit 73 may cause the terminal device to notify error information in a manner that allows for the identification of the safety devices 6 that are not properly connected among the safety devices 6 corresponding to each of the indoor units 50A, 50B, and 50C, and the equipment constituting the safety device 6 that is not properly connected. The equipment constituting the safety device 6 is a shut-off valve 8, a refrigerant sensor 56, and an alarm 57.

[0053] [1-1-3. Configuration of High-Voltage Switches] Next, with reference to Figure 3, the arrangement of the connection parts of the high-voltage switch 18 in Embodiment 1 will be described. Figure 3 is a diagram showing the arrangement of the connection parts of the high-voltage switch 18 in Embodiment 1. Figure 3 illustrates the layout of the circuit board 100 on which the electronic components of the outdoor unit control unit 20 are mounted. The mounting area of ​​the circuit board 100 is divided into a high-voltage area 110 where high-voltage (e.g., 200-300V) electronic components (such as electrolytic capacitors 111) are mounted, and a low-voltage area 120 where low-voltage (e.g., 12V) electronic components are mounted.

[0054] The socket 22 to which the high-voltage switch 18 is connected is mounted in the low-voltage area 120. This prevents worker W from accidentally touching electronic components mounted in the high-voltage area 110 when connecting the plug 182 of the high-voltage switch 18 to the socket 22. Note that the socket 22 only needs to be located away from the high-voltage area 110, and the high-voltage area 110 and the low-voltage area 120 do not need to be completely separated.

[0055] [1-2. Operation] [1-2-1. Interlock release process] Next, with reference to Figure 4, the procedure for releasing the interlock of the indoor unit 50, which is performed by the outdoor unit 10 and the indoor unit 50, will be described. Figure 4 is a flowchart showing the process for releasing the interlock of the indoor unit 50 in Embodiment 1. The outdoor unit 10 and the indoor unit 50 execute the process shown in the flowchart in Figure 4 during initial communication after power-on, or when periodic communication is performed to exchange information between the outdoor unit 10 and the indoor unit 50.

[0056] Steps S101 to S107 in Figure 4 are processes performed by the outdoor unit control unit 20 of the outdoor unit 10, and steps S201 to S215 are processes performed by the indoor unit control unit 60 of the indoor unit 50. Each of the multiple indoor units 50 (indoor units 50A, 50B, and 50C shown in Figure 1) executes the processes of steps S201 to S215 shown in Figure 4.

[0057] The outdoor unit control unit 20 of the outdoor unit 10 executes the processes of steps S101 to S103. First, in step S101, the transmitting unit 32 determines whether the power to the outdoor unit 10 has been turned on in a short-circuit state TS. In other words, the transmitting unit 32 determines whether the "predetermined conditions" are met.

[0058] If the transmitter 32 determines that the outdoor unit 10 is not powered on in a short-circuit state TS (step S101; NO), the process enters a standby state. If the transmitter 32 determines that the outdoor unit 10 is powered on in a short-circuit state TS (step S101; YES), the process proceeds to step S103. Then, in step S103, the transmitting unit 32 transmits an interlock release signal SGU to the indoor unit 50.

[0059] Next, the indoor unit control unit 60 of the indoor unit 50 executes the processes from steps S201 to S215. In step S201, the release reception unit 71 determines whether or not it has received the interlock release signal SGU transmitted from the outdoor unit 10. If the release reception unit 71 determines that it has not received the interlock release signal SGU transmitted from the outdoor unit 10 (step S201; NO), the process enters a standby state. If the release reception unit 71 determines that it has received the interlock release signal SGU transmitted from the outdoor unit 10 (step S201; YES), the process proceeds to step S203.

[0060] Then, in step S203, the determination unit 72 determines whether or not it has received a connection signal SGC from the shut-off valve 8. If the determination unit 72 determines that it has not received a connection signal SGC from the shut-off valve 8 (step S203; NO), the process enters a standby state. If the determination unit 72 determines that it has received a connection signal SGC from the shut-off valve 8 (step S203; YES), the determination unit 72 determines that the shut-off valve 8 is properly connected, and the process proceeds to step S205.

[0061] Then, in step S205, the determination unit 72 determines whether or not it has received a connection signal SGC from the alarm device 57. If the determination unit 72 determines that it has not received a connection signal SGC from the alarm device 57 (step S205; NO), the process proceeds to step S209. If the determination unit 72 determines that it has received a connection signal SGC from the alarm device 57 (step S205; YES), the determination unit 72 determines that the alarm device 57 is properly connected, and the process proceeds to step S207.

[0062] Then, in step S207, the determination unit 72 determines whether or not it has received a connection signal SGC from the refrigerant sensor 56. If the determination unit 72 determines that it has received a connection signal SGC from the refrigerant sensor 56 (step S207; YES), the determination unit 72 determines that the refrigerant sensor 56 is properly connected, and the process proceeds to step S213. If the determination unit 72 determines that it has not received a connection signal SGC from the refrigerant sensor 56 (step S207; NO), the process proceeds to step S209.

[0063] If the answer is NO in step S205 and NO in step S207, then in step S209, the determination unit 72 determines whether a predetermined period PT has elapsed since the connection signal SGC was received from the shut-off valve 8. If the determination unit 72 determines that the predetermined period PT has not elapsed (step S209; NO), the process returns to step S205. If the determination unit 72 determines that the predetermined period PT has elapsed (step S209; YES), the process proceeds to step S211. Then, in step S211, the execution unit 73 causes the remote control 90 to notify error information in a manner that allows it to identify which of the devices constituting the safety device 6 is not properly connected. In this case, the indoor unit 50 maintains the interlock state. After that, the process ends.

[0064] If the answer in step S207 is YES, in step S213, the execution unit 73 determines that the safety device 6 is properly connected and changes the release flag 77 from "0" (interlock state STL) to "1" (interlock release state STU). Also, when the release flag 77 is changed to "1", the execution unit 73 sets the indoor unit 50 to the interlock release state STU, which allows air conditioning operation. Next, in step S215, the execution unit 73 sends a release response signal to the outdoor unit 10. After that, the processing of the indoor unit control unit 60 of the indoor unit 50 is completed. The release response signal indicates that the interlock release process has been completed in the indoor unit 50.

[0065] Next, the outdoor unit control unit 20 of the outdoor unit 10 executes the processes from steps S105 to S107. First, in step S105, the transmitting unit 32 determines whether or not it has received a release response signal from all indoor units 50. Furthermore, if an indoor unit 50 is added or replaced, "all indoor units 50" in step S105 refers to all indoor units 50 that have been added or replaced. If the transmitter 32 determines that it has not received a release response signal from all indoor units 50 (step S105; NO), the process enters a standby state. If the transmitter 32 determines that it has received a release response signal from all indoor units 50 (step S105; YES), the process proceeds to step S107.

[0066] Then, in step S107, the transmitting unit 32 terminates the transmission of the interlock release signal SGU to the indoor unit 50. After that, the processing of the outdoor unit control unit 20 of the outdoor unit 10 is terminated.

[0067] Steps S101 to S103 correspond to an example of the "transmission step". Steps S201 to S207 correspond to an example of a "judgment step". Step S213 corresponds to an example of an "execution step".

[0068] In the flowchart shown in Figure 4, the condition for ending transmission of the interlock release signal SGU by the transmitter 32 is that release response signals have been received from all indoor units 50. However, the conditions for ending transmission of the interlock release signal SGU are not limited to this. The conditions for ending the transmission of the interlock release signal SGU by the transmitting unit 32 may include, for example, receiving release response signals from all indoor units 50, as well as other conditions such as the following first, second, and third conditions.

[0069] Condition 1: When a predetermined period of time has elapsed since the transmission of the interlock release signal SGU, the transmission of the interlock release signal SGU is terminated. Second condition: When the indoor unit 50 is installed and each step of the trial operation is performed, if the trial operation starts without any problems, the transmission of the interlock release signal SGU is terminated. Third condition: When the predetermined process (circuit inspection process, etc.) before installing the indoor unit 50 and performing a trial run is completed, the transmission of the interlock release signal SGU is terminated. In this case, if there is an indoor unit 50 that has not received the interlock release signal SGU due to some malfunction, an error will be triggered during the trial run, so the worker W will be able to notice that the interlock of the indoor unit 50 has not been released.

[0070] [1-2-2. Installation Procedure for Air Conditioning Systems] Next, the installation procedure for the air conditioning system 1A will be described with reference to the process chart shown in Figure 5. Figure 5 is a diagram showing the procedure for installing the air conditioning system 1A in Embodiment 1. The schedule shown in Figure 5 is for the case of newly installing the air conditioning system 1A and the case of replacing the outdoor unit 10. Note that Figure 5 explains the case where the safety device 6 is properly connected.

[0071] In the process chart shown in Figure 5, in the first step, worker W installs the outdoor unit 10 and the indoor unit 50, and installs safety devices 6 (refrigerant sensor 56, alarm 57, shut-off valves 80, 81, etc.) to deal with refrigerant leakage, and then performs the work in steps 2 to 8. In the first step, as shown in Figure 5, the plug 182 of the high-voltage switch 18 on the outdoor unit 10 is not connected to the socket 22 of the outdoor unit control unit 20. That is, the high-voltage switch 18 is in the OFF state. Also, the outdoor unit 10 is not communicating with the indoor unit 50 on a regular basis. Furthermore, the alarm indicating that the outdoor unit 10 is interlocked is in the ON state, i.e., it is in an output-enabled state.

[0072] Next, in the ninth step, worker W unlocks the interlock of the outdoor unit 10 by connecting the plug 182 of the high-voltage switch 18 to the socket 22 of the outdoor unit control unit 20. Furthermore, since the plug 182 of the high-voltage switch 18 is connected to the socket 22 of the outdoor unit control unit 20, the high-voltage switch 18 becomes ON, i.e., operational. Here, we will explain the case where the pressure in the refrigerant piping 2, as explained with reference to Figure 2, is below a predetermined value. In this case, the high-pressure switch 18 enters a short-circuit state TS.

[0073] Next, in the tenth step, worker W turns on the power to the outdoor unit 10. Furthermore, since the plug 182 of the high-voltage switch 18 is connected to the socket 22 of the outdoor unit control unit 20, the state detection unit 31 of the outdoor unit control unit 20 of the outdoor unit 10 detects a short-circuit state TS. As a result, the "predetermined conditions" described with reference to Figure 2 are met. As described above, worker W performs steps 9 and 10 to release the interlock of the indoor unit 50.

[0074] Next, in the 11th step, worker W configures the communication settings between the outdoor unit 10 and the indoor unit 50, and establishes a communication connection between the outdoor unit 10 and the indoor unit 50. Next, in step 12, the outdoor unit communication circuit 21 starts periodic communication with the indoor unit communication circuit 61. At this time, the transmitting unit 32 transmits an interlock release signal SGU to the indoor unit 50. Next, in the 13th step, the release reception unit 71 of the indoor unit control unit 60 of the indoor unit 50 receives the interlock release signal SGU transmitted from the outdoor unit 10 and receives an instruction to release the interlock for the indoor unit 50. Then, because the safety device 6 is properly connected, the execution unit 73 changes the release flag 77 stored in the indoor unit memory 75 from "0" (interlock state STL) to "1" (interlock release state STU). The release flag 77 indicates whether or not the interlock release state STU is active. The execution unit 73 also sets the indoor unit 50 to the interlock release state STU, which allows for air conditioning operation. In this way, the interlock of the indoor unit 50 is released.

[0075] Next, in step 14, a circuit inspection is performed. The circuit inspection checks whether the first shut-off valve 80, the second shut-off valve 81, and the alarm 57, which are safety devices in case of refrigerant leakage, are functioning correctly. For example, the alarm 57 is tested to see if it emits an error alarm correctly, or whether the first shut-off valve 80 and the second shut-off valve 81 open and close correctly. Next, in step 15, worker W uses remote control 90 to deactivate the error alarm of alarm device 57. Next, in step 16, worker W performs a test run of the air conditioning system 1A, and in step 17, safety measures are completed and the installation work of the air conditioning system 1A is completed.

[0076] [1-3. Effects, etc.] As described above, in Embodiment 1, the air conditioning system 1A is an air conditioning system 1 having an outdoor unit 10 and an indoor unit 50 that are connected to each other in a manner that allows them to communicate with each other. The outdoor unit 10 transmits an interlock release signal SGU to the indoor unit 50 when predetermined conditions are met. The indoor unit 50 includes a determination unit 72 that determines whether a safety device 6, which functions as a measure against refrigerant leakage, is properly connected when it receives the interlock release signal SGU from the outdoor unit 10. The indoor unit 50 includes an execution unit 73 that sets the indoor unit 50 to an interlock release state STU, which allows air conditioning operation, when the determination unit 72 determines that the safety device 6 is properly connected, and sets the indoor unit 50 to an interlock state STL, which prohibits air conditioning operation, when the determination unit 72 determines that the safety device 6 is not properly connected.

[0077] According to the above configuration, when an interlock release signal SGU is received from the outdoor unit 10, if the safety device 6 is properly connected, the system will be in an interlock release state STU, which allows air conditioning operation of the indoor unit 50, and in an interlock state STL, which prohibits air conditioning operation of the indoor unit 50, if the safety device 6 is not properly connected. Therefore, the burden on the worker W to release the interlock is reduced, and the interlock release can be performed properly.

[0078] In the above-described air conditioning system 1A, the safety device 6 includes a shut-off valve 8 that blocks the flow of refrigerant, a refrigerant sensor 56 that detects refrigerant leakage, and an alarm 57 that outputs an alarm. The determination unit 72 determines whether the refrigerant sensor 56 and the alarm 57 are properly connected when the shut-off valve 8 is properly connected, and determines that the safety device 6 is not properly connected if it determines that at least one of the refrigerant sensor 56 and the alarm 57 is not properly connected.

[0079] According to this, the safety device 6 includes a shut-off valve 8, a refrigerant sensor 56, and an alarm 57. When the shut-off valve 8 is properly connected, it is determined whether the refrigerant sensor 56 and the alarm 57 are properly connected. If at least one of the refrigerant sensor 56 and the alarm 57 is not properly connected, it is determined that the safety device 6 is not properly connected. Therefore, it is possible to properly determine whether the safety device 6 is properly connected. Consequently, safety can be improved by suppressing air conditioning operation due to incorrect interlock release by the worker W.

[0080] In the above-described air conditioning system 1A, if the shut-off valve 8, refrigerant sensor 56, and alarm 57 are properly connected to the indoor unit 50, each of the shut-off valve 8, refrigerant sensor 56, and alarm 57 transmits a connection signal SGC to the indoor unit 50 indicating that they are properly connected. The determination unit 72 determines that the safety device 6 is not properly connected if it does not receive a connection signal SGC from at least one of the refrigerant sensor 56 and alarm 57 within a predetermined period PT from the time it receives the connection signal SGC from the shut-off valve 8.

[0081] According to this, if the connection signal SGC is not received from at least one of the refrigerant sensor 56 and the alarm 57 within a predetermined period PT from the time the connection signal SGC is received from the shut-off valve 8, it is determined that the safety device 6 is not properly connected. Therefore, by setting the predetermined period PT to an appropriate period, the burden on the worker W to release the interlock is reduced, and the interlock can be released properly.

[0082] In the above-described air conditioning system 1A, the determination unit 72 determines that the safety device 6 is not properly connected if the alarm 57 is properly connected but the refrigerant sensor 56 is not properly connected.

[0083] According to this, if the alarm 57 is properly connected but the refrigerant sensor 56 is not properly connected, it is determined that the safety device 6 is not properly connected, thus allowing for a proper determination of whether the safety device 6 is properly connected or not. Therefore, safety can be improved by suppressing air conditioning operation caused by incorrect interlock release by the worker W.

[0084] The control method for the air conditioning system 1A includes an outdoor unit 10 and an indoor unit 50 that are connected to each other in a manner that enables communication, and includes: a transmission step in which the outdoor unit 10 transmits an interlock release signal SGU to the indoor unit 50 when predetermined conditions are met; a determination step in which, when the indoor unit 50 receives the interlock release signal SGU from the outdoor unit 10, it determines whether a safety device 6 that functions as a measure against refrigerant leakage is properly connected; and an execution step in which, if the determination step determines that the safety device 6 is properly connected, the indoor unit 50 is set to an interlock release state STU that permits air conditioning operation, and if the determination step determines that the safety device 6 is not properly connected, the indoor unit 50 is set to an interlock state STL that prohibits air conditioning operation.

[0085] According to this, the control method for the air conditioning system 1A produces the same effect as the air conditioning system 1A described above.

[0086] (Embodiment 2) [2-1. Structure] [2-1-1. Configuration of the air conditioning system] Next, with reference to Figure 6, the overall configuration of the air conditioning system 1B in Embodiment 2 will be described. Figure 6 is a diagram showing the overall configuration of the air conditioning system 1B in Embodiment 2. Referring to Figure 6, the differences between the air conditioning system 1B in Embodiment 2 and the air conditioning system 1A in Embodiment 1 shown in Figure 1 will be explained.

[0087] In the first embodiment of the air conditioning system 1A shown in Figure 1, the case was described in which each indoor unit control unit 60 of the three indoor units 50 (indoor unit 50A, indoor unit 50B, and indoor unit 50C) performs the process of releasing the interlock of the indoor unit 50 and determining whether the safety device 6 is properly connected. In contrast, in the second embodiment of the air conditioning system 1B shown in Figure 6, the three indoor units 50 (indoor unit 50A, indoor unit 50B, and indoor unit 50C) are pre-configured as indoor units 50 constituting the first group GR1.

[0088] Furthermore, in the air conditioning system 1B of Embodiment 2 shown in Figure 6, multiple indoor units 50 constituting the second group GR2 (not shown) are arranged. Each of the multiple indoor units 50 constituting the second group GR2 is connected in parallel to the outdoor unit 10 by refrigerant piping 2, similar to the indoor units 50 constituting the first group GR1. Furthermore, each of the multiple indoor units 50 constituting the second group GR2, together with the outdoor unit 10 and the refrigerant piping 2, constitutes a refrigeration cycle 5. In other words, the air conditioning system 1B circulates the refrigerant compressed by the outdoor unit 10 between the outdoor unit 10 and the indoor units 50 via the refrigerant piping 2, thereby providing air conditioning for the room in which the indoor units 50 are installed.

[0089] The three indoor units 50 (indoor unit 50A, indoor unit 50B, and indoor unit 50C), as shown by the dashed lines, harmonize the air in a single target space enclosed by a wall WS, etc., in this case, a single room R1. Furthermore, of the three indoor units 50 (indoor unit 50A, indoor unit 50B, and indoor unit 50C) that make up the first group GR1, one indoor unit 50 is set as the master unit, and the other two indoor units 50 are set as slave units. Embodiment 2 describes a case where, for example, indoor unit 50A is set as the master unit, and indoor units 50B and 50C are set as slave units.

[0090] Embodiment 2 describes the case where three indoor units 50 constitute the first group GR1, but two indoor units 50 may constitute the first group GR1, or four or more indoor units 50 may constitute the first group GR1. Similarly, the multiple indoor units 50 that make up the second group GR2 can consist of two or more indoor units 50.

[0091] The indoor unit 50A, which is set as the master unit, performs the following processes for the three indoor units 50 (indoor unit 50A, indoor unit 50B, and indoor unit 50C) that make up the first group GR1: releasing the interlock of indoor unit 50 and determining whether the safety device 6 is properly connected.

[0092] [2-1-2. Control System Configuration] Referring to Figure 2, the configuration of indoor unit 50A, which is set as the master unit, and the configurations of indoor units 50B and 50C, which are set as slave units, will be explained. First, let's explain the configuration of the 50A indoor unit, which is set as the master unit. Indoor unit 50A has the same configuration as indoor unit 50 shown in Figure 2. In indoor unit 50A, for example, indoor unit processor 70 functions as a release reception unit 71, a determination unit 72, and an execution unit 73 by reading and executing indoor unit program 76.

[0093] In the indoor unit 50A, which is set as the master unit, the release reception unit 71, the determination unit 72, and the execution unit 73 each have the same functions as the release reception unit 71, determination unit 72, and execution unit 73 of the indoor unit 50 in Embodiment 1, which was described with reference to Figure 2. Furthermore, in the indoor unit 50A configured as the master unit, the release reception unit 71, the determination unit 72, and the execution unit 73 each have the following additional functions.

[0094] When the release receiving unit 71 receives an interlock release signal SGU from the outdoor unit 10, the determination unit 72 determines whether the safety device 6, which functions as a refrigerant leak prevention measure, is properly connected to the indoor units 50B and 50C.

[0095] When the release receiving unit 71 receives an interlock release signal SGU from the outdoor unit 10, the determination unit 72 first determines whether the shut-off valves 8 corresponding to each of the indoor units 50A, 50B, and 50C are properly connected. The determination unit 72 determines that the shut-off valves 8 corresponding to each of the indoor units 50A, 50B, and 50C are properly connected when it receives a connection signal SGC containing a unique address assigned to each of the shut-off valves 8 corresponding to each of the indoor units 50A, 50B, and 50C. The determination unit 72 determines that the shut-off valves 8 corresponding to each of the indoor units 50A, 50B, and 50C are not properly connected when it does not receive a connection signal SGC containing a unique address assigned to each of the shut-off valves 8 corresponding to each of the indoor units 50A, 50B, and 50C.

[0096] The determination unit 72 receives a connection signal SGC, which includes a unique address assigned to the shut-off valve 8 corresponding to the indoor unit 50B, from the determination unit 72 of the indoor unit 50B. In other words, when the determination unit 72 of the indoor unit 50B receives a connection signal SGC, which includes a unique address assigned to the shut-off valve 8, from the shut-off valve 8 corresponding to the indoor unit 50B, it forwards the connection signal SGC to the indoor unit 50A. Furthermore, the determination unit 72 receives a connection signal SGC, which includes a unique address assigned to the shut-off valve 8 corresponding to the indoor unit 50C, from the determination unit 72 of the indoor unit 50C. That is, when the determination unit 72 of the indoor unit 50C receives a connection signal SGC, which includes a unique address assigned to the shut-off valve 8, from the shut-off valve 8 corresponding to the indoor unit 50C, it forwards the connection signal SGC to the indoor unit 50A.

[0097] Then, if the determination unit 72 determines that the shut-off valves 8 corresponding to each of the indoor units 50A, 50B, and 50C are properly connected, the determination unit 72 determines whether the refrigerant sensors 56 and alarms 57 corresponding to each of the indoor units 50A, 50B, and 50C are properly connected. If the determination unit 72 determines that at least one of the refrigerant sensor 56 and alarm 57 corresponding to each of the indoor units 50A, 50B, and 50C is not properly connected, the determination unit 72 determines that the safety device 6 corresponding to each of the indoor units 50A, 50B, and 50C is not properly connected.

[0098] The determination unit 72 determines that the safety devices 6 corresponding to each of the indoor units 50A, 50B, and 50C are not properly connected if it does not receive a connection signal SGC from at least one of the refrigerant sensors 56 and alarms 57 corresponding to each of the indoor units 50A, 50B, and 50C within a predetermined period PT from the time it receives a connection signal SGC from the shut-off valve 8 corresponding to each of the indoor units 50A, 50B, and 50C. The predetermined period PT is, for example, "3 minutes". Furthermore, the determination unit 72 determines, for example, that the safety device 6 is not properly connected if the alarm devices 57 corresponding to each of the indoor units 50A, 50B, and 50C are properly connected, but the refrigerant sensors 56 corresponding to each of the indoor units 50A, 50B, and 50C are not properly connected.

[0099] The determination unit 72 receives a connection signal SGC, which includes a unique address assigned to the alarm 57 corresponding to the indoor unit 50B, from the determination unit 72 of the indoor unit 50B. In other words, when the determination unit 72 of the indoor unit 50B receives a connection signal SGC, which includes a unique address assigned to the alarm 57, from the alarm 57 corresponding to the indoor unit 50B, it forwards the connection signal SGC to the indoor unit 50A. Furthermore, the determination unit 72 receives a connection signal SGC, which includes a unique address assigned to the alarm 57 corresponding to the indoor unit 50C, from the determination unit 72 of the indoor unit 50C. In other words, when the determination unit 72 of the indoor unit 50C receives a connection signal SGC, which includes a unique address assigned to the alarm 57, from the alarm 57 corresponding to the indoor unit 50C, it forwards the connection signal SGC to the indoor unit 50A.

[0100] Furthermore, the determination unit 72 receives a connection signal SGC, which includes a unique address assigned to the refrigerant sensor 56 corresponding to the indoor unit 50B, from the determination unit 72 of the indoor unit 50B. That is, when the determination unit 72 of the indoor unit 50B receives a connection signal SGC, which includes a unique address assigned to the refrigerant sensor 56, from the refrigerant sensor 56 corresponding to the indoor unit 50B, it forwards the connection signal SGC to the indoor unit 50A. Furthermore, the determination unit 72 receives a connection signal SGC, which includes a unique address assigned to the refrigerant sensor 56 corresponding to the indoor unit 50C, from the determination unit 72 of the indoor unit 50C. That is, when the determination unit 72 of the indoor unit 50C receives a connection signal SGC, which includes a unique address assigned to the refrigerant sensor 56, from the refrigerant sensor 56 corresponding to the indoor unit 50C, it forwards the connection signal SGC to the indoor unit 50A.

[0101] The execution unit 73, when the release reception unit 71 receives an instruction to release the interlock for the indoor unit 50, and the determination unit 72 determines that the safety devices 6 corresponding to each of the indoor units 50A, 50B, and 50C are properly connected, sets the execution unit 73 to an interlock release state that permits air conditioning operation for each of the indoor units 50A, 50B, and 50C. The execution unit 73 changes the release flag 77 stored in the indoor unit memory 75 of each of the indoor units 50A, 50B, and 50C from "0" (interlock state STL) to "1" (interlock release state STU) when the release reception unit 71 receives an instruction to release the interlock for the indoor unit 50, and the determination unit 72 determines that the safety devices 6 corresponding to each of the indoor units 50A, 50B, and 50C are properly connected. The release flag 77 indicates whether or not the interlock release state STU is in effect.

[0102] The execution unit 73 then transmits instruction information CM to the execution unit 73 of the indoor unit 50B to change the release flag 77 stored in the indoor unit memory 75 of the indoor unit 50B from "0" to "1". When the execution unit 73 of the indoor unit 50B receives the instruction information CM, it changes the release flag 77 stored in the indoor unit memory 75 of the indoor unit 50B from "0" to "1". Furthermore, the execution unit 73 transmits instruction information CM to the execution unit 73 of the indoor unit 50C to change the release flag 77 stored in the indoor unit memory 75 of the indoor unit 50C from "0" to "1". When the execution unit 73 of the indoor unit 50C receives the instruction information CM, it changes the release flag 77 stored in the indoor unit memory 75 of the indoor unit 50C from "0" to "1".

[0103] Furthermore, the execution unit 73 of each indoor unit 50A, indoor unit 50B, and indoor unit 50C changes the release flag 77 from "0" to "1" and then sends a release response signal to the outdoor unit 10. The release response signal indicates that the interlock release process has been completed in the indoor unit 50.

[0104] When the release flag 77 is "0", the execution unit 73 of each indoor unit 50A, indoor unit 50B, and indoor unit 50C enters an interlock state STL, which prohibits the air conditioning operation of each indoor unit 50A, indoor unit 50B, and indoor unit 50C. Furthermore, when the release flag 77 is set to "1", the execution unit 73 of each indoor unit 50A, indoor unit 50B, and indoor unit 50C enters an interlock release state STU, which allows air conditioning operation of each indoor unit 50A, indoor unit 50B, and indoor unit 50C.

[0105] When the release reception unit 71 receives an instruction to release the interlock for the indoor unit 50, and the determination unit 72 determines that the safety devices 6 corresponding to each of the indoor units 50A, 50B, and 50C are not properly connected, the execution unit 73 causes, for example, the remote control 90 corresponding to indoor unit 50A to notify error information in a manner that allows identification of the device among the components constituting the safety device 6 corresponding to each of the indoor units 50A, 50B, and 50C that is not properly connected.

[0106] The remote control 90 has, for example, an LCD (Liquid Crystal Display). The remote control 90 displays, in accordance with instructions from the execution unit 73, information indicating a group in which the safety device 6 is not properly connected, information indicating which of the indoor units 50 constituting the group has the safety device 6 not properly connected, and information indicating which of the devices constituting the safety device 6, namely the shut-off valve 8, refrigerant sensor 56, and alarm 57, is not properly connected.

[0107] In Embodiment 2, when the release reception unit 71 receives an instruction from the indoor unit 50 to release the interlock, and the determination unit 72 determines that the safety device 6 is not properly connected, the execution unit 73 causes the remote control 90 to notify error information in a manner that allows the identification of the device among the components of the safety device 6 that is not properly connected. However, the embodiments are not limited to this. For example, if the indoor unit control unit 60 is connected to a terminal device such as a personal computer or tablet device in a communicative manner, the execution unit 73 may cause the terminal device to notify error information in a manner that allows it to identify the group of safety devices 6 that are not properly connected, the safety devices 6 corresponding to each of the indoor units 50A, 50B, and 50C that are not properly connected, and the equipment constituting the safety device 6 that is not properly connected. The equipment constituting the safety device 6 is a shut-off valve 8, a refrigerant sensor 56, and an alarm 57.

[0108] Embodiment 2 describes the case where the refrigerant sensor 56 is located in each of the indoor units 50A, 50B, and 50C, but the refrigerant sensor 56 may also be located on the wall surface WS of the air-conditioned space. For example, one refrigerant sensor 56 may be located in one room. In this case, if the determination unit 72 determines that the refrigerant sensor 56 is not properly connected, it determines that the safety devices 6 corresponding to each of the indoor units 50A, 50B, and 50C are not properly connected.

[0109] Embodiment 2 describes the case in which the refrigerant sensor 56 is located in each of the indoor units 50A, 50B, and 50C. However, each of the indoor units 50A, 50B, and 50C may be equipped with a switching circuit that switches the refrigerant sensor 56 between an enabled state and an disabled state based on an operation from the worker W. In this case, the determination unit 72 determines that the safety device 6 is not properly connected if it determines that at least one of the switching circuits located in each of the indoor units 50A, 50B, and 50C is in an disabled state. The switching circuit consists of, for example, a switch that switches between the enabled and disabled states of the refrigerant sensor 56. The switch transmits a signal to the indoor unit control unit 60 of the indoor unit 50 indicating whether the refrigerant sensor 56 is enabled or disabled.

[0110] Embodiment 2 describes the case where the air conditioning system 1B is installed, but the indoor unit 50 may be renewed or an additional indoor unit 50 may be added. In this case, if at least one of the indoor units 50A, 50B, and 50C that constitute the first group GR1 is renewed, or if at least one additional indoor unit 50 is added to the indoor units 50A, 50B, and 50C that constitute the first group GR1, the determination unit 72 determines whether the safety device 6 is properly connected. In other words, when indoor units 50 other than indoor units 50A, 50B, and 50C that constitute the first group GR1 are renewed, and when indoor units 50 are added to groups other than the first group GR1, the determination unit 72 does not determine whether the safety device 6 is properly connected.

[0111] [2-2. Operation] [2-2-1. Interlock release process] Next, with reference to Figure 7, the procedure for releasing the interlock of the indoor unit 50, which is performed by the outdoor unit 10 and the indoor unit 50, will be described. Figure 7 is a flowchart showing the process for releasing the interlock of the indoor unit 50 in Embodiment 2. The outdoor unit 10 and the indoor unit 50 perform the processing shown in the flowchart in Figure 7 during initial communication after power-on, or when periodic communication is performed to exchange information between the outdoor unit 10 and the indoor unit 50.

[0112] Steps S301 to S307 in Figure 7 are processes performed by the outdoor unit control unit 20 of the outdoor unit 10, and steps S401 to S415 are processes performed by the indoor unit control unit 60 of the indoor unit 50. The indoor unit 50A, which is set as the master unit, executes the processes shown in steps S401 to S415 in Figure 7.

[0113] The outdoor unit control unit 20 of the outdoor unit 10 executes the processes from steps S301 to S303. First, in step S301, the transmitting unit 32 determines whether or not the power to the outdoor unit 10 has been turned on in a short-circuit state TS. In other words, the transmitting unit 32 determines whether or not the "predetermined conditions" are met.

[0114] If the transmitter 32 determines that the outdoor unit 10 is not powered on in a short-circuit state TS (step S301; NO), the process enters a standby state. If the transmitter 32 determines that the outdoor unit 10 is powered on in a short-circuit state TS (step S101; YES), the process proceeds to step S303. Then, in step S303, the transmitting unit 32 transmits an interlock release signal SGU to the indoor unit 50.

[0115] Next, the indoor unit control unit 60 of the indoor unit 50A, which is set as the master unit, executes the processes from steps S401 to S415. In step S401, the release reception unit 71 determines whether or not it has received the interlock release signal SGU transmitted from the outdoor unit 10. If the release reception unit 71 determines that it has not received the interlock release signal SGU transmitted from the outdoor unit 10 (step S401; NO), the process enters a standby state. If the release reception unit 71 determines that it has received the interlock release signal SGU transmitted from the outdoor unit 10 (step S401; YES), the process proceeds to step S403.

[0116] Then, in step S403, the determination unit 72 determines whether or not it has received connection signals SGC from all the shut-off valves 8 corresponding to each of the indoor units 50A, 50B, and 50C. The determination unit 72 receives the connection signals SGC from the shut-off valve 8 corresponding to indoor unit 50B via the indoor unit control unit 60 of indoor unit 50B. The determination unit 72 also receives the connection signals SGC from the shut-off valve 8 corresponding to indoor unit 50C via the indoor unit control unit 60 of indoor unit 50C.

[0117] If the determination unit 72 determines that it has not received a connection signal SGC from at least one of the shut-off valves 8 corresponding to each of the indoor units 50A, 50B, and 50C (step S403; NO), the process enters a standby state. If the determination unit 72 determines that it has received a connection signal SGC from all of the shut-off valves 8 corresponding to each of the indoor units 50A, 50B, and 50C (step S403; YES), the determination unit 72 determines that all of the shut-off valves 8 corresponding to each of the indoor units 50A, 50B, and 50C are properly connected, and the process proceeds to step S405.

[0118] Then, in step S405, the determination unit 72 determines whether or not it has received a connection signal SGC from the alarm 57 corresponding to each of the indoor units 50A, 50B, and 50C. The determination unit 72 receives the connection signal SGC from the alarm 57 corresponding to indoor unit 50B via the indoor unit control unit 60 of indoor unit 50B. The determination unit 72 also receives the connection signal SGC from the alarm 57 corresponding to indoor unit 50C via the indoor unit control unit 60 of indoor unit 50C.

[0119] If the determination unit 72 determines that it has not received a connection signal SGC from at least one of the alarm devices 57 corresponding to each of the indoor units 50A, 50B, and 50C (step S405; NO), the process proceeds to step S409. If the determination unit 72 determines that it has received a connection signal SGC from all of the alarm devices 57 corresponding to each of the indoor units 50A, 50B, and 50C (step S405; YES), the determination unit 72 determines that all of the alarm devices 57 corresponding to each of the indoor units 50A, 50B, and 50C are properly connected, and the process proceeds to step S407.

[0120] Then, in step S407, the determination unit 72 determines whether or not it has received a connection signal SGC from the refrigerant sensor 56 corresponding to each of the indoor units 50A, 50B, and 50C. The determination unit 72 receives the connection signal SGC from the refrigerant sensor 56 corresponding to indoor unit 50B via the indoor unit control unit 60 of indoor unit 50B. The determination unit 72 also receives the connection signal SGC from the refrigerant sensor 56 corresponding to indoor unit 50C via the indoor unit control unit 60 of indoor unit 50C.

[0121] If the determination unit 72 determines that it has received connection signals SGC from all refrigerant sensors 56 corresponding to each of the indoor units 50A, 50B, and 50C (step S407; YES), the determination unit 72 determines that the refrigerant sensors 56 are properly connected, and the process proceeds to step S413. If the determination unit 72 determines that it has not received connection signals SGC from at least one of the refrigerant sensors 56 corresponding to each of the indoor units 50A, 50B, and 50C (step S407; NO), the process proceeds to step S409.

[0122] If the answer is NO in step S405 and NO in step S407, then in step S409, the determination unit 72 determines whether a predetermined period PT has elapsed since the connection signal SGC was received from the shut-off valve 8. If the determination unit 72 determines that the predetermined period PT has not elapsed (step S409; NO), the process returns to step S405. If the determination unit 72 determines that the predetermined period PT has elapsed (step S409; YES), the process proceeds to step S411. Then, in step S411, the execution unit 73 causes the remote control 90 to notify error information in a manner that allows it to identify which of the devices constituting the safety device 6 is not properly connected. In this case, the indoor unit 50 maintains the interlock state. After that, the process ends.

[0123] If the answer in step S407 is YES, then in step S413, the execution unit 73 determines that all safety devices 6 corresponding to each of the indoor units 50A, 50B, and 50C are properly connected, and changes the release flag 77 from "0" (interlock state STL) to "1" (interlock release state STU). Furthermore, when the release flag 77 is changed to "1", the execution unit 73 sets the indoor unit 50A, 50B, and 50C to the interlock release state STU, which allows air conditioning operation for each of them. Next, in step S415, the execution unit 73 sends a release response signal to the outdoor unit 10. After that, the processing of the indoor unit control unit 60 of the indoor unit 50A is completed. The release response signal indicates that the interlock release process has been completed in each of the indoor units 50A, 50B, and 50C.

[0124] Next, the outdoor unit control unit 20 of the outdoor unit 10 executes the processes from steps S305 to S307. First, in step S305, the transmitting unit 32 determines whether or not it has received a release response signal from the indoor unit 50, which is set as the master unit for all groups. Furthermore, if an indoor unit 50 is added or replaced, "indoor unit 50 set as the master unit for all groups" in step S305 means the indoor unit 50 set as the master unit for all groups, including the added or replaced indoor unit 50. If the transmitter 32 determines that it has not received a release response signal from the indoor unit 50 configured as the master unit for all groups (step S305; NO), the process enters a standby state. If the transmitter 32 determines that it has received a release response signal from the indoor unit 50 configured as the master unit for all groups (step S305; YES), the process proceeds to step S307.

[0125] Then, in step S307, the transmitting unit 32 terminates the transmission of the interlock release signal SGU to the indoor unit 50. After that, the processing of the outdoor unit control unit 20 of the outdoor unit 10 is terminated.

[0126] Steps S301 to S303 correspond to an example of the "transmission step". Steps S401 to S407 correspond to an example of a "decision step". Step S413 corresponds to an example of an "execution step".

[0127] [2-3. Effects, etc.] As described above, the air conditioning system 1B is an air conditioning system 1 having an outdoor unit 10 and an indoor unit 50 that are connected to each other in a manner that enables communication between them. The outdoor unit 10 transmits an interlock release signal SGU to the indoor unit 50 when predetermined conditions are met. The indoor unit 50 includes a determination unit 72 that determines whether a safety device 6, which functions as a measure against refrigerant leakage, is properly connected when it receives the interlock release signal SGU from the outdoor unit 10. The indoor unit 50 includes an execution unit 73 that sets the indoor unit 50 to an interlock release state STU, which allows air conditioning operation, if the determination unit 72 determines that the safety device 6 is properly connected, and sets the indoor unit 50 to an interlock state STL, which prohibits air conditioning operation, if the determination unit 72 determines that the safety device 6 is not properly connected.

[0128] According to the above configuration, when an interlock release signal SGU is received from the outdoor unit 10, if the safety device 6 is properly connected, the system will be in an interlock release state STU, which allows air conditioning operation of the indoor unit 50, and in an interlock state STL, which prohibits air conditioning operation of the indoor unit 50, if the safety device 6 is not properly connected. Therefore, the burden on the worker W to release the interlock is reduced, and the interlock release can be performed properly.

[0129] In the above-described air conditioning system 1B, the safety device 6 includes a shut-off valve 8 that blocks the flow of refrigerant, a refrigerant sensor 56 that detects refrigerant leakage, and an alarm 57 that outputs an alarm. The determination unit 72 determines whether the refrigerant sensor 56 and the alarm 57 are properly connected when the shut-off valve 8 is properly connected, and determines that the safety device 6 is not properly connected if it determines that at least one of the refrigerant sensor 56 and the alarm 57 is not properly connected.

[0130] According to this, the safety device 6 includes a shut-off valve 8, a refrigerant sensor 56, and an alarm 57. When the shut-off valve 8 is properly connected, it is determined whether the refrigerant sensor 56 and the alarm 57 are properly connected. If at least one of the refrigerant sensor 56 and the alarm 57 is not properly connected, it is determined that the safety device 6 is not properly connected. Therefore, it is possible to properly determine whether the safety device 6 is properly connected. Consequently, safety can be improved by suppressing air conditioning operation due to incorrect interlock release by the worker W.

[0131] In the above-described air conditioning system 1B, if the shut-off valve 8, refrigerant sensor 56, and alarm 57 are properly connected to the indoor unit 50, each of the shut-off valve 8, refrigerant sensor 56, and alarm 57 transmits a connection signal SGC to the indoor unit 50 indicating that they are properly connected. The determination unit 72 determines that the safety device 6 is not properly connected if it does not receive a connection signal SGC from at least one of the refrigerant sensor 56 and alarm 57 within a predetermined period PT from the time it receives the connection signal SGC from the shut-off valve 8.

[0132] According to this, if the connection signal SGC is not received from at least one of the refrigerant sensor 56 and the alarm 57 within a predetermined period PT from the time the connection signal SGC is received from the shut-off valve 8, it is determined that the safety device 6 is not properly connected. Therefore, by setting the predetermined period PT to an appropriate period, the burden on the worker W to release the interlock is reduced, and the interlock can be released properly.

[0133] In the above-mentioned air conditioning system 1B, the determination unit 72 determines that the safety device 6 is not properly connected if the alarm 57 is properly connected but the refrigerant sensor 56 is not properly connected.

[0134] According to this, if the alarm 57 is properly connected but the refrigerant sensor 56 is not properly connected, it is determined that the safety device 6 is not properly connected, thus allowing for a proper determination of whether the safety device 6 is properly connected or not. Therefore, safety can be improved by suppressing air conditioning operation caused by incorrect interlock release by the worker W.

[0135] In the above-described air conditioning system 1B, the air conditioning system 1 includes a first group GR1 consisting of a plurality of indoor units 50 that conditioned the air in a single target space, and when the refrigerant sensor 56 is located on the wall surface WS that forms the single target space, the determination unit 72 determines that the safety device 6 is not properly connected if it determines that the refrigerant sensor 56 is not properly connected, and when the refrigerant sensor 56 is located inside each of the plurality of indoor units 50, the determination unit 72 determines that the safety device 6 is not properly connected if it determines that at least one of the refrigerant sensors 56 located in each of the plurality of indoor units 50 is not properly connected.

[0136] According to this, whether the refrigerant sensor 56 is located on a wall surface WS forming a single target space, or whether the refrigerant sensor 56 is located inside each of the multiple indoor units 50, it is possible to properly determine whether the safety device 6 is properly connected. Therefore, safety can be improved by suppressing air conditioning operation caused by incorrect interlock release by the worker W.

[0137] In the above-described air conditioning system 1B, when the refrigerant sensor 56 is located inside each of the multiple indoor units 50, each of the multiple indoor units 50 is equipped with a switching circuit that switches between an enabled state and an disabled state of the refrigerant sensor 56, and the determination unit 72 determines that the safety device 6 is not properly connected when it determines that at least one of the switching circuits located in each of the multiple indoor units 50 is in an disabled state.

[0138] According to this, when a switching circuit is provided to switch between the enabled and disabled states of the refrigerant sensor 56, it is possible to properly determine whether the safety device 6 is properly connected or not. Therefore, the burden on the operator W to release the interlock is reduced, and the interlock can be released properly.

[0139] In the above-described air conditioning system 1B, when an indoor unit 50 is renewed or an additional indoor unit 50 is added, the determination unit 72 determines whether the safety device 6 is properly connected when at least one of the multiple indoor units 50 is renewed, or when at least one additional indoor unit 50 is added to the multiple indoor units 50.

[0140] According to this, when the indoor unit 50 is renewed or additional indoor units 50 are installed, it is possible to properly determine whether the safety device 6 is properly connected. Therefore, the burden on the worker W to release the interlock is reduced, and the interlock can be released properly.

[0141] In the above-described air conditioning system 1B, the air conditioning system 1B includes a first group GR1 and a second group GR2 which consists of multiple indoor units 50 different from the multiple indoor units 50 that make up the first group GR1. When the determination unit 72 determines that the safety device 6 is not properly connected, the execution unit 73 notifies error information in a manner that allows identification of the group corresponding to the safety device 6 and the equipment among the equipment that makes up the safety device 6 that is not properly connected.

[0142] According to this, if a worker determines that a safety device 6 is not properly connected, they can identify the group corresponding to the safety device 6 that was determined to be improperly connected, and the equipment that is not properly connected among the components of the safety device 6 that was determined to be improperly connected. Therefore, the convenience of the worker W can be improved.

[0143] The control method for the air conditioning system 1B includes an outdoor unit 10 and an indoor unit 50 that are connected to each other in a manner that enables communication, and includes: a transmission step in which the outdoor unit 10 transmits an interlock release signal SGU to the indoor unit 50 when predetermined conditions are met; a determination step in which the indoor unit 50, upon receiving the interlock release signal SGU from the outdoor unit 10, determines whether a safety device 6 that functions as a measure against refrigerant leakage is properly connected; and an execution step in which, if the determination step determines that the safety device 6 is properly connected, the indoor unit 50 is set to an interlock release state STU that permits air conditioning operation, and if the determination step determines that the safety device 6 is not properly connected, the indoor unit 50 is set to an interlock state STL that prohibits air conditioning operation.

[0144] According to this, the control method for the air conditioning system 1B produces the same effect as the air conditioning system 1B described above.

[0145] [3. Effects, etc.] As described above, the air conditioning system 1 (i.e., the air conditioning system 1A of Embodiment 1 and the air conditioning system 1B of Embodiment 2) is an air conditioning system 1 having an outdoor unit 10 and an indoor unit 50 that are connected to each other in a manner that allows them to communicate with each other. The outdoor unit 10 transmits an interlock release signal SGU to the indoor unit 50 when predetermined conditions are met. The indoor unit 50 includes a determination unit 72 that determines whether a safety device 6, which functions as a measure against refrigerant leakage, is properly connected when it receives the interlock release signal SGU from the outdoor unit 10. The indoor unit 50 includes an execution unit 73 that sets the indoor unit 50 to an interlock release state STU, which allows air conditioning operation, when the determination unit 72 determines that the safety device 6 is properly connected, and sets the indoor unit 50 to an interlock state STL, which prohibits air conditioning operation, when the determination unit 72 determines that the safety device 6 is not properly connected.

[0146] According to the above configuration, when an interlock release signal SGU is received from the outdoor unit 10, if the safety device 6 is properly connected, the system will be in an interlock release state STU, which allows air conditioning operation of the indoor unit 50, and in an interlock state STL, which prohibits air conditioning operation of the indoor unit 50, if the safety device 6 is not properly connected. Therefore, the burden on the worker W to release the interlock is reduced, and the interlock release can be performed properly.

[0147] In the above-described air conditioning system 1, the safety device 6 includes a shut-off valve 8 that blocks the flow of refrigerant, a refrigerant sensor 56 that detects refrigerant leakage, and an alarm 57 that outputs an alarm. The determination unit 72 determines whether the refrigerant sensor 56 and the alarm 57 are properly connected when the shut-off valve 8 is properly connected, and determines that the safety device 6 is not properly connected if it determines that at least one of the refrigerant sensor 56 and the alarm 57 is not properly connected.

[0148] According to this, the safety device 6 includes a shut-off valve 8, a refrigerant sensor 56, and an alarm 57. When the shut-off valve 8 is properly connected, it is determined whether the refrigerant sensor 56 and the alarm 57 are properly connected. If at least one of the refrigerant sensor 56 and the alarm 57 is not properly connected, it is determined that the safety device 6 is not properly connected. Therefore, it is possible to properly determine whether the safety device 6 is properly connected. Consequently, safety can be improved by suppressing air conditioning operation due to incorrect interlock release by the worker W.

[0149] In the above-described air conditioning system 1, if the shut-off valve 8, refrigerant sensor 56, and alarm 57 are properly connected to the indoor unit 50, each of the shut-off valve 8, refrigerant sensor 56, and alarm 57 transmits a connection signal SGC to the indoor unit 50 indicating that they are properly connected. The determination unit 72 determines that the safety device 6 is not properly connected if it does not receive a connection signal SGC from at least one of the refrigerant sensor 56 and alarm 57 within a predetermined period PT from the time it receives the connection signal SGC from the shut-off valve 8.

[0150] According to this, if the connection signal SGC is not received from at least one of the refrigerant sensor 56 and the alarm 57 within a predetermined period PT from the time the connection signal SGC is received from the shut-off valve 8, it is determined that the safety device 6 is not properly connected. Therefore, by setting the predetermined period PT to an appropriate period, the burden on the worker W to release the interlock is reduced, and the interlock can be released properly.

[0151] In the above-described air conditioning system 1, the determination unit 72 determines that the safety device 6 is not properly connected if the alarm 57 is properly connected but the refrigerant sensor 56 is not properly connected.

[0152] According to this, if the alarm 57 is properly connected but the refrigerant sensor 56 is not properly connected, it is determined that the safety device 6 is not properly connected, thus allowing for a proper determination of whether the safety device 6 is properly connected or not. Therefore, safety can be improved by suppressing air conditioning operation caused by incorrect interlock release by the worker W.

[0153] In the above-described air conditioning system 1, the air conditioning system 1 includes a first group GR1 consisting of a plurality of indoor units 50 that conditioned the air in a single target space, and when the refrigerant sensor 56 is located on the wall surface WS that forms the single target space, the determination unit 72 determines that the safety device 6 is not properly connected if it determines that the refrigerant sensor 56 is not properly connected, and when the refrigerant sensor 56 is located inside each of the plurality of indoor units 50, the determination unit 72 determines that the safety device 6 is not properly connected if it determines that at least one of the refrigerant sensors 56 located in each of the plurality of indoor units 50 is not properly connected.

[0154] According to this, whether the refrigerant sensor 56 is located on a wall surface WS forming a single target space, or whether the refrigerant sensor 56 is located inside each of the multiple indoor units 50, it is possible to properly determine whether the safety device 6 is properly connected. Therefore, safety can be improved by suppressing air conditioning operation caused by incorrect interlock release by the worker W.

[0155] In the above-described air conditioning system 1, when the refrigerant sensor 56 is located inside each of the multiple indoor units 50, each of the multiple indoor units 50 is equipped with a switching circuit that switches between an enabled state and an disabled state of the refrigerant sensor 56, and the determination unit 72 determines that the safety device 6 is not properly connected when it determines that at least one of the switching circuits located in each of the multiple indoor units 50 is in an disabled state.

[0156] According to this, when a switching circuit is provided to switch between the enabled and disabled states of the refrigerant sensor 56, it is possible to properly determine whether the safety device 6 is properly connected or not. Therefore, the burden on the operator W to release the interlock is reduced, and the interlock can be released properly.

[0157] In the above-described air conditioning system 1, when an indoor unit 50 is renewed or an additional indoor unit 50 is added, the determination unit 72 determines whether the safety device 6 is properly connected when at least one of the multiple indoor units 50 is renewed, or when at least one indoor unit 50 is added to the multiple indoor units 50.

[0158] According to this, when the indoor unit 50 is renewed or additional indoor units 50 are installed, it is possible to properly determine whether the safety device 6 is properly connected. Therefore, the burden on the worker W to release the interlock is reduced, and the interlock can be released properly.

[0159] In the above-described air conditioning system 1, the air conditioning system 1 includes a first group GR1 and a second group GR2 which consists of multiple indoor units 50 different from the multiple indoor units 50 that make up the first group GR1. When the determination unit 72 determines that the safety device 6 is not properly connected, the execution unit 73 notifies error information in a manner that allows identification of the group corresponding to the safety device 6 and the equipment among the equipment that makes up the safety device 6 that is not properly connected.

[0160] According to this, if a worker determines that a safety device 6 is not properly connected, they can identify the group corresponding to the safety device 6 that was determined to be improperly connected, and the equipment that is not properly connected among the components of the safety device 6 that was determined to be improperly connected. Therefore, the convenience of the worker W can be improved.

[0161] The control method for the air conditioning system 1 includes an outdoor unit 10 and an indoor unit 50 that are connected to each other in a manner that enables communication, and includes: a transmission step in which the outdoor unit 10 transmits an interlock release signal SGU to the indoor unit 50 when predetermined conditions are met; a determination step in which the indoor unit 50, upon receiving the interlock release signal SGU from the outdoor unit 10, determines whether a safety device 6 that functions as a measure against refrigerant leakage is properly connected; and an execution step in which, if the determination step determines that the safety device 6 is properly connected, the indoor unit 50 is set to an interlock release state STU that permits air conditioning operation, and if the determination step determines that the safety device 6 is not properly connected, the indoor unit 50 is set to an interlock state STL that prohibits air conditioning operation.

[0162] According to this, the control method for the air conditioning system 1 produces the same effects as the air conditioning system 1 described above.

[0163] (Other embodiments) As described above, the above embodiments have been explained as examples of the technology disclosed in this application. However, the technology in this disclosure is not limited to these embodiments and can be applied to embodiments that have been modified, replaced, added, or omitted. Therefore, other embodiments will be described below as examples.

[0164] In the above embodiment, the case in which the air conditioning system 1 is equipped with three indoor units 50 (indoor unit 50A, indoor unit 50B, and indoor unit 50C) has been mainly described, but there may be one indoor unit 50, two indoor units, or four or more indoor units 50.

[0165] In the above embodiment, the case in which the refrigerant sensor 56 is located inside the indoor unit 50 was described, but the refrigerant sensor 56 may also be located separately from the indoor unit 50.

[0166] In the above embodiment, the execution unit 73 causes the remote control 90 to notify error information in a manner that allows it to identify which of the devices constituting the safety device 6 is not properly connected, but the embodiment is not limited thereto. For example, the execution unit 73 may cause terminal devices such as personal computers and tablet devices to notify error information in a manner that allows it to identify which of the safety devices 6 corresponding to indoor units 50A, 50B, and 50C are not properly connected, and which of the devices constituting the safety device 6 are not properly connected. Furthermore, if the air conditioning system 1 comprises a plurality of indoor units 50 constituting a first group GR1 and a plurality of indoor units 50 constituting a second group GR2, the execution unit 73 may, for example, cause a terminal device such as a personal computer or tablet device to notify error information in a manner that allows for the identification of the group corresponding to the improperly connected safety device 6, the improperly connected safety device 6 among the safety devices 6 corresponding to each of the plurality of indoor units 50, and the improperly connected equipment among the equipment constituting the safety device 6.

[0167] The outdoor unit processor 30 and the indoor unit processor 70 may each consist of a single processor or multiple processors. These processors may also be hardware programmed to implement the corresponding functional units. That is, these processors may consist of, for example, an ASIC (Application Specific Integrated Circuit) or an FPGA (Field Programmable Gate Array).

[0168] The outdoor unit communication circuit 21 and the indoor unit communication circuit 61 may each perform wireless communication. For wireless connection, standards such as Wi-Fi (registered trademark) and WiMAX (registered trademark) may be used.

[0169] In the flowcharts shown in Figures 4 and 7, the processing steps of the outdoor unit control unit 20 and the indoor unit control unit 60 are divided according to their main processing content to facilitate understanding of their operation. The operation is not limited by the way the processing units are divided or the names of those divisions. Depending on the processing content, the units may be further divided into more steps. Alternatively, each step unit may be divided to include even more processing. Furthermore, the order of the steps may be rearranged as appropriate, as long as it does not impede the intent of this disclosure.

[0170] Since the embodiments described above are for illustrative purposes of the technology described herein, various modifications, substitutions, additions, omissions, etc., can be made within the scope of the claims or equivalents thereof.

[0171] (Note) Based on the above description of embodiments, the following technologies are disclosed.

[0172] (Technology 1) An air conditioning system having an outdoor unit and an indoor unit that are connected to each other in a manner that allows them to communicate with each other, wherein the outdoor unit transmits an interlock release signal to the indoor unit when predetermined conditions are met, and the indoor unit comprises a determination unit that determines whether a safety device that functions as a measure against refrigerant leakage is properly connected when it receives the interlock release signal from the outdoor unit, and an execution unit that sets the indoor unit to an interlock state that permits air conditioning operation of the indoor unit when the determination unit determines that the safety device is properly connected, and sets the indoor unit to an interlock state that prohibits air conditioning operation of the indoor unit when the determination unit determines that the safety device is not properly connected.

[0173] With this configuration, when an interlock release signal is received from the outdoor unit, the system will enter an interlock release state that allows air conditioning operation of the indoor unit if the safety device is properly connected, and an interlock state that prohibits air conditioning operation of the indoor unit if the safety device is not properly connected. Therefore, the burden on operators to release the interlock is reduced, and the interlock release can be performed properly.

[0174] (Technology 2) The air conditioning system according to Technical 1, wherein the safety device includes a shut-off valve for blocking the flow of refrigerant, a refrigerant sensor for detecting refrigerant leakage, and an alarm for outputting an alarm, and the determination unit determines whether the refrigerant sensor and the alarm are properly connected when the shut-off valve is properly connected, and determines that the safety device is not properly connected when it is determined that at least one of the refrigerant sensor and the alarm is not properly connected.

[0175] In this configuration, the safety device includes a shut-off valve, a refrigerant sensor, and an alarm. When the shut-off valve is properly connected, it is determined whether the refrigerant sensor and the alarm are properly connected. If at least one of the refrigerant sensor and the alarm is not properly connected, it is determined that the safety device is not properly connected. Therefore, it is possible to properly determine whether the safety device is properly connected. Consequently, safety can be improved by suppressing air conditioning operation caused by incorrect interlock release by the operator.

[0176] (Technology 3) The air conditioning system according to Technical 2, wherein when each of the shut-off valve, the refrigerant sensor, and the alarm is properly connected to the indoor unit, each of the shut-off valve, the refrigerant sensor, and the alarm transmits a connection signal to the indoor unit indicating that it is properly connected, and the determination unit determines that the safety device is not properly connected if it does not receive the connection signal from at least one of the refrigerant sensor and the alarm within a predetermined period of time from when it receives the connection signal from the shut-off valve.

[0177] In this configuration, if a connection signal is not received from at least one of the refrigerant sensor and the alarm within a predetermined period after receiving a connection signal from the shut-off valve, it is determined that the safety device is not properly connected. Therefore, by setting the predetermined period to an appropriate length, the burden on the operator to release the interlock is reduced, and the interlock can be released properly.

[0178] (Technology 4) The air conditioning system according to Technology 3, wherein the determination unit determines that the safety device is not properly connected when the alarm is properly connected and the refrigerant sensor is not properly connected.

[0179] With this configuration, if the alarm is properly connected but the refrigerant sensor is not properly connected, it is determined that the safety device is not properly connected, thus allowing for a proper determination of whether the safety device is properly connected or not. Therefore, safety can be improved by suppressing air conditioning operation caused by incorrect interlock release by the operator.

[0180] (Technology 5) The air conditioning system according to any one of the technologies 2 to 4, wherein the air conditioning system includes a first group consisting of a plurality of indoor units that conditioned the air in a single target space, and when the refrigerant sensor is located on a wall surface forming the single target space, the determination unit determines that the safety device is not properly connected if it determines that the refrigerant sensor is not properly connected, and when the refrigerant sensor is located inside each of the plurality of indoor units, the determination unit determines that the safety device is not properly connected if it determines that at least one of the refrigerant sensors located in each of the plurality of indoor units is not properly connected.

[0181] This configuration allows for accurate determination of whether the safety device is properly connected, whether the refrigerant sensor is located on a wall forming a single target space or inside each of multiple indoor units. Therefore, safety can be improved by suppressing air conditioning operation caused by incorrect interlock release by operators.

[0182] (Technology 6) The air conditioning system according to Technical Reference 5, wherein the refrigerant sensor is located inside each of the multiple indoor units, each of the multiple indoor units is equipped with a switching circuit for switching between an enabled state and an disabled state of the refrigerant sensor, and the determination unit determines that the safety device is not properly connected when it determines that at least one of the switching circuits located in each of the multiple indoor units is in the disabled state.

[0183] This configuration allows for proper determination of whether the safety device is properly connected, even when a switching circuit is provided to switch between the enabled and disabled states of the refrigerant sensor. Therefore, it reduces the burden on the operator in releasing the interlock and ensures that the interlock is released correctly.

[0184] (Technology 7) The air conditioning system according to Technology 5 or Technology 6, wherein when an indoor unit is renewed or an indoor unit is added, the determination unit determines whether the safety device is properly connected when at least one of the multiple indoor units is renewed or when at least one indoor unit is added to the multiple indoor units.

[0185] This configuration allows for proper determination of whether the safety device is properly connected when an indoor unit is refurbished or an additional indoor unit is installed. Therefore, it reduces the burden on workers in disengaging the interlock and ensures that the interlock is properly disengaged.

[0186] (Technology 8) The air conditioning system includes a first group and a second group consisting of multiple indoor units different from the multiple indoor units that make up the first group, and when the determination unit determines that the safety device is not properly connected, the execution unit notifies error information in a manner that allows identification of the group corresponding to the safety device and the equipment among the equipment that makes up the safety device that is not properly connected, as described in any one of technologies 5 to 7.

[0187] With this configuration, if a worker determines that a safety device is not properly connected, they can identify the group of safety devices that are determined to be improperly connected, and the specific components of the safety device that are not properly connected. Therefore, worker convenience can be improved.

[0188] (Technology 9) A control method for an air conditioning system having an outdoor unit and an indoor unit that are connected to each other in a manner that allows them to communicate with each other, the method comprising: a transmission step in which the outdoor unit transmits an interlock release signal to the indoor unit when predetermined conditions are met; a determination step in which the indoor unit, upon receiving the interlock release signal from the outdoor unit, determines whether a safety device that functions as a measure against refrigerant leakage is properly connected; and an execution step in which, if the determination step determines that the safety device is properly connected, the indoor unit is set to an interlock release state that permits air conditioning operation, and if the determination step determines that the safety device is not properly connected, the indoor unit is set to an interlock state that prohibits air conditioning operation.

[0189] This configuration produces the same effect as the air conditioning system of Technology 1. [Industrial applicability]

[0190] This disclosure is applicable to applications that reduce the burden on workers in releasing interlocks and ensure proper interlock release. [Explanation of Symbols]

[0191] 1A, 1B, 1 Air conditioning unit 10 Outdoor unit 20 Outdoor unit control unit 21 Indoor unit communication circuit 30 Outdoor Unit Processor 31 State detection unit 32 Transmitter 35 Outdoor unit memory 36 Outdoor Unit Program 50A, 50B, 50C, 50 indoor unit 60 Indoor Unit Control Unit 61 Indoor unit communication circuit 70 Indoor Unit Processor 71 Cancellation Request Department 72 Judgment section 73 Execution Department 75 Indoor unit memory 76 Indoor Unit Program 77 Release Flag (Interlock Release Information) 6 Safety equipment 56 Refrigerant sensor (part of the safety device) 57. Alarm devices (part of safety devices) 8. Shut-off valve (part of the safety device) 80 First shut-off valve 81 Second shut-off valve 90 Remote Control GR1 Group 1 GR2 Group 2 PT predetermined period SGU Interlock Release Signal SGC connection signal STL Interlock Status STU Interlock Released State W Worker

Claims

1. An air conditioning system having an outdoor unit and an indoor unit that are connected to each other in a manner that enables communication between them, The outdoor unit transmits an interlock release signal to the indoor unit when predetermined conditions are met. The aforementioned indoor unit is A determination unit that, upon receiving the interlock release signal from the outdoor unit, determines whether a safety device that functions as a refrigerant leak prevention measure is properly connected, An execution unit that, when the determination unit determines that the safety device is properly connected, sets the interlock to a release state that permits the indoor unit's air conditioning operation, and when the determination unit determines that the safety device is not properly connected, sets the interlock to a state that prohibits the indoor unit's air conditioning operation. An air conditioning system equipped with the following features.

2. The safety device includes a shut-off valve for blocking the flow of refrigerant, a refrigerant sensor for detecting refrigerant leakage, and an alarm device for outputting an alarm. The determination unit, When the shut-off valve is properly connected, it is determined whether the refrigerant sensor and the alarm are properly connected. If it is determined that at least one of the refrigerant sensor and the alarm is not properly connected, it is determined that the safety device is not properly connected. The air conditioning device according to claim 1.

3. When the shut-off valve, the refrigerant sensor, and the alarm are properly connected to the indoor unit, each of the shut-off valve, the refrigerant sensor, and the alarm transmits a connection signal to the indoor unit indicating that they are properly connected. The determination unit determines that the safety device is not properly connected if it does not receive the connection signal from at least one of the refrigerant sensor and the alarm device within a predetermined period of time from the time it receives the connection signal from the shut-off valve. The air conditioning device according to claim 2.

4. The determination unit determines that the safety device is not properly connected if the refrigerant sensor is not properly connected when the alarm is properly connected. The air conditioning device according to claim 2.

5. The aforementioned air conditioning system includes a first group consisting of multiple indoor units that conditioned the air in a single target space. When the refrigerant sensor is positioned on a wall surface forming the one target space, If the determination unit determines that the refrigerant sensor is not properly connected, it determines that the safety device is not properly connected. If the refrigerant sensor is located inside each of the multiple indoor units, The determination unit determines that the safety device is not properly connected if it determines that at least one of the refrigerant sensors located in each of the multiple indoor units is not properly connected. An air conditioning device according to any one of claims 2 to 4.

6. When the refrigerant sensor is located inside each of the multiple indoor units, Each of the aforementioned multiple indoor units is equipped with a switching circuit for switching between the enabled and disabled states of the refrigerant sensor. The determination unit determines that the safety device is not properly connected when it determines that at least one of the switching circuits located in each of the multiple indoor units is in the disabled state. The air conditioning device according to claim 5.

7. When an indoor unit is refurbished or an additional indoor unit is installed, When at least one of the aforementioned multiple indoor units is replaced, or when at least one additional indoor unit is added to the aforementioned multiple indoor units, the determination unit determines whether the safety device is properly connected. The air conditioning device according to claim 5.

8. The air conditioning system includes the first group and the second group, which consists of a plurality of indoor units different from the plurality of indoor units that make up the first group. If the determination unit determines that the safety device is not properly connected, The execution unit notifies error information in a manner that allows for the identification of the group corresponding to the safety device and the equipment among the components of the safety device that is not properly connected. The air conditioning device according to claim 5.

9. A control method for an air conditioning system having an outdoor unit and an indoor unit that are connected to each other in a manner that enables communication between them, A transmission step in which the outdoor unit sends an interlock release signal to the indoor unit when predetermined conditions are met, The aforementioned indoor unit, A determination step in which, upon receiving the interlock release signal from the outdoor unit, a determination is made to determine whether the safety device that functions as a refrigerant leak prevention measure is properly connected, If the determination step determines that the safety device is properly connected, the execution step sets the indoor unit to an interlock release state that permits air conditioning operation, and if the determination step determines that the safety device is not properly connected, the execution step sets the indoor unit to an interlock state that prohibits air conditioning operation. A method for controlling an air conditioning system, including the control of an air conditioning system.

Images