Air conditioning system and control method for air conditioning system

Abstract

This disclosure provides an air conditioning system that can reduce the burden on workers during installation when the indoor unit can use a first refrigerant and a second refrigerant which is more flammable than the first refrigerant. [Solution] The outdoor unit includes a switching circuit that switches between a first state and a second state different from the first state based on user operation, and a transmitting unit that transmits an interlock release signal to the indoor unit when the switching circuit is in the second state. The indoor unit includes an execution unit that, when the refrigerant of the air conditioner is a first refrigerant, sets the indoor unit to an interlock release state that permits air conditioning operation, and when the refrigerant of the air conditioner is a second refrigerant, sets the indoor unit to an interlock state that prohibits air conditioning operation when an interlock release signal has not been received from the outdoor unit.

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 the availability of air conditioning operation 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 can reduce the burden on an operator during installation work when an indoor unit can use a first refrigerant and a second refrigerant that is more flammable than the first refrigerant.

Means for Solving the Problems

[0005] The air conditioning system in this disclosure comprises an outdoor unit and an indoor unit connected to the outdoor unit by refrigerant piping, which can use a first refrigerant and a second refrigerant that is more flammable than the first refrigerant, wherein the outdoor unit includes a switching circuit that switches between a first state and a second state different from the first state based on user operation, and a transmitting unit that transmits an interlock release signal to the indoor unit when the switching circuit is in the second state, and the indoor unit includes an execution unit that sets the indoor unit to an interlock release state that permits air conditioning operation when the refrigerant of the air conditioning system is the first refrigerant, and sets the indoor unit to an interlock state that prohibits air conditioning operation when the refrigerant of the air conditioning system is the second refrigerant and has not received an interlock release signal from the outdoor unit.

[0006] The control method for an air conditioning system in this disclosure comprises an outdoor unit and an indoor unit connected to the outdoor unit by refrigerant piping, which can use a first refrigerant and a second refrigerant that is more flammable than the first refrigerant, wherein the outdoor unit performs a switching step of switching between a first state and a second state different from the first state based on user operation, and a transmission step of transmitting an interlock release signal to the indoor unit if the outdoor unit is in the second state in the switching step, and the indoor unit performs an execution step of setting up an interlock release state that permits air conditioning operation of the indoor unit if the refrigerant of the air conditioning system is the first refrigerant, and setting up an interlock state that prohibits air conditioning operation of the indoor unit if the refrigerant of the air conditioning system is the second refrigerant and the indoor unit has not received an interlock release signal from the outdoor unit. [Effects of the Invention]

[0007] The air conditioning system and control method for the air conditioning system described herein can reduce the burden on workers. [Brief explanation of the drawing]

[0008] [Figure 1] Diagram showing the overall configuration of the air conditioning system in the embodiment. [Figure 2] This diagram shows the configuration of the control unit between the outdoor unit and the indoor unit in the embodiment. [Figure 3] Diagram showing the arrangement of the connection part of the high-voltage switch in the embodiment. [Figure 4] Flowchart showing the process of releasing the interlock of the indoor unit in the embodiment [Figure 5] A diagram showing the procedure for installing the air conditioning system in the embodiment. [Figure 6] A diagram showing a modified configuration in which the outdoor unit is equipped with a dedicated part for unlocking the indoor unit's interlock. [Figure 7] A diagram showing a modified form of an air conditioning system that includes a master outdoor unit and a slave outdoor unit. [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.

[0011] However, when an indoor unit can use both a first refrigerant and a second refrigerant that is more flammable than the first refrigerant, it is necessary to perform an interlock release operation even on indoor units that do not require safety measures, which could potentially increase the burden on workers during installation. For example, if an indoor unit uses "R410A" as the first refrigerant and "R32" as the second refrigerant, safety measures during installation are not required when using the first refrigerant, "R410A." On the other hand, safety measures during installation are required when using the second refrigerant, "R32." In other words, the inventors discovered a problem in reducing the burden on workers when an indoor unit can use a first refrigerant and a second refrigerant which is more flammable than the first refrigerant, and the subject matter of this disclosure was established in order to solve this problem. Therefore, this disclosure provides an air conditioning system and a control method for the air conditioning system that can reduce the burden on operators when the indoor unit can use a first refrigerant and a second refrigerant which is more flammable than the first refrigerant.

[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] (Embodiment 1) This embodiment will be described below with reference to Figures 1 to 5. [1-1. Structure] [1-1-1. Configuration of the air conditioning system] First, the overall configuration of the air conditioning system 1 in this embodiment will be described with reference to Figure 1. Figure 1 is a diagram showing the overall configuration of the air conditioning system 1 in this embodiment. As shown in Figure 1, the air conditioning system 1 comprises 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 piping 2. Note that there may be one indoor unit 50, two indoor units, or four or more indoor units 50.

[0014] In the air conditioning system 1, the outdoor unit 10, the indoor unit 50, and the refrigerant piping 2 constitute a refrigeration cycle 5. The air conditioning system 1 circulates the refrigerant compressed by the outdoor unit 10 between the outdoor unit 10 and the indoor unit 50 via the refrigerant piping 2, thereby providing air conditioning to the room in which the indoor unit 50 is installed. In this embodiment, the case where the air conditioner 1 uses a non-flammable refrigerant "R410A" and a flammable refrigerant "R32" as refrigerants will be described. "R410A" corresponds to an example of the "first refrigerant". "R32" corresponds to an example of the "second refrigerant".

[0015] In this embodiment, the case where the "first refrigerant" is "R410A" and the "second refrigerant" is "R32" will be described, but the embodiment is not limited thereto. It is only necessary that the "second refrigerant" is a more flammable refrigerant than the "first refrigerant". For example, the "first refrigerant" may be "R'32" and the "second refrigerant" may be "R290".

[0016] Note that it is preferable that the "first refrigerant" is a non-flammable refrigerant. For example, the "first refrigerant" may be "R134a" and the "second refrigerant" may be "R32". The "second refrigerant" is, for example, a flammable refrigerant. The flammable refrigerant may be a mixed refrigerant containing 70% by weight or more of "R32", propane, or a mixed refrigerant containing propane.

[0017] Before the start of use, the indoor unit 50 is in an interlock state in which air conditioning operation is prohibited. When using the flammable refrigerant "R32", the installer W of the air conditioner 1 needs to confirm that the indoor unit 50 is properly installed and release the interlock of the indoor unit 50. <% The air conditioner 1 of the present disclosure is configured to be able to release the interlocks of each indoor unit 50 collectively by operating the outdoor unit 10 in order to facilitate the work of releasing the interlock of the indoor unit 50 by the installer W. Details of such a configuration will be described later. The installer W corresponds to an example of the "user".

[0018] When using the non-flammable refrigerant "R410A", the worker W installing the air conditioning system 1 may release the interlock of the indoor unit 50 without having to perform the task of confirming that the indoor unit 50 is properly installed. The air conditioning system 1 of this disclosure includes a configuration in which the outdoor unit 10 can release the interlocks of each indoor unit 50 all at once. Details of this configuration will be described later.

[0019] 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. A gas-liquid separator 12, which supplies gaseous refrigerant to the compressor 11, is connected to the suction side of the compressor 11, and a four-way valve 14 is connected to the discharge side of the compressor 11 via an oil separator 13. A high-pressure switch 18, which operates when the pressure in the refrigerant piping 2 exceeds a predetermined value, is provided on the discharge side of the compressor 11. An outdoor heat exchanger 16 is connected to the four-way valve 14. In the outdoor heat exchanger 16, heat exchange takes place between the air supplied by the outdoor fan 15 and the refrigerant circulating through the outdoor heat exchanger 16. An outdoor expansion valve 17 is connected to the downstream side of the outdoor heat exchanger 16.

[0020] 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 controls the operation of the compressor 11, four-way valve 14, outdoor fan 15, outdoor expansion valve 17, etc. Furthermore, a high-voltage switch 18 is connected to the outdoor unit control unit 20. The state of the high-voltage switch 18 is detected by the outdoor unit control unit 20.

[0021] The outdoor unit control unit 20 is connected via a communication line 3 to an indoor unit control unit 60, which is provided in each indoor unit 50 and controls the operation of the indoor unit 50. The outdoor unit control unit 20 communicates with the indoor unit control unit 60 via the communication line 3. Multiple indoor units 50 are connected to the outdoor expansion valve 17 and the four-way valve 14 via refrigerant piping 2.

[0022] Each of the multiple indoor units 50 is equipped with an indoor heat exchanger 52 with an indoor fan 51, an indoor expansion valve 53, a temperature sensor 54 for detecting the temperature of the room in which the indoor unit 50 is installed, a humidity sensor 55 for detecting the humidity of the room in which the indoor unit 50 is installed, and a refrigerant leak sensor 56 for detecting refrigerant leakage. The refrigerant leak 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 the air conditioning operation, setting the air conditioning temperature, displaying the operating status, etc.

[0023] 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 on-off valve 80 and a second on-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.

[0024] The indoor unit control unit 60 controls the operation of the first on-off valve 80, the second on-off valve 81, the indoor fan 51, etc. Detection signals from the temperature sensor 54, the humidity sensor 55, and the refrigerant leak 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 leak 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.

[0025] [1-1-2. Control System Configuration] Next, with reference to Figure 2, the configuration of the control system of the air conditioning system 1 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 this embodiment. 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.

[0026] 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. The socket 22 to which the high-voltage switch 18 is connected corresponds to an example of a "switching circuit". The high-voltage switch 18 corresponds to an example of a "short-circuiting component".

[0027] 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 1.

[0028] On the other hand, as in this embodiment, 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.

[0029] 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. Furthermore, the outdoor unit processor 30 of the outdoor unit control unit 20 is connected to the display mechanism 19.

[0030] The display mechanism 19 is equipped with a display such as an LCD (Liquid Crystal Display) and displays various images on the display according to instructions from the outdoor unit processor 30. The display mechanism 19 displays the first image P1 and the second image P2 on the display according to the instructions of the display control unit 33 of the outdoor unit processor 30. Image 1, P1, corresponds to an example of "First Notification Content". Image 2, P2, corresponds to an example of "Second Notification Content".

[0031] 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.

[0032] The outdoor unit processor 30 is a processor such as a CPU (Central Processing Unit) or MPU (Micro Processing Unit).

[0033] 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).

[0034] 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, a transmission unit 32, and a display control unit 33. Furthermore, the outdoor unit processor 30 reads and executes the outdoor unit program 36 stored in the outdoor unit memory 35, thereby causing the outdoor unit memory 35 to function as a refrigerant storage unit 37. The refrigerant storage unit 37 is stored in a non-volatile memory such as ROM in the outdoor unit memory 35.

[0035] The refrigerant memory unit 37 stores whether the air conditioning unit 1 uses "R410A" or "R32" as the refrigerant. The outdoor unit processor 30 receives an operation from operator W to the operation mechanism (not shown in the figure) and stores in the refrigerant memory unit 37 whether the air conditioner 1 uses the non-flammable refrigerant "R410A" or the flammable refrigerant "R32" as the refrigerant.

[0036] 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". The open state TQ corresponds to an example of the "first state". The short-circuit state TS corresponds to an example of the "second state".

[0037] Furthermore, the state detection unit 31 determines whether or not the power to the outdoor unit 10 has been turned on in the open state TQ. Furthermore, the state detection unit 31 determines whether or not the power to the outdoor unit 10 has been turned on in the short-circuit state TS.

[0038] If the refrigerant storage unit 37 has stored that the air conditioning unit 1 uses "R410A" as a refrigerant, the transmitting unit 32 transmits an interlock release signal SGU to the indoor unit 50.

[0039] Furthermore, if the refrigerant storage unit 37 has stored that the air conditioner 1 uses "R32" as a refrigerant, the transmitting unit 32 transmits an interlock release signal SGU to the indoor unit 50 when the state detection unit 31 detects that the unit is in a short-circuit state TS. The interlock release signal SGU is a signal that instructs the indoor unit 50 to release the interlock.

[0040] Furthermore, if the refrigerant storage unit 37 has stored that the air conditioning system 1 uses "R32" as a refrigerant, the transmitting unit 32 will terminate the transmission of the interlock release signal SGU to the indoor units 50 when it receives a release response signal 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).

[0041] The display control unit 33 displays various images on the display of the display mechanism 19. If the refrigerant storage unit 37 has stored that the air conditioner 1 uses "R410A" as a refrigerant, the display control unit 33 will display the first image P1 on the display of the display mechanism 19 when the state detection unit 31 detects that the state is open (TQ). Furthermore, the detection of an open state TQ by the state detection unit 31 indicates, for example, that the high-voltage switch 18 is not installed in the socket 22.

[0042] Furthermore, if the refrigerant storage unit 37 has stored that the air conditioner 1 uses "R32" as a refrigerant, the display control unit 33 will display the second image P2 on the display of the display mechanism 19 when the state detection unit 31 detects that the state is open (TQ). The second image is different from the first image, P1.

[0043] Image 1 P1 shows, for example, prompting the installation of a high-voltage switch 18 in socket 22 in order to send an interlock release signal SGU to the indoor unit 50.

[0044] The second image P2, for example, shows that the outdoor unit 10 is interlocked. The second image P2 may also show, for example, prompting the user to install the high-voltage switch 18 into the socket 22 in order to release the interlock of the outdoor unit 10. The second image P2 may, for example, show that the high-pressure switch 18 is not installed in the socket 22. Alternatively, the second image P2 may show, for example, a prompt to install the high-pressure switch 18 in the socket 22 in order to drive the compressor 11.

[0045] 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.

[0046] 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.

[0047] 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.

[0048] The indoor unit processor 70 functions as a release reception unit 72 and an execution unit 73 by reading and executing the indoor unit program 76.

[0049] When the release reception unit 72 receives the interlock release signal SGU transmitted from the outdoor unit 10, it receives an instruction to release the interlock for the indoor unit 50. When the release reception unit 72 receives an instruction to release the interlock for the indoor unit 50, it 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.

[0050] 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.

[0051] Furthermore, the release reception unit 72 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".

[0052] 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.

[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 this embodiment will be described. Figure 3 is a diagram showing the arrangement of the connection parts of the high-voltage switch 18 in this embodiment. 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 this embodiment. 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 S115 in Figure 4 are processes performed by the outdoor unit control unit 20 of the outdoor unit 10, and steps S201 to S205 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 S205 shown in Figure 4. Furthermore, the refrigerant storage unit 37 of the outdoor unit control unit 20 of the outdoor unit 10 stores whether the air conditioning system 1 uses "R410A" or "R32" as the refrigerant.

[0057] The outdoor unit control unit 20 of the outdoor unit 10 executes the processes of steps S101 to S111. First, in step S101, the outdoor unit control unit 20 refers to the refrigerant storage unit 37 to determine whether or not the air conditioning system 1 uses "R32" as the refrigerant. If the outdoor unit control unit 20 determines that the air conditioning unit 1 does not use "R32" as a refrigerant (step S101; NO), the process proceeds to step S109. If the outdoor unit control unit 20 determines that the air conditioning unit 1 uses "R32" as a refrigerant (step S101; YES), the process proceeds to step S103.

[0058] Then, in step S103, the state detection unit 31 determines whether or not the power to the outdoor unit 10 has been turned on in the open state TQ. If the state detection unit 31 detects that the outdoor unit 10 is not powered on in the open state TQ (step S103; NO), the process proceeds to step S107. If the state detection unit 31 detects that the outdoor unit 10 is not powered on in the open state TQ (step S103; YES), the process proceeds to step S105. Then, in step S105, the display control unit 33 displays the second image P2 on the display of the display mechanism 19. The second image P2 indicates that the outdoor unit 10 is interlocked.

[0059] Next, in step S107, the state detection unit 31 determines whether or not the power to the outdoor unit 10 has been turned on in the short-circuit state TS. If the state detection unit 31 determines that the outdoor unit 10 is not powered on in a short-circuit state TS (step S107; NO), the process enters a standby state. If the state detection unit 31 determines that the outdoor unit 10 is powered on in a short-circuit state TS (step S107; YES), the process proceeds to step S109.

[0060] Then, in step S109, the display control unit 33 displays on the display of the display mechanism 19 that the outdoor unit 10 is in an interlock release state. Next, in step S111, the transmitting unit 32 transmits an interlock release signal SGU to the indoor unit 50.

[0061] Next, the indoor unit control unit 60 of the indoor unit 50 executes the processes from steps S201 to S205. In step S201, the release reception unit 72 determines whether or not it has received the interlock release signal SGU transmitted from the outdoor unit 10. If the release reception unit 72 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 72 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.

[0062] Then, in step S203, the release reception unit 72 receives an instruction to release the interlock for the indoor unit 50 and changes the release flag 77 from "0" (interlock state STL) to "1" (interlock release state STU). The execution unit 73 also sets the indoor unit 50 to the interlock release state STU, which allows air conditioning operation, when the release flag 77 is changed to "1". Next, in step S205, the release reception unit 72 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.

[0063] Next, the outdoor unit control unit 20 of the outdoor unit 10 executes the processes from steps S113 to S115. First, in step S113, the outdoor unit control unit 20 determines whether or not it has received a release response signal from all indoor units 50. If the outdoor unit control unit 20 determines that it has received a release response signal from all indoor units 50 (step S113; YES), the process proceeds to step S115. If the outdoor unit control unit 20 determines that it has not received a release response signal from all indoor units 50 (step S113; NO), the process returns to step S111.

[0064] Then, in step S115, 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.

[0065] Step S107 corresponds to an example of a "switching step". Step S109 corresponds to an example of the "transmission step". Step S203 corresponds to an example of an "execution step".

[0066] 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 to third conditions.

[0067] Condition 1: A predetermined period of time has elapsed since the interlock release signal SGU was transmitted. 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.

[0068] [1-2-2. Installation Procedure for Air Conditioning Systems] Next, the installation procedure for the air conditioning system 1 will be explained with reference to the process chart shown in Figure 5. Figure 5 is a diagram showing the procedure for installing the air conditioning system 1 in this embodiment. The schedule shown in Figure 5 is for the case of newly installing the air conditioning system 1 and the case of replacing the outdoor unit 10. The procedure for releasing the interlock of the indoor unit 50 is the same as described in the schedule in Figure 5 when adding an indoor unit 50 or when renewing an indoor unit 50. Figure 5 illustrates the case where the air conditioning system 1 uses "R32" as the refrigerant.

[0069] 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 equipment to deal with refrigerant leakage (refrigerant leak sensor 56, alarm, shut-off valve, etc.), 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.

[0070] In the following ninth step, worker W turns on the power to the outdoor unit 10. When the power to the outdoor unit 10 is turned on, the outdoor unit 10 displays a second image P2 indicating that the outdoor unit 10 is interlocked on a display such as an LCD of a display mechanism 19 located on the outdoor unit 10. The worker W confirms the second image P2 displayed on the display, which indicates that the outdoor unit 10 is interlocked. Furthermore, since the plug 182 of the high-voltage switch 18 is not 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 an open state TQ.

[0071] Next, in the tenth step, worker W shuts off the power to the outdoor unit 10. Next, in the 11th 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.

[0072] Next, in step 12, worker W turns the power back on 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 transmission unit 32 of the outdoor unit control unit 20 of the outdoor unit 10 becomes able to transmit an interlock release signal SGU to the indoor unit 50. As described above, worker W performs steps 9 through 11 to release the interlock of the indoor unit 50.

[0073] Next, in step 13, 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 14, 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 step 15, the release reception unit 72 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 accepts an instruction to release the interlock for the indoor unit 50. The release reception unit 72 then 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 then 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.

[0074] Next, in step 16, a circuit inspection is performed. The circuit inspection checks whether the first shut-off valve 80 and the second shut-off valve 81, which are safety devices in case of refrigerant leakage, and the alarm are functioning correctly. For example, the alarm 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 17, worker W uses remote control 90 to deactivate the alarm's error notification. Next, in step 18, worker W performs a test run of the air conditioning system 1, and in step 19, safety measures are completed and the installation work of the air conditioning system 1 is completed.

[0075] [1-3. Effects, etc.] As described above, the air conditioning system 1 comprises an outdoor unit 10 and an indoor unit 50 connected to the outdoor unit 10 by refrigerant piping 2, which can use "R410A" and "R32", a refrigerant that is more flammable than "R410A". The outdoor unit 10 includes a socket 22 that switches between an open state TQ and a short-circuit state TS based on user operation, and a transmitting unit 32 that transmits an interlock release signal SGU to the indoor unit 50 when the socket 22 is in the short-circuit state TS. The indoor unit 50 includes an execution unit 73 that sets the indoor unit 50 to an interlock release state STU when the refrigerant of the air conditioning system 1 is "R410A", allowing air conditioning operation, and sets the indoor unit 50 to an interlock state STL when the refrigerant of the air conditioning system 1 is "R32", and has not received an interlock release signal SGU from the outdoor unit 10, thereby prohibiting air conditioning operation.

[0076] According to the above configuration, when the refrigerant of the air conditioning unit 1 is "R410A", the interlock is released (STU) to allow air conditioning operation of the indoor unit 50, thereby reducing the burden on the worker W during installation. On the other hand, if the refrigerant of the air conditioning unit 1 is "R32", and the interlock release signal SGU is not received from the outdoor unit 10, the indoor unit 50 will be placed in an interlock state STL that prohibits air conditioning operation, thereby ensuring the safety of the worker W during installation work.

[0077] In the above-described air conditioning system 1, the indoor unit 50 is equipped with an acquisition unit 71 that acquires refrigerant information JC indicating the type of refrigerant of the air conditioning system 1. The execution unit 73 sets the interlock release state STU when the acquired refrigerant information JC indicates "R410A", and sets the interlock state STL when the acquired refrigerant information JC indicates "R32" and the interlock release signal SGU has not been received from the outdoor unit 10.

[0078] According to the above configuration, the interlock state STL and the interlock release state STU are switched based on the refrigerant information JC and the interlock release signal SGU, so that the interlock state STL and the interlock release state STU can be switched appropriately.

[0079] In the above-described air conditioning system 1, the socket 22 switches between an open state TQ and a short-circuit state TS based on user operation when the refrigerant of the air conditioning system 1 is "R32". The transmitting unit 32 sends an interlock release signal SGU to the indoor unit 50 when the refrigerant of the air conditioning system 1 is "R410A", and sends an interlock release signal SGU to the indoor unit 50 when the refrigerant of the air conditioning system 1 is "R32" and the socket 22 is in a short-circuit state TS. The execution unit 73 sets the system to an interlock release state STU when it receives an interlock release signal SGU from the outdoor unit 10, and sets the system to an interlock state STL when it does not receive an interlock release signal SGU from the outdoor unit 10.

[0080] According to this, if the refrigerant of the air conditioning unit 1 is "R410A", an interlock release signal SGU is sent to the indoor unit 50, and the indoor unit 50 is set to an interlock release state STU that allows air conditioning operation, thereby reducing the burden on the worker W during installation work. On the other hand, if the refrigerant of the air conditioning unit 1 is "R32" and the socket 22 is in a short-circuit state TS, an interlock release signal SGU is sent to the indoor unit 50, and when the execution unit 73 receives the interlock release signal SGU from the outdoor unit 10, it sets the unit to an interlock release state STU, thereby ensuring the safety of the worker W during installation work.

[0081] In the above-described air conditioning system 1, the outdoor unit 10 includes a display mechanism 19 for displaying information, and a display control unit 33 for displaying refrigerant information JC indicating the type of refrigerant on the display mechanism 19.

[0082] According to this, the display control unit 33 displays refrigerant information JC indicating the type of refrigerant on the display mechanism 19, so that the operator W can easily see the type of refrigerant. Therefore, the convenience of the operator W can be improved.

[0083] In the above-described air conditioning system 1, the outdoor unit 10 includes a display mechanism 19 for displaying information and a display control unit 33 for displaying an image on the display mechanism 19. The socket 22 is in an open state TQ when the high-pressure switch 18 is not installed in the socket 22, and in a short-circuit state TS when the high-pressure switch 18 is installed in the socket 22. The display control unit 33 displays a first image P1 on the display mechanism 19 when the refrigerant used by the air conditioning system 1 is "R410A" because the high-pressure switch 18 is not installed, and displays a second image P2 on the display mechanism 19 that is different from the first image P1 when the refrigerant used by the air conditioning system 1 is "R32" because the high-pressure switch 18 is not installed.

[0084] According to this, the convenience of the worker W can be improved by appropriately setting each of the first image P1 and the second image P2. If the first image P1 indicates, for example, that the high-voltage switch 18 should be installed in the socket 22 in order to send an interlock release signal SGU to the indoor unit 50, then the worker W can visually confirm that the high-voltage switch 18 needs to be installed in the socket 22 in order to send the interlock release signal SGU. Furthermore, if the second image P2 indicates, for example, that the high-voltage switch 18 should be installed on the socket 22 in order to release the interlock of the outdoor unit 10, then the worker W can visually confirm that the high-voltage switch 18 needs to be installed on the socket 22 in order to release the interlock of the outdoor unit 10.

[0085] The control method for the air conditioning system 1 comprises an outdoor unit 10 and an indoor unit 50 connected to the outdoor unit 10 by refrigerant piping 2, which can use "R410A" and "R32", a refrigerant that is more flammable than "R410A". outdoor unit 10 performs a switching step of switching between an open state TQ and a short-circuit state TS based on user operation, and a transmission step of sending an interlock release signal SGU to the indoor unit 50 if the switching step is in the short-circuit state TS. The indoor unit 50 performs an execution step of setting the indoor unit 50 to an interlock release state STU if the refrigerant of the air conditioning system 1 is "R410A", which allows air conditioning operation of the indoor unit 50, and setting the indoor unit 50 to an interlock state STL if the refrigerant of the air conditioning system 1 is "R32", which does not receive an interlock release signal SGU from the outdoor unit 10.

[0086] According to this, the control method for the air conditioning system 1 produces the same effects as the air conditioning system 1 described above.

[0087] (modified version) [2-1. Variations of the switching circuit] In the embodiments described with reference to Figures 1 to 5, the case where the "switching circuit" is a socket 22 to which the high-voltage switch 18 is connected was described, but this disclosure is not limited to this. For example, the outdoor unit 10 may be configured to include a dedicated component for releasing the interlock of the indoor unit 50.

[0088] Figure 6 shows a modified configuration in which the outdoor unit 10 is equipped with a component specifically for releasing the interlock of the indoor unit 50. In Figure 6, the circuit board 150 on which the electronic components constituting the outdoor unit control unit 20 are mounted is shown as an example in which a short-circuit pin 173 is provided as a component specifically for releasing the interlock of the indoor unit 50. The short-circuit pin 173 is in an open state TQ when the header 174 is not installed, and in a short-circuit state TS when the header 174 is installed. In this case, the state detection unit 31 detects whether the short-circuit pin 173 is in a short-circuit state TS or an open state TQ.

[0089] The substrate 150 is divided into areas 160 and 180 used when replacing components, and area 170 used during installation. The shorting pin 173 is mounted in area 170, and in addition to the shorting pin 173, area 170 also mounts a 7-segment LED (Light Emitting Diode) 171 and an operation button 172. To prevent the header 174 from falling off, a fall prevention member that accommodates or holds the header 174 may be provided on the substrate 150 or near the location where the substrate 150 is placed. The fall prevention member is, for example, a tray provided at the bottom of the substrate 150.

[0090] In the modified configuration shown in Figure 6, for example, the operation of pulling out the header 174 from the short-circuit pin 173 is the operation of releasing the interlock of the indoor unit 50. Shorting pin 173 corresponds to an example of a "switching circuit". The fact that the short-circuit pin 173 is in a short-circuit state TS corresponds to an example of the "first state". Furthermore, the fact that the short-circuit pin 173 is in the open state TQ corresponds to an example of the "second state".

[0091] In the modified configuration shown in Figure 6, for example, the operation of inserting the header 174 from the short-circuit pin 173 may also be the operation of releasing the interlock of the indoor unit 50. In this case, the short-circuit pin 173 being in an open state TQ corresponds to an example of the "first state." Also, the short-circuit pin 173 being in a short-circuit state TS corresponds to an example of the "second state."

[0092] [2-2. Modified Control Units] Next, referring to Figure 2, modified forms of the outdoor unit control unit 20 and the indoor unit control unit 60 will be described. In the embodiment described with reference to Figures 1 to 5, the transmitting unit 32 transmits an interlock release signal SGU to the indoor unit 50 if the refrigerant storage unit 37 has stored that the air conditioner 1 uses "R410A" as the refrigerant; however, the embodiment is not limited to this. The following description will mainly focus on the differences between the configuration of the outdoor unit control unit 20 and the indoor unit control unit 60 in the embodiment described with reference to Figures 1 to 5.

[0093] For example, the transmitting unit 32 may receive an operation by operator W on an operating mechanism (not shown in the figure) and transmit refrigerant information JC, which indicates the type of refrigerant used in the air conditioning system 1, to the indoor unit 40. In this case, the indoor unit control unit 60 further comprises an acquisition unit 71 and a refrigerant storage unit 78. In other words, the indoor unit processor 70 functions as an acquisition unit 71, a release acceptance unit 72, and an execution unit 73 by reading and executing the indoor unit program 76. Furthermore, by reading and executing the indoor unit program 76, the indoor unit processor 70 causes the indoor unit memory 75 to function as a refrigerant storage unit 78.

[0094] The acquisition unit 71 acquires refrigerant information JC from the outdoor unit 10, which indicates the type of refrigerant used in the air conditioning system 1. The refrigerant information JC indicates, for example, whether the refrigerant is "R32" or "R410A". The refrigerant storage unit 78 stores the refrigerant information JC acquired by the acquisition unit 71. The acquisition unit 71 causes the refrigerant information JC acquired by the acquisition unit 71 to be stored in the refrigerant storage unit 78.

[0095] The release reception unit 72 receives an instruction to release the interlock for the indoor unit 50 when the refrigerant information acquisition unit 71 acquires refrigerant information JC indicating that the refrigerant is "R410A". When the release reception unit 72 receives an instruction to release the interlock for the indoor unit 50, it 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.

[0096] 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.

[0097] [2-3. Variations of the outdoor unit] In the above embodiment, a case was described in which there is one outdoor unit 10 constituting the air conditioning system 1, but this disclosure is not limited thereto.

[0098] Figure 7 shows a modified configuration of the air conditioning system 1, which includes a first outdoor unit 10a and a second outdoor unit 10b. The configuration of the first outdoor unit 10a is the same as that of the outdoor unit 10 described with reference to Figures 1 and 2. The configuration of the second outdoor unit 10b will be described with reference to Figure 7. Furthermore, the first outdoor unit 10a functions as the master unit, and the second outdoor unit 10b functions as the slave unit. In Figure 7, for configurations similar to those of the outdoor unit 10, the same reference numerals are used, with "a" added for the first outdoor unit 10a and "b" added for the second outdoor unit 10b, thereby omitting detailed explanations.

[0099] The outdoor unit processor 30b of the second outdoor unit 10b functions as a state detection unit 31b and a transmission unit 32b. The state detection unit 31b detects the state between the connection terminals 221b and 222b of the socket 22b to which the plug 182b of the high-voltage switch 18b is connected (short circuit state TS or open circuit state TQ). The transmitting unit 34 transmits a second state detection signal to the first outdoor unit 10a, which indicates the result of the state detection unit 31b detecting the state of the terminals of the socket 22b.

[0100] The state detection unit 31a of the first outdoor unit 10a receives a second state detection signal transmitted from the transmission unit 34 of the second outdoor unit 10b via communication with the second outdoor unit 10b when the power to the first outdoor unit 10a and the second outdoor unit 10b is turned on. Then, the state detection unit 31a detects from the second state detection signal that the socket 22b of the second outdoor unit 10b is in a short-circuit state TS, and when the state detection unit 31a also detects that the socket 22a of the first outdoor unit 10a is in a short-circuit state TS, it detects that the unit is in a short-circuit state TS. Furthermore, the state detection unit 31a detects from the second state detection signal that the socket 22b of the second outdoor unit 10b is in the open state TQ, and when the state detection unit 31a detects that the socket 22a of the first outdoor unit 10a is in the open state TQ, it detects that the socket is in the open state TQ.

[0101] Furthermore, the transmitter 32a of the first outdoor unit 10a, similar to the transmitter 32 of the outdoor unit 10 described with reference to Figures 1 and 2, transmits an interlock release signal SGU to the indoor unit 50 if the refrigerant storage unit 37 has stored that the air conditioning system 1 uses "R410A" as a refrigerant. Furthermore, the transmitting unit 32a of the first outdoor unit 10a, similar to the transmitting unit 32 of the outdoor unit 10 described with reference to Figures 1 and 2, transmits an interlock release signal SGU to the indoor unit 50 when the state detection unit 31 detects that the air conditioning system 1 is in a short-circuit state TS, provided that the refrigerant storage unit 37 has stored that the air conditioning system 1 uses "R32" as a refrigerant.

[0102] In this case, when installing the first outdoor unit 10a and the second outdoor unit 10b during the initial installation of the air conditioning system 1, the master unit, the first outdoor unit 10a, only needs to send an interlock release signal SGU to each of the indoor units 50, and the slave unit, the second outdoor unit 10b, does not need to send an interlock release signal SGU to each of the indoor units 50. Therefore, it is possible to avoid duplicate transmission of the interlock release signal SGU from the second outdoor unit 10b of the slave unit to each of the indoor units 50, thereby reducing the amount of communication.

[0103] (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.

[0104] In the above embodiment, a socket 22 for connecting a high-voltage switch 18 is exemplified as the "switching circuit" of this disclosure, but the "switching circuit" is not limited to this. The "switching circuit" only needs to have a configuration that switches between a short-circuit state TS and an open-circuit state TQ based on the operation of the worker W, for example. For example, in the outdoor unit 10, another component having output contacts similar to the high-voltage switch 18 may be used as the "switching circuit".

[0105] Furthermore, for example, a component of the outdoor unit 10 used to release the interlock of the indoor unit 50, such as a high-voltage switch 18, may be provided, or near this component, with a marking indicating that an instruction to perform the interlock release operation should be provided. The indicated component may be installed, for example, after the installation of safety devices (e.g., refrigerant leak sensor 56, alarm, shut-off valve, etc.). Furthermore, the indicated components will include instructions for performing an interlock release operation, such as, "After confirming the connection of the safety device, insert the connector into the outdoor unit circuit board to release the interlock." In addition to the high-voltage switch 18, various sensors such as temperature sensors and pressure sensors can be used as components of the outdoor unit 10 used to release the interlock.

[0106] 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).

[0107] 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.

[0108] In the flowchart shown in Figure 4, 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, and 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.

[0109] 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.

[0110] (Note) Based on the above description of embodiments, the following technologies are disclosed.

[0111] (Technology 1) An air conditioning system comprising an outdoor unit and an indoor unit connected to the outdoor unit by refrigerant piping, which can use a first refrigerant and a second refrigerant that is more flammable than the first refrigerant, wherein the outdoor unit comprises a switching circuit that switches between a first state and a second state different from the first state based on user operation, and a transmitting unit that transmits an interlock release signal to the indoor unit when the switching circuit is in the second state, and an execution unit that sets the indoor unit to an interlock release state that permits air conditioning operation when the refrigerant of the air conditioning system is the first refrigerant, and sets the indoor unit to an interlock state that prohibits air conditioning operation when the refrigerant of the air conditioning system is the second refrigerant and has not received an interlock release signal from the outdoor unit, the air conditioning system.

[0112] With this configuration, if the refrigerant of the air conditioning system is the first refrigerant, the interlock is released to allow the indoor unit to operate, thus reducing the burden on workers during installation. On the other hand, if the second refrigerant, which is more flammable than the first refrigerant of the air conditioning system, is used, the interlock is released to prohibit the indoor unit from operating when the interlock release signal has not been received from the outdoor unit, thus ensuring the safety of workers W during installation.

[0113] (Technology 2) The air conditioning system according to Technical 1, wherein the indoor unit includes an acquisition unit that acquires refrigerant information indicating the type of refrigerant of the air conditioning system, and the execution unit sets the interlock release state when the acquired refrigerant information indicates the first refrigerant, and sets the interlock state when the acquired refrigerant information indicates the second refrigerant and has not received an interlock release signal from the outdoor unit.

[0114] With this configuration, the interlock state L and the interlock release state are switched based on refrigerant information indicating the type of refrigerant and an interlock release signal, thereby enabling proper switching between the interlock state and the interlock release state.

[0115] (Technology 3) The air conditioning system according to Technical 1, wherein the switching circuit switches between the first state and the second state based on user operation when the refrigerant of the air conditioning system is the second refrigerant, the transmitting unit transmits an interlock release signal to the indoor unit when the refrigerant of the air conditioning system is the first refrigerant, the transmitting unit transmits an interlock release signal to the indoor unit when the refrigerant of the air conditioning system is the second refrigerant and the switching circuit is in the second state, and the executing unit sets to the interlock release state when it receives an interlock release signal from the outdoor unit, and sets to the interlock state when it does not receive an interlock release signal from the outdoor unit.

[0116] With this configuration, if the refrigerant of the air conditioning system is the first refrigerant, an interlock release signal is sent to the indoor unit, and when the execution unit receives the interlock release signal from the outdoor unit, it is set to the interlock release state, thereby reducing the burden on the worker W during installation work. On the other hand, if the refrigerant used in the air conditioning system is a secondary refrigerant, the system will enter an interlock state that prohibits the indoor unit from operating when an interlock release signal has not been received from the outdoor unit, thereby ensuring the safety of workers during installation.

[0117] (Technology 4) The air conditioning system according to any one of the technologies 1 to 3, wherein the outdoor unit comprises a display mechanism for displaying information and a display control unit for displaying refrigerant information indicating the type of refrigerant on the display mechanism.

[0118] With this configuration, the display mechanism shows refrigerant information indicating the type of refrigerant, allowing operators to easily identify the type of refrigerant. Therefore, operator convenience can be improved.

[0119] (Technology 5) The air conditioning system according to any one of the technologies 1 to 3, wherein the outdoor unit comprises a display mechanism for displaying information and a display control unit for displaying an image on the display mechanism, the switching circuit is in the first state when a short-circuit member is not installed on the switching circuit, and is in the second state when the short-circuit member is installed on the switching circuit, the display control unit displays a first notification on the display mechanism due to the short-circuit member being not installed when the refrigerant used by the air conditioning system is a first refrigerant, and displays a second notification on the display mechanism that is different from the first notification on the display mechanism due to the short-circuit member being not installed when the refrigerant used by the air conditioning system is a second refrigerant.

[0120] This configuration allows for improved convenience for workers by appropriately setting the content of both the first and second notifications. If the content of the first notification indicates, for example, that a short-circuiting component should be installed in the switching circuit in order to send an interlock release signal to the indoor unit, then the worker should be able to visually confirm that a short-circuiting component needs to be installed in the switching circuit in order to send an interlock release signal. Furthermore, if the second notification indicates, for example, that a short-circuiting component should be installed in the switching circuit to release the interlock of the outdoor unit, then the worker will be able to visually confirm that a short-circuiting component needs to be installed in the switching circuit to release the interlock of the outdoor unit.

[0121] (Technology 6) A control method for an air conditioning system comprising an outdoor unit and an indoor unit connected to the outdoor unit by refrigerant piping, which can use a first refrigerant and a second refrigerant that is more flammable than the first refrigerant, wherein the outdoor unit performs a switching step of switching between a first state and a second state different from the first state based on user operation, and a transmitting step of sending an interlock release signal to the indoor unit if the outdoor unit is in the second state in the switching step, and the indoor unit performs an execution step of setting the indoor unit to an interlock release state that permits air conditioning operation if the refrigerant of the air conditioning system is the first refrigerant, and setting the indoor unit to an interlock state that prohibits air conditioning operation if the refrigerant of the air conditioning system is the second refrigerant and the indoor unit has not received an interlock release signal from the outdoor unit.

[0122] This configuration produces the same effect as the air conditioning system of Technology 1. [Industrial applicability]

[0123] This disclosure is applicable to applications that reduce the burden on workers during installation work when the indoor unit can use a first refrigerant and a second refrigerant which is more flammable than the first refrigerant. [Explanation of Symbols]

[0124] 1. Air conditioning system 10 Outdoor unit 18. High-voltage switch (short-circuiting component) 19 Display mechanism 182 plug 20 Outdoor unit control unit 21 Indoor unit communication circuit 22 Sockets (Switching Circuit) 30 Outdoor Unit Processor 31 State detection unit 32 Transmitter 33 Display Control Unit 35 Outdoor unit memory 36 Outdoor Unit Program 37 Refrigerant storage unit 50 Indoor unit 60 Indoor Unit Control Unit 61 Indoor unit communication circuit 70 Indoor Unit Processor 71 Acquisition Department 72 Cancellation Request Department 73 Execution Department 75 Indoor unit memory 76 Indoor Unit Program 77 Release Flag (Interlock Release Information) 78 Refrigerant storage unit 90 Remote Control P1 First image (First notification content) P2 Second image (Second notification content) SGU Interlock Release Signal STL Interlock Status STU Interlock Released State TQ open state (first state) TS short-circuit condition (second state) W Worker (User)

Claims

1. An air conditioning system comprising an outdoor unit and an indoor unit connected to the outdoor unit by refrigerant piping, which can use a first refrigerant and a second refrigerant that is more flammable than the first refrigerant, The aforementioned outdoor unit is, A switching circuit that switches between a first state and a second state different from the first state based on user operation, When the switching circuit is in the second state, the transmitting unit transmits an interlock release signal to the indoor unit, Equipped with, The aforementioned indoor unit is If the refrigerant of the air conditioning system is the first refrigerant, the execution unit sets the interlock to a release state that allows the indoor unit to operate. If the refrigerant of the air conditioning system is the second refrigerant, and the execution unit has not received an interlock release signal from the outdoor unit, the execution unit sets the interlock to a state that prohibits the indoor unit from operating. An air conditioning system equipped with the following features.

2. The aforementioned indoor unit is The system includes an acquisition unit that acquires refrigerant information indicating the type of refrigerant used in the aforementioned air conditioning system. The execution unit shall, if the acquired refrigerant information indicates the first refrigerant, set the interlock to the unlocked state, and if the acquired refrigerant information indicates the second refrigerant, set the interlock to the unlocked state if it has not received an interlock release signal from the outdoor unit. The air conditioning device according to claim 1.

3. The switching circuit switches between the first state and the second state based on user operation when the refrigerant of the air conditioner is the second refrigerant. The transmitting unit transmits an interlock release signal to the indoor unit when the refrigerant of the air conditioner is the first refrigerant, and transmits an interlock release signal to the indoor unit when the refrigerant of the air conditioner is the second refrigerant and the switching circuit is in the second state. The execution unit shall, when it receives an interlock release signal from the outdoor unit, set the unit to the interlock release state, and when it does not receive an interlock release signal from the outdoor unit, set the unit to the interlock state. The air conditioning device according to claim 1.

4. The aforementioned outdoor unit is, A display mechanism for displaying information, The display mechanism includes a display control unit that displays refrigerant information indicating the type of refrigerant, An air conditioning device according to any one of claims 1 to 3, comprising:

5. The aforementioned outdoor unit is, A display mechanism for displaying information, The display mechanism includes a display control unit that displays an image, Equipped with, The switching circuit is in the first state when the short-circuiting member is not installed in the switching circuit, and in the second state when the short-circuiting member is installed in the switching circuit. The display control unit, When the refrigerant used by the air conditioning system is the first refrigerant, the display mechanism displays the first notification content due to the short-circuiting member not being installed. When the refrigerant used by the air conditioning system is the second refrigerant, the display mechanism displays a second notification that differs from the first notification due to the short-circuiting member not being installed. An air conditioning device according to any one of claims 1 to 3.

6. A control method for an air conditioning system having an outdoor unit and an indoor unit connected to the outdoor unit by refrigerant piping, which can use a first refrigerant and a second refrigerant that is more flammable than the first refrigerant, The aforementioned outdoor unit is, A switching step that switches between a first state and a second state different from the first state based on user operation, If the second state is reached in the switching step, a transmission step is performed to transmit an interlock release signal to the indoor unit, Execute, The aforementioned indoor unit is If the refrigerant of the air conditioning system is the first refrigerant, the system is set to an interlock release state that allows the indoor unit to operate; if the refrigerant of the air conditioning system is the second refrigerant, and an interlock release signal has not been received from the outdoor unit, the system is set to an interlock state that prohibits the indoor unit from operating. Execute A method for controlling an air conditioning system.

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