Air conditioning system and control method for air conditioning system

Abstract

This disclosure provides an air conditioning system that can improve safety when indoor units are added or refurbished. [Solution] An air conditioning system having an outdoor unit and an indoor unit, wherein the outdoor unit includes a setting unit that sets whether or not to send an interlock release signal to the indoor unit depending on whether or not predetermined conditions are met, and a transmitting unit that sends the interlock release signal to the indoor unit according to the setting result of the setting unit, and the indoor unit includes an execution unit that sets the indoor unit to an interlock release state that allows air conditioning operation of the indoor unit when it receives the interlock release signal from the outdoor unit, and sets the indoor unit to an interlock state that prohibits air conditioning operation of the indoor unit when it has not received the interlock release signal from the outdoor unit, and the setting unit sets the interlock release signal to be untransmittable after the transmitting unit has sent the interlock release signal to the indoor unit for a predetermined period of time.

Description

Technical Field

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

Background Art

[0002] Patent Document 1 discloses an air conditioner that includes a plurality of indoor units having an 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 thereof that can improve safety when an indoor unit is added or renewed.

Means for Solving the Problems

[0005] The air conditioning system in this disclosure is an air conditioning system having an outdoor unit and an indoor unit that are connected to each other in a manner that allows communication between them, wherein the outdoor unit includes a setting unit that sets whether or not to send an interlock release signal to the indoor unit depending on whether or not predetermined conditions are met, and a transmitting unit that transmits the interlock release signal to the indoor unit according to the setting result of the setting unit, wherein the indoor unit includes an execution unit that sets the indoor unit to an interlock release state that allows air conditioning operation when it receives the interlock release signal from the outdoor unit, and sets the indoor unit to an interlock state that prohibits air conditioning operation when it has not received the interlock release signal from the outdoor unit, wherein the setting unit sets the interlock release signal to be untransmittable after the transmitting unit has transmitted the interlock release signal to the indoor unit for a predetermined period of time,

[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, wherein the outdoor unit performs a setting step of setting whether or not to send an interlock release signal to the indoor unit depending on whether or not predetermined conditions are met, and a transmission step of sending the interlock release signal to the indoor unit according to the setting result in the setting step, and the indoor unit performs an interlock control step of setting the indoor unit to an interlock release state that allows air conditioning operation of the indoor unit when it receives the interlock release signal from the outdoor unit, and setting the indoor unit to an interlock state that prohibits air conditioning operation of the indoor unit when it has not received the interlock release signal from the outdoor unit, and in the setting step, after sending the interlock release signal to the indoor unit for a predetermined period of time in the transmission step, the transmission of the interlock release signal is set to not be possible. [Effects of the Invention]

[0007] The air conditioning system and control method for the air conditioning system described herein can improve safety when indoor units are added or replaced. [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] This figure shows another example of the procedure for installing the air conditioning system in the embodiment. [Figure 7] 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 8] 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, if the interlock is released on the outdoor unit, there is a possibility that the interlock release operation will not be repeated when an indoor unit is added or replaced. For example, if the interlock is released by inserting a high-voltage switch, there is a possibility that the high-voltage switch will not be inserted or removed when an indoor unit is added or replaced. In that case, even if the safety device of the added or replaced indoor unit is not inspected, it will be able to operate, leaving room for improvement in safety. In other words, the inventors identified a problem in improving safety when indoor units are added or replaced, 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 improve safety when indoor units are added or refurbished.

[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 6. [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, a case where the air conditioner 1 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.

[0015] Before the start of use, the indoor unit 50 is in an interlock state in which air conditioning operation is prohibited. An operator W who installs 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 has a configuration that enables the interlocks of each indoor unit 50 to be released collectively by operating the outdoor unit 10 in order to facilitate the operation of releasing the interlock of the indoor unit 50 by the operator W. Details of such a configuration will be described later. The operator W corresponds to an example of a "user".

[0016] 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 that supplies 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.

[0017] 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. 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.

[0018] 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.

[0019] 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.

[0020] 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.

[0021] 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.

[0022] [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.

[0023] 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".

[0024] 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.

[0025] 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.

[0026] 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.

[0027] 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.

[0028] The outdoor unit processor 30 is a processor such as a CPU (Central Processing Unit) or MPU (Micro Processing Unit).

[0029] 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).

[0030] Figures 2-5 and 7-8 illustrate the case where the indoor unit 50 is added or replaced. 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 setting unit 32, and a transmission 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 history storage unit 37. The history storage unit 37 is stored in the non-volatile memory of the outdoor unit memory 35, such as ROM.

[0031] The history storage unit 37 stores the ON / OFF history of the outdoor unit 10's power and the history of the detection results of the state detection unit 31. In other words, the history storage unit 37 stores information indicating whether the power of the outdoor unit 10 is switched ON or OFF, and the date and time information of when the power of the outdoor unit 10 was switched ON or OFF, in association with each other. The history storage unit 37 also stores the detection result of the state detection unit 31, that is, information indicating whether the connection terminals 221 and 222 of the socket 22 are in a short-circuit state TS or an open state TQ, in association with the date and time information of when the detection result of the state detection unit 31 changed.

[0032] Information indicating whether the outdoor unit 10's power is turned ON or OFF, and information regarding the date and time when the power of the outdoor unit 10 was turned ON or OFF, are stored in the history storage unit 37 by the outdoor unit processor 30. Furthermore, information indicating whether the connection terminals 221 and 222 of socket 22 are in a short-circuit state (TS) or an open state (TQ), and information regarding the date and time when the detection result of the state detection unit 31 changed, are stored in the history storage unit 37 by the state detection unit 31.

[0033] Furthermore, the information stored in the history storage unit 37 is erased by the transmission unit 33. The information stored in the history storage unit 37 is erased by the transmission unit 33, for example, when the transmission of the interlock release signal SGU to the indoor unit 50 is completed.

[0034] 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".

[0035] Furthermore, when the state detection unit 31 changes from a short-circuit state TS to an open-circuit state TQ, it associates information indicating that the state has changed from a short-circuit state TS to an open-circuit state TQ with date and time information and stores it in the history storage unit 37.

[0036] The setting unit 32 sets whether or not to send an interlock release signal SGU to the indoor unit 50. The setting unit 32, for example, refers to the history storage unit 37 and sets the system to enable sending the interlock release signal SGU to the indoor unit 50 if all of the following first condition CD1, second condition CD2, and third condition CD3 are met. The setting unit 32 also refers to the history storage unit 37 and sets the system to disable sending the interlock release signal SGU to the indoor unit 50 if at least one of the following first condition CD1, second condition CD2, and third condition CD3 is not met.

[0037] Condition 1 CD1: The power to the outdoor unit 10 was turned on while the unit was in the open state TQ. Second condition CD2: After the first condition CD1 is met, the power to the outdoor unit 10 is restored while it is in a short-circuit state TS. Third condition CD3: After the first condition CD1 is met, the power to the outdoor unit 10 is turned on for the first time while it is in a short-circuit state TS. In other words, the "re-on" of the power in the second condition CD2 is the first power-on while it is in a short-circuit state TS. Furthermore, when the outdoor unit 10 is powered on while the gate is in the open state TQ, the setting unit 32 outputs an alarm indicating that the outdoor unit 10 is interlocked. The first condition CD1, the second condition CD2, and the third condition CD3 correspond to examples of "predetermined conditions."

[0038] Furthermore, the setting unit 32 sets the interlock release signal SGU to be disabled when a predetermined period PD (for example, several tens of minutes) has elapsed since the transmission unit 33 transmitted the interlock release signal SGU. The specified period PD can be set according to, for example, the number of indoor units 50. This is because the more indoor units 50 there are, the longer the work time will be.

[0039] The transmitting unit 33 transmits the interlock release signal SGU to the indoor unit 50 when the setting unit 32 has set it to be possible to transmit the interlock release signal SGU to the indoor unit 50. The interlock release signal SGU is a signal that instructs the indoor unit 50 to release the interlock.

[0040] Furthermore, the transmitting unit 33 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).

[0041] Furthermore, the transmitting unit 33 terminates the transmission of the interlock release signal SGU to the indoor unit 50 when the setting unit 32 has set that it is not possible to transmit the interlock release signal SGU to the indoor unit 50. Furthermore, when the transmitting unit 33 finishes transmitting the interlock release signal SGU to the indoor unit 50, it erases the information stored in the history storage unit 37.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] The indoor unit processor 70 functions as a release reception unit 71 and an execution unit 72 by reading and executing the indoor unit program 76.

[0046] When the release reception unit 71 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 71 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.

[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 release reception unit 71 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 72 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 72 sets the interlock release state STU to allow air conditioning operation of the indoor unit 50.

[0050] [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.

[0051] 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.

[0052] [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.

[0053] 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 history storage unit 37 of the outdoor unit control unit 20 of the outdoor unit 10 stores the history of when the outdoor unit 10's power is turned ON / OFF, and the history of the detection results of the state detection unit 31 (i.e., information indicating whether it is in a short-circuit state TS or an open-circuit state TQ).

[0054] The outdoor unit control unit 20 of the outdoor unit 10 executes the processes from steps S101 to S109. First, in step S101, the setting unit 32 refers to the history storage unit 37 to determine whether the power to the outdoor unit 10 was turned on in the open state TQ. In other words, the setting unit 32 determines whether the "first condition CD1" described with reference to Figure 2 is met. If the setting unit 32 determines that the outdoor unit 10 is not powered on in the open state TQ (step S101; NO), the process enters a standby state. If the setting unit 32 determines that the outdoor unit 10 is powered on in the open state TQ (step S101; YES), the outdoor unit 10 outputs an alarm indicating that it is interlocked, and the process proceeds to step S103.

[0055] Then, in step S103, the setting unit 32 refers to the history storage unit 37 and determines whether the power to the outdoor unit 10 was restored in the short-circuit state TS. In other words, the setting unit 32 determines whether the "second condition CD2" described with reference to Figure 2 is met. If the setting unit 32 determines that the power to the outdoor unit 10 has not been restored while the short circuit state TS is active (step S103; NO), the process enters a standby state. If the setting unit 32 determines that the power to the outdoor unit 10 has been restored while the short circuit state TS is active (step S103; YES), the process proceeds to step S105.

[0056] Then, in step S105, the setting unit 32 refers to the history storage unit 37 and determines whether the power-on in step S103 is the first power-on. In other words, the setting unit 32 determines whether the "third condition CD3" explained with reference to Figure 2 is met. If the setting unit 32 determines that the power-on in step S103 is not the first power-on (step S105; NO), the process returns to step S101. If the setting unit 32 determines that the power-on in step S103 is the first power-on (step S105; YES), the process proceeds to step S107.

[0057] Then, in step S107, the setting unit 32 sets it so that it can send the interlock release signal SGU to the indoor unit 50. Next, in step S109, the transmitting unit 33 transmits an interlock release signal SGU to the indoor unit 50.

[0058] 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 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.

[0059] Then, in step S203, the release reception unit 71 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 72 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 71 transmits 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.

[0060] Next, the outdoor unit control unit 20 of the outdoor unit 10 executes the processes of steps S111 to S115. First, in step S111, the transmitting unit 33 determines whether or not it has received a release response signal from all indoor units 50. In step S111, "all indoor units 50" refers to all indoor units 50 that have been added or replaced. If the transmitter 33 determines that it has received a release response signal from all indoor units 50 (step S111; YES), the process proceeds to step S115. If the transmitter 33 determines that it has not received a release response signal from all indoor units 50 (step S111; NO), the process proceeds to step S113.

[0061] Then, in step S113, the setting unit 32 determines whether a predetermined period of PD has elapsed since the time when the transmission unit 33 transmitted the interlock release signal SGU in step S109. If the setting unit 32 determines that a predetermined period of PD has not elapsed since the interlock release signal SGU was transmitted (step S113; NO), the process returns to step S111. If the setting unit 32 determines that a predetermined period of PD has elapsed since the interlock release signal SGU was transmitted (step S113; YES), the setting unit 32 sets the interlock release signal SGU to be disabled, and the process proceeds to step S115.

[0062] Then, in step S115, the transmitting unit 33 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.

[0063] Steps S101 to S107 correspond to an example of a "setting step". Step S109 corresponds to an example of the "transmission step". Step S203 corresponds to an example of an "execution step".

[0064] In the flowchart shown in Figure 4, the conditions for ending the transmission of the interlock release signal SGU by the transmitting unit 33 are that release response signals have been received from all indoor units 50, and that a predetermined period PD has elapsed since the time the interlock release signal SGU was transmitted. However, the conditions for ending the transmission of the interlock release signal SGU are not limited to these. The conditions for ending the transmission of the interlock release signal SGU by the transmitting unit 33 may include, for example, the reception of release response signals from all indoor units 50 and the elapsed of a predetermined period PD from the time the interlock release signal SGU was transmitted, as well as other conditions such as the following fourth and fifth conditions.

[0065] Condition 4: 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. Condition 5: 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 can realize that the interlock of the indoor unit 50 has not been released.

[0066] [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 a schedule corresponding to the case where an additional indoor unit 50 is added and the case where an indoor unit 50 is replaced.

[0067] In the process chart shown in Figure 5, in the first step, worker W installs the indoor unit 50 with the outdoor unit 10 already installed, 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.

[0068] 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, an alarm is output indicating that the outdoor unit 10 is interlocked. The outdoor unit 10 displays the alarm indicating that the outdoor unit 10 is interlocked on a display such as an LCD (Liquid Crystal Display) located on the outdoor unit 10. Worker W confirms the alarm indicating that the outdoor unit 10 is interlocked displayed on the display. 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. As a result, the "first condition CD1" described with reference to Figure 2 is met.

[0069] 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.

[0070] 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 "second condition CD2" and "third condition CD3" explained with reference to Figure 2 are met. Therefore, the setting unit 32 of the outdoor unit control unit 20 of the outdoor unit 10 is set to be able to send the 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.

[0071] 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 33 transmits an interlock release signal SGU to the indoor unit 50. Next, in step 15, 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 accepts an instruction to release the interlock for the indoor unit 50. The release reception unit 71 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 72 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.

[0072] 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.

[0073] Next, the installation procedure for the air conditioning system 1 will be described with reference to the process chart shown in Figure 6. Figure 6 is a diagram showing another example of the installation procedure for the air conditioning system 1 in this embodiment. The schedule shown in Figure 6 is for cases where an air conditioning system 1 is newly installed and when an outdoor unit 10 is replaced. On the other hand, when an indoor unit 50 is added or when an indoor unit 50 is refurbished, the interlock release work for the indoor unit 50 is performed according to the schedule in Figure 5.

[0074] In the process chart shown in Figure 6, 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 6, 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.

[0075] In the following 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.

[0076] 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 setting unit 32 of the outdoor unit control unit 20 of the outdoor unit 10 sets it to be able to send an interlock release signal SGU to the indoor unit 50. As described above, worker W performs steps 9 and 10 to release the interlock of the indoor unit 50.

[0077] 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 33 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. The release reception unit 71 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 72 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.

[0078] Next, in step 14, 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 15, worker W uses remote control 90 to deactivate the alarm's error notification. Next, in step 16, worker W performs a test run of the air conditioning system 1, and in step 17, safety measures are completed and the installation work of the air conditioning system 1 is completed.

[0079] As explained with reference to Figure 6, when installing a new air conditioning unit 1 or replacing the outdoor unit 10, worker W performs steps 9 and 10 to release the interlock of the indoor unit 50. Therefore, compared to when adding an indoor unit 50 or renewing an indoor unit 50 as explained with reference to Figure 5, the process of releasing the interlock of the indoor unit 50 can be simplified. Consequently, the workload of worker W can be reduced.

[0080] [1-3. Effects, etc.] As described above, the air conditioning system 1 has 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 includes a setting unit 32 that sets whether or not to send an interlock release signal SGU to the indoor unit 50 depending on whether or not predetermined conditions are met, and a transmitting unit 33 that sends the interlock release signal SGU to the indoor unit 50 according to the setting result of the setting unit 32. The indoor unit 50 includes an execution unit 72 that sets the indoor unit 50 to an interlock release state STU that allows air conditioning operation when it receives an interlock release signal SGU from the outdoor unit 10, and to an interlock state STL that prohibits air conditioning operation when it does not receive an interlock release signal SGU from the outdoor unit 10. The setting unit 32 sets the interlock release signal SGU to be untransmitted after the transmitting unit 33 has sent the interlock release signal SGU to the indoor unit 50 for a predetermined period of time PD.

[0081] For example, when installing a new outdoor unit 10 and indoor unit 50, if the setting unit 32 is set to enable the transmission of an interlock release signal SGU to the indoor unit 50, and this state is maintained, then when an additional indoor unit 50 is installed or replaced, the interlock release signal SGU will be transmitted to the indoor unit 50 without the operator W having to perform an interlock release operation. In that case, even if the safety device of the newly installed or replaced indoor unit 50 is not inspected, it may become operational. According to the above configuration, the setting unit 32 sets the transmission unit 33 to disable transmission of the interlock release signal SGU to the indoor unit 50 after it has transmitted the SGU for a predetermined period of time. By setting the predetermined period of time to an appropriate period, safety can be improved when the indoor unit 50 is added or replaced. Furthermore, the setting unit 32 sets whether or not to send the interlock release signal SGU to the indoor unit 50 depending on whether or not predetermined conditions are met. By setting the predetermined conditions to appropriate conditions, the setting unit 32 can properly set whether or not to send the interlock release signal SGU to the indoor unit 50.

[0082] In the above-described air conditioning system 1, the indoor unit 50 is equipped with an indoor unit memory 75 that stores a release flag 77 indicating that it is in the interlock release state STU when it receives an interlock release signal SGU from the outdoor unit 10. The execution unit 72 sets the indoor unit 50 to the interlock release state STU when the release flag 77 is stored in the indoor unit memory 75, and sets the indoor unit 50 to the interlock state STL when the release flag 77 is not stored in the indoor unit memory 75.

[0083] According to this, when the outdoor unit 10 receives an interlock release signal SGU, it stores a release flag 77 indicating that it is in the interlock release state STU. Therefore, if the indoor unit 50 receives the interlock release signal SGU at least once, it can be put into the interlock release state STU. Consequently, the period during which the transmission unit 33 of the outdoor unit 10 transmits the interlock release signal SGU to the indoor unit 50 can be appropriately shortened.

[0084] In the above-described air conditioning system 1, the outdoor unit 10 is connected to a high-voltage switch 18 and includes a socket 22 that switches between an open state TQ and a short-circuit state TS based on user operation, and the predetermined condition includes the fact that the power to the outdoor unit 10 is turned on when the socket 22 is in the short-circuit state TS.

[0085] According to this, the predetermined conditions include the power being turned on to the outdoor unit 10 while the socket 22 is in a short-circuit state TS. Therefore, even when an indoor unit 50 is added or replaced, the worker W must connect the high-voltage switch 18 to the socket 22 and turn on the power to the outdoor unit 10. Thus, safety can be improved when an indoor unit 50 is added or replaced.

[0086] In the above-described air conditioning system 1, the predetermined conditions include the fact that after the power to the outdoor unit 10 is turned on with the socket 22 in an open state TQ, the power to the outdoor unit 10 is turned on again with the socket 22 switched to a short-circuit state TS, and the outdoor unit 10 outputs an alarm when the power to the outdoor unit 10 is turned on with the socket 22 in an open state TQ.

[0087] According to this, the predetermined conditions include the fact that after the power to the outdoor unit 10 is turned on with the socket 22 in an open state TQ, the power to the outdoor unit 10 is turned on again with the socket 22 switched to a short-circuit state TS. Therefore, even when an indoor unit 50 is added or replaced, the worker W must first unplug the high-voltage switch 18 from the socket 22 to turn on the power to the outdoor unit 10, and then plug the high-voltage switch 18 back into the socket 22 to turn on the power to the outdoor unit 10. Thus, safety can be improved when an indoor unit 50 is added or replaced. Furthermore, the outdoor unit 10 outputs an alarm when the power to the outdoor unit 10 is turned on while the socket 22 is in the open state TQ, so the worker W can confirm that the socket 22 is in the open state TQ, that is, that the interlock is active. Therefore, the convenience of the worker W can be improved.

[0088] In the above-described air conditioning system 1, the predetermined conditions include the fact that the re-energization is the first re-energization.

[0089] According to this, the predetermined condition includes the fact that the re-energization is the first re-energization. Therefore, each time the power to the outdoor unit 10 is restored while the socket 22 is switched to a short-circuit state TS, it is possible to suppress the transmission unit 33 of the outdoor unit 10 from sending the interlock release signal SGU to the indoor unit 50. Consequently, the period during which the transmission unit 33 of the outdoor unit 10 transmits the interlock release signal SGU to the indoor unit 50 can be shortened to an appropriate period.

[0090] The control method for the air conditioning system 1 is a control method for the 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 performs a setting step in which it sets whether or not to send an interlock release signal SGU to the indoor unit 50 depending on whether or not predetermined conditions are met, and a transmission step in which it sends the interlock release signal SGU to the indoor unit 50 according to the setting result in the setting step. The indoor unit 50 performs an execution step in which, if it receives the interlock release signal SGU from the outdoor unit 10, it sets itself to an interlock release state STU that allows air conditioning operation of the indoor unit 50, and if it does not receive the interlock release signal SGU from the outdoor unit 10, it sets itself to an interlock state STL that prohibits air conditioning operation of the indoor unit 50. In the setting step, after sending the interlock release signal SGU to the indoor unit 50 for a predetermined period PD in the transmission step, the interlock release signal SGU is set to not transmit.

[0091] According to this, the control method for the air conditioning system 1 produces the same effects as the air conditioning system 1 described above.

[0092] (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.

[0093] Figure 7 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 7, 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.

[0094] 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.

[0095] In the modified configuration shown in Figure 7, 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".

[0096] In the modified configuration shown in Figure 7, 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."

[0097] [2-2. 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 8 shows a modified configuration in which the air conditioning system 1 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 8. Furthermore, the first outdoor unit 10a functions as the master unit, and the second outdoor unit 10b functions as the slave unit. In Figure 8, 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, thus 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 33b. 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] The setting unit 32a of the first outdoor unit 10a sets whether or not to send an interlock release signal SGU to the indoor unit 50 when all of the first condition CD1, second condition CD2, and third condition CD3 are met, similar to the setting unit 32 of the outdoor unit 10 described with reference to Figures 1 and 2. Furthermore, the transmitting unit 33a of the first outdoor unit 10a transmits the interlock release signal SGU to the indoor unit 50 when the setting unit 32a is set to enable the transmission of the interlock release signal SGU to the indoor unit 50, similar to the setting unit 32 of the outdoor unit 10 described with reference to Figures 1 and 2.

[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, the case in which the "predetermined conditions" consist of a first condition CD1, a second condition CD2, and a third condition CD3 was described, but the "predetermined conditions" are not limited to this. The "predetermined conditions" may consist, for example, a first condition CD1 and a second condition CD2. Alternatively, the "predetermined conditions" may consist, for example, a second condition CD2. In this case, the second condition CD2 is that the power to the outdoor unit 10 is turned on when the short-circuit state TS is in effect.

[0105] 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".

[0106] 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.

[0107] 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).

[0108] 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.

[0109] 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.

[0110] 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.

[0111] (Note) Based on the above description of embodiments, the following technologies are disclosed.

[0112] (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 comprises a setting unit that sets whether or not to transmit an interlock release signal to the indoor unit depending on whether or not predetermined conditions are met, and a transmitting unit that transmits the interlock release signal to the indoor unit according to the setting result of the setting unit, and the indoor unit comprises an execution unit that sets the indoor unit to an interlock release state that allows air conditioning operation when it receives the interlock release signal from the outdoor unit, and sets the indoor unit to an interlock state that prohibits air conditioning operation when it does not receive the interlock release signal from the outdoor unit, and the setting unit sets the interlock release signal to be untransmittable after the transmitting unit has transmitted the interlock release signal to the indoor unit for a predetermined period of time.

[0113] With this configuration, the setting unit sets the transmission unit to disable the transmission of the interlock release signal to the indoor unit after the transmission unit has sent the interlock release signal for a predetermined period. By setting the predetermined period to an appropriate period, safety can be improved when indoor units are added or replaced. Furthermore, the setting unit determines whether or not to send an interlock release signal to the indoor unit depending on whether or not predetermined conditions are met. By setting the predetermined conditions to appropriate conditions, the ability to send an interlock release signal to the indoor unit can be properly set.

[0114] (Technology 2) The air conditioning system according to Technical 1, wherein the indoor unit is equipped with an indoor unit memory that stores interlock release information indicating that it is in an interlock release state when it receives the interlock release signal from the outdoor unit, and the execution unit sets the indoor unit to the interlock release state when the interlock release information is stored in the indoor unit memory, and sets the indoor unit to the interlock state when the interlock release information is not stored in the indoor unit memory.

[0115] With this configuration, when an interlock release signal is received from the outdoor unit, interlock release information indicating that the interlock is released is stored. Therefore, the indoor unit can be put into the interlock release state after receiving the interlock release signal at least once. Consequently, the period during which the outdoor unit's transmitter sends the interlock release signal to the indoor unit can be appropriately shortened.

[0116] (Technology 3) The air conditioning system according to Technology 1 or Technology 2, wherein the outdoor unit is equipped with a switching circuit that switches between a first state and a second state different from the first state based on user operation, and the predetermined condition includes the switching circuit being in the second state and the power to the outdoor unit being turned on.

[0117] According to this configuration, the predetermined condition includes the outdoor unit being powered on when the switching circuit is in the second state. Therefore, even when an indoor unit is added or replaced, the operator must switch the switching circuit to the second state and power on the outdoor unit. Consequently, safety can be improved when an indoor unit is added or replaced.

[0118] (Technology 4) The predetermined conditions include the fact that the power to the outdoor unit is turned on when the switching circuit is in the first state, and then the power to the outdoor unit is turned on again when the switching circuit is switched to the second state, and the outdoor unit outputs an alarm when the power to the outdoor unit is turned on when the switching circuit is in the first state, as described in Technical 3.

[0119] According to this configuration, the predetermined conditions include the fact that after the power to the outdoor unit is turned on with the switching circuit in the first state, the power to the outdoor unit is turned on again with the switching circuit switched to the second state. Therefore, even when indoor units are added or replaced, the worker must turn on the power to the outdoor unit with the switching circuit in the first state, then switch the switching circuit to the second state, and then turn on the power to the outdoor unit. Thus, safety can be improved when indoor units are added or replaced. Furthermore, the outdoor unit outputs an alarm when the power to the outdoor unit is turned on while the switching circuit is in the first state, allowing the operator to confirm that the switching circuit is in the first state. Therefore, the convenience of the operator can be improved.

[0120] (Technology 5) The air conditioning system according to Technical Reference 4, wherein the predetermined conditions include the re-energization being the first re-energization.

[0121] According to this configuration, the predetermined condition includes the fact that the re-energization is the first re-energization. Therefore, each time the power to the outdoor unit is restored while the switching circuit is switched to the second state, the transmission unit of the outdoor unit can be prevented from sending an interlock release signal to the indoor unit. Consequently, the period during which the transmission unit of the outdoor unit sends an interlock release signal to the indoor unit can be shortened to an appropriate period.

[0122] (Technology 6) 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, wherein the outdoor unit performs a setting step of setting whether or not to send an interlock release signal to the indoor unit depending on whether or not predetermined conditions are met, and a transmission step of sending the interlock release signal to the indoor unit according to the setting result in the setting step, and the indoor unit performs an execution step of setting the indoor unit to an interlock release state that allows air conditioning operation of the indoor unit when it receives the interlock release signal from the outdoor unit, and setting the indoor unit to an interlock state that prohibits air conditioning operation of the indoor unit when it does not receive the interlock release signal from the outdoor unit, and in the setting step, after sending the interlock release signal to the indoor unit for a predetermined period of time in the transmission step, the method for controlling an air conditioning system.

[0123] This configuration produces the same effect as the air conditioning system of Technology 1. [Industrial applicability]

[0124] This disclosure is applicable to applications that improve safety when indoor units are added or refurbished. [Explanation of Symbols]

[0125] 1. Air conditioning system 10 Outdoor unit 18 High-voltage switch 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 Setting section 33 Transmitter 35 Outdoor unit memory 36 Outdoor Unit Program 37 History Storage Unit 50 Indoor unit 60 Indoor Unit Control Unit 61 Indoor unit communication circuit 70 Indoor Unit Processor 71 Cancellation Request Department 72 Execution Department 75 Indoor unit memory 76 Indoor Unit Program 77 Release Flag (Interlock Release Information) 90 Remote Control CD1 First condition (part of the prescribed conditions) CD2 Second condition (part of the prescribed conditions) CD3 Third condition (part of the prescribed conditions) 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 having an outdoor unit and an indoor unit that are connected to each other in a manner that enables communication between them, The aforementioned outdoor unit is, A setting unit that sets whether or not to send an interlock release signal to the indoor unit depending on whether or not predetermined conditions are met, A transmitting unit transmits the interlock release signal to the indoor unit according to the setting result of the setting unit, Equipped with, The indoor unit includes an execution unit that, when it receives the interlock release signal from the outdoor unit, sets the indoor unit to an interlock release state that allows air conditioning operation, and when it does not receive the interlock release signal from the outdoor unit, sets the indoor unit to an interlock state that prohibits air conditioning operation. The setting unit, after the transmission unit has transmitted the interlock release signal to the indoor unit for a predetermined period of time, sets the transmission of the interlock release signal to disabled. Air conditioning system.

2. The aforementioned indoor unit is The indoor unit is equipped with an indoor unit memory that stores interlock release information indicating that the interlock is released when the interlock release signal is received from the outdoor unit. The execution unit sets the indoor unit to the interlock-released state when the interlock-release information is stored in the indoor unit memory, and sets the indoor unit to the interlocked state when the interlock-release information is not stored in the indoor unit memory. The air conditioning device according to claim 1.

3. The outdoor unit is equipped with a switching circuit that switches between a first state and a second state different from the first state based on user operation. The predetermined conditions include the switching circuit being in the second state and the power to the outdoor unit being turned on. An air conditioning device according to claim 1 or claim 2.

4. The predetermined conditions include the fact that after the power to the outdoor unit is turned on while the switching circuit is in the first state, the power to the outdoor unit is turned on again while the switching circuit is switched to the second state. The outdoor unit outputs an alarm when the power to the outdoor unit is turned on while the switching circuit is in the first state. The air conditioning device according to claim 3.

5. The aforementioned predetermined conditions include the fact that the re-insertion is the first re-insertion. The air conditioning device according to claim 4.

6. 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, The aforementioned outdoor unit is, A setting step that determines whether or not an interlock release signal can be sent to the indoor unit depending on whether or not predetermined conditions are met, A transmission step which transmits the interlock release signal to the indoor unit according to the setting result in the setting step, Execute, The indoor unit performs an execution step in which, upon receiving the interlock release signal from the outdoor unit, it enters an interlock release state that permits the indoor unit to operate its air conditioning system, and, if it does not receive the interlock release signal from the outdoor unit, it enters an interlock state that prohibits the indoor unit to operate its air conditioning system. In the setting step, after transmitting the interlock release signal to the indoor unit for a predetermined period in the transmission step, the transmission of the interlock release signal is disabled. A method for controlling an air conditioning system.

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