Air conditioning system

Abstract

In this invention, a refrigerant sensor device is set with a first concentration threshold value and a second concentration threshold value smaller than the first concentration threshold value and outputs a first signal to a control unit when a concentration detected by a refrigerant sensor is equal to or greater than the first concentration threshold value, and outputs a second signal to the control unit when the concentration is equal to or greater than the second concentration threshold value but smaller than the first concentration threshold value. When the first signal is continuously input, the control unit brings an alarm unit into operation regardless of the operation status of a blower fan. When the second signal is continuously input and the blower fan is in operation, the control unit brings the alarm unit into operation.

Description

air conditioning system

[0001] The present disclosure relates to air conditioning systems.

[0002] Some air conditioning systems include an indoor unit that has a refrigerant sensor capable of detecting the concentration of a refrigerant and controls the rotation speed of a blower fan in accordance with the refrigerant concentration detected by the refrigerant sensor. For example, the air conditioner described in Patent Document 1 has a sensor capable of detecting the concentration of a refrigerant, and if the refrigerant concentration detected by the sensor while the blower fan is operating is equal to or greater than a first predetermined reference value, the air conditioner stops operation of the blower fan and detects a refrigerant leak based on the detection result of the sensor after the blower fan has been stopped.

[0003] International Publication No. 2019 / 077696

[0004] Refrigerant sensors are often installed inside the housing of the indoor unit. They are sometimes installed in a location where air flows due to the rotation of the blower fan. When refrigerant leaks inside the housing, the refrigerant concentration around the refrigerant sensor differs depending on whether the blower fan is rotating or not. When the blower fan is rotating, the leaked refrigerant flows out along with the air around the refrigerant sensor. In this case, the refrigerant concentration around the refrigerant sensor is lower than when the blower fan is stopped.

[0005] When detecting whether a refrigerant leak has occurred, the refrigerant sensor outputs a monitoring pulse signal to the indoor unit's control unit. When the refrigerant sensor detects a concentration equal to or greater than a predetermined concentration threshold, it outputs an alarm pulse signal instead of the monitoring pulse signal. When the control unit receives the alarm pulse signal from the refrigerant sensor, it activates an alarm. When refrigerant leaks into the indoor unit's housing, if the blower fan is rotating, it takes longer for the refrigerant concentration around the refrigerant sensor to reach the concentration threshold than if the blower fan is stopped. This can result in a problem of delayed alarm activation.

[0006] A first aspect of the present disclosure is an air conditioning system comprising an indoor unit, an outdoor unit, a refrigerant circuit in which a refrigerant is sealed, and an alarm that issues an alarm, wherein the indoor unit comprises: a refrigerant sensor device having a refrigerant sensor capable of detecting the concentration of the refrigerant; a housing that houses a part of the refrigerant circuit and the refrigerant sensor device and has an inlet and an outlet; a blower fan that generates an airflow that is drawn in through the inlet and blown out through the outlet; and a control unit that controls operation of the blower fan and the alarm, and wherein the refrigerant sensor device detects a first concentration threshold value and a second concentration threshold value. a first signal is output to the control unit when the concentration detected by the refrigerant sensor is equal to or greater than the first concentration threshold, and a second signal is output to the control unit when the concentration detected by the refrigerant sensor is equal to or greater than the second concentration threshold but less than the first concentration threshold; the control unit activates the alarm when the first signal is continuously input, regardless of the operating status of the blower fan, and activates the alarm when the second signal is continuously input and the blower fan is operating.

[0007] A second aspect of the present disclosure is an air conditioning system comprising an indoor unit, an outdoor unit, a refrigerant circuit in which a refrigerant is sealed, and an alarm that issues an alarm, wherein the indoor unit comprises a first refrigerant sensor device having a first refrigerant sensor capable of detecting the concentration of the refrigerant, a second refrigerant sensor device having a second refrigerant sensor capable of detecting the concentration of the refrigerant, a housing that houses a part of the refrigerant circuit, the first refrigerant sensor device, and the second refrigerant sensor device and has an inlet and an outlet, a blower fan that generates an airflow that is sucked in through the inlet and blown out through the outlet, and a control unit that controls the operation of the blower fan and the alarm, and the first refrigerant sensor device The air conditioning system has a first concentration threshold set, and outputs a first signal to the control unit when the concentration detected by the first refrigerant sensor is equal to or greater than the first concentration threshold; the second refrigerant sensor device has a second concentration threshold set that is smaller than the first concentration threshold, and outputs a second signal to the control unit when the concentration detected by the second refrigerant sensor is equal to or greater than the second concentration threshold; the control unit activates the alarm when the first signal is continuously input, regardless of the operating status of the blower fan; and activates the alarm when the second signal is continuously input and the blower fan is operating when the first signal is not input.

[0008] According to the present disclosure, it is possible to reduce the difference in the time from when a refrigerant leaks inside the housing until an alarm is issued, depending on the operating status of the blower fan.

[0009] FIG. 1 is a diagram illustrating an example of the configuration of an air conditioning system according to embodiment 1. FIG. 2 is a diagram illustrating an example of the configuration of an indoor unit according to embodiment 1. FIG. 3 is a block diagram illustrating an example of the functional configuration of the air conditioning system according to embodiment 1. FIG. 4 is a flowchart illustrating notification processing according to embodiment 1. FIG. 5 is a diagram illustrating an example of an output signal according to embodiment 1. FIG. 6 is a diagram illustrating an example of the schematic configuration of an air conditioning system according to embodiment 1. FIG. 7 is a diagram illustrating an example of a display of a remote control according to embodiment 1. FIG. 8 is a flowchart illustrating notification processing according to embodiment 2. FIG. 9 is a diagram illustrating an example of the hardware configuration of a refrigerant sensor device according to embodiment 1. FIG. 10 is a diagram illustrating an example of the hardware configuration of a refrigerant sensor device according to embodiment 3. FIG. 11 is a diagram illustrating another example of the hardware configuration of a refrigerant sensor device according to embodiment 3. FIG. 12 is a diagram illustrating an example of the hardware configuration of a refrigerant sensor device according to embodiment 4.

[0010] Air conditioning systems and indoor units according to embodiments of the present disclosure will be described below with reference to the drawings. <Embodiment 1> First, embodiment 1 of the present disclosure will be described. FIG. 1 is a diagram showing an example configuration of an air conditioning system 100 according to this embodiment. The air conditioning system 100 includes an outdoor unit 10, an indoor unit 20, a refrigerant sensor device 30, and a remote control 40. As will be described later, the remote control 40 functions as an alarm 60 (FIG. 3). The air conditioning system 100 also includes a refrigerant circuit RC. The refrigerant circuit RC includes refrigerant pipes 50a and 50b and connects the outdoor unit 10 and the indoor unit 20. A refrigerant is sealed in the refrigerant pipes 50a and 50b. The refrigerant circulates in the refrigerant circuit RC.

[0011] The refrigerant circuit RC is connected to a compressor 12, an outdoor heat exchanger 13, a pressure reducing mechanism 14, a four-way valve 16, shut-off valves 18a and 18b, and an indoor heat exchanger 22. The refrigerant may be any flammable refrigerant such as R32 or R454B, which will be described later.

[0012] The outdoor unit 10 can be placed outdoors, i.e., outside the space to be air-conditioned. The outdoor unit 10 is connected to the indoor unit 20 using refrigerant pipes 50a and 50b. The outdoor unit 10 is a heat source machine that generates heat to be supplied to the indoor unit 20. The outdoor unit 10 includes a compressor 12, an outdoor heat exchanger 13, a pressure reducing mechanism 14, a four-way valve 16, shut-off valves 18a and 18b, an outdoor fan 15, and an outdoor unit control device 17.

[0013] The compressor 12 compresses the refrigerant sealed in the refrigerant circuit RC. The output of the compressor 12 is variable. The compressor 12 draws in and compresses the refrigerant, bringing it to a state of higher temperature and pressure than before compression. The refrigerant circulating through the refrigerant circuit RC exchanges heat with outside air in both the outdoor unit 10 and the indoor unit 20.

[0014] The four-way valve 16 is a valve for switching the direction of refrigerant flow, and switches the direction of the refrigerant circulating through the refrigerant circuit RC between heating operation and cooling operation of the air conditioning system 100. In the example shown in Figure 1, the solid line indicates the direction of refrigerant flow in cooling operation, and the dashed line indicates the direction of refrigerant flow in heating operation.

[0015] The outdoor heat exchanger 13 exchanges heat between the outside air and the refrigerant. During cooling operation, the outdoor heat exchanger 13 rejects heat from the refrigerant to the outside air. During heating operation, the outdoor heat exchanger 13 absorbs heat from the outside air into the refrigerant. The outdoor heat exchanger 13 is, for example, a cross-fin type fin-and-tube heat exchanger. A cross-fin type fin-and-tube heat exchanger includes a heat transfer tube and a number of fins.

[0016] The pressure reducing mechanism 14 is disposed on the refrigerant circuit RC and reduces the pressure of the refrigerant to expand it. The outdoor fan 15 is a blower that blows air to the outdoor heat exchanger 13. The outdoor fan 15 is, for example, a propeller fan.

[0017] The shutoff valve 18a is installed on the refrigerant circuit RC between the pressure reducing mechanism 14 and the indoor unit 20. In addition, the shutoff valve 18b is installed on the refrigerant circuit RC between the four-way valve 16 and the indoor unit 20. When the shutoff valves 18a and 18b are closed, the refrigerant circuit RC between the outdoor unit 10 and the indoor unit 20 is shut off, and the movement of refrigerant between the indoor unit 20 and the outdoor unit 10 while the operation is stopped is prevented.

[0018] The outdoor unit control device 17 controls each part of the outdoor unit 10 and is capable of communicating with the indoor unit 20. The outdoor unit control device 17 is configured to include an arithmetic circuit such as a processor, for example. The processor is, for example, a CPU (Central Processing Unit).

[0019] The indoor unit 20 supplies cold or hot heat to a space to be air-conditioned. The space to be air-conditioned is, for example, a room where a user is located. The indoor unit 20 includes an indoor heat exchanger 22, a blower fan 23, and an indoor unit control device 24.

[0020] The indoor heat exchanger 22 exchanges heat between the indoor air and the refrigerant to supply cold or hot heat to the space to be air-conditioned. During heating operation, the indoor heat exchanger 22 dissipates heat from the refrigerant to the indoor air. During cooling operation, the indoor heat exchanger 22 absorbs heat from the indoor air into the refrigerant. The indoor heat exchanger 22 is, for example, a cross-fin type fin-and-tube heat exchanger.

[0021] The blower fan 23 is a blower device that blows air to the indoor heat exchanger 22. The blower fan 23 is, for example, a turbo fan. The indoor unit control device 24 determines the rotation speed of the blower fan 23 based on the voltage supplied to a fan motor that rotates and drives the blower fan 23. For example, a data table or function indicating the relationship between the voltage supplied to the fan motor and the rotation speed is set in advance in the indoor unit control device 24, and the rotation speed is calculated based on the supplied voltage.

[0022] The indoor unit control device 24 controls the operation of the indoor unit 20. The indoor unit control device 24 is an example of a control unit that controls the operation of the refrigerant circuit RC (the operation of the air conditioning system 100). The indoor unit control device 24 is configured to include an arithmetic circuit such as a processor. The processor is, for example, a CPU.

[0023] The indoor unit control device 24 communicates with the outdoor unit control device 17 in accordance with operation instructions (operation commands) from a remote control 40 (described later), and controls the refrigerant circuit RC together with the outdoor unit control device 17 .

[0024] Furthermore, the indoor unit control device 24 executes refrigerant leakage abnormality processing when it receives a pulse signal indicating a refrigerant leakage from the refrigerant sensor device 30, which will be described later. The refrigerant leakage abnormality processing includes processing to output notification information indicating a refrigerant leakage to the alarm device 60 (FIG. 3). An alarm is issued in response to the output of the notification information to the alarm device 60. The refrigerant leakage abnormality processing may also include processing to close the shutoff valves 18a and 18b.

[0025] The refrigerant sensor device 30 detects refrigerant leakage from the refrigerant circuit RC. The refrigerant sensor device 30 is installed inside the housing of the indoor unit 20. As shown in FIG. 9 , the refrigerant sensor device 30 has one refrigerant sensor 31 that detects refrigerant leakage from the refrigerant circuit RC. When the refrigerant sensor device 30 detects a refrigerant leakage, it outputs a pulse signal indicating the detection to the indoor unit control device 24. The detection of refrigerant leakage and the pulse signal will be described later. Note that the refrigerant sensor device 30 may output a monitoring signal indicating that it is monitoring for refrigerant leakage to the indoor unit control device 24 during normal times when no refrigerant leakage is detected.

[0026] The remote control 40 (remote controller) is an external terminal device for controlling the operation of the air conditioning system 100 in response to user operation. The remote control 40 may also function as an alarm device 60 that issues an alarm when the refrigerant sensor 31 detects a refrigerant leak, as illustrated in FIG. 3 . When issuing an alarm, the alarm device 60 flashes or lights up a lamp and also issues a warning sound, as will be described later. This notifies the user that a refrigerant leak has occurred. Details of the remote control 40 will be described later with reference to FIGS. 3 and 7.

[0027] Next, an example configuration of the indoor unit 20 will be described. FIG. 2 is a diagram showing an example configuration of the indoor unit 20 according to this embodiment. The indoor unit 20 illustrated in FIG. 2 is a ceiling-embedded type. The upper part of FIG. 2 shows the interior of the housing of the indoor unit 20. The lower part of FIG. 2 shows the x-x' cross section of the upper part. In FIG. 2, C indicates the ceiling surface surrounding the indoor unit 20. One air inlet 27 is provided in the center of the indoor unit 20. Around the periphery of the air inlet 27, one air outlet 28 is provided along each side of the outer edge of the indoor unit, for a total of four air outlets 28. Each component of the indoor unit 20 is housed inside the housing 21. The blower fan 23 is located approximately in the center inside the indoor unit 20. The indoor heat exchanger 22 is located around the blower fan 23. Refrigerant pipes 50a and 50b (FIG. 1) are connected to the indoor heat exchanger 22. When the blower fan 23 rotates, air is drawn into the housing 21 through the intake port 27 of the indoor unit 20, passes through the indoor heat exchanger 22, and flows out of the housing 21 through the outlet port 28, i.e., into the space to be air-conditioned.

[0028] The airflow generated by the operation of the blower fan 23 passes through the indoor heat exchanger 22. Heat exchange occurs between the air passing through the indoor heat exchanger 22 and the refrigerant flowing inside the indoor heat exchanger 22. Refrigerant flows into the indoor heat exchanger 22 from refrigerant piping 50a, and the refrigerant, whose temperature has been changed by heat exchange, flows out from refrigerant piping 50b. A drain pan 25 is installed below the indoor heat exchanger 22. In the example of FIG. 2 , water droplets adhering to the indoor heat exchanger 22 drip onto the drain pan 25. The refrigerant sensor device 30 is installed near the blower fan 23 inside the housing 21. This location is chosen to emphasize ease of maintenance, such as attachment / detachment and cleaning.

[0029] Assume now that refrigerant leaks from the indoor heat exchanger 22 that constitutes the refrigerant circuit RC. Because refrigerant has a greater specific gravity than the atmosphere, the leaked refrigerant also accumulates on the drain pan 25. The accumulated refrigerant diffuses with the air flow while the blower fan 23 is operating. Therefore, the refrigerant concentration inside the housing 21 tends to be lower than when the blower fan 23 is stopped. In this embodiment, as will be described later, while the blower fan 23 is operating, the presence or absence of refrigerant leakage is determined using a second concentration threshold that is higher than the first concentration threshold when the blower fan 23 is stopped.

[0030] Next, an example of the functional configuration of the air conditioning system 100 according to this embodiment will be described with reference to FIG. 3. FIG. 3 is a block diagram showing an example of the functional configuration of the air conditioning system 100 according to this embodiment. The air conditioning system 100 includes an indoor unit control device 24, a refrigerant sensor device 30, and a remote control 40. The refrigerant sensor device 30 includes a refrigerant sensor 31, a sensor storage unit 32, and a sensor control unit 33. As illustrated in FIG. 9, the refrigerant sensor device 30 is configured by arranging the refrigerant sensor 31 and an integrated circuit IC on a circuit board PB. The integrated circuit IC functions as the sensor storage unit 32 and the sensor control unit 33. The refrigerant sensor device 30 is connected to the indoor unit control device 24 by wire using a communication cable via a connector unit (not shown).

[0031] The refrigerant sensor 31 detects the concentration of refrigerant leaking from the refrigerant circuit RC and notifies the detected concentration to the sensor control unit 33. The refrigerant sensor 31 may be a sensor employing any detection method, such as a semiconductor gas sensor or an NDIR gas sensor.

[0032] The sensor storage unit 32 stores various information used by the sensor control unit 33. The sensor storage unit 32 includes storage media such as random access memory (RAM), read only memory (ROM), and flash memory. The sensor storage unit 32 stores, for example, various setting values ​​in advance. The setting values ​​include the signal pattern of the output signal output to the indoor unit control device 24 and a concentration threshold value used to determine the notification pattern for a refrigerant leak.

[0033] The sensor control unit 33 controls the operation of the refrigerant sensor device 30 independently of the indoor unit control device 24. The sensor control unit 33 is configured to include, for example, an arithmetic circuit such as a processor. The processor is, for example, a CPU. The sensor control unit 33 may be configured to include a microcontroller. The sensor control unit 33 references the setting values ​​stored in the sensor storage unit 32 and determines a notification pattern for a refrigerant leak inside the indoor unit 20 based on the refrigerant concentration input from the refrigerant sensor 31. The sensor control unit 33 generates an output signal related to the determined notification pattern and outputs the generated output signal to the indoor unit control device 24.

[0034] The notification pattern corresponds to the type of output signal and the detected refrigerant concentration range. For example, when the refrigerant concentration is equal to or greater than a first concentration threshold, the sensor control unit 33 determines the notification pattern as Notification 1. The sensor control unit 33 generates a first pulse signal as the output signal related to Notification 1. The sensor control unit 33 outputs the generated first pulse signal (first signal) to the indoor unit control device 24. When the refrigerant concentration is equal to or greater than a second concentration threshold that is smaller than the first concentration threshold but less than the first concentration threshold, the sensor control unit 33 determines the notification pattern as Notification 2. The sensor control unit 33 generates a second pulse signal (second signal) as the output signal related to Notification 2. The sensor control unit 33 outputs the generated second pulse signal to the indoor unit control device 24. In other cases, the sensor control unit 33 may output a monitoring signal indicating that the refrigerant concentration is being monitored to the indoor unit control device 24 as the output signal.

[0035] The first concentration threshold is a threshold for determining whether or not a refrigerant leak has occurred, regardless of the operating status of the blower fan 23, based on whether or not a concentration above that threshold is detected. The second concentration threshold is a threshold for determining whether or not a refrigerant leak has occurred, based on whether or not a concentration above that threshold is detected while the blower fan 23 is operating. The second concentration threshold can be a value smaller than the first concentration threshold. When the refrigerant used is R32, a typical first concentration threshold is, for example, 5000 ppm, and the second concentration threshold is, for example, 3500 ppm. The reference rotation speed is a low rotation speed threshold for determining whether or not the blower fan 23 is operating. The reference rotation speed is, for example, a rotation speed of the blower fan 23 that provides a heat exchange amount significantly different from the heat exchange amount when the blower fan 23 is not operating. A typical reference rotation speed is, for example, 230 rpm.

[0036] Next, an example of an output signal will be described. For example, a PMW (Pulse Width Modulation) signal is used as the output signal. The PMW signal is a binary signal that periodically displays an on period indicating an on state and an off period indicating an off state. The on state and the off state are represented by a high voltage value (H: High) and a low voltage value (L: Low), respectively. The high voltage value is a voltage value significantly higher than the low voltage value. The length of the on period corresponds to the pulse width. The notification pattern of the PWM signal is expressed using a duty ratio. The duty ratio corresponds to the ratio of the on period in one period.

[0037] FIG. 5 illustrates an example of a PWM signal for each row. The period SD of the PWM signal illustrated in FIG. 5 is common to all rows, but the on-period DH varies for each row. FIGS. 5(a), (b), and (c) are used as a supervisory signal, a first pulse signal (first signal), and a second pulse signal (second signal), respectively. In the example of FIG. 5, the period SD is 375 msec. The on-period DH01 of the supervisory signal is 75 msec. The on-period DH02 of the first pulse signal is 150 msec. The on-period DH03 of the second pulse signal is 225 msec.

[0038] Returning to FIG. 3 , an example configuration of the remote control 40 will be described. The remote control 40 includes an external communication unit 41, an input unit 42, a display unit 43, and a remote control control unit 44. The remote control 40 has the functions of an alarm device 60. The functions of the alarm device 60 are realized using the display unit 43 and a part of the remote control control unit 44. The external communication unit 41 is capable of wireless communication with the indoor unit control device 24. The external communication unit 41 transmits operation command information and the like input from the remote control control unit 44 to the indoor unit control device 24. The external communication unit 41 also receives alarms and other notification information from the indoor unit control device 24 and outputs it to the remote control control unit 44. In communication with the indoor unit control device 24, the external communication unit 41 may use communication methods such as infrared communication and short-range wireless communication in addition to wired communication.

[0039] The input unit 42 receives an operation from the user and notifies an operation command corresponding to the received operation to the remote control unit 44. The input unit 42 includes an input device such as an operation button.

[0040] The display unit 43 displays a display screen showing various notification information notified from the remote control unit 44. The display unit 43 displays, for example, the operating status of the air conditioning system 100 on the display screen. If a refrigerant leak is detected in the refrigerant sensor device 30, the display unit 43 issues an alarm indicating the refrigerant leak. The display unit 43 includes, for example, a liquid crystal display. The display constituting the display unit 43 and the touch sensor constituting the input unit 42 may be integrated and configured as a touch panel. The display unit 43 further includes an LED lamp 62 and a speaker 64. The LED lamp 62 and the speaker 64 are used to issue the alarm.

[0041] The remote control control unit 44 executes processing to realize the functions of the remote control 40. The remote control control unit 44 receives various operation commands from the input unit 42, for example, and outputs them to the indoor unit control device 24 using the external communication unit 41. The remote control control unit 44 displays notification information indicating the operation status received from the indoor unit control device 24 using the external communication unit 41 on the display unit 43. When a refrigerant leak is detected, the remote control control unit 44 receives a refrigerant leak alarm from the indoor unit control device 24 using the external communication unit 41. At this time, the remote control control unit 44 causes the display unit 43 to issue a refrigerant leak alarm.

[0042] When issuing an alarm, the remote control unit 44 lights or flashes the LED lamp 62, and outputs an alarm sound signal to the speaker 64 to generate an alarm sound from the speaker 64. At this time, the remote control unit 44 may display a message indicating a refrigerant leak on the LCD display screen, or may flash the backlight of the LCD display. The remote control unit 44 includes, for example, an arithmetic circuit such as a processor. The arithmetic circuit may include, for example, a microcomputer.

[0043] Next, a display example of the remote control 40 will be described. FIG. 7 is a diagram illustrating a display example of the remote control 40. The design surface of the remote control 40 is provided with an LED lamp 62, a speaker 64, and a liquid crystal display representing the display screen G1. The LED lamp 62, the speaker 64, and part of the liquid crystal display implement the function of the alarm device 60. The liquid crystal display occupies most of the design surface of the remote control 40, and the LED lamp 62 and the speaker 64 are arranged on the left and right sides above it, in that order. When an alarm is issued, the LED lamp 62 lights up or flashes periodically, and the speaker 64 emits a warning sound. The warning sound is a buzzer sound having a predetermined signal waveform. When an alarm is not issued, the LED lamp 62 is turned off, and the speaker 64 does not emit a warning sound. When an alarm is not issued, the speaker 64 may be used to present various audio guidance messages.

[0044] The display screen G1 displays a message M1 saying "Refrigerant Leak" and the current time in that order on the first line. The second line displays the operation mode, temperature information, and airflow direction / volume in that order. The message M1 is an example of auxiliary information for the alarm. Note that the message M1 does not necessarily have to be expressed using text, as long as it can communicate the refrigerant leak. If the display unit 43 is configured using a touch panel, the remote control control unit 44 may display guidance information indicating how to deal with the alarm when it detects that the message M1 is pressed. Examples of the ways to deal with the alarm that may be displayed include stopping operation, removing flammable materials, and contacting a service station.

[0045] The message M1 may be expressed using any of graphics, symbols, patterns, etc. instead of or in addition to text. The message M1 may also be expressed to be more noticeable than other types of information, such as the driving mode. For example, the message M1 may be expressed brighter than its surroundings, or may flash.

[0046] Returning to Fig. 3 , an example configuration of the indoor unit control device will be described. The indoor unit control device 24 includes an indoor unit communication unit 241, an indoor unit storage unit 242, and an indoor unit control unit 243. The indoor unit communication unit 241 is capable of communicating with the remote control 40. The indoor unit communication unit 241 is capable of communicating with the outdoor unit control device 17.

[0047] The indoor unit storage unit 242 stores various types of information for controlling the indoor unit 20. The indoor unit storage unit 242 stores in advance various types of notification information, such as the notification pattern of the output signal, the reference rotation speed of the blower fan 23, the duration related to the determination of refrigerant leakage, and an alarm indicating refrigerant leakage.

[0048] The indoor unit control unit 243 executes processing to realize the functions of the indoor unit 20. The indoor unit control unit 243 is configured to include, for example, a processor (not shown). The processor executes a control program to realize the function. In this application, "executing a program" or "executing a program" means executing processing instructed by commands written in the program.

[0049] The indoor unit control unit 243 communicates with the outdoor unit control device 17 using the indoor unit communication unit 241, and controls the operation of the air conditioning system 100 including the refrigerant circuit RC together with the outdoor unit control device 17 based on operation commands received from the remote control 40.

[0050] The indoor unit control unit 243 also monitors the output signal input from the refrigerant sensor device 30. The indoor unit control unit 243 identifies the notification pattern of the output signal by referring to the notification patterns stored in the indoor unit storage unit 242. For example, when the indoor unit control unit 243 determines that the notification pattern of the received output signal is Notification 1, it can determine that the received output signal is a first pulse signal.

[0051] The indoor unit control unit 243 controls the issuance of an alarm based on the notification pattern of the output signal input from the refrigerant sensor device 30 and the operating status of the blower fan 23 input from the indoor unit control device 24. When the indoor unit control unit 243 continuously receives the first pulse signal from the refrigerant sensor device 30 for a period of time equal to or longer than a preset duration, it transmits an alarm indicating a refrigerant leak to the remote control 40 using the indoor unit communication unit 241. This causes the remote control 40 to issue an alarm.

[0052] Furthermore, when the indoor unit control unit 243 continuously receives the second pulse signal from the refrigerant sensor device 30 for a period of time equal to or greater than the duration, it determines whether the rotation speed notified by the blower fan 23 is equal to or greater than the reference rotation speed. If the notified rotation speed is equal to or greater than the reference rotation speed, the indoor unit control unit 243 transmits an alarm indicating a refrigerant leak to the remote control 40 using the indoor unit communication unit 241. The duration is, for example, 5000 ms. The duration associated with receiving the first pulse signal and the duration associated with receiving the second pulse signal may be different. By determining that the first pulse signal or the second pulse signal is continuously input, erroneous determination due to noise contamination or the like is prevented, and more reliable determination is achieved.

[0053] Next, an example of the notification process according to this embodiment will be described. FIG. 4 is a flowchart illustrating the notification process according to this embodiment. (Step S102) The indoor unit control unit 243 monitors the output signal input from the refrigerant sensor device 30. The indoor unit control unit 243 references notification patterns preset in the indoor unit storage unit 242 and identifies the type of notification pattern of the output signal (i.e., sensor input). If the indoor unit control unit 243 cannot identify either notification 1 or 2 (no notification), it repeats the process of step S102. In this case, it is determined that the condition is normal and no refrigerant leakage has occurred.

[0054] When the indoor unit control unit 243 identifies the notification pattern as Notification 1, it proceeds to processing of step S122. At this time, it is communicated to the indoor unit control unit 243 that the refrigerant concentration is equal to or greater than the first concentration threshold. When the indoor unit control unit 243 identifies the notification pattern as Notification 2, it proceeds to processing of step S112. At this time, it is communicated to the indoor unit control unit 243 that the refrigerant concentration is equal to or greater than the second concentration threshold and less than the first concentration threshold.

[0055] (Step S112) The indoor unit control unit 243 determines whether the blower fan 23 is operating (ON) based on the rotation speed notified from the blower fan 23. The indoor control unit 243 can determine whether the blower fan 23 is operating (ON) based on whether the notified rotation speed is equal to or greater than a reference rotation speed. If it is determined that the blower fan 23 is operating (YES), the process proceeds to step S122. If it is determined that the blower fan 23 is not operating (NO), the process returns to step S102.

[0056] (Step S122) The indoor unit control unit 243 generates an alarm by outputting information indicating a refrigerant leak to the remote control 40. Here, the remote control 40, which has the function of the alarm device 60, causes the LED lamp 62 to light up or flash, and generates an alarm sound from the speaker 64. Thereafter, the processing in FIG. 4 ends.

[0057] In the above explanation, an example was given in which the remote control 40 is equipped with the alarm device 60, but the indoor unit 20 main body may also be equipped with the alarm device 60. Furthermore, an alarm device 60 separate from the remote control 40 or the indoor unit 20 may be installed on a wall or the like in the space in which the indoor unit 20 is installed. Note that even when the alarm device 60 is equipped on the indoor unit 20 main body or when it is installed separately from the remote control 40 or the indoor unit 20, when an alarm is issued, the alarm device 60 has the function of turning on or flashing a lamp and emitting a warning sound from a speaker.

[0058] If the indoor unit control unit 243 cannot detect an output signal output from the refrigerant sensor device 30 or cannot identify the notification pattern of the received output signal (for example, whether it is a first pulse signal, a second pulse signal, a monitoring signal, etc.), it may determine that a fault has occurred in the refrigerant sensor device 30. In this case, the indoor unit control unit 243 may send notification information indicating the occurrence of a fault to the alarm.

[0059] As described above, the air conditioning system 100 according to this embodiment includes the indoor unit 20, the outdoor unit 10, a refrigerant circuit RC in which a refrigerant is sealed, and an alarm 60 that issues an alarm. The indoor unit 20 includes a refrigerant sensor device 30, a housing 21, a blower fan 23, and an indoor unit control unit 243. The refrigerant sensor device 30 includes a refrigerant sensor 31 that can detect the concentration of a refrigerant. The housing 21 houses a portion of the refrigerant circuit RC and the refrigerant sensor device 30, and has an inlet 27 and an outlet 28. The blower fan 23 generates a flow of air that is drawn in through the inlet 27 and blown out through the outlet 28. The refrigerant sensor device 30 is set with a first concentration threshold and a second concentration threshold that is smaller than the first concentration threshold, and outputs a first pulse signal (first signal) to the indoor unit control unit 243 when the concentration detected by the refrigerant sensor 31 is equal to or greater than the first concentration threshold, and outputs a second pulse signal (second signal) to the indoor unit control unit 243 when the concentration detected by the refrigerant sensor 31 is equal to or greater than the second concentration threshold but less than the first concentration threshold. When the indoor unit control unit 243 receives a continuous first pulse signal (first signal) from the refrigerant sensor device 30, it activates the alarm 60 regardless of the operating status of the blower fan 23, and when it receives a continuous second pulse signal (second signal) and the blower fan 23 is operating, it activates the alarm 60.

[0060] According to this configuration, the alarm 60 is activated not only when the detected concentration remains equal to or greater than the first concentration threshold regardless of the operating status of the blower fan 23, but also when the detected refrigerant concentration remains equal to or greater than the second concentration threshold and less than the first concentration threshold while the blower fan 23 is operating. Since the alarm is activated even if the detected refrigerant concentration while the blower fan 23 is operating is lower than the concentration when the blower fan 23 is stopped, the problem of a delay in issuing an alarm after a refrigerant leak occurs while the blower fan 23 is operating is solved.

[0061] Next, a second embodiment of the present disclosure will be described. The following description will focus on differences from the first embodiment. The same reference numerals are used for commonalities with the first embodiment, and the same description will be used unless otherwise specified.

[0062] In the air conditioning system 100 according to this embodiment, a third concentration threshold is set in the sensor memory unit 32 of the refrigerant sensor device 30 in addition to the first and second concentration thresholds. The third concentration threshold indicates a concentration lower than the second concentration threshold. The third concentration threshold is, for example, 2500 ppm. In addition to notification 1 and notification 2, notification 3 is set in the sensor memory unit 32 as a notification pattern. Notification 3 is a notification pattern of an output signal that is different from both notification 1 and notification 2.

[0063] The sensor control unit 33 of the refrigerant sensor device 30 determines whether the refrigerant concentration detected by the refrigerant sensor 31 is equal to or greater than the third concentration threshold and less than the second concentration threshold. When it is determined that the refrigerant concentration is equal to or greater than the third concentration threshold and less than the second concentration threshold, the sensor control unit 33 sets the notification pattern to Notification 3. The sensor control unit 33 generates a third pulse signal (third signal) as an output signal related to Notification 3.

[0064] The third pulse signal may be, for example, the PWM signal shown in Figure 5(d). In the example of Figure 5(d), the signal period SD of the third pulse signal is 375 ms, which is equal to the signal period SD of the second pulse signal. In contrast, the on-period DH04 of the third pulse signal is 300 ms, which is longer than the on-period DH03 of the second pulse signal, which is 225 ms. The sensor control unit 33 outputs the generated third pulse signal to the indoor unit control device 24.

[0065] The indoor unit storage unit 242 of the indoor unit control device 24 further stores a notification pattern, "Notification 3," and a reference operating speed as a rotation speed threshold. The reference operating speed is a rotation speed threshold higher than the reference rotation speed according to the first embodiment. That is, the reference operating speed is a threshold for determining whether the blower fan 23 is operating at a higher speed. The reference operating speed is, for example, 680 rpm. The reference operating speed may be equal to or higher than any of the multiple rotation speed levels that can be specified by a user. In contrast, the reference rotation speed according to the first embodiment does not necessarily need to be specified by a user. When the rotation speed (wind speed) can be set to one of four levels, "strong," "medium 2," "medium 1," and "weak," the reference operating speed may be, for example, a rotation speed corresponding to "weak." The reference rotation speed may be a rotation speed corresponding to "gentle breeze." A "gentle breeze" corresponds to a rotation speed lower than "weak."

[0066] In this embodiment, the indoor unit control unit 243 also references the notification patterns stored in the indoor unit storage unit 242 to identify the notification pattern of the output signal. When the indoor unit control unit 243 determines that the notification pattern of the received output signal is Notification 3, it can determine that the received output signal is a third pulse signal. When the indoor unit control unit 243 continuously receives the third pulse signal from the refrigerant sensor device 30 for a period of time equal to or longer than a predetermined duration, it further determines whether the rotation speed notified by the blower fan 23 exceeds the reference operating speed. When the notified rotation speed exceeds the reference operating speed, the indoor unit control unit 243 transmits an alarm indicating a refrigerant leak to the remote control 40 using the indoor unit communication unit 241.

[0067] Next, an example of the notification process according to this embodiment will be described. FIG. 8 is a flowchart illustrating the notification process according to this embodiment. The process of FIG. 8 includes steps S114, S132, and S134 in addition to the process of FIG. 6. In step S102, the indoor unit control unit 243 determines whether the type of notification pattern of the output signal is notification 3, in addition to notifications 1 and 2. If it is determined that the type of notification pattern is notification 3, the process proceeds to step S114. If it is determined in step S112 that the blower fan 23 is operating (ON) (YES), the process proceeds to step S122.

[0068] (Step S114) The indoor unit control unit 243 determines whether the blower fan 23 is operating (ON) based on whether the rotation speed notified from the blower fan 23 is equal to or greater than the reference rotation speed. If it is determined that the blower fan 23 is operating (YES), the process proceeds to step S134. If it is determined that the blower fan 23 is not operating (NO), the process returns to step S102.

[0069] (Step S134) The indoor unit control unit 243 determines whether the operating state of the blower fan 23 is operating at a speed faster than a gentle breeze. In determining whether the operating state is high-speed operation, the indoor unit control unit 243 determines whether the rotation speed of the blower fan 23 exceeds the reference operating speed. If it is determined that the operating state is high-speed operation (YES), the process proceeds to step S122. If it is determined that the operating state is not high-speed operation (NO), the process returns to step S102.

[0070] As described above, in the air conditioning system 100 according to this embodiment, the refrigerant sensor device 30 is further set with a third concentration threshold that is smaller than the second concentration threshold. When the concentration detected by the refrigerant sensor 31 is equal to or greater than the third concentration threshold but less than the second concentration threshold, the refrigerant sensor device 30 outputs a third pulse signal to the indoor unit control unit 243. When the third pulse signal (third signal) is continuously input from the refrigerant sensor device 30 and the blower fan 23 is operating at a rotational speed equal to or greater than a predetermined reference operating speed, the indoor unit control unit 243 activates the alarm 60.

[0071] According to this configuration, the alarm 60 is activated when the detected refrigerant concentration is continuously equal to or greater than the third concentration threshold and less than the second concentration threshold while the blower fan 23 is operating at a rotational speed equal to or greater than the reference operating speed. The alarm is also activated even if the detected refrigerant concentration while the blower fan 23 is operating at a rotational speed equal to or greater than the reference operating speed is lower than the concentration when the blower fan 23 is operating at a lower speed or is stopped. This solves the problem of a delay in issuing an alarm after a refrigerant leak occurs while the blower fan 23 is operating at a high speed.

[0072] Next, a third embodiment of the present disclosure will be described. The following description will mainly focus on differences from the first embodiment. The same reference numerals are used for commonalities with the first embodiment, and the same description will be used unless otherwise specified.

[0073] In the air conditioning system 100 according to this embodiment, the indoor unit 20 is equipped with a first refrigerant sensor device 30-1 and a second refrigerant sensor device 30-2 instead of the refrigerant sensor device 30 (FIG. 2). The first refrigerant sensor device 30-1 and the second refrigerant sensor device 30-2 are housed in a housing 21 (FIG. 3) adjacent to each other within a predetermined range.

[0074] As illustrated in Figure 10, the first refrigerant sensor device 30-1 is configured by arranging a first refrigerant sensor 31-1 and an integrated circuit IC-1 on a substrate PB-1. The integrated circuit IC-1 functions as a first sensor memory unit 32-1 and a first sensor control unit 33-1. The second refrigerant sensor device 30-2 is configured by arranging a second refrigerant sensor 31-2 and an integrated circuit IC-2 on a substrate PB-2. The integrated circuit IC-2 functions as a second sensor memory unit 32-2 and a second sensor control unit 33-2. The first sensor memory unit 32-1 and the second sensor memory unit 32-2 each have the same functions as the sensor memory unit 32. The first sensor control unit 33-1 and the second sensor control unit 33-2 each have the same functions as the sensor control unit 33.

[0075] However, the first refrigerant sensor device 30-1 is configured to have a first concentration threshold and notification 1 as the notification pattern. When the concentration detected by the first refrigerant sensor 31-1 is equal to or greater than the first concentration threshold, the first refrigerant sensor device 30-1 outputs a first pulse signal (first signal) to the indoor unit control unit 243 as the output signal related to notification 1. The second refrigerant sensor device 30-2 is configured to have a second concentration threshold and notification 2 as the notification pattern. When the concentration detected by the second refrigerant sensor 31-2 is equal to or greater than a second concentration threshold that is smaller than the first concentration threshold, the second refrigerant sensor device 30-2 outputs a second pulse signal (second signal) different from the first pulse signal to the indoor unit control unit 243 as the output signal related to notification 2. As shown in Figures 5(b) and 5(c), the first pulse signal and the second pulse signal have the same PWM signal period SD but different on-periods DH.

[0076] The indoor unit control unit 243 executes the process of Fig. 4. However, in step S102, instead of the output signal input from the refrigerant sensor device 30, the indoor unit control unit 243 monitors the output signals input from the refrigerant sensor devices 30-1 and 30-2, and identifies the type of notification pattern of the input output signal.

[0077] As described above, the air conditioning system 100 according to this embodiment includes the indoor unit 20, the outdoor unit 10, a refrigerant circuit RC in which a refrigerant is sealed, and an alarm 60 that issues an alarm. The indoor unit 20 includes a first refrigerant sensor device 30-1, a second refrigerant sensor device 30-2, a housing 21, a blower fan 23, and an indoor unit control unit 243. The first refrigerant sensor device 30-1 includes a first refrigerant sensor 31-1 capable of detecting the concentration of a refrigerant. The second refrigerant sensor device 30-2 includes a second refrigerant sensor 31-2 capable of detecting the concentration of a refrigerant. The housing 21 houses a portion of the refrigerant circuit RC and the refrigerant sensor device 30, and has an inlet 27 and an outlet 28. The blower fan 23 blows air that is drawn in through the inlet 27 and blown out through the outlet 28. A first concentration threshold is set in the first refrigerant sensor device 30-1, and when the concentration detected by the first refrigerant sensor 31-1 is equal to or greater than the first concentration threshold, the first refrigerant sensor device 30-1 outputs a first pulse signal (first signal) to the indoor unit control unit 243. A second concentration threshold lower than the first concentration threshold is set in the second refrigerant sensor device 30-2, and when the concentration detected by the second refrigerant sensor 31-2 is equal to or greater than the second concentration threshold, the second refrigerant sensor device 30-2 outputs a second pulse signal (second signal) to the indoor unit control unit 243. When the first pulse signal is continuously input from the first refrigerant sensor device 30-1, the indoor unit control unit 243 activates the alarm 60 regardless of the operating status of the blower fan 23. When the first pulse signal is not input from the first refrigerant sensor device 30-1, the indoor unit control unit 243 activates the alarm 60 when the second pulse signal is continuously input from the second refrigerant sensor device 30-2 and the blower fan 23 is operating. When the indoor unit control unit 243 receives a continuous first pulse signal from the first refrigerant sensor device 30-1 and a continuous second pulse signal from the second refrigerant sensor device 30-2, it activates the alarm 60 regardless of the operating status of the blower fan 23.

[0078] With this configuration, the alarm 60 is activated not only when the detected refrigerant concentration remains above the first concentration threshold regardless of the operating status of the blower fan 23, but also when the detected refrigerant concentration remains above a second concentration threshold, which is lower than the first concentration threshold, but is less than the first concentration threshold while the blower fan 23 is operating. Since an alarm is issued even when the detected refrigerant concentration is lower while the blower fan 23 is operating than when the blower fan 23 is stopped, the problem of delayed alarm issuance from the point at which a refrigerant leak occurs while the blower fan 23 is operating is solved. Furthermore, by using the first refrigerant sensor device 30-1 and the second refrigerant sensor device 30-2 with different concentration detection thresholds, the process of determining the level to which each detected concentration belongs can be omitted, and the process of outputting different pulse signals depending on the concentration is not required. As shown in FIG. 11 , the first refrigerant sensor 31-1 and the second refrigerant sensor 31-2 may be arranged on the same substrate PB. In this case, the concentrations detected by the first refrigerant sensor 31-1 and the second refrigerant sensor 31-2 may be handled by a single common integrated circuit IC.

[0079] Next, a fourth embodiment of the present disclosure will be described. The following description will mainly focus on differences from the third embodiment. The same reference numerals are used for commonalities with the third embodiment, and the same description will be used unless otherwise specified.

[0080] In the air conditioning system 100 according to this embodiment, the indoor unit 20 further includes a third refrigerant sensor device 30-3 in addition to the first refrigerant sensor device 30-1 and the second refrigerant sensor device 30-2. The third refrigerant sensor device 30-3 is also housed in a housing (FIG. 3). As illustrated in FIG. 12, the first refrigerant sensor device 30-1, the second refrigerant sensor device 30-2, and the third refrigerant sensor device 30-3 are arranged close to one another within a predetermined range. The third refrigerant sensor device 30-3 is configured by arranging a third refrigerant sensor 31-3 and an integrated circuit IC-3 on a substrate PB-3. The integrated circuit IC-3 functions as a third sensor memory unit 32-3 and a third sensor control unit 33-3.

[0081] The third refrigerant sensor device 30-3 is set with a third concentration threshold and a notification pattern of Notification 3. When the concentration detected by the third refrigerant sensor 31-3 is equal to or greater than the third concentration threshold, the third refrigerant sensor device 30-3 outputs a third pulse signal (third signal) to the indoor unit control unit 243 as an output signal related to Notification 3.

[0082] The indoor unit control unit 243 executes the process of Fig. 8. However, in step S102, instead of the output signal input from the refrigerant sensor device 30, the indoor unit control unit 243 monitors the output signals input from the refrigerant sensor devices 30-1, 30-2, and 30-3, and identifies the type of notification pattern of the input output signal.

[0083] As described above, in the air conditioning system 100 according to this embodiment, the indoor unit 20 further includes a third refrigerant sensor device 30-3. The third refrigerant sensor device 30-3 is housed in the housing 21 and includes a third refrigerant sensor 31-3 capable of detecting the refrigerant concentration. A third concentration threshold value lower than the second concentration threshold value is set for the third refrigerant sensor device 30-3. When the concentration detected by the third refrigerant sensor 31-3 is equal to or greater than the third concentration threshold value, the third refrigerant sensor device 30-3 outputs a third pulse signal (third signal) to the indoor unit control unit 243. When the first pulse signal is not input from the first refrigerant sensor device 30-1 and the second pulse signal is not input from the second refrigerant sensor device 30-2, the indoor unit control unit 243 activates the alarm 60 when the third pulse signal is continuously input from the third refrigerant sensor device 30-3 and the blower fan 23 is operating at a rotational speed equal to or greater than a predetermined reference operating speed. When the indoor unit control unit 243 receives a continuous first pulse signal from the first refrigerant sensor device 30-1, a continuous second pulse signal from the second refrigerant sensor device 30-2, and a continuous third pulse signal from the third refrigerant sensor device 30-3, it activates the alarm 60 regardless of the operating status of the blower fan 23. When the indoor unit control unit 243 receives a continuous second pulse signal from the second refrigerant sensor device 30-2 and a continuous third pulse signal from the third refrigerant sensor device 30-3 in a situation where the first pulse signal is not received from the first refrigerant sensor device 30-1, and the blower fan 23 is operating, it activates the alarm 60.

[0084] According to this configuration, the alarm 60 is activated even if the detected refrigerant concentration is continuously equal to or greater than the third concentration threshold and less than the second concentration threshold while the blower fan 23 is operating at a rotational speed equal to or greater than the reference operating speed. An alarm is also issued even if the detected refrigerant concentration while the blower fan 23 is operating at a rotational speed equal to or greater than the reference operating speed is lower than the concentration when the blower fan 23 is operating at a lower speed or is stopped. This solves the problem of a delay in issuing an alarm after a refrigerant leak occurs while the blower fan 23 is operating at a high speed.

[0085] Although the first and third embodiments have two refrigerant concentration thresholds and the second and fourth embodiments have three refrigerant concentration thresholds, the present invention is not limited to this. The number of refrigerant concentration thresholds may be four or more. That is, the refrigerant sensor device 30 and the indoor unit control unit 243 may further be set with a fourth concentration threshold, a fifth concentration threshold, etc. The third concentration threshold, the fourth concentration threshold, the fifth concentration threshold, etc. are thresholds of decreasing concentration in that order. A refrigerant sensor device 30 set with the fourth concentration threshold outputs a fourth pulse signal (fourth signal) to the indoor unit control unit 243 when the concentration detected by the refrigerant sensor 31 is equal to or greater than the fourth concentration threshold. A refrigerant sensor device 30 set with the fifth concentration threshold outputs a fifth pulse signal (fifth signal) to the indoor unit control unit 243 when the concentration detected by the refrigerant sensor 31 is equal to or greater than the fifth concentration threshold.

[0086] In the air conditioning system 100, instead of setting a fourth concentration threshold, a fifth concentration threshold, etc. in the refrigerant sensor device 30, a fourth refrigerant sensor device 30-4, a fifth refrigerant sensor device 30-5, etc. may be provided. The fourth refrigerant sensor device 30-4 includes a fourth refrigerant sensor 31-4 and outputs a fourth pulse signal (fourth signal) to the indoor unit control unit 243 when the detected concentration is equal to or greater than the fourth concentration threshold. The fifth refrigerant sensor device 30-5 includes a fifth refrigerant sensor 31-5 and outputs a fifth pulse signal (fifth signal) to the indoor unit control unit 243 when the detected concentration is equal to or greater than the fifth concentration threshold. Note that the refrigerant sensor device 30 or the sixth refrigerant sensor device 30-6, etc., in which a sixth concentration threshold, etc., is set, may also have the function of outputting a sixth pulse signal (sixth signal) when the detected concentration is equal to or greater than the sixth concentration threshold.

[0087] In addition to the above-mentioned reference operating speed (hereinafter sometimes referred to as the "first reference operating speed"), the indoor unit control unit 243 is configured to set a second reference operating speed, a third reference operating speed, etc. in association with the fourth concentration threshold, the fifth concentration threshold, etc. The first reference operating speed, the second reference operating speed, the third reference operating speed, etc. are thresholds for rotation speeds that increase in order.

[0088] The indoor unit control unit 243 in which the fourth concentration threshold and the second standard operating speed are set activates the alarm 60 when the fourth pulse signal is continuously input and the blower fan 23 is operating at a rotation speed equal to or higher than the second standard operating speed. The indoor unit control unit 243 in which the fifth concentration threshold and the third standard operating speed are set activates the alarm 60 when the fifth pulse signal is continuously input and the blower fan 23 is operating at a rotation speed equal to or higher than the third standard operating speed. The indoor unit control unit 243 in which the sixth concentration threshold, etc. and the fourth standard operating speed, etc. are set may also have the function of activating the alarm 60 when the sixth pulse signal, etc. are continuously input and the blower fan 23 is operating at a rotation speed equal to or higher than the fourth standard operating speed, etc.

[0089] The alarm device 60 may be configured to issue different alarms according to the notification pattern corresponding to the rotation speed of the blower fan 23. For this purpose, different alarms are stored in the indoor unit storage unit 242 for each notification pattern of the output signal. The indoor unit control unit 243 selects an alarm corresponding to the notification pattern identified from the received output signal, and notifies the alarm device 60 of the selected alarm. The alarm device 60 issues the alarm notified by the indoor unit control unit 243.

[0090] For example, the indoor unit control unit 243 selects Alarm 1 in response to continuously receiving a first pulse signal when the refrigerant concentration is equal to or greater than a first concentration threshold, and causes the alarm device 60 to issue the selected Alarm 1. The indoor unit control unit 243 selects Alarm 2 in response to continuously receiving a second pulse signal when the refrigerant concentration is equal to or greater than a second concentration threshold but less than the first concentration threshold, and the blower fan 23 is operating, and causes the alarm device 60 to issue the selected Alarm 2. The indoor unit control unit 243 selects Alarm 3 in response to continuously receiving a third pulse signal when the refrigerant concentration is equal to or greater than a third concentration threshold but less than the second concentration threshold, and the blower fan 23 is operating at a rotational speed equal to or greater than the reference operating speed, and causes the alarm device 60 to issue the selected Alarm 3.

[0091] The visually recognizable element information of the alarm may be represented by different figures, symbols or patterns depending on the type of alarm, or different content may be expressed in text depending on the type. The sound element information of the alarm may be represented by different tones or rhythms depending on the type of alarm, or different content may be expressed in spoken voice depending on the type of alarm.

[0092] In the explanation so far, the first signal, second signal, and third signal have been described as pulse signals transmitted via pulse communication, i.e., the first pulse signal, second pulse signal, and third pulse signal, respectively. However, the communication method between the indoor unit control unit 243 and the refrigerant sensor device 30, and the communication method between the indoor unit control unit 243 and the first refrigerant sensor device 30-1, second refrigerant sensor device 30-2, and third refrigerant sensor device 30-3 are not necessarily limited to pulse communication and may be, for example, UART communication, I2C communication, or wireless communication. When such a communication method is used, the first signal, second signal, and third signal may be signals compatible with that communication method.

[0093] Although the embodiments of the present disclosure have been described above, the present disclosure is not limited to these embodiments and their variations. Addition, omission, substitution, and other modifications of the configuration are possible without departing from the spirit of the present disclosure. The direction of arrows shown in block diagrams and other drawings is for the convenience of explanation and does not limit the direction of the flow of information, data, signals, etc. during implementation. Furthermore, the present disclosure is not limited by the above description, but is limited only by the appended claims.

[0094] According to the indoor unit 20 and air conditioning system 100 of the present disclosure, it is possible to reduce the difference in the time from when refrigerant leaks inside the housing until an alarm is issued, depending on the operating status of the blower fan.

[0095] 10... outdoor unit, 12... compressor, 13... outdoor heat exchanger, 14... pressure reducing mechanism, 15... outdoor fan, 16... four-way valve, 17... outdoor unit control device, 18a, 18b... shut-off valve, 20... indoor unit, 21... housing, 22... indoor heat exchanger, 23... blower fan, 24... indoor unit control device, 27... intake port, 28... outlet port, 30, 30-1, 30-2, 30-3... refrigerant sensor device, 31, 31-1, 31-2, 31-3... refrigerant sensor, 32... sensor sensor memory unit, 33...sensor control unit, 34, 34A, 34B, 34C...connector unit, 40...remote control unit, 41...external communication unit, 42...input unit, 43...display unit, 44...remote control unit, 50a, 50b...refrigerant piping, 60...alarm device, 62...LED lamp, 64...speaker, 100...air conditioning system, 241...indoor unit communication unit, 242...indoor unit memory unit, 243...indoor unit control unit, PB...board, SI...integrated circuit, RC...refrigerant circuit

Claims

1. An air conditioning system comprising an indoor unit, an outdoor unit, a refrigerant circuit in which a refrigerant is sealed, and an alarm that issues an alarm, wherein the indoor unit comprises: a refrigerant sensor device equipped with a refrigerant sensor capable of detecting the concentration of the refrigerant; a housing that houses a part of the refrigerant circuit and the refrigerant sensor device and has an inlet and an outlet; a blower fan that generates an airflow that is drawn in through the inlet and blown out through the outlet; and a control unit that controls the operation of the blower fan and the alarm, wherein the refrigerant sensor device is set with a first concentration threshold detected by the refrigerant sensor and a second concentration threshold that is smaller than the first concentration threshold, and outputs a first signal to the control unit when the concentration detected by the refrigerant sensor is equal to or greater than the first concentration threshold, and outputs a second signal to the control unit when the concentration detected by the refrigerant sensor is equal to or greater than the second concentration threshold but less than the first concentration threshold, and the control unit activates the alarm when the first signal is continuously input, regardless of the operating status of the blower fan, The air conditioning system activates the alarm when the second signal is continuously input and the blower fan is in operation.

2. The air conditioning system of claim 1, wherein the refrigerant sensor device is further configured to set a third concentration threshold value that is smaller than the second concentration threshold value, and outputs a third signal to the control unit when the concentration detected by the refrigerant sensor is equal to or greater than the third concentration threshold value but less than the second concentration threshold value, and the control unit activates the alarm when the third signal is continuously input and the blower fan is operating at a rotational speed equal to or greater than a predetermined standard operating speed.

3. An air conditioning system comprising an indoor unit, an outdoor unit, a refrigerant circuit in which a refrigerant is sealed, and an alarm that issues an alarm, wherein the indoor unit comprises: a first refrigerant sensor device having a first refrigerant sensor capable of detecting the concentration of the refrigerant; a second refrigerant sensor device having a second refrigerant sensor capable of detecting the concentration of the refrigerant; a housing that houses a part of the refrigerant circuit, the first refrigerant sensor device, and the second refrigerant sensor device and has an intake port and an outlet port; a blower fan that generates an airflow that is drawn in through the intake port and blown out through the outlet port; and a control unit that controls the operation of the blower fan and the alarm, wherein the first refrigerant sensor device has a first concentration threshold set, and outputs a first signal to the control unit when the concentration detected by the first refrigerant sensor is equal to or greater than the first concentration threshold, and the second refrigerant sensor device has a second concentration threshold set that is smaller than the first concentration threshold, and outputs a second signal to the control unit when the concentration detected by the second refrigerant sensor is equal to or greater than the second concentration threshold, and the control unit An air conditioning system that activates the alarm when the first signal is continuously input, regardless of the operating status of the blower fan, and that activates the alarm when the second signal is continuously input and the blower fan is operating when the first signal is not input.

4. The air conditioning system of claim 3, wherein the indoor unit further comprises a third refrigerant sensor device having a third refrigerant sensor capable of detecting the concentration of the refrigerant, the third refrigerant sensor device is housed in the housing, the third refrigerant sensor device is set with a third concentration threshold that is smaller than the second concentration threshold, and when the concentration detected by the third refrigerant sensor is equal to or greater than the third concentration threshold but less than the second concentration threshold, the third signal is output to the control unit, and the control unit activates the alarm when the third signal is continuously input in a situation where the first signal and the second signal are not input and the blower fan is operating at a rotational speed equal to or greater than a predetermined standard operating speed.

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