Refrigerant sensor unit

Abstract

A refrigerant sensor unit comprising: a housing accommodating a refrigerant sensor configured to detect a refrigerant leak, the housing accommodating: a connecting part to which a first power supply system and a second power supply system are connected; a first power supply unit configured to supply the current provided by the first power supply system or the second power supply system to the refrigerant sensor; and a switch selectively connecting either the first power supply system or the second power supply system to the first power supply unit.

Description

Technical field The present disclosure relates to a refrigerant sensor unit. State of the art Patent literature 1 discloses a refrigerant sensor unit capable of suppressing the occurrence of a refrigerant sensor malfunction. The refrigerant sensor unit comprises a housing mounted on a wall surface of an interior space, which is an air-conditioned room of an air conditioning system, and a refrigerant sensor housed within the housing. A first side wall, forming a wall surface of the housing, is provided with a first opening that allows a connection between the interior and exterior of the housing. The first opening is located adjacent to, but not facing, the refrigerant sensor. Bibliography Patent literature Patent literature 1: Unexamined Japanese patent publication no. 2022-129916 A Summary of the invention Technical problem The present disclosure relates to a refrigerant sensor unit that is capable of easily switching between multiple connectable power supply systems. Solution A refrigerant sensor unit according to the present disclosure comprises a housing that accommodates a refrigerant sensor which detects a leakage of refrigerant. The housing contains a connection section to which a first power supply system and a second power supply system are connected, a first power supply section that supplies the current provided by the first power supply system or the second power supply system to the refrigerant sensor, and a power supply switching switch that selectively connects either the first power supply system or the second power supply system to the first power supply section. Advantages of the invention In the present disclosure, it is possible to easily switch between multiple connectable power supply systems. Brief description of the drawings [Fig. 1] Fig. 1 is a diagram illustrating a configuration of an air conditioner according to a first embodiment of the present disclosure. [Fig. 2] Fig. 2 is a diagram illustrating a setup of the air conditioner. [Fig. 3] Fig. 3 is a diagram illustrating a configuration of a control system for an indoor unit. [Fig. 4] Fig. 4 is a diagram illustrating a configuration of a control system for a remote control. [Fig. 5] Fig. 5 is a diagram illustrating a configuration of a control system for a refrigerant sensor unit. [Fig. 6] Fig. 6 is a perspective view of the refrigerant sensor unit. [Fig. 7] Fig. 7 shows a rear view of the refrigerant sensor unit. [Fig. 8] Fig. 8 is a flowchart illustrating the operation of the refrigerant sensor unit. [Fig. 9] Fig.Figure 9 is a diagram illustrating a configuration of a refrigerant leak detection system according to a second embodiment of the present disclosure. Description of the embodiments When the inventors arrived at the present disclosure, a refrigerant sensor unit already existed that enables a refrigerant sensor to detect refrigerant escaping into an interior space. Some of these refrigerant sensor units are connected to an indoor air conditioner unit via wiring, so the sensor is powered by the indoor unit. If such a sensor unit is located in a room where the indoor unit is not installed, or if the amount of power supplied by the indoor unit is low, the sensor may need to be powered by a separate power supply system. However, the inventors have found that with conventional refrigerant sensor units, depending on the type of power supply system to be connected, it can be difficult to supply the refrigerant sensor with electrical energy. The inventors have configured the subject matter of the present disclosure in such a way as to solve this problem. Therefore, the present disclosure provides a refrigerant sensor unit that enables easy maintenance. The following sections describe embodiments in detail with reference to the drawings. However, unnecessarily detailed descriptions may be omitted. For example, detailed descriptions of known facts or redundant descriptions of essentially identical configurations may be left out. This is to avoid unnecessary redundancy in the following description and to facilitate understanding for those skilled in the field. The accompanying drawings and the following description are intended to enable those skilled in the art to fully understand the present disclosure and are not intended to limit the subject matter described in the claims. The following sections describe embodiments in detail with reference to the drawings. However, unnecessarily detailed descriptions can be omitted. For example, detailed descriptions of known facts or redundant descriptions of essentially identical configurations can be left out. This serves to avoid unnecessary redundancy in the following description and to facilitate understanding for those skilled in the art. The accompanying drawings and the following description are intended to enable those skilled in the art to fully understand the present disclosure and are not intended to limit the subject matter described in the claims. (First embodiment) A first embodiment is described below with reference to Figures 1, 2, 3, 4, 5, 6, 7 to 8. In each of the drawings, the reference numeral FR denotes a front face of a refrigerant sensor unit 10 in its installed state, the reference numeral UP denotes a top face of the refrigerant sensor unit 10 in its installed state, and the reference numeral LH denotes a left side of the refrigerant sensor unit 10 in its installed state. In the following description, each direction is a direction along the longitudinal axis of the refrigerant sensor unit 10. [1-1. Structure] [1-1-1. Air conditioning system setup] Fig. 1 is a diagram illustrating a configuration of an air conditioning system 1 according to the first embodiment. As shown in Fig. 1, the air conditioning system 1 according to the first embodiment comprises a refrigeration circuit 9 in which a heat exchanger housed in an indoor unit 5, a decompression device housed in an outdoor unit 3 (such as a compressor or an electronic expansion valve), an outdoor heat exchanger contained in the outdoor unit 3, and the like are connected to one another via refrigerant lines 8. In the air conditioning system 1, an interior space 100, which is a room to be air-conditioned, is conditioned by circulating refrigerant through the refrigeration circuit 9. The interior space 100 is a room used by one person. Fig. 2 is a diagram illustrating a configuration of the air conditioning system 1. As shown in Fig. 2, a wall surface 101 of an interior space 100 is provided with an air outlet 6 of the indoor unit 5. The air conditioned by the air conditioning unit 1 in the interior space 100 is blown out of the air outlet 6. The air conditioning unit 1 includes a remote control 7, which functions as the control unit of the air conditioning unit 1. The remote control 7 of the present embodiment is attached to the wall surface 101 of the interior space 100. In the first embodiment, the refrigerant used in the air conditioning system 1, including the indoor unit 5, is, for example, a highly flammable or flammable refrigerant such as R410A or a refrigerant mixture containing R32. If a highly flammable or flammable refrigerant leaks, it is necessary to reduce the amount of refrigerant escaping so that the refrigerant concentration in the indoor unit 100 does not reach the lower flammability limit (LEL). In particular, it is desirable to reduce the amount of refrigerant escaping from the indoor unit 5 installed in the indoor unit 100, another room connected to the indoor unit 100, or the like. The refrigerants used in air conditioning system 1 are gases with a specific gravity that is greater than that of air. A refrigerant sensor unit 10 is located in the interior 100. If refrigerant is detected in the interior 100 at a concentration equal to or exceeding a predetermined value, the refrigerant sensor unit 10 emits a warning tone to inform a person in the interior 100 of the refrigerant leak. The refrigerant sensor unit 10 of the first embodiment is a refrigerant leak detection unit that is included in the air conditioning system 1. [1-1-2. Indoor unit setup] Fig. 3 is a diagram illustrating a configuration of a control system of the indoor unit 5. As shown in Fig. 3, the indoor unit 5 comprises an indoor unit control part 200, a first indoor unit communication part 201 and a second indoor unit communication part 202. The first communication part 201 of the indoor unit comprises communication hardware that conforms to a predetermined communication standard, such as a communication circuit, and communicates with the outdoor unit 3 under the control of the control part 200. In the present embodiment, the indoor unit 5 communicates with the outdoor unit 3 via a communication line CL. The second communication unit 202 of the indoor unit comprises communication hardware that conforms to a predetermined communication standard, such as a communication circuit, and communicates under the control of the control unit 200 of the indoor unit with any device connected to the indoor unit 5 via a remote control cable RL, which constitutes a communication line. The remote control cable RL is a communication line. The second indoor communication unit 202 of the indoor unit 5 communicates with the remote control 7 and the refrigerant sensor unit 10. In the present embodiment, an excitation voltage for controlling the refrigerant sensor unit 10 is applied from the indoor unit 5 to the remote control 7 and the refrigerant sensor unit 10 via the remote control cable RL. In other words, the electrical energy required for operation is supplied from the indoor unit 5 to the remote control 7 and the refrigerant sensor unit 10 via the remote control cable RL. In the first embodiment, the electrical energy supplied by the indoor unit 5 to the refrigerant sensor unit 10 via the cable of the remote control RL is referred to as the first power supply system. The control unit of the indoor unit 200 comprises a processor 210, such as a central processing unit (CPU) or a microprocessor unit (MPU), a memory 220, and an interface circuit for connecting other devices and sensors. Although not shown, various devices contained in the indoor unit 5, such as a temperature sensor, are connected to the interface circuit contained in the control unit 200 of the indoor unit. Memory 220 is a storage device that stores programs and data. Memory 220 stores a control program 221 and data to be processed by processor 210. Memory 220 has a non-volatile memory area. Memory 220 includes a volatile memory area and forms a working area for processor 210. Memory 220 includes, for example, read-only memory (ROM) and random-access memory (RAM). The control unit 200 of the indoor unit controls each unit of the indoor unit 5 and performs various operations by causing the processor 210 to read and execute the control program 221 stored in memory 220. The control unit 200 of the indoor unit controls the operation of the indoor unit 5 by controlling mechanisms related to air conditioning, such as an indoor fan and an indoor expansion valve contained in the indoor unit 5. When the control unit of the indoor unit 200 receives information from the refrigerant sensor unit 10 indicating that a refrigerant leak has occurred, the control unit of the indoor unit 200 transmits the information indicating that a refrigerant leak has occurred to the remote control 7 and the outdoor unit 3. [1-1-3. Remote control setup] Next, the configuration of the remote control 7's control system will be described. Fig. 4 is a diagram illustrating a configuration of a control system of the remote control 7. As shown in Fig. 4, the remote control 7 comprises a remote control control part 300, a remote control communication part 301, a remote control display part 302 and a remote control operating part 303. The communication part of the remote control 301 includes communication hardware that conforms to a predetermined communication standard, such as a communication circuit, and communicates with the indoor unit 5 connected via the remote control cable RL under the control of the control part of the remote control 300. The display part of the remote control 302 includes an LED and a display and, under the control of the control part of the remote control 300, displays various types of information on the LED and the display. The remote control operating unit 303 comprises a variety of control buttons for receiving different commands from a user. The remote control sends a signal corresponding to the pressed control button to the control unit 300 of the remote control. The control unit for the remote control 300 includes a processor 310, such as a CPU or an MPU, a memory 320 and an interface circuit for connecting other devices and sensors. Memory 320 is a storage device that stores programs and data. Memory 320 stores a control program 321 and data to be processed by processor 310. Memory 320 has a non-volatile memory area. Memory 320 also includes a volatile memory area and forms a working area for processor 310. Memory 320 includes, for example, ROM and RAM. The control unit for the remote control 300 controls every part of the remote control 7 and performs various operations by reading and executing the control program 321 stored in memory 320. Although details will be described later, the remote control unit 300 communicates with the indoor unit 5 via the remote control communication unit 301. Furthermore, the remote control unit 300 displays various types of information using the remote control display unit 302. The remote control unit 300 receives various commands from the user based on a signal issued by the remote control unit 303. [1-1-4. Structure of the control system of the refrigerant sensor unit] Fig. 5 is a diagram illustrating a configuration of a control system for the refrigerant sensor unit 10. As shown in Fig. 5, the refrigerant sensor unit 10 comprises a unit control part 400, a unit communication part 401, a buzzer 74, a light element 76 and a refrigerant sensor 92. The unit communication part 401 comprises communication hardware that conforms to a predetermined communication standard, such as a communication circuit, and communicates under the control of the control part 400 with the indoor unit 5, which is connected via the cable of the remote control RL. The buzzer 74 and the light element 76, under the control of the control unit 400, issue an alarm by emitting light or sounding. The buzzer device 74 and the light element 76 correspond to a “notification part” of the present disclosure. The refrigerant sensor 92 is a sensor that detects the occurrence of a refrigerant leak. When a refrigerant leak is detected, the refrigerant sensor 92 sends a signal to the control unit 400 indicating that a refrigerant leak has been detected. The control unit 400 includes a processor 410, such as a CPU or an MPU, a memory 420 and an interface circuit for connecting other devices and sensors. Memory 420 is a storage device that stores programs and data. Memory 420 stores a control program 421 and data to be processed by processor 410. Memory 420 has a non-volatile memory area. Memory 420 also includes a volatile memory area and forms a working area for processor 410. Memory 420 includes, for example, ROM and RAM. The control unit 400 reads the control program 421 stored in memory 420 and executes it to control each part of the refrigerant sensor unit 10 and to perform various operations. The device control unit 400 communicates with the indoor unit 5 via the device communication unit 401. Furthermore, the device control unit 400 triggers an alarm using the buzzer module 74 or the indicator light 76. When the control unit 400 receives a signal from the refrigerant sensor 92, it detects a refrigerant leak and transmits information indicating this leak to the indoor unit 5. The control part 400 corresponds to a “determining part” of the present disclosure. As shown in Figs. 1 and 2, the refrigerant sensor unit 10 is configured to be supplied with electrical energy from a public power grid via a junction box 105 provided on the wall surface 101. In this case, the refrigerant sensor unit 10 is attached to the front of the junction box 105, from which the front panel has been removed, electrically connected to a power supply line E leading to the junction box 105, and is operated. As described above, the refrigerant sensor unit 10 is designed to be powered by electrical energy supplied via a route other than the cable of the remote control RL, and can therefore also be operated even if the refrigerant sensor unit 10 is located, for example, in a room where the indoor unit 5 is not located. Furthermore, the refrigerant sensor unit 10 can also be operated, for example, even if a large number of other devices are connected to the indoor unit 5, to which the refrigerant sensor unit 10 is connected, and consume the amount of power supplied by the indoor unit 5 to the refrigerant sensor unit 10 via the remote control RL. In the present embodiment, the energy supplied by the public power supply via the power supply line E to the refrigerant sensor unit 10 is referred to as the second power supply system. As shown in Fig. 5, the control unit 400 comprises a first power supply unit 430 and a second power supply unit 440. The first power supply unit 430 is a power supply circuit that supplies the refrigerant sensor unit 10 with electrical energy, which is directed to the refrigerant sensor 92. The second power supply unit 440 is a power supply circuit that supplies the refrigerant sensor unit 10 with electrical energy, which is directed to various electrical components, other than the refrigerant sensor 92, that are contained in the refrigerant sensor unit 10. The control unit 400 includes a switch 80. The switch 80 selectively switches either the first power supply system or the second power supply system, so that the first power supply unit 430 can be supplied with power. If the refrigerant sensor unit 10 and the junction box 105 are not connected and an operator mistakenly sets the switch 80 so that power is supplied from the second power supply system to the first power supply unit 430 (external power supply), the refrigerant sensor unit 10 will not function. Therefore, the operator may notice the malfunction of the refrigerant sensor unit 10 during installation. In the case of the refrigerant sensor unit 10, if the power supply is provided from the second power supply system (external power supply) to the first power supply unit 430, while the power supply (power supply for the remote control) from the first power supply system to the first power supply unit 430 is insufficient, there is a risk that an operator will mistakenly set the switch 80 to the power supply (power supply for the remote control) from the first power supply system. Since in such a case the refrigerant sensor unit 10 is connected to the indoor unit 5 or the remote control 7 via the remote control cable RL, it is powered by the first power supply system. Therefore, the refrigerant sensor unit 10 may also be in operation during a test run or similar procedure after the installation of the air conditioner 1. Consequently, there is a risk that the operator will not notice an error in the setting of switch 80. If the air conditioner 1 performs an air conditioning operation in such a state, the power supply from the first power supply system may be insufficient, which can lead to a malfunction in the operation of the refrigerant sensor unit 10. To avoid such a problem, it is desirable that switch 80 be set at the factory when the refrigerant sensor unit 10 is delivered so that the power supply is provided via the second power supply system (external power supply). The refrigerant sensor unit 10 can be connected to the indoor unit 5 via the remote control 7. For example, the refrigerant sensor unit 10 is configured to send and receive signals via a predetermined signal line to and from the outside of the air conditioner 1, such as a control center. For example, the refrigerant sensor unit 10 can detect the refrigerant concentration in the indoor unit 100 and send a detection signal via a signal line to a control center. As shown in Fig. 2, the refrigerant sensor unit 10 is attached to the wall surface 101. As described above, it is desirable to install the refrigerant sensor unit 10 in a lower section of the interior 100 if the refrigerant used by the air conditioning system 1 is a gas with a specific gravity greater than that of air. The refrigerant sensor unit 10 according to the present embodiment is mounted at a position approximately 30 cm above a floor surface 102 of the interior 100. [1-1-5. Structure of the refrigerant sensor unit] Fig. 6 is a perspective view of the refrigerant sensor unit 10. As shown in Fig. 6, the refrigerant sensor unit 10 comprises a housing 12. The housing 12 is in the form of a flat rectangular cuboid with an interior space S1 (Fig. 7). When the refrigerant sensor unit 10 is attached to the interior space 100, the housing 12 is mounted to the wall surface 101 such that a rear wall 20, which has the largest flat surface among the surfaces of the housing 12, faces the wall surface 101. In this case, a front surface 22, located on the side opposite the rear wall 20, is oriented towards the interior space 100. That is, the front surface 22 is located at the front of the housing 12. The refrigerant sensor unit 10 is attached to the wall surface 101 such that a fourth side wall 24, which forms the top of the housing 12, extends in a horizontal direction. Hereinafter, the refrigerant sensor unit 10, attached in this way, is referred to as the "installed state". When the refrigerant sensor unit 10 is in the installed state, a pair of second side walls 26, projecting from the front wall 22, are arranged in positions that serve as side surfaces, and a pair of third side walls 28, projecting from the front wall 22, are arranged in positions that serve as the bottom surface of the housing 12. The third side wall 28 is arranged so that it faces the bottom surface 102. A thin plate element 18 is attached essentially in the center of the front wall 22 of the housing 12. The plate element 18 of the present embodiment is made of plastic and has a thickness of approximately 0.2 mm. The housing 12 is formed by joining a first element 14 and a second element 16. A plastic material is used for both the first element 14 and the second element 16, and the first element 14 and the second element 16 are manufactured, for example, by injection molding. The first element 14 comprises the front wall 22, the pair of second side walls 26, the third side wall 28 and the fourth side wall 24. The pair of second side walls 26, the third side wall 28 and the fourth side wall 24 are designed to project from the front wall 22. The second element 16 comprises the rear wall 20, which forms a rear side of the housing 12. The first element 14 and the second element 16 are connected to each other in a way that allows them to be attached and detached. Therefore, the user can easily access the interior S1 of the housing 12 by disconnecting the connection between the first element 14 and the second element 16. Fig. 7 is a rear view of the refrigerant sensor unit 10. Fig. 7 shows the refrigerant sensor unit 10 in a state in which the second element 16 has been removed. As shown in Fig. 7, a main unit 70 is housed inside the enclosure 12. The main unit 70 comprises a flat, plate-shaped main board 72 and various electronic components mounted on the main board 72. The mainboard 72 corresponds to a “circuit board” of the present disclosure. The buzzer 74, which is an electronic component that emits a notification tone, the several light elements 76, the processor 410 and the memory 420 are mounted on a mounting surface of the mainboard 72, which faces the front wall surface 22. On the main board 72, a terminal block 78, to which various lines such as the remote control line RL and the power supply line E are connected, and a switch 80 are provided on a mounting surface facing the rear wall 20. The switch 80 is, for example, a DIP switch that is operated by an operator installing the refrigerant sensor unit 10 in the interior 100 to switch the connection of the electronic circuit mounted on the main board 72. The mainboard 72 can be equipped with a processor such as a CPU or a GPU, memory, and the like. The connecting block 78 corresponds to a “connecting part” of the present disclosure. The mainboard 72 is covered from its rear by a cover element 82. The cover element 82 is made of a plastic material and is attached to the first element 14 by means of screw elements 99. The cover element 82 is provided with a multitude of recesses 83, which are through holes extending in the direction of the plate thickness. The terminal block 78 and the switch 80 are led out of the cover element 82 through a recess 83. Accordingly, during maintenance work on the refrigerant sensor unit 10, it is prevented that the main board 72 is discharged by the operator touching the main board 72, and wiring work on the terminal block 78 as well as the operation of the switch 80 can be carried out without problems. The cover element 82 is provided with a variety of cable holders 84 that can accommodate various cables connected to the mainboard 72. The cable holder 84, for example, is designed in a rearward-projecting arc shape. A detection unit 90 is housed inside the casing 12. The detection unit 90 comprises a refrigerant sensor 92 and a sensor board 94 on which the refrigerant sensor 92 is mounted. The refrigerant sensor 92 has a column-shaped form and is arranged on the sensor board 94 such that the longitudinal direction of the refrigerant sensor 92 extends perpendicularly from the mounting surface of the flat, plate-shaped sensor board 94. The main board 72 and the sensor board 94 are connected to each other by various lines such as a signal line and a power supply line. As shown in Fig. 7, the switch 80 is located in the interior S1 of the housing 12 at a position near the fourth side wall 24, and the refrigerant sensor 92 is located at a position near the third side wall 28. That is, the switch 80 and the refrigerant sensor 92 are separated from each other within the housing 12. Thus, in the refrigerant sensor unit 10, the user is prevented from coming into contact with the refrigerant sensor 92, even when operating the switch 80. [1-2. Operation] The following describes the operation of the refrigerant sensor unit 10 configured as described above. Fig. 8 is a flowchart illustrating the operation of the refrigerant sensor unit 10. When the refrigerant sensor unit 10 is installed in the interior 100 and put into operation, the control unit 400 determines whether the switch 80 is connected to the first power supply unit 430 so that power can be supplied from the second power supply system (step SA1). If it is determined that the switch 80 is connected to the first power supply unit 430 so that power can be supplied from the second power supply system (step SA1: YES), the control unit 400 determines whether the power supply line E is connected to the refrigerant sensor unit 10 (step SA2). If it is determined that the power supply line E is not connected to the refrigerant sensor unit 10 (step SA2: NO), the control unit 400 determines whether the communication status with the indoor unit 5 is normal (step SA3). The control unit 400 detects that the communication status with the indoor unit 5 is abnormal if there is a deterioration in communication, for example due to a power load on the cable of the remote control RL. If the communication status with indoor unit 5 is detected to be abnormal, the control unit 400 activates the buzzer 74 and the indicator light 76 (step SA4). The control unit 400 then transmits error information to indoor unit 5 (step SA5). As described above, the refrigerant sensor unit 10 is configured to detect whether the refrigerant sensor 92 is receiving sufficient power to operate. This prevents the refrigerant sensor 92 from being interrupted due to a lack of power. As described above, in the refrigerant sensor unit 10, power from one of two different power supply systems can be supplied to the refrigerant sensor 92 by switching the switch 80. Accordingly, in the refrigerant sensor unit 10 it is possible to easily switch between two different power supply systems that can supply power to the refrigerant sensor 92. [1-3. Effects etc.] As described above, in the first embodiment, the refrigerant sensor unit 10 comprises the housing 12, which contains the refrigerant sensor 92 that detects a refrigerant leak. The housing 12 contains the terminal block 78, to which the first and second power supply systems are connected, as well as the first power supply unit 430, which supplies the current provided by the first or second power supply system to the refrigerant sensor 92. Furthermore, the housing 12 contains the switch 80, which selectively connects either the first or the second power supply system to the first power supply unit 430. Thus, in the refrigerant sensor unit 10, current from one of the two different power supply systems can be supplied to the refrigerant sensor 92 by switching the switch 80. Therefore, in the refrigerant sensor unit 10 it is possible to easily switch between two different power supply systems that can supply power to the refrigerant sensor 92. In the present embodiment, the refrigerant sensor unit 10 comprises the control unit 400, which determines whether the first power supply system and the second power supply system are each connected to the terminal block 78, and which determines which of the two systems—the first or the second power supply system—is connected to the first power supply unit 430 by the switch. The refrigerant sensor unit 10 may include the buzzer 74 and the indicator light 76, which issue a notification when the control unit 400 determines that the first power supply system is connected to the terminal block 78, the second power supply system is not connected, and the switch 80 connects the second power supply system to the first power supply unit 430. Accordingly, the refrigerant sensor unit 10 is configured to detect whether the refrigerant sensor 92 is being supplied with sufficient electrical power to operate it. This prevents the operation of the refrigerant sensor 92 from being interrupted due to a lack of power. In the present embodiment, the housing 12 can be designed to be opened and closed, and the switch 80 can be designed to be operated by the user in a state in which the housing 12 is open. Thus, in the refrigerant sensor unit 10, the switch 80 is protected by the housing 12, and the user can easily operate the switch 80 by opening the housing 12. In the present embodiment, the refrigerant sensor 92 and the switch 80 can be arranged separately from each other inside the housing 12. Accordingly, the refrigerant sensor unit 10 prevents the user from coming into contact with the refrigerant sensor 92, even when he operates the switch 80. Furthermore, in the present embodiment, the housing 12 can accommodate a main board, wherein the mounting surface of the main board 72, on which the switch 80 is mounted, is covered with a cover element and the switch 80 protrudes from the cover element. Accordingly, during maintenance work on the refrigerant sensor unit 10, it is prevented that the main board 72 is discharged by the operator touching the main board 72, and wiring work on the terminal block 78 as well as the operation of the switch 80 can be carried out without problems. Furthermore, in the present embodiment, the first power supply system can be a power supply system that uses the power supplied by the indoor unit 5 of the air conditioner 1 as a power source. Thus, the refrigerant sensor unit 10 can be supplied with power under the control of the control part of the indoor unit 200. In the first embodiment described above, the air conditioning unit 1 can, for example, be equipped with a fan that exhausts air from the interior 100 to the outside and a shut-off valve that shuts off the refrigerant line 8. The fan and the shut-off valve can be connected to the indoor unit 5 via a signal line. When the refrigerant sensor unit 10 detects refrigerant, the fan and the shut-off valve can be activated, for example, by the control unit for the indoor unit 200. (Second embodiment) A second embodiment is described below with reference to Fig. 9. Fig. 9 is a schematic diagram illustrating a refrigerant leak detection system 150 according to the second embodiment. In Fig. 9, the same components as in Figs. 1, 2, 3, 4 to 5 are labelled with the same reference numerals, and their description is omitted here. [2-1. Structure] In the second embodiment, the refrigerant used in the air conditioning unit 1, including the indoor unit 5, is a highly flammable or flammable refrigerant, such as R410A, or a refrigerant mixture containing R32, as in the first embodiment. These refrigerants used in the air conditioning unit 1 are gases with a specific gravity greater than that of air. Therefore, in the building where the air conditioning unit 1 is installed, it is desirable to install the refrigerant sensor unit 10 on the lowest floor of the building. If the building has a basement (110), there is a concern that refrigerant leaking from a room on the ground floor could seep down through a gap, such as a door, and reach the basement (110) or the lowest underground level. For this reason, the refrigerant sensor unit (10) can be installed in the basement (110) or the lowest basement level of such a building. If the refrigerant sensor unit 10 is installed in basement 110, the indoor unit 3 may not be installed in basement 110. In such a case, basement 110 can be equipped with the refrigerant leak detection system 150, as shown in Fig. 9. The refrigerant leak detection system 150 includes the refrigerant sensor unit 10, the junction box 105, a fan 160 and a monitoring unit 170. The cellar 110 is equipped with the fan 160. The fan 160 is a pumping device, such as a blower, capable of extracting air from inside the cellar 110 to the outside. The fan 160 is connected to the refrigerant sensor unit 10 via the signal line SL. The fan 160 and the refrigerant sensor unit 10 can communicate with each other via the signal line SL. The fan 160 is supplied with electrical power via the power supply line E from the junction box 105. The fan 160 can also be powered via the refrigerant sensor unit 10, but this is not the only option. The monitoring unit 170 is located in a central monitoring room 120, which is situated outside the basement 110. The monitoring unit 170 comprises a control unit 172, a communication unit 174, and a notification unit 176. The device control part 172 includes a memory and a processor, controls each part of the monitoring unit 170 and performs various operations by reading and executing a program stored in memory. The device communication part 174 comprises communication hardware that conforms to a predefined communication standard, such as a communication circuit, and communicates under the control of the device control part 172 via an external relay with the refrigerant sensor unit 10, which is connected via the device wiring DL, which is a communication line. The notification unit 176, under the control of the control unit 172, triggers an alarm by emitting light or sound. In the monitoring unit 170, the control part 172 can be omitted, and the notification part 176 can trigger 10 different alarms based on a signal from the refrigerant sensor unit. In the first embodiment, the refrigerant leak detection system 150 does not include either the indoor unit 5 or the remote control 7. Therefore, unlike the first embodiment, there is no power supply via the first power supply system using the remote control cable RL. That is, in the refrigerant leak detection system 150, the power supply to the individual components is provided via the second power supply system using the power supply line E from the public power grid. [2-2. Operation] When the refrigerant sensor unit 10 detects refrigerant, the control unit 400 sends a control signal to the fan 160. After receiving the control signal, the fan 160 starts to run, and the air in the basement 110 is extracted to the outside. Furthermore, the control unit 400 sends a signal via an external relay to the monitoring unit 170, indicating that a refrigerant leak has been detected. Upon receiving the signal, the control unit 172 causes the notification unit 176 to trigger an alarm, thus informing the operator that a refrigerant leak has occurred in basement 110. In the present embodiment, the refrigerant sensor unit 10 is a unit contained within the refrigerant leakage detection system 150. However, the present invention is not limited thereto, and as described in the first embodiment, the refrigerant sensor unit 10 can be a unit contained within the air conditioning system 1. In this case, the refrigerant sensor unit 10 can include a switching element capable of toggling the setting between the unit contained in the air conditioning unit 1 and the unit contained in the refrigerant leakage detection system 150. The switching element can, for example, be a changeover switch provided in the control unit 400, essentially corresponding to switch 80. As described in the first embodiment, the refrigerant sensor unit 10, when provided as a unit contained in the air conditioner 1, can be connected to the indoor unit 3 and the remote control 7, and a safety device such as a fan or a shut-off valve can be communicatively connected to the indoor unit 5. In this case, the operator can operate the switch to adjust the units contained in air conditioner 1. Therefore, if the refrigerant sensor unit 10 in the air conditioning system 1 detects refrigerant, a signal is sent from the refrigerant sensor unit 10 to the indoor unit 5, and the control unit 200 of the indoor unit controls safety devices such as a fan and a shut-off valve. If, on the other hand, the refrigerant sensor unit 10 is intended as a unit belonging to the refrigerant leakage detection system 150, the refrigerant sensor unit 10 can be directly connected to the fan 160 in order to communicate with each other. In this case, the operator can operate the switch to adjust the units contained in the refrigerant leak detection system 150. Therefore, if the refrigerant sensor unit 10 in the refrigerant leak detection system 150 detects refrigerant, a signal is sent from the refrigerant sensor unit 10 to control the fan 160. In a case where the remote control cable RL is connected to the refrigerant sensor unit 10, while the switch described above is set to the units contained in the refrigerant leakage detection system 150, there is a risk that the switch will be switched incorrectly ( ). In this case, the control unit 400 can activate the buzzer 74 or the indicator light 76 to issue a notification. Similarly, if the remote control cable RL is not connected to the refrigerant sensor unit 10, while the switch described above is set to the unit contained in the air conditioner 1, there is a risk that the switch may have been switched incorrectly. In this case as well, the control unit 400 can activate the buzzer 74 or the indicator light 76 to issue a notification. (Other embodiments) As described above, the first embodiment was described as an example of the technology disclosed in the present application. However, the technology of the present disclosure is not limited to this and is also applicable to embodiments in which modifications, substitutions, additions, omissions, and the like are made. Furthermore, it is also possible to form a new embodiment by combining the components described in the first embodiment. The refrigerant sensor unit 10 can detect the refrigerant concentration in the indoor unit 100 and transmit a detection signal via the remote control line to the control unit of the indoor unit 200. Upon receiving the detection signal, the control unit of the indoor unit 200 can cause each part of the air conditioner 1 to perform a process related to measures against refrigerant leaks, such as displaying a predetermined message on the display unit of the remote control 302 or performing an air supply process through the indoor unit 5. In this way, the air conditioner 1 can suppress an increase in the refrigerant concentration in the indoor unit 100. Processors 210, 310, and 410 can be implemented as a single processor or as multiple processors. These processors are configured in hardware to implement the corresponding functional components. This means, for example, that these processors can be implemented as an application-specific integrated circuit (ASIC) or a field-programmable gate array (FPGA). The configuration of each part of the air conditioner 1 in Figures 3, 4 to 5 is an example, and a specific embodiment is not particularly limited. That is, it is not always necessary to implement separate hardware for each part, and it is also possible to choose a configuration in which a processor executes a program to realize the function of each part. Some of the functions implemented by software in the embodiments described above can be implemented by hardware, or some of the functions implemented by hardware can be implemented by software. The step unit of the process shown in Fig. 8 is subdivided according to the main processing content for better understanding of the process, and the process is not limited by the type of subdivision of the processing unit or its designation. The processing can be further subdivided into step units according to the processing content. Furthermore, a step unit can be subdivided to include additional processes. The sequence of steps can be modified accordingly without deviating from the spirit of this disclosure. It should be noted that, since the embodiments described above serve to illustrate the technology of the present disclosure, various modifications, substitutions, additions, omissions and the like may be made within the scope of the claims or their equivalents. (Notes) The following techniques are disclosed by the above description of the embodiments. (Method 1) A refrigerant sensor unit comprises a housing containing a refrigerant sensor that detects a leak of refrigerant. The housing accommodates a connection part to which a first power supply system and a second power supply system are connected, as well as a first power supply part that supplies the current provided by the first power supply system or the second power supply system to the refrigerant sensor, and a switch that selectively connects either the first power supply system or the second power supply system to the first power supply part. Accordingly, by switching the switch in the refrigerant sensor unit, it is possible to supply the refrigerant sensor with electrical energy from one of two different power supply systems. Therefore, it is possible in the refrigerant sensor unit to easily switch between two different power supply systems that can power the refrigerant sensor. (Method 2) The refrigerant sensor unit according to Method 1, further comprising: a determining part that determines whether the first power supply system and the second power supply system are each connected to the connecting part and which of the two systems is connected to the first power supply part by the switch; and a notification part that performs a notification when the determining part determines that the first power supply system is connected to the connecting part, the second power supply system is not connected and the switch connects the second power supply system to the first power supply part. The refrigerant sensor unit is therefore configured to detect whether it is receiving sufficient electrical power to operate the sensor. This prevents the sensor's operation from being impaired due to a lack of electrical power. (Technology 3) The refrigerant sensor unit according to Technology 1 or Technology 2, wherein the housing is designed to be opened and closed, and the switching part is a switch designed to be actuated in a state in which the housing is open. Accordingly, in the refrigerant sensor unit, the switch is protected by the housing, and a user can easily operate the switch by opening the housing. (Technology 4) The refrigerant sensor unit according to Technology 3, wherein the refrigerant sensor and the switch are arranged separately from each other inside the housing. Accordingly, the refrigerant sensor unit prevents the user from coming into contact with the refrigerant sensor, even when he or she operates the switch. (Technology 5) The refrigerant sensor unit according to Technology 3 or Technology 4, wherein the housing accommodates a printed circuit board, wherein a mounting surface on which the switch is mounted is covered by a cover element and the switch protrudes from the cover element. Accordingly, during maintenance work on the refrigerant sensor unit, it is possible to prevent the circuit board from being discharged by contact with it by an operator, and wiring work and operation of the switch can be carried out without problems. (Technique 6) The refrigerant sensor unit according to one of techniques 1 to 5, wherein the first power supply system is a power supply system that uses power supplied by an indoor unit of an air conditioner as its power source. Thus, the refrigerant sensor unit can be powered by the control unit contained in the indoor unit. Industrial applicability The present disclosure is applicable to a refrigerant sensor unit installed in a room to be air-conditioned by an air conditioning system. In particular, the present disclosure is applicable, for example, to a refrigerant sensor unit provided outside an indoor unit of an air conditioning system and attached to an interior space air-conditioned by the air conditioning system. List of reference symbols 1 Air conditioner 3 Outdoor unit 5 Indoor unit 6 Air outlet 7 Remote control 8 Refrigerant line 9 Cooling circuit 10 Refrigerant sensor unit 12 Housing 14 First element 16 Second element 18 Sheet metal 20 Rear panel 22 Front panel 24 Fourth side panel 26 Second side panel 28 Third side panel 40 Unit control unit 70 Main unit 72 Main board 74 Buzzer 76 Indicator light 78 Terminal block 80 Switch 82 Cover element 83 Recess 84 Cable holder 90 Detection unit 92 Refrigerant sensor 94 Sensor board 99 Screw element 100 Interior 101 Wall surface 102 Floor surface 105 Junction box 110 Basement 120 Central monitoring room 150 Refrigerant leak detection system 160 Fan 170 Monitoring unit 172 Unit control unit 174 Unit communication unit 176 Unit notification unit 200 Control unit for indoor unit 201 Communication unit of the first indoor unit 202 Second communication unit of the indoor unit 210, 310, 410 Processor 220, 320, 420 Memory 221, 321,421 Control program 300 Remote control control unit 301 Communication unit of the remote control 302 Display unit of the remote control 303 Operating element of the remote control 400 Control unit for devices 401 Device communication unit 430 First power supply unit 440 Second power supply unit CL Communication line DL Device wiring E Power supply line RL Cable for the remote control SL Signal line S1 Interior,

Claims

A refrigerant sensor unit comprising: a housing accommodating a refrigerant sensor configured to detect a refrigerant leak, the housing accommodating: a connecting part to which a first power supply system and a second power supply system are connected; a first power supply unit configured to supply the current provided by the first power supply system or the second power supply system to the refrigerant sensor; and a switch selectively connecting either the first power supply system or the second power supply system to the first power supply unit. The refrigerant sensor unit according to claim 1, further comprising: a determining part configured to determine whether the first power supply system and the second power supply system are each connected to the connecting part and which of the two systems is connected to the first power supply part by the switch; a notification part configured to issue a notification when the determining part determines that the first power supply system is connected to the connecting part, the second power supply system is not connected to the connecting part, and the switch connects the second power supply system to the first power supply part. Refrigerant sensor unit according to claim 1 or claim 2, wherein the housing is designed to be opened and closed; and the switching element is a switch designed to be able to be switched in a state in which the housing is open. Refrigerant sensor unit according to claim 3, wherein the refrigerant sensor and the switch are arranged separately from each other within the housing. The refrigerant sensor unit according to claim 3, wherein the housing accommodates a circuit board with a mounting surface, wherein the switch is mounted on the mounting surface and the mounting surface is covered with a cover element; and the switch protrudes from the cover element. The refrigerant sensor unit according to claim 1 or claim 2, wherein the first power supply system is a power supply system that uses power supplied by an indoor unit of an air conditioner as a power source.

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