Refrigerant leak detection device and refrigeration cycle device

Abstract

The refrigerant leak detection device includes a memory unit that stores time-series data of the output of a gas sensor that detects gas, and a control device that determines the pattern of the output of the gas sensor from the time-series data stored in the memory unit and determines whether or not a refrigerant leak has occurred based on the pattern.

Description

[Technical Field]

[0001] The present disclosure relates to a refrigerant leak detection device that detects refrigerant leaks and a refrigeration cycle device. [Background technology]

[0002] Refrigeration cycle devices, such as air conditioners commonly referred to as air conditioners or freezers installed in food warehouses, cool or heat indoor spaces using the heat pump principle. Recent heat pumps use mildly flammable or combustible refrigerants with low fluorocarbon layer destruction coefficients. When mildly flammable or combustible refrigerants are used, there is a risk of fire if the refrigerant leaks from the refrigeration cycle device. Therefore, it is known to provide the refrigeration cycle device with a refrigerant detection means that detects refrigerant gas and an alarm that sounds when the refrigerant detection means detects refrigerant gas (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2021-124236 Summary of the Invention [Problem to be solved by the invention]

[0004] Currently known refrigerant detection methods include semiconductor, NDIR (infrared absorption), and thermal conduction gas sensors. If a gas with similar chemical properties to the refrigerant gas, such as hairspray, is used in an indoor space where a refrigeration cycle device equipped with such a gas sensor is installed, the gas sensor may mistakenly detect the spray gas as a refrigerant leak.

[0005] The present disclosure is intended to solve the above-mentioned problems, and aims to provide a refrigerant leak detection device and a refrigeration cycle device that can reduce false detections of refrigerant leaks. [Means for solving the problem]

[0006] A refrigerant leak detection device according to the present disclosure includes a storage unit that stores time-series data of the output of a gas sensor that detects gas, and a control device that determines a pattern of the output of the gas sensor from the time-series data stored in the storage unit and determines whether or not a refrigerant leak has occurred based on the pattern. The control device determines an index including at least one of a second derivative value, a peak value, a half-width, and a sharpness from the time series data stored in the storage unit, and compares the index with a preset threshold value to determine whether a refrigerant leak has occurred. This is what is done.

[0007] The refrigeration cycle device of the present disclosure includes the above-mentioned refrigerant leak detection device, a gas sensor, an indoor heat exchanger that constitutes a refrigerant circuit, an indoor fan that sends air to the indoor heat exchanger, and an alarm device that issues a warning if the refrigerant leak detection device determines that a refrigerant leak has occurred. [Effects of the Invention]

[0008] According to the refrigerant leak detection device and refrigeration cycle device of the present disclosure, it is possible to reduce false detections of refrigerant leaks by determining whether or not a refrigerant leak has occurred based on a pattern obtained from time-series data of the output of the gas sensor. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is an external view of a refrigeration cycle device according to a first embodiment. [Figure 2] 1 is a diagram schematically showing an internal structure of a refrigeration cycle device according to a first embodiment. [Figure 3] FIG. 10 is a diagram illustrating experimental verification in the model space TR. [Figure 4] 4 is a graph showing the change over time in the output voltage of the gas sensor when a refrigerant leaks. [Figure 5] 10 is a graph showing the change over time in the output voltage of the gas sensor during spray ejection. [Figure 6] 1 is a control block diagram of a refrigeration cycle device according to a first embodiment. [Figure 7]4 is a flowchart showing the flow of a refrigerant leakage detection process in the first embodiment. [Figure 8] 10 is a flowchart showing the flow of a refrigerant leakage detection process in the second embodiment. [Figure 9] FIG. 10 is a control block diagram of a refrigeration cycle device according to a third embodiment. [Figure 10] 11 is a flowchart showing the flow of a refrigerant leakage detection process in the third embodiment. [Figure 11] FIG. 10 is a diagram schematically showing the internal structure of a refrigeration cycle device according to a fourth embodiment. [Figure 12] FIG. 4 is a diagram showing temporal changes in the output voltage of the first gas sensor and the output voltage of the second gas sensor when a refrigerant leaks. [Figure 13] FIG. 4 is a diagram showing the time changes in the output voltage of the first gas sensor and the output voltage of the second gas sensor during spray ejection. [Figure 14] 10 is a flowchart showing the flow of a refrigerant leakage detection process in the fourth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In each drawing, identical or corresponding parts are denoted by the same reference numerals, and their description will be omitted or simplified as appropriate. Furthermore, the shape, size, arrangement, etc. of the configurations shown in each drawing may be modified as appropriate within the scope of the present disclosure.

[0011] Embodiment 1 FIG. 1 is an external view of a refrigeration cycle apparatus 100 according to a first embodiment. FIG. 2 is a diagram schematically illustrating the internal structure of the refrigeration cycle apparatus 100 according to the first embodiment. FIGS. 1 and 2 are diagrams illustrating the refrigeration cycle apparatus 100 as viewed from the front. The refrigeration cycle apparatus 100 according to this embodiment is an indoor unit of a floor-standing air conditioner that is installed on the floor of an indoor space to be air-conditioned. The refrigeration cycle apparatus 100 is not limited to a floor-standing indoor unit, and may be, for example, an indoor unit or a refrigerator of a wall-mounted or ceiling-mounted air conditioner. In the following description, the positional relationship between the components (e.g., vertical relationship) refers to the relationship when the refrigeration cycle apparatus 100 is installed and ready for use.

[0012] As shown in FIG. 1, the refrigeration cycle apparatus 100 includes a housing 1 that forms an outer shell. The housing 1 has a rectangular parallelepiped shape with six sides: a front, a rear, a top, a bottom, a left side, and a right side. An air inlet 11 is provided at the bottom of the front of the housing 1, and an air outlet 12 is provided at the top of the front. A remote control 13 is also provided on the front of the housing 1. The remote control 13 has an operation display unit 131 that is configured with a touch panel or the like. The operation display unit 131 displays the operation mode of the refrigeration cycle apparatus 100, the room temperature, the set temperature, and messages such as errors or warnings. User instructions such as the operation mode and set temperature are also input via the operation display unit 131.

[0013] 2, an indoor heat exchanger 2, an indoor fan 3, a flare section 4, a gas sensor 5, and a control device 6 are provided inside a housing 1 of the refrigeration cycle apparatus 100. The refrigeration cycle apparatus 100 draws air from an indoor space through an air inlet 11 using the indoor fan 3, moves the drawn air to the upper part of the housing 1, exchanges heat with a refrigerant in the indoor heat exchanger 2, and blows the air out into the indoor space through an air outlet 12, thereby cooling or heating the indoor space.

[0014] The indoor heat exchanger 2 is, for example, a fin-tube heat exchanger, and exchanges heat between the refrigerant flowing inside the heat transfer tubes and the air blown by the indoor fan 3. The indoor heat exchanger 2 constitutes a refrigerant circuit together with a compressor, an outdoor heat exchanger, and a pressure reducing device (none of which are shown) provided in an outdoor unit located outdoors. The refrigerant circulates in the refrigerant circuit, allowing the refrigeration cycle apparatus 100 to cool and heat the indoor space.

[0015] A flammable refrigerant such as R32 (CH2F2) is used as the refrigerant circulating through the refrigerant circuit of the refrigeration cycle device 100. Even if the flammable refrigerant leaks into the indoor space, it will not ignite if the refrigerant concentration in the indoor space is low. Here, the lower limit concentration at which the flammable refrigerant ignites is referred to as the ignition concentration. The ignition concentration of R32 is 0.3 kg / m when calculated based on the molecular weight of R32 of 52 and room temperature of 25°C. 3 The concentration is 14.4%. As the refrigerant, in addition to R32, a slightly flammable refrigerant such as TR234yf or TR234ze(E), a highly flammable refrigerant such as R290 or TR270, or a non-flammable refrigerant such as R22 or R410A may be used.

[0016] The indoor fan 3 draws in air from the indoor space, passes it through the indoor heat exchanger 2, and blows it out into the indoor space. The indoor fan 3 is, for example, a sirocco fan or a crossflow fan driven by a motor. The air volume (rotation speed) of the indoor fan 3 is controlled by a control device 6.

[0017] The flare section 4 is a location where an installer performs piping connection work at the installation location of the refrigeration cycle apparatus 100. Specifically, the flare section 4 is a portion where indoor pipes 41 and 42 connected to the indoor heat exchanger 2 are connected to extension pipes 43 and 44 outside the casing 1 using, for example, flare joints. If refrigerant leaks from the flare section 4 due to an installation error during installation of the refrigeration cycle apparatus 100, for example, the refrigerant will accumulate in the stagnation section 15, which is the lower space within the casing 1, because the refrigerant has a higher specific gravity than air. The refrigerant accumulated in the stagnation section 15 will eventually leak into the room from the suction port 11.

[0018] The gas sensor 5 is disposed in the stagnation portion 15. The gas sensor 5 detects gas and outputs a voltage [V] corresponding to the concentration of the detected gas. The output of the gas sensor 5 is not limited to a voltage, but may output a concentration or a value corresponding to the concentration. The gas sensor 5 is, for example, a semiconductor gas sensor, a thermal conduction sensor, or an NDIR (infrared absorption) sensor. The output from the gas sensor 5 is input to the control device 6 periodically (for example, every minute) and stored in the memory unit 61 (FIG. 6).

[0019] The control device 6 is configured by a computer including a memory for storing data and programs required for control and a processor such as a CPU for executing the programs, a dedicated processing circuit such as an ASIC or FPGA, or both. In FIG. 1, the control device 6 is provided inside the housing 1 of the refrigeration cycle apparatus 100, but it may also be provided outside the housing 1, for example, in an outdoor unit. The control device 6 controls the operation of the refrigeration cycle apparatus 100 based on instructions from a user input via a remote control 13 and the operating state of the refrigeration cycle apparatus 100. The control device 6 of this embodiment also performs a refrigerant leakage detection process, which will be described later, based on the output of the gas sensor 5.

[0020] The gas sensor 5 used to detect refrigerant leakage also detects gases other than the refrigerant gas leaking from the refrigeration cycle apparatus 100. The reason for this will be explained below.

[0021] The principle of refrigerant gas detection when a semiconductor gas sensor is used as the gas sensor 5 will be explained. The semiconductor gas sensor incorporates a sensor element whose main raw material is tin oxide, and oxygen in the air is adsorbed to the surface of the tin oxide when electricity is applied. When the refrigerant gas, which is a reducing gas, approaches the sensor element, the oxygen on the tin oxide surface is removed, i.e., a reduction reaction occurs, causing the resistance value of the sensor element to decrease. The semiconductor gas sensor converts this resistance value into a voltage and outputs it as the sensor output. In this case, hairspray gas or oil, both of which are reducing gases, are detected by the semiconductor gas sensor in the same way as the refrigerant gas.

[0022] This section explains the principle of refrigerant gas detection when a thermal conduction sensor is used as the gas sensor 5. Different types of gas have different thermal conductivities. The area around a hot wire, such as platinum, is heated. When refrigerant gas reaches the vicinity of the hot wire, the thermal conductivity changes, causing a change in the resistance of the hot wire. The thermal conduction sensor converts this resistance value into a voltage and outputs it as the sensor output. Because the thermal conductivity of gases varies depending on the molecular size and functional groups, it is theoretically possible to distinguish between gases with significantly different molecular sizes and functional groups. However, it is difficult to distinguish between refrigerant gases and chemically similar gases. Therefore, gases such as hairspray gases, which are chemically similar to refrigerant gases, can be detected by a thermal conduction sensor in the same way as refrigerant gases.

[0023] The detection principle of refrigerant gas when an NDIR sensor is used as the gas sensor 5 is explained below. Different types of gases have different degrees of infrared absorption. Refrigerant gases generally have an absorption band near a wavelength of 3.3 μm, so an NDIR sensor measures the infrared absorbance, converts the absorbance into a voltage, and outputs it as the sensor output. Because the absorption band of a gas depends on the functional group, it is difficult to distinguish between gases that have the same functional group as refrigerant gas. Therefore, gases such as hairspray gases that have the same functional group as refrigerant gas can be detected by a thermal conduction sensor in the same way as refrigerant gas.

[0024] For example, hair spray is commonly used in beauty salons. Hair spray contains compressed flammable gas, and spraying can fill the room with flammable gas, often causing a false alarm in a gas sensor. In this case, it is difficult to take countermeasures when a store previously used for purposes other than a beauty salon is repurposed as a beauty salon. Furthermore, in addition to hair sprays used in beauty salons, other products, such as insecticide sprays and skin-cooling sprays, often temporarily release flammable gases into a room. In this case, whether a semiconductor gas sensor, a thermal conduction sensor, or an NDIR sensor is used, the gas from the spray may be detected, leading to a false detection of a refrigerant leak in a conventional refrigeration cycle system. In this case, implementing countermeasures against refrigerant leaks, such as issuing an alarm due to a false detection, can cause anxiety among users and increase the workload of service personnel managing the refrigeration cycle system 100.

[0025] Therefore, the inventors conducted an experimental verification in a model space in order to reduce false detection of refrigerant leakage due to spray injection. Figure 3 is a diagram for explaining the experimental verification in the model space TR. As shown in Figure 3, a store with a volume of, for example, 20 m is assumed in which the spray 8 is used. 3 A refrigeration cycle apparatus 100, which is an indoor unit of an air conditioner, was installed in the model space TR and filled with R32 as a refrigerant. An experiment was then conducted to reproduce the environment in which a refrigerant leak occurs. Specifically, the refrigeration cycle apparatus 100 was operated in cooling mode, and the screwed portion of the flare portion 4 was loosened without spraying the spray 8 to simulate a refrigerant leak, and the change in the output voltage of the gas sensor 5 over time was determined.

[0026] 4 is a graph showing the change over time in the output voltage of the gas sensor 5 when a refrigerant leaks. The horizontal axis of FIG. 4 is time, and the vertical axis is the output voltage [V] of the gas sensor 5. When the refrigerant leaks, the refrigerant gas diffuses in the stagnation portion 15 and reaches the gas sensor 5, resulting in a pattern in which the output voltage gradually increases over time. After the output voltage increases, depending on the operating state of the refrigeration cycle apparatus 100, the output voltage may continue to increase, become constant due to saturation, or decrease due to natural diffusion.

[0027] Next, the experimental conditions were initialized, and an experiment was conducted that reproduced the environment of spray injection. Specifically, the refrigeration cycle apparatus 100 was operated in cooling mode, and gas was sprayed from the spray 8 for one minute without loosening the screwed portion of the flare portion 4, and the change in the output voltage of the gas sensor 5 over time was determined. FIG. 5 is a graph showing the change in the output voltage of the gas sensor 5 over time during spray injection. The horizontal axis of FIG. 5 is time, and the vertical axis is the output voltage [V] of the gas sensor 5. As shown in FIG. 5, in the case of spray injection, the sensor output increased over time and then decreased.

[0028] Comparing the output voltage patterns during a refrigerant leak in FIG. 4 and the output voltage patterns during a spray injection in FIG. 5, it is possible to distinguish between a refrigerant leak and a spray injection from the output voltage pattern of the gas sensor 5. The pattern described here refers to the shape of the time-series data of the output voltage of the gas sensor 5 when it is represented in a graph, and to a characteristic index determined from the time-series data. The characteristic index may be, for example, at least one of the peak value, half-width, sharpness, first derivative, and second derivative of the output voltage. As shown in FIG. 5, the half-width is the time width exceeding half the peak value, which is half the peak value of the output voltage. The sharpness is the value obtained by dividing the peak value by the half-width. Alternatively, the sharpness may be a value obtained by dividing the peak value by a time width other than the half-width. Experiments have shown that the output voltage pattern of the gas sensor 5 during a spray injection has smaller peak value, half-width, sharpness, first derivative, and second derivative than the output voltage pattern during a refrigerant leak.

[0029] Fig. 6 is a control block diagram of the refrigeration cycle apparatus 100 according to the first embodiment. As shown in Fig. 6, the control device 6 has a storage unit 61, a determination unit 62, a timing unit 63, and a control unit 64. The determination unit 62, the timing unit 63, and the control unit 64 are functional units that are realized by a processor included in the control device 6 executing a program stored in a memory, or that are realized by a dedicated processing circuit.

[0030] The storage unit 61 is configured with, for example, a volatile or non-volatile semiconductor memory such as a RAM, a ROM, or a flash memory. The storage unit 61 stores time-series data of the output of the gas sensor 5. The storage unit 61 also stores a program used in the refrigerant leakage detection process of the control device 6, and various data such as calculation formulas and thresholds used in executing the program.

[0031] The determination unit 62 determines whether a refrigerant leak has occurred based on the time-series data of the output voltage of the gas sensor 5 stored in the storage unit 61. Specifically, the determination unit 62 determines whether the output voltage of the gas sensor 5 is greater than a first threshold value. The first threshold value is set in advance as a voltage corresponding to a concentration that is lower than the ignition concentration, and is stored in the storage unit 61. There are no particular limitations on how much lower the alert concentration should be set compared to the ignition concentration, but the alert concentration is set, for example, within a range of 0.01 to 10% of the ignition concentration. For example, for R32, the range is 14.4 ppm to 14,400 ppm.

[0032] Furthermore, when the output voltage of the gas sensor 5 is greater than the first threshold, the determination unit 62 determines whether there is a refrigerant leak or spray injection based on the time-series data of the output voltage. For example, when the output voltage of the gas sensor 5 does not decrease even after a preset waiting time has elapsed since it became greater than the first threshold, the determination unit 62 determines that there is a refrigerant leak. The waiting time is, for example, 30 to 60 seconds. Furthermore, the determination unit 62 calculates the peak value from the time-series data of the output voltage of the gas sensor 5 stored in the storage unit 61, and when the peak value is less than a preset second threshold, determines that there is spray injection. The second threshold is calculated by a previously conducted experiment or is set using the results of calculations by simulation, and is stored in the storage unit 61.

[0033] The determination unit 62 may determine that spray injection has occurred when the half-width of the output voltage of the gas sensor 5 is less than a preset threshold value. Alternatively, the determination unit 62 may calculate a first derivative or a second derivative value as the output voltage of the gas sensor 5 increases, and determine that spray injection has occurred when each derivative value is less than a preset threshold value. The threshold values ​​used for these determinations are also determined by experiments carried out in advance, or are set using results calculated by simulation, and are stored in the storage unit 61.

[0034] The timer 63 measures the time that has elapsed since the output voltage of the gas sensor 5 became greater than the first threshold value. The measurement result of the timer 63 is output to the determination unit 62.

[0035] When the determination unit 62 determines that a refrigerant leak has occurred, the control unit 64 controls the indoor fan 3 and the remote control 13 to implement measures to prevent the refrigerant leak. Specifically, when the determination unit 62 determines that a refrigerant leak has occurred, the control unit 64 starts operation of the indoor fan 3 or increases the rotation speed to diffuse the refrigerant in the stagnation portion 15. Furthermore, when the determination unit 62 determines that a refrigerant leak has occurred, the control unit 64 displays a warning on the operation display unit 131 of the remote control 13 to notify the user of the refrigerant leak. Alternatively, the remote control 13 may be provided with a speaker or the like to emit an alarm to notify the user of the refrigerant leak. Note that the notification to the user in the event of a refrigerant leak is not limited to being performed by the remote control 13. For example, a separate alarm device may be installed to issue the alarm. Alternatively, the notification may be sent directly to an information terminal such as a smartphone carried by the user.

[0036] 7 is a flowchart showing the flow of the refrigerant leakage detection process in the first embodiment. First, the determination unit 62 of the control device 6 determines whether the output voltage of the gas sensor 5 is greater than the first threshold value (S1). If the output voltage of the gas sensor 5 is equal to or less than the first threshold value (S1: NO), the process returns to step S1. If the output voltage of the gas sensor 5 is greater than the first threshold value (S1: YES), the process determines that the alarm level is L1 (S2). At the alarm level L1, the control unit 64 does not implement any countermeasures against refrigerant leakage. Alternatively, at the alarm level L1, a minor countermeasure may be implemented, such as displaying a warning on the operation display unit 131 of the remote control 13 that there is a possibility of refrigerant leakage.

[0037] The timer 63 starts measuring the time since the output voltage became greater than the first threshold (S3). Then, the determination unit 62 determines whether the output voltage of the gas sensor 5 has decreased (S4). If the output voltage of the gas sensor 5 has not decreased (S4: NO), the determination unit 62 determines whether the standby time has elapsed based on the measurement result of the timer 63 (S5). If the standby time has not elapsed (S5: NO), the process returns to step S4. If the standby time has elapsed (S5: YES), the process determines that the alarm level is L2 (S6).

[0038] The warning level L2 is the warning level to be issued when a refrigerant leak occurs. If the output voltage of the gas sensor 5 does not decrease even after a waiting time has elapsed since exceeding the first threshold, there is a high possibility that a refrigerant leak has occurred. Therefore, in this case, the determination unit 62 determines that the warning level is L2, and the control unit 64 implements measures to prevent the refrigerant leak (S7). Specifically, the control unit 64 causes the remote control 13 to display or sound a warning to notify the user of the refrigerant leak, and to start operating the indoor fan 3 or increase the airflow rate.

[0039] On the other hand, if the output voltage of the gas sensor 5 drops before the standby time has elapsed (S4: YES), the determination unit 62 calculates the peakiness from the time-series data of the output voltage of the gas sensor 5 stored in the storage unit 61 (S8). Then, the determination unit 62 determines whether the peakiness is less than a second threshold value (S9). If the peakiness is equal to or greater than the second threshold value (S9: NO), the determination unit 62 determines that the alarm level is L2 (S6) and takes measures to prevent refrigerant leakage (S7).

[0040] If the peakiness is less than the second threshold (S9: YES), the determination unit 62 determines whether the current output voltage of the gas sensor 5 is greater than the first threshold (S10). If the current output voltage of the gas sensor 5 is greater than the first threshold (S10: YES), the process returns to step S10 and maintains the alarm level L1. On the other hand, if the current output voltage of the gas sensor 5 is equal to or less than the first threshold (S10: NO), the alarm is canceled (S11) and this process ends. That is, if the peakiness is less than the second threshold, the determination unit 62 determines that the occurrence is a spray rather than a refrigerant leak, and cancels the alarm as it is not necessary to notify the user.

[0041] As described above, the refrigeration cycle apparatus 100 of this embodiment determines whether a refrigerant leak or a spray is occurring based on the time-series data of the output voltage of the gas sensor 5 and the pattern determined from the time-series data. This reduces false detections due to the sudden generation of gas other than the refrigerant gas, such as a spray.

[0042] Embodiment 2 A second embodiment will be described. The second embodiment differs from the first embodiment in the refrigerant leakage detection process. The configuration of the refrigeration cycle apparatus 100 is the same as that of the first embodiment.

[0043] 8 is a flowchart showing the flow of the refrigerant leakage detection process in the second embodiment. The determination unit 62 of the control device 6 calculates a second derivative value from the time-series data of the output voltage of the gas sensor 5 stored in the storage unit 61 (S101). The determination unit 62 then determines whether the calculated second derivative value is greater than a preset third threshold value (S102). The third threshold value is determined by a previously conducted experiment or is set using the results of calculations performed by simulation, and is stored in the storage unit 61. If the calculated second derivative value is equal to or less than the preset third threshold value (S102: NO), the process returns to step S101.

[0044] On the other hand, if the calculated second-order differential value is greater than the preset third threshold value (S102: YES), the determination unit 62 determines that the alarm level is L1 (S103). The second-order differential value of the output voltage becomes large when the output voltage is on an increasing trend. Therefore, if the second-order differential value is greater than the third threshold value, it can be determined that the output voltage of the gas sensor 5 is increasing and there is a possibility of a refrigerant leak. As in the first embodiment, no refrigerant leakage countermeasures are implemented at the alarm level L1. Alternatively, at the alarm level L1, minor refrigerant leakage countermeasures may be implemented, such as displaying a warning on the remote control 13 that there is a possibility of a refrigerant leak.

[0045] Next, the determination unit 62 calculates a first derivative value from the time-series data of the output voltage of the gas sensor 5 stored in the storage unit 61 (S104). Then, the determination unit 62 determines whether the calculated first derivative value is greater than a preset fourth threshold value (S105). The fourth threshold value is determined by a previously conducted experiment or is set using the results of calculations by simulation, and is stored in the storage unit 61. If the calculated first derivative value is greater than the preset fourth threshold value (S105: YES), the determination unit 62 determines that the alarm level is L2 (S106).

[0046] The warning level L2 is a level that occurs when a refrigerant leak occurs. If the first derivative value of the output voltage of the gas sensor 5 is large, there is a high possibility that a refrigerant leak has occurred. Therefore, in this case, the control device 6 determines that the warning level is L2 and implements measures to prevent the refrigerant leak (S107). Specifically, as in the first embodiment, the control unit 64 causes the remote control 13 to issue a warning display or sound to notify the user of the refrigerant leak, and starts operating the indoor fan 3 or increases the airflow rate.

[0047] On the other hand, if the calculated first differential value is equal to or less than a fourth threshold value set in advance (S105: NO), the determination unit 62 calculates the peak value from the time-series data of the output voltage of the gas sensor 5 stored in the storage unit 61 (S108). Then, the determination unit 62 determines whether the peak value is less than a second threshold value (S109). If the peak value is equal to or greater than the second threshold value (S109: NO), the determination unit 62 determines that the alarm level is L2 (S106) and takes measures to prevent refrigerant leakage (S107).

[0048] If the peakiness is less than the second threshold (S109: YES), the determination unit 62 determines whether the current output voltage of the gas sensor 5 is greater than the first threshold (S110). If the current output voltage of the gas sensor 5 is greater than the first threshold (S110: YES), the process returns to step S110 and maintains the alarm level L1. On the other hand, if the current output voltage of the gas sensor 5 is equal to or less than the first threshold (S110: NO), the alarm is canceled (S111) and the process ends. That is, if the first-order differential value is equal to or less than the fourth threshold and the peakiness is less than the second threshold, the determination unit 62 determines that the occurrence is not a refrigerant leak but a spray injection, and cancels the alarm as it is not necessary to notify the user.

[0049] As described above, in the refrigeration cycle apparatus 100 of this embodiment, a determination is made as to whether a refrigerant leak or a spray is occurring based on the time-series data of the output voltage of the gas sensor 5 and the pattern determined from the time-series data. This makes it possible to reduce false detections due to the sudden generation of gas other than refrigerant gas, such as a spray. Furthermore, by using a combination of multiple indicators as the pattern of the output voltage of the gas sensor 5, the accuracy of determining whether a refrigerant leak or a spray is improved, and false detections can be further reduced.

[0050] Embodiment 3 A third embodiment will be described. The third embodiment differs from the first embodiment in that each threshold value used in the refrigerant leakage detection process is corrected according to the installation environment of the refrigeration cycle apparatus 100A. The configuration of the refrigeration cycle apparatus 100A is the same as that of the first embodiment.

[0051] 9 is a control block diagram of a refrigeration cycle apparatus 100A according to the third embodiment. As shown in FIG. 9, a control device 6A according to the third embodiment includes a storage unit 61, a determination unit 62, a timer 63, a control unit 64, an information acquisition unit 65, and a threshold value correction unit 66. The determination unit 62, the timer 63, the control unit 64, the information acquisition unit 65, and the threshold value correction unit 66 are functional units that are realized by a processor included in the control device 6A executing a program stored in a memory, or that are realized by a dedicated processing circuit. The functions of the storage unit 61, the determination unit 62, the timer 63, and the control unit 64 are the same as those in the first embodiment.

[0052] The information acquisition unit 65 acquires environmental information. The environmental information is information about the environment in which the refrigeration cycle apparatus 100A is installed, and is at least one of the volume, wind speed distribution, ventilation rate, and temperature and humidity of the indoor space in which the refrigeration cycle apparatus 100A is installed. The environmental information may be input by a user or may be actually measured using a sensor installed in the indoor space to measure the environmental information, or may be calculated by simulation. For example, the volume of the indoor space may be input in advance by a user using the remote control 13, or may be determined by analyzing images captured by a camera. The wind speed distribution may be measured using a wind speed sensor, or may be calculated by simulation based on the operating state of the refrigeration cycle apparatus 100A in the indoor space. The ventilation rate may be input by a user or may be acquired by communicating with a ventilation device. The temperature and humidity can be measured using a temperature sensor and a humidity sensor.

[0053] The threshold correction unit 66 corrects each threshold value used in the refrigerant leakage detection process based on the environmental information acquired by the information acquisition unit 65. For example, the threshold correction unit 66 corrects the first and second threshold values ​​so that they are larger as the volume of the indoor space increases. This is because the larger the volume of the indoor space, the greater the allowable amount of refrigerant leakage. The threshold correction unit 66 also corrects the first and second threshold values ​​so that they are larger as the wind speed near the gas sensor 5 increases. This is because refrigerant gas is expected to diffuse quickly when the wind speed near the gas sensor 5 is high (e.g., 1 m / s or higher). The threshold correction unit 66 also corrects the first and second threshold values ​​so that they are larger as the ventilation rate increases. This is because refrigerant gas is expected to diffuse quickly when the ventilation rate is high (e.g., more than twice per hour). The threshold correction unit 66 also corrects the first and second threshold values ​​so that they are smaller as the temperature increases. This is because the higher the temperature, the greater the risk of fire due to refrigerant leakage. Furthermore, the threshold value corrector 66 corrects the first threshold value and the second threshold value so that they become smaller as the humidity decreases, because the lower the humidity, the higher the risk of fire due to refrigerant leakage.

[0054] The threshold correction unit 66 corrects the first threshold and the second threshold based on a table in which the first threshold and the second threshold for each piece of environmental information are set, or a table in which correction values ​​for the first threshold and the second threshold for each piece of environmental information are set. Alternatively, the threshold correction unit 66 may correct the first threshold and the second threshold using a calculation formula that indicates the relationship between the environmental information and the first threshold and the second threshold.

[0055] 10 is a flowchart showing the flow of the refrigerant leakage detection process in the third embodiment. First, the information acquisition unit 65 of the control device 6A acquires environmental information (S201). Then, the threshold correction unit 66 corrects the first threshold and the second threshold based on the acquired environmental information (S202). Thereafter, the refrigerant leakage is detected by the same processes as in the first embodiment, steps S1 to S11. The determination unit 62 makes a determination using the first threshold and the second threshold corrected by the threshold correction unit 66.

[0056] As described above, in the refrigeration cycle apparatus 100A of this embodiment, a determination is made as to whether a refrigerant leak or a spray is occurring based on the time-series data of the output voltage of the gas sensor 5 and the pattern determined from the time-series data. This makes it possible to reduce false detections due to the sudden generation of gas other than refrigerant gas, such as spray. Furthermore, by correcting the first and second thresholds used for the determination in accordance with the environment of the indoor space in which the refrigeration cycle apparatus 100A is installed, the accuracy of determining whether a refrigerant leak or a spray is improved, and false detections can be further reduced.

[0057] The threshold correction unit 66 may correct the third threshold and the fourth threshold in the second embodiment. The tendency of the correction of the third threshold and the fourth threshold is the same as that of the first threshold and the second threshold. For example, the threshold correction unit 66 corrects the third threshold and the fourth threshold so that the larger the volume of the indoor space, the larger the third threshold and the fourth threshold. The threshold correction unit 66 corrects the third threshold and the fourth threshold based on a table in which the third threshold and the fourth threshold for each piece of environmental information are set, or a table in which the correction values ​​of the third threshold and the fourth threshold for each piece of environmental information are set. Alternatively, the threshold correction unit 66 may correct the third threshold and the fourth threshold using a calculation formula indicating the relationship between the environmental information and the third threshold and the fourth threshold.

[0058] The information acquisition unit 65 may also acquire, as environmental information, the presence or absence of a person in the indoor space where the refrigeration cycle apparatus 100A is installed. The presence or absence of a person can be determined by measuring infrared rays emitted by the person using an infrared sensor. If there is no person in the indoor space where the refrigeration cycle apparatus 100A is installed, the determination unit 62 may omit the processes of steps S8 and S9 because it is considered that spray ejection is unlikely to occur.

[0059] Embodiment 4 A fourth embodiment will be described. The fourth embodiment differs from the first embodiment in that the refrigeration cycle apparatus 100B includes two gas sensors arranged at different positions, and the refrigerant leakage detection process is performed based on time-series data of the output voltages of the two gas sensors.

[0060] FIG. 11 is a diagram schematically illustrating the internal structure of a refrigeration cycle apparatus 100B according to the fourth embodiment. FIG. 11 is a diagram illustrating the refrigeration cycle apparatus 100B as viewed from the front. As shown in FIG. 11, the refrigeration cycle apparatus 100B according to the fourth embodiment includes a first gas sensor 51 disposed near the indoor fan 3 and a second gas sensor 52 disposed near the flare section 4. The first gas sensor 51 and the second gas sensor 52 are, for example, semiconductor gas sensors, thermal conduction sensors, or NDIR sensors. The outputs of the first gas sensor 51 and the second gas sensor 52 are input to the control device 6 periodically (for example, every minute), and time-series data of the output voltages of the first gas sensor 51 and the second gas sensor 52 are stored in the storage unit 61. The other configurations of the refrigeration cycle apparatus 100B are the same as those of the first embodiment.

[0061] The output voltage patterns of the first gas sensor 51 and the second gas sensor 52 differ depending on whether a refrigerant leaks or is sprayed. FIG. 12 is a graph showing the time changes in the output voltage of the first gas sensor 51 and the output voltage of the second gas sensor 52 during a refrigerant leak. FIG. 13 is a graph showing the time changes in the output voltage of the first gas sensor 51 and the output voltage of the second gas sensor 52 during spray ejection. In FIGS. 12 and 13, the horizontal axis represents time, and the vertical axis represents the output voltage [V] of the first gas sensor 51 and the second gas sensor 52. In addition, in FIGS. 12 and 13, the output voltage of the first gas sensor 51 is shown by a solid line, and the output voltage of the second gas sensor 52 is shown by a dashed line.

[0062] 12, in the case of a refrigerant leak, the output voltage of the second gas sensor 52 disposed near the flare section 4, which is known to be a location where refrigerant is likely to leak, rises first, followed by a rise in the output voltage of the first gas sensor 51 located away from the flare section 4. In contrast, in the case of a spray injection, the sprayed gas is sucked in through the inlet 11 of the housing 1, passes through the indoor heat exchanger 2 and the indoor fan 3, and is blown out from the outlet 12. Therefore, as shown in FIG. 13, the output voltage of the first gas sensor 51 disposed near the indoor fan 3 rises first, followed by a rise in the output voltage of the second gas sensor 52 located away from the indoor fan 3.

[0063] Therefore, in the refrigerant leakage detection process, the determination unit 62 of the control device 6 of this embodiment determines whether there is a refrigerant leakage or a spray injection by comparing patterns obtained from the time-series data of the output voltages of the first gas sensor 51 and the second gas sensor 52. The patterns described here are shapes obtained when the time-series data of the output voltages of the first gas sensor 51 and the second gas sensor 52 are respectively represented as graphs.

[0064] 14 is a flowchart showing the flow of refrigerant leakage detection processing in the fourth embodiment. The determination unit 62 of the control device 6 determines whether the output voltage of either the first gas sensor 51 or the second gas sensor 52 is greater than the first threshold value (S301). If the output voltages of both the first gas sensor 51 and the second gas sensor 52 are equal to or less than the first threshold value (S301: NO), the process returns to step S301. If the output voltage of either the first gas sensor 51 or the second gas sensor 52 is greater than the first threshold value (S301: YES), the control unit 64 determines that the alarm level is L1 (S302). At the alarm level L1, the control unit 64 does not implement any refrigerant leakage countermeasures. Alternatively, at the alarm level L1, a minor countermeasure may be implemented, such as displaying a warning on the operation display unit 131 of the remote controller 13 that there is a possibility of refrigerant leakage.

[0065] Then, the determination unit 62 compares the pattern of the output voltage of the first gas sensor 51 with the pattern of the output voltage of the second gas sensor 52 to determine whether the output voltage of the second gas sensor 52 has become greater than the first threshold value (S303). If the output voltage of the second gas sensor 52 has become greater than the first threshold value (S303: YES), the determination unit 62 determines that the alarm level is L2 (S304).

[0066] The warning level L2 is a level that occurs when a refrigerant leak occurs. If the output voltage of the second gas sensor 52 is greater than the first threshold, it is highly likely that a refrigerant leak state is occurring, as shown in FIG. 12. Therefore, in this case, the control device 6 determines that the warning level is L2, and takes measures to prevent the refrigerant leak (S305). Specifically, the control unit 64 causes the remote control 13 to display or sound a warning to notify the user of the refrigerant leak, and starts operating the indoor fan 3, or increases the airflow rate.

[0067] On the other hand, if the output voltage of the second gas sensor 52 is not greater than the first threshold (S303: NO), i.e., if the output voltage of the first gas sensor 51 is greater than the first threshold, the determination unit 62 determines whether the output voltage of the first gas sensor 51 is greater than the first threshold (S306: YES). If the output voltage of the first gas sensor 51 is greater than the first threshold (S306: YES), the process returns to step S306 and maintains the alarm level L1. On the other hand, if the output voltage of the first gas sensor 51 is equal to or less than the first threshold (S306: NO), the alarm is canceled (S307) and the process ends. That is, if the output voltage of the first gas sensor 51 is greater than the first threshold, the determination unit 62 determines that the spray injection shown in FIG. 13 has occurred, and cancels the alarm as it is not necessary to notify the user.

[0068] As described above, the refrigeration cycle apparatus 100 of this embodiment determines whether there is a refrigerant leak or a spray based on the time-series data of the output voltages of the two gas sensors and the pattern determined from the time-series data. This reduces false detections due to the sudden generation of gas other than the refrigerant gas, such as a spray.

[0069] The arrangement of the first gas sensor 51 and the second gas sensor 52 in the fourth embodiment is not limited to the example shown in Fig. 11. For example, the first gas sensor 51 may be arranged in the stagnation portion 15. Alternatively, the first gas sensor 51 may be provided outside the housing 1 to directly detect the gas emitted by the spray injection.

[0070] Although the above is a description of the embodiments, the present disclosure is not limited to the above embodiments and can be modified and combined in various ways without departing from the spirit of the present disclosure. For example, in the above embodiments, the control device 6 of the refrigeration cycle apparatus 100 is configured to perform the refrigerant leak detection process as a refrigerant leak detection device, but the refrigerant leak detection process may be performed in a refrigerant leak detection device provided separately from the refrigeration cycle apparatus 100. In this case, the refrigerant leak detection device wirelessly communicates with the gas sensor 5 and control device 6 of the refrigeration cycle apparatus 100, receives the output voltage of the gas sensor 5, and instructs the control device 6 to implement measures to prevent refrigerant leakage.

[0071] Furthermore, the determination unit 62 may perform the refrigerant leak detection process using AI (artificial intelligence). For example, the determination unit 62 may use time-series data of the output voltage of the gas sensor 5 or a pattern determined from the time-series data as input data, and determine the presence or absence of a refrigerant leak using a trained model that outputs a refrigerant leak determination result. Furthermore, in the third embodiment, the threshold correction unit 66 may use environmental information as input data, and correct each threshold using a trained model that outputs each threshold. Furthermore, in the fourth embodiment, the determination unit 62 may use time-series data of the output voltages of the first gas sensor 51 and the second gas sensor 52 or a pattern determined from the time-series data as input data, and determine the presence or absence of a refrigerant leak using a trained model that outputs a refrigerant leak determination result.

[0072] Furthermore, the content of the refrigerant leak detection process is not limited to the example of the above embodiment. For example, in the refrigerant leak detection process, when the refrigerant leak is judged to be at the warning level L1, refrigerant leak countermeasures may be implemented, and when the refrigerant leak is subsequently judged to be a spray injection, the refrigerant leak countermeasures may be terminated (the issuance of the warning may be stopped). [Explanation of symbols]

[0073] 1 Housing, 2 Indoor heat exchanger, 3 Indoor fan, 4 Flare section, 5 Gas sensor, 6, 6A Control device, 8 Spray, 11 Intake port, 12 Outlet, 13 Remote control, 15 Stagnation section, 41 Indoor piping, 42 Indoor piping, 43 Extension piping, 44 Extension piping, 51 First gas sensor, 52 Second gas sensor, 61 Memory section, 62 Determination section, 63 Timing section, 64 Control section, 65 Information acquisition section, 66 Threshold correction section, 100, 100A, 100B Refrigeration cycle device, 131 Operation display section.

Claims

1. a storage unit that stores time-series data of the output of a gas sensor that detects gas; a control device that obtains an output pattern of the gas sensor from the time-series data stored in the storage unit and determines whether or not a refrigerant leak has occurred based on the output pattern; The control device determining an index including at least one of a second derivative value, a peak value, a half width, and a sharpness from the time-series data stored in the storage unit; A refrigerant leak detection device that determines whether or not a refrigerant leak has occurred by comparing the index with a preset threshold value.

2. The control device If the current output of the gas sensor is greater than a first threshold value and the indicator is equal to or greater than a second threshold value, it is determined that a refrigerant leak has occurred; 2. The refrigerant leak detection device according to claim 1, wherein when the current output of the gas sensor is greater than the first threshold value and the index is less than the second threshold value, it is determined that no refrigerant leak has occurred.

3. The control device If the second derivative value is greater than a third threshold value and the first derivative value calculated from the time-series data stored in the storage unit is greater than a fourth threshold value, it is determined that a refrigerant leak has occurred; 2. The refrigerant leak detection device according to claim 1, wherein if the second differential value is greater than the third threshold value, the first differential value is equal to or less than the fourth threshold value, and the sharpness is less than the second threshold value, it is determined that no refrigerant leak has occurred.

4. The control device acquiring environmental information including at least one of a volume, a wind speed distribution, a ventilation rate, and a temperature and humidity of the indoor space in which the gas sensor is disposed; The refrigerant leakage detection device according to any one of claims 1 to 3, wherein the threshold value is corrected using the environmental information.

5. The refrigerant leakage detection device according to any one of claims 1 to 3, the gas sensor; an indoor heat exchanger that constitutes a refrigerant circuit; an indoor fan that sends air to the indoor heat exchanger; a warning device that issues a warning when the refrigerant leakage detection device determines that a refrigerant leak has occurred.

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