Refrigeration device, refrigerant leak detection device, and refrigerant leak detection method

Abstract

To grasp performance degradation of a refrigerant sensor.SOLUTION: A refrigerating device comprises a refrigerant circuit (11) in which a refrigerant is circulated, a first sensor (51) for detecting the refrigerant in an object space (43), and a second sensor (52) arranged in the same object space (43) as the first sensor (51), and for detecting predetermined gas. When the first sensor (51) does not detect the refrigerant due to degradation associated with use of the first sensor (51) and the second sensor (52) in a predetermined period, the second sensor (52) detects the predetermined gas even if the predetermined gas does not exist.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present disclosure relates to a refrigeration apparatus, a refrigerant leak detection device, and a refrigerant leak detection method. [Background technology]

[0002] Patent Document 1 discloses an air conditioner equipped with two refrigerant sensors. In this air conditioner, each refrigerant sensor is repeatedly switched between energized and de-energized in an alternating manner, allowing the refrigerant to be constantly detected. By providing a period during which the refrigerant sensors are de-energized, degradation of the performance of the refrigerant sensors due to energization is suppressed. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2017-180927 A Summary of the Invention [Problem to be solved by the invention]

[0004] In an air conditioner such as that disclosed in Patent Document 1, even if it is possible to suppress deterioration in performance of the refrigerant sensor, it is not possible to grasp the extent to which the performance of the refrigerant sensor has deteriorated.

[0005] An object of the present disclosure is to grasp the performance degradation of a refrigerant sensor. [Means for solving the problem]

[0006] A first aspect of the present disclosure is a refrigerant circuit (11) through which a refrigerant circulates; a first sensor (51) for detecting a refrigerant in the target space (43); a second sensor (52) arranged in the same target space (43) as the first sensor (51) and configured to detect a predetermined gas; When the first sensor (51) does not detect a refrigerant due to deterioration of the first sensor (51) and the second sensor (52) caused by use for a predetermined period of time, the second sensor (52) detects the specified gas even in a state in which the specified gas is not present. The refrigeration device is characterized by the above.

[0007] In the first aspect, some gas sensors become sensitive enough to react to even a small amount of gas due to performance degradation caused by use for a predetermined period of time, and then do not react (become less sensitive) even when exposed to a high concentration gas. A second sensor (52) whose performance deteriorates faster than the first sensor (51), or a second sensor (52) whose performance deteriorates at the same rate and detects a predetermined gas at a lower concentration than the concentration detected by the first sensor (51), is disposed in the same target space as the first sensor (51). As the sensitivity of the first sensor (51) and the second sensor (52) increases with performance deterioration, the second sensor (52) reacts before the first sensor (51) even when there is no gas in the target space (43). In this way, when the first sensor (51) does not detect, the second sensor (52) detects, and thus it is possible to know that the performance of the first sensor (51) has deteriorated in the same way as the second sensor (52). Furthermore, by checking the deterioration in performance of the second sensor (52), it is possible to replace the first sensor (51) before the deterioration in performance of the first sensor (51) progresses to a critical level.

[0008] The second aspect is the first aspect, the predetermined gas is a refrigerant, The second sensor (52) detects the refrigerant in the target space (43).

[0009] In the second embodiment, the first sensor (51) and the second sensor (52) both detect the refrigerant in the target space (43).

[0010] The third aspect is the first or second aspect, The first sensor (51) detects a refrigerant having a first concentration, The second sensor (52) detects the predetermined gas at a concentration lower than the first concentration.

[0011] In the third aspect, due to deterioration of the first sensor (51) and the second sensor (52) with use, the sensor sensitivity of the second sensor (52) becomes sharper earlier than that of the first sensor (51), which makes it possible to grasp the deterioration of the first sensor (51).

[0012] The fourth aspect is the first or second aspect, The first sensor (51) detects a refrigerant having a first concentration, the second sensor (52) detects the predetermined gas at a concentration equal to the first concentration; The second sensor (52) deteriorates faster with use over a given period of time than the first sensor (51).

[0013] In the fourth aspect, since the deterioration rate of the second sensor (52) is faster than that of the first sensor (51), the sensor sensitivity of the second sensor (52) becomes sharper than that of the first sensor (51), which makes it possible to grasp the deterioration of the first sensor (51).

[0014] A fifth aspect is any one of the first to fourth aspects, The control unit (C2) determines whether or not a first condition is satisfied, that is, the first sensor (51) does not detect a refrigerant and the second sensor (52) detects the predetermined gas.

[0015] In the fifth aspect, the control section (C2) determines whether the first condition is satisfied, and thereby it is possible to know that the first sensor (51) is deteriorating.

[0016] The sixth aspect is the fifth aspect, The control unit (C2) determines, as the first condition, that a condition that the first sensor (51) does not detect a refrigerant and the second sensor (52) detects the specified gas continues for a specified period of time.

[0017] In the sixth aspect, by determining whether the first condition is satisfied, it is possible to determine whether refrigerant is actually leaking or whether the first sensor (51) is degraded, thereby making it possible to prevent erroneous detection of degradation in performance of the first sensor (51).

[0018] The seventh aspect is the fifth or sixth aspect, The device further includes an alarm unit (42) that notifies a person that the first sensor (51) has deteriorated when the first condition is satisfied.

[0019] In the seventh aspect, the notification section (42) notifies the user, thereby making it possible to reduce delay in discovering the performance degradation of the first sensor (51).

[0020] The eighth aspect is any one of the first to seventh aspects, An indoor unit (30) that conditions air in a space to be air-conditioned, The first sensor (51) and the second sensor (52) are disposed inside the indoor unit (30).

[0021] In the eighth aspect, refrigerant leakage inside the indoor unit (30) can be detected.

[0022] The ninth aspect is a first sensor (51) for detecting a refrigerant in the target space (43); a second sensor (52) arranged in the same target space (43) as the first sensor (51) and configured to detect a predetermined gas; When the first sensor (51) does not detect a refrigerant due to deterioration of the first sensor (51) and the second sensor (52) caused by use for a predetermined period of time, the second sensor (52) detects the specified gas even in a state in which the specified gas is not present. The refrigerant leak detection device is characterized by the above.

[0023] A tenth aspect is a first sensor (51) for detecting a refrigerant in the target space (43); a second sensor (52) arranged in the same target space (43) as the first sensor (51) and configured to detect a predetermined gas; When the first sensor (51) does not detect a refrigerant due to deterioration of the first sensor (51) and the second sensor (52) caused by use for a predetermined period of time, the second sensor (52) detects the predetermined gas even in the absence of the predetermined gas. The present invention relates to a refrigerant leakage detection method. [Brief description of the drawings]

[0024] [Figure 1] FIG. 1 is a piping diagram of an air conditioner according to an embodiment. [Diagram 2] FIG. 2 is a block diagram showing the relationship between the air conditioner control device and each device. [Diagram 3] FIG. 3 is a diagram showing the configuration of an indoor unit of the air conditioner. [Figure 4] FIG. 4 is a graph showing a schematic diagram of the characteristics of the refrigerant sensor. [Diagram 5] FIG. 5 is a diagram for explaining a method for detecting deterioration of the refrigerant sensor. [Figure 6] FIG. 6 is a flowchart showing the control of refrigerant leakage detection. [Figure 7] FIG. 7 is a diagram for explaining a method for detecting deterioration of the refrigerant sensor according to the first modification. [Figure 8] FIG. 8 is a diagram for explaining a method for detecting deterioration of a refrigerant sensor according to the second modification. [Figure 9] FIG. 9 is a flowchart showing the control of refrigerant leakage detection. [Figure 10] FIG. 10 is a block diagram showing the configuration of a refrigerant leakage detection device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the following embodiments are essentially preferred examples, and are not intended to limit the scope of the present invention, its applications, or its uses. Furthermore, each configuration of the embodiments, modifications, other examples, etc. described below can be combined or partially substituted within the scope in which the present invention can be implemented.

[0026] (1) Overall configuration of air conditioning system 1 to 3, an air conditioner (10) adjusts the temperature of air in an indoor space (S) of a building or the like. The air conditioner (10) is an example of a refrigeration unit (10) of the present disclosure. The indoor space (S) is an example of a space to be air conditioned (S) of the present disclosure.

[0027] The air conditioner (10) cools and heats an indoor space (S). The air conditioner (10) is a multi-type air conditioner having a plurality of indoor units (30). The air conditioner (10) has an outdoor unit (20), a plurality of indoor units (30), communication piping (12), and a control device (AC). The plurality of indoor units (30) and the outdoor unit (20) are connected to each other via the communication piping (12). This connection forms a refrigerant circuit (11), which is a closed circuit.

[0028] (2-1) Refrigerant circuit The refrigerant circuit (11) includes an outdoor circuit (20a) provided in the outdoor unit (20) and an indoor circuit (30a) provided in each of the indoor units (30).

[0029] The refrigerant circuit (11) is filled with a slightly flammable refrigerant. In this example, the slightly flammable refrigerant is R32 (difluoromethane). R32 has a relatively low GWP (Global Warming Potential), but is slightly flammable. Therefore, if the refrigerant leaks into the indoor space (S) and the refrigerant concentration in the indoor space (S) increases, the refrigerant may burn. The density of the refrigerant is greater than the density of air. Therefore, if the refrigerant leaks into the indoor space (S), the refrigerant flows to the lower part of the indoor space (S).

[0030] (2-2) Connecting piping The connection pipe (12) includes a liquid connection pipe (13) and a gas connection pipe (14).

[0031] The liquid connection pipe (13) includes a first main pipe (13a) and a plurality of first branch pipes (13b) branching off from the first main pipe (13a). One end of the first main pipe (13a) is connected to the outdoor circuit (20a) via a first shut-off valve (15) which is a liquid shut-off valve. One end of each of the plurality of first branch pipes (13b) is connected to the first main pipe (13a). The other end of each of the plurality of first branch pipes (13b) is connected to a corresponding indoor circuit (30a).

[0032] The gas connection pipe (14) includes a second main pipe (14a) and a plurality of second branch pipes (14b) branching off from the second main pipe (14a). One end of the second main pipe (14a) is connected to the outdoor unit (20) via a second shutoff valve (16) which is a gas shutoff valve. One end of each of the plurality of second branch pipes (14b) is connected to the second main pipe (14a). The other end of each of the plurality of second branch pipes (14b) is connected to a corresponding indoor unit (30).

[0033] (2-3) Outdoor unit The outdoor unit (20) is disposed outdoors, for example, on the roof of a building or on the ground.

[0034] The outdoor unit (20) includes a compressor (21), an outdoor heat exchanger (22), an outdoor fan (23), a switching mechanism (24), an outdoor expansion valve (25), and a first control device (C1).

[0035] The compressor (21) compresses the sucked refrigerant. The compressor (21) discharges the compressed refrigerant. The compressor (21) is a rotary compressor such as a scroll type, a swing piston type, a rolling piston type, or a screw type. The compressor (21) is configured such that the operating frequency (rotation speed) is variable by an inverter device.

[0036] The outdoor heat exchanger (22) is a fin-and-tube air heat exchanger that exchanges heat between the refrigerant flowing therethrough and the outdoor air.

[0037] The outdoor fan (23) is disposed outdoors near the outdoor heat exchanger (22). In this embodiment, the outdoor fan (23) is a propeller fan. The outdoor fan (23) delivers air passing through the outdoor heat exchanger (22).

[0038] The switching mechanism (24) changes the flow path of the refrigerant circuit (11) so as to switch between a first refrigeration cycle, which is a cooling cycle, and a second refrigeration cycle, which is a heating cycle. The switching mechanism (24) is a four-way switching valve. The switching mechanism (24) has a first port, a second port, a third port, and a fourth port. The first port of the switching mechanism (24) is connected to the discharge portion of the compressor (21). The second port of the switching mechanism (24) is connected to the suction portion of the compressor (21). The third port of the switching mechanism (24) is connected to the gas connection pipe (14) via the second stop valve (16). The fourth port of the switching mechanism (24) is connected to the gas end of the outdoor heat exchanger (22).

[0039] The switching mechanism (24) is switchable between a first state and a second state. In the first state (shown by a solid line in FIG. 1), the switching mechanism (24) connects the first port to the fourth port and connects the second port to the third port. In the second state (shown by a dashed line in FIG. 1), the switching mechanism (24) connects the first port to the third port and connects the second port to the fourth port.

[0040] The outdoor expansion valve (25) reduces the pressure of the refrigerant. The outdoor expansion valve (25) is disposed in the outdoor circuit (20a) between the first stop valve (15) and the outdoor heat exchanger (22). The outdoor expansion valve (25) is an electronic expansion valve whose opening degree is adjustable.

[0041] (2-4) Indoor unit As shown in Fig. 3, the indoor unit (30) of this example is of a ceiling-embedded type. The indoor unit (30) includes a casing (34), an indoor fan (33), an indoor heat exchanger (32), a bell-mouth (49), a drain pan (44), and a flap (38). The indoor unit (30) conditions the room space (S).

[0042] The casing (34) has a casing body (35) and a panel (36). The casing body (35) is formed in a rectangular box shape with an open surface formed on the lower side. The panel (36) is detachably attached to the open surface of the casing body (35). The panel (36) has a panel body (37) having a rectangular frame shape in a plan view, and an intake grill (45) provided in the center of the panel body (37). An intake port (46) is formed in the center of the panel body (37). The intake grill (45) is attached to the intake port (46). An exhaust port (47) is formed in each of the four side edges of the panel body (37). An air passage (48) is formed inside the casing (34) between the intake port (46) and the exhaust port (47).

[0043] The indoor fan (33) is disposed in the air passage (48) upstream of the indoor heat exchanger (32). The indoor fan (33) is of a centrifugal type. The indoor fan (33) supplies air passing through the indoor heat exchanger (32) to the indoor space (S). The indoor fan (33) is configured so that its airflow rate can be switched between a plurality of levels.

[0044] The indoor heat exchanger (32) is disposed in the air passage (48). The indoor heat exchanger (32) is disposed around the indoor fan (33). In the indoor heat exchanger (32), heat is exchanged between the air transported by the indoor fan (33) and the refrigerant.

[0045] The bellmouth (49) is disposed in the air passage (48). Specifically, the bellmouth (49) is disposed above the suction port (46). The bellmouth (49) straightens the flow of the suction air.

[0046] The drain pan (44) is disposed in the air passage (48). Specifically, the drain pan (44) is disposed above the bell mouth (49) and below the indoor heat exchanger (32). The drain pan (44) is formed in a concave shape. Water generated when the indoor heat exchanger (32) functions as an evaporator is stored in the drain pan (44). The water stored in the drain pan (44) is discharged to the outside via a drain pipe (not shown).

[0047] The flap (38) adjusts the direction of the outlet air that is blown out from the air outlet (47). The flap (38) is provided along the side edge of the panel body (37) or along the longitudinal direction of the air outlet (47).

[0048] The indoor unit (30) has a second control device (C2). The second control device (C2) of each indoor unit (30) and the first control device (C1) are connected to each other via a first communication line (W1). The first communication line (W1) is wired or wireless.

[0049] (2-5) Remote Controller The air conditioner (10) has a remote controller (40). One remote controller (40) is provided for each indoor unit (30). The remote controller (40) is a device for operating the air conditioner (10). As shown in FIG. 2, the remote controller (40) has a first operation unit (41) and a first display unit (42) as functional units. Note that the term "functional unit" used here or described below includes a functional unit realized only by hardware, a functional unit realized only by software, and a functional unit realized by a combination of hardware and software.

[0050] The first operation unit (41) is a functional unit that enables a person to input various instructions to the air conditioner (10). The first operation unit (41) includes a switch, a button, or a touch panel.

[0051] The first display unit (42) is a functional unit that displays settings for the air conditioning apparatus (10) and the status of the air conditioning apparatus (10). The first display unit (42) includes a display. The first display unit (42) is an example of the notification unit (42) of the present disclosure.

[0052] The remote controller (40) includes a third control device (C3). The third control device (C3) and the second control device (C2) are connected to each other via a second communication line (W2). The second communication line (W2) is wired or wireless.

[0053] (2-6) First sensor and second sensor The air conditioner (10) of this embodiment includes a first sensor (51) and a second sensor (52). The first sensor (51) and the second sensor (52) are arranged in the same partitioned space inside the indoor unit (30). The first sensor (51) and the second sensor (52) are arranged close to each other. The first sensor (51) and the second sensor (52) detect a refrigerant. The refrigerant is an example of a predetermined gas in the present disclosure. Hereinafter, the first sensor (51) and the second sensor (52) may be collectively referred to simply as the refrigerant sensors (51, 52).

[0054] Specifically, the first sensor (51) and the second sensor (52) of this embodiment are disposed in a first space (43) which is a space inside the drain pan (44). The first space (43) is an example of a target space (43) in this example. In this manner, the second sensor (52) is disposed in the same first space (43) as the first sensor (51). The first sensor (51) and the second sensor (52) detect the refrigerant in the first space (43).

[0055] Since the first space (43) has a concave shape, the refrigerant, which has a density greater than that of air, tends to accumulate in the first space (43). Therefore, the first sensor (51) in the first space (43) can relatively easily detect refrigerant leaking into the indoor unit (30).

[0056] The refrigerant sensors (51, 52) are semiconductor sensors. The refrigerant sensors (51, 52) output a detection signal with a greater intensity (e.g., a current value) as the concentration of the leaked refrigerant increases. For example, the refrigerant sensors (51, 52) include tin oxide, a ceramic substrate such as alumina, and a heater.

[0057] When the refrigerant sensors (51, 52) are energized, they are able to detect refrigerant gas. Specifically, when the heaters of the refrigerant sensors (51, 52) are energized, the tin oxide is heated via the ceramic substrate. When the tin oxide is heated to a predetermined temperature, the refrigerant sensors (51, 52) are able to detect the refrigerant. The refrigerant sensors (51, 52) transmit detection signals corresponding to the concentration of the refrigerant in contact with the refrigerant sensors (51, 52) to the second control device (C2).

[0058] The first sensor (51) detects a refrigerant of a first concentration. The first concentration is, for example, 5,000 ppm. Specifically, when a detection signal transmitted from the first sensor (51) to the second control device (C2) indicates 5,000 rpm, a notification device (60) described below is activated. The second sensor (52) detects a refrigerant of a second concentration. The second concentration is lower than the first concentration. The second concentration is, for example, 3,000 rpm. Specifically, the second sensor (52) transmits a detection signal indicating 3,000 rpm to the second control device (C2).

[0059] The first sensor (51) is connected to the second control device (C2) of the indoor unit (30) through a third communication line (W3). The third communication line (W3) is wired or wireless. A detection signal output from the first sensor (51) is input to the second control device (C2) through the third communication line (W3).

[0060] The second sensor (52) is connected to the second control device (C2) of the indoor unit (30) through a fourth communication line (W4). The fourth communication line (W4) is wired or wireless. A detection signal output from the second sensor (52) is input to the second control device (C2) through the fourth communication line (W4).

[0061] (2-7) Notification device The air conditioner (10) includes an alarm device (60). The alarm device (60) is provided in the indoor unit (30). The alarm device (60) is a device that notifies a person of a refrigerant leak. Specifically, the alarm device (60) notifies a user in the indoor space (S) that the first sensor (51) has detected a first concentration.

[0062] The notification device (60) has a light-emitting unit (61) and a sound-emitting unit (62) that function as an alarm. The light-emitting unit (61) notifies a person of a refrigerant leakage by light. The light-emitting unit (61) is, for example, an LED. The sound-emitting unit (62) notifies a person of a refrigerant leakage by sound. The sound-emitting unit (62) is, for example, a speaker.

[0063] The notification device (60) has a fourth control device (C4). The fourth control device (C4) is connected to the second control device (C2) of the indoor unit (30) via a fifth communication line (W5). The fifth communication line (W5) is wired or wireless.

[0064] The alarm device (60) is activated upon receiving an alarm signal transmitted from the second control device (C2). The alarm signal is transmitted when the second control device (C2) receives a detection signal transmitted from the first sensor (51). When the alarm device (60) is activated, the light-emitting unit (61) emits light and the sound generating unit (62) generates an alarm sound.

[0065] (2-8) Control device The control device (AC) controls the operation of the air conditioner (10). The control device (AC) includes a first control device (C1), a second control device (C2), a third control device (C3), a fourth control device (C4), a first communication line (W1), a second communication line (W2), a third communication line (W3), a fourth communication line (W4), and a fifth communication line (W5). Each of the first control device (C1), the second control device (C2), the third control device (C3), and the fourth control device (C4) includes an MCU (Micro Control Unit), an electric circuit, and an electronic circuit. The MCU includes a CPU (Central Processing Unit), a memory, and a communication interface. The memory stores various programs to be executed by the CPU.

[0066] The first control device (C1) controls the compressor (21), the switching mechanism (24), the outdoor expansion valve (25), and the outdoor fan (23).

[0067] The second control device (C2) is the control unit (C2) of the present disclosure. The second control device (C2) controls the indoor expansion valve (31) and the indoor fan (33). The second control device (C2) receives detection signals from the refrigerant sensors (51, 52). The second control device (C2) determines whether the detection signals from the refrigerant sensors (51, 52) are signals indicating a first concentration or higher. When the second control device (C2) determines that the detection signals from the refrigerant sensors (51, 52) are signals indicating the first concentration, it transmits a notification signal to the fourth control device (C4).

[0068] The third control device (C3) outputs to the second control device (C2) an instruction based on an input from the first operation unit (41). The third control device (C3) causes the first display unit (42) to display predetermined information in response to the input from the first operation unit (41).

[0069] The fourth control device (C4) controls the notification device (60). Specifically, when a notification signal output from the second control device (C2) is input to the fourth control device (C4), the fourth control device (C4) activates the light-emitting unit (61) and the sound-generating unit (62).

[0070] (3) Driving behavior The operation of the air conditioner (10) will be described with reference to Fig. 1. The air conditioner (10) switches between cooling operation and heating operation. In Fig. 1, the flow of refrigerant during cooling operation is indicated by solid arrows, and the flow of refrigerant during heating operation is indicated by dashed arrows.

[0071] (3-1) Cooling operation In the cooling operation, the first control device (C1) operates the compressor (21) and the outdoor fan (23), sets the switching mechanism (24) to the first state, and fully opens the outdoor expansion valve (25). The second control device (C2) operates the indoor fan (33) and adjusts the indoor expansion valve (31) to a predetermined opening degree.

[0072] In the cooling operation, the refrigerant circuit (11) performs a first refrigeration cycle. In the first refrigeration cycle, the outdoor heat exchanger (22) functions as a radiator (strictly speaking, a condenser), and the indoor heat exchanger (32) functions as an evaporator.

[0073] Specifically, the refrigerant compressed by the compressor (21) flows through the outdoor heat exchanger (22). In the outdoor heat exchanger (22), the refrigerant dissipates heat to the outdoor air and is condensed. The refrigerant condensed in the outdoor heat exchanger (22) flows through the liquid connection pipe (13) and is divided into each indoor circuit (30a). In each indoor circuit (30a), the refrigerant is reduced in pressure by the indoor expansion valve (31) and then flows through the indoor heat exchanger (32). In the indoor heat exchanger (32), the refrigerant absorbs heat from the indoor air and evaporates. The refrigerant evaporated in each indoor heat exchanger (32) joins together in the gas connection pipe (14) and is then drawn into the compressor (21).

[0074] (3-2) Heating operation In the heating operation, the first control device (C1) operates the compressor (21) and the outdoor fan (23), sets the switching mechanism (24) to the second state, and adjusts the outdoor expansion valve (25) to a predetermined opening degree. The second control device (C2) operates the indoor fan (33) and adjusts the indoor expansion valve (31) to a predetermined opening degree.

[0075] In the heating operation, the refrigerant circuit (11) performs a second refrigeration cycle. In the second refrigeration cycle, the indoor heat exchanger (32) functions as a radiator (strictly speaking, a condenser), and the outdoor heat exchanger (22) functions as an evaporator.

[0076] Specifically, the refrigerant compressed by the compressor (21) flows through the gas connection pipe (14) and is divided into each indoor circuit (30a). In each indoor circuit (30a), the refrigerant flows through the indoor heat exchanger (32). In the indoor heat exchanger (32), the refrigerant dissipates heat to the indoor air and condenses. The refrigerant condensed in each indoor heat exchanger (32) is reduced in pressure by each indoor expansion valve (31) and then merges in the liquid connection pipe (13). The refrigerant in the liquid connection pipe (13) is reduced in pressure by the outdoor expansion valve (25) and then flows through the outdoor heat exchanger (22). In the outdoor heat exchanger (22), the refrigerant absorbs heat from the outdoor air and evaporates. The refrigerant evaporated in the outdoor heat exchanger (22) is sucked into the compressor (21).

[0077] (4) Issues related to performance degradation of refrigerant sensors Semiconductor-type refrigerant sensors are relatively accurate and inexpensive, making them suitable for installation in air conditioners such as those in this embodiment. However, the sensitivity of the refrigerant sensor to detect the refrigerant gradually decreases due to the influence of gases such as siloxane floating around the refrigerant sensor. This makes it necessary to repair or replace the refrigerant sensor before the performance of the refrigerant sensor deteriorates. However, when the refrigerant sensor does not detect the refrigerant, it is difficult to determine whether the sensor is unable to detect the refrigerant due to a decrease in sensitivity or whether the sensor is unable to detect the refrigerant because there is no refrigerant around the refrigerant sensor in the first place. Thus, it is not easy to grasp the degree of deterioration in the performance of the refrigerant.

[0078] In response to this, a method of setting the life span of the refrigerant sensor is considered. Specifically, the period during which the accuracy of the refrigerant sensor in detecting the refrigerant is estimated to fall below a reference value when the sensor is used continuously in a normal environment is set as the life span. Then, when the life span has elapsed, the refrigerant sensor is repaired or replaced. However, since the progress of performance degradation of the refrigerant sensor varies depending on the air environment around the refrigerant sensor, the performance of the refrigerant sensor may have deteriorated before the set life span has elapsed. In addition, the performance of the refrigerant sensor may not have deteriorated even after the set life span has elapsed, and in such a case, repairing or replacing the refrigerant sensor is not preferable in terms of cost. Therefore, with such a method, it cannot be said with certainty that the refrigerant sensor can be repaired or replaced before the performance degradation progresses.

[0079] Another possible method is to place two sensors to detect the amount of leaked refrigerant. Specifically, by placing such sensors close to each other, if the values ​​detected by the two sensors do not match, it is determined that the performance of the refrigerant sensor has deteriorated. However, since it is not possible to determine which value is accurate when the values ​​detected by the two sensors do not match, it cannot be said that this method is sufficient to grasp the deterioration of the performance of the refrigerant sensor.

[0080] It is known that the performance of semiconductor-type refrigerant sensors deteriorates in two stages. Specifically, as shown in Figure 4, in stage 1 (the period up to T1), the response of the refrigerant sensor becomes more sensitive.

[0081] "Sensitization" is a phenomenon in which the refrigerant sensor detects a refrigerant concentration that is lower than the target concentration that it should detect. For example, when the target concentration is 5,000 ppm, the refrigerant sensor will detect the actual refrigerant concentration as 5,000 ppm even if the actual refrigerant concentration is 3,000 ppm due to the sensitivity of the refrigerant sensor. If the sensitivity increases further, the refrigerant sensor will detect the actual refrigerant concentration as 5,000 ppm even if the actual refrigerant concentration is 1,000 ppm. In this case, even if the actual refrigerant concentration is 1,000 rpm, the refrigerant sensor will output a detection signal for 5,000 rpm, causing the alarm device (60) to operate.

[0082] As the sensitivity of the refrigerant sensor increases in this way, the refrigerant sensor will be able to detect even trace amounts of refrigerant as the target concentration, and eventually, even when there is no refrigerant present (the refrigerant concentration becomes zero), the refrigerant sensor will detect the refrigerant as the target concentration.

[0083] Then, in stage 2 (after T1), the response of the refrigerant sensor slows down. "Slowing" is a phenomenon in which the refrigerant sensor does not detect the actual refrigerant concentration even when it is equal to or greater than the target concentration. When the refrigerant sensor slows down, the refrigerant sensor no longer responds even when exposed to a relatively high concentration of refrigerant.

[0084] The air conditioner (10) of this embodiment is configured to take advantage of the properties of such a semiconductor-type refrigerant sensor so as to enable relatively rapid detection of performance degradation of the first sensor (51). A method for detecting performance degradation of the refrigerant sensor of this embodiment will now be described.

[0085] (5) Method for detecting deterioration of refrigerant sensor performance In the method for detecting performance deterioration of a refrigerant sensor of this embodiment, the second control device (C2) simultaneously energizes and de-energizes the first sensor (51) and the second sensor (52). The second control device (C2) may constantly energize the first sensor (51) and the second sensor (52) regardless of whether the air conditioner (10) is in the ON state or the OFF state.

[0086] As shown in Fig. 5, the first sensor (51) becomes sensitive after a predetermined period of use. Specifically, the first sensor (51) detects the refrigerant concentration as a first concentration even if the actual refrigerant concentration in the surrounding area is lower than the first concentration. Similarly, the second sensor (52) detects the refrigerant concentration as a second concentration after a predetermined period of use even if the actual refrigerant concentration in the surrounding area is lower than the second concentration.

[0087] Here, the first sensor (51) and the second sensor (52) deteriorate at the same rate due to use, so that the first sensor (51) and the second sensor (52) become sensitive at the same pace. Since the second concentration is lower than the first concentration, if the first sensor (51) and the second sensor (52) become sensitive at the same rate, the second sensor (52) will react to the presence of refrigerant before the first sensor (51) even when there is no refrigerant. In other words, when the first sensor (51) does not detect the refrigerant, the second sensor (52) will detect the refrigerant even when there is no refrigerant. In this case, the second sensor (52) transmits a detection signal to the second control device (C2). The second control device (C2) determines that it has not received a detection signal from the first sensor (51) and has received a detection signal from the second sensor (52), and transmits the first information to the third control device (C3). The first information is information indicating that the performance degradation of the first sensor (51) is progressing. Specifically, the first information is information indicating that the sensitivity of the first sensor (51) is about to decrease (Stage 2). This makes it possible to grasp the performance degradation of the first sensor (51).

[0088] (6) Control Flow The control flow of the refrigerant leakage detection method by the air conditioner (10) of the present embodiment will be described with reference to FIG.

[0089] In step S11, the second control device (C2) energizes the first sensor (51) and the second sensor (52). The second control device (C2) may execute step S11 when the air conditioner (10) is connected to an external power supply.

[0090] In step S12, the second control device (C2) determines whether or not the first sensor (51) has detected refrigerant of the first concentration. If it is determined that the first sensor (51) has detected refrigerant of the first concentration (YES in step S12), step S13 is executed. If it is determined that the first sensor (51) has not detected refrigerant of the first concentration (YES in step S12), step S15 is executed.

[0091] In step S13, the second control device (C2) transmits a notification signal to the fourth control device (C4).

[0092] In step S14, the fourth control device (C4) activates the alarm device (60). When the alarm device (60) is activated, the light-emitting unit (61) emits light and the sound-emitting unit (62) emits an alarm sound. The alarm device (60) may continue to operate the light-emitting unit (61) and the sound-emitting unit (62) until the operation of the alarm device (60) is deactivated by a user operation. When the refrigerant concentration detected by the first sensor (51) falls below the first concentration and the alarm device (60) no longer receives an alarm signal, the alarm device (60) may stop the operation of the light-emitting unit (61) and the sound-emitting unit (62).

[0093] In step S15, the second control device (C2) determines whether or not the second sensor (52) detects refrigerant of the second concentration. If it is determined that the second sensor (52) detects refrigerant of the second concentration (YES in step S15), step S16 is executed. If it is determined that the second sensor (52) does not detect refrigerant of the second concentration (NO in step S15), step S12 is executed. Note that as the sensitivity of the second sensor (52) increases, the second sensor (52) transmits a detection signal to the second control device (C2) even if there is no refrigerant in the first space (43).

[0094] In step S16, the second control device (C2) judges whether or not a predetermined period has elapsed. If it is judged that the predetermined period has elapsed (YES in step S16), step S17 is executed. If it is judged that the predetermined period has not elapsed (NO in step S16), step S16 is executed again.

[0095] In step S17, the second control device (C2) determines whether or not the first condition is satisfied. The first condition is a condition in which the first sensor (51) does not detect refrigerant and the second sensor (52) detects refrigerant for a predetermined period of time. If it is determined that the first condition is satisfied (YES in step S17), step S18 is executed. If it is determined that the first condition is not satisfied (NO in step S17), step S12 is executed again. In this manner, by determining that the first condition is satisfied, that is, that the first sensor (51) does not detect refrigerant of the first concentration and the second sensor (52) detects refrigerant of the second concentration for a predetermined period of time, it is possible to reliably prevent the first sensor (51) from being erroneously determined to be deteriorated. Specifically, when refrigerant actually leaks into the first space (43) and the refrigerant concentration around the refrigerant sensors (51, 52) becomes equal to or greater than the second concentration and less than the first concentration, the first sensor (51) does not detect the refrigerant of the first concentration, and the second sensor (52) detects the refrigerant of the second concentration. When the refrigerant concentration further increases and reaches the first concentration after a predetermined period of time, the first sensor (51) detects the refrigerant of the first concentration. This state in which the first sensor (51) does not detect the refrigerant of the first concentration and the second sensor (52) detects the refrigerant of the second concentration can occur temporarily even when refrigerant is actually leaking. Therefore, by providing the above-mentioned predetermined period of time, it is possible to determine whether the refrigerant sensors (51, 52) are in a deteriorated state or whether refrigerant is actually leaking.

[0096] In step S18, the second control device (C2) transmits the first information to the third control device (C3).

[0097] In step S19, the third control device (C3) displays the first information on the first display unit (42). The first display unit (42) displays a message prompting the user to replace the first sensor (51). The first display unit (42) may display a message prompting the user to replace the first sensor (51) and the second sensor (52).

[0098] (7) Features (7-1) In the air conditioning apparatus (10) of this embodiment, when the first sensor (51) does not detect a refrigerant due to deterioration of the first sensor (51) and the second sensor (52) accompanying use for a specified period of time, the second sensor (52) detects a specified gas in the first space (43) (target space) even in the absence of the specified gas.

[0099] According to the present embodiment, when the first sensor (51) does not detect something, the second sensor (52) detects something, and it is possible to know that the performance of the first sensor (51) has deteriorated in the same way as the second sensor. As a result, the first sensor (51) can be replaced before the performance deterioration of the first sensor (51) progresses to a certain degree. In addition, since the first sensor (51) can be replaced according to the degree of deterioration of the performance, it is possible to prevent the performance from deteriorating before the replacement of the first sensor (51) or the first sensor (51) from being replaced even when the performance has not deteriorated, compared to a case in which a life span is set for the first sensor (51) and the first sensor (51) is replaced at the life span.

[0100] (7-2) In the air conditioner (10) of the present embodiment, the second sensor (52) detects the refrigerant in the first space (43). In this manner, the first sensor (51) and the second sensor (52) are the same type of sensor that detects the refrigerant.

[0101] (7-3) In the air conditioner (10) of this embodiment, the first sensor (51) detects refrigerant of a first concentration, and the second sensor (52) detects refrigerant of a concentration lower than the first concentration.

[0102] In this embodiment, due to the increased sensitivity of the first sensor (51) and the second sensor (52) to the refrigerant, even when the refrigerant is not present in the first space (43), the second sensor (52) detects the presence of the refrigerant earlier than the first sensor (51), thereby making it possible to grasp the deterioration of the first sensor (51).

[0103] (7-4) In the air conditioning apparatus (10) of this embodiment, the second control device (C2) (controller) determines, as a first condition, that a condition exists in which the first sensor (51) does not detect a refrigerant and the second sensor (52) detects a refrigerant for a predetermined period of time.

[0104] According to the present embodiment, by determining whether the first condition is satisfied, it is possible to determine whether refrigerant is actually leaking or whether the first sensor (51) is degraded, thereby making it possible to prevent erroneous detection of degradation in performance of the first sensor (51).

[0105] (7-5) The air conditioner (10) of the present embodiment includes a first indication section (42) (notification section) that notifies a person that the first sensor (51) has deteriorated when a first condition is met.

[0106] According to the present embodiment, the first display unit (42) of the remote controller (40) displays a message indicating that the first sensor (51) has deteriorated. This enables the user to replace the first sensor (51) before the performance of the first sensor (51) deteriorates further. If the first sensor (51) can be replaced in this manner in response to deterioration of the performance of the first sensor (51), a delay in detecting a refrigerant leak can be reliably prevented.

[0107] (7-6) The air conditioner (10) of this embodiment includes an indoor unit (30) that conditions the air in a space to be air-conditioned, and the first sensor (51) and the second sensor (52) are disposed inside the indoor unit (30). This allows the first sensor (51) to detect refrigerant leakage inside the indoor unit (30).

[0108] (8) Variations The above embodiment may be modified as follows. The following describes the differences from the embodiment.

[0109] (8-1) Variation 1 In the first modification, the second sensor (52) detects refrigerant having the same first concentration as the first sensor (51). The second sensor (52) is configured to deteriorate faster with use for a predetermined period of time than the first sensor (51).

[0110] As shown in Fig. 7, the first sensor (51) and the second sensor (52) become more sensitive to the refrigerant due to deterioration caused by use for a certain period of time. In stage 1, the performance of the second sensor (52) deteriorates faster than that of the first sensor (51). Therefore, even when the first sensor (51) does not detect any refrigerant, the second sensor (52) detects the refrigerant as if there is a refrigerant in the first space (43) even when there is no refrigerant. In this way, in this example, the performance deterioration of the first sensor can be detected before the stage moves to stage 2 (before the response of the first sensor (51) to the refrigerant becomes slow).

[0111] (8-2) Variation 2 In the second modification, the second sensor (52) detects a predetermined gas other than the refrigerant. The predetermined gas is, for example, a gas suspended in the room. The second sensor (52), like the first sensor (51), is configured to become more sensitive to the gas as it deteriorates with use for a certain period of time.

[0112] As shown in FIG. 8, the second sensor (52) detects a predetermined gas at a second concentration. The second concentration is the concentration of the predetermined gas converted into a refrigerant concentration. The second sensor (52) is configured to detect a gas at a second concentration. However, as the second sensor (52) becomes more sensitive to the predetermined gas in stage 1, the second sensor (52) detects a gas at a concentration lower than the second concentration as the second concentration. In this example, when the second control device (C2) receives a detection signal indicating that the second sensor (52) has detected a gas at a third concentration lower than the second concentration as the gas at the second concentration, the first display unit (42) displays that the performance of the first sensor (51) is deteriorating.

[0113] In this manner, also in this example, as the responses of the first sensor (51) and the second sensor (52) become more sensitive in stage 1, the second sensor (52) detects the gas of the third concentration when the first sensor (51) does not detect the refrigerant. In this way, in this example, the detection of the gas of the third concentration by the second sensor (52) indicates that the first sensor (51) is degraded.

[0114] (9) Control Flow The control flow of the refrigerant leakage detection method for the air conditioner (10) according to the second modification will be described with reference to FIG.

[0115] In step S21, the second control device (C2) energizes the first sensor (51) and the second sensor (52). The second control device (C2) may execute step S21 when the air conditioner (10) is connected to an external power supply.

[0116] In step S22, the second control device (C2) determines whether or not the first sensor (51) has detected refrigerant of the first concentration. If it is determined that the first sensor (51) has detected refrigerant of the first concentration (YES in step S22), step S23 is executed. If it is determined that the first sensor (51) has not detected refrigerant of the first concentration (YES in step S22), step S25 is executed.

[0117] In step S23, the second control device (C2) transmits a notification signal to the fourth control device (C4).

[0118] In step S24, the fourth control device (C4) activates the notification device (60). When the notification device (60) is activated, the light emitting section (61) emits light and the sound generating section (62) generates an alarm sound.

[0119] In step S25, the second control device (C2) determines whether the second sensor (52) detects the second concentration. In practice, it is determined whether the second sensor (52) detects the gas of the third concentration. If it is determined that the second sensor (52) detects the gas of the third concentration (YES in step S25), step S26 is executed. If it is determined that the second sensor (52) does not detect the gas of the third concentration (NO in step S25), step S22 is executed.

[0120] In step S26, the second control device (C2) judges whether or not a predetermined period has elapsed. If it is judged that the predetermined period has elapsed (YES in step S26), step S27 is executed. If it is judged that the predetermined period has not elapsed (NO in step S26), step S26 is executed again.

[0121] In step S27, the second control device (C2) determines whether or not the first condition is satisfied. In this example, the first condition is a condition in which the state in which the first sensor (51) does not detect refrigerant and the second sensor (52) detects the gas at the third concentration continues for a predetermined time. If it is determined that the first condition is satisfied (YES in step S27), step S28 is executed. If it is determined that the first condition is not satisfied (NO in step S27), step S22 is executed again.

[0122] In step S28, the second control device (C2) transmits the first information to the third control device (C3).

[0123] In step S29, the third control device (C3) displays the first information on the first display unit (42). The first display unit (42) displays a message prompting the user to replace the first sensor (51). The first display unit (42) may display a message prompting the user to replace the first sensor (51) and the second sensor (52).

[0124] (10) Other embodiments The above embodiment and the above modified examples may be configured as follows.

[0125] As shown in FIG. 10, the first sensor (51) and the second sensor (52) may form a refrigerant leakage detection device (50). The refrigerant leakage detection device (50) is configured separately from the air conditioner (10). The refrigerant leakage detection device (50) may include a fifth control device (C5). The fifth control device (C5) is an example of the control unit (C2) of the present disclosure. In this case, the refrigerant leakage detection device (50) may have a display unit (53). The display unit (53) is an example of the notification unit (42) of the present disclosure. When the first sensor (51) does not detect a refrigerant, the fifth control device (C5) determines that the second sensor (52) has detected a refrigerant even in a state where there is no refrigerant, and causes the display unit (53) to display a message recommending replacement of the first sensor (51).

[0126] The first condition may be a state in which the first sensor (51) does not detect a refrigerant and the second sensor (52) detects a gas of a third concentration. In this case, unlike the above embodiment and modified example, a predetermined time does not need to be set. In other words, it may be determined that the first condition is satisfied when the first sensor (51) does not detect a refrigerant and the second sensor (52) detects a gas of a third concentration.

[0127] The target space (43) of the present disclosure may be a specific partitioned space in the indoor unit (30). The specific space includes a space such as the first space (43) in which leaked refrigerant is relatively likely to accumulate.

[0128] The target space (43) of the present disclosure may be in the vicinity of a potential source of refrigerant leakage, such as a connection between a refrigerant pipe, such as the first branch pipe (13b) and the second branch pipe (14b), and the indoor heat exchanger (32), or a connection between a refrigerant pipe and the indoor expansion valve (31).

[0129] The first sensor (51) and the second sensor (52) only need to be disposed in the target space (43) of the present disclosure, and do not need to be disposed in close proximity to each other.

[0130] The first sensor (51) and the second sensor (52) may be disposed in the vicinity of the drain pan (44).

[0131] The first sensor (51) and the second sensor (52) do not have to be arranged in the target space (43) of the present disclosure, but may be arranged close to each other inside the indoor unit (30).

[0132] The first sensor (51) and the second sensor (52) may be any sensor whose reaction becomes more sensitive due to deterioration caused by use over a certain period of time, and may not be a semiconductor type sensor.

[0133] The second sensor (52) does not have to be a sensor that detects refrigerant, and may detect, for example, a gas such as city gas. Even in this case, when the first sensor (51) does not detect refrigerant due to deterioration of the first sensor (51) and the second sensor (52) accompanying use for a certain period of time, the second sensor (52) detects the presence of city gas in the first space (43) even when there is no city gas.

[0134] The first sensor (51) and the second sensor (52) may be energized even when the air conditioner (10) is turned off, thereby making it possible to detect the refrigerant even when the air conditioner (10) is not operating.

[0135] The control unit (C2) of the present disclosure does not have to be provided in the second control device (C2), and may be provided in the first control device (C1) or the third control device (C3).

[0136] The first sensor (51) may determine that it has detected a refrigerant of a first concentration. In this case, the first sensor (51) determines that the refrigerant concentration around the first sensor (51) is at the first concentration by reading a detection value indicating the refrigerant of the first concentration. The first sensor (51) that has detected the refrigerant of the first concentration transmits a detection signal to the second control device (C2).

[0137] The second sensor (52) may determine that it has detected a refrigerant of a second concentration. In this case, the second sensor (52) determines that the refrigerant concentration around the second sensor (52) is at the second concentration by reading a detection value indicating the refrigerant of the second concentration. The second sensor (52) that has detected the refrigerant of the second concentration transmits a detection signal to the second control device (C2).

[0138] The refrigeration system (10) is not limited to an air conditioner (10). The refrigeration system (10) may be any system that includes a refrigerant circuit and performs a refrigeration cycle. For example, the refrigeration system of the present disclosure may be used in a refrigeration system for a refrigerator / freezer that cools the interior of the refrigerator / freezer, a chiller unit, a water heater, and the like.

[0139] The control device (AC) of the embodiment may be disposed in a control center that centrally manages a plurality of indoor units (30). In this case, the notification device (60) may be configured to notify a manager in the control center.

[0140] Although the embodiments and modifications have been described above, it will be understood that various modifications of form and details are possible without departing from the spirit and scope of the claims. Furthermore, the above embodiments and modifications may be appropriately combined or substituted as long as the functions of the subject of the present disclosure are not impaired. The descriptions "first", "second" and "third" described above are used to distinguish the words to which these descriptions are attached, and do not limit the number or order of the words. [Industrial Applicability]

[0141] INDUSTRIAL APPLICABILITY As described above, the present disclosure is useful for a refrigeration apparatus, a refrigerant leak detection device, and a refrigerant leak detection method. [Explanation of symbols]

[0142] 10 Air conditioning equipment (refrigeration equipment) 11 Refrigerant circuit 30 Indoor unit 43 First space (target space) 51 First Sensor 52 Second Sensor 42 First display unit (notification unit) C2 Second control device (control unit) S Air-conditioned space (indoor space)

Claims

1. a refrigerant circuit (11) through which a refrigerant circulates; a first sensor (51) for detecting a refrigerant in the target space (43); a second sensor (52) arranged in the same target space (43) as the first sensor (51) and configured to detect a predetermined gas; When the first sensor (51) does not detect a refrigerant due to deterioration of the first sensor (51) and the second sensor (52) caused by use for a predetermined period of time, the second sensor (52) detects the specified gas even in the absence of the specified gas. A refrigeration device characterized by:

2. the predetermined gas is a refrigerant, The second sensor (52) detects the refrigerant in the target space (43).

2. The refrigeration system according to claim 1.

3. the first sensor (51) detects a refrigerant having a first concentration; The second sensor (52) detects the predetermined gas at a concentration lower than the first concentration.

3. The refrigeration system according to claim 1 or 2.

4. the first sensor (51) detects a refrigerant having a first concentration; the second sensor (52) detects the predetermined gas at a concentration equal to the first concentration; The second sensor (52) deteriorates faster with use for a given period of time than the first sensor (51).

3. The refrigeration system according to claim 1 or 2.

5. a control unit (C2) that determines whether or not a first condition is satisfied, that is, the first sensor (51) does not detect a refrigerant and the second sensor (52) detects the predetermined gas.

5. The refrigeration system according to claim 1, wherein the refrigeration system comprises:

6. The control unit (C2) determines, as the first condition, that a condition that the first sensor (51) does not detect a refrigerant and the second sensor (52) detects the predetermined gas continues for a predetermined period of time.

6. The refrigeration system according to claim 5.

7. and a notification unit (42) for notifying a person that the first sensor (51) is deteriorated when the first condition is satisfied.

7. The refrigeration system according to claim 5 or 6.

8. An indoor unit (30) that conditions the air in a space (S) to be air-conditioned; The refrigeration apparatus according to any one of claims 1 to 7, wherein the first sensor (51) and the second sensor (52) are arranged inside the indoor unit (30).

9. a first sensor (51) for detecting a refrigerant in the target space (43); a second sensor (52) arranged in the same target space (43) as the first sensor (51) and configured to detect a predetermined gas; When the first sensor (51) does not detect a refrigerant due to deterioration of the first sensor (51) and the second sensor (52) caused by use for a predetermined period of time, the second sensor (52) detects the specified gas even in the absence of the specified gas. A refrigerant leak detection device characterized by the above.

10. a first sensor (51) for detecting a refrigerant in the target space (43); a second sensor (52) arranged in the same target space (43) as the first sensor (51) and configured to detect a predetermined gas; When the first sensor (51) does not detect a refrigerant due to deterioration of the first sensor (51) and the second sensor (52) caused by use for a predetermined period of time, the second sensor (52) detects the specified gas even in the absence of the specified gas. A method for detecting a refrigerant leak comprising:

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