Ventilation system

Abstract

To provide a ventilation system capable of promptly discharging a refrigerant leaked from an air conditioner to an indoor side.SOLUTION: A control section includes a normal air supply / exhaust mode and an emergency air supply / exhaust mode (S4). In the normal air supply / exhaust mode, an exhaust fan is operated in a predetermined air quantity range for exchanging heat in a heat exchange type ventilation device (first exhaust air quantity, second exhaust air quantity, third exhaust air quantity). In the emergency air supply / exhaust mode (S4), when a determination that a concentration Cr of a refrigerant detected by a refrigerant sensor is a predetermined concentration threshold value or larger is made on the basis of detection information acquired by an acquisition section, the exhaust fan is operated with air quantity (fourth exhaust air quantity) larger than the maximum air quantity (first air exhaust quantity) set in the air quantity range in the normal air supply / exhaust mode (S34).SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present disclosure relates to ventilation systems. [Background technology]

[0002] Some ventilation systems that ventilate rooms equipped with air conditioners are equipped with a heat exchanger type ventilation device to prevent the comfortable indoor temperature caused by air conditioning from being significantly reduced by ventilation (for example, Patent Document 1). A heat exchanger type ventilation device exchanges heat using a heat exchange element between exhaust air flowing from the room to the outside (outdoors) and supply air flowing from the outside (outdoors) to the room. This allows the ventilation system to supply outdoor air into the room after bringing the air taken in from the outside closer to the temperature of the room, even if the outdoor temperature is significantly different from the temperature of the air-conditioned room.

[0003] Meanwhile, air conditioners generally use a vapor compression refrigeration cycle, and in recent years, alternative refrigerants have been used to prevent ozone layer depletion. However, alternative refrigerants have a high greenhouse effect, and from the perspective of global warming, there is a need to switch to refrigerants with a lower greenhouse effect, such as hydrofluoroolefins (HFOs). However, refrigerants with a lower greenhouse effect are generally highly flammable, so if a refrigerant leaks from an air conditioner into a room, it is desirable to discharge the refrigerant outdoors.

[0004] In the ventilation system described in Patent Document 1, when a refrigerant leak from an air conditioner into a room is detected, the airflow rates of the ventilation device's intake fan and exhaust fan are controlled to the maximum airflow rate among multiple airflow setting levels that can be set during normal operation. This operation of the ventilation device exhausts the leaked refrigerant outside the room. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent Publication No. 2021-055903 Summary of the Invention [Problem to be solved by the invention]

[0006] However, in heat exchange ventilation systems, the upper limits of the set airflow rates of the supply air fan and the exhaust air fan are generally set low to ensure sufficient heat exchange in the heat exchange element. This is because if the supply airflow rate and the exhaust airflow rate are too high, the supply air and the exhaust air will pass through the heat exchange element without sufficient heat exchange. Therefore, the ventilation system described in Patent Document 1 has the problem that in an emergency when refrigerant leaks from the air conditioner into the room, it is difficult to quickly exhaust the refrigerant from the room to the outside.

[0007] The present disclosure has been made to solve the above-mentioned problems, and aims to provide a ventilation system that can quickly discharge refrigerant that has leaked from an air conditioner into the room. [Means for solving the problem]

[0008] To achieve this object, a ventilation system according to one aspect of the present disclosure uses a heat exchange ventilation device to ventilate a room conditioned by an air conditioner, and includes an intake air duct, an exhaust air duct, an intake fan, an exhaust fan, an acquisition unit, and a control unit. The heat exchange ventilation device exchanges heat using a heat exchange element between exhaust air flowing from the room to the outside and intake air flowing from the outside to the room. The intake air duct connects the outside to the room via the heat exchange element. The exhaust air duct connects the inside to the outside via the heat exchange element. The intake fan guides the intake air into the room via the intake air duct. The exhaust fan guides the exhaust air to the outside via the exhaust air duct. The acquisition unit acquires detection information from a refrigerant sensor that detects refrigerant leaks from the air conditioner. The control unit has a normal exhaust mode and an emergency exhaust mode. In the normal exhaust mode, the exhaust fan operates within a predetermined airflow range for heat exchange in the heat exchange ventilation device. In the emergency exhaust mode, if it is determined that the refrigerant concentration detected by the refrigerant sensor is equal to or higher than a predetermined concentration threshold based on the detection information acquired by the acquisition unit, the exhaust fan is operated at an air volume greater than the maximum air volume set in the air volume range of the normal exhaust mode. [Effects of the Invention]

[0009] According to the present disclosure, it is possible to quickly discharge refrigerant that has leaked from an air conditioner into a room. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a schematic configuration diagram of a ventilation system according to an embodiment of the present invention. [Figure 2] FIG. 2 is a schematic diagram of a heat exchange type ventilation device that constitutes the ventilation system. [Figure 3] (a) is a diagram showing the state in which the exhaust air duct switching unit of the ventilation system has switched to the exhaust air duct as the exhaust air duct, and (b) is a diagram showing the state in which the exhaust air duct switching unit has switched to the bypass exhaust air duct as the exhaust air duct. [Figure 4] 4 is a flowchart showing ventilation control executed by a control unit of the ventilation system. [Figure 5]10 is a flowchart showing a normal air supply / exhaust mode, which is one control mode of the ventilation control. [Figure 6] 10 is a flowchart showing an emergency ventilation mode, which is one control mode of the ventilation control. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments for carrying out the present disclosure will be described with reference to the accompanying drawings. Each of the embodiments described below represents a preferred specific example of the present disclosure. Therefore, the numerical values, shapes, materials, and components, as well as the arrangement and connection of the components, shown in the following embodiments are merely examples and are not intended to limit the present disclosure. Therefore, among the components in the following embodiments, components that are not recited in the independent claims that represent the highest concept of the present disclosure will be described as optional components. Furthermore, in each drawing, substantially identical components are assigned the same reference numerals, and redundant explanations will be omitted or simplified.

[0012] First, the configuration of a ventilation system 1 according to an embodiment of the present invention will be described with reference to Figures 1 and 2. Figure 1 is a schematic configuration diagram of the ventilation system 1. Figure 2 is a schematic configuration diagram of a heat exchange type ventilation device 3 that constitutes the ventilation system 1.

[0013] The ventilation system 1 ventilates a room 61 that is air-conditioned by an air conditioner 2. Before describing the detailed configuration of the ventilation system 1, the air conditioner 2 will be described.

[0014] The air conditioner 2 has a general configuration and detailed description thereof will be omitted, but it uses a vapor compression refrigeration cycle to perform air conditioning control (cooling, dehumidifying, or heating) on ​​the air in the room 61. The air conditioner 2 is made up of an indoor unit 21, an outdoor unit 22, and an air conditioner remote controller 25. In the example shown in Fig. 1, the indoor unit 21 is provided as a ceiling-embedded type that is embedded in the attic 62 with its bottom surface (panel surface) exposed to the ceiling 63, but this is not necessarily limited to this and it may also be provided as a wall-mounted type that is attached to the wall of the room 61 near the ceiling 63, etc.

[0015] The air conditioner remote controller 25 is an input interface that accepts settings related to the operation of the air conditioner 2 through user operation. The operating mode of the air conditioner 2 (cooling, dehumidification, heating), as well as the set temperature (target temperature) and set humidity (target humidity) of the room 61, are set by the user operating the air conditioner remote controller 25. The air conditioner remote controller 25 may be realized by a mobile information terminal such as a smartphone that has an application that can make these settings.

[0016] The air conditioner remote controller 25 is connected by wire or wirelessly to an air conditioning control unit 23 provided in the indoor unit 21 of the air conditioner 2. The air conditioning control unit 23 controls the operation of the air conditioner 2 based on setting information received by the air conditioner remote controller 25 and detection results of various sensors that detect the temperature, humidity, etc. of the room 61.

[0017] The air conditioner 2 is also provided with a refrigerant sensor 24. The refrigerant sensor 24 is a sensor that detects leakage of refrigerant used in the refrigeration cycle of the air conditioner 2. Specifically, the refrigerant sensor 24 detects the concentration Cr (see FIG. 4 ) of refrigerant in the air path within the indoor unit 21 (i.e., the air path from when air is drawn in from the room 61 to when it is air-conditioned and blown out into the room 61). Detection information including information indicating the refrigerant concentration Cr detected by the refrigerant sensor 24 is transmitted to the air conditioning control unit 23. The air conditioning control unit 23 transmits the detection information received from the refrigerant sensor 24 to the ventilation system 1.

[0018] Note that the refrigerant sensor 24 only needs to be able to detect refrigerant leakage from the air conditioner 2, and its installation location does not necessarily have to be in the air duct within the indoor unit 21. For example, the refrigerant sensor 24 may be installed in the room 61 and detect a refrigerant leakage from the air conditioner 2 by detecting the refrigerant concentration Cr in the room 61. Furthermore, detection information including information indicating the refrigerant concentration Cr detected by the refrigerant sensor 24 may be sent directly to the ventilation system 1 without going through the air conditioning control unit 23.

[0019] Next, we will explain the detailed configuration of the ventilation system 1. As shown in Figures 1 and 2, the ventilation system 1 includes a heat exchange type ventilation device 3, which includes an intake air duct 4, an exhaust air duct 5, a bypass exhaust air duct 6, an intake fan 39, an exhaust fan 40, an exhaust air duct switching unit 41, an exhaust refrigerant sensor 71, a control unit 42, an acquisition unit 43, a timer unit 49, and a ventilation remote controller 65.

[0020] The heat exchange type ventilation device 3 is provided with a heat exchange element 38, and heat is exchanged in the heat exchange element 38 between exhaust air flowing from the room 61 to the outside (outdoors) 64 and supply air flowing from the outside 64 to the room 61. Here, the exhaust air is air flowing through the exhaust air duct 5 or the bypass exhaust air duct 6, which will be described later. The supply air is air flowing through the supply air duct 4, which will be described later.

[0021] The heat exchange type ventilation device 3 is installed in the attic 62, and its housing has an outside air intake port 31, an air supply outlet 32, a return air intake port 34, and an exhaust outlet 35. The heat exchange type ventilation device 3 also has an in-device air supply duct 33, an in-device exhaust duct 36, an in-device bypass exhaust duct 37, an outdoor temperature sensor 45, and an indoor temperature sensor 46 inside the housing.

[0022] Heat exchange element 38 is provided at the intersection of intake air duct 4 (described later) and exhaust air duct 5 (described later), and is an element in which intake air ducts 4 and exhaust air ducts 5 are alternately stacked with a heat transfer plate (not shown) sandwiched therebetween. Heat exchange element 38 exchanges heat and humidity (total heat exchange) between intake air flowing through intake air duct 4 and exhaust air flowing through exhaust air duct 5 via the heat transfer plate. Note that heat exchange element 38 may also exchange only heat (sensible heat exchange) between intake air flowing through intake air duct 4 and exhaust air flowing through exhaust air duct 5 via the heat transfer plate.

[0023] The outdoor air intake 31 is connected to an outdoor air intake 51 provided on the outer wall of a building having an interior room 61 via an outdoor air duct 53, and takes in outdoor air (OA), which is air from outside the room 64, sucked in through the outdoor air intake 51 into the heat exchange type ventilation device 3.

[0024] The supply air outlet 32 ​​blows out the outside air (OA) taken into the heat exchange type ventilation device 3 from the outside air inlet 31 as supply air (SA) through a heat exchange element 38. The supply air outlet 32 ​​is connected to an indoor outlet 52 provided on the ceiling 63 toward the room 61 via an intake air duct 54. As a result, the supply air (SA) blown out from the supply air outlet 32 ​​is blown out from the indoor outlet 52 into the room 61.

[0025] The internal supply air duct 33 is an air duct within the heat exchange type ventilation device 3 that connects the outside air inlet 31 and the supply air outlet 32 ​​via the heat exchange element 38. Outside air (OA) taken into the heat exchange type ventilation device 3 from the outside air inlet 31 passes through the internal supply air duct 33 as supply air via the heat exchange element 38 and is blown out from the supply air outlet 32 ​​as supply air (SA).

[0026] The outside air duct 53, the in-device supply air duct 33, and the supply air duct 54 form the supply air duct 4. That is, the supply air duct 4 is an air duct that connects the outside 64 and the inside 61 via the heat exchange element 38.

[0027] 2 is provided upstream of the heat exchange element 38 in the internal supply air duct 33. The outdoor air filter 48 purifies the supply air taken into the heat exchange ventilation device 3 from the outdoors 64 by removing dirt and dust. That is, the supply air purified by the outdoor air filter 48 passes through the heat exchange element 38, thereby preventing the heat exchange element 38 from becoming clogged with dirt and dust.

[0028] The return air intake 34 is connected to an indoor intake 55 provided on the ceiling 63 facing the room 61 via a return air duct 57, and takes in return air (RA), which is the air from the room 61 sucked in through the indoor intake 55, into the heat exchange type ventilation device 3.

[0029] The exhaust air outlet 35 blows out the return air (RA) taken into the heat exchange type ventilation device 3 from the return air inlet 34 as exhaust air (EA) either via a heat exchange element 38 or without passing through the heat exchange element 38. The exhaust air outlet 35 is connected to an outdoor air outlet 56 provided on the outer wall of a building having an interior space 61 via an exhaust duct 58. As a result, the exhaust air (EA) blown out from the exhaust air outlet 35 is blown out from the outdoor air outlet 56 to the outside 64.

[0030] The internal exhaust air duct 36 is an air duct within the heat exchange type ventilation device 3 that connects the return air inlet 34 and the exhaust air outlet 35 via the heat exchange element 38. The return air (RA) taken into the heat exchange type ventilation device 3 from the return air inlet 34 can pass through the internal exhaust air duct 36 as exhaust air by the exhaust air duct switching unit 41, which will be described later, while passing through the heat exchange element 38. The exhaust air that has passed through the internal exhaust air duct 36 is blown out from the supply air outlet 32 ​​as exhaust air (EA).

[0031] The return air duct 57, the internal exhaust air duct 36, and the exhaust duct 58 form the exhaust air duct 5. That is, the exhaust air duct 5 is an air duct that connects the indoor space 61 and the outdoor space 64 via the heat exchange element 38.

[0032] When air is exhausted from the room 61 to the outside 64 via the exhaust airflow duct 5, heat is exchanged by the heat exchange element 38 between the exhaust air and the supply air flowing from the outside 64 to the room 61 via the supply airflow duct 4. As a result, even if the temperature Ti of the room 61 (see FIG. 6) and the temperature To of the outside 64 (see FIG. 6) are significantly different, the temperature of the supply air (SA) can be brought close to the temperature Ti of the room 61 before being taken into the room 61. Therefore, it is possible to prevent the temperature Ti of the room 61, which is air-conditioned by the air conditioner 2, from being significantly disturbed by the supply air (SA) of the ventilation system 1, and it is possible to achieve energy savings in the air conditioner 2.

[0033] A return air-side filter 47 is provided upstream of the heat exchange element 38 in the internal exhaust air duct 36. The return air-side filter 47 purifies the return air (RA) taken in from the room 61 to the heat exchange type ventilation device 3 by removing dirt and dust. That is, the exhaust air purified by the return air-side filter 47 passes through the heat exchange element 38, thereby preventing the heat exchange element 38 from becoming clogged with dirt and dust.

[0034] The in-apparatus bypass exhaust air duct 37 is an air duct inside the heat exchange type ventilation device 3 that connects the return air inlet 34 and the exhaust air outlet 35 without passing through the heat exchange element 38. The return air (RA) taken into the heat exchange type ventilation device 3 from the return air inlet 34 can pass through the in-apparatus bypass exhaust air duct 37 as exhaust air without passing through the heat exchange element 38 by the exhaust air duct switching unit 41 described later. The exhaust air that has passed through the in-apparatus bypass exhaust air duct 37 is also blown out from the supply air outlet 32 ​​as exhaust air (EA).

[0035] The return air duct 57, the in-apparatus bypass exhaust air duct 37, and the exhaust duct 58 form a bypass exhaust air duct 6. That is, the bypass exhaust air duct 6 is an air duct that connects the indoor space 61 with the outdoor space 64 without passing through the heat exchange element 38.

[0036] Because bypass exhaust air duct 6 does not pass through heat exchange element 38, there is no pressure loss due to heat exchange element 38. In addition, internal bypass exhaust air duct 37 is not provided with a filter like return air side filter 47 that is provided in internal exhaust air duct 36. This is because internal bypass exhaust air duct 37 does not have anything in the air duct that can cause clogging like heat exchange element 38. Compared to exhaust air duct 5, bypass exhaust air duct 6 has the advantage of being able to reduce pressure loss due to heat exchange element 38 and return air side filter 47.

[0037] Furthermore, heat exchange element 38 may not be able to completely separate supply air duct 4 and exhaust air duct 5 as ideally, and a gap may be formed that connects supply air duct 4 and exhaust air duct 5. This may cause some of the exhaust air flowing through exhaust air duct 5 to leak into supply air duct 4 via heat exchange element 38 and be blown into room 61 as supply air (SA) together with the supply air. If exhaust is performed using bypass exhaust air duct 6, the exhaust air does not pass through heat exchange element 38, and it is therefore possible to prevent some of the exhaust air that has leaked into supply air duct 4 from being blown into room 61 as supply air (SA).

[0038] The outdoor temperature sensor 45 is a sensor provided inside the housing of the heat exchanger type ventilation device 3 near the outdoor air inlet 31 (at least upstream of the heat exchange element 38 of the internal supply air duct 33). The outdoor temperature sensor 45 detects the temperature of the outdoor air (OA) taken into the heat exchanger type ventilation device 3, i.e., the temperature To of the outdoor 64. In other words, the outdoor temperature sensor 45 detects the temperature To of the supply air before heat exchange. Information on the outdoor 64 temperature To detected by the outdoor temperature sensor 45 is sent to the control unit 42. Note that the outdoor temperature sensor 45 does not have to be installed inside the housing of the heat exchanger type ventilation device 3 as long as it can detect the temperature To of the outdoor 64. For example, the outdoor temperature sensor 45 may be installed outside the outdoor 64 or in the outdoor air duct 53.

[0039] The indoor temperature sensor 46 is a sensor provided inside the housing of the heat exchanger-type ventilation device 3 near the return air inlet 34 (at least upstream of the heat exchange element 38 of the internal exhaust air duct 36 of the device). The indoor temperature sensor 46 detects the temperature of the return air (RA) taken into the heat exchanger-type ventilation device 3, i.e., the temperature Ti of the indoor space 61. In other words, the indoor temperature sensor 46 detects the temperature Ti of the exhaust air before heat exchange. Information on the temperature Ti of the indoor space 61 detected by the indoor temperature sensor 46 is sent to the control unit 42. Note that the indoor temperature sensor 46 does not have to be installed inside the housing of the heat exchanger-type ventilation device 3 as long as it can detect the temperature Ti of the indoor space 61. For example, the indoor temperature sensor 46 may be installed in the indoor space 61, in a ventilation remote controller 65 provided in the indoor space 61, or in the return air duct 57. In the present disclosure, the indoor temperature sensor 46 is arranged upstream of the exhaust air duct switching unit 41 as shown in FIG. 2, as an example. With this arrangement, the temperature Ti can be easily detected whether the air passes through the internal exhaust air duct 36 or the internal bypass exhaust air duct 37.

[0040] The exhaust fan 40 is provided in an air duct that serves both the internal exhaust air duct 36 and the internal bypass exhaust air duct 37, and is a fan for guiding the return air (RA) as exhaust air (EA) to the outside 64 via the exhaust air duct 5 or the bypass exhaust air duct 6. The air volume of the exhaust fan 40 is controlled by the control unit 42.

[0041] For example, in the normal air supply / exhaust mode (S3, see Figure 5) when no refrigerant leakage from the air conditioner 2 is detected, the air is controlled so that exhaust is performed at an air volume specified within a predetermined air volume range, depending on the ventilation intensity set by the ventilation remote controller 65.

[0042] Furthermore, if a refrigerant leak from the air conditioner 2 is detected, the exhaust fan 40 is controlled to operate in emergency air supply / exhaust mode (S4, see Figure 6) at an air volume greater than the maximum air volume set within the air volume range of the normal air supply / exhaust mode (S3).

[0043] The air supply fan 39 is provided in the internal air supply duct 33, and is a fan for guiding the outside air (OA) as the supply air (SA) into the room 61 via the air supply duct 4. The air volume of the air supply fan 39 is controlled by the control unit .

[0044] For example, in the normal air supply / exhaust mode (S3, see Figure 5) when no refrigerant leakage from the air conditioner 2 is detected, the air supply is controlled to be at an air volume specified within a predetermined air volume range according to the ventilation intensity set by the ventilation remote controller 65.

[0045] Furthermore, if a refrigerant leak from the air conditioner 2 is detected, the control unit 42 controls the air supply fan 39 to operate in emergency air supply / exhaust mode (S4, see Figure 6) at an air volume greater than the maximum air volume set within the air volume range of the normal air supply / exhaust mode (S3).

[0046] In addition, the air volume set for exhaust fan 40 and / or intake fan 39 may be controlled to be different when exhaust is performed through exhaust air duct 5, which passes through heat exchange element 38, and when exhaust is performed through bypass exhaust air duct 6, which does not pass through heat exchange element 38.

[0047] Specifically, when exhaust air is discharged through exhaust air duct 5, sufficient heat exchange must occur between the exhaust air and the intake air in normal air supply / exhaust mode (S3). Therefore, in normal air supply / exhaust mode (S3), the maximum airflow rates (first exhaust airflow rate or first intake airflow rate shown in FIG. 5) set for exhaust fan 40 and / or intake fan 39 are set smaller than the maximum airflow rates when exhaust air is discharged through bypass exhaust air duct 6, so as not to reduce the heat exchange efficiency.

[0048] In other words, there is no need to consider the efficiency of heat exchange between the exhaust air and the intake air when exhaust is performed through bypass exhaust air duct 6. Therefore, the maximum airflow rates (first exhaust airflow rate or first intake airflow rate shown in FIG. 5 ) set for exhaust fan 40 and / or intake air fan 39 in normal air supply / exhaust mode (S3) may be set to be greater than the maximum airflow rates when exhaust is performed through exhaust air duct 5.

[0049] Therefore, in the emergency air supply / exhaust mode (S4), when exhausting air through bypass exhaust duct 6, exhaust fan 40 may be controlled to operate at the maximum air volume set within the air volume range of the normal air supply / exhaust mode (S3) when exhausting air through bypass exhaust duct 6. In this case, air supply fan 39 may also be controlled to operate at the maximum air volume set within the air volume range of the normal air supply / exhaust mode (S3) when exhausting air through bypass exhaust duct 6.

[0050] The exhaust airflow path switching unit 41 is provided within the heat exchange type ventilation device 3, and is a damper that switches between the exhaust airflow path 5 and the bypass exhaust airflow path 6 as the airflow path for exhaust air flowing from the indoors 61 to the outdoors 64 under the control of the control unit 42.

[0051] Here, the role of exhaust airflow path switching unit 41 will be specifically described with reference to Fig. 3. Fig. 3(a) is a diagram showing a state in which exhaust airflow path switching unit 41 has switched to exhaust airflow path 5 as the airflow path for exhaust air flowing from indoors 61 to outdoors 64. Fig. 3(b) is a diagram showing a state in which exhaust airflow path switching unit 41 has switched to bypass exhaust airflow path 6 as the airflow path for exhaust air flowing from indoors 61 to outdoors 64.

[0052] The control unit 42 controls the exhaust airflow path switching unit 41 to switch between the exhaust airflow path 5 and the bypass exhaust airflow path 6 based on the temperature Ti of the room 61 detected by the room temperature sensor 46 and the temperature To of the outside room 64 detected by the outdoor temperature sensor 45.

[0053] Specifically, when the absolute value of the difference between the temperature Ti in the room 61 and the temperature To in the outdoor room 64 is equal to or greater than a predetermined temperature difference, the exhaust airflow path switching unit 41 is controlled to switch the airflow path for the exhaust air to the exhaust airflow path 5, as shown in Fig. 3(a). As a result, heat is exchanged by the heat exchange element 38 between the exhaust air flowing through the exhaust airflow path 5 and the supply air flowing through the supply airflow path 4, so that the temperature of the supply air can be brought close to the temperature Ti in the room 61 before being taken into the room 61, as described above.

[0054] Furthermore, when the absolute value of the difference between the temperature Ti in the room 61 and the temperature To in the outdoor room 64 is less than a predetermined temperature difference, the exhaust airflow path switching unit 41 is controlled to switch the exhaust air path to the bypass exhaust airflow path 6, as shown in FIG. 3(b). As described above, the bypass exhaust airflow path 6 does not have pressure loss due to the heat exchange element 38 or the return air-side filter 47, and changes in pressure loss over time due to clogging are small, compared to the exhaust airflow path 5, so the exhaust air volume can be increased. Furthermore, by performing exhaust using the bypass exhaust airflow path 6, it is possible to prevent some of the exhaust air leaking into the supply airflow path 4 from being blown into the room 61 as supply air (SA).

[0055] 1 and 2, the description of the ventilation system 1 will continue. The acquisition unit 43 acquires detection information from the refrigerant sensor 24, which detects refrigerant leakage from the air conditioner 2, via the air conditioning control unit 23. This detection information includes information indicating the concentration Cr of refrigerant in the air path within the indoor unit 21 (i.e., the air path from when air is sucked in from the room 61 to when it is air-conditioned and blown out into the room 61). The detection information of the refrigerant sensor 24 acquired by the acquisition unit 43 is output to the control unit 42.

[0056] The timer unit 49 measures the post-discharge elapsed time te (see FIG. 6). The post-discharge elapsed time te is the time elapsed since the refrigerant concentration Cr detected by the refrigerant sensor 24 transitioned from a state equal to or greater than a predetermined concentration threshold to a state below the predetermined concentration threshold. The post-discharge elapsed time te is referenced by the control unit 42 and is used to determine whether to end the emergency air supply / exhaust mode (S4).

[0057] The exhaust refrigerant sensor 71 is a sensor that detects the concentration Ce (see FIG. 6 ) of refrigerant contained in air (return air (RA)) drawn into the heat exchanger-type ventilation device 3 from the indoor space 61. The exhaust refrigerant sensor 71 is provided, for example, near the return air inlet 34 inside the housing of the heat exchanger-type ventilation device 3 (at least upstream of the exhaust air-channel switching unit 41 in the internal supply air duct 33). However, the exhaust refrigerant sensor 71 may be installed anywhere as long as it can detect the concentration Ce of refrigerant contained in the air (return air (RA)) drawn into the heat exchanger-type ventilation device 3 from the indoor space 61. For example, the exhaust refrigerant sensor 71 may be provided inside the housing of the heat exchanger-type ventilation device 3 in an air duct that serves both the internal exhaust air duct 36 and the internal bypass exhaust air duct 37, or it may be provided in the return air duct 57 instead of inside the heat exchanger-type ventilation device 3.

[0058] Information on the refrigerant concentration Ce contained in the return air (RA) detected by the exhaust refrigerant sensor 71 is transmitted to the control unit 42. Based on the information on the refrigerant concentration Ce contained in the return air (RA), the control unit 42 determines whether the heat exchanger-type ventilation device 3 is successfully drawing the refrigerant from the room 61. When the heat exchanger-type ventilation device 3 is not successfully drawing the refrigerant from the room 61, the control unit 42 controls the air volume of the supply air (SA) and the air volume of the exhaust air (EA) so that the room 61 becomes positive pressure. When the room 61 becomes positive pressure, the refrigerant accumulated in the room 61 is discharged to the outside of the room 61 through gaps in the room 61 or a louver 66 (described later). Here, the outside of the room 61 may be any space different from the room 61. For example, it may be the outside room 64, or a room or a hallway different from the room 61.

[0059] The ventilation remote controller 65 is an input interface that accepts, through user operation, settings related to the operation of the ventilation system 1. For example, the ventilation strength (weak, medium, strong) of the ventilation system 1 is set by the user operating the ventilation remote controller 65.

[0060] The ventilation remote controller 65 is connected to the control unit 42 by wire or wirelessly. When the ventilation remote controller 65 accepts a user operation, it transmits setting information accepted by the operation to the control unit 42 by wire or wirelessly. The ventilation remote controller 65 also has a function of issuing a predetermined notification to the user based on an instruction from the control unit 42. For example, when the exhaust fan 40 is operating in the emergency air supply / exhaust mode described below, the control unit 42 instructs the ventilation remote controller 65 to issue a notification that the ventilation intensity setting will not be accepted. In response to this, the ventilation remote controller 65 notifies the user of this by means of a text string, a sound, a lit or flashing light-emitting diode, or the like.

[0061] The ventilation remote controller 65 may be realized by a mobile information terminal such as a smartphone having an application capable of performing these settings and notifications.

[0062] The control unit 42 controls the operation of the ventilation system 1. The control unit 42 receives inputs such as information on the temperature Ti of the room 61 detected by the room temperature sensor 46, information on the temperature To of the outdoor room 64 detected by the outdoor temperature sensor 45, information on the detection of refrigerant leakage by the refrigerant sensor 24 acquired by the acquisition unit 43, information on the refrigerant concentration Ce contained in the return air (RA) detected by the exhaust refrigerant sensor 71, the elapsed time since discharge te measured by the timer unit 49, and setting information set for the ventilation remote controller 65. Based on this information, the control unit 42 controls the switching of the exhaust air passage switching unit 41, the air volume of the supply air fan 39, the air volume of the exhaust fan 40, etc.

[0063] For example, control unit 42 normally executes a normal air supply / exhaust mode (S3) in which the exhaust air volume of exhaust fan 40 is set to a specific air volume from a predetermined air volume range in accordance with the ventilation strength (weak, medium, strong) set by ventilation remote controller 65. In this normal air supply / exhaust mode (S3), the exhaust air volume of air supply fan 39 is also set to a specific air volume from a predetermined air volume range in accordance with the ventilation strength (weak, medium, strong) set by ventilation remote controller 65.

[0064] Furthermore, when exhaust is performed through exhaust air duct 5 via heat exchange element 38, control unit 42 sets the predetermined air volume range of exhaust fan 40 and the predetermined air volume range of intake fan 39 to air volume ranges for heat exchange in heat exchange type ventilation device 3. In other words, control unit 42 has a normal intake / exhaust mode (S3) in which exhaust fan 40 and intake fan 39 are each operated within the predetermined air volume ranges for heat exchange in heat exchange type ventilation device 3.

[0065] In this embodiment, the predetermined air volume range for exhaust fan 40 is set to first exhaust air volume > second exhaust air volume > third exhaust air volume (the inequality sign indicates the relationship between the magnitudes of the air volumes). Furthermore, the predetermined air volume range for supply fan 39 is set to first supply air volume > second supply air volume > third supply air volume (the inequality sign indicates the relationship between the magnitudes of the air volumes). When the ventilation intensity set by ventilation remote controller 65 is "strong," control unit 42 sets the exhaust air volume of exhaust fan 40 to the first exhaust air volume and the supply air volume of supply fan 39 to the first supply air volume. When the ventilation intensity is "medium," control unit 42 sets the exhaust air volume of exhaust fan 40 to the second exhaust air volume and the supply air volume of supply fan 39 to the second supply air volume. Furthermore, when the ventilation strength is "weak," control unit 42 sets the exhaust air volume of exhaust fan 40 to a third exhaust air volume, and sets the supply air volume of supply air fan 39 to a third supply air volume.

[0066] In other words, the ventilation remote controller 65 allows the user of the heat exchanger type ventilation device 3 to set a specific air volume from a predetermined air volume range of the exhaust fan 40. It can also be said that the ventilation remote controller 65 allows the user of the heat exchanger type ventilation device 3 to set a specific air volume from a predetermined air volume range of the supply fan 39.

[0067] Furthermore, when control unit 42 determines that refrigerant concentration Cr detected by refrigerant sensor 24 is equal to or greater than a predetermined concentration threshold based on information acquired from refrigerant sensor 24 by acquisition unit 43, control unit 42 executes emergency air supply / exhaust mode (S4). In emergency air supply / exhaust mode (S4), exhaust fan 40 and air supply fan 39 are controlled to operate at air volumes (fourth exhaust air volume, fourth air supply volume) greater than the maximum air volumes (first exhaust air volume, first air supply volume) set within the air volume range of normal air supply / exhaust mode (S3).

[0068] Note that the room 61 may be provided with not only the ventilation system 1 but also a louver 66. The louver 66 is attached to the wall or the lower part of the door of the room 61, and is an air vent that connects the room 61 to the outside of the room 61. The room 61 can be ventilated not only by the ventilation system 1 but also by the louver 66.

[0069] Next, ventilation control of the ventilation system 1 executed by the control unit 42 will be described with reference to Figs. 4 to 6. Fig. 4 is a flowchart showing the ventilation control. Fig. 5 is a flowchart showing a normal air supply / exhaust mode (S3) executed under normal circumstances as one control mode of ventilation control. Fig. 6 is a flowchart showing an emergency air supply / exhaust mode (S4) executed as one control mode of ventilation control when a refrigerant leak from the air conditioner 2 is detected.

[0070] The control unit 42 starts to execute the ventilation control shown in FIG. 4 when the power of the ventilation system 1 is turned on, or when the ventilation remote controller 65 instructs the ventilation system 1 to start ventilation operation based on the user's operation.

[0071] When ventilation control is started, the control unit 42 first acquires, via the acquisition unit 43, the refrigerant concentration Cr in the air duct inside the indoor unit 21 of the air conditioner 2, which is included in the detection information transmitted from the refrigerant sensor 24 (S1). Then, the control unit 42 determines whether the refrigerant concentration Cr is equal to or greater than a predetermined concentration threshold (S2).

[0072] If the result of this determination is that the refrigerant concentration Cr is less than the predetermined concentration threshold (S2: No), the control unit 42 determines that there is no refrigerant leakage from the air conditioner 2 and executes the normal air supply / exhaust mode shown in Fig. 5 (S3). This normal air supply / exhaust mode corresponds to the "normal exhaust mode" and also to the "normal air supply mode" of the present disclosure. When the control unit 42 finishes executing the normal air supply / exhaust mode (S3), it returns to the processing of S1.

[0073] On the other hand, if the result of the determination in S2 is that the refrigerant concentration Cr is equal to or greater than the predetermined concentration threshold (S2: Yes), the control unit 42 determines that there is a refrigerant leak from the air conditioner 2 and executes the emergency air supply / exhaust mode shown in Fig. 6 (S4). This emergency air supply / exhaust mode corresponds to the "emergency exhaust mode" and also to the "emergency air supply mode" in the present disclosure. When the control unit 42 ends execution of the emergency air supply / exhaust mode (S4), it switches to execution of the normal air supply / exhaust mode (S3).

[0074] Then, the control unit 42 repeatedly executes the processes of S1 to S4 until the power supply of the ventilation system 1 is opened (turned off) or until the ventilation remote controller 65 instructs the ventilation system 1 to stop the ventilation operation based on the user's operation.

[0075] In the normal air supply / exhaust mode (S3), as shown in Fig. 5, the control unit 42 first acquires the temperature Ti of the room 61 from the room temperature sensor 46, and acquires the temperature To of the outside room 64 from the outside temperature sensor 45 (S11). Then, the control unit 42 determines whether the absolute value of the difference between the temperature Ti of the room 61 and the temperature To of the outside room 64 is less than a predetermined temperature difference (S12).

[0076] As a result, if it is determined that the absolute value of the difference between the temperature Ti of the room 61 and the temperature To of the outside room 64 is less than a predetermined temperature difference (S12: Yes), the control unit 42 controls the ventilation operation of the ventilation system 1 so that the exhaust in the heat exchange type ventilation device 3 is performed through the bypass exhaust air duct 6 (S13).

[0077] Specifically, when the current exhaust air path is exhaust air path 5, control unit 42 temporarily stops exhaust fan 40 and then controls exhaust air path switching unit 41 to switch to bypass exhaust air path 6. The reason why control unit 42 temporarily stops exhaust fan 40 here is because if exhaust air path switching unit 41 is operated while exhaust is continuing, the exhaust puts a load on exhaust air path switching unit 41, making exhaust air path switching unit 41 more likely to malfunction. By temporarily stopping exhaust fan 40 and switching exhaust air path switching unit 41, control unit 42 can prevent malfunction of exhaust air path switching unit 41.

[0078] If the current exhaust air passage is the bypass exhaust air passage 6, the exhaust air passage is maintained in the bypass exhaust air passage 6 as is.

[0079] Then, control unit 42 sets the air volume of exhaust fan 40 and the air volume of supply air fan 39 in accordance with the ventilation intensity set by ventilation remote controller 65. At this time, the air volume of exhaust fan 40 and the air volume of supply air fan 39 are each set to a specific air volume corresponding to the ventilation intensity set by ventilation remote controller 65 within a predetermined air volume range that is determined in advance for the case where exhaust air is discharged through bypass exhaust air duct 6. In this case, the predetermined air volume range can be set up to a large air volume because it is not necessary to take heat exchange efficiency into consideration.

[0080] As a result, in the normal air supply / exhaust mode (S3) in which leakage of refrigerant into the room 61 is suppressed, the ventilation system 1 can perform exhaust using the bypass exhaust air duct 6 if the absolute value of the difference between the temperature Ti in the room 61 and the temperature To of the outdoor 64 is less than a predetermined temperature difference. Therefore, when the temperature Ti in the room 61 and the temperature To of the outdoor 64 are close to each other, ventilation can be performed by increasing the air volumes of the exhaust air (EA) and the supply air (SA) without performing heat exchange between the exhaust air and the supply air.

[0081] When the control unit 42 finishes the process of S13, it ends the process of the normal air supply / exhaust mode and returns to the process of S1 of ventilation control (see FIG. 4).

[0082] On the other hand, if it is determined in S12 that the absolute value of the difference between the temperature Ti in the room 61 and the temperature To in the outdoor 64 is equal to or greater than the predetermined temperature difference (S12: No), the control unit 42 sets the exhaust air path to exhaust air path 5 (S14). That is, if the current exhaust air path is bypass exhaust air path 6, the control unit 42 temporarily stops the exhaust fan 40 and then controls the exhaust air path switching unit 41 to switch to exhaust air path 5. The reason for temporarily stopping the exhaust fan 40 is as described in the description of the processing in S13. If the current exhaust air path is exhaust air path 5, the exhaust air path is maintained in exhaust air path 5.

[0083] As a result, in the normal air supply / exhaust mode (S3) in which no refrigerant is leaking into the room 61, the ventilation system 1 can ventilate the exhaust air using the exhaust air duct 5 if the absolute value of the difference between the temperature Ti in the room 61 and the temperature To in the outdoor 64 is equal to or greater than a predetermined temperature difference. Here, the exhaust air duct 5 is an air duct that passes through the heat exchange element 38. Therefore, when the temperature difference between the room 61 and the outdoor 64 is large, heat is exchanged between the exhaust air and the intake air by the heat exchange element 38. Therefore, the temperature of the intake air (SA) can be brought close to the temperature Ti in the room 61 before being taken into the room 61. As a result, the temperature Ti of the room 61, which is air-conditioned by the air conditioner 2, can be prevented from being significantly disturbed by the intake air (SA) of the ventilation system 1, thereby achieving energy savings in the air conditioner 2.

[0084] After the process of S14, next, control unit 42 determines the ventilation intensity (set ventilation intensity) set by the user via ventilation remote controller 65 (S15). If the result of the determination in S15 is that the set ventilation intensity is "strong" (S15: "strong"), control unit 42 controls exhaust fan 40 to operate at a first exhaust airflow rate (S16), and also controls supply air fan 39 to operate at a first supply airflow rate (S17).

[0085] If the result of the judgment in S15 is that the set ventilation intensity is "medium" (S15: "medium"), the control unit 42 controls the exhaust fan 40 to operate at the second exhaust airflow rate (S18) and also controls the supply air fan 39 to operate at the second supply airflow rate (S19).

[0086] If the result of the judgment in S15 is that the set ventilation intensity is "weak" (S15: "weak"), the control unit 42 controls the exhaust fan 40 to operate at the third exhaust airflow rate (S20) and also controls the supply air fan 39 to operate at the third supply airflow rate (S21).

[0087] Here, the first exhaust airflow rate, the second exhaust airflow rate, and the third exhaust airflow rate are set so that the airflow rates decrease in this order, and all of the exhaust airflow rates are set within a predetermined airflow rate range for heat exchange in the heat exchange type ventilation device 3. In other words, the first exhaust airflow rate, the second exhaust airflow rate, and the third exhaust airflow rate are suppressed to a level that does not reduce heat exchange efficiency. As a result, the ventilation system 1 exhausts air from the room 61 according to the ventilation intensity set by the user, and can perform sufficient heat exchange between the exhaust air and the supply air even when set to the maximum ventilation intensity ("strong").

[0088] The first, second, and third supply air volumes are set in this order to decrease, and each supply air volume is set within a predetermined range for heat exchange in the heat exchange type ventilation device 3. That is, the first, second, and third supply air volumes are controlled to a level that does not reduce heat exchange efficiency. This allows the ventilation system 1 to supply air from the outside 64 according to the ventilation intensity set by the user, while still achieving sufficient heat exchange between the exhaust air and the supply air, even when set to the maximum ventilation intensity ("strong").

[0089] When the control unit 42 completes the process of S17, S19, or S21, it ends the process of the normal air supply / exhaust mode and returns to the process of S1 of ventilation control (see FIG. 4).

[0090] Next, the emergency air supply / exhaust mode (S4) will be described. In the emergency air supply / exhaust mode (S4), if the exhaust air duct was set to exhaust air duct 5 in the normal air supply / exhaust mode (S3) that was executed immediately before, the emergency air supply / exhaust mode (S4) continues to use exhaust air duct 5 to exhaust refrigerant that has leaked into the room 61. In addition, in the emergency air supply / exhaust mode (S4), if the exhaust air duct was set to bypass exhaust air duct 6 in the normal air supply / exhaust mode (S3) that was executed immediately before, the emergency air supply / exhaust mode (S4) continues to use bypass exhaust air duct 6 to exhaust refrigerant that has leaked into the room 61.

[0091] In this way, when transitioning from the normal air supply / exhaust mode (S3) to the emergency air supply / exhaust mode (S4), the exhaust air passage switching unit 41 does not switch the air passage for the exhaust air, so the ventilation system 1 does not need to stop the exhaust fan 40. Therefore, the ventilation system 1 can quickly perform the initial operation of discharging the refrigerant that has leaked from the air conditioner 2 into the room 61, and thereby discharge the refrigerant to the outside 64 in a short time.

[0092] In the emergency air supply / exhaust mode (S4), as shown in FIG. 6, the control unit 42 instructs the ventilation remote controller 65 to execute a predetermined notification (S31).

[0093] Here, while the emergency air supply / exhaust mode (S4) is being executed, control unit 42 does not accept the setting of the ventilation intensity even if the user sets the setting on ventilation remote controller 65. In other words, when exhaust fan 40 and air supply fan 39 are operating in the emergency air supply / exhaust mode (S4), even if the user sets the ventilation intensity on ventilation remote controller 65, the airflow rates of exhaust fan 40 and air supply fan 39 are not changed based on the setting.

[0094] As a result, even if the user accidentally operates ventilation remote controller 65 to change the ventilation intensity while exhaust fan 40 is operating in emergency air supply / exhaust mode (S4), exhaust fan 40 and air supply fan 39 will operate at the air volume set in emergency air supply / exhaust mode (S4). Therefore, ventilation system 1 can reliably discharge refrigerant that has leaked into room 61 to outside room 64, regardless of the operation of ventilation remote controller 65 by the user.

[0095] The predetermined notification instructed by the processing of S31 notifies the user that the ventilation intensity setting by the ventilation remote controller 65 is invalid. The ventilation remote controller 65 executes the predetermined notification based on an instruction to execute the predetermined notification from the control unit 42. Methods of the predetermined notification include, but are not limited to, displaying a character string on a liquid crystal display provided on the ventilation remote controller 65, notifying by voice, and turning on or blinking a predetermined light-emitting diode.

[0096] The predetermined notification continues until the control unit 42 determines that the emergency air supply / exhaust mode (S4) has ended and instructs the ventilation remote controller 65 to end the predetermined notification. Note that the ventilation remote controller 65 may be configured to issue the predetermined notification only if the user attempts to set the ventilation intensity using the ventilation remote controller 65 during the period instructed by the control unit 42 to issue the predetermined notification.

[0097] Next, the control unit 42 acquires the refrigerant concentration Cr in the air duct inside the indoor unit 21 of the air conditioner 2, which is included in the detection information transmitted from the refrigerant sensor 24, via the acquisition unit 43. The control unit 42 also acquires the refrigerant concentration Ce contained in the air (i.e., return air (RA)) sucked into the heat exchanger ventilation device 3 from the indoor space 61, from the exhaust refrigerant sensor 71 (S32). The refrigerant concentration Cr makes it possible to determine the state of refrigerant leakage from the air conditioner 2. The refrigerant concentration Ce also makes it possible to determine how well the heat exchanger ventilation device 3 is sucking the refrigerant from the indoor space 61.

[0098] The control unit 42 then determines whether the refrigerant concentration Ce is less than a predetermined exhaust threshold and whether the refrigerant concentration Cr is equal to or greater than a predetermined concentration threshold (S33). As a result, if it is determined that the refrigerant concentration Ce is equal to or greater than the predetermined exhaust air volume or the refrigerant concentration Cr is less than the predetermined concentration threshold (S33: No), the control unit 42 executes the processes of S34 and S35. Here, when the refrigerant concentration Ce is equal to or greater than the predetermined exhaust air volume, it means that the heat exchange type ventilation device 3 is successfully drawing refrigerant from the room 61. Furthermore, when the refrigerant concentration Cr is less than the predetermined concentration threshold, it means that the refrigerant concentration in the room 61 is becoming low.

[0099] In this case, the control unit 42 controls the exhaust fan 40 to operate at a fourth exhaust airflow rate (S34) and the supply fan 39 to operate at a fourth supply airflow rate (S35). Here, the fourth exhaust airflow rate is greater than the first exhaust airflow rate. That is, in the emergency supply / exhaust mode (S4), the heat exchange efficiency is ignored, and the exhaust fan 40 is operated at an airflow rate greater than the first exhaust airflow rate, which is the maximum airflow rate set in the airflow rate range (first exhaust airflow rate, second exhaust airflow rate, third exhaust airflow rate) of the normal supply / exhaust mode (S3), in order to quickly exhaust the refrigerant that has leaked into the room 61. This allows the ventilation system 1 to quickly exhaust the refrigerant that has leaked from the air conditioner 2 into the room 61 at a large exhaust airflow rate, even if the first exhaust airflow rate is kept low to allow heat exchange between the exhaust air and the supply air. The fourth exhaust airflow rate may be set, for example, to the maximum airflow rate that the exhaust fan 40 is capable of (i.e., the maximum airflow rate that can be set for the exhaust fan 40). The fourth exhaust airflow rate may be set to a predetermined multiple (for example, 1.2 times) of the first exhaust airflow rate.

[0100] The fourth supply airflow rate is greater than the first supply airflow rate. That is, in the emergency supply / exhaust mode (S4), the supply air fan 39 is operated at an airflow rate greater than the first supply airflow rate, which is the maximum airflow rate set in the airflow rate range (first supply airflow rate, second supply airflow rate, third supply airflow rate) of the normal supply / exhaust mode (S3), for the purpose of quickly discharging refrigerant that has leaked into the room 61, without regard to heat exchange efficiency. This allows the ventilation system 1 to prevent excessive negative pressure in the room 61 and facilitate the discharge of refrigerant to the outside 64, even if the first supply airflow rate is kept low to allow heat exchange between the exhaust air and the supply air. Furthermore, since the ventilation system 1 can actively take in fresh air (outside air) from the outside 64, it can dilute the concentration Cr of the refrigerant in the room 61. The fourth supply airflow rate may be set, for example, to the maximum airflow rate that the supply air fan 39 is capable of (i.e., the maximum airflow rate that can be set for the supply air fan 39). The fourth supply air flow rate may be set to a predetermined multiple (for example, 1.2 times) of the first supply air flow rate.

[0101] The fourth exhaust airflow rate and the fourth supply airflow rate may both be set to the maximum airflow rate that the exhaust fan 40 or the supply airflow fan 39 has as its capacity, or one of them may be set to the maximum airflow rate that the corresponding fan has as its capacity, and the other may be set to an airflow rate that is less than the capacity of the corresponding fan.

[0102] Furthermore, when the exhaust air duct in heat exchange type ventilation device 3 is bypass exhaust duct 6, the air volume of exhaust fan 40 set by the process of S34 may be set to the same as the maximum air volume set in the air volume range of normal air supply / exhaust mode (S3). In this case, the air volume of supply fan 39 set by the process of S35 may be set to the same as the maximum air volume set in the air volume range of normal air supply / exhaust mode (S3).

[0103] When the normal air supply / exhaust mode (S3) is executed in the bypass exhaust air duct 6, heat exchange between the exhaust air and the intake air does not occur, so the maximum airflow rates of the exhaust fan 40 and the intake fan 39 can be set high. Therefore, in this case, even if the airflow rate of the exhaust fan 40 set by the processing of S34 is the same as the maximum airflow rate set within the airflow rate range of the normal air supply / exhaust mode (S3), the refrigerant leaking from the air conditioner 2 into the room 61 can be quickly discharged with a large exhaust airflow rate. Furthermore, even if the airflow rate of the intake fan 39 set by the processing of S35 is the same as the maximum airflow rate set within the airflow rate range of the normal air supply / exhaust mode (S3), the large intake airflow rate can prevent the room 61 from becoming excessively negative pressure. Furthermore, a large amount of fresh air from the outside 64 is taken into the room 61.

[0104] On the other hand, if it is determined in S33 that the refrigerant concentration Ce is less than the predetermined exhaust threshold and the refrigerant concentration Cr is equal to or greater than the predetermined concentration threshold (S33: Yes), the control unit 42 executes the process of S36. Here, the case where the refrigerant concentration Ce is less than the predetermined exhaust threshold and the refrigerant concentration Cr is equal to or greater than the predetermined concentration threshold means that refrigerant remains in the room 61 and the heat exchange type ventilation device 3 is not successfully drawing the refrigerant from the room 61. In particular, since refrigerant is generally heavier than air, there may be cases where the ventilation system 1 alone is unable to discharge the refrigerant that has leaked into the room 61.

[0105] In such a case, the control unit 42 controls the exhaust fan 40 to operate at a fifth exhaust airflow rate (S36). The fifth exhaust airflow rate is an airflow rate at which the exhaust airflow rate (EA) from the exhaust fan 40 is less than the airflow rate of the supply air (SA) from the supply air fan 39 operating at the fourth supply airflow rate. In other words, the processing of S36 causes the airflow rate of the supply air (SA) to be greater than the airflow rate of the exhaust air (EA). As a result, the interior of the room 61 becomes positive pressure, and the refrigerant accumulated in the lower part of the room 61 can be discharged to the outside 64 through a gap at the bottom of the room 61 and a louver 66 provided at the bottom of the room 61.

[0106] In the process of S36, the air volume of the supply air (SA) from the heat exchange type ventilation device 3 should be set to be larger than the air volume of the exhaust air (EA). For example, as long as this condition is met, the control unit 42 may increase the air volume of the supply air fan 39 while maintaining the air volume of the exhaust fan 40, or may change the air volumes of both the exhaust fan 40 and the supply air fan 39. However, it is preferable to set the supply air volume of the supply air fan 39 as large as possible.

[0107] Furthermore, the determination in S33 may not be made for a predetermined period of time after the emergency air supply / exhaust mode is started (i.e., a predetermined period of time after the refrigerant concentration Cr in the air duct inside the indoor unit 21 of the air conditioner 2 transitions from a state where it is below a predetermined concentration threshold to a state where it is equal to or greater than the predetermined concentration threshold). This is because, during that predetermined period, the exhaust by the exhaust fan 40 at the fourth exhaust airflow rate in the emergency air supply / exhaust mode (S4) may not be stable, and the determination in S33 may not be made correctly. Therefore, the control unit 42 may skip the determination in S33 and proceed to the process of S34 after the process of S32, at least until the exhaust by the exhaust fan 40 at the fourth exhaust airflow rate has stabilized.

[0108] Upon completing the processing of S35 or S36, the control unit 42 again acquires the refrigerant concentration Cr in the air duct inside the indoor unit 21 of the air conditioner 2, which is included in the detection information transmitted from the refrigerant sensor 24, via the acquisition unit 43 (S37). The control unit 42 then determines whether the acquired refrigerant concentration Cr is less than a predetermined concentration threshold (S38). Note that the determination in S38 may be made using the refrigerant concentration Cr acquired by the processing of S32, without performing the processing of S37.

[0109] If the result of the determination in S38 is that the refrigerant concentration Cr is equal to or greater than the predetermined concentration threshold (S38: No), the control unit 42 resets the post-discharge elapsed time te measured by the timer unit 49 to zero (S39) and returns to the process of S32. On the other hand, if the result of the process in S38 is that the refrigerant concentration Cr is less than the predetermined concentration threshold, the control unit 42 updates the post-discharge elapsed time te measured by the timer unit 49 (S41). This allows the timer unit 49 to measure the post-discharge elapsed time te, which is the time elapsed since the refrigerant concentration Cr detected by the refrigerant sensor 24 transitioned from a state equal to or greater than the predetermined concentration threshold to a state below the predetermined concentration threshold. Then, based on this post-discharge elapsed time te, the control unit 42 can determine the elapsed time since it is estimated that the refrigerant leaked into the room 61 was successfully discharged to the outside 64 in the emergency air supply / exhaust mode (S4).

[0110] Therefore, the control unit 42 determines whether the elapsed time since discharge te is equal to or greater than a predetermined time threshold (S41). As a result, if it is determined that the elapsed time since discharge te is less than the predetermined time threshold (S41: No), the control unit 42 returns to the process of S32 and continues the emergency air supply / exhaust mode (S4).

[0111] On the other hand, if the result of the judgment in S41 is that the elapsed time since discharge te is equal to or greater than the predetermined time threshold (S41: Yes), the control unit 42 instructs the ventilation remote controller 65 to end the predetermined notification (S42) and transitions to the normal air supply / exhaust mode (S3).

[0112] By making the determination in S41, the ventilation system 1 can continue the emergency air supply / exhaust mode (S4) until the elapsed time since discharge te reaches or exceeds the predetermined time threshold, even if the refrigerant concentration Cr in the air duct inside the indoor unit 21 of the air conditioner 2 falls below a predetermined concentration threshold. Then, only when it is determined that the refrigerant in the room 61 has been reliably discharged to the outside 64 and that the refrigerant leakage from the air conditioner 2 has also subsided, can the ventilation system 1 switch from the emergency air supply / exhaust mode (S4) to the normal air supply / exhaust mode (S3). Thus, the ventilation system 1 can reliably ensure the safety of the room 61.

[0113] Furthermore, by the processing of S42, ventilation remote controller 65 ends the notification that the ventilation intensity setting by ventilation remote controller 65 is invalid. Then, with the transition to the normal air supply / exhaust mode (S3), control unit 42 accepts the ventilation intensity setting by ventilation remote controller 65, and sets the air volume of exhaust fan 40 and the air volume of air supply fan 39 based on the setting.

[0114] (Disclosure Summary) A ventilation system 1 according to one embodiment of the present disclosure ventilates an indoor room 61 conditioned by an air conditioner 2, and includes a heat exchanger-type ventilation device 3 including an intake air duct 4, an exhaust air duct 5, an intake fan 39, an exhaust fan 40, an acquisition unit 43, and a control unit 42. The heat exchanger-type ventilation device 3 exchanges heat between exhaust air flowing from the indoor room 61 to the outdoor room 64 and intake air flowing from the outdoor room 64 to the indoor room 61 using a heat exchange element 38. The intake air duct 4 connects the outdoor room 64 to the indoor room 61 via the heat exchange element 38. The exhaust air duct 5 connects the indoor room 61 to the outdoor room 64 via the heat exchange element 38. The intake fan 39 guides the intake air into the indoor room 61 via the intake air duct 4. The exhaust fan 40 guides the exhaust air to the outdoor room 64 via the exhaust air duct 5. The acquisition unit 43 acquires detection information from a refrigerant sensor 24 that detects refrigerant leakage from the air conditioner 2. The control unit 42 has a normal air supply / exhaust mode (S3) and an emergency air supply / exhaust mode (S4). In the normal air supply / exhaust mode (S3), the exhaust fan 40 operates within a predetermined air volume range for heat exchange in the heat exchange type ventilation device 3. In the emergency air supply / exhaust mode (S4), when it is determined that the refrigerant concentration Cr detected by the refrigerant sensor 24 is equal to or greater than a predetermined concentration threshold based on the detection information acquired by the acquisition unit 43, the exhaust fan 40 operates at an air volume greater than the maximum air volume set within the air volume range of the normal air supply / exhaust mode (S3).

[0115] According to the ventilation system 1 of this embodiment, in the normal air supply / exhaust mode (S3), the control unit 42 controls the exhaust fan 40 to operate within a predetermined air volume range for heat exchange in the heat exchange type ventilation device 3. This allows the ventilation system 1 to perform sufficient heat exchange between the exhaust air and the intake air. On the other hand, if the control unit 42 determines that the refrigerant concentration Cr detected by the refrigerant sensor 24 is equal to or greater than the predetermined concentration threshold, the control unit 42 executes the emergency air supply / exhaust mode (S4). In this emergency air supply / exhaust mode (S4), the control unit 42 controls the exhaust fan 40 to operate at an air volume greater than the maximum air volume set within the air volume range of the normal air supply / exhaust mode (S3). This has the effect of allowing the ventilation system 1 to quickly discharge refrigerant leaking from the air conditioner 2 into the room 61.

[0116] In the normal air supply / exhaust mode (S3), the control unit 42 operates the air supply fan 39 within a predetermined air volume range for heat exchange in the heat exchange type ventilation device 3, and in the emergency air supply / exhaust mode (S4), if it determines that the refrigerant concentration Cr detected by the refrigerant sensor 24 based on the detection information acquired by the acquisition unit 43 is equal to or greater than a predetermined concentration threshold, it may operate the air supply fan 39 at an air volume greater than the maximum air volume set in the air volume range of the normal air supply / exhaust mode (S3).

[0117] As a result, in the normal air supply / exhaust mode (S3), the control unit 42 controls the supply air fan 39 to operate within a predetermined airflow range for heat exchange in the heat exchange type ventilation device 3. Therefore, the ventilation system 1 can perform sufficient heat exchange between the exhaust air and the supply air. Meanwhile, in the emergency air supply / exhaust mode (S4), which is executed when it is determined that the refrigerant concentration Cr detected by the refrigerant sensor 24 is equal to or greater than a predetermined concentration threshold, the control unit 42 controls the supply air fan 39 to operate at an airflow rate greater than the maximum airflow rate set for the airflow rate range in the normal air supply / exhaust mode (S3). That is, when it is determined that there is a refrigerant leak from the air conditioner 2, the airflow rates of not only the exhaust fan 40 but also the supply air fan 39 are set to be greater than the maximum airflow rate set in the normal air supply / exhaust mode (S3). This allows the ventilation system 1 to prevent excessive negative pressure in the room 61 and facilitate the discharge of the refrigerant to the outside 64. Furthermore, since fresh air (outside air) from the outside 64 can be actively taken in, the ventilation system 1 has the effect of being able to dilute the concentration Cr of the refrigerant in the room 61.

[0118] In this case, the ventilation system 1 may further include an exhaust refrigerant sensor 71 that detects the concentration Ce of refrigerant contained in the air drawn into the heat exchange type ventilation device 3 from the indoors 61. When it is determined that the refrigerant concentration Ce detected by the exhaust refrigerant sensor 71 is less than a predetermined exhaust threshold and that the refrigerant concentration Cr detected by the refrigerant sensor 24 is equal to or greater than the predetermined concentration threshold based on the detection information acquired by the acquisition unit 43, the control unit 42 may make the air volume of the supply air (SA) greater than the air volume of the exhaust air (EA).

[0119] If the refrigerant concentration Ce detected by the exhaust refrigerant sensor 71 is less than the predetermined exhaust threshold, and if it is determined based on the detection information acquired by the acquisition unit 43 that the refrigerant concentration Cr detected by the refrigerant sensor 24 is equal to or greater than the predetermined concentration threshold, this means that the heat exchange type ventilation device 3 is not successfully drawing in the refrigerant from the room 61. In this case, by controlling the air volume of the supply air (SA) to be greater than the air volume of the exhaust air (EA), the room 61 becomes positive pressure, which has the effect of allowing the refrigerant accumulated in the room 61 to be discharged to the outside 64 through gaps in the room 61.

[0120] The ventilation system 1 may further include a timer unit 49 that measures a post-discharge elapsed time te, which is the time that has elapsed since the refrigerant concentration Cr detected by the refrigerant sensor 24 transitioned from a state where the refrigerant concentration Cr was equal to or greater than a predetermined concentration threshold to a state where the refrigerant concentration Cr was less than the predetermined concentration threshold, based on the detection information acquired by the acquisition unit 43. When the post-discharge elapsed time te measured by the timer unit 49 is equal to or greater than the predetermined time threshold and the exhaust fan 40 is exhausting in the emergency air supply / exhaust mode (S4), the control unit 42 may control the exhaust fan 40 to switch from the emergency air supply / exhaust mode (S4) to the normal air supply / exhaust mode (S3).

[0121] As a result, when the ventilation system 1 is in the emergency air supply / exhaust mode (S4), it does not immediately switch to the normal air supply / exhaust mode (S3) when the refrigerant concentration Cr transitions from a state equal to or greater than a predetermined concentration threshold to a state below the predetermined concentration threshold, but switches to the normal air supply / exhaust mode (S3) when the elapsed time te since the transition reaches or exceeds a predetermined time threshold. Thus, the ventilation system 1 can switch to the normal air supply / exhaust mode (S3) only when it is determined that the refrigerant in the room 61 has been reliably discharged to the outside 64 and that the refrigerant leakage from the air conditioner 2 has also been contained. Therefore, the ventilation system 1 has the effect of reliably ensuring the safety of the room 61.

[0122] The ventilation system 1 may further include a ventilation remote controller 65 that enables a user of the heat exchange type ventilation device 3 to set a specific air volume within a predetermined air volume range of the exhaust fan 40. The control unit 42 may be configured not to accept settings from the ventilation remote controller 65 when the exhaust fan 40 is operating in the emergency air supply / exhaust mode (S4).

[0123] As a result, even if the user mistakenly operates the ventilation remote controller 65 to set the air volume of the exhaust fan 40 to a specific air volume while the exhaust fan 40 is operating in the emergency air supply / exhaust mode (S4), the exhaust fan 40 will operate at the air volume set in the emergency air supply / exhaust mode (S4). Therefore, the ventilation system 1 has the effect of reliably discharging refrigerant that has leaked into the room 61 to the outside 64, regardless of the operation of the ventilation remote controller 65 by the user.

[0124] Although the present disclosure has been described above based on the embodiments, it is readily apparent that the present disclosure is not limited to the above embodiments and that various improvements and modifications are possible within the scope of the present disclosure. For example, each of the embodiments, including the modifications described in the above embodiments and the modifications described below, may be modified by adding or replacing a part or parts of the configuration of another embodiment with the other embodiment. Furthermore, the numerical values ​​given in each embodiment are merely examples, and other numerical values ​​may of course be adopted.

[0125] In the above embodiment, the ventilation system 1 has been described as having, as an air passage for exhausting air, the exhaust air passage 5 that passes through the heat exchange element 38 and the bypass exhaust air passage 6 that does not pass through the heat exchange element 38. In contrast, the ventilation system 1 may have, as an air passage for exhausting air, only the exhaust air passage 5 that passes through the heat exchange element 38, without the bypass exhaust air passage 6. In this case, the ventilation system 1 uses the exhaust air passage 5 to exhaust air while exchanging heat with the supply air flowing through the supply air passage 4, regardless of the temperature Ti of the room 61 and the temperature To of the outside room 64. The present disclosure is also applicable to a ventilation system 1 configured in this way.

[0126] In the above embodiment, a case has been described in which exhaust fan 40 is set to the fourth exhaust airflow rate and intake fan 39 is set to the fourth intake airflow rate in emergency intake and exhaust mode (S4), but exhaust fan 40 may be set to the fourth exhaust airflow rate and intake fan 39 to the first intake airflow rate (i.e., the maximum airflow rate set in normal intake and exhaust mode (S3)). Although there is a risk of negative pressure in room 61, at least a large exhaust airflow rate that ignores heat exchange efficiency allows refrigerant that has leaked from air conditioner 2 into room 61 to be quickly discharged. [Industrial Applicability]

[0127] INDUSTRIAL APPLICABILITY The ventilation system according to the present invention is useful as a ventilation system that can ventilate a room conditioned by an air conditioner and also discharge refrigerant that has leaked from the air conditioner into the room to the outside. [Explanation of symbols]

[0128] 1. Ventilation system 2. Air conditioners 3. Heat exchange ventilation system 4 Air supply duct 5 Exhaust air duct 6 Bypass exhaust air duct 21 Indoor unit 22 Outdoor unit 23 Air conditioning control unit 24 Refrigerant sensor 25 Air conditioner remote controller 31 Fresh air intake 32 Air supply outlet 33 In-device air supply duct 34 Return air intake 35 Exhaust outlet 36 Exhaust air duct inside the device 37 In-device bypass exhaust air duct 38 Heat exchange element 39 Intake fan 40 Exhaust fan 41 Exhaust air path switching section 42 Control Unit 43 Acquisition Department 45 Outdoor temperature sensor 46 Indoor temperature sensor 47 Return air filter 48 Outdoor air filter 49 Timer section 51 Outdoor air intake 52 Indoor air outlet 53 Outdoor air duct 54 Air supply duct 55 Indoor air intake 56 Outdoor outlet 57 Return air duct 58 Exhaust duct 62 Attic 63 Ceiling 64 Outdoors 65 Ventilation remote controller 66 Garari 71 Exhaust refrigerant sensor EA Exhaust OA Outside air RA return air SA Air Supply

Claims

1. A ventilation system using a heat exchange type ventilation device that exchanges heat between exhaust air flowing from a room conditioned by an air conditioner to the outside of the room and supply air flowing from the outside of the room to the room using a heat exchange element, an air supply passage that connects the outside of the room with the inside of the room via the heat exchange element; an exhaust air duct that connects the indoor space with the outdoor space via the heat exchange element; an air supply fan that guides the supply air into the room through the air supply duct; an exhaust fan that guides the exhaust air to the outside of the room through the exhaust air duct; an acquisition unit that acquires detection information from a refrigerant sensor that detects refrigerant leakage from the air conditioner; a control unit, The control unit a normal exhaust mode in which the exhaust fan is operated within a predetermined air volume range for heat exchange in the heat exchange type ventilation device; an emergency exhaust mode that operates the exhaust fan at an airflow rate greater than the maximum airflow rate set within the airflow range of the normal exhaust mode when it is determined that the refrigerant concentration detected by the refrigerant sensor is equal to or greater than a predetermined concentration threshold based on the detection information acquired by the acquisition unit.

2. The control unit a normal air supply mode in which the air supply fan is operated within a predetermined air volume range for heat exchange in the heat exchange type ventilation device; 2. The ventilation system of claim 1, further comprising an emergency air supply mode that operates the air supply fan at an air volume greater than the maximum air volume set in the air volume range of the normal air supply mode when it is determined that the refrigerant concentration detected by the refrigerant sensor is equal to or greater than a predetermined concentration threshold based on the detection information acquired by the acquisition unit.

3. The ventilation system further includes an exhaust refrigerant sensor that detects the concentration of the refrigerant contained in the air drawn into the heat exchange type ventilation device from the indoors, The control unit 3. The ventilation system of claim 2, wherein when the concentration of the refrigerant detected by the exhaust refrigerant sensor is less than a predetermined exhaust threshold and when it is determined based on the detection information acquired by the acquisition unit that the concentration of the refrigerant detected by the refrigerant sensor is equal to or greater than a predetermined concentration threshold, the air volume of the supply air is made greater than the air volume of the exhaust air.

4. a timer unit configured to measure an elapsed time after discharge, which is an elapsed time since the refrigerant concentration detected by the refrigerant sensor based on the detection information acquired by the acquisition unit has transitioned from a state in which the refrigerant concentration is equal to or greater than a predetermined concentration threshold to a state in which the refrigerant concentration is less than the predetermined concentration threshold; The control unit 2. The ventilation system of claim 1, wherein when the elapsed time since discharge measured by the timer unit is equal to or greater than a predetermined time threshold and the exhaust fan is exhausting in the emergency exhaust mode, the exhaust fan is controlled to switch from the emergency exhaust mode to the normal exhaust mode.

5. a remote controller for allowing a user of the heat exchange type ventilation device to set a specific air volume within the predetermined air volume range of the exhaust fan; The control unit The ventilation system according to claim 1 , wherein when the exhaust fan is operating in the emergency exhaust mode, settings from the remote controller are not accepted.

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