Ventilation system

Abstract

To provide a ventilation system capable of discharging a refrigerant to an outdoor side for a short time by promptly performing initial action of discharging the refrigerant leaked from an air conditioner to an indoor side.SOLUTION: A heat exchange type ventilation device 3 exchanges heat between exhaust air flowing from an indoor side to an outdoor side and supply air flowing from the outdoor side to the indoor side by using a heat exchange element 38. An air supply air course 4 communicates the outdoor side and the indoor side via the heat exchange element 38. A heat exchange air exhaust air course 5 communicates the indoor side and the outdoor side via the heat exchange element 38. A bypass air exhaust air course 6 communicates the indoor side and the outdoor side without interposing the heat exchange element 38. An air exhaust air course switching section 41 switches the heat exchange air exhaust air course 5 and the bypass air exhaust air course on the basis of an indoor temperature and an outdoor temperature. A control section stops control of switching by the air exhaust air course switching section 41 when determining that a concentration of a refrigerant indicating leakage of the refrigerant from an air conditioner detected by a refrigerant sensor is a predetermined concentration threshold value or larger.SELECTED DRAWING: Figure 2

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] The ventilation system described in Patent Document 1 is configured to be able to switch between "an air duct that exhausts indoor air via a total heat exchanger" and "an air duct that exhausts indoor air without passing through a total heat exchanger" using an exhaust opening / closing mechanism (damper). When a refrigerant leak from an air conditioner is detected indoors, this ventilation system operates the damper to switch to "an air duct that exhausts indoor air without passing through a total heat exchanger," thereby discharging the refrigerant in a short period of time. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2020-186820 Summary of the Invention [Problem to be solved by the invention]

[0006] However, when the damper is operated, the exhaust fan must be stopped to prevent damage to the damper due to excessive load. In other words, when a refrigerant leak is detected in the air conditioner, the exhaust fan must be stopped temporarily in order to switch the damper to an air path that exhausts indoor air without passing through the total heat exchanger, which causes a delay in the initial discharge of the refrigerant.

[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 to the outside in a short period of time by quickly performing the initial discharge of the refrigerant. [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, a heat exchanger exhaust air duct, a bypass exhaust air duct, an intake fan, an exhaust fan, an exhaust air duct switching unit, an acquisition unit, and a control unit. The heat exchanger 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 heat exchanger exhaust air duct connects the room to the outside via the heat exchange element. The bypass exhaust air duct connects the room to the outside without passing through 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 heat exchanger exhaust air duct or the bypass exhaust air duct. The exhaust airflow path switching unit switches between the heat exchanger exhaust airflow path and the bypass exhaust airflow path based on the indoor and outdoor temperatures. The acquisition unit acquires detection information from a refrigerant sensor that detects refrigerant leakage from the air conditioner. The control unit stops control of the switching by the exhaust airflow path switching unit when it determines, based on the detection information acquired by the acquisition unit, that the refrigerant concentration detected by the refrigerant sensor is equal to or greater than a predetermined concentration threshold. [Effects of the Invention]

[0009] According to the present disclosure, by quickly starting the discharge of refrigerant that has leaked from an air conditioner into the room, it is possible to effectively discharge the refrigerant to the outside of the room in a short period of time. [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 heat exchanger 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, a heat exchange exhaust air duct 5, a bypass exhaust air duct 6, an intake air fan 39, an exhaust fan 40, an exhaust air duct switching unit 41, an acquisition unit 43, a control unit 42, a timer unit 44, 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 heat exchanger 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 intake air outlet 32, a return air intake port 34, and an exhaust air outlet 35. The heat exchange type ventilation device 3 also has an internal intake air duct 33, an internal heat exchanger exhaust air duct 36, an internal bypass exhaust air duct 37, an outdoor temperature sensor 45, and an indoor temperature sensor 46 inside the housing.

[0022] The heat exchange element 38 is provided at the intersection of the intake air duct 4 and the heat exchanger exhaust air duct 5, which will be described later, and is an element in which the intake air ducts 4 and the heat exchanger exhaust air ducts 5 are alternately stacked with a heat transfer plate (not shown) sandwiched between them. The heat exchange element 38 exchanges heat and humidity (total heat exchange) between the intake air flowing through the intake air duct 4 and the exhaust air flowing through the heat exchanger exhaust air duct 5 via the heat transfer plate. Note that the heat exchange element 38 may also exchange only heat (sensible heat exchange) between the intake air flowing through the intake air duct 4 and the exhaust air flowing through the heat exchanger 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 a 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 heat exchanger exhaust air duct 36 is an air duct within the heat exchanger type ventilation device 3 that connects the return air inlet 34 and the exhaust air outlet 35 via a heat exchange element 38. The return air (RA) taken into the heat exchanger type ventilation device 3 from the return air inlet 34 can pass through the internal heat exchanger exhaust air duct 36 as exhaust air while passing through the heat exchange element 38 by an exhaust air duct switching unit 41, which will be described later. The exhaust air that has passed through the internal heat exchanger exhaust air duct 36 is blown out from the supply air outlet 32 ​​as exhaust air (EA).

[0031] The return air duct 57, the in-device heat exchanger exhaust air duct 36, and the exhaust duct 58 form the heat exchanger exhaust air duct 5. That is, the heat exchanger 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 heat exchanger exhaust air 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 air 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 heat exchange 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 the bypass exhaust air duct 6 does not pass through the heat exchange element 38, there is no pressure loss due to the heat exchange element 38. In addition, the internal bypass exhaust air duct 37 is not provided with a filter like the return air side filter 47 that is provided in the internal heat exchanger exhaust air duct 36. This is because the internal bypass exhaust air duct 37 does not have anything in the air duct that can cause clogging like the heat exchange element 38. Compared to the heat exchanger exhaust air duct 5, the bypass exhaust air duct 6 has the advantage of being able to reduce pressure loss due to the heat exchange element 38 and the return air side filter 47.

[0037] Furthermore, heat exchange element 38 cannot always completely separate intake air duct 4 and heat exchanger exhaust air duct 5 as ideally, and gaps may be formed that connect intake air duct 4 and heat exchanger exhaust air duct 5. This can cause some of the exhaust air flowing through heat exchanger exhaust air duct 5 to leak into intake air duct 4 via heat exchange element 38 and be blown out as intake air (SA) together with the intake air into room 61. If exhaust air is discharged 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 leaking into intake air duct 4 from being blown out into room 61 as intake 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 heat exchanger exhaust air duct 36). 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 inside the indoor space 61, a ventilation remote controller 65 provided in the indoor space 61, or 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 heat exchanger exhaust air duct 36 or the internal bypass exhaust air duct 37.

[0040] The ventilation remote controller 65 is an input interface that accepts settings related to the operation of the ventilation system 1 through user operation. For example, the ventilation strength (weak, medium, strong) in the ventilation system 1 is set by the user operating the ventilation remote controller 65. Note that the ventilation remote controller 65 may be realized by a mobile information terminal such as a smartphone that has an application that can make these settings.

[0041] The ventilation remote controller 65 is connected to the control unit 42 by wire or wirelessly. Setting information received by the ventilation remote controller 65 is transmitted to the control unit 42. The control unit 42 also instructs the ventilation remote controller 65 to issue various notifications. Based on the instructions, the ventilation remote controller 65 issues various notifications to people in the room 61.

[0042] Air supply fan 39 is provided in internal air supply duct 33, and is a fan for guiding outside air (OA) as supply air (SA) into room 61 via air supply duct 4. The air volume of air supply fan 39 is controlled by control unit 42. For example, during normal operation when no refrigerant leakage from air conditioner 2 is detected, control unit 42 controls the air volume of air supply fan 39 so that air is supplied at an air volume specified within a predetermined air volume range according to the ventilation intensity set by ventilation remote controller 65.

[0043] Furthermore, when a refrigerant leak from the air conditioner 2 is detected, the control unit 42 controls the air volume of the supply air fan 39 so as to supply air at the maximum air volume. This maximum air volume is the maximum air volume set for the supply air fan 39, and may be an air volume equal to or greater than the air volume that can be set for the supply air fan 39 under normal circumstances when a refrigerant leak from the air conditioner 2 is not detected, i.e., an air volume equal to or greater than the maximum air volume within the above-mentioned predetermined air volume range. Furthermore, the maximum air volume of the supply air fan 39 that is set when a refrigerant leak from the air conditioner 2 is detected may be the maximum air volume that the supply air fan 39 is capable of (i.e., the maximum air volume that can be set for the supply air fan 39).

[0044] The exhaust fan 40 is provided in an air duct that serves both as the internal heat exchanger exhaust air duct 36 and the internal bypass exhaust air duct 37, and is a fan that guides the return air (RA) as exhaust air (EA) to the outdoors 64 via the heat exchanger 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. For example, during normal operation when no refrigerant leakage from the air conditioner 2 is detected, the control unit 42 controls the air volume of the exhaust fan 40 so that air is exhausted 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, when a refrigerant leak from the air conditioner 2 is detected, the control unit 42 controls the air volume of the exhaust fan 40 so that air is exhausted at the maximum air volume. This maximum air volume is the maximum air volume set for the exhaust fan 40, and may be an air volume equal to or greater than the air volume that can be set for the exhaust fan 40 under normal circumstances when a refrigerant leak from the air conditioner 2 is not detected, i.e., an air volume equal to or greater than the maximum air volume within the above-mentioned predetermined air volume range. Furthermore, the maximum air volume of the exhaust fan 40 that is set when a refrigerant leak from the air conditioner 2 is detected may be the maximum air volume that the exhaust fan 40 is capable of (i.e., the maximum air volume that can be set for the exhaust fan 40).

[0046] The exhaust airflow path switching unit 41 is provided in the heat exchange type ventilation device 3, and is a damper that switches between the heat exchange 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.

[0047] Here, the role of the 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 the exhaust airflow path switching unit 41 has switched to the heat exchanger exhaust airflow path 5 as the airflow path for exhaust air flowing from the room 61 to the outside 64. Fig. 3(b) is a diagram showing a state in which the exhaust airflow path switching unit 41 has switched to the bypass exhaust airflow path 6 as the airflow path for exhaust air flowing from the room 61 to the outside 64.

[0048] The control unit 42 controls the exhaust airflow path switching unit 41 to switch between the heat exchanger exhaust airflow path 5 and the bypass exhaust airflow path 6 based on the temperature Ti of the indoor room 61 detected by the indoor temperature sensor 46 and the temperature To of the outdoor room 64 detected by the outdoor temperature sensor 45.

[0049] 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 heat exchanger exhaust airflow path 5, as shown in Fig. 3(a). As a result, heat exchange occurs between the exhaust air flowing through the heat exchanger exhaust airflow path 5 and the supply air flowing through the supply airflow path 4 by the heat exchange element 38, so that the temperature of the supply air (SA) can be brought close to the temperature Ti in the room 61 before being taken into the room 61, as described above.

[0050] 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 heat exchanger 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 air airflow path 4 from being blown into the room 61 as supply air (SA).

[0051] 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.

[0052] The timer unit 44 measures the time elapsed since leakage tr (see FIG. 6), which is the time that has elapsed since the refrigerant concentration Cr in the air duct of the indoor unit 21 of the air conditioner 2, detected by the refrigerant sensor 24, became equal to or greater than a predetermined concentration threshold. The time elapsed since leakage tr is referenced by the control unit 42 that is executing the emergency air supply / exhaust mode (S4), which will be described later. The control unit 42 performs control to switch to the bypass exhaust air duct 6 when the heat exchanger exhaust air duct 5 has been used to exhaust the refrigerant that has leaked into the room 61 for the time elapsed since leakage tr.

[0053] The control unit 42 controls the operation of the ventilation system 1. Information on the temperature Ti of the room 61 detected by the room temperature sensor 46, information on the temperature To of the outside room 64 detected by the outdoor temperature sensor 45, refrigerant leak detection information by the refrigerant sensor 24 acquired by the acquisition unit 43, the elapsed time since leakage tr measured by the timer unit 44, and setting information set for the ventilation remote controller 65 are input to the control unit 42. 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.

[0054] 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. 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 living room or a hallway different from the room 61.

[0055] 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.

[0056] 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.

[0057] 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).

[0058] If it is determined that the refrigerant concentration Cr is less than the predetermined concentration threshold value (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). When the control unit 42 finishes executing the normal air supply / exhaust mode (S3), it returns to the processing of S1.

[0059] On the other hand, if it is determined in S2 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). After completing execution of the emergency air supply / exhaust mode (S4), the control unit 42 switches to execution of the normal air supply / exhaust mode (S3).

[0060] 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.

[0061] 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).

[0062] As a result, if it is determined that the absolute value of the difference between the temperature Ti in the room 61 and the temperature To in the outdoor 64 is less than the predetermined temperature difference (S12: Yes), then the control unit 42 determines whether the current exhaust air path is the heat exchanger exhaust air path 5 (S13). As a result, if it is determined that the current exhaust air path is the heat exchanger exhaust air path 5 (S13: Yes), the control unit 42 temporarily stops the exhaust fan 40, switches the exhaust air path switching unit 41 so that the exhaust air path is the bypass exhaust air path 6 shown in FIG. 3(b) (S14), and proceeds to the process of S17. On the other hand, if the result of the process of S13 is that the current exhaust air path is the bypass exhaust air path 6 (S13: No), the control unit 42 proceeds directly to the process of S17.

[0063] Furthermore, if the result of the determination in S12 is 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), then the control unit 42 determines whether the current exhaust air path is the bypass exhaust air path 6 (S15). If the result of the determination is that the current exhaust air path is the bypass exhaust air path 6 (S15: Yes), the control unit 42 temporarily stops the exhaust fan 40, switches the exhaust air path switching unit 41 so that the exhaust air path is the heat exchanger exhaust air path 5 shown in FIG. 3(a) (S16), and proceeds to the process of S17. On the other hand, if the result of the process in S15 is that the current exhaust air path is the heat exchanger exhaust air path 5 (S15: No), the control unit 42 proceeds directly to the process of S17.

[0064] In the processing of S17, control unit 42 controls the air volume of exhaust air (EA) by exhaust fan 40 and the air volume of supply air (SA) by supply air fan 39 (S17) in accordance with the ventilation intensity set by ventilation remote controller 65. That is, control unit 42 controls the air volume of exhaust fan 40 so that exhaust air is exhausted at an air volume specified within a predetermined air volume range in accordance with the ventilation intensity, and also controls the air volume of supply air fan 39 so that air is supplied at an air volume specified within the predetermined air volume range.

[0065] After the process of S17, the control unit 42 ends the process of the normal air supply / exhaust mode, and returns to the process of S1 of the ventilation control (see FIG. 4).

[0066] In this way, exhaust airflow path switching unit 41 switches between heat exchanger exhaust airflow path 5 and bypass exhaust airflow path 6 so that the exhaust airflow path is an appropriate airflow path based on temperature Ti in the room 61 and temperature To in the outdoor 64. That is, if it is determined that the absolute value of the difference between temperature Ti in the room 61 and temperature To in the outdoor 64 is equal to or greater than a predetermined temperature difference (S12: No), the exhaust airflow path is set to heat exchanger exhaust airflow path 5 by the processes of S15 and S16. As a result, heat exchange is performed by heat exchange element 38 between exhaust air from the room 61 to the outdoor 64 and supply air from the outdoor 64 to the room 61, so that the temperature of supply air (SA) can be brought close to temperature Ti in the room 61 before being taken into the room 61.

[0067] On the other hand, if it is determined that the absolute value of the difference between the temperature Ti in the room 61 and the temperature To in the outdoor 64 is less than the predetermined temperature difference (S12: Yes), the processes of S13 and S14 set the exhaust air duct to the bypass exhaust air duct 6. As a result, when the temperature Ti in the room 61 and the temperature To in the outdoor 64 are close to each other, ventilation can be performed by increasing the exhaust air volume without performing heat exchange between the exhaust air and the intake air.

[0068] In the processes of S14 and S16, the control unit 42 temporarily stops the exhaust fan 40 because, if the exhaust airflow path switching unit 41 is operated while the exhaust is continuing, the exhaust puts a load on the exhaust airflow path switching unit 41, making the exhaust airflow path switching unit 41 more susceptible to failure. The control unit 42 can prevent failure of the exhaust airflow path switching unit 41 by temporarily stopping the exhaust fan 40 and switching the exhaust airflow path switching unit 41.

[0069] In the emergency air supply / exhaust mode (S4), as shown in Fig. 6, the control unit 42 first starts measuring the time elapsed since leakage tr (the time that has elapsed since the refrigerant concentration Cr became equal to or greater than the predetermined concentration threshold value as determined in S2 shown in Fig. 4) by the timer unit 44 (S21). Specifically, the control unit 42 resets the time elapsed since leakage tr and causes the timer unit 44 to start measuring the time elapsed since leakage tr (S21).

[0070] Next, the control unit 42 stops the control of the exhaust airflow path switching by the exhaust airflow path switching unit 41, and then controls the airflow of the exhaust fan 40 to the maximum, and also controls the airflow of the supply air fan 39 to the maximum (S22).

[0071] As a result, when it is determined that there is a refrigerant leak from the air conditioner 2 into the room 61, the exhaust air duct switching unit 41 does not switch the exhaust air duct, and if the exhaust air duct is the heat exchanger exhaust air duct 5, the exhaust air duct is maintained in the heat exchanger exhaust air duct 5 and the airflow rate of the exhaust fan 40 is maximized. Also, if the exhaust air duct is the bypass exhaust air duct 6, the exhaust air duct is maintained in the bypass exhaust air duct 6 and the airflow rate of the exhaust fan 40 is maximized. Therefore, when the emergency air supply / exhaust mode is entered, the exhaust fan 40 is not stopped in conjunction with switching the exhaust air duct. Therefore, the ventilation system 1 can quickly start discharging 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 period of time.

[0072] In this case, the air volume of the exhaust fan 40 is controlled to the maximum, and the air in the room 61 is exhausted to the outside 64 at that maximum air volume, so that the ventilation system 1 can discharge the refrigerant to the outside 64 in a short time.

[0073] In this case, by maximizing the airflow rate of the exhaust fan 40 and also maximizing the airflow rate of the supply air fan 39, it is possible to prevent the pressure in the room 61 from becoming too negative, and to make it easier to discharge the refrigerant to the outside 64. Furthermore, since fresh air (outside air OA) from the outside 64 can be actively taken in as supply air (SA), the ventilation system 1 can dilute the concentration Cr of the refrigerant in the room 61.

[0074] In the process of S22, the control unit 42 preferably controls the air volumes of the exhaust fan 40 and the supply air fan 39 so that the air volume of the supply air (SA) is greater than the air volume of the exhaust air (EA). Because 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. By making the air volume of the supply air (SA) greater than the air volume of the exhaust air (EA), the room 61 becomes positive pressure, and the refrigerant that has 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 or through a louver 66 provided at the bottom of the room 61.

[0075] Next, the control unit 42 again acquires, via the acquisition unit 43, the current 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 (S23). Then, the control unit 42 determines whether the refrigerant concentration Cr is less than a predetermined concentration threshold value (S24).

[0076] As a result, if it is determined that the refrigerant concentration Cr is less than the predetermined concentration threshold (S24: Yes), the control unit 42 terminates the emergency air supply / exhaust mode (S4) assuming that the refrigerant in the room 61 has been discharged to the outside 64, and transitions to the normal air supply / exhaust mode (S3).

[0077] On the other hand, if the result of the judgment in S24 is that the refrigerant concentration Cr is equal to or greater than the predetermined concentration threshold (S24: No), the control unit 42 assumes that refrigerant that has leaked from the air conditioner 2 into the room 61 remains and continues the emergency supply and exhaust mode.

[0078] The predetermined concentration threshold used in the determination of S24 may be the same as the predetermined concentration threshold used in the determination of S2 shown in Fig. 4, or a value lower than the predetermined concentration threshold used in the determination of S2 may be used. If the predetermined concentration threshold used in the determination of S24 is a value lower than the predetermined concentration threshold used in the determination of S2 shown in Fig. 4, it is possible to make a stricter determination that the refrigerant in the room 61 has been discharged to the outside 64. Therefore, the safety of the room 61 can be reliably ensured.

[0079] Furthermore, the determination in S24 may be made not based on the current refrigerant concentration Cr but by measuring the time since discharge, which is the time since the refrigerant concentration Cr transitioned from a state equal to or greater than a predetermined concentration threshold to a state below the predetermined concentration threshold, and determining whether the time since discharge is equal to or greater than the predetermined time threshold. That is, when the time since discharge is equal to or greater than the predetermined time threshold, the control unit 42 may determine that the refrigerant in the room 61 has been discharged to the outside 64 and terminate the emergency air supply / exhaust mode (S4). This allows the emergency air supply / exhaust mode (S4) to be terminated when the time since discharge is equal to or greater than the predetermined time threshold and it can be determined that the refrigerant in the room 61 has definitely been discharged to the outside 64, thereby reliably ensuring the safety of the room 61.

[0080] If the determination result in S24 is that the emergency air supply / exhaust mode continues (S24: No), then the control unit 42 determines whether the current exhaust air path is the heat exchanger exhaust air path 5 (S25). If the determination result is that the current exhaust air path is the bypass exhaust air path 6 (S25: No), the control unit 42 returns to the process of S23. As a result, the refrigerant that has leaked into the room 61 is discharged to the outside 64 via the bypass exhaust air path 6.

[0081] On the other hand, if it is determined in S25 that the current exhaust air duct is the heat exchanger exhaust duct 5 (S25: Yes), the controller 42 then determines whether the time since leakage tr measured by the timer 44 is equal to or greater than a predetermined time threshold (S26). If the time since leakage tr is less than the predetermined time threshold (S26: No), the controller 42 returns to the process of S23. As a result, the refrigerant leaked into the room 61 is discharged to the outside 64 by the heat exchanger exhaust duct 5 while the time since leakage tr is less than the predetermined time threshold.

[0082] On the other hand, if it is determined in S26 that the time elapsed since the leakage tr is equal to or greater than the predetermined time threshold (S26: Yes), the control unit 42 temporarily stops the exhaust fan 40 and switches the exhaust air-path switching unit 41 so that the air path for the exhaust air becomes the bypass exhaust air path 6 shown in Fig. 3(b) (S27). Then, the control unit 42 proceeds to the process of S22, and again controls the air volume of the exhaust fan 40 to the maximum, and resumes discharging the refrigerant that has leaked into the room 61 to the outside 64.

[0083] As a result, if it is determined that there is a refrigerant leak from the air conditioner 2 and the refrigerant is initially discharged to the outdoors 64 through the heat exchanger exhaust air duct 5, once discharge through the heat exchanger exhaust air duct 5 has been performed to a certain extent, the ventilation system 1 can switch the discharge of the refrigerant to the outdoors 64 to the bypass exhaust air duct 6. As described above, the bypass exhaust air duct 6 can increase the volume of exhaust air compared to the heat exchanger exhaust air duct 5. Furthermore, when exhausting air through the heat exchanger exhaust air duct 5, some of the exhausted refrigerant may leak into the supply air duct 4 through the heat exchange element 38. In contrast, when exhausting air through the bypass exhaust air duct 6, the refrigerant drawn into the bypass exhaust air duct 6 is efficiently discharged to the outdoors 64 because it does not pass through the heat exchange element 38.

[0084] In this way, even if the refrigerant is initially discharged to the outside 64 through the heat exchanger exhaust air duct 5, once a certain amount of discharge has been performed, the ventilation system 1 can switch to the bypass exhaust air duct 6, which is easier to discharge. Therefore, even if an amount of refrigerant that cannot be discharged through the heat exchanger exhaust air duct 5 has leaked into the room 61, the ventilation system 1 can reliably discharge the refrigerant to the outside 64 by switching to the bypass exhaust air duct 6 midway.

[0085] In the determination of S26, in addition to determining whether the time elapsed since leakage tr is equal to or greater than the predetermined time threshold, the refrigerant concentration Cr at that time may be acquired from the acquisition unit 43, and a determination may also be made as to whether the refrigerant concentration Cr is equal to or greater than a second predetermined concentration threshold. Here, the second predetermined concentration threshold is set to a value greater than the predetermined concentration threshold used in the determination of S24.

[0086] In this case, if it is determined that the time elapsed since leakage tr is equal to or greater than the predetermined time threshold and that the refrigerant concentration Cr is equal to or greater than the second predetermined concentration threshold, the process proceeds to S27, where the exhaust air passage is switched to the bypass exhaust air passage 6. On the other hand, if it is determined that the time elapsed since leakage tr is less than the predetermined time threshold or that the refrigerant concentration Cr is less than the second predetermined concentration threshold, the process proceeds to S23, where the heat exchanger exhaust air passage 5 is maintained as the exhaust air passage. In other words, even if the time elapsed since leakage tr is equal to or greater than the predetermined time threshold, if the refrigerant concentration Cr at that time is less than the second predetermined concentration threshold, the refrigerant in the room 61 will soon be discharged to the outside 64, and the control unit 42 maintains the heat exchanger exhaust air passage 5 as the exhaust air passage.

[0087] When the determination in S26 is made, heat exchanger exhaust duct 5 was used as the exhaust air passage in the normal air supply / exhaust mode before switching to the emergency air supply / exhaust mode. Therefore, in this case, it is determined that the refrigerant that leaked into the room 61 has been successfully discharged to the outside 64, and when the mode returns from the emergency air supply / exhaust mode to the normal air supply / exhaust mode, it is highly likely that exhaust will be performed through heat exchanger exhaust duct 5. In the determination in S26, even if the elapsed time tr since the leakage has passed or is equal to or greater than the predetermined time threshold, if the refrigerant concentration Cr at that time is less than the second predetermined concentration threshold, the exhaust air passage can be maintained in heat exchanger exhaust duct 5, thereby making it possible to avoid switching the exhaust air passage when the mode returns to the normal air supply / exhaust mode.

[0088] (Disclosure Summary) A ventilation system 1 according to one embodiment of the present disclosure ventilates an indoor room 61 that is air-conditioned by an air conditioner 2, and includes a heat exchanger-type ventilation device 3 including an intake air duct 4, a heat exchanger 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 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 heat exchanger exhaust air duct 5 connects the indoor room 61 to the outdoor room 64 via the heat exchange element 38. The bypass exhaust air duct 6 connects the indoor room 61 to the outdoor room 64 without passing through the heat exchange element 38. The supply air fan 39 guides the supply air into the room 61 via the supply air duct 4. The exhaust fan 40 guides the exhaust air to the outside 64 via the heat exchanger exhaust air duct 5 or the bypass exhaust air duct 6. The exhaust air duct switching unit 41 switches between the heat exchanger exhaust air duct 5 and the bypass exhaust air duct 6 based on the temperature Ti of the room 61 and the temperature To of the outside 64. The acquisition unit 43 acquires detection information from the refrigerant sensor 24 that detects refrigerant leakage from the air conditioner 2. When the control unit 42 determines, 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 a predetermined concentration threshold, the control unit 42 stops controlling the switching by the exhaust air duct switching unit 41.

[0089] According to this aspect of the ventilation system 1, in the normal air supply / exhaust mode, ventilation is performed by switching between the heat exchanger exhaust air duct 5 and the bypass exhaust air duct 6 using the exhaust air duct switching unit 41 based on the temperature Ti of the room 61 and the temperature To of the outdoor room 64. On the other hand, if 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 exhaust air duct switching unit 41 stops switching. That is, if it is determined that there is a refrigerant leak from the air conditioner 2, exhaust air continues through the current air duct, whether it is the heat exchanger exhaust air duct 5 or the bypass exhaust air duct 6. In other words, if it is determined that there is a refrigerant leak from the air conditioner 2, the exhaust air duct switching unit 41 does not switch the exhaust air duct, and the exhaust fan 40 is not stopped in response to the switching. This allows the ventilation system 1 to quickly initiate the discharge of refrigerant leaking from the air conditioner 2 into the room 61, thereby effectively discharging the refrigerant to the outdoor room 64 in a short time.

[0090] When the control unit 42 determines, 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 a predetermined concentration threshold, the control unit 42 may maximize the airflow of the exhaust fan 40. This maximum airflow of the exhaust fan 40 is the maximum airflow set for the exhaust fan 40, and may be equal to or greater than the airflow that can be set for the exhaust fan 40 in a normal air supply / exhaust mode in which no refrigerant leakage from the air conditioner 2 has been detected. Furthermore, this maximum airflow of the exhaust fan 40 may be the maximum airflow that the exhaust fan 40 is capable of (i.e., the maximum airflow that can be set for the exhaust fan 40).

[0091] As a result, when it is determined that there is a refrigerant leak from the air conditioner 2, the air in the room 61 is exhausted to the outside 64 at the maximum air volume, so that the ventilation system 1 has the effect of being able to exhaust the refrigerant to the outside 64 in a short time.

[0092] At this time, if the control unit 42 determines, 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 a predetermined concentration threshold, the control unit 42 may maximize the airflow rate of the air supply fan 39. This maximum airflow rate of the air supply fan 39 is the maximum airflow rate set for the air supply fan 39, and may be equal to or greater than the airflow rate that can be set for the air supply fan 39 in the normal air supply / exhaust mode in which no refrigerant leakage from the air conditioner 2 has been detected. Furthermore, this maximum airflow rate of the air supply fan 39 may be the maximum airflow rate that the air supply fan 39 is capable of (i.e., the maximum airflow rate that can be set for the air supply fan 39).

[0093] When it is determined that there is a refrigerant leak from the air conditioner 2, maximizing the airflow of the exhaust fan 40 and also maximizing the airflow of the intake fan 39 has the effect of preventing the pressure in the room 61 from becoming too negative and making it easier to exhaust the refrigerant to the outside 64. In addition, because fresh air (outside air) from the outside 64 can be actively taken in, the ventilation system 1 has the effect of diluting the concentration Cr of the refrigerant in the room 61.

[0094] The ventilation system 1 may further include a timer unit 44 that measures the time elapsed since leakage tr, which is the time that has elapsed since the refrigerant concentration Cr detected by the refrigerant sensor 24 became equal to or greater than a predetermined concentration threshold. When the time elapsed since leakage tr measured by the timer unit 44 is equal to or greater than the predetermined time threshold and the exhaust fan 40 is exhausting through the heat exchanger exhaust air duct 5, the control unit 42 may control the exhaust air duct switching unit 41 to switch from the heat exchanger exhaust air duct 5 to the bypass exhaust air duct 6.

[0095] As a result, when it is determined that there is a refrigerant leak from the air conditioner 2 and the refrigerant is initially discharged to the outdoors 64 through the heat exchanger exhaust air duct 5, once a certain amount of refrigerant has been discharged through the heat exchanger exhaust air duct 5, the ventilation system 1 can switch the discharge of the refrigerant to the outdoors 64 to the bypass exhaust air duct 6, which is relatively easy to discharge. Therefore, even if an amount of refrigerant that cannot be discharged through the heat exchanger exhaust air duct 5 has leaked into the room 61, the ventilation system 1 has the advantage of being able to reliably discharge the refrigerant to the outdoors 64 by switching to the bypass exhaust air duct 6 midway.

[0096] 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 embodiment, including the modifications described in the above embodiments, may be modified by adding or replacing a part or parts of the configuration of another embodiment with that embodiment. Furthermore, the numerical values ​​given in each embodiment are merely examples, and other numerical values ​​may of course be adopted. [Industrial Applicability]

[0097] 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]

[0098] 1. Ventilation system 2. Air conditioners 3. Heat exchange ventilation system 4 Air supply duct 5 Heat exchanger 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 Heat exchanger exhaust air duct inside the device 37 Bypass exhaust air duct inside the device 38 Heat exchange element 39 Intake fan 40 Exhaust fan 41 Exhaust air path switching section 42 Control Unit 43 Acquisition Department 44 Timer section 45 Outdoor temperature sensor 46 Indoor temperature sensor 47 Return air filter 48 Outdoor air filter 51 Outdoor air intake 52 Indoor air outlet 53 Outdoor air duct 54 Air supply duct 55 Indoor air intake 56 Outdoor air outlet 57 Return air duct 58 Exhaust duct 62 Attic 63 Ceiling 64 Outdoors 65 Ventilation remote controller 66 Garari 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; a heat exchange exhaust air duct that communicates the indoor space with the outdoor space via the heat exchange element; a bypass exhaust air passage that communicates the indoor space with the outdoor space without passing through 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 heat exchanger exhaust air duct or the bypass exhaust air duct; an exhaust air passage switching unit that switches between the heat exchanger exhaust air passage and the bypass exhaust air passage based on the indoor temperature and the outdoor temperature; 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 ventilation system that stops switching control by the exhaust air path switching unit when it determines, 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 higher than a predetermined concentration threshold.

2. The control unit 2. The ventilation system according to claim 1, wherein the airflow rate of the exhaust fan is maximized 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.

3. The control unit 3. The ventilation system according to claim 1, wherein 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 airflow rate of the supply air fan is maximized.

4. The device further includes a timer that measures the time that has elapsed since the refrigerant concentration detected by the refrigerant sensor became equal to or greater than a predetermined concentration threshold, The control unit 2. The ventilation system of claim 1, wherein when the elapsed time since the leakage measured by the timer unit is equal to or greater than a predetermined time threshold and the exhaust fan is exhausting through the heat exchanger exhaust air duct, the exhaust air duct switching unit is controlled to switch from the heat exchanger exhaust air duct to the bypass exhaust air duct.

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