Patent Publication Number: US-2022214062-A1

Title: Air conditioning and ventilating system

Description:
TECHNICAL FIELD 
     The present disclosure relates to air conditioning and ventilating systems. In more detail, the present disclosure relates to an air conditioning and ventilating system including an air conditioning device and a ventilation device. 
     BACKGROUND ART 
     In relatively large buildings such as office buildings and hotels, an air conditioning device that generates cold air and hot air, and a ventilation device that supplies outside air into the room and exhausts air from the room are usually used together. 
     If a refrigerant leaks from the air conditioning device into the room, an oxygen deficiency or other inconveniences may occur. To prevent an occurrence of such an inconvenience, it has conventionally been proposed to activate the ventilation device when refrigerant leakage is detected (see, for example, Patent Literature 1). 
     In the air conditioning and ventilating system described in Patent Literature 1, when refrigerant leakage is detected while an air conditioning device is connected to a ventilation device to communicate with each other, a control device of the air conditioning device instructs a control device of the ventilation device to operate the ventilation device. Then, if a trouble of the ventilation device or the like causes a shortage of airflow volume of the ventilation device, the control device of the air conditioning device increases the airflow volume of the air conditioning device. This inhibits the leaked refrigerant from accumulating in air conditioned space and causing insufficient discharge of the refrigerant. 
     CITATION LIST 
     Patent Literature 
     PATENT LITERATURE 1: Japanese Unexamined Patent Publication No. 2016-223643 
     SUMMARY 
     An air conditioning and ventilating system according to the present disclosure includes: 
     an air conditioning device including a heat exchanger configured to generate conditioned air by heat exchange with a refrigerant; 
     a ventilation device communicatively connected to the air conditioning device and including a supply air fan and/or an exhaust fan; 
     an airflow volume detection unit configured to detect an airflow volume equivalent value of the ventilation device; and 
     a control unit, 
     in which on determination that the airflow volume equivalent value acquired from the airflow volume detection unit is equal to or less than a first predetermined value, the control unit sets an operation of the air conditioning device to a stop state. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an explanatory diagram of a refrigerant pipe system and an air system of one embodiment of an air conditioning and ventilating system of the present disclosure. 
         FIG. 2  is a block diagram showing configurations of a central controller and control units of an outdoor unit, an indoor unit, a ventilation device, and a remote control device. 
         FIG. 3  is a perspective explanatory diagram showing a configuration of a total heat exchanger in the ventilation device. 
         FIG. 4  is a flowchart showing one example of activation of the ventilation device. 
         FIG. 5  is a flowchart showing another example of activation of the ventilation device. 
         FIG. 6  is an explanatory diagram of a refrigerant pipe system and an air system of a modification of the air conditioning and ventilating system shown in  FIG. 1 . 
         FIG. 7  is a block diagram showing configurations of the central controller, and control units of the outdoor unit, the indoor unit, the ventilation device, the remote control device, and an auxiliary fan in the air conditioning and ventilating system shown in  FIG. 6 . 
     
    
    
     DETAILED DESCRIPTION 
     An air conditioning and ventilating system according to the present disclosure will be described in detail below with reference to the accompanying drawings. Note that the present disclosure is not limited to the following exemplification, but is intended to include all changes within meanings and a scope of claims and equivalents. 
     [Overall Configuration of Air Conditioning and Ventilating System] 
       FIG. 1  is an explanatory diagram showing a refrigerant pipe system and an air system of an air conditioning and ventilating system S according to one embodiment of the present disclosure. The air conditioning and ventilating system S includes a refrigerant pipe method distributed air conditioning device. The air conditioning and ventilating system S cools and heats a room R by executing a vapor compression refrigeration cycle operation, and ventilates the room R by the ventilation device to be described later. 
     The type of room R, which is air conditioned space to which the air conditioning and ventilating system S is applied, is not particularly limited in the present disclosure, and includes all spaces or areas that are cooled and/or heated and ventilated, such as offices, hotels, theaters, and stores. The air conditioning and ventilating system S includes an outdoor (heat source) unit  10  installed outside the room R, indoor units  20 , which are air conditioning devices installed inside the room R, a ventilation device  30 , and a central controller  40 . The outdoor unit  10  and the indoor units  20  constitute an air conditioning device A. The outdoor unit  10  and the indoor units  20  are connected by a liquid refrigerant connection pipe  11  and a gas refrigerant connection pipe  12 . In addition, the ventilation device  30  and the room R are connected by a supply air (SA) duct  31  and a return air (RA) duct  32 . In the room R, the indoor units  20  may be installed on a floor, near a ceiling, or in ceiling space. Note that  FIG. 1  depicts only two indoor units  20 , but the number of indoor units  20  may be one, or three or more. In addition, in the embodiment shown in  FIG. 1 , one outdoor unit  10  is connected to the indoor units  20  of the room R, which is one air conditioned space, but one outdoor unit  10  may be connected to a plurality of indoor units disposed in a plurality of rooms R. In this case, the ventilation device is disposed in each room. 
     The central controller  40  includes a CPU  401 , a storage unit  402 , and a transmission and reception unit  403 , as shown in  FIG. 2 . The central controller  40  communicates with control units of the outdoor unit  10 , the indoor units  20 , and the ventilation device  30  to be described later via the transmission and reception unit  403  to control the operation of each device. 
     The outdoor unit  10  and the indoor units  20  can execute air conditioning of the room R by executing a well-known refrigeration cycle operation. Note that detailed description of a well-known refrigerant circuit inside each of the outdoor unit  10  and the indoor units  20  will be omitted, and only parts related to the present disclosure will be described below. 
     The outdoor unit  10  includes a compressor  13 , a four-way switching valve  14 , an outdoor heat exchanger  15 , an outdoor expansion valve  16 , a liquid shutoff valve  17 , a gas shutoff valve  18 , an outdoor fan  19 , and a control unit  41 . In the air conditioning and ventilating system S according to the present embodiment, the outdoor unit  10 , the two indoor units  20 , and the ventilation device  30  are communicably connected to each other. 
     The compressor  13  is a hermetic type compressor driven by a motor for the compressor (not shown), and takes in a gas refrigerant from an intake flow path  13   a  on an intake side of the compressor  13 . 
     The four-way switching valve  14  is a mechanism for switching a refrigerant flow direction. As indicated by solid lines in  FIG. 1 , during a cooling operation, the four-way switching valve  14  connects a refrigerant pipe  13   b  on a discharge side of the compressor  13  to one end of the outdoor heat exchanger  15 , and connects the intake flow path  13   a  on the intake side of the compressor  13  to the gas shutoff valve  18 . With this configuration, the outdoor heat exchanger  15  functions as a condenser for the refrigerant compressed by the compressor  13 , and an indoor heat exchanger to be described later functions as an evaporator for the refrigerant condensed by the outdoor heat exchanger  15 . 
     In addition, as indicated by broken lines in  FIG. 1 , during a heating operation, the four-way switching valve  14  connects the refrigerant pipe  13   b  on the discharge side of the compressor  13  to the gas shutoff valve  18 , and connects the intake flow path  13   a  to one end of the outdoor heat exchanger  15 . With this configuration, the indoor heat exchanger functions as a condenser for the refrigerant compressed by the compressor  13 , and the outdoor heat exchanger  15  functions as an evaporator for the refrigerant cooled by the indoor heat exchanger. 
     The outdoor fan  19  takes in outside air into the outdoor unit  10  and discharges, to the outdoors, outside air that has undergone heat exchange with the refrigerant flowing through the outdoor heat exchanger  15 . 
     The control unit  41  includes a CPU  411 , a storage unit  412 , and a transmission and reception unit  413 , as shown in  FIG. 2 . The control unit  41  is communicatively connected to the central controller  40  via the transmission and reception unit  413  to control the operation of the compressor  13  and the like. 
     The indoor units  20  are each connected to the outdoor unit  10  via the refrigerant connection pipes  11  and  12 . The two indoor units  20  shown in  FIG. 1  both have the same external and internal structure. Each indoor unit  20  includes an indoor expansion valve  21 , an indoor heat exchanger  22 , an indoor fan  23 , a refrigerant sensor  24 , and a control unit  25 . 
     The indoor fan  23  takes in air of the room R into the indoor unit  20  and supplies conditioned air that has undergone heat exchange with the refrigerant flowing through the indoor heat exchanger  22  to the room R. 
     The refrigerant sensor  24  detects concentration of the refrigerant leaking from the refrigerant pipe or the like. The refrigerant sensor  24  continuously or intermittently outputs an electrical signal according to detected values to the control unit  25 . This electrical signal varies in voltage according to the refrigerant concentration detected by the refrigerant sensor  24 . 
     The location of the refrigerant sensor  24  is not particularly limited if the leaked refrigerant can be detected. The refrigerant sensor  24  is preferably disposed, for example, near a place where the refrigerant is likely to leak, such as a joint point between the refrigerant pipes, a place where the refrigerant pipe is curved at 90 degrees or more, and a place where the pipe is thin. Note that in addition to being disposed inside the indoor unit  20 , the refrigerant sensor  24  can also be mounted, for example, in the remote controller described later to set the room temperature, airflow volume, or the like, or can be disposed on a wall surface or other suitable place in the room. 
     The control unit  25  includes a CPU  251 , a storage unit  252 , and a transmission and reception unit  253 , as shown in  FIG. 2 . The control unit  25  is communicatively connected to the central controller  40  via the transmission and reception unit  253 . The control unit  25  controls the operation of the indoor fan  23  and the like in the indoor unit  20 . The control unit  25  receives an electrical signal from the refrigerant sensor  24  via the transmission and reception unit  253 . 
     The ventilation device  30  exchanges heat with fresh outside air OA and supplies the air to the room R as supply air SA, and discharges the return air RA from the room R to the outside of the device. The ventilation device  30  includes a total heat exchanger  33 , a supply air fan  34 , an exhaust fan  35 , a control unit  36 , a supply airflow volume detection unit  37 , and an exhaust airflow volume detection unit  38 . 
     The total heat exchanger  33  in the present embodiment is an orthogonal total heat exchanger configured such that the outside air OA from outside the room and the return air RA from inside the room are almost orthogonal. The total heat exchanger  33  is, as shown in  FIG. 3 , a laminated body of a thermally conductive and moisture-permeable flat plate-shaped partition plate  33   a,  and a corrugated spacing plate  33   b  laminated in turn in the up-and-down direction in  FIG. 3 . The spacing plate  33   b  has a cross section that looks like nearly triangular cross sections arranged side by side when viewed from the ventilation direction (direction indicated by the hollow arrow or black arrow in  FIG. 3 ), and keeps the flow path height by the height of the triangle. The spacing plate  33   b  is laminated at an angle of 90 degrees different at each sheet such that a corrugated cross section appears on every other sheet in the up-and-down direction (up-and-down direction in  FIG. 3 ) on a certain side with the partition plate  33   a  interposed therebetween. With this configuration, a supply air side passage (see the hollow arrow in  FIG. 3 ) and an exhaust side passage (see black arrow in  FIG. 3 ) are formed with the thermally conductive and moisture-permeable partition plate  33   a  interposed therebetween. Sensible heat and latent heat are exchanged via the partition plate  33   a.  The ventilation device  30  in the present embodiment is a class 1 ventilation device in which air is supplied by a fan and exhausted by a fan. Note that as the ventilation device in the present disclosure, a class 2 ventilation device may be used, in which air is supplied by a fan and exhausted naturally, or a class 3 ventilation device may be used, in which air is exhausted by a fan and supplied naturally. 
     The control unit  36  includes a CPU  361 , a storage unit  362 , and a transmission and reception unit  363 , as shown in  FIG. 2 . The control unit  36  is communicatively connected to the central controller  40 , the supply airflow volume detection unit  37 , and the exhaust airflow volume detection unit  38  via the transmission and reception unit  363 . The supply airflow volume detection unit  37  detects an airflow volume equivalent value of the supply air fan  34 . The exhaust airflow volume detection unit  38  detects an airflow volume equivalent value of the exhaust fan  35 . The supply airflow volume detection unit  37  and the exhaust airflow volume detection unit  38  may be airflow volume sensors that detect the airflow volume of the supply air fan  34  and the exhaust fan  35 . If the airflow volume sensor is used, the airflow volume equivalent value may be, for example, a voltage value corresponding to the airflow volume. 
     In the ventilation device  30  in the present embodiment, the control unit  36  executes fixed airflow volume control that adjusts the number of revolutions of each of the supply air fan  34  and the exhaust fan  35  to cause a supply airflow volume and exhaust airflow volume to approach respective target values. The storage unit  362  stores a target supply airflow volume, which is a target value for the supply airflow volume, and a target exhaust airflow volume, which is a target value for the exhaust airflow volume. When the airflow volume sensors are used as the supply airflow volume detection unit  37  and the exhaust airflow volume detection unit  38 , the target supply airflow volume and the target exhaust airflow volume stored in the storage unit  362  are voltage values according to respective airflow volumes. The control unit  36  executes the fixed airflow volume control by referring to the target supply airflow volume and the target exhaust airflow volume stored in the storage unit  362  based on a supply airflow volume equivalent value and an exhaust airflow volume equivalent value detected by the supply airflow volume detection unit  37  and the exhaust airflow volume detection unit  38 , respectively. In addition, the storage unit  362  stores the number of revolutions of the supply air fan  34  and the exhaust fan  35  at the start of operation of the ventilation device  30 . The number of revolutions at the initial start of operation may be the number of revolutions determined at the time of trial operation, or may be the preset number of revolutions. The number of revolutions at the second and subsequent start of operation may be the preset number of revolutions, or the final number of revolutions at the previous operation may be stored. 
     In the present embodiment, a remote controller  50  is disposed in the room R. The remote controller  50  includes a display unit  51 , a control unit  52 , and an input unit  53 . The display unit  51  displays information such as the operating mode of the indoor unit  20  and the room temperature, and also functions as an alarm unit for issuing (displaying) alarms and advance alarms as described below. The control unit  52  includes a CPU  521 , a storage unit  522 , and a transmission and reception unit  523 , as shown in  FIG. 2 . The control unit  52  is communicatively connected to the control units  25  of the two indoor units  20 , the control unit  36  of the ventilation device  30 , and the central controller  40  via the transmission and reception unit  523  to control the operation of the remote controller  50 . By manipulating the input unit  53 , the user can adjust the temperature, start and stop the device operation, and the like. 
     The central controller  40  and the control units  25 ,  36 ,  41 , and  52  each include a computer (CPU), and implement necessary control functions by the computer executing software (computer program). The software is stored in the storage unit of each of the central controller  40  and the control units  25 ,  36 ,  41 , and  52 . The central controller  40  and the control units  25 ,  36 ,  41 , and  52  are connected to each other by communication lines, making it possible to coordinate control and share information. 
     [Basic Operation of Air Conditioning Device A] 
     The air conditioning device A having the above-described configuration executes the cooling operation or heating operation as follows. 
     During the cooling operation, as described above, the four-way switching valve  14  is in the state shown by the solid lines in  FIG. 1 . In this state, the high-pressure gas refrigerant discharged from the compressor  13  is sent to the outdoor heat exchanger  15  that functions as a condenser via the four-way switching valve  14 , and is cooled by exchanging heat with the outside air supplied by the outdoor fan  19 . The high-pressure refrigerant cooled and liquefied in the outdoor heat exchanger  15  is sent to each indoor unit  20  via the liquid-refrigerant connection pipe  11 . The refrigerant sent to each indoor unit  20  is decompressed by the indoor expansion valve  21  to become a low-pressure gas-liquid two-phase state refrigerant, exchanges heat with the air of the room R in the indoor heat exchanger  22  that functions as an evaporator, and evaporates to become a low-pressure gas refrigerant. The low-pressure gas refrigerant heated in the indoor heat exchanger  22  is sent to the outdoor unit  10  via the gas-refrigerant connection pipe  12 , and is taken in again into the compressor  13  via the four-way switching valve  14 . 
     On the other hand, during the heating operation, as described above, the four-way switching valve  14  is in the state shown by the broken lines in  FIG. 1 . In this state, the high-pressure gas refrigerant discharged from the compressor  13  is sent to each indoor unit  20  via the four-way switching valve  14  and the gas-refrigerant connection pipe  12 . The high-pressure gas refrigerant sent to each indoor unit  20  is sent to the indoor heat exchanger  22  that functions as a condenser, cooled by exchanging heat with the air of the room R, passes through the indoor expansion valve  21 , and is sent to the outdoor unit  10  via the liquid-refrigerant connection pipe  11 . The high-pressure refrigerant sent to the outdoor unit  10  is decompressed by the outdoor expansion valve  16  to become the low-pressure gas-liquid two-phase state refrigerant, and flows into the outdoor heat exchanger  15  that functions as an evaporator. The low-pressure gas-liquid two-phase state refrigerant that has flowed into the outdoor heat exchanger  15  is heated by exchanging heat with the outside air supplied by the outdoor fan  19 , and evaporates to become a low-pressure refrigerant. The low-pressure gas refrigerant leaving the outdoor heat exchanger  15  is taken in again into the compressor  13  via the four-way switching valve  14 . 
     [Basic Operation of Ventilation Device  30 ] 
     The ventilation device  30  is linked to the operation of the air conditioning device A. When the operation of the air conditioning device A is started, the operation of the ventilation device  30  is also started, and when the operation of the air conditioning device A is stopped, the operation of the ventilation device  30  is also stopped. 
     The control unit  36  executes the above-described fixed airflow volume control. Specifically, as shown in  FIG. 4 , the following control is executed. 
     In step S 1 , the CPU  361  of the control unit  36  of the ventilation device  30  starts the operation of the ventilation device  30  in conjunction with the operation of the air conditioning device A. 
     In step S 2 , the CPU  361  controls the number of revolutions of each of the supply air fan  34  and the exhaust fan  35  in order to reach the predetermined rotation stored in the storage unit  362 . 
     In step S 3 , the supply airflow volume detection unit  37  acquires the airflow volume equivalent value of the supply airflow volume and transmits the acquired airflow volume equivalent value to the control unit  36 . 
     In step S 4 , the CPU  361  of the control unit  36  compares the acquired airflow volume equivalent value of the supply airflow volume with the target supply airflow volume stored in the storage unit  362 , and determines whether the airflow volume equivalent value is within a predetermined range from the target supply airflow volume. On determination that the airflow volume equivalent value is within the predetermined range from the target supply airflow volume, the CPU  361  returns to step S 3 . 
     On the other hand, in step S 4 , on determination that the airflow volume equivalent value is not within the predetermined range from the target supply airflow volume, the CPU  361  of the control unit  36  proceeds to step S 5 . 
     In step S 5 , when the airflow volume equivalent value is lower than the target supply airflow volume beyond the predetermined range, the CPU  361  of the control unit  36  increases the number of revolutions of the supply air fan  34  over the current number of revolutions based on the current airflow volume equivalent value. In addition, when the airflow volume equivalent value is higher than the target supply airflow volume beyond the predetermined range, the CPU  361  decreases the number of revolutions of the supply air fan  34  over the current number of revolutions based on the current airflow volume equivalent value. 
     In step S 6  parallel with step S 3 , the exhaust airflow volume detection unit  38  acquires the airflow volume equivalent value of the exhaust airflow volume and transmits the acquired airflow volume equivalent value to the control unit  36 . 
     In step S 7 , the CPU  361  of the control unit  36  compares the acquired airflow volume equivalent value of the exhaust airflow volume with the target exhaust airflow volume stored in the storage unit  362 , and determines whether the airflow volume equivalent value is within a predetermined range from the target exhaust airflow volume. On determination that the airflow volume equivalent value is within the predetermined range from the target exhaust airflow volume, the CPU  361  returns to step S 6 . 
     On the other hand, in step S 7 , on determination that the airflow volume equivalent value is not within the predetermined range from the target exhaust airflow volume, the CPU  361  of the control unit  36  proceeds to step S 8 . 
     In step S 8 , when the airflow volume equivalent value is lower than the target exhaust airflow volume beyond the predetermined range, the CPU  361  of the control unit  36  increases the number of revolutions of the exhaust fan  35  over the current number of revolutions based on the current airflow volume equivalent value. In addition, when the airflow volume equivalent value is higher than the target exhaust airflow volume beyond the predetermined range, the CPU  361  decreases the number of revolutions of the exhaust fan  35  over the current number of revolutions based on the current airflow volume equivalent value. 
     As described above, the ventilation device  30  is linked to the air conditioning device A. When the operation of the air conditioning device A is stopped, the operation of the ventilation device  30  is also stopped. On receipt of information that the operation of the air conditioning device A is stopped, directly from the control unit  25  of the indoor unit  20 , or indirectly via the central controller  40 , the CPU  361  of the control unit  36  stops the operation of the ventilation device  30  even during the processing of any of the steps shown in  FIG. 4 . 
     [Operation when Airflow Volume of Ventilation Device  30  Decreases] 
     Next, the operation of the air conditioning and ventilating system S when the airflow volume of the ventilation device  30  decreases will be described. 
     As described above, when the supply air volume and the exhaust air volume decrease during the fixed airflow volume control, the ventilation device  30  increases the supply air volume and the exhaust air volume by increasing the number of revolutions of the supply air fan  34  and the exhaust fan  35 . However, an upper limit is set for the number of revolutions of each of the supply air fan  34  and the exhaust fan  35  of the ventilation device  30 , and after the number of revolutions reaches the upper limit, the airflow volume cannot be increased any more. Therefore, the air conditioning and ventilating system S according to the present embodiment executes the following control when the number of revolutions of the supply air fan  34  and the exhaust fan  35  reaches the upper limit and the supply airflow volume and the exhaust airflow volume decrease equal to or less than the predetermined lower limit value. 
     In the flowchart shown in  FIG. 5 , step S 101  to step S 104  show the same process as in step S 1  to step S 4  in the flowchart shown in  FIG. 4 , respectively. In addition, step S 108  and step S 109  in  FIG. 5  also show the same process as in step S 6  and step S 7  in  FIG. 4 , respectively. Therefore, for simplicity, descriptions of the same process are omitted. 
     In step S 104 , on determination that the airflow volume equivalent value is not within the predetermined range from the target supply airflow volume, in step S 105 , the CPU  361  of the control unit  36  determines whether the airflow volume equivalent value is equal to or less than the lower limit supply airflow volume. In step S 105 , on determination that the airflow volume equivalent value is higher than the lower limit supply airflow volume, the CPU  361  proceeds to step S 106 . In step S 106 , as in step S 5  of  FIG. 4 , the CPU  361  increases or decreases the number of revolutions of the supply air fan  34  over the current number of revolutions based on the current airflow volume equivalent value, and then returns to step S 103 . 
     On the other hand, in step S 105 , on determination that the airflow volume equivalent value is equal to or less than the lower limit supply airflow volume, the CPU  361  of the control unit  36  proceeds to step S 107  and sends a signal to the central controller  40  in step S 107 . 
     In step S 109 , on determination that the airflow volume equivalent value is not within the predetermined range from the target exhaust airflow volume, in step S 110 , the CPU  361  of the control unit  36  determines whether the airflow volume equivalent value is equal to or less than the lower limit exhaust airflow volume. In step S 110 , on determination that the airflow volume equivalent value is higher than the lower limit exhaust airflow volume, the CPU  361  proceeds to step S 111 . In step S 111 , as in step S 5  of  FIG. 4 , the CPU  361  increases or decreases the number of revolutions of the exhaust fan  35  over the current number of revolutions based on the current airflow volume equivalent value, and then returns to step S 108 . 
     On the other hand, in step S 110 , on determination that the airflow volume equivalent value is equal to or less than the lower limit exhaust airflow volume, the CPU  361  of the control unit  36  proceeds to step S 112  and sends a signal to the central controller  40  in step S 112 . 
     Step S 108  to step S 112  are performed in parallel with step S 103  to step S 107 . 
     In step S 113 , on receipt of the signal from the control unit  36  that at least one of the supply airflow volume and the exhaust airflow volume has become equal to or less than the lower limit, the CPU  401  of the central controller  40  instructs the control unit  41  of the outdoor unit  10  to stop the operation of the compressor  13 . 
     In step S 114 , on receipt of the instruction from the central controller  40 , the CPU  411  of the control unit  41  of the outdoor unit  10  stops the operation of the compressor  13 . 
     In step S 115 , the CPU  401  of the central controller  40  instructs the control unit  52  of the remote controller  50  to display a warning on the display unit  51  of the remote controller  50 . 
     In step S 116 , on receipt of the instruction from the central controller  40 , the CPU  521  of the control unit  52  causes the display unit  51  to display the warning. 
     This warning or alarm is performed by causing the display unit  51  to display a statement indicating that the ventilation airflow volume of the ventilation device  30  is decreasing or flashing a phrase such as “airflow volume of ventilation device has decreased” or a symbol indicating content thereof. By issuing an alarm by the display unit  51 , a service technician or user can easily understand that the ventilation device  30  has a fault and does not secure normal ventilation airflow volume. This makes it possible to urge the service technician or user to solve the fault of the ventilation device  30 . Then, solving the fault of the ventilation device  30  makes it possible to inhibit the shortage of the ventilation airflow volume if the refrigerant leaks. 
     The air conditioning and ventilating system S according to the present embodiment is, as described above, a class 1 ventilation device, which supplies air with the supply air fan and exhausts air with the exhaust fan. The “ventilation airflow volume” is a supply airflow volume or an exhaust airflow volume. In contrast, for a class 2 ventilation device, which supplies air with a fan and exhausts air naturally, the “ventilation airflow volume” refers to a supply airflow volume, or for a class 3 ventilation device, which exhausts air with a fan and supplies air naturally, the “ventilation airflow volume” refers to an exhaust airflow volume. 
     [Method for Calculating Lower Limit Supply Airflow Volume and Lower Limit Exhaust Airflow Volume (First Predetermined Value)] 
     The above-described “lower limit supply airflow volume” and “lower limit exhaust airflow volume” can be selected based on various guidelines that specify safety measures for a leaked refrigerant, and the like. For example, the IEC standard or GL-16 (JRA) defines the ventilation amount required to take safety measures against refrigerant leakage by ventilation. Note that the “lower limit supply airflow volume” and the “lower limit exhaust airflow volume” may have the same or different settings. Hereinafter, the “lower limit supply airflow volume” and the “lower limit exhaust airflow volume” are assumed to have the same settings and are referred to as the “first predetermined value.” 
     The present embodiment sets the “first predetermined value” based on JRA GL-16:2017, which is a guideline set by the Japan Refrigeration and Air Conditioning Industry Association (JRAIA). The guideline stipulates that the ventilation device has ventilation capacity equal to or greater than the number of ventilations calculated by Formula (1) below as a safety measure against the leaked refrigerant. 
         n≥ 50/( G×V )  (1)
 
     Here, n is the number of ventilations (times/h), and G and V are LFL (kg/m 3 ) and room volume (m 3 ), respectively. LFL is the lower flammability limit, and is the minimum concentration of refrigerant that allows a flame to spread with the refrigerant and air uniformly mixed, as defined in ISO 817. For example, for the R32 refrigerant, LFL is 0.307 kg/m 3 . 
     When the area and height of the room are 100 m 3  and 3 m respectively, the volume V of the room is 300 m 3 . When R32 is used as a refrigerant, LFL of R32 is 0.307 kg/m 3 , and thus the required number of ventilations n is equal to or greater than 50/(0.307×300)=0.543 times/h from Formula (1). Therefore, the required ventilation capacity of this room (ventilation airflow volume) is 0.543 time/h×300 m 3 /time=163 m 3 /h or more. 
     The “first predetermined value” can be, for example, a value equal to or greater than the required ventilation capacity (ventilation airflow volume) calculated by Formula (1) above. When the value calculated in the above calculation example is the first predetermined value, the first predetermined value is 163 m 3 /h. Therefore, when the control unit  36  determines that at least one of the supply airflow volume of the ventilation device  30  detected by the supply airflow volume detection unit  37  and the exhaust airflow volume of the ventilation device  30  detected by the exhaust airflow volume detection unit  38  is equal to or less than 163 m 3 /h, the operation of the compressor  13  of the outdoor unit  10  is set to the stop state. That is, the operation of the compressor  13  in an operating state is stopped. In addition, the stop state of the compressor  13  that is not in an operating state is maintained. 
     MODIFICATION 1 
     In the air conditioning and ventilating system S in modification 1, an auxiliary fan  60  may be provided separately from the ventilation device  30  to assist supply air and exhaust by the ventilation device  30 .  FIG. 6  is an explanatory diagram of a refrigerant pipe system and an air system of the modification of the air conditioning and ventilating system S shown in  FIG. 1  with the auxiliary fan  60  provided. In addition,  FIG. 7  is a block diagram showing configurations of the central controller, and control units of the outdoor unit, the indoor unit, the ventilation device, the remote control device, and the auxiliary fan in the air conditioning and ventilating system shown in  FIG. 6 . In  FIGS. 6 and 7 , elements or configurations that are common to the elements or configurations shown in  FIGS. 1 and 2  have the same reference symbols as in  FIGS. 1 and 2 , respectively, and the description thereof will be omitted for the sake of simplicity. 
     The auxiliary fan  60  is a ventilation fan disposed separately from the ventilation device  30 . The auxiliary fan  60  includes an auxiliary supply air fan  61 , an auxiliary exhaust fan  62 , and a control unit  67 . The auxiliary fan  60  and the room R are connected to each other by a blast duct  63  and a blast duct  64 . The blast duct  63  is connected to a supply air duct  31  that connects the ventilation device  30  to the room R. The blast duct  64  is connected to a return air duct  32  that connects the ventilation device  30  to the room R. Inside the blast duct  63 , an electric damper  65  that opens and closes the blast duct  63  is disposed. Inside the blast duct  64 , an electric damper  66  that opens and closes the blast duct  64  is disposed. The control unit  67  controls the operation of the auxiliary supply air fan  61 , the auxiliary exhaust fan  62 , the electric damper  65 , and the electric damper  66 . The control unit  67  includes a CPU  671 , a storage unit  672 , and a transmission and reception unit  673 , as shown in  FIG. 7 . The control unit  67  is communicatively connected to the central controller  40  via the transmission and reception unit  673 . Note that the blast ducts  63  and  64  can also be connected directly to the room R without joining the supply air duct  31  and the return air duct  32  of the ventilation device  30 , respectively. 
     [Operation of Auxiliary Fan  60  when Airflow Volume of Ventilation Device  30  Decreases] 
     In the present modification, when the determination in step S 105  and step S 110  in  FIG. 5  is No, for example, the following control can be executed. 
     On determination in step S 105  that the airflow volume equivalent value is higher than the lower limit supply airflow volume (determination in step S 105  is No), the CPU  361  of the control unit  36  determines whether the airflow volume equivalent value is equal to or less than a second predetermined value. The second predetermined value is a value greater than the lower limit supply airflow volume. On determination that the airflow volume equivalent value is equal to or less than the second predetermined value, the CPU 361  sends a signal to the central controller  40 . On the other hand, on determination that the airflow volume equivalent value is not equal to or less than the second predetermined value, the CPU 361  proceeds to step  5106 . 
     In addition, on determination in step S 110  that the airflow volume equivalent value is higher than the lower limit exhaust airflow volume (determination in step S 110  is No), the CPU  361  determines whether the airflow volume equivalent value is equal to or less than the second predetermined value. The second predetermined value is a value greater than the lower limit exhaust airflow volume. On determination that the airflow volume equivalent value is equal to or less than the second predetermined value, the CPU 361  sends a signal to the central controller  40 . On the other hand, on determination that the airflow volume equivalent value is not equal to or less than the second predetermined value, the CPU 361  proceeds to step S 111 . 
     On receipt of the signal from the control unit  36  indicating that at least one of the supply airflow volume and the exhaust airflow volume is within the above-described range, the CPU  401  of the central controller  40  instructs the control unit  67  of the auxiliary fan  60  to start the operation. The control unit  67  starts the operation of the auxiliary fan  60 . Specifically, since the auxiliary fan  60  includes the auxiliary supply air fan  61  and the auxiliary exhaust fan  62 , the control unit  67  activates both the auxiliary supply air fan  61  and the auxiliary exhaust fan  62 . Before the activation of the auxiliary supply air fan  61 , the electric damper  65 , which normally closes the blast duct  63 , is opened. The air from the auxiliary supply air fan  61  is supplied to the room R along with the supply air SA from the ventilation device  30 . In addition, before the activation of the auxiliary exhaust fan  62 , the electric damper  66 , which normally closes the blast duct  64 , is opened. The return air RA from the room R is split into the ventilation device  30  and the auxiliary fan  60 , and exhausted outside the room. 
     After the operation of the auxiliary fan  60  is started, the CPU  361  of the control unit  36  returns to steps S 106  and S 111 . In the subsequent processing, the supply airflow volume is the sum of the supply airflow volume of the ventilation device  30  and the supply airflow volume of the auxiliary supply air fan  61 . In addition, the exhaust airflow volume is the sum of the exhaust airflow volume of the ventilation device and the exhaust airflow volume of the auxiliary exhaust fan  62 . The airflow volume of each of the auxiliary supply air fan  61  and the auxiliary exhaust fan  62  can also be determined by the same mechanism as the airflow volume detection units  37  and  38  of the ventilation device  30 . When an auxiliary fan of fixed airflow volume is used to simplify the configuration, the fixed airflow volume may be set in advance. 
     After that, in step S 105 , on determination that the sum of the supply airflow volume of the ventilation device  30  and the supply airflow volume of the auxiliary supply air fan  61  is equal to or less than the lower limit supply airflow volume, the CPU  361  of the control unit  36  sends a signal to the central controller  40 . In addition, in step S 110 , on determination that the sum of the exhaust airflow volume of the ventilation device  30  and the exhaust airflow volume of the auxiliary exhaust fan  62  is equal to or less than the lower limit exhaust airflow volume, the CPU  361  sends a signal to the central controller  40 . On receipt of the signal indicating that at least one of the supply airflow volume and the exhaust airflow volume is equal to or less than the lower limit value, the CPU  401  of the central controller  40  sets the operation of the compressor  13  to the stop state and causes the display unit  51  to issue an alarm. 
     As described above, by activating the auxiliary fan  60 , it is possible to compensate for the reduced airflow volume of the ventilation device  30 . In addition, the CPU  401  may start the operation of the auxiliary fan  60  and cause the display unit  51  of the remote controller  50  to issue an advance alarm different from the above-described alarm. By issuing the advance alarm, before the forced stop of the indoor unit  20  in operation, the service technician or user can be notified of the fault of the ventilation device to take measures to solve the fault. The advance alarm can be issued, in the same manner as the above-described alarm, by displaying a statement indicating that the decrease in the airflow volume of the ventilation device  30  is approaching a danger zone, or flashing a phrase such as “caution: airflow volume of ventilation device has decreased” or a symbol indicating content thereof. 
     In addition, when the lower limit value of at least one of the supply airflow volume and the exhaust airflow volume cannot be secured even with the assistance of the airflow volume by the auxiliary fan  60 , the CPU  401  sets the operation of the compressor  13  to the stop state and causes the display unit  51  to issue an alarm. This makes it possible to notify the service technician or user that the normal ventilation airflow volume is not secured and to urge the solution of the fault of the ventilation device  30 . Therefore, it is possible to inhibit the shortage of the airflow volume of the ventilation device  30  if the refrigerant leaks. 
     Here, the “second predetermined value” is a value greater than the “lower limit supply airflow volume” and the “lower limit exhaust airflow volume” (“first predetermined value”), and can be, for example, a value of 105 to 110% of the required ventilation capacity calculated by Formula (1). Specifically, when 105% of the value calculated in the above calculation example is the second predetermined value, the second predetermined value is 163×1.05=171.15 m 3 /h. Therefore, when the control unit  36  determines that at least one of the supply airflow volume and the exhaust airflow volume is 171.15 m 3 /h or less, the operation of the auxiliary fan  60  is started. Note that the “second predetermined value” of the supply airflow volume and the exhaust airflow volume, which is the same value in the above description, may be different values. 
     MODIFICATION 2 
     In the air conditioning and ventilating system S in modification 2, in the control of  FIG. 5 , before at least one of the supply airflow volume and the exhaust airflow volume becomes equal to or less than the lower limit value and the operation of the air conditioning device A is set to the stop state, the “advance alarm” to notify the service technician or user that the ventilation airflow volume is decreasing may be issued. The timing for issuing the advance alarm may be the same as the timing for starting the operation of the auxiliary fan  60  in modification 1. That is, this may be the case where the CPU  361  of the control unit  36  determines that at least one of the supply airflow volume and the exhaust airflow volume of the ventilation device  30  is greater than the first predetermined value (lower limit supply airflow volume, lower limit exhaust airflow volume), and is equal to or less than the second predetermined value greater than the first predetermined value. The contents of the advance alarm are the same as in modification 1. 
     By issuing the advance alarm by the display unit  51 , the service technician or user can understand that the ventilation device  30  has a fault and does not secure normal ventilation airflow volume, and that the airflow volume decrease is approaching a danger zone. By notifying the service technician or user of the fault of the ventilation device  30  and urging the solution of the fault before the forced stop of the air conditioning device in operation, it is possible to avoid the inconvenience caused by the forced stop of the air conditioning device. 
     MODIFICATION 3 
     In the air conditioning and ventilating system S in modification 3, the supply airflow volume detection unit  37  and the exhaust airflow volume detection unit  38  may each be a sensor that measures power consumption of each motor (not shown) that activates the supply air fan  34  and the exhaust fan  35 . When the power consumption sensor is used, the airflow volume equivalent value may be, for example, a power value corresponding to the power consumption. When the power consumption sensor is used as the supply airflow volume detection unit  37  and the exhaust airflow volume detection unit  38 , the following data will be stored in the storage unit  362  in advance as the target supply airflow volume and the target exhaust airflow volume. Specifically, the storage unit  362  stores in advance data that associates the multi-level number of revolutions of the supply air motor implementing the target supply airflow volume with the power value corresponding to the number of revolutions. In addition, the storage unit  362  stores in advance data that associates the multi-level number of revolutions of the exhaust air motor implementing the target exhaust airflow volume with the power value corresponding to the number of revolutions. 
     When the airflow volume of the ventilation device  30  decreases, the following processing may be executed. The control unit  36  acquires the power consumption of the supply air motor from the supply airflow volume detection unit  37 , and acquires the power consumption of the exhaust motor from the exhaust airflow volume detection unit  38 . When the power consumption is less than the power value associated with the current number of revolutions beyond the predetermined range, the CPU  361  of the control unit  36  determines whether the power consumption is equal to or less than the lower limit value. When the power consumption is not equal to or less than the lower limit value, the CPU  361  increases the number of revolutions of the supply air fan  34  and the exhaust fan  35 . When the power consumption is equal to or less than the lower limit value, the air conditioning and ventilating system S of the present modification executes the processing of step S 107 , step S 112 , and below in  FIG. 5 . 
     MODIFICATION 4 
     In the air conditioning and ventilating system S in modification  4 , when the CPU  361  of the control unit  36  determines that at least one of the supply airflow volume and the exhaust airflow volume is equal to or less than the lower limit value, the CPU  401  of the central controller  40  may prohibit the operation manipulation of the indoor unit  20  with the remote controller  50 . In more detail, when the CPU  361  of the control unit  36  determines that at least one of the supply airflow volume and the exhaust airflow volume is equal to or less than the lower limit value, the CPU  401  of the central controller  40  prohibits the operation manipulation of the indoor unit  20  with the remote controller  50 . This prevents, for example, the user from operating the indoor unit  20  even though the ventilation device  30  has a fault and needs maintenance. As a result, it is possible to urge maintenance more reliably for solving the fault of the ventilation device  30 . 
     In addition, when the solution information is input, the CPU  401  of the central controller  40  may permit the operation manipulation of the indoor unit  20  with the remote controller  50 . The solution information can be input into the remote controller  50 , for example, by the service technician who confirms that the fault of the ventilation device  30  has been solved switching the remote controller  50  to the maintenance mode in which only the service technician can confirm the input. 
     [Action and Effect of the Present Embodiment] 
     Patent Literature 1 describes the operations of the ventilation device and the air conditioning device when the refrigerant actually leaks, but does not disclose securing the airflow volume of the ventilation device as a safety device in case the refrigerant leaks. An object of the present disclosure is to provide an air conditioning and ventilating system that can inhibit the shortage of airflow volume of the ventilation device when the refrigerant leaks. 
     In the present disclosure, on determination that the airflow volume equivalent value of the ventilation device  30  is equal to or less than the first predetermined value, the CPU  401  of the central controller  40  sets the operation of the air conditioning device A to the stop state. This makes it possible to inhibit the shortage of the airflow volume of the ventilation device  30  if the refrigerant leaks. Note that setting the operation of the air conditioning device A to the stop state means setting the operation of the compressor  13  of the outdoor unit  10  to the stop state. 
     In addition, in the present disclosure, the CPU  361  of the control unit  36  executes the fixed airflow volume control that adjusts the number of revolutions of the supply air fan  34  and the exhaust fan  35  to cause the supply airflow volume equivalent value and the exhaust airflow volume equivalent value to approach respective target values. When the CPU  361  of the control unit  36  determines that at least one of the supply airflow volume equivalent value and the exhaust airflow volume equivalent value is equal to or less than the first predetermined value during the fixed airflow volume control, the CPU  401  of the central controller  40  sets the operation of the air conditioning device A to the stop state. This makes it possible to inhibit the shortage of the airflow volume of the ventilation device  30  if the refrigerant leaks. In addition, the CPU  401  of the central controller  40  sets the operation of the air conditioning device A to the stop state, and causes the display unit  51  of the remote controller  50  to issue an alarm. It is possible to notify the service technician or user of the fault of the ventilation device and take measures to solve the fault. 
     In addition, in the present disclosure, when the CPU  361  of the control unit  36  determines that at least one of the supply airflow volume equivalent value and the exhaust airflow volume equivalent value is greater than the first predetermined value and equal to or less than the second predetermined value greater than the first predetermined value, the CPU  401  of the central controller  40  causes the display unit  51  of the remote controller  50  to issue an advance alarm. This makes it possible to notify the service technician or user of the fault of the ventilation device and take measures to solve the fault before the forced stop of the air conditioning device A in operation. 
     In addition, in the present disclosure, when the CPU  361  of the control unit  36  determines that at least one of the supply airflow volume equivalent value and the exhaust airflow volume equivalent value is equal to or less than the first predetermined value, the CPU  401  of the central controller  40  prohibits the operation manipulation of the air conditioning device A with the remote controller  50 . This prevents, for example, the user from operating the air conditioning device A even though the ventilation device  30  has a fault and needs maintenance, and as a result, it is possible to urge maintenance more reliably for solving the fault of the ventilation device  30 . 
     In addition, in the present disclosure, when the CPU  361  of the control unit  36  determines that at least one of the supply airflow volume equivalent value and the exhaust airflow volume equivalent value is greater than the first predetermined value and equal to or less than the second predetermined value greater than the first predetermined value, the CPU  401  of the central controller  40  activates the auxiliary fan  60 . By activating the auxiliary fan  60 , it is possible to compensate for the reduced airflow volume of the ventilation device  30 . 
     In addition, in the present disclosure, when the CPU  361  of the control unit  36  determines that at least one of the sum of the supply airflow volume equivalent value and the supply airflow volume equivalent value of the auxiliary fan and the sum of the exhaust airflow volume equivalent value and the exhaust airflow volume equivalent value of the auxiliary fan is equal to or less than the first predetermined value, the CPU  401  of the central controller  40  sets the operation of the air conditioning device A to the stop state. By setting the operation of the air conditioning device A to the stop state when at least one of the sum of the supply airflow volume equivalent value and the sum of the exhaust airflow volume equivalent value cannot secure the first predetermined value even with the assistance of the airflow volume by the auxiliary fan  60 , it is possible to notify the service technician or user that normal ventilation airflow volume is not secured and to urge the solution of the fault of the ventilation device  30 . This makes it possible to inhibit the shortage of the airflow volume of the ventilation device  30  if the refrigerant leaks. 
     In addition, in the present disclosure, the supply airflow volume by the supply air fan  34  and the exhaust airflow volume by the exhaust fan  35  are determined based on the number of revolutions and power consumption of the supply air fan  34  and the number of revolutions and power consumption of the exhaust fan  35 , respectively. By using the airflow volume determined based on the number of revolutions and the power consumption of the fan, it is possible to determine whether the airflow volume is equal to or less than the first predetermined value. 
     OTHER MODIFICATIONS 
     The present disclosure is not limited to the above-described embodiment, and various modifications may be made within the scope of the claims. 
     For example, in the above-described embodiment, the number of outdoor units is one, but two or more outdoor units can be adopted. The number and arrangement of the outdoor unit, the indoor unit, and the ventilation device are not particularly limited in the present disclosure, and can be appropriately selected to constitute the air conditioning and ventilating system. 
     In addition, in the above-described embodiment, when at least one of the supply airflow volume and the exhaust airflow volume becomes equal to or less than the lower limit, the CPU  401  of the central controller  40  sets the operation of the air conditioning device A to the stop state, but the present disclosure is not limited to this example. When both the supply airflow volume and the exhaust airflow volume becomes equal to or less than the lower limit, the CPU  401  may set the operation of the air conditioning device A to the stop state. The same applies to the case where the auxiliary fan  60  is provided in modification 1. 
     In addition, in the above-described embodiment, the supply airflow volume and the exhaust airflow volume are obtained from the airflow volume sensor or from the power consumption and the number of revolutions of the motors of the supply air fan and the exhaust fan, but the present disclosure is not limited to this example, and the ventilation airflow volume can be obtained by other methods. For example, the ventilation airflow volume can be obtained from the cross-sectional area of the duct where air is supplied or exhausted and the wind speed of the wind flowing through the duct detected by the sensor. In addition, it is also possible to pass air through a nozzle whose cross-sectional area is known in advance and to obtain the airflow volume flowing through the nozzle based on the pressure difference (pressure drop) between an inlet and outlet of the nozzle. 
     In addition, in the above-described embodiment, the orthogonal total heat exchanger is disposed in the ventilation device, but a rotary total heat exchanger that recovers heat from the return air by rotating a rotor can also be adopted. In addition, the adoption of such a total heat exchanger in the ventilation device can also be omitted. 
     In addition, in the above-described embodiment, the auxiliary fan  60  includes the auxiliary supply air fan that supplies air into the room and the auxiliary exhaust fan that discharges air from the room, but instead of these fans, only the auxiliary supply air fan that supplies air into the room may be provided, or only the auxiliary exhaust fan that exhausts air from the room can be provided. 
     In addition, in the above-described embodiment, the display unit of the remote controller functions as an alarm unit to issue an alarm with text information, symbol, and the like, but in addition to the visual alarm, or along with the visual alarm, a voice alarm that appeals to the auditory sense can be used. 
     REFERENCE SIGNS LIST 
       10  outdoor unit 
       11  liquid refrigerant pipe 
       12  gas refrigerant pipe 
       13  compressor 
       14  four-way switching valve 
       15  outdoor heat exchanger 
       16  outdoor expansion valve 
       17  liquid shutoff valve 
       18  gas shutoff valve 
       19  outdoor fan 
       20  indoor unit 
       21  indoor expansion valve 
       22  indoor heat exchanger 
       23  indoor fan 
       24  refrigerant sensor 
       25  control unit 
       30  ventilation device 
       31  supply air duct 
       32  return air duct 
       33  total heat exchanger 
       34  supply air fan 
       35  exhaust fan 
       36  control unit 
       37  supply airflow volume detection unit 
       38  exhaust airflow volume detection unit 
       40  central controller 
       50  remote controller 
       51  display unit 
       52  control unit 
       53  input unit 
       60  auxiliary fan 
       61  auxiliary supply air fan 
       62  auxiliary exhaust fan 
       63  blast duct 
       64  blast duct 
       65  electric damper 
       66  electric damper 
       67  control unit 
       251  CPU 
       252  storage unit 
       253  transmission and reception unit 
       361  CPU 
       362  storage unit 
       363  transmission and reception unit 
       401  CPU 
       402  storage unit 
       403  transmission and reception unit 
       411  CPU 
       412  storage unit 
       413  transmission and reception unit 
       521  CPU 
       522  storage unit 
       523  transmission and reception unit 
       671  CPU 
       672  storage unit 
       673  transmission and reception unit 
     A air conditioning device 
     R room (air conditioned space)