Air conditioner and air conditioning system

Abstract

Provided is an air conditioner, in which an air supply blower generates an air supply flow that flows from the inside of a housing toward the inside of a room. A refrigerant heat exchanger exchanges heat between a refrigerant and the air supply flow as a result of the air supply flow passing through the refrigerant heat exchanger. A semiconductor gas sensor is disposed downstream of the refrigerant heat exchanger in the supply air flow. The gas sensor can measure the concentration of the refrigerant in the air supply flow by means of energization of the gas sensor. If the gas sensor measurement results are at least a set reference value, a control unit detects that there is leakage of the refrigerant from the refrigerant heat exchanger and stops energization of the gas sensor.

Description

Air conditioner and air conditioning system

[0001] The present disclosure relates to an air conditioner and an air conditioning system.

[0002] In a conventional air conditioner, a semiconductor gas sensor may be used to detect leakage of a flammable refrigerant. The semiconductor gas sensor is a sensor that utilizes the properties of metal oxides. In the semiconductor gas sensor, when the refrigerant gas to be measured touches the metal oxide, oxygen in the metal oxide combines with the components of the refrigerant gas, causing a change in the resistance value of the metal oxide. Thereby, the concentration of the refrigerant gas in the air is measured.

[0003] When the semiconductor gas sensor measures the concentration of the refrigerant gas in the air, the metal oxide is heated by energizing a heater built in the gas sensor in order to activate the combination of oxygen in the metal oxide and the components of the refrigerant gas. In the semiconductor gas sensor, the longer the heating time of the gas sensor, the more the metal oxide deteriorates.

[0004] Patent Document 1 discloses an air conditioner that suppresses energization of a semiconductor gas sensor when an indoor fan is operating at a rotation speed at which leaked refrigerant can diffuse in order to suppress deterioration of the semiconductor gas sensor.

[0005] Japanese Patent Application Laid-Open No. 2017-172910

[0006] In the conventional air conditioner disclosed in Patent Document 1, not only is it difficult to suppress energization of the gas sensor depending on the operation of the indoor fan, but there is also a possibility that energization of the gas sensor continues even after leakage of the refrigerant is detected. For this reason, there is a risk that deterioration of the gas sensor progresses, and there is a risk that the frequency of replacement work of the gas sensor by an operator is not reduced. As a result, it is not possible to reduce the burden of the replacement work of the gas sensor by the operator.

[0007] The present disclosure solves the above problems, and an object thereof is to provide an air conditioner and an air conditioning system capable of reducing the burden of replacement work of a gas sensor by an operator.

[0008] The air conditioning system according to this disclosure comprises a housing, an air supply fan that generates an airflow that flows from the inside of the housing into the room, a refrigerant heat exchanger located inside the housing which performs heat exchange between the refrigerant and the airflow as the airflow passes through it, a semiconductor gas sensor located downstream of the refrigerant heat exchanger in the airflow, and a control unit that controls the supply of power to the gas sensor. When power is supplied to the gas sensor, it becomes possible to measure the concentration of the refrigerant in the airflow. If the measurement result of the gas sensor is above a set reference value, the control unit detects a leak of refrigerant from the refrigerant heat exchanger and stops the supply of power to the gas sensor.

[0009] According to this disclosure, it is possible to reduce the burden on workers when it comes to replacing gas sensors.

[0010] This is a configuration diagram showing an air conditioning device according to Embodiment 1. This is a flowchart showing the control of the power supply to the gas sensor by the control unit in Figure 1. This is a configuration diagram showing an air conditioning device according to Embodiment 2. This is a configuration diagram showing an air conditioning system according to Embodiment 3. This is a configuration diagram showing a first example of a processing circuit that realizes the functions of the control unit according to Embodiments 1 to 3. This is a configuration diagram showing a second example of a processing circuit that realizes the functions of the control unit according to Embodiments 1 to 3.

[0011] The embodiments for carrying out the subject matter of this disclosure will be described with reference to the attached figures. In each figure, the same or corresponding parts are denoted by the same reference numerals, and redundant explanations are simplified or omitted as appropriate. The subject matter of this disclosure is not limited to the following embodiments, and any modification of any component of the embodiments or omission of any component of the embodiments is possible without departing from the spirit of this disclosure.

[0012] Embodiment 1. Figure 1 is a configuration diagram showing an air conditioning system according to Embodiment 1. The air conditioning system 10 includes an air conditioning system body 1, a control unit 2, and an alarm 3.

[0013] The air conditioning unit 1 comprises a housing 4, an air supply fan 5, an exhaust fan 6, a total heat exchanger 7, a refrigerant heat exchanger 8, and a gas sensor 9. The air supply fan 5, exhaust fan 6, total heat exchanger 7, refrigerant heat exchanger 8, and gas sensor 9 are located inside the housing 4.

[0014] The housing 4 is provided with an outdoor intake port 41, an indoor outlet port 42, an indoor intake port 43, and an outdoor outlet port 44. In this embodiment, the housing 4 has the shape of a rectangular parallelepiped. In this embodiment, of the pair of end faces in the longitudinal direction of the housing 4, the outdoor intake port 41 and the outdoor outlet port 44 are provided on one end face, and the indoor outlet port 42 and the indoor intake port 43 are provided on the other end face.

[0015] Inside the housing 4, an air intake passage 45 and an exhaust passage 46 are formed. The air intake passage 45 runs from the outdoor side intake port 41, through the total heat exchanger 7 and the refrigerant heat exchanger 8 in sequence, to the indoor side outlet port 42. The exhaust passage 46 runs from the indoor side intake port 43, through the total heat exchanger 7, to the outdoor side outlet port 44.

[0016] An outdoor intake duct 11 that reaches the outdoors 15 is connected to the outdoor intake port 41. An indoor discharge duct 12 that reaches the indoors 16 is connected to the indoor outlet port 42. An indoor intake duct 13 that reaches the indoors 16 is connected to the indoor intake port 43. An outdoor discharge duct 14 that reaches the outdoors 15 is connected to the outdoor outlet port 44.

[0017] The air supply fan 5 is located in the air supply passage 45. In this embodiment, the air supply fan 5 is located in the air supply passage 45 between the total heat exchanger 7 and the refrigerant heat exchanger 8.

[0018] The supply air blower 5 generates an airflow. Due to the operation of the supply air blower 5, the airflow is drawn from the outside 15 through the outdoor intake duct 11 and the outdoor intake port 41 in sequence into the interior of the housing 4, and then flows from the inside of the housing 4 through the indoor outlet port 42 and into the indoor discharge duct 12 toward the interior 16. Inside the housing 4, the airflow flows through the airflow passage 45. As the airflow flows through the airflow passage 45 inside the housing 4, it passes through the total heat exchanger 7 and the refrigerant heat exchanger 8 in that order.

[0019] The air supply fan 5 has an air supply fan and an air supply fan motor. The air supply fan motor rotates the air supply fan when power is supplied to the air supply fan motor. When the air supply fan rotates, the air from the outdoors 15 is drawn in as outside air OA (Outdoor Air) from the outdoors 15 through the outdoor intake duct 11 and the outdoor intake port 41 in sequence and into the air supply passage 45. The outside air OA drawn into the air supply passage 45 flows through the air supply passage 45 as an air supply flow and is then supplied to the indoor 16 as supply air SA (Supply Air) from the indoor outlet 42 through the indoor discharge duct 12.

[0020] The exhaust fan 6 is located in the exhaust air passage 46. In this embodiment, the exhaust fan 6 is located in the exhaust air passage 46 between the total heat exchanger 7 and the outdoor side outlet 44.

[0021] The exhaust fan 6 generates an exhaust flow. Due to the operation of the exhaust fan 6, the exhaust flow is drawn into the interior of the housing 4 by sequentially passing from the room 16 through the indoor intake duct 13 and the indoor intake port 43, and then flows from the inside of the housing 4 through the outdoor outlet port 44 towards the outside 15 through the outdoor discharge duct 14. Inside the housing 4, the exhaust flow flows through the exhaust air passage 46. When the exhaust flow flows through the exhaust air passage 46 inside the housing 4, it passes through the total heat exchanger 7.

[0022] The exhaust fan 6 has an exhaust fan and an exhaust fan motor. The exhaust fan motor rotates the exhaust fan when power is supplied to the exhaust fan motor. When the exhaust fan rotates, the air from the room 16 is drawn in as return air RA from the room 16 through the indoor intake duct 13 and the indoor intake port 43 into the exhaust air passage 46. The return air RA drawn into the exhaust air passage 46 flows through the exhaust air passage 46 as exhaust air, and is then discharged to the outdoors 15 as exhaust air EA through the outdoor outlet 44 and the outdoor discharge duct 14.

[0023] The total heat exchanger 7 performs total heat exchange between the supply airflow before it passes through the refrigerant heat exchanger 8 inside the housing 4 and the exhaust airflow that flows through the exhaust air passage 46 inside the housing 4. Total heat exchange is a heat exchange in which sensible heat and latent heat are exchanged between two airflows. Therefore, the total heat exchanger 7 exchanges sensible heat and latent heat between the supply airflow and the exhaust airflow. Total heat exchange between the supply airflow and the exhaust airflow is performed by the supply airflow and the exhaust airflow passing through the total heat exchanger 7. This makes it possible to exchange the air inside the room 16 with the air outside 15 while suppressing the change in the temperature and humidity of the air inside the room 16 due to the temperature and humidity of the air outside 15.

[0024] The refrigerant flows through the refrigerant heat exchanger 8. The refrigerant heat exchanger 8 performs heat exchange between the supply airflow, which has passed through the total heat exchanger 7 inside the housing 4, and the refrigerant. Heat exchange between the supply airflow and the refrigerant occurs as the supply airflow passes through the refrigerant heat exchanger 8 through which the refrigerant flows. This enables air conditioning in the room 16.

[0025] Therefore, in this embodiment, the air conditioning system 10 is an air conditioning system with a supply and exhaust ventilation function that performs air conditioning in the room 16 while forcibly generating a supply airflow that flows from the outdoors 15 to the room 16 and an exhaust airflow that flows from the room 16 to the outdoors 15.

[0026] The refrigerant flowing through the refrigerant heat exchanger 8 circulates through a refrigerant circuit (not shown). The refrigerant circuit includes a compressor, an outdoor heat exchanger, an expansion valve, and an indoor heat exchanger. The refrigerant heat exchanger 8 is provided in the refrigerant circuit as an indoor heat exchanger. In the refrigerant circuit, the compressor is driven, causing the refrigerant to circulate through the compressor, outdoor heat exchanger, expansion valve, and indoor heat exchanger while undergoing phase changes.

[0027] The operation of the air conditioning system 10 can be switched between heating and cooling operation by the operation of a solenoid valve (not shown) provided in the refrigerant circuit. In the refrigerant heat exchanger 8, when the air conditioning system 10 is in heating operation, the refrigerant is released from the refrigerant into the supply airflow, causing it to condense. Also, in the refrigerant heat exchanger 8, when the air conditioning system 10 is in cooling operation, the refrigerant absorbs heat from the supply airflow, causing it to evaporate. Therefore, in the air conditioning system 10, the refrigerant heat exchanger 8 acts as a condenser during heating operation and as an evaporator during cooling operation.

[0028] The refrigerant flowing through the refrigerant heat exchanger 8 is a flammable refrigerant. R32, R290, and other similar refrigerants are used in the refrigerant heat exchanger 8.

[0029] A gas sensor 9 is located inside the housing 4 to monitor whether or not refrigerant leakage has occurred from the refrigerant heat exchanger 8. The gas sensor 9 is located downstream of the refrigerant heat exchanger 8 in the supply airflow. In this embodiment, the gas sensor 9 is located between the refrigerant heat exchanger 8 and the indoor side outlet 42 in the supply air passage 45. As a result, if refrigerant leaks from the refrigerant heat exchanger 8, the gaseous refrigerant is diffused from the refrigerant heat exchanger 8 into the supply airflow, and the supply airflow containing the gaseous refrigerant flows through the location of the gas sensor 9.

[0030] The gas sensor 9 is a semiconductor-type gas sensor. Therefore, the gas sensor 9 measures the concentration of refrigerant in the supply airflow by utilizing the properties of metal oxide semiconductors. The gas sensor 9 can measure the concentration of refrigerant in the supply airflow when power is supplied to the gas sensor 9.

[0031] The gas sensor 9 comprises a sensor body and a heating unit. In the gas sensor 9, the heating unit heats the sensor body when power is supplied to the gas sensor 9. The sensor body of the gas sensor 9 has a metal oxide semiconductor. The gas sensor 9 can measure the concentration of refrigerant in the supply airflow when the metal oxide semiconductor of the sensor body is heated.

[0032] Metal oxide semiconductors have the property that their electrical resistance changes when a flammable gas, which is a reducing gas, comes into contact with them. This property of metal oxide semiconductors is activated when the metal oxide semiconductor is heated.

[0033] Since the refrigerant flowing through the refrigerant heat exchanger 8 is flammable, when the sensor body is heated and refrigerant leaking from the refrigerant heat exchanger 8 comes into contact with the metal oxide semiconductor of the sensor body, the electrical resistance of the metal oxide semiconductor changes. Therefore, the electrical resistance of the metal oxide semiconductor in the sensor body changes according to the concentration of the refrigerant in the supply airflow. The gas sensor 9 measures the concentration of the refrigerant in the supply airflow by generating a signal as a sensor signal corresponding to the change in the electrical resistance of the metal oxide semiconductor in the sensor body.

[0034] The control unit 2 controls the operation of the supply air blower 5 and the exhaust air blower 6, respectively. The control unit 2 also controls the operation of the air conditioning system 10 for both heating and cooling modes. Furthermore, the control unit 2 controls the power supply to the gas sensor 9. In this embodiment, the control unit 2 is mounted on the housing 4.

[0035] The control unit 2 has a preset reference value indicating the refrigerant concentration that serves as the standard for detecting refrigerant leakage. The control unit 2 is capable of receiving sensor signals from the gas sensor 9. The control unit 2 compares the measurement result of the gas sensor 9, which is the refrigerant concentration based on the sensor signal from the gas sensor 9, with the preset reference value to determine whether the measurement result of the gas sensor 9 is equal to or greater than the preset reference value. If the measurement result of the gas sensor 9 is equal to or greater than the preset reference value, the control unit 2 detects refrigerant leakage from the refrigerant heat exchanger 8. If the measurement result of the gas sensor 9 is lower than the preset reference value, the control unit 2 does not detect refrigerant leakage from the refrigerant heat exchanger 8.

[0036] When control unit 2 does not detect a refrigerant leak, it continues to supply power to the gas sensor 9. When control unit 2 detects a refrigerant leak, it stops supplying power to the gas sensor 9.

[0037] In the gas sensor 9, the longer the power is supplied to the gas sensor 9, the more the sensor body is heated, leading to deterioration of the gas sensor 9. Therefore, in the air conditioning system 10, the power supply to the gas sensor 9 is stopped when the control unit 2 detects a refrigerant leak, thereby suppressing the deterioration of the gas sensor 9.

[0038] The alarm device 3 is controlled by the control unit 2. When the control unit 2 detects a refrigerant leak, it causes the alarm device 3 to emit an alarm indicating that a refrigerant leak has been detected. The alarm emitted by the alarm device 3 may include information indicating that power to the gas sensor 9 has been cut off. In this embodiment, the alarm device 3 is located at a distance from the air conditioning unit body 1.

[0039] The alarm device 3 may be a display unit that shows an alarm, or a sound generator that emits an alarm sound. The alarm device 3 may also have both a display unit and a sound generator. A display, lamp, etc., can be used as the display unit. A speaker, buzzer, etc., can be used as the sound generator. When the alarm device 3 emits an alarm, people in the vicinity of the alarm device 3 will be able to recognize that a refrigerant leak from the refrigerant heat exchanger 8 has been detected. This will prompt repair or inspection of the refrigerant heat exchanger 8.

[0040] When a worker performs repairs or inspections on the refrigerant heat exchanger 8, the power supply to the gas sensor 9 is already stopped, thus suppressing the deterioration of the gas sensor 9. Therefore, the worker does not need to replace the gas sensor 9 every time they perform repairs or inspections on the refrigerant heat exchanger 8.

[0041] After the control unit 2 generates an alarm in the alarm device 3, a reset operation is performed on the control unit 2, which stops the alarm from being generated by the alarm device 3. Also, after the control unit 2 stops the power supply to the gas sensor 9, a reset operation is performed on the control unit 2, which restores the power supply to the gas sensor 9.

[0042] Next, the control of energization to the gas sensor 9 by the control unit 2 will be described. FIG. 2 is a flowchart showing the control of energization to the gas sensor 9 by the control unit 2 of FIG. 1. When power supply to the air conditioner 10 is started in step S1, the control unit 2 energizes the gas sensor 9 in step S2. Thereby, the gas sensor 9 can measure the concentration of the refrigerant in the supply air flow.

[0043] After that, in step S3, the control unit 2 determines whether the measurement result of the gas sensor 9 is equal to or greater than the set reference value by comparing the measurement result of the gas sensor 9 with the set reference value.

[0044] If the measurement result of the gas sensor 9 in step S3 is less than the set reference value, the control unit 2 continues to energize the gas sensor 9 without detecting refrigerant leakage in step S4. After that, the control unit 2 repeats the processes of step S3 and step S4 until the measurement result of the gas sensor 9 becomes equal to or greater than the set reference value.

[0045] If the measurement result of the gas sensor 9 in step S3 is equal to or greater than the set reference value, the control unit 2 detects refrigerant leakage in step S5 and stops energizing the gas sensor 9. Thereby, heating of the sensor body in the gas sensor 9 is stopped, and deterioration of the gas sensor 9 is suppressed.

[0046] When the control unit 2 detects refrigerant leakage in step S5, the control unit 2 generates an alarm indicating that refrigerant leakage has been detected in the alarm device 3 in step S6. Thereby, it becomes possible for people around the alarm device 3 to recognize that the control unit 2 has detected refrigerant leakage from the refrigerant heat exchanger 8, and repair or inspection of the refrigerant heat exchanger 8 is promoted. After that, when repair or inspection of the refrigerant heat exchanger 8 is performed by an operator, a reset operation for the control unit 2 is performed by the operator.

[0047] After generating the alarm in the alarm device 3 in step S6, the control unit 2 determines in step S7 whether a reset operation for the control unit 2 has been performed.

[0048] When a reset operation on the control unit 2 is not performed in step S7, the control unit 2 repeatedly determines whether a reset operation on the control unit 2 has been performed until a reset operation on the control unit 2 is performed.

[0049] When a reset operation on the control unit 2 is performed in step S7, the control unit 2 stops the generation of an alarm by the alarm device 3 in step S8. Thereafter, the processing of the control unit 2 returns to step S2, and the control unit 2 releases the state in which the energization of the gas sensor 9 is stopped and energizes the gas sensor 9. As a result, the state of the gas sensor 9 returns to a state in which the concentration of the refrigerant in the supply air flow can be measured.

[0050] In such an air conditioner, a supply air flow generated by the supply air blower 5 flows from the inside of the housing 4 toward the room 16. Inside the housing 4, a refrigerant heat exchanger 8 that performs heat exchange between the refrigerant and the supply air flow as the supply air flow passes therethrough is provided. A semiconductor gas sensor 9 is disposed on the downstream side of the supply air flow with respect to the refrigerant heat exchanger 8. The gas sensor 9 can measure the concentration of the refrigerant in the supply air flow when the gas sensor 9 is energized. When the measurement result of the gas sensor 9 is equal to or greater than a set reference value, the control unit 2 detects a refrigerant leak and stops the energization of the gas sensor 9.

[0051] Therefore, it is possible to avoid the continuous energization of the gas sensor 9 even after the refrigerant leak is detected by the control unit 2. As a result, unnecessary energization of the gas sensor 9 can be reduced, and deterioration of the gas sensor 9 due to the energization of the gas sensor 9 can be suppressed.

[0052] In this case, if power is continuously supplied to the gas sensor 9 even after the control unit 2 has detected a refrigerant leak, the deterioration of the gas sensor 9 will progress further. Therefore, in this case, the worker will need to replace the gas sensor 9 with a new one each time they repair or inspect the refrigerant heat exchanger 8. However, in this embodiment, when the control unit 2 detects a refrigerant leak, power is stopped to the gas sensor 9, thus suppressing the deterioration of the gas sensor 9. As a result, the lifespan of the gas sensor 9 can be extended, and it can be used continuously without replacement. This reduces the frequency of gas sensor 9 replacement work performed by workers, thereby reducing the burden on workers.

[0053] Furthermore, when the control unit 2 detects a refrigerant leak, it generates an alarm on the alarm device 3 indicating that a refrigerant leak has been detected. This allows for more reliable notification of the refrigerant leak to people in the vicinity of the alarm device 3. As a result, measures such as repairs or inspections of the refrigerant heat exchanger 8 can be carried out more reliably, and the continued leakage of refrigerant from the refrigerant heat exchanger 8 can be more reliably prevented.

[0054] Furthermore, the supply airflow generated by the supply air blower 5 is drawn from the outdoors 15 into the interior of the enclosure 4, and then flows from the interior of the enclosure 4 towards the interior 16. The exhaust airflow generated by the exhaust air blower 6 is drawn from the interior of the interior 16 into the interior of the enclosure 4, and then flows from the interior of the enclosure 4 towards the outdoors 15. Therefore, the air conditioning system 10 can be an air conditioning system with a supply and exhaust ventilation function that forcibly generates a supply airflow that flows from the outdoors 15 towards the interior 16 and an exhaust airflow that flows from the interior 16 towards the outdoors 15. This makes it possible to efficiently ventilate the room by exchanging the air from the outdoors 15 with the air from the room 16 while simultaneously conditioned the air in the room 16.

[0055] Furthermore, the total heat exchanger 7 performs total heat exchange between the supply air flow before it passes through the refrigerant heat exchanger 8 inside the housing 4 and the exhaust air flowing inside the housing 4. Therefore, when ventilation is performed to exchange the air from the outdoors 15 with the air inside 16, not only sensible heat but also latent heat can be exchanged between the air from the outdoors 15 and the air inside 16. This makes it possible to suppress the increase in heat loss due to ventilation.

[0056] Embodiment 2. Figure 3 is a configuration diagram showing an air conditioning system according to Embodiment 2. The air conditioning system 20 includes an air conditioning system body 101, a control unit 102, and an alarm 103.

[0057] The air conditioning unit body 101 includes a housing 104, an air supply fan 105, a refrigerant heat exchanger 108, and a gas sensor 109. The air supply fan 105, the refrigerant heat exchanger 108, and the gas sensor 109 are located inside the housing 104.

[0058] The housing 104 is provided with an indoor intake port 143 and an indoor outlet port 142. An air supply passage 145 is formed inside the housing 104. The air supply passage 145 extends from the indoor intake port 143, through the refrigerant heat exchanger 8, to the indoor outlet port 142.

[0059] An indoor intake duct 113 that reaches the room 16 is connected to the indoor intake port 143. An indoor discharge duct 112 that reaches the room 16 is connected to the indoor outlet port 142.

[0060] The air supply fan 105 is located in the air supply passage 145. In this embodiment, the air supply fan 105 is located in the air supply passage 145 between the indoor side intake port 143 and the refrigerant heat exchanger 8.

[0061] The configuration of the air supply fan 105 is the same as that of the air supply fan 5 in Embodiment 1. The air supply flow is drawn into the interior of the housing 104 by the operation of the air supply fan 105, passing sequentially from the room 16 through the room intake duct 113 and the room intake port 143, and then flows from inside the housing 104 through the room outlet port 142 and into the room 16 through the room discharge duct 112. Inside the housing 104, the air supply flow flows through the air supply passage 145. When the air supply flow flows through the air supply passage 145 inside the housing 104, it passes through the refrigerant heat exchanger 108.

[0062] When the supply fan of the supply air blower 105 rotates, the air from the room 16 is drawn in as return air RA from the room 16 through the indoor intake duct 113 and the indoor intake port 143 into the supply air passage 145. The return air RA drawn into the supply air passage 145 flows through the supply air passage 145 as supply air flow, and is then supplied to the room 16 as supply air SA through the indoor outlet port 142 and the indoor discharge duct 112. Thus, in this embodiment, the air conditioning device 20 is an air circulation type air conditioning device that circulates air between the inside of the housing 4 and the room 16 by generating a supply air flow that is drawn in from the room 16 into the housing 4 and then flows from the inside of the housing 4 towards the room 16. Therefore, in this embodiment, the air conditioning device 20 does not have a ventilation function.

[0063] The configuration of the refrigerant heat exchanger 108 is the same as that of the refrigerant heat exchanger 8 in Embodiment 1. In the air conditioning system 20, the refrigerant flowing through the refrigerant heat exchanger 108 also circulates through the refrigerant circuit. The configuration of the refrigerant circuit in the air conditioning system 20 is the same as that of the refrigerant circuit in the air conditioning system 10. Furthermore, the refrigerant flowing through the refrigerant heat exchanger 108 is the same as the refrigerant flowing through the refrigerant heat exchanger 8 in Embodiment 1. Therefore, the refrigerant flowing through the refrigerant heat exchanger 108 is a flammable refrigerant.

[0064] A gas sensor 109 is located inside the housing 104 to monitor whether or not refrigerant leakage has occurred from the refrigerant heat exchanger 108. The gas sensor 109 is located downstream of the refrigerant heat exchanger 108 in the supply airflow. In this embodiment, the gas sensor 109 is located between the refrigerant heat exchanger 108 and the indoor side outlet 142 in the supply air passage 145. As a result, if refrigerant leaks from the refrigerant heat exchanger 108, the gaseous refrigerant is diffused from the refrigerant heat exchanger 108 into the supply airflow, and the supply airflow containing the gaseous refrigerant flows through the location of the gas sensor 109.

[0065] The configuration of the gas sensor 109 is the same as that of the gas sensor 9 in Embodiment 1. That is, the gas sensor 109 is a semiconductor type gas sensor. The gas sensor 109 can measure the concentration of refrigerant in the supply airflow when power is supplied to the gas sensor 109.

[0066] The control unit 102 controls the operation of the air supply fan 105. The control unit 102 also controls the operation of the air conditioning system 20 for heating and cooling operations, respectively. Furthermore, the control unit 102 controls the supply of power to the gas sensor 109. In this embodiment, the control unit 102 is mounted on the housing 104.

[0067] Similar to the control unit 2 in Embodiment 1, the control unit 102 has a preset reference value indicating the refrigerant concentration that serves as a standard for detecting refrigerant leakage. The control unit 102 is capable of receiving sensor signals from the gas sensor 109. The control unit 102 compares the measurement result of the gas sensor 109, which is the refrigerant concentration based on the sensor signal from the gas sensor 109, with the preset reference value to determine whether the measurement result of the gas sensor 109 is equal to or greater than the preset reference value. If the measurement result of the gas sensor 109 is equal to or greater than the preset reference value, the control unit 102 detects refrigerant leakage from the refrigerant heat exchanger 108. If the measurement result of the gas sensor 109 is lower than the preset reference value, the control unit 102 does not detect refrigerant leakage from the refrigerant heat exchanger 108.

[0068] The control of the power supply to the gas sensor 109 by the control unit 102 is the same as the control of the power supply to the gas sensor 9 by the control unit 2 in Embodiment 1. Therefore, when the control unit 102 does not detect a refrigerant leak, it continues to supply power to the gas sensor 109. Furthermore, when the control unit 102 detects a refrigerant leak, it stops supplying power to the gas sensor 109.

[0069] The configuration of the alarm 103 is the same as that of the alarm 3 in Embodiment 1. The alarm 103 is controlled by the control unit 102. The control of the alarm 103 by the control unit 102 is the same as the control of the alarm 3 by the control unit 2 in Embodiment 1. Therefore, when the control unit 102 detects a refrigerant leak, it causes the alarm 103 to generate an alarm indicating that a refrigerant leak has been detected. The alarm generated by the alarm 103 may include information indicating that the power supply to the gas sensor 109 has been stopped. In this embodiment, the alarm 103 is located away from the air conditioning unit body 101.

[0070] After the control unit 102 generates an alarm in the alarm device 103, a reset operation is performed on the control unit 102 to stop the alarm generation by the alarm device 103. Also, after the control unit 102 stops the power supply to the gas sensor 109, a reset operation is performed on the control unit 102 to restore power supply to the gas sensor 109. The other configurations are the same as in Embodiment 1.

[0071] Thus, by using an air circulation type air conditioning system as the air conditioning system 20, air conditioning in the room 16 can be efficiently performed. In addition, when the control unit 102 detects a refrigerant leak, it can stop the power supply to the gas sensor 109, thereby suppressing the deterioration of the gas sensor 109. This reduces the frequency of gas sensor 109 replacement work by workers, thereby reducing the burden on workers who perform gas sensor 109 replacement work.

[0072] Embodiment 3. Figure 4 is a configuration diagram showing an air conditioning system according to Embodiment 3. The air conditioning system has multiple air conditioning units, namely air conditioning units 10 and air conditioning units 20. The configuration of air conditioning unit 10 in this embodiment is the same as the configuration of air conditioning unit 10 in Embodiment 1. The configuration of air conditioning unit 20 in this embodiment is the same as the configuration of air conditioning unit 20 in Embodiment 2.

[0073] The indoor discharge duct 12 and indoor intake duct 13 connected to the housing 4 of the air conditioning unit 10, and the indoor discharge duct 112 and indoor intake duct 113 connected to the housing 104 of the air conditioning unit 20, all reach a common room 16. As a result, the supply airflow generated by the supply air blower 5 in the air conditioning unit 10 and the supply airflow generated by the supply air blower 105 in the air conditioning unit 20 flow toward the common room 16. In other words, the supply airflow generated in each of the multiple air conditioning units 10 and 20 flows toward the common room 16.

[0074] Therefore, if a refrigerant leak occurs in any of the air conditioning units 10 or 20, the refrigerant will flow into the common room 16. Accordingly, if either the control unit 2 or 102 in any of the air conditioning units 10 or 20 detects a refrigerant leak, monitoring for refrigerant leaks can be stopped in all air conditioning units 10 or 20 related to air conditioning in the common room 16.

[0075] The control unit 2 in the air conditioning unit 10 and the control unit 102 in the air conditioning unit 20 each have a communication unit (not shown). The communication units in each of the control units 2 and 102 are capable of communicating with each other wirelessly or via wired connections.

[0076] In each air conditioning unit 10, 20, when the control unit 2, 102 detects a refrigerant leak, the control unit 2, 102 that detected the refrigerant leak outputs a power-off command from the communication unit. Therefore, in air conditioning unit 10, when the control unit 2 detects a refrigerant leak, the control unit 2 that detected the refrigerant leak outputs a power-off command from the communication unit. In air conditioning unit 20, when the control unit 102 detects a refrigerant leak, the control unit 102 that detected the refrigerant leak outputs a power-off command from the communication unit.

[0077] In the air conditioning unit 10, when control unit 2 outputs a power-off command from the communication unit, the power-off command is transmitted to control unit 102, which is a control unit other than control unit 2 that detected the refrigerant leak. In the air conditioning unit 20, when control unit 102 outputs a power-off command from the communication unit, the power-off command is transmitted to control unit 2, which is a control unit other than control unit 102 that detected the refrigerant leak.

[0078] In each air conditioning unit 10, 20, when the control unit 2, 102 receives a power-off command from the communication unit, the control unit 2, 102 that received the power-off command stops the power supply to the gas sensors 9, 109. Therefore, in air conditioning unit 10, when the control unit 2 receives a power-off command from the communication unit, the control unit 2 that received the power-off command stops the power supply to the gas sensor 9. In air conditioning unit 20, when the control unit 102 receives a power-off command from the communication unit, the control unit 102 that received the power-off command stops the power supply to the gas sensor 109.

[0079] In this type of air conditioning system, the supply airflow generated in each air conditioning unit 10, 20 flows toward a common room 16. The control units 2, 102 in each air conditioning unit 10, 20 each have a communication unit. The communication units in each control unit 2, 102 are able to communicate with each other. In each air conditioning unit 10, 20, when the control unit 2, 102 detects a refrigerant leak, the control unit 2, 102 that detected the refrigerant leak outputs a power cut-off command from its communication unit. In each air conditioning unit 10, 20, when the control unit 2, 102 receives the power cut-off command via its communication unit, the control unit 2, 102 that received the power cut-off command cuts off the power supply to the gas sensors 9, 109.

[0080] Therefore, if either the control unit 2 or 102 in each air conditioning unit 10 or 20 detects a refrigerant leak, the power supply to the gas sensor in the air conditioning unit that detected the leak can be stopped, as can the power supply to the gas sensor in the air conditioning unit that did not detect a leak. In other words, if either the control unit 2 or 102 in each air conditioning unit 10 or 20 detects a refrigerant leak, the power supply to the gas sensors 9 and 109 in each air conditioning unit 10 or 20 that generate the supply airflow that flows toward the common room 16 can be stopped. This suppresses the deterioration of the gas sensors 9 and 109 in each air conditioning unit 10 or 20 that generate the supply airflow that flows toward the common room 16. Consequently, the frequency of replacement work for the gas sensors 9 and 109 in each air conditioning unit 10 or 20 can be reduced, and the burden on workers to replace the gas sensors 9 and 109 can be reduced.

[0081] Furthermore, in air conditioning unit 10, of the air conditioning units 10 and 20, the supply airflow generated by the supply air blower 5 is drawn from the outdoors 15 into the interior of the housing 4, and then flows from the interior of the housing 4 towards the indoor 16. Also in air conditioning unit 10, the exhaust airflow generated by the exhaust air blower 6 is drawn from the indoor 16 into the interior of the housing 4, and then flows from the interior of the housing 4 towards the outdoors 15. For this reason, air conditioning unit 10 can be an air conditioning unit with a supply and exhaust ventilation function. This makes it possible to forcibly generate a supply airflow that flows from the outdoors 15 towards the indoor 16 and an exhaust airflow that flows from the indoor 16 towards the outdoors 15, enabling efficient ventilation that exchanges the air from the outdoors 15 with the air from the indoor 16.

[0082] Furthermore, in air conditioning unit 10, one of the air conditioning units 10 and 20, a total heat exchanger 7 is installed inside the housing 4. The total heat exchanger 7 performs total heat exchange between the supply air flow before it passes through the refrigerant heat exchanger 8 inside the housing 4 and the exhaust air flowing inside the housing 4. Therefore, when air conditioning unit 10 performs ventilation to exchange the outdoor air 15 with the indoor air 16, it is possible to exchange not only sensible heat but also latent heat between the outdoor air 15 and the indoor air 16. This makes it possible to suppress the increase in heat loss due to ventilation.

[0083] Furthermore, in air conditioning unit 20, one of the air conditioning units 10 and 20, the supply airflow generated by the supply air blower 105 is drawn from the room 16 into the interior of the housing 4, and then flows from the interior of the housing 4 back to the room 16. For this reason, air circulation type air conditioning unit 20 can be used. This allows for efficient air conditioning in the room 16.

[0084] In embodiments 1 and 3, the air supply fan 5 is positioned between the total heat exchanger 7 and the refrigerant heat exchanger 8 in the air conditioning system 10. However, the position of the air supply fan 5 is not limited to this, as long as the air supply fan 5 generates an airflow in the air conditioning system 10. For example, in the air conditioning system 10, the air supply fan 5 may be positioned between the outdoor intake port 41 in the air supply passage 45 and the total heat exchanger 7.

[0085] Furthermore, in embodiments 1 and 3, the exhaust fan 6 in the air conditioning system 10 is positioned between the total heat exchanger 7 and the outdoor outlet 44. However, the position of the exhaust fan 6 is not limited to this, as long as the exhaust fan 6 generates an exhaust flow in the air conditioning system 10. For example, in the air conditioning system 10, the exhaust fan 6 may be positioned between the indoor intake port 43 and the total heat exchanger 7 in the exhaust air passage 46.

[0086] Furthermore, in embodiments 1 and 3, the total heat exchanger 7 is provided inside the housing 4 in the air conditioning unit 10. However, the total heat exchanger 7 is not required in the air conditioning unit 10. Even without the total heat exchanger 7 in the air conditioning unit 10, ventilation can be efficiently performed to exchange the indoor air 16 with the outdoor air 15.

[0087] Furthermore, in embodiments 1 and 3, the air conditioning unit 10 has an exhaust fan 6 and a total heat exchanger 7 installed inside the housing 4. However, the air conditioning unit 10 does not need to have an exhaust fan 6 and a total heat exchanger 7. In this case, the housing 4 does not have an indoor intake port 43 and an outdoor outlet port 44, and only an air supply passage 45 is formed inside the housing 4. As a result, in this case, no exhaust flow is generated in the air conditioning unit 10, and only an air supply flow is generated by the air supply fan 5, which flows from the outside 15 into the housing 4 and then from the inside of the housing 4 towards the room 16. That is, the air conditioning unit 10 may be an air conditioning unit with an air supply ventilation function that performs air conditioning in the room 16 while forcibly generating an air supply flow that flows from the outside 15 towards the room 16.

[0088] Thus, even if the air conditioning unit 10 is an air conditioning unit with a supply air ventilation function, the control unit 2 can stop the power supply to the gas sensor 9 when it detects a refrigerant leak. This makes it possible to suppress the deterioration of the gas sensor 9 in the air conditioning unit 10 and reduce the burden on workers in replacing the gas sensor 9. In addition, by forcibly generating a supply airflow that flows from the outdoors 15 to the indoors 16, natural exhaust from the indoors 16 to the outdoors 15 can be generated, and ventilation can be performed to exchange the air in the indoors 16 with the air in the outdoors 15.

[0089] Furthermore, in Embodiment 3, there are two air conditioning units that generate the supply airflow directed toward the common room 16: air conditioning unit 10 and air conditioning unit 20. However, the number of air conditioning units that generate the supply airflow directed toward the common room 16 may be multiple, and may be three or more. In this case, the control unit in each air conditioning unit has a communication unit, and each communication unit is capable of communicating with each other. In this case, when the control unit in each air conditioning unit detects a refrigerant leak, the control unit that detected the refrigerant leak outputs a power-off command from the communication unit. Furthermore, in this case, when the control unit in each air conditioning unit receives the power-off command via the communication unit, the control unit that received the power-off command stops the power supply to the gas sensor. Therefore, even in this manner, if at least one of the control units in each air conditioning unit detects a refrigerant leak, the power supply to each of the gas sensors in each air conditioning unit can be stopped, thereby suppressing the deterioration of all gas sensors in each air conditioning unit. Consequently, the burden on workers for the replacement of all gas sensors in each air conditioning unit can be reduced.

[0090] Furthermore, in Embodiment 3, if there are multiple air conditioning units that generate a supply airflow directed toward a common room 16, at least one of the multiple air conditioning units can be an air conditioning unit with a supply and exhaust ventilation function having the same configuration as air conditioning unit 10. Therefore, for example, all of the multiple air conditioning units may be air conditioning units with a supply and exhaust ventilation function having the same configuration as air conditioning unit 10. If at least one of the multiple air conditioning units is an air conditioning unit with a supply and exhaust ventilation function, the air conditioning unit with a supply and exhaust ventilation function does not need to have a total heat exchanger 7.

[0091] Furthermore, in Embodiment 3, if there are multiple air conditioning units that generate a supply airflow directed toward a common room 16, at least one of the multiple air conditioning units can be an air conditioning unit with a supply air ventilation function. Therefore, for example, all of the multiple air conditioning units may be air conditioning units with a supply air ventilation function.

[0092] Furthermore, in Embodiment 3, if there are multiple air conditioning units that generate a supply airflow directed toward a common room 16, at least one of the multiple air conditioning units can be an air-circulating type air conditioning unit having the same configuration as air conditioning unit 20. Therefore, for example, all of the multiple air conditioning units may be air-circulating type air conditioning units having the same configuration as air conditioning unit 20.

[0093] Furthermore, the functions of the control units 2 and 102 according to each of the above embodiments are realized by processing circuits. Figure 5 is a configuration diagram showing a first example of a processing circuit that realizes the functions of the control units 2 and 102 according to embodiments 1 to 3. The processing circuit 100 in the first example is dedicated hardware.

[0094] Furthermore, the processing circuit 100 may be, for example, a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC (Application Specific Integrated Circuit), an FPGA (Field Programmable Gate Array), or a combination thereof.

[0095] Figure 6 is a configuration diagram showing a second example of a processing circuit that realizes the functions of the control units 2 and 102 according to embodiments 1 to 3. The processing circuit 200 of the second example includes a processor 201 and a memory 202.

[0096] In the processing circuit 200, the functions of the control units 2 and 102 are realized by software, firmware, or a combination of software and firmware. The software and firmware are written as programs and stored in the memory 202. The processor 201 realizes the functions of the control units 2 and 102 by reading and executing the programs stored in the memory 202.

[0097] A program stored in memory 202 can be said to cause the computer to execute the procedures or methods described above. Here, memory 202 refers to non-volatile or volatile semiconductor memory such as RAM (Random Access Memory), ROM (Read Only Memory), flash memory, EPROM (Erasable Programmable Read Only Memory), and EEPROM (Electrically Erasable and Programmable Read Only Memory). Magnetic disks, flexible disks, optical disks, compact disks, minidiscs, DVDs, etc., also fall under the category of memory 202.

[0098] Furthermore, some of the functions of the control unit 2, 102 described above may be implemented using dedicated hardware, while others may be implemented using software or firmware.

[0099] Thus, the processing circuit can realize the above-described functions of the control unit 2, 102 through hardware, software, firmware, or a combination thereof.

[0100] The configurations shown in the embodiments described above are merely examples of the content of this disclosure. The embodiments can be combined with other known technologies. Some parts of the configurations of the embodiments can be omitted or modified without departing from the gist of this disclosure.

[0101] 2, 102 Control unit, 3, 103 Alarm, 4, 104 Housing, 5, 105 Supply air blower, 6 Exhaust blower, 7 Total heat exchanger, 8, 108 Refrigerant heat exchanger, 9, 109 Gas sensor, 10, 20 Air conditioning unit, 15 Outdoor, 16 Indoor.

Claims

1. An air conditioning system comprising: a housing; an air supply fan that generates an airflow that flows from the inside of the housing toward a room; a refrigerant heat exchanger provided inside the housing, which performs heat exchange between the refrigerant and the airflow as the airflow passes through it; a semiconductor gas sensor located downstream of the refrigerant heat exchanger in the airflow; and a control unit that controls the supply of power to the gas sensor, wherein the gas sensor can measure the concentration of the refrigerant in the airflow when power is supplied to the gas sensor, and the control unit detects refrigerant leakage from the refrigerant heat exchanger and stops supplying power to the gas sensor if the measurement result of the gas sensor is above a set reference value.

2. The air conditioning system according to claim 1, comprising an alarm, wherein the control unit, upon detecting a refrigerant leak, generates an alarm on the alarm indicating that a refrigerant leak has been detected.

3. An air conditioning system comprising a plurality of air conditioning units, each of which is an air conditioning unit according to claim 1 or claim 2, wherein the supply airflow generated in each of the plurality of air conditioning units flows toward a common room, the control unit in each of the plurality of air conditioning units has a communication unit, each of the communication units is able to communicate with each other, and in each of the plurality of air conditioning units, when the control unit detects a refrigerant leak, the control unit that detected the refrigerant leak outputs a power cut-off command from the communication unit, and in each of the plurality of air conditioning units, when the control unit receives the power cut-off command via the communication unit, the control unit that received the power cut-off command cuts off power to the gas sensor.

4. The air conditioning system according to claim 3, wherein at least one of the plurality of air conditioning units is an air conditioning unit with a supply and exhaust ventilation function, wherein in the air conditioning unit with a supply and exhaust ventilation function, the supply airflow generated by the supply air blower is drawn from the outside into the inside of the housing and then flows from the inside of the housing toward the inside of the room, and the air conditioning unit with a supply and exhaust ventilation function is equipped with an exhaust blower, and the exhaust blower generates an exhaust airflow that is drawn from the inside of the room into the inside of the housing and then flows from the inside of the housing toward the outside.

5. The air conditioning system according to claim 4, wherein the air conditioning device with a supply and exhaust ventilation function comprises a total heat exchanger provided inside the housing, and the total heat exchanger performs total heat exchange between the supply airflow before it passes through the refrigerant heat exchanger inside the housing and the exhaust airflow flowing inside the housing.

6. The air conditioning system according to claim 3, wherein at least one of the plurality of air conditioning units is an air conditioning unit with a supply air ventilation function, and in the air conditioning unit with a supply air ventilation function, the supply airflow generated by the supply air blower is drawn from the outside into the inside of the housing and then flows from the inside of the housing towards the room.

7. The air conditioning system according to claim 3, wherein at least one of the plurality of air conditioning devices is an air circulation type air conditioning device, and in the air circulation type air conditioning device, the supply airflow generated by the supply air blower is drawn from the room into the inside of the housing and then flows from the inside of the housing towards the room.

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