Patent Description:
Recently, a refrigeration apparatus has been required to use a refrigerant having less environmental impact to suppress global warming. Refrigerants having less environmental impact than HFC (hydrofluorocarbon) refrigerants that are widely and conventionally used include low-GWP (global warming potential) refrigerants.

However, many of the low-GWP refrigerants have flammability.

Techniques have been devised that enable detection of a refrigerant leak to address a leak of refrigerant from a refrigeration apparatus. For example, in <CIT>, a method is proposed for, if refrigerant leaks, detecting the leak by using changes in the velocity of sound propagating in air in accordance with changes in the concentration of the refrigerant in the air. Further prior art can be found in <CIT> and <CIT>.

Moreover, <CIT> discloses a refrigeration apparatus including a refrigerant circuit that has refrigerant charged therein and that performs a refrigeration cycle, the refrigeration apparatus comprising:.

However, the method for detecting a refrigerant leak by using changes in the velocity of sound has a problem such as changing the degree of incidence of a reflected sound wave on a microphone depending on the material of a reflection surface from which the sound wave is reflected. Thus, it is difficult to accurately detect a refrigerant leak.

It is also possible to consider the detection of a leak using an electric sensor that is capable of detection when the concentration of refrigerant in air becomes greater than or equal to a predetermined concentration. However, if a very slight leak that does not lead to ignition is detectable, the operation of the refrigeration apparatus may be stopped more than necessary.

In particular, the possibility that ignition occurs when refrigerant leaks does not depend only on the concentration of refrigerant in a leak space. Even if the concentration of refrigerant in the leak space becomes high, no ignition may occur.

The present disclosure has been made in view of the foregoing point, and it is an object of the present disclosure to provide a refrigeration apparatus that is capable of determining an increased possibility of ignition due to a refrigerant leak.

A refrigeration apparatus according to a first aspect is a refrigeration apparatus according to claim <NUM>, the refrigeration apparatus including a refrigerant circuit, and includes a refrigerant gas sensor and an oxygen gas sense The refrigerant circuit has refrigerant charged therein and performs a refrigeration cycle. The refrigerant gas sensor detects a refrigerant gas in a target space where at least a portion of the refrigeration apparatus is located. The oxygen gas sensor detects an oxygen gas in the target space.

The refrigeration apparatus may be arranged over two spaces. For example, the refrigeration apparatus may be configured to have an indoor unit mounted in a room, and an outdoor unit mounted outside the room. Alternatively, for example, the refrigeration apparatus may be configured such that a portion thereof directed to the inside of a room and a portion thereof directed to the outside of the room are integrated into a single unit by a single casing.

In the refrigeration apparatus, it is possible to determine the possibility of ignition due to a leak of refrigerant by using both the detection of a refrigerant gas by the refrigerant gas sensor and the detection of an oxygen gas by the oxygen gas sensor. Accordingly, the ignition possibility due to a refrigerant leak can be more accurately determined than the case where only a refrigerant gas is detected.

A refrigeration apparatus according to a second aspect is the refrigeration apparatus according to the first aspect, wherein the refrigerant charged in the refrigerant circuit is a single-component refrigerant that is one of a flammable refrigerant, a low flammable refrigerant, a mildly flammable refrigerant, and an ammonia refrigerant, or a refrigerant mixture of two or more thereof.

Examples of the flammable refrigerant include refrigerants classified in Class A3 of ASHRAE <NUM> Refrigerant Safety Classification. Examples of the low flammable refrigerant include refrigerants classified in Class A2 of ASHRAE <NUM> Refrigerant Safety Classification. Examples of the mildly flammable refrigerant include refrigerants classified in Class A2L of ASHRAE <NUM> Refrigerant Safety Classification.

In this refrigeration apparatus, when a refrigerant that has an ignition possibility when leaking is used in the refrigerant circuit, it is possible to determine the possibility of ignition.

A refrigeration apparatus according to a third aspect is the refrigeration apparatus according to the first aspect, wherein the refrigerant charged in the refrigerant circuit is R32 or a refrigerant with lower GWP than R32.

Examples of the refrigerant with lower GWP than R32 include a natural refrigerant such as R717 and, R170, R1270, R290, R600, R600a, R152a, and a refrigerant mixture of two or more thereof.

In this refrigeration apparatus, when a refrigerant with low GWP (global warming potential) is used in the refrigerant circuit, it is possible to determine the possibility of ignition.

The refrigeration apparatus according to the first aspect further includes a control unit. The control unit provides a notification indicating that an ignition possibility has occurred, or changes an operation of the refrigeration cycle in the refrigerant circuit or stops the operation of the refrigeration cycle in the refrigerant circuit, on the basis of detected information obtained from the refrigerant gas sensor and the oxygen gas sensor.

The notification indicating that an ignition possibility has occurred includes, for example, but not limited to, a notification provided by outputting a sound, a notification provided by emitting light from a lamp or blinking the lamp, a notification provided by transmitting information indicating that an ignition possibility has occurred to an external device connected via a communication network, or a combination thereof.

The change in the operation of the refrigeration cycle in the refrigerant circuit includes, for example, but not limited to, changing the operating state to interrupt the supply of refrigerant to a leak portion, and changing the operating state to reduce the amount of refrigerant that is circulated by, for example, reducing the driving frequency of the compressor.

In this refrigeration apparatus, the control unit provides a notification indicating that an ignition possibility has occurred, or changes the operation of the refrigeration cycle in the refrigerant circuit or stops the operation of the refrigeration cycle in the refrigerant circuit. Accordingly, it is possible to inform the user that an ignition possibility has occurred or to suppress a further increase of the ignition possibility.

A refrigeration apparatus according to a fourth aspect is the refrigeration apparatus according to the first aspect, further including an air temperature sensor. The air temperature sensor detects an air temperature in the target space. The control unit provides a notification indicating that an ignition possibility has occurred, or changes an operation of the refrigeration cycle in the refrigerant circuit or stops the operation of the refrigeration cycle in the refrigerant circuit, on the basis of detected information obtained from the refrigerant gas sensor, the oxygen gas sensor, and the air temperature sensor.

In this refrigeration apparatus, when providing a notification indicating that an ignition possibility has occurred, or changing the operation of the refrigeration cycle in the refrigerant circuit or stopping the operation of the refrigeration cycle in the refrigerant circuit, the control unit performs determination on the basis of detected information obtained not only from the refrigerant gas sensor and the oxygen gas sensor but also from the air temperature sensor. Accordingly, the control unit can perform determination by taking into account the effect of the air temperature in the target space on the ignition possibility (such as taking into account that the higher the air temperature is, the higher the ignition possibility becomes).

A refrigeration apparatus according to a fifth aspect is the refrigeration apparatus according to the fourth aspect, wherein the control unit performs first determination based on the detected information obtained from the refrigerant gas sensor and the oxygen gas sensor. The control unit performs second determination based on the detected information obtained from the refrigerant gas sensor, the oxygen gas sensor, and the air temperature sensor. The control unit provides the notification or changes or stops the operation in a different way in accordance with a result of the first determination and a result of the second determination.

In this refrigeration apparatus, the control unit performs two stages of determination, namely, first determination based on the detected information obtained from the refrigerant gas sensor and the oxygen gas sensor, and second determination based on the detected information obtained from the refrigerant gas sensor, the oxygen gas sensor, and the air temperature sensor, and provides the notification or changes or stops the operation in a different way in accordance with each stage. Accordingly, it is possible to provide a notification or change or stop the operation in a different way in accordance with the level of risk about the ignition possibility.

The notification provided in a different way includes, for example, but not limited to, a notification provided by outputting a sound with a higher volume for the second stage than for the first stage, and a notification provided by emitting light from a lamp or blinking the lamp with a larger amount of emission of light or a higher blinking speed for the second stage than for the first stage.

The change in the operation or stop of the operation includes, for example, but not limited to, continuing the operation in an operating state in which the amount of leak is reduced for the first stage, whereas completely stopping the operation for the second stage.

A refrigeration apparatus according to a sixth aspect is the refrigeration apparatus according to the first aspect, further including an air humidity sensor. The air humidity sensor detects an air humidity in the target space. The control unit provides a notification indicating that an ignition possibility has occurred, or changes an operation of the refrigeration cycle in the refrigerant circuit or stops the operation of the refrigeration cycle in the refrigerant circuit, on the basis of detected information obtained from the refrigerant gas sensor, the oxygen gas sensor, and the air humidity sensor.

In this refrigeration apparatus, when providing a notification indicating that an ignition possibility has occurred, or changing the operation of the refrigeration cycle in the refrigerant circuit or stopping the operation of the refrigeration cycle in the refrigerant circuit, the control unit performs determination on the basis of detected information obtained not only from the refrigerant gas sensor and the oxygen gas sensor but also from the air humidity sensor. Accordingly, the control unit can perform determination by taking into account the effect of the air humidity in the target space on the ignition possibility (such as taking into account that the higher the air humidity is, the higher the ignition possibility becomes).

A refrigeration apparatus according to an seventh aspect is the refrigeration apparatus according to the sixth aspect, wherein the control unit performs first determination based on the detected information obtained from the refrigerant gas sensor and the oxygen gas sensor. The control unit performs second determination based on the detected information obtained from the refrigerant gas sensor, the oxygen gas sensor, and the air humidity sensor. The control unit provides the notification or changes or stops the operation in a different way in accordance with a result of the first determination and a result of the second determination.

In this refrigeration apparatus, the control unit performs two stages of determination, namely, first determination based on the detected information obtained from the refrigerant gas sensor and the oxygen gas sensor, and second determination based on the detected information obtained from the refrigerant gas sensor, the oxygen gas sensor, and the air humidity sensor, and provides the notification or changes or stops the operation in a different way in accordance with each stage. Accordingly, it is possible to provide a notification or change or stop the operation in a different way in accordance with the level of risk about the ignition possibility.

A refrigeration apparatus according to an eighth aspect is the refrigeration apparatus according to the first aspect, further including a fan. The fan generates an air flow in the target space. The control unit causes the fan to forcibly blow air on the basis of the detected information obtained from the refrigerant gas sensor and the oxygen gas sensor.

In this refrigeration apparatus, even if the ignition possibility is increased, the fan is caused to forcibly blow air, thereby allowing the leaking refrigerant to spread out and enabling a reduction in the ignition possibility.

A refrigeration apparatus according to a ninth aspect is the refrigeration apparatus according to the first aspect, further including a human detecting sensor. The human detecting sensor detects a moving object in the target space. The control unit provides a notification indicating that an ignition possibility has occurred, or changes an operation of the refrigeration cycle in the refrigerant circuit or stops the operation of the refrigeration cycle in the refrigerant circuit, on the basis of detected information obtained from the refrigerant gas sensor, the oxygen gas sensor, and the human detecting sensor.

The moving object includes, for example, but not limited to, an animal and a person.

The human detecting sensor includes, for example, but not limited to, an infrared sensor, an ultrasonic sensor, a visible light sensor, and a camera.

In this refrigeration apparatus, when providing a notification indicating that an ignition possibility has occurred, or changing the operation of the refrigeration cycle in the refrigerant circuit or stopping the operation of the refrigeration cycle in the refrigerant circuit, the control unit performs determination on the basis of detected information obtained not only from the refrigerant gas sensor and the oxygen gas sensor but also from the human detecting sensor. Accordingly, the control unit can perform determination by taking into account the detection content of the human detecting sensor for a moving object in the target space. Thus, for example, when no moving object is present in the target space, no notification can be provided, or a notification, when provided, can be provided by, for example, using a sound with a lower volume than in the case where a moving object is present in the target space. In addition, it is possible to take countermeasures such as continuing the operation when no moving object is present in the target space, and stopping the operation when a moving object is present in the target space.

A refrigeration apparatus according to a tenth aspect is the refrigeration apparatus according to the first aspect, further including a refrigerant pressure sensor. The refrigerant pressure sensor detects a pressure of the refrigerant in the refrigerant circuit. The control unit provides a notification indicating that an ignition possibility has occurred, or changes an operation of the refrigeration cycle in the refrigerant circuit or stops the operation of the refrigeration cycle in the refrigerant circuit, on the basis of detected information obtained from the refrigerant gas sensor, the oxygen gas sensor, and the refrigerant pressure sensor.

In this refrigeration apparatus, when providing a notification indicating that an ignition possibility has occurred, or changing the operation of the refrigeration cycle in the refrigerant circuit or stopping the operation of the refrigeration cycle in the refrigerant circuit, the control unit performs determination on the basis of detected information obtained not only from the refrigerant gas sensor and the oxygen gas sensor but also from the refrigerant pressure sensor. Accordingly, it is possible to enhance the reliability with which the control unit determines the ignition possibility.

For example, when the pressure detected by the refrigerant pressure sensor does not satisfy a predetermined pressure condition and is less than the predetermined pressure condition, it can be determined that a leak is likely to have occurred. It is therefore possible to enhance the reliability of performing determination for providing a notification, or changing or stopping the operation.

A refrigeration apparatus according to an eleventh aspect is the refrigeration apparatus according to the first aspect, further including an ultrasonic sensor. The ultrasonic sensor detects, while outputting an ultrasound wave to the target space, a reflected wave of the ultrasound wave from the target space. The control unit provides a notification indicating that an ignition possibility has occurred, or changes an operation of the refrigeration cycle in the refrigerant circuit or stops the operation of the refrigeration cycle in the refrigerant circuit, on the basis of detected information obtained from the refrigerant gas sensor, the oxygen gas sensor, and the ultrasonic sensor.

In this refrigeration apparatus, when providing a notification indicating that an ignition possibility has occurred, or changing the operation of the refrigeration cycle in the refrigerant circuit or stopping the operation of the refrigeration cycle in the refrigerant circuit, the control unit performs determination on the basis of detected information obtained not only from the refrigerant gas sensor and the oxygen gas sensor but also from the ultrasonic sensor. Accordingly, it is possible to further enhance the reliability with which the control unit determines the ignition possibility.

For example, when the reflected wave detected by the ultrasonic sensor satisfies a predetermined sound wave leak condition, it can be determined that a leak is likely to have occurred. It is therefore possible to enhance the reliability of performing determination for providing a notification, or changing or stopping the operation.

The following describes an air conditioner <NUM>, which is a refrigeration apparatus according to an embodiment of the invention, with reference to the drawings. It should be noted that the following embodiment is a specific example and is not intended to limit the scope of the disclosure, but can be modified, as appropriate, without departing from the scope of the disclosure.

<FIG> is a schematic configuration diagram of the air conditioner <NUM> according to an embodiment. The air conditioner <NUM> is an apparatus that performs air conditioning of a target space by performing a vapor-compression refrigeration cycle.

The air conditioner <NUM> mainly includes an outdoor unit <NUM>, an indoor unit <NUM>, a liquid-refrigerant connection pipe <NUM> and a gas-refrigerant connection pipe <NUM> that connect the outdoor unit <NUM> and the indoor unit <NUM>, a plurality of remote controls 50a, each of which serves as an input device and an output device, and a controller <NUM> that controls the operation of the air conditioner <NUM>.

In the air conditioner <NUM>, a refrigeration cycle is performed such that refrigerant charged in a refrigerant circuit <NUM> is compressed, cooled or condensed, decompressed, heated or evaporated, and then compressed again. In this embodiment, the refrigerant circuit <NUM> is filled with R32 as a refrigerant for a vapor-compression refrigeration cycle.

The outdoor unit <NUM> is connected to the indoor unit <NUM> through the liquid-refrigerant connection pipe <NUM> and the gas-refrigerant connection pipe <NUM> and forms a portion of the refrigerant circuit <NUM>. The outdoor unit <NUM> mainly includes a compressor <NUM>, a four-way switching valve <NUM>, an outdoor heat exchanger <NUM>, an outdoor expansion valve <NUM>, an outdoor fan <NUM>, a liquid-side shutoff valve <NUM>, and a gas-side shutoff valve <NUM>.

The outdoor unit <NUM> further includes pipes constituting the refrigerant circuit <NUM>, namely, a discharge pipe <NUM>, a suction pipe <NUM>, an outdoor gas-side pipe <NUM>, and an outdoor liquid-side pipe <NUM>. The discharge pipe <NUM> connects the discharge side of the compressor <NUM> and a first connection port of the four-way switching valve <NUM>. The suction pipe <NUM> connects the suction side of the compressor <NUM> and a second connection port of the four-way switching valve <NUM>. The outdoor gas-side pipe <NUM> connects a third connection port of the four-way switching valve <NUM> and the gas-side shutoff valve <NUM>. The outdoor liquid-side pipe <NUM> extends from a fourth connection port of the four-way switching valve <NUM> to the liquid-side shutoff valve <NUM> through the outdoor heat exchanger <NUM> and the outdoor expansion valve <NUM>.

The compressor <NUM> is a device that compresses a low-pressure refrigerant in the refrigeration cycle to a high-pressure refrigerant. The compressor <NUM> is implemented here as a hermetically sealed compressor in which a positive displacement compression element (not illustrated), such as a rotary or scroll compression element, is driven to rotate by a compressor motor M21. The compressor motor M21 is used to change volume and has an operating frequency that can be controlled by an inverter.

The connection state of the four-way switching valve <NUM> can be switched to switch the four-way switching valve <NUM> between a cooling-operation connection state in which the suction side of the compressor <NUM> and the gas-side shutoff valve <NUM> are connected while the discharge side of the compressor <NUM> and the outdoor heat exchanger <NUM> are connected and a heating-operation connection state in which the suction side of the compressor <NUM> and the outdoor heat exchanger <NUM> are connected while the discharge side of the compressor <NUM> and the gas-side shutoff valve <NUM> are connected.

The outdoor heat exchanger <NUM> is a heat exchanger that functions as a radiator for a high-pressure refrigerant in the refrigeration cycle during a cooling operation and that functions as an evaporator for a low-pressure refrigerant in the refrigeration cycle during a heating operation.

The outdoor fan <NUM> generates an air flow for sucking outdoor air into the outdoor unit <NUM>, allowing the air to exchange heat with the refrigerant in the outdoor heat exchanger <NUM>, and then discharging the air to the outside. The outdoor fan <NUM> is driven to rotate by an outdoor fan motor M25.

The outdoor expansion valve <NUM> is an electric expansion valve whose valve opening degree is controllable, and is disposed midway in the outdoor liquid-side pipe <NUM> between the outdoor heat exchanger <NUM> and the liquid-side shutoff valve <NUM>.

The liquid-side shutoff valve <NUM> is a manual valve that is arranged in a connecting portion between the outdoor liquid-side pipe <NUM> and the liquid-refrigerant connection pipe <NUM>.

The gas-side shutoff valve <NUM> is a manual valve that is arranged in a connecting portion between the outdoor gas-side pipe <NUM> and the gas-refrigerant connection pipe <NUM>.

The outdoor unit <NUM> has various sensors arranged therein.

Specifically, the outdoor unit <NUM> has arranged, near the compressor <NUM>, a suction temperature sensor <NUM> to detect a suction temperature that is the temperature of refrigerant on the suction side of the compressor <NUM>, a suction pressure sensor <NUM> to detect a suction pressure that is the pressure of refrigerant on the suction side of the compressor <NUM>, and a discharge pressure sensor <NUM> to detect a discharge pressure that is the pressure of refrigerant on the discharge side of the compressor <NUM>.

The outdoor heat exchanger <NUM> is also provided with an outdoor heat-exchange temperature sensor <NUM> to detect the temperature of refrigerant flowing through the outdoor heat exchanger <NUM>.

Further, an outside air temperature sensor <NUM> is arranged near the outdoor heat exchanger <NUM> or the outdoor fan <NUM> to detect the temperature of outdoor air that is sucked into the outdoor unit <NUM>.

The outdoor unit <NUM> includes an outdoor-unit control unit <NUM> that controls the operation of components of the outdoor unit <NUM>. The outdoor-unit control unit <NUM> has a microcomputer including a CPU, a memory, and so on. The outdoor-unit control unit <NUM> is connected to an indoor-unit control unit <NUM> of indoor unit <NUM> via a communication line, and transmits and receives control signals and the like. Further, the outdoor-unit control unit <NUM> is electrically connected to the suction temperature sensor <NUM>, the suction pressure sensor <NUM>, the discharge pressure sensor <NUM>, the outdoor heat-exchange temperature sensor <NUM>, and the outside air temperature sensor <NUM>, and receives a signal from each of the sensors.

The indoor unit <NUM> is mounted on the wall surface, the ceiling, or the like of a room that is the target space. The indoor unit <NUM> is connected to the outdoor unit <NUM> through the liquid-refrigerant connection pipe <NUM> and the gas-refrigerant connection pipe <NUM> and forms a portion of the refrigerant circuit <NUM>.

The indoor unit <NUM> includes an indoor expansion valve <NUM>, an indoor heat exchanger <NUM>, and an indoor fan <NUM>.

The indoor unit <NUM> further includes an indoor liquid refrigerant pipe <NUM> that connects the liquid-side end of the indoor heat exchanger <NUM> and the liquid-refrigerant connection pipe <NUM>, and an indoor gas refrigerant pipe <NUM> that connects the gas-side end of the indoor heat exchanger <NUM> and the gas-refrigerant connection pipe <NUM>.

The indoor expansion valve <NUM> is an electric expansion valve whose valve opening degree is controllable, and is disposed midway in the indoor liquid refrigerant pipe <NUM>.

The indoor heat exchanger <NUM> is a heat exchanger that functions as an evaporator for a low-pressure refrigerant in the refrigeration cycle during a cooling operation and that functions as a radiator for a high-pressure refrigerant in the refrigeration cycle during a heating operation.

The indoor fan <NUM> generates an air flow for sucking indoor air into the indoor unit <NUM>, allowing the air to exchange heat with the refrigerant in the indoor heat exchanger <NUM>, and then discharging the air to the outside. The indoor fan <NUM> is driven to rotate by an indoor fan motor M53.

The indoor unit <NUM> has various sensors arranged therein.

Specifically, the indoor unit <NUM> has arranged therein a refrigerant gas sensor <NUM> (e.g., a sensor that electrically reacts differently in accordance with the refrigerant gas concentration) to detect the concentration of the refrigerant gas charged in the refrigerant circuit <NUM>, an oxygen gas sensor <NUM> to detect the oxygen concentration, an air temperature sensor <NUM> to detect the air temperature in a space where the indoor unit <NUM> is installed, an infrared sensor <NUM> to detect a moving object in the space where the indoor unit <NUM> is installed, and an indoor heat-exchange temperature sensor <NUM> to detect the temperature of refrigerant flowing through the indoor heat exchanger <NUM>.

Further, the indoor unit <NUM> includes the indoor-unit control unit <NUM>, which controls the operation of components of the indoor unit <NUM>. The indoor-unit control unit <NUM> has a microcomputer including a CPU, a memory, and so on. The indoor-unit control unit <NUM> is connected to the outdoor-unit control unit <NUM> via a communication line, and transmits and receives control signals and the like.

The indoor-unit control unit <NUM> is electrically connected to the refrigerant gas sensor <NUM>, the oxygen gas sensor <NUM>, the air temperature sensor <NUM>, the infrared sensor <NUM>, and the indoor heat-exchange temperature sensor <NUM>, and receives a signal from each of the sensors.

The remote control 50a is an input device used by the user of the indoor unit <NUM> to input various instructions to switch the operating state of the air conditioner <NUM>. The remote control 50a also functions as an output device for informing the user of the operating state of the air conditioner <NUM> or providing a predetermined notification. The remote control 50a and the indoor-unit control unit <NUM> are connected via a communication line and transmit and receive signals to and from each other. The remote control 50a has a built-in speaker.

In the air conditioner <NUM>, the outdoor-unit control unit <NUM> and the indoor-unit control unit <NUM>, which are connected via a communication line, form the controller <NUM> that controls the operation of the air conditioner <NUM>.

<FIG> is a block diagram schematically illustrating the general configuration of the controller <NUM> and components connected to the controller <NUM>.

The controller <NUM> has a plurality of control modes, and controls the operation of the air conditioner <NUM> in accordance with the control modes. For example, the controller <NUM> has, as the control modes, a normal operation mode, which is executed under normal conditions, and a refrigerant leak control mode, which is executed when a refrigerant leak occurs.

The controller <NUM> is electrically connected to the actuators included in the outdoor unit <NUM> (specifically, the compressor <NUM> (the compressor motor M21), the outdoor expansion valve <NUM>, and the outdoor fan <NUM> (the outdoor fan motor M25)) and the various sensors included in the outdoor unit <NUM> (such as the suction temperature sensor <NUM>, the suction pressure sensor <NUM>, the discharge pressure sensor <NUM>, the outdoor heat-exchange temperature sensor <NUM>, and the outside air temperature sensor <NUM>). The controller <NUM> is also electrically connected to the actuators included in the indoor unit <NUM> (specifically, the indoor fan <NUM> (the indoor fan motor M53) and the indoor expansion valve <NUM>). Further, the controller <NUM> is electrically connected to the refrigerant gas sensor <NUM>, the oxygen gas sensor <NUM>, the air temperature sensor <NUM>, the infrared sensor <NUM>, the indoor heat-exchange temperature sensor <NUM>, and the remote control 50a.

The controller <NUM> mainly includes a storage unit <NUM>, a communication unit <NUM>, a mode control unit <NUM>, an actuator control unit <NUM>, and an output control unit <NUM>. These components in the controller <NUM> are implemented by the integrated functioning of the components included in the outdoor-unit control unit <NUM> and/or the indoor-unit control unit <NUM>.

The storage unit <NUM> is constituted by, for example, a ROM, a RAM, a flash memory, and so on and includes a volatile storage area and a non-volatile storage area. The storage unit <NUM> stores a control program that defines processes performed by the components of the controller <NUM>. The storage unit <NUM> further stores predetermined information (such as values detected by sensors and commands input to the remote control 50a) in predetermined storage areas, as appropriate, by using the components of the controller <NUM>.

The communication unit <NUM> is a function unit that serves as a communication interface for transmitting and receiving signals to and from devices connected to the controller <NUM>. The communication unit <NUM> transmits a predetermined signal to a designated actuator upon receipt of a request from the actuator control unit <NUM>. Further, upon receipt of a signal output from each of the sensors <NUM> to <NUM>, <NUM> to <NUM>, <NUM>, and <NUM> and the remote control 50a, the communication unit <NUM> stores the signal in a predetermined storage area of the storage unit <NUM>.

The mode control unit <NUM> is a function unit that performs processing such as switching between the control modes. When a predetermined refrigerant leak condition is not satisfied for indoor unit <NUM>, the mode control unit <NUM> sets the control mode to the normal operation mode.

On the other hand, when the predetermined refrigerant leak condition is satisfied for the indoor unit <NUM>, the mode control unit <NUM> switches the control mode to the refrigerant leak control mode.

The actuator control unit <NUM> controls the operation of the actuators (such as the compressor <NUM>) included in the air conditioner <NUM> in accordance with the control program.

For example, in the normal operation mode, the actuator control unit <NUM> controls the number of revolutions of the compressor <NUM>, the numbers of revolutions of the outdoor fan <NUM> and the indoor fan <NUM>, the valve opening degree of the outdoor expansion valve <NUM>, the valve opening degree of the indoor expansion valve <NUM>, and the like in real time in accordance with a set temperature, values detected by various sensors, and so on.

In the refrigerant leak control mode, the actuator control unit <NUM> controls the operation of the actuators so that a predetermined operation can be performed. Specifically, when refrigerant leaks, the actuator control unit <NUM> interrupts the supply of refrigerant to the indoor unit <NUM>.

The output control unit <NUM> is a function unit that controls the operation of the remote control 50a, which serves as a display device.

The output control unit <NUM> causes the remote control 50a to output predetermined information so as to present information related to the operating state or conditions to an administrator.

For example, during the execution of the cooling operation mode in the normal operation mode, the output control unit <NUM> causes the remote control 50a to display various kinds of information such as a set temperature.

In the refrigerant leak control mode, the output control unit <NUM> causes a display of the remote control 50a to display information indicating the occurrence of a refrigerant leak. Further, the output control unit <NUM> provides an audible notification indicating the occurrence of a refrigerant leak by using the built-in speaker of the remote control 50a. The output control unit <NUM> further causes the remote control 50a to display information to promote notification to a service engineer.

The following describes the normal operation mode.

The normal operation mode includes a cooling operation mode and a heating operation mode.

The controller <NUM> determines and performs the cooling operation mode or the heating operation mode in accordance with an instruction received from the remote control 50a or the like.

In the air conditioner <NUM>, in the cooling operation mode, the connection state of the four-way switching valve <NUM> is set to a cooling-operation connection state in which the suction side of the compressor <NUM> and the gas-side shutoff valve <NUM> are connected while the discharge side of the compressor <NUM> and the outdoor heat exchanger <NUM> are connected. The refrigerant with which the refrigerant circuit <NUM> is filled is mainly circulated in the order of the compressor <NUM>, the outdoor heat exchanger <NUM>, the outdoor expansion valve <NUM>, the indoor expansion valve <NUM>, and the indoor heat exchanger <NUM>.

More specifically, when the cooling operation mode is started, in the refrigerant circuit <NUM>, the refrigerant is sucked into the compressor <NUM>, compressed, and then discharged. A low pressure in the refrigeration cycle corresponds to a suction pressure detected by the suction pressure sensor <NUM>, and a high pressure in the refrigeration cycle corresponds to a discharge pressure detected by the discharge pressure sensor <NUM>.

In the compressor <NUM>, capacity control is performed in accordance with cooling load required for the indoor unit <NUM>. Specifically, a target value of the suction pressure is set in accordance with the cooling load required for the indoor unit <NUM>, and the operating frequency of the compressor <NUM> is controlled such that the suction pressure becomes equal to the target value.

The gas refrigerant discharged from the compressor <NUM> travels through the discharge pipe <NUM> and the four-way switching valve <NUM>, and flows into the gas-side end of the outdoor heat exchanger <NUM>.

The gas refrigerant that has flowed into the gas-side end of the outdoor heat exchanger <NUM> releases heat and condenses into a liquid refrigerant in the outdoor heat exchanger <NUM> by exchanging heat with outdoor-side air supplied by the outdoor fan <NUM>. The liquid refrigerant flows out of the liquid-side end of the outdoor heat exchanger <NUM>.

The liquid refrigerant that has flowed out of the liquid-side end of the outdoor heat exchanger <NUM> travels through the outdoor liquid-side pipe <NUM>, the outdoor expansion valve <NUM>, the liquid-side shutoff valve <NUM>, and the liquid-refrigerant connection pipe <NUM>, and flows into the indoor unit <NUM>. In the cooling operation mode, the outdoor expansion valve <NUM> is controlled to be fully opened.

The refrigerant that has flowed into the indoor unit <NUM> travels through a portion of the indoor liquid refrigerant pipe <NUM>, and flows into the indoor expansion valve <NUM>. The refrigerant that has flowed into the indoor expansion valve <NUM> is decompressed by the indoor expansion valve <NUM> until the refrigerant becomes a low-pressure refrigerant in the refrigeration cycle, and then flows into the liquid-side end of the indoor heat exchanger <NUM>. In the cooling operation mode, the valve opening degree of the indoor expansion valve <NUM> is controlled such that the degree of superheating of refrigerant sucked into the compressor <NUM> becomes equal to a predetermined degree of superheating. The degree of superheating of refrigerant sucked into the compressor <NUM> is calculated by the controller <NUM> by using the temperature detected by the suction temperature sensor <NUM> and the pressure detected by the suction pressure sensor <NUM>. The refrigerant that has flowed into the liquid-side end of the indoor heat exchanger <NUM> evaporates into a gas refrigerant in the indoor heat exchanger <NUM> by exchanging heat with indoor air supplied by the indoor fan <NUM>. The gas refrigerant flows out of the gas-side end of the indoor heat exchanger <NUM>. The gas refrigerant that has flowed out of the gas-side end of the indoor heat exchanger <NUM> flows to the gas-refrigerant connection pipe <NUM> through the indoor gas refrigerant pipe <NUM>.

In this way, the refrigerant flowing through the gas-refrigerant connection pipe <NUM> travels through the gas-side shutoff valve <NUM>, the outdoor gas-side pipe <NUM>, the four-way switching valve <NUM>, and the suction pipe <NUM>, and is again sucked into the compressor <NUM>.

In the air conditioner <NUM>, in the heating operation mode, the connection state of the four-way switching valve <NUM> is set to a heating-operation connection state in which the suction side of the compressor <NUM> and the outdoor heat exchanger <NUM> are connected while the discharge side of the compressor <NUM> and the gas-side shutoff valve <NUM> are connected. The refrigerant with which the refrigerant circuit <NUM> is filled is mainly circulated in the order of the compressor <NUM>, the indoor heat exchanger <NUM>, the indoor expansion valve <NUM>, the outdoor expansion valve <NUM>, and the outdoor heat exchanger <NUM>.

More specifically, when the heating operation mode is started, in the refrigerant circuit <NUM>, the refrigerant is sucked into the compressor <NUM>, compressed, and then discharged. A low pressure in the refrigeration cycle corresponds to a suction pressure detected by the suction pressure sensor <NUM>, and a high pressure in the refrigeration cycle corresponds to a discharge pressure detected by the discharge pressure sensor <NUM>.

In the compressor <NUM>, capacity control is performed in accordance with the heating load required for the indoor unit <NUM>. Specifically, a target value of the discharge pressure is set in accordance with the heating load required for the indoor unit <NUM>, and the operating frequency of the compressor <NUM> is controlled such that the discharge pressure becomes equal to the target value.

The gas refrigerant discharged from the compressor <NUM> flows through the discharge pipe <NUM>, the four-way switching valve <NUM>, the outdoor gas-side pipe <NUM>, and the gas-refrigerant connection pipe <NUM>, and then flows into the indoor unit <NUM> through the indoor gas refrigerant pipe <NUM>.

The refrigerant that has flowed into the indoor unit <NUM> travels through the indoor gas refrigerant pipe <NUM>, and flows into the gas-side end of the indoor heat exchanger <NUM>. The refrigerant that has flowed into the gas-side end of the indoor heat exchanger <NUM> releases heat and condenses into a liquid refrigerant in the indoor heat exchanger <NUM> by exchanging heat with indoor air supplied by the indoor fan <NUM>. The liquid refrigerant flows out of the liquid-side end of the indoor heat exchanger <NUM>. The refrigerant that has flowed out of the liquid-side end of the indoor heat exchanger <NUM> flows to the liquid-refrigerant connection pipe <NUM> through the indoor liquid refrigerant pipe <NUM> and the indoor expansion valve <NUM>. In the heating operation mode, the valve opening degree of the indoor expansion valve <NUM> is controlled to be fully opened.

In this way, the refrigerant flowing through the liquid-refrigerant connection pipe <NUM> flows into the outdoor expansion valve <NUM> through the liquid-side shutoff valve <NUM> and the outdoor liquid-side pipe <NUM>.

The refrigerant that has flowed into the outdoor expansion valve <NUM> is decompressed until the refrigerant becomes a low-pressure refrigerant in the refrigeration cycle, and then flows into the liquid-side end of the outdoor heat exchanger <NUM>. In the heating operation mode, the valve opening degree of the outdoor expansion valve <NUM> is controlled such that the degree of superheating of refrigerant sucked into the compressor <NUM> becomes equal to a predetermined degree of superheating.

The refrigerant that has flowed into the liquid-side end of the outdoor heat exchanger <NUM> evaporates into a gas refrigerant in the outdoor heat exchanger <NUM> by exchanging heat with outdoor air supplied by the outdoor fan <NUM>. The gas refrigerant flows out of the gas-side end of the outdoor heat exchanger <NUM>.

The refrigerant that has flowed out of the gas-side end of the outdoor heat exchanger <NUM> travels through the four-way switching valve <NUM> and the suction pipe <NUM>, and is again sucked into the compressor <NUM>.

The following describes an example process flow for the refrigerant leak control mode, which is executed by the controller <NUM> when a refrigerant leak occurs in the normal operation mode with reference to a flowchart illustrated in <FIG>.

In step S <NUM>, when the normal operation mode of the cooling operation mode or heating operation mode is being executed, the controller <NUM> determines whether the refrigerant concentration detected by the refrigerant gas sensor <NUM> is greater than or equal to a predetermined refrigerant concentration. The predetermined refrigerant concentration is determined in advance in accordance with the type of the refrigerant charged in the refrigerant circuit <NUM> (in this embodiment, R32) and is stored in the storage unit <NUM>. If the controller <NUM> determines that the refrigerant concentration detected by the refrigerant gas sensor <NUM> is greater than or equal to the predetermined refrigerant concentration, the process proceeds to step S11. On the other hand, if the refrigerant concentration detected by the refrigerant gas sensor <NUM> is less than the predetermined refrigerant concentration, the normal operation mode remains continuously active and step S10 is repeatedly performed.

In step S11, the controller <NUM> starts the refrigerant leak control mode and causes the output control unit <NUM> to display, on the display of the remote control 50a, information indicating a leak of refrigerant as text information. Further, the controller <NUM> causes the output control unit <NUM> to provide a notification indicating the leak of refrigerant as audio information from the speaker of the remote control 50a.

In step S12, the controller <NUM> determines whether the oxygen concentration detected by the oxygen gas sensor <NUM> is greater than or equal to a predetermined oxygen concentration. The predetermined oxygen concentration is determined in advance in accordance with the type of the refrigerant charged in the refrigerant circuit <NUM> (in this embodiment, R32) and is stored in the storage unit <NUM>. If the controller <NUM> determines that the oxygen concentration detected by the oxygen gas sensor <NUM> is greater than or equal to the predetermined oxygen concentration, the process proceeds to step S13. On the other hand, if the oxygen concentration detected by the oxygen gas sensor <NUM> is less than the predetermined oxygen concentration, step S12 is repeatedly performed.

In step S13, the controller <NUM> causes the output control unit <NUM> to display, on the display of the remote control 50a, information indicating that an ignition possibility has occurred due to the leak of refrigerant as text information. Further, the controller <NUM> causes the output control unit <NUM> to provide a notification indicating that an ignition possibility has occurred due to the leak of refrigerant as audio information from the speaker of the remote control 50a (notification with a greater sound than that in step S11).

In step S14, the controller <NUM> controls the indoor fan <NUM> to forcibly operate with a maximum number of revolutions. This allows the refrigerant that has leaked to be stirred and can suppress a local increase in concentration.

In step S15, the controller <NUM> determines whether the infrared sensor <NUM> has detected a moving object such as a person or an animal in the room. If the controller <NUM> determines that the infrared sensor <NUM> has detected an object, the process proceeds to step S16. On the other hand, if it is determined that no object is detected by the infrared sensor <NUM>, the process proceeds to step S <NUM>.

In step S16, the controller <NUM> determines whether the temperature of air in the room, which is detected by the air temperature sensor <NUM>, is greater than or equal to a predetermined air temperature. The predetermined air temperature is determined in advance in accordance with the type of the refrigerant charged in the refrigerant circuit <NUM> (in this embodiment, R32) and is stored in the storage unit <NUM>. In most refrigerants, including R32, the ignition possibility increases as the air temperature increases. If the controller <NUM> determines that the temperature of air in the room, which is detected by the air temperature sensor <NUM>, is greater than or equal to the predetermined air temperature, the process proceeds to step S17. On the other hand, if it is determined that the temperature is not greater than or equal to the predetermined air temperature, the process proceeds to step S18.

In step S17, the controller <NUM> causes the output control unit <NUM> to display, on the display of the remote control 50a, information indicating that the ignition possibility becomes high due to the leak of refrigerant as text information. Further, the controller <NUM> causes the output control unit <NUM> to provide a notification indicating that the ignition possibility becomes high due to the leak of refrigerant as audio information from the speaker of the remote control 50a (notification with a greater sound than that in step S13).

In step S18, the controller <NUM> performs a pump-down operation. In the pump-down operation, while the connection state of the four-way switching valve <NUM> is set to the connection state in the cooling operation mode, the outdoor expansion valve <NUM> is closed, the compressor <NUM> is driven, the outdoor fan <NUM> is driven, and the outdoor heat exchanger <NUM> is caused to function as a condenser for refrigerant. Accordingly, within the refrigerant circuit <NUM>, refrigerant present on the indoor unit <NUM> side is collected before the refrigerant reaches the outdoor expansion valve <NUM> from the discharge side of the compressor <NUM> of the outdoor unit <NUM> through the outdoor heat exchanger <NUM>, thereby suppressing a further leak of refrigerant from a leak portion of the indoor unit <NUM>. In a state where the cooling operation mode is executed during a leak of refrigerant, the pump-down operation is performed, with the connection state of the four-way switching valve <NUM> remaining unchanged. In a state where the heating operation mode is executed during a leak of refrigerant, in contrast, the pump-down operation is performed after the connection state of the four-way switching valve <NUM> is switched to that in the cooling operation mode. The pump-down operation is finished when the pressure detected by the suction pressure sensor <NUM> becomes less than or equal to a predetermined termination pressure. The driving of the compressor <NUM> is stopped, and the operation of the air conditioner <NUM> is stopped.

(<NUM>-<NUM>)
In the air conditioner <NUM> according to this embodiment, if refrigerant that can be ignited leaks from the refrigerant circuit <NUM>, in addition to the refrigerant gas sensor <NUM> merely detecting the leaking refrigerant and providing a notification indicating that refrigerant has leaked, the oxygen gas sensor <NUM> is used to detect an oxygen gas. When it is determined that the refrigerant concentration of the refrigerant that has leaked is greater than or equal to a predetermined refrigerant concentration and that the oxygen gas concentration is greater than or equal to a predetermined oxygen concentration, a notification is provided indicating that an ignition possibility has occurred.

Accordingly, the concentrations of both a refrigerant gas and an oxygen gas are detected. This enables more accurate determination of an ignition possibility than the case where only a refrigerant gas that has leaked is detected.

For example, when the indoor unit <NUM> of the air conditioner <NUM> is used in a low-oxygen-concentration environment such as in a specific factory, a slight leak of refrigerant may not lead directly to the occurrence of an ignition possibility. In this case, even if refrigerant leaks, it is possible to determine that the ignition possibility is low.

Even when no ignition possibility has occurred, if refrigerant leaks and its concentration becomes greater than or equal to a predetermined refrigerant concentration, it is possible to notify the user or the like that a refrigerant leak has occurred.

(<NUM>-<NUM>)
In the air conditioner <NUM> according to this embodiment, if refrigerant has leaked in the indoor unit <NUM> and an ignition possibility has occurred, the pump-down operation is performed to collect the refrigerant in the outdoor unit <NUM>. This can suppress a further leak of refrigerant from a leak portion of the indoor unit <NUM>. This can also suppress a further increase of the ignition possibility.

(<NUM>-<NUM>)
In the air conditioner <NUM> according to this embodiment, in addition to the detection of the refrigerant concentration by the refrigerant gas sensor <NUM> and the detection of the oxygen concentration by the oxygen gas sensor <NUM>, a moving object is also detected by using the infrared sensor <NUM>. When the infrared sensor <NUM> detects the presence of a moving object in the room, it is determined whether the ignition possibility is high by using the air temperature sensor <NUM>, and the moving object can be notified of a high ignition possibility. If no moving object is present in the target space, such as when the infrared sensor <NUM> detects no object, a notification by sound with a high volume is not provided. This can suppress the occurrence of a loud sound more than necessary.

In addition, the determination of whether the ignition possibility is high can be based on air temperature or air humidity at which ignition is likely to occur in accordance with the type of the refrigerant charged in the refrigerant circuit <NUM>. Thus, whether the ignition possibility is high can be more accurately determined.

(<NUM>-<NUM>)
In the air conditioner <NUM> according to this embodiment, when it is determined that an ignition possibility has occurred, the indoor fan <NUM> is forcibly driven with a maximum number of revolutions. This can suppress the occurrence of a local increase in refrigerant concentration within the room, and ignition can be less likely to occur.

The embodiment described above can be modified as appropriate, as given in the following modifications. Each of the modifications may be used in combination with any other modification so long as consistency is maintained.

In the embodiment described above, a case has been described as an example in which the refrigerant charged in the refrigerant circuit <NUM> is R32.

The refrigerant to be charged in the refrigerant circuit <NUM> is not limited to this, and examples of the refrigerant other than R32 may include flammable refrigerants classified in Class A3 of ASHRAE <NUM> Refrigerant Safety Classification, low flammable refrigerants classified in Class A2 of ASHRAE <NUM> Refrigerant Safety Classification, and mildly flammable refrigerants classified in Class A2L of ASHRAE <NUM> Refrigerant Safety Classification. These refrigerants can also be ignited when leaking, and thus effects similar to those of the embodiment described above can be achieved.

Other examples of the refrigerant to be charged in the refrigerant circuit <NUM>, other than R32, may include refrigerants with lower GWP than R32 (a natural refrigerant such as R717 and, R170, R1270, R290, R600, R600a, R152a, and a refrigerant mixture thereof). Even when such a refrigerant as having a low GWP value is used, a leak can be appropriately detected and a leak notification is provided. This ensures that necessary countermeasures against the leak can be taken.

In the embodiment described above, a case has been described as an example in which a notification indicating that refrigerant has leaked, a notification indicating that an ignition possibility has occurred, and a notification indicating that the ignition possibility is high are provided by displaying text information on the display of the remote control 50a and by using audio information from the speaker of the remote control 50a.

However, the type of notification is not limited to these. For example, when the remote control 50a is provided with a lamp, the lamp may be turned on or made to blink. When a notification is provided by using a lamp, the notification may be provided in a different way in accordance with the determined level of the ignition possibility such that the amount of emission of light is increased, the color of emitted light is changed, or the blinking speed is increased.

When the controller <NUM> is connected to an external remote monitoring device or the like, which is constituted by a computer, via the communication unit <NUM> so that they can communicate with each other over a communication network, the controller <NUM> may transmit to the external remote monitoring device or the like information indicating that refrigerant has leaked, an ignition possibility has occurred, and the ignition possibility is high. In this case, a service engineer who specializes in taking countermeasures against refrigerant leaks that are being monitored in the remote monitoring device can also be appropriately informed of the situation.

In the embodiment described above, a case has been described as an example in which in the refrigerant leak control mode, a pump-down operation is finally performed to stop the air conditioner <NUM>.

However, the control of the air conditioner <NUM>, which is performed after an ignition possibility has occurred, is not limited to this. For example, control may be performed to reduce the frequency of the compressor <NUM> after a leak. When an ignition possibility has occurred during the execution of the cooling operation mode, the indoor expansion valve <NUM> may be closed so as not to supply further refrigerant to the indoor heat exchanger <NUM>.

For example, in a stage where an ignition possibility has only occurred, the operation of the air conditioner <NUM> may be continuously performed, with the driving of the compressor <NUM> reduced, and in a stage where the ignition possibility becomes high, a pump-down operation may be performed to stop the air conditioner <NUM>. Alternatively, for example, in a stage where an ignition possibility has only occurred, the operation of the air conditioner <NUM> may be continuously performed, with the indoor fan <NUM> forcibly driven with a maximum number of revolutions, and in a stage where the ignition possibility becomes high, a pump-down operation may be performed to stop the air conditioner <NUM>.

In the embodiment described above, a case has been described as an example in which the air temperature sensor <NUM> is included and, as illustrated in step S <NUM>, in the refrigerant leak control mode, a detection result of the air temperature sensor <NUM> is used to determine whether the ignition possibility is high.

Alternatively, for example, as illustrated in <FIG> and <FIG>, an air conditioner 100a may be used that further includes an air humidity sensor <NUM> to detect the air humidity in the space where the indoor unit <NUM> is installed. The air humidity sensor <NUM> is also electrically connected to the indoor-unit control unit <NUM> so that a detection signal can be transmitted.

As illustrated in <FIG>, the processing of steps S20 to S26, S28, and S29 is similar to that of steps S10 to S18 according to the embodiment described above, and the processing of step S27, described below, may be added after step S26.

In step S27, the controller <NUM> determines whether the humidity of indoor air detected by the air humidity sensor <NUM> is greater than or equal to a predetermined air humidity. The predetermined air humidity is determined in advance in accordance with the type of the refrigerant charged in the refrigerant circuit <NUM> (in this embodiment, R32) and is stored in the storage unit <NUM>. If the controller <NUM> determines that the humidity of indoor air detected by the air humidity sensor <NUM> is greater than or equal to the predetermined air humidity, the process proceeds to step S28. On the other hand, if it is determined that the humidity is not greater than or equal to the predetermined air humidity, the process proceeds to step S29.

In R32, distinctive difference in flammability due to a difference in air humidity is not found so much. In contrast, for example, in HFO refrigerants such as HFO-1234ze and HFO-1234yf, the ignition possibility increases as the air humidity increases. Thus, by taking humidity into account, the ignition possibility can be more accurately determined.

In the foregoing, a case has been described as an example in which both the air temperature sensor <NUM> and the air humidity sensor <NUM> are used to determine the ignition possibility. However, the ignition possibility may be determined by using the air humidity sensor <NUM> without using the air temperature sensor <NUM>.

To evaluate the ignition possibility in more detail, the refrigerant gas concentration range condition, the oxygen concentration range condition, the air temperature range condition, and the air humidity range condition may be stored in advance in accordance with the type of the refrigerant charged in the refrigerant circuit <NUM>, and the ignition possibility may be determined specifically in accordance with the type of the refrigerant charged in the refrigerant circuit <NUM>.

In the embodiment described above, a case has been described as an example in which a refrigerant leak is determined by using the concentration detected by the refrigerant gas sensor <NUM>.

As an alternative for the determination of a refrigerant leak, it may be determined that refrigerant has leaked by, for example, detecting a reduction in the pressure detected by the suction pressure sensor <NUM> or the discharge pressure sensor <NUM> (by determining that a predetermined pressure condition is satisfied). In this way, a refrigerant leak is determined by using a detected value of refrigerant pressure in the refrigerant circuit <NUM>, thereby confirming that a leak from the refrigerant circuit <NUM> has occurred (rather than the detection of refrigerant that has leaked from any other refrigerant system).

Furthermore, for example, in step S10 in the refrigerant leak control mode according to the embodiment described above, the determination is made by both detecting the refrigerant concentration by the refrigerant gas sensor <NUM> and detecting a reduction in the pressure detected by the suction pressure sensor <NUM> or the discharge pressure sensor <NUM>, thereby more accurately determining a refrigerant leak to increase reliability. To determine a reduction in the pressure detected by the suction pressure sensor <NUM> or the discharge pressure sensor <NUM>, a pressure value used as a determination criterion may be stored in the storage unit <NUM> in advance in accordance with the operation status, and the determination may be made by comparison with the pressure value serving as the determination criterion.

A reduction in the pressure detected by the suction pressure sensor <NUM> or the discharge pressure sensor <NUM>, described above, may be detected by, for example, detecting a reduction in saturation temperature in the refrigerant circuit <NUM>. In this case, for example, as a reduction in the saturation temperature of refrigerant that flows through the outdoor heat exchanger <NUM> in the cooling operation mode, a reduction in saturation temperature determined from the outdoor heat-exchange temperature sensor <NUM> may be detected, or a reduction in saturation temperature corresponding to a saturation pressure determined from the discharge pressure sensor <NUM>.

Alternatively, the concentration of refrigerant that has leaked may be determined by using, as illustrated in <FIG> and <FIG>, an air conditioner 100b that further includes an ultrasonic sensor <NUM>. The ultrasonic sensor <NUM> is constituted by an ultrasonic transmitter that emits an ultrasound wave to the interior of the room, and an ultrasonic receiver that receives an ultrasound wave reflected from the wall surface or the like of the room. If refrigerant leaks within the room, velocity changes when the ultrasound wave travels through a portion where the concentration of the refrigerant is high, and the time taken from emission to reception of the ultrasound wave changes accordingly. Based on the change, the refrigerant concentration can be determined. The ultrasonic sensor <NUM> can compare the specific gravity of refrigerant to be charged in the refrigerant circuit <NUM> with that of air to predict and use a portion where the refrigerant is likely to build up when leaking, such that the ultrasound wave is emitted downward when the refrigerant has a great specific gravity and the ultrasound wave is emitted upward when the refrigerant has a small specific gravity. The ultrasonic sensor <NUM> is also electrically connected to the indoor-unit control unit <NUM> so that a detection signal can be transmitted.

Then, for example, the determination of the refrigerant concentration in step S10 in the refrigerant leak control mode according to the embodiment described above may be performed by using both detection performed by the refrigerant gas sensor <NUM> and detection of the refrigerant concentration using the ultrasonic sensor <NUM>. In this case, if the value detected by any one of the sensors is determined to be greater than or equal to a predetermined refrigerant concentration, the process may proceed to the subsequent step.

In the embodiment described above, the air conditioner <NUM> has been described as an example in which the indoor unit <NUM> and the outdoor unit <NUM> are separately arranged in remote locations.

Alternatively, an air conditioner may be configured such that the internal components of the indoor unit <NUM> and the internal components of the outdoor unit <NUM> according to the embodiment described above are housed in a single housing, and may be used in such a manner that the single housing is mounted over the indoor side and the outdoor side.

In the embodiment described above, a case has been described as an example in which if refrigerant leaks, the indoor fan <NUM> is controlled to forcibly operate with a maximum number of revolutions.

Alternatively, for example, a controller of ventilation equipment, which is installed in the building separately from the air conditioner <NUM>, and the controller <NUM> of the air conditioner <NUM> are configured to be capable of communicating with each other, and, when the indoor fan <NUM> is caused to forcibly operate if refrigerant leaks, a fan included in the ventilation equipment may also be caused to forcibly operate at the same time.

Claim 1:
A refrigeration apparatus (<NUM>, 100a, 100b) including a refrigerant circuit (<NUM>) that has refrigerant charged therein and that performs a refrigeration cycle, the refrigeration apparatus (<NUM>) comprising:
a refrigerant gas sensor (<NUM>) for detecting a refrigerant gas in a target space where at least a portion of the refrigeration apparatus is suitable to be located; and
an oxygen gas sensor (<NUM>) for detecting an oxygen gas in the target space,
a control unit (<NUM>) configured to provide a notification indicating that an ignition possibility has occurred, or change an operation of the refrigeration cycle in the refrigerant circuit or stop the operation of the refrigeration cycle in the refrigerant circuit, on the basis of detected information obtained from the refrigerant gas sensor and the oxygen gas sensor.