Air conditioning apparatus

An air conditioning apparatus includes a casing, a heat exchanger and a blower. In the casing, an intake port is formed and a blow-off port is formed in a top surface section. The heat exchanger and the blower are housed in the casing. The blower is caused to rotate while a flammable refrigerant flows to the heat exchanger during an operation, an intake air is taken into the casing from the intake port, a heat exchange is carried out between the flammable refrigerant and the intake air in the heat exchanger, and the heat-exchanged air is blown out from the blow-off port to an exterior of the casing. A first refrigerant sensor that detects the flammable refrigerant is disposed on a downwind side of the heat exchanger inside the casing.

CROSS-REFERENCE TO RELATED APPLICATIONS

This U.S. National stage application claims priority under 35 U.S.C. § 119(a) to Japanese Patent Application No, 2014-031771, filed in Japan on Feb. 21, 2014, the entire contents of which are hereby incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to an air conditioning apparatus, and particularly relates to an air conditioning apparatus in which a flammable refrigerant is used.

BACKGROUND ART

Conventionally, there are air conditioning apparatuses that use R32 or other flammable refrigerants. Such an air conditioning apparatus is proposed in Japanese Patent Application Laid-open No. 2002-98393 in which a refrigerant sensor is provided to an outer surface of a lower section of a casing of a floor-type indoor unit to detect a leakage of the flammable refrigerant.

SUMMARY

The arrangement of the refrigerant sensor in Japanese Patent Application Laid-open No. 2002-98393 takes into account the fact that a configuration is adopted to make it possible to detect that flammable refrigerant has leaked indoors. However, the flammable refrigerant is dispersed by the flow of an air from a blower during an operation of the air conditioning apparatus, and there is therefore a possibility that the leakage of the flammable refrigerant cannot be rapidly detected.

An object of the present invention is to make it possible to rapidly detect the leakage of the refrigerant during the operation in the air conditioning apparatus that uses the flammable refrigerant.

An air conditioning apparatus according to a first aspect of the present invention has a casing in which an intake port is formed and a blow-off port is formed in atop surface section, and a heat exchanger and a blower housed in the casing, and is configured so that the blower is caused to rotate while a flammable refrigerant flows to the heat exchanger during an operation, an air is taken into the casing from the intake port, a heat exchange is carried out between the flammable refrigerant and the intake air in the heat exchanger, and the heat-exchanged air is blown out from the blow-off port to an exterior of the casing. A first refrigerant sensor for detecting the flammable refrigerant is disposed on a downwind side of the heat exchanger inside the casing.

A refrigerant sensor is preferably arranged in a position in which the flow of the air from the blower is concentrated and the majority of the leaked flammable refrigerant passes inside the casing in order to allow the leakage of the flammable refrigerant during the operation to be rapidly detected.

In view of this fact, according to the aspect described above, the first refrigerant sensor is provided to the downwind side of the heat exchanger in which the flammable refrigerant may possibly leak inside the casing.

The leakage of the flammable refrigerant during the operation can thereby be rapidly detected.

An air conditioning apparatus according to a second aspect of the present invention is the air conditioning apparatus according to the first aspect of the present invention, wherein the blower is arranged on the downwind side of the heat exchanger, and the first refrigerant sensor is arranged on an upwind side of the blower.

According to the aspect described above, the heat exchanger and the blower are arranged in the sequence of the heat exchanger and the blower with respect to the flow of the air inside the casing, and the first refrigerant sensor is arranged on the downwind side of the heat exchanger and on the upwind side of the blower. Accordingly, the detection of the flammable refrigerant by the first refrigerant sensor can suppress the influence of the atmosphere outside the casing in which the flammable refrigerant is dispersed.

It is thereby possible to increase the precision for detecting the leakage of the flammable refrigerant.

An air conditioning apparatus according to a third aspect of the present invention is the air conditioning apparatus according to the second aspect of the present invention, wherein the first refrigerant sensor is arranged in a position nearer to the blower than to the heat exchanger.

An air conditioning apparatus according to a fourth aspect of the present invention is the air conditioning apparatus according to the first aspect of the present invention, wherein the blower is arranged on the downwind side of the heat exchanger, and the first refrigerant sensor is arranged in a position nearer to the blower than to the heat exchanger.

According to the aspects described above, the first refrigerant sensor is arranged in the position nearer to the blower than to the heat exchanger. Accordingly, the degree of concentration of the airflow from the blower can be made greater than when the first refrigerant sensor is arranged in a position near the heat exchanger.

It is thereby possible to increase the precision for detecting the leakage of the flammable refrigerant.

An air conditioning apparatus according to a fifth aspect of the present invention is the air conditioning apparatus according to any of the first to fourth aspects of the present invention, wherein the blower has a propeller-type impeller, and the first refrigerant sensor is arranged in a vicinity of an external peripheral edge of the impeller.

According to the aspect described above, the first refrigerant sensor is arranged in the vicinity of the external peripheral edge of the propeller-type impeller. Accordingly, the detection of the flammable refrigerant by the first refrigerant sensor can be carried out in the position in which the velocity of the air inside the casing is greatest.

It is thereby possible to increase the precision for detecting the leakage of the flammable refrigerant.

An air conditioning apparatus according to a sixth aspect of the present invention is the air conditioning apparatus according to any of the first to fifth aspects of the present invention, wherein the intake port is formed below the blow-off port among a side surface section of the casing, and a second refrigerant sensor for detecting the flammable refrigerant is furthermore provided to a bottom surface section of the casing.

According to the aspect described above, a structure is used in which the intake port is formed below the blow-off port among the side surface section of the casing, i.e., a top-blow-type structure in which the air is taken into the casing from below and the air is blown to the exterior of the casing from above. Accordingly, when the flammable refrigerant has leaked during the operation stoppage, the flammable refrigerant, which has a high specific gravity, accumulates in the vicinity of the bottom surface section of the casing, and the first refrigerant sensor provided on the downwind side of the heat exchanger is not able to rapidly detect the leakage of the flammable refrigerant during the operation stoppage.

In view of this situation, the second refrigerant sensor is furthermore provided to the bottom surface section of the casing for the case in which the casing is the top-blow-type structure.

The leakage of the flammable refrigerant during the operation stoppage can thereby be rapidly detected.

An air conditioning apparatus according to a seventh aspect of the present invention is the air conditioning apparatus according to any of the first to fifth aspects of the present invention, wherein when the first refrigerant sensor has detected the flammable refrigerant, the blower is caused to rotate in a state in which the flammable refrigerant is not allowed to flow to the heat exchanger.

An air conditioning apparatus according to an eight aspect of the present invention is the air conditioning apparatus according to the sixth aspect of the present invention, wherein when the first refrigerant sensor or the second refrigerant sensor has detected the flammable refrigerant, the blower is caused to rotate in a state in which the flammable refrigerant is not allowed to flow to the heat exchanger.

According to the aspects described above, when the first refrigerant sensor or the second refrigerant sensor has detected the flammable refrigerant, the blower is caused to rotate in the state in which the flammable refrigerant is not allowed to flow to the heat exchanger. In other words, when the leakage of the flammable refrigerant has been detected during the operation, the compressor is stopped or other action is taken to thereby produce the state in which the refrigerant is not allowed to flow the heat exchanger, the operation of the blow is continued, and the flammable refrigerant is dispersed to the exterior of the casing. Also, when the leakage of the flammable refrigerant has been detected during the operation stoppage, the compressor is kept in the stopped state or other action is taken to thereby produce a state in which refrigerant is not allowed to flow the heat exchanger, the blower is operated, and the flammable refrigerant is disperse to the exterior of the casing.

In this case, when the leakage of the flammable refrigerant has been detected, the flammable refrigerant can be rapidly dispersed to the exterior of the casing, and the concentration of the leaked flammable refrigerant is reduced to avoid reaching ignition conditions.

DESCRIPTION OF EMBODIMENTS

An embodiment of the air conditioning apparatus according to the present invention is described below with reference to the drawings. The specific configuration of embodiments of the air conditioning apparatus according to the present invention is not limited to the embodiment and modification examples thereof described below, and modifications are possible within a range that does not depart for the scope of the invention.

(1) Basic Configuration of the Air Conditioning Apparatus

FIG. 1is a schematic structural view of the air conditioning apparatus1according to an embodiment of the present invention.

The air conditioning apparatus1is used for air conditioning the indoors of a building or the like by a vapor-compression refrigerating cycle operation. The air conditioning apparatus1is mainly configured by an outdoor unit2and an indoor unit4being connected together. In this configuration, the outdoor unit2and the indoor unit4are connected via a liquid refrigerant communication pipe5and a gas refrigerant communication pipe6. In other words, a vapor-compression refrigerant circuit10of the air conditioning apparatus1is configured by the outdoor unit2and the indoor unit4being connected together via the refrigerant communication pipes5,6. R32 or another refrigerant capable of ignition under specific conditions (hereinafter referred to as “flammable refrigerant”) is sealed as a refrigerant in the refrigerant circuit10.

The indoor unit4is disposed indoors and constitutes a portion of the refrigerant circuit10. The indoor unit4mainly has an indoor heat exchanger41.

The indoor heat exchanger41functions as an evaporator for the flammable refrigerant during an air-cooling operation to cool an indoor air, and functions as a radiator for the flammable refrigerant during an air-warming operation to heat the indoor air. The liquid side of the indoor heat exchanger41is connected to the liquid refrigerant communication pipe5, and the gas side of the indoor heat exchanger41is connected to the gas refrigerant communication pipe6.

The indoor unit4has an indoor fan42(blower) for taking the indoor air into the indoor unit4, carrying out heat exchange between the flammable refrigerant and the indoor air taken into the indoor heat exchanger41, and blowing out the heat-exchanged air to the exterior (i.e., indoors) of the indoor unit4as supplied air. In other words, the indoor unit4has an indoor fan42as a blower for supplying the indoor air to the indoor heat exchanger41as a heat source or cold source for the flammable refrigerant flowing through the indoor heat exchanger41. In this case, a centrifugal fan, multiblade fan, or the like driven by an indoor fan motor42ais used as the indoor fan42(blower).

The indoor unit4has an indoor-side control unit49for controlling the actuation of each component constituting the indoor unit4. The indoor-side control unit49has a microcomputer, memory, and the like provided for controlling the indoor unit4, and is configured so as to carry out interchange of control signals or the like with a remote control (not shown) for individually operating the indoor unit4, and to carry out interchange of control signals or the like with the outdoor unit2.

The outdoor unit2is installed outdoors and constitutes a portion of the refrigerant circuit10. The outdoor unit2mainly has a compressor21, a four-way switching valve22, an outdoor heat exchanger23, an expansion valve26, a liquid-side shutoff valve27, and a gas-side shutoff valve28.

The compressor21is a device for compressing the low-pressure flammable refrigerant in the refrigerating cycle to produce the high-pressure flammable refrigerant. The compressor21is a hermetic structure for rotatably driving a rotary-type, scroll-type, or other positive-displacement compression element (not shown) with the aid of the compressor motor21a. The compressor21has an intake pipe31connected to the intake side and a discharge pipe32connected to the discharge side. The intake pipe31is a refrigerant pipe for connecting the intake side of the compressor21and the four-way switching valve22. The discharge pipe32is a refrigerant pipe for connecting the discharge side of the compressor21and the four-way switching valve22.

The four-way switching valve22switches the direction of the flow of the flammable refrigerant in the refrigerant circuit10. During the air-cooling operation, the four-way switching valve22switches to an air-cooling cycle state for causing the outdoor heat exchanger23to function as a radiator of the flammable refrigerant compressed in the compressor21, and for causing the indoor heat exchanger41to function as an evaporator of the flammable refrigerant which has radiated heat in the outdoor heat exchanger23. In other words, during the air-cooling operation, the four-way switching valve22connects the discharge side (in this case, the discharge pipe32) of the compressor21and the gas side (in this case, a first gas refrigerant pipe33) of the outdoor heat exchanger23(see the solid line of the four-way switching valve22inFIG. 1). Also, the intake side (in this case, the intake pipe31) of the compressor21and the gas refrigerant communication pipe6side (in this case, a second gas refrigerant pipe34) are connected together (see the solid line of the four-way switching valve22inFIG. 1). During the air-warming operation, the four-way switching valve22switches to an air-warming cycle state for causing the outdoor heat exchanger23to function as an evaporator of the flammable refrigerant which has released heat in the indoor heat exchanger41, and for causing the indoor heat exchanger41to function as a radiator of the flammable refrigerant compressed in the compressor21. In other words, during the air-warming operation, the four-way switching valve22connects the discharge side (in this case, the discharge pipe32) of the compressor21and the gas refrigerant communication pipe6side (in this case, a second gas refrigerant pipe34) (see the broken line of the four-way switching valve22inFIG. 1). Also, the intake side (in this case, the intake pipe31) of the compressor21and the gas side (in this case, the first gas refrigerant pipe33) of the outdoor heat exchanger23are connected together (see the broken line of the four-way switching valve22inFIG. 11. The second gas refrigerant pipe34connects the four-way switching valve22and the gas-side shutoff valve28.

The outdoor heat exchanger23functions as a radiator of the flammable refrigerant in which an outdoor air is used as a cold source during the air-cooling operation, and functions as a compressor of the flammable refrigerant when the outdoor air is used as a heat source during the air-warming operation. The liquid side of the outdoor heat exchanger23is connected to a liquid refrigerant pipe35and the gas side is connected to the first gas refrigerant pipe33. The liquid refrigerant pipe35connects the liquid side of the outdoor heat exchanger23and the liquid refrigerant communication pipe5side.

During the air-cooling operation, the expansion valve26decompresses the high-pressure flammable refrigerant in the refrigerating cycle which has radiated heat in the outdoor heat exchanger23to the low pressure of the refrigerating cycle. During the air-warming operation, the expansion valve26decompresses the high-pressure flammable refrigerant in the refrigerating cycle which has radiated heat in the indoor heat exchanger41to the low pressure of the refrigerating cycle. The expansion valve26is provided to a portion of the liquid refrigerant pipe35nearer to a liquid-side shutoff valve27. In this case, an electrical expansion valve is used as the expansion valve26.

The liquid-side shutoff valve27and the gas-side shutoff valve28are provided to the connection ports of the exterior devices and pipes specifically, the liquid refrigerant communication pipe5and the gas refrigerant communication pipe6). The liquid-side shutoff valve27is provided to an end section of the liquid refrigerant pipe35. The gas-side shutoff valve28is provided to an end section of the second gas refrigerant pipe34.

The outdoor unit2has an outdoor fan36(blower) for taking the outdoor air into the outdoor unit2, carrying out heat exchange between the flammable refrigerant and the outdoor air taken into the outdoor heat exchanger23, and blowing out the heat-exchanged air to the exterior (i.e., outdoors) of the outdoor unit2as expelled air. In other words, the outdoor unit2has an outdoor fan36serving as a blower for supplying the outdoor air to the outdoor heat exchanger23as a heat source or cold source for the flammable refrigerant flowing through the outdoor heat exchanger23. In this case, a propeller fan driven by an outdoor fan motor36ais used as the outdoor fan36(blower).

The outdoor unit2has an outdoor-side control unit29for controlling the actuation of each component constituting the outdoor unit2. The outdoor-side control unit29has a microcomputer, memory, and/or an inverter device or the like for controlling the compressor motor21aprovided for controlling the outdoor unit2, and is configured so as to carry out interchange of control signals or the like with the indoor-side control unit49of the indoor unit4. Refrigerant sensors37,38for detecting the flammable refrigerant are provided to the outdoor unit2, and the details of arrangement or the like of the refrigerant sensors37,38are described later.

The refrigerant communication pipes5,6are installed on site when the air conditioning apparatus1is set up in a building or other installation location, and pipes having various lengths and/or diameters are used in accordance with the installation location and/or installation conditions such as the combination of the outdoor unit and the indoor unit.

The indoor-side control unit49of the indoor unit4and the outdoor-side control unit29of the outdoor unit2constitute a control unit8for controlling the operation of the air conditioning apparatus1overall, as shown inFIG. 1. The control unit8is connected so as to be capable of receiving the detection signals of various sensors including the refrigerant sensors37,38, as shown inFIG. 2. The control unit8is configured so as to be capable of carrying out the air-cooling operation, air-warming operation, and various other operations by controlling the various devices and valves21a,22,26,36a,42aon the basis of the detection signals or the like.2is a control block diagram of the air conditioning apparatus1.

As described above, the air conditioning apparatus1has a refrigerant circuit10configured by the indoor unit4being connected to the outdoor unit2via the refrigerant communication pipes5,6, R32 or another flammable refrigerant is sealed as a refrigerant in the refrigerant circuit10. The air conditioning apparatus1has the outdoor heat exchanger23serving as a heat exchanger and the outdoor fan36serving as a blower in the outdoor unit2, and has the indoor heat exchanger41as a heat exchanger and the indoor fan42as a blower in the indoor unit4. In the air conditioning apparatus1, the operation and control are carried out by the control unit8in the following manner.

(2) Basic Actuation of the Air Conditioning Apparatus

The basic actuation of the operations (the air-cooling operation and the air-warming operation) of the air conditioning apparatus1is next described with reference toFIG. 1.

When the air-cooling operation instruction has been given from the remote control or the like (not shown), the four-way switching valve22is switched to the air-cooling cycle state (the state indicated by the solid line of four-way switching valve22inFIG. 1), and the compressor21, the outdoor fan36, and the indoor fan42are started up.

At this time, the flammable refrigerant in the low-pressure gas state in the refrigerant circuit10is taken into the compressor21and compressed to become the flammable refrigerant in the high-pressure gas state. The flammable refrigerant in the high-pressure gas state is sent to the outdoor heat exchanger23(heat exchanger) by way of the four-way switching valve22. The flammable refrigerant in the high-pressure gas state sent to the outdoor heat exchanger23is condensed by heat exchange with the outdoor air fed by the outdoor fan36(blower) to be cooled and become the flammable refrigerant in the high-pressure liquid state in the outdoor heat exchanger23, which functions as a radiator for the flammable refrigerant. The flammable refrigerant in the high-pressure liquid state is decompressed by the expansion valve26to become the low-pressure flammable refrigerant in the gas-liquid two-phase state. The low-pressure flammable refrigerant in the gas-liquid two-phase state is sent from the outdoor unit2to the indoor unit4by way of the liquid refrigerant communication pipe5.

The low-pressure flammable refrigerant in the gas-liquid two-phase state sent to the indoor unit4is sent to the indoor heat exchanger41(heat exchanger). The low-pressure flammable refrigerant in the gas-liquid two-phase state sent to the indoor heat exchanger41is evaporated by heat exchange with the indoor air fed by the indoor fan42(blower) to be heated and become the low-pressure flammable refrigerant in the gas state in the indoor heat exchanger41, which functions as an evaporator of the flammable refrigerant. The low-pressure flammable refrigerant in the gas state is sent from the indoor unit4to the outdoor unit2by way of the gas refrigerant communication pipe6.

The low-pressure flammable refrigerant in the gas state sent to the outdoor unit2is again taken into the compressor21by way of the four-way switching valve22.

When the air-warming operation instruction has been given from the remote control or the like (not shown), the four-way switching valve22is switched to the air-warming cycle state (the state indicated by the broke line of four-way switching valve22inFIG. 1), and the compressor21, the outdoor fan36, and the indoor fan42are started up.

At this time, the flammable refrigerant in the low-pressure gas state in the refrigerant circuit10is taken into the compressor21and compressed to become the flammable refrigerant in the high-pressure gas state. The flammable refrigerant in the high-pressure gas state is sent from the outdoor unit2to the indoor unit4by way of the four-way switching valve22and the gas refrigerant communication pipe6.

The flammable refrigerant in the high-pressure gas state sent to the indoor unit4is sent to the indoor heat exchanger41(heat exchanger). The flammable refrigerant in the high-pressure gas state sent to the indoor heat exchanger41is condensed by heat exchange with the indoor air fed by the indoor fan42(blower) to be cooled and become the flammable refrigerant in the high-pressure liquid state in the indoor heat exchanger41, which functions as a radiator for the flammable refrigerant. The flammable refrigerant in the high-pressure liquid state is sent from the indoor unit4to the outdoor unit2by way of the liquid refrigerant communication pipe5.

The flammable refrigerant in the high-pressure liquid state sent to the indoor unit is decompressed by the expansion valve26to become the low-pressure flammable refrigerant in the gas-liquid two-phase state. The low-pressure flammable refrigerant in the gas-liquid two-phase state is sent to the outdoor heat exchanger23(heat exchanger). The low-pressure flammable refrigerant in the gas-liquid two-phase state thusly sent to the outdoor heat exchanger23is evaporated by heat exchange with the outdoor air fed by the outdoor fan36(blower) to be heated and become the low-pressure flammable refrigerant in the gas state in the outdoor heat exchanger23, which functions as an evaporator of the flammable refrigerant. The low-pressure flammable refrigerant in the gas state is again taken into the compressor21by way of the four-way switching valve22.

(3) Structure of the Outdoor Unit, Arrangement of the Refrigerant Sensors, and Control for Dispersing the Flammable Refrigerant to the Apparatus Exterior

<Structure of the Outdoor Unit>

The structure of the outdoor unit2constituting the air conditioning apparatus1is next described with reference toFIGS. 1 to 4.FIG. 3is a schematic perspective view (with a fan grill78removed) of the outdoor unit2, andFIG. 4is a front view (with a front panel75removed) of the outdoor unit2. “Front,” “rear,” “left,” and “right” in the description below is based on viewing the outdoor unit2from the front panel75side. InFIGS. 3 and 4, components other than the outdoor heat exchanger23and the outdoor fan36are omitted from the drawings.

The outdoor unit2has a top-blow-type structure in which the air is taken into the casing71from below and the air is blown to the exterior of the casing71from above.

The casing71in this example is a substantially rectangular parallelepiped-shaped box, and mainly has a top surface panel72constituting a top surface section of the casing71, a left-side surface panel73, a right-side surface panel74, the front-side surface panel75, and a rear-side surface panel76constituting side surface sections of the casing71, and a bottom surface panel77constituting the bottom surface section of the casing71. The top surface panel72is a member constituting the top surface section of the casing71, and is mainly a panel-shaped member having a substantially rectangular shape as viewed from above and in which a blow-off port72ais formed substantially in the center. The fan grill78is formed in the top surface panel72so as to cover the blow-off port72afrom above. The left-side surface panel73is mainly a member constituting the left-side surface section of the casing71, and is a panel-shaped member having a substantially rectangular shape as viewed from the side and which extends downward from the left edge of the top surface panel72. Intake ports73aare formed in essentially the entire left-side surface panel73excluding the upper section. The right-side surface panel74is mainly a member constituting the right-side surface section of the casing71, and is a panel-shaped member having a substantially rectangular shape as viewed from the side and which extends downward from the right edge of the top surface panel72. Intake ports74aare formed in essentially the entire right-side surface panel74excluding the upper section. The front-side surface panel75is mainly a member constituting the front-side surface section of the casing71, and is a panel-shaped member having a substantially rectangular shape as viewed from the side and which is arranged in sequence downward from the front edge of the top surface panel72. The rear-side surface panel76is mainly a member constituting the rear-side surface section of the casing71, and is a panel-shaped member having a substantially rectangular shape as viewed from the side and which is arranged in sequence downward from the rear edge of the top surface panel72. Intake ports76aare formed in essentially the entire rear-side surface panel76excluding the upper section. The bottom surface panel77is mainly a member constituting the bottom surface section of the casing71, and is a panel-shaped member having a substantially rectangular shape as viewed from above. In other words, the intake ports73a,74a,76aand the blow-off port72aare formed in the casing71. In this example, the blow-off port72ais formed in the top surface section (in this example, the top surface panel72) of the casing71, and the intake ports73a,74a,76aare formed in the side surface sections (in this example, the left-side surface panel73, the right-side surface panel74, the front-side surface panel75, and the rear-side surface panel76) of the casing71below the blow-off port72a. In this example, the blow-off port72ais formed as an opening that faces upward in the top surface panel72constituting the top surface section of the casing71, but no limitation is imposed thereby. For example, the blow-off port72amay be formed as an opening that faces laterally in the upper section of the side surface panels73to76constituting the side surface sections of the casing71. In such case, the upper sections of the side surface panels73to76would also constitute the top surface section of the casing71.

Such a casing71houses various components including the outdoor heat exchanger23serving as a heat exchanger and the outdoor fan36serving as a blower. The air conditioning apparatus1is configured so that the outdoor fan36serving as a blower is caused to rotate while the flammable refrigerant is allowed to flow to the outdoor heat exchanger23serving as a heat exchanger during the above-described air-cooling operation, air-warming operation, and/or other operations in the outdoor unit2, the air (in this example, the outdoor air) is taken from the intake ports73a,74a,76ainto the casing71, a heat is exchanged between the flammable refrigerant and the air (in this example, the outdoor air) taken into the outdoor heat exchanger23serving as a heat exchanger, and the heat-exchanged air (in this example, outdoor air) is blown out from the blow-off port72ato the exterior of the casing71. In this case, the outdoor heat exchanger23serving as a heat exchanger is substantially U-shaped as viewed from above, and is arranged to as to face the intake ports73a,74a,76a. In this example, the outdoor fan36serving as a blower is arranged on the downwind side of the outdoor heat exchanger23serving as a heat exchanger and above the outdoor heat exchanger23. The outdoor fan36serving as a blower has a propeller-type impeller36b, and the outdoor fan motor36afor rotatably driving the propeller-type impeller36b. The outdoor fan motor36ais supported by the casing71via a motor support base79, and the propeller-type impeller36bis connected to a rotating shaft extending upward from the outdoor fan motor36aalong the rotational axis O-O.

<Arrangement of the Refrigerant Sensors>

In the air conditioning apparatus1that uses R32 or other flammable refrigerant, the flammable refrigerant is liable to leak during the operation in the outdoor unit2. For example, there may be cases in which abnormal vibrations occur due to a failure of the compressor21or other cause, and heat transfer tubes and/or refrigerant pipes of the outdoor heat exchanger23serving as a heat exchanger are damaged. Accordingly, it is preferred that refrigerant sensors for detecting the leakage of the flammable refrigerant be provided to the air conditioning apparatus1as conventionally proposed.

However, in a conventional refrigerant sensor arrangement, the flammable refrigerant is dispersed by the flow of the air from the blower during the operation of the air conditioning apparatus and it is possible that the leakage of the flammable refrigerant cannot be rapidly detected.

In view of the above, first, in this example, the first refrigerant sensor37for detecting the flammable refrigerant is provided on the downwind side of the outdoor heat exchanger23serving as a heat exchanger inside the casing71, as shown inFIGS. 3 and 4. The reason for providing the first refrigerant sensor37for detecting the flammable refrigerant on the downwind side of the outdoor heat exchanger23serving as a heat exchanger inside the casing71is that a refrigerant sensor is preferably arranged in a position where the flow of the air (in this example, the outdoor air) from the outdoor fan36serving as a blower is concentrated inside the casing71and where the majority of the leaked flammable refrigerant would pass so that the leakage of flammable refrigerant can be rapidly detected during the operation.

In accordance with the foregoing, the leakage of the flammable refrigerant during the operation (the air-cooling operation and/or the air-warming operation or the like) can be rapidly detected. The flammable refrigerant has a high specific gravity and therefore tends to readily accumulate in the vicinity of the bottom surface section (bottom surface panel77) of the casing71. Accordingly, the leakage of the flammable refrigerant during the operation (the air-cooling operation and/or the air-warming operation or the like) may not be rapidly detected when the first refrigerant sensor37is arranged in the position other than the downwind side of the outdoor heat exchanger23such as in the vicinity of the bottom surface section (bottom surface panel77) of the casing71. However, in this example, the first refrigerant sensor37is arranged in the position on the downwind side of the outdoor heat exchanger23in the vicinity of the top surface section (in this example, the top surface panel72) of the casing71, and concentrating the flow of the air during the operation (the air-cooling operation and/or the air-warming operation or the like) makes it possible to rapidly detect the leakage of the flammable refrigerant.

In this example, the first refrigerant sensor37is arranged so as to be on the upwind side of the outdoor fan36serving as a blower, as shown inFIGS. 3 and 4. In other words, the outdoor heat exchanger23serving as a heat exchanger and the outdoor fan36serving as a blower are arranged in the sequence of the outdoor heat exchanger23serving as a heat exchanger and the outdoor fan36serving as a blower with respect to the flow of the air (in this example, the outdoor air) in the casing71, and the first refrigerant sensor37is arranged on the downwind side of the outdoor heat exchanger23serving as a heat exchanger and on the upwind side of the outdoor fan36serving as a blower. Accordingly, detection of the flammable refrigerant by the first refrigerant sensor37can be made less likely to be affected by the atmosphere outside the casing71and in which the flammable refrigerant has been dispersed (in this case, the atmosphere outside the casing71through the blow-off port72a). In this example, the first refrigerant sensor37is attached to the motor support base79.

It is thereby possible to increase the precision for detecting the leakage of the flammable refrigerant.

Also, in this example, the first refrigerant sensor37is arranged in the position nearer to the outdoor fan36(specifically, the propeller-type impeller36b) serving as a blower than to the outdoor heat exchanger23serving as a heat exchanger, as shown inFIG. 4. Accordingly, it is thereby possible to improve the degree of concentration of the flow of the air (in this example, the outdoor air) from the outdoor fan36serving as a blower in comparison with when the first refrigerant sensor37is arranged in the position near the outdoor heat exchanger23serving as a heat exchanger.

It is thereby possible to increase the precision for detecting the leakage of the flammable refrigerant.

Also, in this example, the first refrigerant sensor37is arranged in the vicinity of the external peripheral edge of the propeller-type impeller36bconstituting the outdoor fan36serving as a blower, as shown inFIG. 4. The first refrigerant sensor37is preferably arranged within a range of 0.25 r to the internal peripheral side from the external peripheral edge (i.e., the position in the circumferential direction of the radius r) of the propeller-type impeller36b, where r is the radius of the propeller-type impeller36bas viewed from above. Alternatively, the first refrigerant sensor37is preferably arranged within a range of 0.25 r to the external peripheral side from the external peripheral edge (i.e., the position in the circumferential direction of the radius r) of the propeller-type impeller36b. In this example, the first refrigerant sensor37is arranged within a range of 0.25 r to the internal peripheral side from the external peripheral edge (i.e., the position in the circumferential direction of the radius r) of the propeller-type impeller36b. Accordingly, the detection of the flammable refrigerant by the first refrigerant sensor37can be carried out in the position in which the velocity of the air (in this example, the outdoor air) inside the casing71is greatest.

It is thereby possible to increase the precision for detecting the leakage of the flammable refrigerant.

In the air conditioning apparatus1, the leakage of the flammable refrigerant is also liable to occur during the operation stoppage in the outdoor unit2. For example, there are cases in which the flammable refrigerant has leaked during the operation and the operation has stopped with the situation unchanged, or the heat transfer tubes and/or refrigerant pipes of the outdoor heat exchanger23serving as a heat exchanger are damaged during transport, delivery, and installation work.

However, in this example, the structure is used in which the blow-off port72ais formed in the top surface section (in this example, the top surface panel72) of the casing71, and the intake ports73a,74a,76aare formed in the side surface sections (the left-side surface panel73, right-side surface panel74, front-side surface panel75, and rear-side surface panel76) of the casing71below the blow-off port72a, i.e., the top-blow-type structure in which the air (in this example, the outdoor air) is taken into the casing71from below and the air (in this example, the outdoor air) is blown to the exterior of the casing71from above. Accordingly, when the flammable refrigerant has leaked during the operation stoppage, the flammable refrigerant, which has a high specific gravity, accumulates in the vicinity of the bottom surface section (the bottom surface panel77) of the casing71, and the first refrigerant sensor37provided on the downwind side of the outdoor heat exchanger23serving as a heat exchanger is not able to rapidly detect the leakage of the flammable refrigerant during the operation stoppage.

In view of this situation, in this example, the second refrigerant sensor38is furthermore provided to the bottom surface section of the casing71(in the vicinity of the bottom surface panel77) when the casing71having the top-blow-type structure is used, as shown inFIGS. 3 and 4. In this example, the second refrigerant sensor38is arranged in the position slightly above the bottom surface panel77.

The leakage of the flammable refrigerant during the operation stoppage can thereby be rapidly detected.

<Control for Dispersing the Flammable Refrigerant to the Apparatus Exterior>

When the leakage of the flammable refrigerant has been detected by the first refrigerant sensor37and/or the second refrigerant sensor38described above, the flammable refrigerant is preferably rapidly dispersed to the exterior of the casing71and the concentration of the leaked flammable refrigerant is reduced so as to avoid reaching ignition conditions.

In view of the above, in this example, when the first refrigerant sensor37and/or the second refrigerant sensor38has detected the flammable refrigerant, the control for dispersing the flammable refrigerant to the apparatus exterior is carried out in which the outdoor fan36serving as a blower is caused to rotate in a state in which the flammable refrigerant is not allowed to flow to the outdoor heat exchanger23serving as a heat exchanger.

The control for dispersing the flammable refrigerant to the apparatus exterior is next described with reference toFIGS. 1 to 5.FIG. 5is a flowchart of the control for dispersing the flammable refrigerant to the apparatus exterior. The control for dispersing the flammable refrigerant to the apparatus exterior is carried out by the control unit8.

Specifically, first, in step ST1, it is determined whether the first refrigerant sensor37and/or the second refrigerant sensor38has detected the flammable refrigerant. During the operation, it is highly likely that it is the first refrigerant sensor37that detects the flammable refrigerant, and during the operation stoppage, it is highly likely that it is the second refrigerant sensor38that detects the flammable refrigerant. When the flammable refrigerant has been detected in step ST1, the process proceeds to step ST2.

Next, in step ST2, it is determined whether the current state of the air conditioning apparatus1is operating or stoppage. When the current state of the air conditioning apparatus1is an operating state in step ST2, the process proceeds to step ST3, and when the current state of the air conditioning apparatus1is a stopped state, the process proceeds to step ST4.

Next, in step ST3, the outdoor fan36serving as a blower is caused to rotate in a state in which the flammable refrigerant is not allowed to flow to the outdoor heat exchanger23serving as a heat exchanger. Specifically, the compressor21is stopped or other action is taken to yield a state in which the refrigerant is not allowed to flow to the outdoor heat exchanger23serving as a heat exchanger and the operation of the outdoor fan36serving as a blower is continued. The flammable refrigerant can thereby be dispersed to the exterior of the casing71. At this time, the outdoor fan36is preferably operated at maximum speed in order to accelerate the dispersion of the flammable refrigerant. In step ST4as well, the outdoor fan36serving as a blower is caused to rotate in a state in which the flammable refrigerant is not allowed to flow to the outdoor heat exchanger23serving as a heat exchanger. Specifically, the stoppage of the compressor21is maintained or other action is taken to form a state in which the refrigerant is not allowed to flow to the outdoor heat exchanger23serving as a heat exchanger and the operation of the outdoor fan36serving as a blower is carried out. The flammable refrigerant can thereby be dispersed to the exterior of the casing71. At this time as well, the outdoor fan36is preferably operated at maximum speed in order to accelerate the dispersion of the flammable refrigerant.

In the embodiment described above, the outdoor heat exchanger23serving as a heat exchanger is substantially U-shaped as viewed from above, but no limitation is imposed thereby. For example, the heat exchanger may have another shape such as substantially V-shaped as viewed from the side.

Described in the embodiment above and modification thereof were examples in which the refrigerant sensors37,38are provided to the outdoor unit2, but no limitation is imposed thereby. For example, the refrigerant sensors37,38may be provided to the indoor unit4. For example, it is possible to use the same arrangement of the refrigerant sensors37,38of the present invention when the indoor unit4is a floor-type indoor unit having a structure in which an air (in this case, the indoor air) is taken into a casing from below and the air (in this case, the indoor air) is blown out to the exterior of the case from above.

Described in the embodiment above and modifications thereof were examples in which the refrigerant circuit10of the air conditioning apparatus1can be switched between the air-cooling operation and the air-warming operation by a four-way switching valve22, but no limitation is imposed thereby. For example, the present invention can be applied to an air conditioning apparatus having a refrigerant circuit dedicated to the air-cooling operation or to the air-warming operation.

INDUSTRIAL APPLICABILITY

The present invention can be widely applied to air conditioning apparatuses in which a flammable refrigerant is used.