The present invention relates to a heating dedicated air conditioner.

In the conventional art, when an air conditioner is installed, a test operation is often performed in order to verify whether, for example, the various equipment of the air conditioner operates normally, the air conditioner has been constructed correctly, and the like. For example, in an air conditioner according to Patent Document 1 (i.e., Japanese Unexamined Patent Application Publication No. 2001-99459), a test operation is performed in a cooling cycle or a heating cycle; furthermore, in this test operation, a verification is simultaneously performed to determine whether the indoor fan is operating normally.

Among the air conditioners discussed above, there are heating dedicated air conditioners that principally perform heating operation. In such a heating dedicated air conditioner, only heating operation is performed, and this principally in the winter season when the temperature is low; therefore, a drainage pipe that serves as drain water processing equipment is often not provided and only a drain pan is provided. Consequently, for example, in the summertime when the temperature and humidity are high, if a test operation of the heating dedicated air conditioner is performed in a reverse cycle to that of the heating cycle discussed above, then drain water from the indoor heat exchanger may overflow the drain pan and flow into the indoor space, which would be a problem.

Accordingly, an object of the present invention is to prevent drain water from an indoor heat exchanger from overflowing a drain pan in a case wherein a test operation of a heating dedicated air conditioner is performed in a reverse cycle to that of the heating cycle, for example, in summertime when the temperature and humidity are high.

A heating dedicated air conditioner according to a first aspect of the present invention comprises a compression mechanism, an indoor heat exchanger, an outdoor heat exchanger, an expansion mechanism, a four-way switching valve, a fan, and a control unit. The expansion mechanism is provided between one end of the indoor heat exchanger and one end of the outdoor heat exchanger. The four-way switching valve switches between a first state, wherein a discharge side of the compression mechanism and an other end of the indoor heat exchanger are connected and a suction side of the compression mechanism and an other end of the outdoor heat exchanger are connected, and a second state, wherein the discharge side of the compression mechanism and the other end of the outdoor heat exchanger are connected and the suction side of the compression mechanism and the other end of the indoor heat exchanger are connected. The fan ventilates the indoor heat exchanger. The control unit controls at least the compression mechanism, the expansion mechanism, the four-way switching valve, and the fan. In addition, the control unit, in the test operation mode, switches the four-way switching valve to the second state. Furthermore, the drain water inhibited interval during which drain water inhibition control is performed, wherein the control unit operates the compression mechanism and stops the fan, is provided to the test operation mode.

Here, in the heating dedicated air conditioner, if a drain pan is disposed, for example, below the indoor heat exchanger, then it is possible to accumulate drain water generated in the indoor heat exchanger. In addition, for example, the expansion mechanism is an expansion valve whose degree of opening may be fixed.

In the heating dedicated air conditioner according to the first aspect of the invention, the control unit, in the test operation mode, switches the four-way switching valve from the first state to the second state and stops the fan. Thereby, for example, in the heating dedicated air conditioner, it is possible to prevent drain water from overflowing the drain pan even if the drain pan alone is provided without drainage pipe that externally discharges the drain water accumulated in the drain pan, for example, even if test operation is performed in the summertime in a reverse cycle to that of a heating cycle.

A heating dedicated air conditioner according to a second aspect of the present invention is the heating dedicated air conditioner according to the first aspect of the invention, and further comprises a gas side shutoff valve and a pressure detector. The gas side shutoff valve is provided between the other end of the indoor heat exchanger and the four-way switching valve. The pressure detector is mounted to a gas refrigerant pipe that connects the other end of the indoor heat exchanger and the suction side of the compression mechanism.

In the heating dedicated air conditioner according to the second aspect of the invention, test operation in, for example, the test operation mode is performed in the state wherein the four-way switching valve is in the second state, namely, in the reverse cycle to that of the heating cycle. This is because, should test operation be performed in the heating cycle, the high pressure between the gas side shutoff valve and the discharge side of the compression mechanism will tend not to rise, and it might not be possible to promptly detect whether the gas side shutoff valve is in the open state, which is a problem. Thereby, the open/close state of the gas side shutoff valve in the test operation mode can be promptly detected by performing, for example, test operation in the test operation mode in the reverse cycle to that of the heating cycle and providing the pressure detector to the gas refrigerant pipe that connects the other end of the indoor heat exchanger and the suction side of the compression mechanism.

A heating dedicated air conditioner according to a third aspect of the present invention is the heating dedicated air conditioner according to the second aspect of the invention, and further comprises an indoor casing and an outdoor casing. The indoor heat exchanger and the fan are housed in the indoor casing. The compression mechanism, the outdoor heat exchanger, the expansion mechanism, the four-way switching valve, the gas side shutoff valve, and the pressure detector are housed in the outdoor casing.

In the heating dedicated air conditioner according to the third aspect of the invention, it is possible to prevent the drain water from overflowing the drain pan even if test operation is performed in the summertime.

A heating dedicated air conditioner according to a fourth aspect of the present invention is the heating dedicated air conditioner according to any one aspect of the first through third aspects of the invention, and further comprises a gas-liquid separator. The gas-liquid separator is provided between the suction side of the compression mechanism and the four-way switching valve.

In the heating dedicated air conditioner according to the fourth aspect of the invention, the amount of evaporation of the refrigerant in the indoor heat exchanger decreases because the fan is stopped. Consequently, the amount of the liquid refrigerant increases more than when the fan is operating. Accordingly, providing the gas-liquid separator makes it possible to prevent the liquid from being sucked into the compressor,

A heating dedicated air conditioner according to a fifth aspect of the present invention is the heating dedicated air conditioner according to any one aspect of the first through fourth aspects of the invention, wherein the drain water inhibited interval occupies 80% or more of the entire interval of the test operation mode.

In the heating dedicated air conditioner according to the fifth aspect of the invention, it is possible to reduce the amount of indoor air delivered from the fan to the indoor heat exchanger by stopping the fan for an interval that is 80% or more of the entire interval. Thereby, even if the fan is driven, it is possible to prevent the drain water from overflowing the drain pan.

A heating dedicated air conditioner according to a sixth aspect of the present invention is the heating dedicated air conditioner according to the fifth aspect of the invention, wherein in the test operation mode, a first interval other than the drain water inhibited interval is a beginning interval of the entire interval of the test operation mode.

In the heating dedicated air conditioner according to the sixth aspect of the invention, the fan is driven during the beginning interval in the test operation mode when the evaporation temperature does not fall all that much. Thereby, it is possible to prevent the drain water from overflowing the drain pan even if the fan is driven.

In the heating dedicated air conditioner according to the first aspect of the invention, the control unit, in the test operation mode, switches the four-way switching valve from the first state to the second state and stops the fan. Thereby, for example, in the heating dedicated air conditioner, it is possible to prevent drain water from overflowing the drain pan even if the drain pan alone is provided without drainage pipe that externally discharges the drain water accumulated in the drain pan, for example, even if test operation is performed in the summertime in a reverse cycle to that of a heating cycle.

In the heating dedicated air conditioner according to the second aspect of the invention, the open/close state of the gas side shutoff valve in the test operation mode can be promptly detected by performing, for example, test operation in the test operation mode in the reverse cycle to that of the heating cycle and providing the pressure detector to the gas refrigerant pipe that connects the other end of the indoor heat exchanger and the suction side of the compression mechanism.

In the heating dedicated air conditioner according to the third aspect of the invention, it is possible to prevent the drain water from overflowing the drain pan even if test operation is performed in the summertime.

In the heating dedicated air conditioner according to the fourth aspect of the invention, the amount of evaporation of the refrigerant in the indoor heat exchanger decreases because the fan is stopped. Consequently, the amount of the liquid refrigerant increases more than when the fan is operating. Accordingly, providing the gas-liquid separator makes it possible to prevent the liquid from being sucked into the compressor.

In the heating dedicated air conditioner according to the fifth and sixth aspects of the invention, even if the fan is driven, it is possible to prevent the drain water from overflowing the drain pan.

• FIG. 1 is a system diagram of a refrigerant circuit of a heating dedicated air conditioner.
• FIG. 2 is a control block diagram of a control unit.
• FIG 3 is a flow chart that illustrates operation during a test operation of the heating dedicated air conditioner according to a second embodiment.

The embodiments of the present invention will now be explained, referencing the drawings.

The heating dedicated air conditioner 1 is used to heat an indoor space of a building by performing a vapor compression type refrigeration cycle operation. As shown in FIG. 1, the heating dedicated air conditioner 1 comprises a single outdoor unit 2 that serves as a heat source unit, a single indoor unit 4 that serves as a utilization unit and is connected to the outdoor unit 2, and a liquid side refrigerant connection pipe 6 and a gas side refrigerant connection pipe 7 that serve as refrigerant connection pipes and connect the outdoor unit 2 and the indoor unit 4. Namely, a refrigerant circuit 10 of the heating dedicated air conditioner 1 is configured by the connection of the outdoor unit 2, the indoor unit 4, the liquid side refrigerant connection pipe 6, and the gas side refrigerant connection pipe 7.

First, the configuration of the indoor unit 4 will be explained.

The indoor unit 4 is installed either by embedding it in or suspending it from the ceiling of the indoor space of a building or by mounting it to a wall surface of the indoor space. The indoor unit 4 is connected to the outdoor unit 2 via the liquid side refrigerant connection pipe 6 and the gas side refrigerant connection pipe 7.

The indoor unit 4 principally comprises an indoor side refrigerant circuit 10a, which constitutes part of the refrigerant circuit 10. The indoor side refrigerant circuit 10a principally comprises an indoor heat exchanger 42.

The indoor heat exchanger 42 is a cross fin type fin and tube heat exchanger, which comprises a heat transfer tube and numerous fins; during heating operation, the indoor heat exchanger 42 functions as a condenser that condenses a refrigerant (e.g., a fluorocarbon based refrigerant) and heats indoor air. Furthermore, during defrosting operation and during test operation, discussed below, (i.e., in the state wherein the refrigerant circuit 10 is in a reverse cycle to that of the heating cycle), it functions as an evaporator that evaporates the refrigerant.

In addition, the indoor unit 4 comprises an indoor fan 43 (refer to FIG. 2). The indoor fan 43 functions as a ventilation fan, which is for sucking the indoor air into the indoor unit 4, causing heat to be exchanged between that air and the refrigerant in the indoor heat exchanger 42, and then supplying that air to the indoor space as supply air. In addition, the indoor fan 43 is driven by a fan motor (not shown) and is capable of varying the airflow of the air supplied to the indoor heat exchanger 42. The fan motor is configured such that it is driven by receiving the supply of electric power via an inverter apparatus (not shown); furthermore, by varying the inverter frequency, which varies the fan rotational speed, the airflow of the indoor fan 43 can be varied.

Furthermore, below the indoor heat exchanger 42, the indoor unit 4 is provided with a drain pan 45. The drain pan 45 serves to receive any drain water generated in the indoor heat exchanger 42 in the state wherein the refrigerant circuit 10 is in the reverse cycle to that of the heating cycle. Furthermore, a drainage pipe for discharging the drain water is not provided.

Next, the configuration of the outdoor unit 2 will be explained.

The outdoor unit 2 is installed in the outdoor space outside of a building and is connected to the indoor unit 4 via the liquid side refrigerant connection pipe 6 and the gas side refrigerant connection pipe 7. Furthermore, the outdoor unit 2 principally comprises an outdoor side refrigerant circuit 10b, which constitutes part of the refrigerant circuit 10. The outdoor side refrigerant circuit 10b principally comprises: a compressor 21; a four-way switching valve 22; an outdoor heat exchanger 23, which serves as a heat source heat exchanger; an outdoor expansion valve 24, which serves as an expansion mechanism; an accumulator 25; a liquid side shutoff valve 26; and a gas side shutoff valve 27.

The compressor 21 is capable of varying the operating capacity and is a displacement type compressor that is driven by a compressor motor (not shown).

The four-way switching valve 22 is for the purpose of switching the flow direction of the refrigerant and can assume a first state (refer to the broken lines of the four-way switching valve 22 in FIG. 1) and a second state (refer to the solid lines of the four-way switching valve 22 in FIG. 1). In the first state, the discharge side of the compressor 21 and the gas side of the indoor heat exchanger 42 (specifically, the gas side refrigerant connection pipe 7) are connected, and the suction side of the compressor 21 (specifically, the accumulator 25) and the gas side of the outdoor heat exchanger 23 are connected. Namely, when the four-way switching valve 22 is in the first state, the refrigerant circuit 10 is in the heating cycle. In the second state, the discharge side of the compressor 21 and the gas side of the outdoor heat exchanger 23 are connected, and the suction side of the compressor 21 and the gas side of the indoor heat exchanger 42 are connected. Namely, when the four-way switching valve 22 is in the second state, the refrigerant circuit 10 is in the state wherein it is in the reverse cycle to that of the heating cycle, that is, in the cooling cycle state.

The outdoor heat exchanger 23 is a cross fin type fin and tube heat exchanger, which comprises heat transfer tubes and numerous fins. The outdoor heat exchanger 23 functions as an evaporator that evaporates the refrigerant during the heating operation. The gas side of the outdoor heat exchanger 23 is connected to the four-way switching valve 22, and the liquid side is connected to the liquid side refrigerant connection pipe 6. Furthermore, when the four-way switching valve 22 is in the second state, the outdoor heat exchanger 23 functions as a condenser that condenses the refrigerant.

The outdoor expansion valve 24 is a motor operated expansion valve that is provided between one end of the indoor heat exchanger 42 and one end of the outdoor heat exchanger 23 and is connected to the liquid side of the outdoor heat exchanger 23. The outdoor expansion valve 24 regulates the pressure, the flow volume, and the like of the refrigerant that flows through the interior of the outdoor side refrigerant circuit 10b.

The outdoor unit 2 comprises an outdoor fan 28 (refer to FIG. 2). The outdoor fan 28 functions as a ventilation fan, which is for sucking outdoor air into the outdoor unit 2, causing heat to be exchanged between that air and the refrigerant in the outdoor heat exchanger 23, and then discharging that air to the outdoor space. In addition, the outdoor fan 28 is capable of varying the amount of the outdoor air supplied to the outdoor heat exchanger 23, and is a propeller fan that is driven by a fan motor (not shown).

The accumulator 25 is a vessel that is provided between the four-way switching valve 22 and the suction side of the compressor 21 and is capable of accumulating surplus refrigerant generated inside the refrigerant circuit 10 in accordance with fluctuations in the operating loads of the indoor unit 4.

The liquid side shutoff valve 26 and the gas side shutoff valve 27 are provided to a connection port that connects to external equipment and pipe (specifically, the liquid side refrigerant connection pipe 6 and the gas side refrigerant connection pipe 7). The liquid side shutoff valve 26 is connected to the outdoor heat exchanger 23. The gas side shutoff valve 27 is connected to the four-way switching valve 22. The liquid side shutoff valve 26 and the gas side shutoff valve 27 have a function that seals the refrigerant with which the outdoor unit 2 is initially filled. Generally, when a builder mounts the heating dedicated air conditioner 1, he or she completes the refrigerant circuit 10 by connecting onsite the indoor unit 4 and the outdoor unit 2 using the liquid side refrigerant connection pipe 6 and the gas side refrigerant connection pipe 7 and, afterward, manually sets the liquid side shutoff valve 26 and the gas side shutoff valve 27 to an open state. Thereby, the refrigerant that is sealed inside the outdoor unit 2 (specifically, the outdoor heat exchanger 23) is made to spread to the refrigerant circuit 10.

In addition, the outdoor unit 2 is provided with a refrigerant pressure sensor 33, which detects the pressure of the refrigerant between the four-way switching valve 22 and the gas side shutoff valve 27.

The liquid side refrigerant connection pipe 6 and the gas side refrigerant connection pipe 7 are refrigerant pipes that are laid onsite when the heating dedicated air conditioner 1 is installed at an installation location inside a building; refrigerant pipes of various lengths and diameters are used for the pipes 6, 7 in accordance with the installation conditions such as the installation location and the particular combination of the outdoor unit 2 and indoor unit 4 to be configured.

A control unit 9 comprises a microcomputer, memory, and the like and, as shown in FIG. 2, comprises an indoor control unit 9a and an outdoor control unit 9b. The indoor control unit 9a controls the operation of the various equipment (specifically, the indoor fan 43 and the like) that constitutes the indoor unit 4. The outdoor control unit 9b controls the operation of the various equipment (specifically, the compressor 21, the outdoor fan 28, and the like) that constitutes the outdoor unit 2.

The indoor control unit 9a is capable of transmitting control signals to and receiving control signals from a remote controller (not shown), which is for separately operating the indoor unit 4. In addition, the indoor control unit 9a and the outdoor control unit 9b are configured such that they can transmit control signals between and receive control signals from one another via a transmission line. Furthermore, the control unit 9, which comprises the indoor control unit 9a and the outdoor control unit 9b, is connected to the refrigerant pressure sensor 33 such that the control unit 9 can receive a detection signal therefrom and is configured such that it can control the rotational speed of the indoor fan 43 and the outdoor fan 28, the rotational speed of the compressor 21, and the like based on the detection signal, a control signal from the remote controller, and the like.

Furthermore, prescribed threshold values are set in the control unit 9 for the low pressure side pressure and the high pressure side pressure detected by the refrigerant pressure sensor 33, and fluctuations, either upward or downward, in the low pressure side pressure and the high pressure side pressure are detected on the basis of these threshold values. Furthermore, this detection makes it possible to know whether there is an abnormal condition in any of the various equipment of the heating dedicated air conditioner 1. For example, during a test operation in a test operation mode, discussed below, when the gas side shutoff valve 27 is in not the open but the closed state, the pressure detected by the refrigerant pressure sensor 33 falls below the threshold value of the low pressure side pressure.

The principal operation modes of the heating dedicated air conditioner 1 are a normal operation mode, wherein the various equipment of the outdoor unit 2 and the indoor unit 4 is controlled in accordance with the operating load of the indoor unit 4, and the test operation mode, which is for verifying, for example, whether the various equipment of the outdoor unit 2 and the indoor unit 4 is operating normally, and whether the construction is correct (e.g., whether the liquid side shutoff valve 26 and the gas side shutoff valve 27 are in the open state). In the normal operation mode, heating operation is principally performed. In the test operation mode, test operation is performed. Furthermore, test operation is performed after the installation of the various equipment of the heating dedicated air conditioner 1 (specifically, test operation is not limited to being performed after the initial installation of the equipment, and may be performed, for example, after making modifications such as adding or removing various equipment of the outdoor unit 2 and the indoor unit 4, after repairing an equipment failure, and the like).

The following text explains the operation of the heating dedicated air conditioner 1 in each of the operation modes, referencing FIG. 1. Furthermore, the operation of the heating dedicated air conditioner 1 is performed by the control unit 9.

First, heating operation in the normal operation mode will be explained.

During heating operation, control is performed such that the four-way switching valve 22 is in the first state. Namely, the four-way switching valve 22 is controlled such that the state obtains wherein the discharge side of the compressor 21 is connected to the gas side of the indoor heat exchanger 42 via the gas side shutoff valve 27 and the gas side refrigerant connection pipe 7, and the suction side of the compressor 21 is connected to the gas side of the outdoor heat exchanger 23.

Furthermore, in this state, if the compressor 21, the outdoor fan 28, and the indoor fan 43 are driven, then the low pressure gas refrigerant is suctioned into the compressor 21 and therefore is compressed and transitions to high pressure gas refrigerant. This high pressure gas refrigerant is delivered to the indoor unit 4 via the four-way switching valve 22, the gas side shutoff valve 27, and the gas side refrigerant connection pipe 7. In the indoor heat exchanger 42, the heat of the high pressure gas refrigerant delivered to the indoor unit 4 is exchanged with the indoor air supplied by the indoor fan 43, and thereby that refrigerant is condensed and transitions to high pressure liquid refrigerant. The high pressure liquid refrigerant is delivered to the outdoor unit 2 via the liquid side refrigerant connection pipe 6 and the liquid side shutoff valve 26. Furthermore, the pressure of the high pressure liquid refrigerant delivered to the outdoor unit 2 is reduced by the outdoor expansion valve 24, and that refrigerant transitions to refrigerant in a low pressure gas-liquid two-phase state and is delivered to the outdoor heat exchanger 23. In the outdoor heat exchanger 23, the heat of the liquid refrigerant in the low pressure gas-liquid two-phase state is exchanged with the outdoor air supplied by the outdoor fan 28, and thereby that refrigerant evaporates and transitions to low pressure gas refrigerant. This low pressure gas refrigerant flows into the accumulator 25 via the four-way switching valve 22 and then once again is suctioned into the compressor 21.

Accordingly, the outdoor heat exchanger 23 functions as an evaporator that evaporates the refrigerant. However, if the heating operation of the heating dedicated air conditioner 1 is performed under the condition wherein the temperature of the outdoor air, which is the heat source of the outdoor heat exchanger 23, is low, then one can assume that frost will adhere to the surface of the outdoor heat exchanger. Furthermore, if frost does adhere to the surface of the outdoor heat exchanger, then there is a risk that the heat exchange performance of the outdoor heat exchanger will decrease. Accordingly, in the heating dedicated air conditioner 1, when frost adheres to the outdoor heat exchanger 23 during heating operation, the four-way switching valve 22 is temporarily switched from the first state to the second state and defrosting operation is performed as below.

During defrosting operation, control is performed such that the four-way switching valve 22 is in the second state. Namely, the four-way switching valve 22 is controlled such that a state obtains wherein the discharge side of the compressor 21 is connected to the gas side of the outdoor heat exchanger 23, and the suction side of the compressor 21 is connected to the gas side of the indoor heat exchanger 42 via the gas side shutoff valve 27 and the gas side refrigerant connection pipe 7.

In this state, if the compressor 21 is driven, first, the low pressure gas refrigerant is suctioned into the compressor 21 where it is compressed and transitions to high pressure gas refrigerant. Furthermore, the high pressure gas refrigerant is delivered to the outdoor heat exchanger 23 via the four-way switching valve 22, its heat is exchanged with the outdoor air in the outdoor heat exchanger 23, and thereby condenses and transitions to high pressure liquid refrigerant. At this time, the frost or the ice that adheres to the surface of the outdoor heat exchanger 23 melts owing to the heat emitted from the high pressure gas refrigerant, which is undergoing the heat exchange process. Furthermore, during defrosting operation, control is performed such that the outdoor fan 28 is in the stopped state.

Furthermore, the outdoor expansion valve 24 reduces the pressure of the high pressure liquid refrigerant, which transitions to refrigerant in the low pressure gas-liquid two-phase state and is delivered to the indoor unit 4 via the liquid side shutoff valve 26 and the liquid side refrigerant connection pipe 6. The refrigerant in the low pressure gas-liquid two-phase state delivered to the indoor unit 4 is then delivered to the indoor heat exchanger 42; the heat of that refrigerant is exchanged with the indoor air at the indoor heat exchanger 42, and thereby that refrigerant evaporates and transitions to low pressure gas refrigerant. At this time, the indoor fan 43 is controlled such that it is in the stopped state. This is done in order to prevent cold air from potentially being blown out into the indoor space when the indoor fan 43 is operating, thereby reducing the comfort of users of the indoor space.

Furthermore, the low pressure gas refrigerant is delivered to the outdoor unit 2 via the gas side refrigerant connection pipe 7 and the gas side shutoff valve 27, and then flows into the accumulator 25 via the four-way switching valve 22. Furthermore, the low pressure liquid refrigerant that does not evaporate at the indoor heat exchanger 42 because the indoor fan 43 is stopped accumulates in the accumulator 25.

Furthermore, the low pressure gas refrigerant that flows into the accumulator 25 is once again sucked into the compressor 21.

Test operation in the test operation mode will be explained next. Note that test operation is performed by a worker operating an operation button, which is provided to a remote controller (not shown) and is for setting the operation mode to the test operation mode. In addition, the test operation interval, which is the entire interval during which test operation is performed in the test operation mode, is set in advance (e.g., to three minutes); furthermore, when the set test operation interval ends, the mode switches to the operation mode set by the user via the remote controller (i.e., to heating operation in the normal operation mode).

Here, ordinarily, test operation is often performed in the state wherein the four-way switching valve 22 is controlled such that it is in the second state (i.e., when the refrigerant circuit is in the so-called cooling cycle state). This is because if test operation is performed during the heating cycle, then the pressure detected by the refrigerant pressure sensor 33 will tend not to rise, and consequently it could become difficult to promptly detect whether the shutoff valve (e.g., the gas side shutoff valve 27) is in the open state.

However, in a heating dedicated air conditioner, drainage work, such as for discharging drain water accumulated in a drain pan to the outdoor space, is often not undertaken. Consequently, if the heating dedicated air conditioner is used and test operation is performed during the cooling cycle in, for example, a high temperature and high humidity location or during a high temperature and high humidity season (e.g., summertime), then the refrigerant that flows through the interior of an indoor heat exchanger will take the heat of the indoor air delivered to the indoor heat exchanger by an indoor fan, and thereby a large amount of drain water is assumed to be generated in the indoor heat exchanger. Therefore, even if the drain water generated in the indoor heat exchanger could be accumulated in the drain pan, if the amount of the drain water exceeds the capacity of the drain pan to store water, then it is conceivable that the drain water will overflow the drain pan and flow into the indoor space.

Accordingly, during test operation of the heating dedicated air conditioner 1, drain water inhibition control, which operates the compressor 21 and stops the indoor fan 43, is performed. A drain water inhibited interval, during which drain water inhibition control is performed, is the same as the test operation interval. Namely, in the heating dedicated air conditioner 1, the indoor fan 43 is always stopped during test operation in the test operation mode.

Thereby, the generation of drain water is inhibited because the heat exchange efficiency between the refrigerant and the indoor air in the indoor heat exchanger 42 is lower than when the indoor fan 43 is being operated. Thereby, it is possible to prevent the drain water from overflowing the drain pan 45.

Furthermore, the operation of the heating dedicated air conditioner 1 during test operation is substantially the same as the operation of the heating dedicated air conditioner 1 during defrosting operation. However, during defrosting operation, the outdoor fan 28 is stopped, whereas, during test operation, the outdoor fan 28 is operated and the degree of opening of the outdoor expansion valve 24 is fixed.

In the first embodiment, test operation is performed in the state wherein the four-way switching valve 22 is in the second state. Furthermore, during test operation, the indoor fan 43 is stopped.

Thereby, the indoor fan 43 no longer delivers the indoor air to the indoor heat exchanger 42, and therefore the amount of the indoor air whose heat is exchanged with the refrigerant in the indoor heat exchanger 42 decreases. Accordingly, because the drain water generated in the indoor heat exchanger 42 also decreases, it becomes possible to prevent the drain water from overflowing the drain pan 45, even during the summer. In addition, because the drain water does not overflow the drain pan 45, it is possible to also prevent the drain water from flowing into the indoor space. In addition, drain work also thereby becomes unnecessary.

In the first embodiment, the indoor fan 43 is stopped during test operation and during defrosting operation. Consequently, the amount of evaporation of the refrigerant flowing through the indoor heat exchanger 42 is assumed to be less than when the indoor fan 43 is being operated. Furthermore, it is conceivable that the reduced amount of evaporation of the refrigerant flowing through the indoor heat exchanger 42 causes not only the gas refrigerant but also the refrigerant in the gas-liquid two-phase state to flow out of the indoor heat exchanger 42 and to the outdoor unit 2 side.

Accordingly, because the provision of the accumulator 25 between the suction side of the compressor 21 and the four-way switching valve 22 makes it possible to accumulate the liquid refrigerant in the accumulator 25 even if the refrigerant in the gas-liquid two-phase state flows to the outdoor unit 2 side, it is possible to cause the gas refrigerant alone to be suctioned to the compressor 21. Thereby, it is possible to prevent damage to the compressor 21.

The above text explained an embodiment of the present invention based on the drawings, but the specific constitution is not limited to that embodiment, and it is understood that variations and modifications may be effected without departing from the spirit and scope of the invention.

The abovementioned embodiment explained a case that is limited to a separate type heating dedicated air conditioner 1, wherein one indoor unit 4 is connected to one outdoor unit 2, but the present invention is not limited thereto; for example, the present invention may be adapted to an integrated type heating dedicated air conditioner, wherein the outdoor unit 2 and the indoor unit 4 are integrated.

In addition, the abovementioned embodiment explained a case limited to a so-called paired heating dedicated air conditioner 1, wherein one indoor unit 4 is connected to one outdoor unit 2, but the present invention is not limited thereto. For example, the present invention may be adapted to a so-called multi type heating dedicated air conditioner, wherein a plurality of the indoor units is connected to one outdoor unit 2.

In the abovementioned embodiment, the refrigerant is not limited to fluorocarbon based refrigerant, and may be a natural refrigerant such as CO₂ refrigerant.

Continuing, a second embodiment of the heating dedicated air conditioner 1 will now be explained. Note that components and the like identical to those in the first embodiment are assigned the same symbols, and explanations thereof are therefore omitted.

The second embodiment differs from the first embodiment as follows: in the first embodiment, the indoor fan 43 is always stopped during test operation in the test operation mode; however, in the second embodiment, there is a case wherein the indoor fan 43 is operated, and is not always stopped, during test operation.

The text below explains the operation during test operation of the heating dedicated air conditioner 1 in the second embodiment, referencing FIG. 3.

FIG. 3 is a flow chart that illustrates operation during test operation of the heating dedicated air conditioner 1 according to the second embodiment.

First, in a step S101, the four-way switching valve 22 is controlled such that it is in the second state, as in the first embodiment. Furthermore, in a step S102, the compressor 21 and the outdoor fan 28 are driven, as in the first embodiment. At this time, in the first embodiment, the indoor fan 43 is always stopped during test operation in the test operation mode, and consequently the indoor fan 43 is not driven; however, in the second embodiment, the indoor fan 43 is driven in addition to the compressor 21 and the outdoor fan 28.

Next, in a step S103, it is determined whether the indoor fan 43 is operating normally. If it is determined that it is operating normally, then the process transitions to a step S104; if, however, it is determined that it is not operating normally, then the process transitions to a step S105.

In the step S104, drain water inhibition control is performed, as in the first embodiment. Namely, the compressor 21 maintains its operation state as is, and the indoor fan 43 stops.

In the step S105, it has been determined that the indoor fan 43 is not operating normally, and therefore a warning is displayed via a reporting unit (not shown; e.g., an LED or a character display).

Accordingly, in the heating dedicated air conditioner 1 according to the second embodiment, the interval during which the indoor fan 43 is driven (corresponding to a first interval) is approximately 5-10 s. Thereby, the drain water inhibited interval, which is the interval during which the drain water inhibition control is performed, occupies 80% or more (specifically, approximately 94%-97%) of the test operation interval (e.g., 3 minutes).

In addition, as discussed above, the interval during which the indoor fan 43 is driven is the beginning interval in the test operation interval. This is because drain water tends to be generated if the indoor fan 43 is driven when the evaporation temperature has fallen.

Furthermore, as in the indoor fan 43, a warning is displayed even if the compressor 21, the outdoor fan 28, or the like is not being driven normally.

In the heating dedicated air conditioner 1 according to the second embodiment, the indoor fan 43 can be driven during test operation in the test operation mode, which is effective if, for example, one wishes to verify whether the indoor fan 43 is operating normally.

In addition, in the heating dedicated air conditioner 1 according to the second embodiment, the drain water inhibited interval, which is the interval during which drain water inhibition control is performed, occupies 80% or more of the test operation interval.

During test operation in the test operation mode, it is possible to reduce the amount of the indoor air delivered from the indoor fan 43 to the indoor heat exchanger 42 by stopping the indoor fan 43 for an interval that is 80% or more of the entire interval. Thereby, the amount of drain water generated in the indoor heat exchanger 42 decreases. Accordingly, even if the indoor fan 43 is driven in order to verify whether the indoor fan 43 is operating normally, it is still possible to prevent the drain water from overflowing the drain pan 45.

In addition, in the heating dedicated air conditioner 1 according to the second embodiment, the interval during which the indoor fan 43 is driven is the beginning interval in the test operation interval. Namely, the indoor fan 43 is driven in the beginning interval during test operation when the evaporation temperature does not drop all that much. Thereby, it is possible to prevent the drain water from overflowing the drain pan 45 even if the indoor fan 43 is driven in order to verify whether the indoor fan 43 is operating normally. In addition, drain work also thereby becomes unnecessary.

In the abovementioned embodiments, the indoor fan 43 is driven in order to verify whether it is operating normally, but the present invention is not limited thereto; the indoor fan 43 may be driven as discussed above for some other purpose. Even so, the same effects as those discussed above are obtained.

In the present invention, if test operation of the heating dedicated air conditioner is performed in the reverse cycle to that of the heating cycle in, for example, summertime when the temperature and humidity are high, then it is possible to prevent drain water generated in the indoor heat exchanger from overflowing the drain pan, thereby making drain work unnecessary, which is useful.

1

Heating dedicated air conditioner

2

Outdoor casing (outdoor unit)

4

Indoor casing (indoor unit)

7

Gas side refrigerant connection pipe (gas refrigerant pipe)

9

Control unit

21

Compressor (compression mechanism)

22

Four-way switching valve

23

Outdoor heat exchanger

24

Outdoor expansion valve (expansion mechanism)

25

Accumulator (gas-liquid separator)

27

Gas side shutoff valve

33

Refrigerant pressure sensor (pressure detector)

42

Indoor heat exchanger

43

Indoor fan (fan)

• Patent Document 1
  Japanese Unexamined Patent Application Publication No. 2001-99459