WO2020110301A1 - Refrigeration cycle apparatus - Google Patents

Abstract

This refrigeration cycle apparatus is provided with: a compressor; a condenser; a decompression device; an evaporator; and a blower fan. The evaporator includes a fin (30) and a heat transfer pipe (20). The fin (30) includes a first region (30a) into which the heat transfer pipe (20) is inserted, and a second region (30b) which projects from the heat transfer pipe (20) in a direction opposite to a blowing direction during a heating operation. An outdoor fan is configured to blow air from the second region (30b) toward the first region (30a) during the heating operation, and blow air from the first region (30a) toward the second region (30b) after execution of a defrosting operation, during the heating operation, for melting frost deposited on the evaporator.

Description

Refrigeration cycle equipment

The present invention relates to a refrigeration cycle device.

Conventionally, a fin-and-tube heat exchanger including a plurality of plate-shaped fins and a plurality of heat transfer tubes that penetrate the plurality of fins in the direction in which the plurality of fins are arranged is known. A fin-and-tube type heat exchanger may use a heat transfer tube having a flat cross section. In a heat exchanger using flat heat transfer tubes, for example, when the outside air temperature is below freezing and the heat exchanger operates as an evaporator (during heating operation), the heat transfer tube surrounding the heat transfer tube is on the windward side in the blowing direction. Frost is likely to occur on the part of the evaporator. For this reason, the formation of frost on the fins tends to block the air passages provided between the plurality of fins.

For example, Japanese Patent No. 3264525 (Patent Document 1) describes a heat exchanger capable of suppressing the formation of frost on the windward ends of the fins in the blowing direction. In the heat exchanger described in this publication, by increasing the width of the windward end portion to make the temperature of the windward end portion higher than the temperature of the heat transfer tube, frost is formed at the windward end portion. This can be suppressed. Therefore, it is possible to prevent the air passages provided between the plurality of fins from being closed due to the formation of frost on the windward end portion.

Japanese Patent No. 3264525

However, the heat exchanger described in the above publication cannot suppress the formation of frost on parts other than the windward end. Therefore, the defrosting operation is required to melt the frost that has frosted around the heat transfer tubes and the portions around the heat transfer tubes of the fins. This frost is melted by the defrosting operation to form water drops. When the defrosting operation is finished, the frosting operation is started again, so that air is blown to the heat exchanger. Therefore, the water droplets generated in the defrosting operation travel rearward in the air blowing direction along the surface of the flat heat transfer tube and stay in the upper part or the lower part of the flat heat transfer tube. Therefore, the water droplets generated in the defrosting operation are not properly discharged.

The present invention has been made in view of the above problems, and an object thereof is to suppress the formation of frost at the site of the evaporator on the windward side in the blowing direction during the heating operation, and in the defrosting operation. An object of the present invention is to provide a refrigeration cycle device that can appropriately discharge generated water droplets.

The refrigeration cycle device of the present invention includes a compressor, a condenser, a pressure reducing device, an evaporator, and a blower fan. The compressor compresses the refrigerant. The condenser condenses the refrigerant compressed by the compressor. The decompression device decompresses the refrigerant condensed by the condenser. The evaporator evaporates the refrigerant decompressed by the decompression device. The blower fan blows air to the evaporator. The evaporator includes fins and heat transfer tubes that are inserted into the fins and have a flat cross section. The fin includes a first region in which the heat transfer tube is inserted and a second region protruding from the heat transfer tube in a direction opposite to the air blowing direction in the heating operation. The blower fan blows air from the second region to the first region in the heating operation and directs the first region to the second region after the defrosting operation is performed to melt the frost accumulated on the evaporator in the heating operation. It is configured to blow air.

According to the refrigeration cycle apparatus of the present invention, the fin includes the second region protruding from the heat transfer tube in the direction opposite to the air blowing direction in the heating operation. For this reason, it is possible to prevent frost formation on the part of the evaporator on the windward side in the blowing direction during the heating operation. The blower fan is configured to blow air from the first region to the second region after the defrosting operation is performed. For this reason, since the water droplets generated in the defrosting operation are discharged along the second region, the water droplets generated in the defrosting operation can be appropriately discharged.

It is a figure which shows an example of the refrigerant circuit diagram of the refrigerating cycle device which concerns on Embodiment 1 of this invention. It is a perspective view which shows an example of the outdoor heat exchanger shown by FIG. It is a partial cross section figure of the outdoor heat exchanger shown by FIG. FIG. 3 is a partial side view of the outdoor heat exchanger shown in FIG. 2. It is a partial cross section of the modification of the evaporator which concerns on Embodiment 1 of this invention. It is a time chart which shows control of the air conditioner which concerns on Embodiment 1 of this invention. It is a flowchart which shows the control of the air conditioner which concerns on Embodiment 1 of this invention. It is a time chart which shows control of an air conditioner of a comparative example. It is a flow chart which shows control of an air harmony machine of a comparative example. 7 is a time chart showing control of the air conditioner according to Embodiment 2 of the present invention. It is a time chart which shows control of the air conditioner which concerns on Embodiment 3 of this invention. It is a time chart which shows control of the air conditioner which concerns on Embodiment 4 of this invention. It is a partial cross section figure of the evaporator of the air conditioner which concerns on Embodiment 5 of this invention. It is a partial side view of the evaporator of the air conditioner concerning Embodiment 5 of the present invention. It is a figure which shows an example of the refrigerant circuit diagram of the refrigerating cycle device which concerns on Embodiment 6 of this invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following, the same or corresponding parts will be denoted by the same reference symbols and description thereof will not be repeated in principle.

Embodiment 1.
A refrigeration cycle apparatus 1 according to Embodiment 1 of the present invention will be described with reference to FIG. Refrigeration cycle device 1 of the present embodiment is, for example, an air conditioner. As shown in FIG. 1, the refrigeration cycle device 1 includes a compressor 2, an indoor heat exchanger 3, an indoor fan 4, a pressure reducing device 5, an outdoor heat exchanger 10, an outdoor fan 6, and a four-way valve. 7, a temperature sensor 8, and a control device 100 are mainly provided. For example, the compressor 2, the outdoor heat exchanger 10, the pressure reducing device 5, the outdoor fan 6, the four-way valve 7, the temperature sensor 8 and the control device 100 are housed in the outdoor unit 1a, and the indoor heat exchanger 3 and the indoor fan 4 are included. Are housed in the indoor unit 1b.

By connecting the compressor 2, the indoor heat exchanger 3, the decompression device 5, the outdoor heat exchanger 10 and the four-way valve 7 by piping, a refrigerant circuit capable of circulating a refrigerant is configured. The refrigeration cycle apparatus 1 performs a refrigeration cycle in which the refrigerant circulates in the refrigerant circuit while changing its phase.

The compressor 2 compresses the refrigerant. The compressor 2 is configured to compress the sucked refrigerant and discharge it. The compressor 2 has a variable capacity. The compressor 2 is configured so that the capacity is changed by adjusting the rotation speed by changing the frequency based on an instruction from the control device 100. The compressor 2 is, for example, a rotary compressor, a scroll compressor, a screw compressor, a reciprocating compressor, or the like.

The indoor heat exchanger 3 is for exchanging heat between the refrigerant flowing in the indoor heat exchanger 3 and the indoor air. The indoor heat exchanger 3 is connected to the pressure reducing device 5 and the four-way valve 7. The indoor heat exchanger 3 functions as a condenser that condenses the refrigerant compressed by the compressor 2 during the heating operation, and functions as an evaporator that evaporates the refrigerant decompressed by the decompression device 5 during the cooling operation. The indoor heat exchanger 3 is, for example, a fin-and-tube heat exchanger, a microchannel heat exchanger, a shell-and-tube heat exchanger, a heat pipe heat exchanger, a double-tube heat exchanger, or a plate heat exchanger. It is a container etc.

The pressure reducing device 5 expands the refrigerant to reduce the pressure. The decompression device 5 is configured to decompress the refrigerant condensed by the condenser. The decompression device 5 is, for example, an electric expansion valve capable of adjusting the flow rate of the refrigerant. The decompression device 5 may be not only an electric expansion valve, but also a mechanical expansion valve having a diaphragm for a pressure receiving portion, a capillary tube, or the like.

The indoor fan 4 is attached to the indoor heat exchanger 3 and supplies indoor air as a heat exchange fluid to the indoor heat exchanger 3. The indoor fan 4 blows air to the indoor heat exchanger 3. The indoor fan 4 adjusts the amount of air flowing around the indoor heat exchanger 3 by adjusting the number of rotations of the indoor fan 4 based on an instruction from the control device 100, and thereby the room air and the refrigerant are separated from each other. It is configured to adjust the amount of heat exchange of.

The outdoor heat exchanger 10 is for exchanging heat between the refrigerant flowing in the outdoor heat exchanger 10 and the outdoor air. The outdoor heat exchanger 10 is connected to the pressure reducing device 5 and the four-way valve 7. The outdoor heat exchanger 10 functions as an evaporator that evaporates the refrigerant decompressed by the decompression device 5 during the heating operation, and functions as a condenser that condenses the refrigerant compressed by the compressor 2 during the cooling operation. The outdoor heat exchanger 10 is a fin-and-tube heat exchanger. Details of the outdoor heat exchanger 10 will be described later.

The outdoor fan 6 is attached to the outdoor heat exchanger 10 and supplies outdoor air to the outdoor heat exchanger 10. The outdoor fan 6 blows air to the outdoor heat exchanger 10. The outdoor fan 6 adjusts the amount of air flowing around the outdoor heat exchanger 10 by adjusting the number of revolutions of the outdoor fan 6 based on an instruction from the control device 100, and thereby the air between the outdoor air and the refrigerant is adjusted. It is configured to adjust the amount of heat exchange of. The outdoor fan 6 is an axial fan. The outdoor fan 6 is configured so that the rotation direction of the outdoor fan 6 can be switched between a forward direction and a reverse direction. The outdoor fan 6 rotates in the forward direction during the heating operation, and rotates in the reverse direction during the cooling operation and the defrosting operation.

The four-way valve 7 can switch the flow path of the refrigerant in the refrigeration cycle apparatus 1. During the heating operation, the four-way valve 7 is switched so as to connect the discharge port of the compressor 2 to the indoor heat exchanger 3 and connect the suction port of the compressor 2 to the outdoor heat exchanger 10. The four-way valve 7 connects the discharge port of the compressor 2 and the outdoor heat exchanger 10 and connects the suction port of the compressor 2 and the indoor heat exchanger 3 during the cooling operation and the dehumidifying operation. Can be switched.

The temperature sensor 8 is for measuring the temperature of the refrigerant flowing through the outdoor heat exchanger 10. The temperature sensor 8 is provided in the refrigerant circuit so as to detect the liquid pipe temperature of the outdoor heat exchanger 10.

The control device 100 is configured to perform calculations, instructions and the like to control each means, equipment and the like of the refrigeration cycle apparatus 1. The control device 100 is electrically connected to the compressor 2, the indoor fan 4, the pressure reducing device 5, the outdoor fan 6, the four-way valve 7, the temperature sensor 8 and the like, and is configured to control the operations of these. ..

The configuration of the outdoor heat exchanger 10 according to the present embodiment will be described in detail with reference to FIGS. 2 to 4. FIG. 2 shows the external appearance of the outdoor heat exchanger 10 according to this embodiment. In FIG. 2 and subsequent figures, the X direction is the lateral direction and represents the lateral direction of the fins 30 of the outdoor heat exchanger 10, that is, the width direction. The Y direction is the lateral direction, and represents the direction in which the fins 30 forming the same heat exchange section are arranged in parallel. The Z direction is the vertical direction, that is, the direction of gravity, and represents the longitudinal direction of the fins 30.

In FIG. 2, a white arrow indicates the flow direction of the air supplied to the outdoor heat exchanger 10 by the outdoor fan 6 shown in FIG. 1 during the heating operation. In the outdoor heat exchanger 10 according to the present embodiment, air is supplied in the X direction by the outdoor fan 6 shown in FIG. 1 during the heating operation.

FIG. 3 shows a main part when the outdoor heat exchanger 10 is viewed from the Y direction. FIG. 4 shows a main part when the outdoor heat exchanger 10 is viewed from the X direction. 3 and 4, two heat transfer tubes 20 arranged side by side in the Z direction are shown.

The outdoor heat exchanger 10 is, for example, a two-row structure heat exchanger, and includes a windward heat exchanger 10a and a leeward heat exchanger 10b. Each of the windward side heat exchanger 10a and the leeward side heat exchanger 10b is a fin and tube type heat exchanger. The windward-side heat exchanger 10a and the leeward-side heat exchanger 10b are arranged side by side along the flow direction of the air supplied from the outdoor fan 6 shown in FIG. 1, that is, the X direction that is the blowing direction. The windward side heat exchanger 10a is arranged on the windward side in the blowing direction of the air supplied by the outdoor fan 6 shown in FIG. 1, and the leeward side heat exchanger 10b is the blowing direction of the air supplied by the outdoor fan 6. It is located on the lee side.

-One end of the heat transfer pipe 20 of the windward heat exchanger 10a is connected to the windward header collecting pipe 10c. One end of the heat transfer pipe 20 of the leeward heat exchanger 10b is connected to the leeward header collecting pipe 10d. The other end of the heat transfer tube 20 of the windward heat exchanger 10a and the other end of the heat transfer tube 20 of the leeward heat exchanger 10b are connected to the inter-row connection member 10e.

In the outdoor heat exchanger 10 according to the present embodiment, one of the windward header collecting pipe 10c and the leeward header collecting pipe 10d is connected to the one heat transfer pipe 20 of the windward heat exchanger 10a and the leeward heat exchanger 10b. The refrigerant is distributed. The refrigerant distributed to the one heat transfer tube 20 of the upwind heat exchanger 10a or the downwind heat exchanger 10b passes through the inter-row connection member 10e, and the upwind heat exchanger 10a and the downwind heat exchanger. It flows into the other heat transfer tube 20 of 10b. After that, the refrigerant flowing into the other heat transfer pipe 20 of the windward heat exchanger 10a and the leeward heat exchanger 10b merges with the other of the windward header collecting pipe 10c and the leeward header collecting pipe 10d, and is shown in FIG. To the suction port of the compressor 2 or the pressure reducing device 5.

In the present embodiment, the windward heat exchanger 10a and the leeward heat exchanger 10b have the same configuration. Therefore, the windward heat exchanger 10a will be described below as a representative of both. In addition, when the heat exchange load of the outdoor heat exchanger 10 can be covered by one of the windward side heat exchanger 10a and the leeward side heat exchanger 10b, only one of the windward side heat exchanger 10a and the leeward side heat exchanger 10b can be used to generate the outdoor heat. The exchanger 10 may be configured.

Referring to FIGS. 3 and 4, the outdoor heat exchanger 10 includes a plurality of heat transfer tubes 20 and a plurality of fins 30. The plurality of heat transfer tubes 20 are arranged so that their tube axes are oriented in the Y direction. The plurality of heat transfer tubes 20 penetrate the plurality of fins 30. The plurality of heat transfer tubes 20 are arranged in parallel in the Z direction. The plurality of heat transfer tubes 20 are arranged at intervals.

The heat transfer tube 20 has a flat cross section. The heat transfer tube 20 has a flat shape having a long axis and a short axis in a cross section perpendicular to the tube axis. The major axis of the heat transfer tube 20 is oriented in the X direction. The heat transfer tube 20 is inserted into the fin 30.

The fin 30 is a plate-shaped body. The fins 30 are attached to the heat transfer tubes 20 so that the plate surfaces of the fins 30 intersect the tube axis of the heat transfer tubes 20. The fins 30 are formed in a rectangular shape whose longitudinal direction is the direction in which the plurality of heat transfer tubes 20 are arranged in parallel. That is, the longitudinal direction of the fin 30 is along the Z direction, and the width direction orthogonal to the longitudinal direction of the fin 30 is along the X direction.

The fin 30 is provided with an insertion portion IP into which the heat transfer tube 20 is inserted. The insertion portion IP is a notch provided in the second end edge 32 of the fin 30. The heat transfer tube 20 is inserted into the insertion portion IP. The fin 30 has a first end edge 31 which is one end edge in the X direction and a second end edge 32 which is the other end edge in the X direction. The first edge 31 is located on the leeward side during the heating operation, and the second edge 32 is located on the leeward side during the heating operation.

The heat transfer tube 20 is configured so that the refrigerant flows inside. Heat is exchanged between the air sent to the outdoor heat exchanger 10 and the refrigerant flowing inside the heat transfer tube 20. The heat transfer tube 20 has a first end 20a that is one end in the X direction and a second end 20b that is the other end in the X direction. The first end 20a is located on the windward side during heating operation, and the second end 20b is located on the leeward side during heating operation. An imaginary line connecting the first ends 20a of the plurality of heat transfer tubes 20 is defined as a straight line L1. An imaginary line connecting the second ends 20b of the plurality of heat transfer tubes 20 is defined as a straight line L2.

The plurality of fins 30 are installed side by side along the tube axis direction of the heat transfer tube 20. The fins 30 adjacent to each other are arranged with a gap FP therebetween. The outdoor heat exchanger 10 is configured so that air passes through the gap FP. The fins 30 come into contact with the air passing through the gap FP and transfer heat to the refrigerant flowing inside the heat transfer tubes 20. In the first embodiment, the longitudinal direction of the fin 30 coincides with the gravity direction G.

The fin 30 includes a first area 30a and a second area 30b. The first area 30a is an area in which the heat transfer tube 20 is inserted. The first region 30a is a region located between the second edge 32 and the straight line L1 in the X direction. The second region 30b projects from the heat transfer tube 20 in a direction opposite to the air blowing direction in the heating operation. The second region 30b is a region located between the first edge 31 and the straight line L1 in the X direction. The second area 30b is an area where the heat transfer tube 20 is not installed. Therefore, in the second region 30b, the heat transfer tubes 20 do not hinder the flow of water such as dew condensation water and frost melting water flowing from the upper portions of the fins 30.

The outdoor fan 6 blows air from the second area 30b toward the first area 30a in the heating operation, and after the defrosting operation of melting the frost that has frosted on the evaporator in the heating operation is performed, the outdoor fan 6 moves from the first area 30a to the first area 30a. The air is blown toward the two areas 30b. That is, in the heating operation, air is blown from the second area 30b toward the first area 30a as indicated by an arrow F1 in FIG. After the defrosting operation is performed, air is blown from the first area 30a toward the second area 30b as indicated by an arrow F2 in FIG.

The amount of air blown by the outdoor fan 6 from the first area 30a to the second area 30b after the defrosting operation is performed, rather than the amount of air sent from the second area 30b to the first area 30a in the heating operation. May be large. This makes it possible to promote drainage.

Referring to FIG. 5, the fin 30 may include the third region 30c. The third region 30c projects from the heat transfer tube 20 in the air blowing direction in the heating operation. The third region 30c is a region located between the second edge 32 and the straight line L2 in the X direction. In the third region 30c, a cutout that is connected to the insertion portion IP is formed. In the X direction, the width of the third region 30c is smaller than the width of the second region 30b.

Next, each operation of the refrigeration cycle apparatus 1 according to the present embodiment will be described with reference to FIG. 1 again. In FIG. 1, the flow of the refrigerant in the cooling operation is indicated by a dashed arrow, and the flow of the refrigerant in the heating operation is indicated by a solid arrow.

First, the cooling operation of the refrigeration cycle apparatus 1 will be described with reference to FIG. 1 again.
The high-temperature and high-pressure vapor refrigerant compressed by the compressor 2 reaches the outdoor heat exchanger 10 via the four-way valve 7 and is condensed by radiating heat to the outdoor air blown by the outdoor fan 6 to generate high pressure. It becomes the liquid refrigerant of. The high-pressure liquid refrigerant is decompressed by expanding in the decompression device 5, and becomes a low-temperature low-pressure gas-liquid two-phase refrigerant. The low-temperature low-pressure gas-liquid two-phase refrigerant reaches the indoor heat exchanger 3 from the decompression device 5 and absorbs heat from the indoor air blown by the indoor fan 4 to be evaporated and become a low-pressure vapor refrigerant. This low-pressure vapor refrigerant returns to the compressor 2 via the four-way valve 7 and is compressed in the compressor 2 to circulate in the refrigerant circuit.

Next, the heating operation of the refrigeration cycle device 1 will be described.
The high-temperature and high-pressure vapor refrigerant compressed in the compressor 2 reaches the indoor heat exchanger 3 via the four-way valve 7 and is condensed by radiating heat to the indoor air blown by the indoor fan 4 to generate high pressure. It becomes the liquid refrigerant of. The high-pressure liquid refrigerant is decompressed by expanding in the decompression device 5, and becomes a low-temperature low-pressure gas-liquid two-phase refrigerant. The low-temperature low-pressure gas-liquid two-phase refrigerant reaches the outdoor heat exchanger 10 from the pressure reducing device 5 and absorbs heat from the outdoor air blown by the outdoor fan 6 to evaporate and become a low-pressure vapor refrigerant. The low-pressure vapor refrigerant returns to the compressor 2 via the four-way valve 7 and is compressed in the compressor 2 to circulate in the refrigerant circuit.

When the outside air temperature is low during the heating operation, the temperature of the outdoor heat exchanger 10 falls below 0° C., so that the outdoor heat exchanger 10 is frosted. That is, the water vapor in the outside air is cooled by the outdoor heat exchanger 10 and becomes frost and adheres to the outdoor heat exchanger 10. This frost increases as the heating operation continues, and blocks the air passage of the outdoor heat exchanger 10. If this frost blocks the air passage of the outdoor heat exchanger 10, it causes a decrease in heat exchange performance. Therefore, during the heating operation, the defrosting operation is performed periodically (for example, once every several tens of minutes) to melt the frost in the outdoor heat exchanger 10.

Next, the defrosting operation of the refrigeration cycle device 1 will be described. During the heating operation, when the pipe temperature measured by the outdoor heat exchanger 10 becomes a certain value or less, or when the heating operation continues for a certain time or longer, the control device 100 causes the outdoor heat exchanger 10 to be installed. We judge that there is much frost. The refrigeration cycle device 1 performs the defrosting operation based on the determination of the control device 100.

Defrosting operation is performed, for example, by the reverse circuit method. In the reverse circuit system, the defrosting operation is performed by switching the four-way valve 7 from the heating operation position to the cooling operation position. In the reverse circuit system, the refrigerant flow direction, gas-liquid phase change, and heat transfer mode are the same in the defrosting operation and the cooling operation. By supplying high-temperature and high-pressure vapor refrigerant to the outdoor heat exchanger 10, the frost attached to the outdoor heat exchanger 10 can be melted. At this time, it is desirable to stop the outdoor fan 6 during the defrosting operation so that the amount of heat of the outdoor heat exchanger 10 does not escape to the outside air. A low-temperature low-pressure gas-liquid two-phase refrigerant flows through the indoor heat exchanger 3. It is desirable to stop the indoor fan 4 during the defrosting operation in order to prevent the cold air from blowing into the indoor space.

During the defrosting operation, when the pipe temperature measured by the outdoor heat exchanger 10 is equal to or higher than a certain value, or when the defrosting operation is continued for a certain time or longer, the control device 100 controls the outdoor heat exchange. It is determined that the defrosting of the container 10 has been completed. In the refrigeration cycle device 1, the four-way valve 7 is switched to the heating operation position based on the determination of the control device 100, and the heating operation is restarted.

Next, control of the refrigeration cycle apparatus 1 by the control device 100 when frost adheres to the outdoor heat exchanger 10 will be described with reference to FIGS. 6 and 7.

FIG. 6 is a control time chart of the refrigeration cycle device 1 according to the present embodiment. FIG. 6A shows the relationship between each operation and the compressor frequency. FIG. 6B shows the relationship between each operation and the normal rotation and the reverse rotation of the outdoor fan. FIG. 6C shows the relationship between each operation and opening/closing (ON-OFF) of the four-way valve. Further, in FIG. 6, times t1 to t5 indicate times when each operation is switched. The subsequent control time chart is the same as in FIG. FIG. 7 is a control flowchart of the refrigeration cycle device 1 according to the present embodiment. Note that these flowcharts are repeatedly executed periodically during the heating operation.

The heating operation is performed when the control device 100 requests the heating operation. If the outdoor air condition is low, frost may adhere to the outdoor heat exchanger 10 during the heating operation. Here, the heating operation in a state where frost adheres to the outdoor heat exchanger 10 is defined as a frost operation (frosting operation).

When the frosting operation is performed for a certain period of time, the outdoor heat exchanger 10 is blocked by frost, and the heat exchange amount decreases. Therefore, the control device 100 temporarily switches from the heating operation to the defrost operation (defrosting operation). At this time, the operation when switching from the frosting operation to the defrosting operation is defined as the frost defrost switching operation (FD operation).

Defrosting operation is performed after FD operation. Generally, while the defrosting operation is being performed, the heat exchanger stops functioning as an evaporator, so the heating operation is also stopped. When the defrosting operation is completed, the control device 100 switches to the frosting operation again. At this time, the operation when switching from the defrosting operation to the frosting operation is defined as a defrost frost switching operation (DF operation).

Hereinafter, the details of the frosting operation, the FD operation, the defrosting operation, and the DF operation will be described in detail.
(Frosting operation)
As described above, when the outdoor air condition is low during the heating operation, frost adheres to the outdoor heat exchanger 10 during the heating operation. When the frosting operation is started (S10) and is performed for a certain period of time, the outdoor heat exchanger 10 is blocked by frost, and the amount of heat exchange is reduced. Here, it is determined whether to start the defrosting operation (S11). When the detected temperature of the temperature sensor 8 (the liquid pipe temperature of the outdoor heat exchanger 10) becomes lower than the threshold temperature, the control device 100 uses the frost so that the amount of heat exchange in the outdoor heat exchanger 10 decreases. It is determined that blockage has occurred.

When the outdoor heat exchanger 10 is not blocked by frost to the extent that the heat exchange amount decreases (NO in S11), the control device 100 ends the process. As a result, the frosting operation is continued. When the outdoor heat exchanger 10 is blocked by frost to the extent that the heat exchange amount decreases (YES in S11), the FD operation in which the frosting operation is switched to the defrosting operation is performed (S20). In the FD operation, the outdoor fan rotation speed (N) decreases to zero. In the FD operation, the compressor frequency (CompHz) decreases to the defrosting operation start frequency (defrosting operation start Hz). The defrosting operation start frequency is, for example, a frequency at which the four-way valve 7 can be switched.

(FD operation)
Then, the control device 100 determines whether or not to shift to the defrosting operation (S21). Here, for example, a case where a reverse circuit system by operation in a refrigerant circuit under cooling conditions is adopted as a defrosting system will be described. In the reverse circuit system, since the outdoor heat exchanger acts as a condenser, the high-temperature and high-pressure refrigerant flows into the heat transfer tube of the heat exchanger and provides a heat quantity for melting frost from the inside of the heat transfer tube. At this time, if the outdoor fan rotation speed is maintained in the same state as during the frosting operation, the heat of the refrigerant is taken away by the low-temperature air flowing outside the heat transfer tubes of the heat exchanger to sufficiently melt the frost. You may not be able to. Therefore, the outdoor fan rotation speed is set to 0 and the defrosting operation is performed. Although this description is an example, it is necessary to change the behavior of the actuator when shifting from the frosting operation to the defrosting operation in this way, and a certain time is required for that purpose. The operation within this time is defined as the FD operation. As an example of another actuator behavior during FD operation, opening/closing of the four-way valve may be switched when switching to the reverse circuit system. At this time, if the pressure difference between the refrigerants is large, it is difficult to switch the opening/closing of the four-way valve, so control is performed to reduce the compressor frequency to the defrosting operation start frequency (defrosting operation start Hz).

For example, when the compressor frequency exceeds the defrosting operation start frequency (NO in S21), the control device 100 returns the process to S20. As a result, the FD operation is continued. When the compressor frequency is equal to or lower than the defrosting operation start frequency (YES in S21), the FD operation shifts to the defrosting operation (S30).

(Defrosting operation)
In the defrosting operation, the amount of heat is provided to the outdoor heat exchanger 10 that has been frosted by, for example, a reverse circuit method. In the defrosting operation, the four-way valve 7 is in the same state as the cooling cycle state. Then, it is determined whether the defrosting by the defrosting operation is completed (S31). Here, for example, when the temperature detected by the temperature sensor 8 (the liquid pipe temperature of the outdoor heat exchanger 10) becomes equal to or higher than the threshold temperature, the control device 100 melts the frost adhering to the outdoor heat exchanger 10. Is determined to have been completed.

When the defrosting of the outdoor heat exchanger 10 by the defrosting operation is not completed (NO in S31), the control device 100 returns the process to S30. As a result, the defrosting operation is continued. When the defrosting of the outdoor heat exchanger 10 by the defrosting operation is completed (YES in S31), the DF operation for switching from the defrosting operation to the frosting operation is performed (S40).

(DF operation)
Here, as an example of the DF operation for switching from the defrosting operation to the frosting operation, a case where a reverse circuit system is adopted as in the FD operation will be described. In order to switch the four-way valve 7 again, control for reducing the compressor frequency to the frosting operation start frequency is performed (S40). Here, before the compressor frequency drops to the frosting operation start frequency, control is performed to rotate the outdoor fan 6 in the opposite direction to that during heating operation (S41).

Next, it is determined whether or not to continue the DF operation (S42). When the compressor frequency exceeds the frosting operation start frequency (NO in S42), control device 100 returns the process to S40. As a result, the DF operation is continued. When the compressor frequency is equal to or lower than the frosting operation start frequency (YES in S42), the DF operation shifts to the frosting operation (S50).

When the frosting operation starts, the four-way valve 7 will be in the same state as the heating cycle state. The compressor frequency increases. The outdoor fan rotation speed is changed to normal rotation. In this way, the operation returns to the start state (S60).

Next, the operation and effect of the refrigeration cycle apparatus 1 according to this embodiment will be described in comparison with a comparative example.

Referring to FIGS. 8 and 9, the refrigeration cycle apparatus of the comparative example is different from refrigeration cycle apparatus 1 according to the present embodiment in that the outdoor fan is not changed to reverse rotation. In the refrigeration cycle device of the comparative example, the water droplets generated in the defrosting operation, when the frosting operation is started again, move backward in the air blowing direction along the surface of the flat heat transfer tube, and the flat heat transfer tube Stay at the top or bottom. Therefore, the water generated in the defrosting operation is not properly discharged. Therefore, the drainage performance cannot be improved.

According to the refrigeration cycle apparatus 1 according to the present embodiment, the fin 30 includes the second region 30b protruding from the heat transfer tube 20 in the direction opposite to the air blowing direction in the heating operation. Therefore, it is possible to suppress the formation of frost on the second region 30b by making the temperature of the second region 30b higher than the temperature of the first region 30a. Therefore, it is possible to suppress the formation of frost on the portion of the outdoor heat exchanger 10 that functions as an evaporator on the windward side in the air blowing direction during the heating operation. Further, the outdoor fan 6 is configured to blow air from the first area 30a to the second area 30b after the defrosting operation is performed. Therefore, the water droplets generated in the defrosting operation can be pushed out to the second region 30b. Therefore, since the water droplets generated in the defrosting operation are discharged along the second region 30b, the water droplets generated in the defrosting operation can be appropriately discharged.

Further, in the refrigeration cycle apparatus 1 according to the present embodiment, control is performed to reversely rotate the outdoor fan 6 in the DF operation, so drainage is performed in a state in which the heating capacity with the reduced compressor frequency is difficult to be exerted. Therefore, the heating operation can be performed in a state where the compressor frequency is increased and the heating capacity is sufficiently exhibited. Therefore, it is possible to improve the total heating capacity in all operating states.

Moreover, when the water retained in the heat transfer tube 20 in the third region 30c is configured not to be discharged through the third region 30c during the heating operation, the width of the third region 30c is larger than the width of the second region 30b. Since it is small, it becomes easy to flow the water droplets generated in the defrosting operation to the second region 30b.

Embodiment 2.
A refrigeration cycle apparatus 1 according to Embodiment 2 of the present invention will be described with reference to FIG. 10. The refrigeration cycle apparatus 1 according to Embodiments 2 to 5 of the present invention has the same configuration, operation, and effect as those of the refrigeration cycle apparatus 1 according to Embodiment 1 of the present invention described above, unless otherwise specified. ing.

As shown in FIG. 10, in the refrigeration cycle device 1 according to the present embodiment, the reverse rotation of the outdoor fan 6 is started during the DF operation and continued until the compressor frequency reaches the target value. This target value is the compressor frequency when the heating capacity is sufficiently exerted. This target value is, for example, a predetermined frequency equal to or lower than the maximum frequency of the compressor 2. The outdoor fan 6 blows air from the first region 30a to the second region 30b until the frequency of the compressor 2 reaches the target value after the heating operation is started again after the defrosting operation is performed. It is configured.

According to the refrigeration cycle apparatus 1 according to the present embodiment, the outdoor fan 6 changes from the first region 30a to the second region 30b until the frequency of the compressor 2 reaches the target value after the heating operation is started again. It is configured to blow air toward. From the time when the heating operation is started again until the frequency of the compressor 2 reaches the target value, since the heating capacity is small, the change in the blowing direction of the outdoor fan 6 is unlikely to affect the heating capacity. Therefore, it is possible to suppress the influence on the heating capacity due to the change in the blowing direction of the outdoor fan 6.

Embodiment 3.
A refrigeration cycle apparatus 1 according to Embodiment 3 of the present invention will be described with reference to FIG. As shown in FIG. 11, in the refrigeration cycle device 1 according to the present embodiment, the reverse rotation of the outdoor fan 6 starts during the DF operation and shifts to the normal rotation during the DF operation. The outdoor fan 6 is configured to blow air from the second area 30b to the first area 30a before the heating operation is started again after the defrosting operation is performed.

According to the refrigeration cycle apparatus 1 according to the present embodiment, the outdoor fan 6 is configured to blow air from the second area 30b toward the first area 30a before the heating operation is started again. Therefore, it is possible to suppress frost formation on the outdoor heat exchanger on the leeward side in the blowing direction during the heating operation. That is, if the outdoor fan 6 blows air from the first area 30a toward the second area 30b when the heating operation is started again, the first area arranged on the leeward side in the air blowing direction during the heating operation. Frost is formed on 30a. According to the refrigeration cycle apparatus 1 according to the present embodiment, the outdoor fan 6 blows air from the second region 30b toward the first region 30a before the heating operation is started again, so that the outdoor fan 6 is blown to the first region 30a. It is possible to suppress the formation of frost.

Fourth Embodiment
A refrigeration cycle apparatus 1 according to Embodiment 4 of the present invention will be described with reference to FIG. As shown in FIG. 12, in the refrigeration cycle apparatus 1 according to the present embodiment, the reverse rotation of the outdoor fan 6 is started during the DF operation, and the compressor frequency becomes equal to or lower than the frosting operation start frequency during the DF operation. It will continue even after it becomes. The outdoor fan 6 is directed from the first region 30a to the second region 30b while the state where the frequency of the compressor 2 is equal to or lower than the value when the heating operation is started again (frosting operation start frequency) continues. It is configured to blow air.

According to the refrigeration cycle apparatus 1 according to the present embodiment, the outdoor fan 6 keeps the first region 30a while the frequency of the compressor 2 remains below the value when the heating operation is started again. To the second region 30b. Therefore, when the frequency of the compressor 2 reaches the value at which the heating operation is started again, the outdoor fan 6 does not immediately change to the normal rotation but continues to rotate in the reverse direction. When the amount of residual water accumulated in the outdoor heat exchanger 10 is large, the outdoor fan 6 continues to rotate in the reverse direction, so that more residual water can be discharged. By making the shortening time of the defrosting operation longer than the increasing time of the DF operation, it becomes possible to reduce the total non-frosting operation time.

Embodiment 5.
13 and 14, refrigeration cycle apparatus 1 according to Embodiment 5 of the present invention is a refrigeration cycle apparatus according to Embodiment 1 in that heat transfer pipe 20 of outdoor heat exchanger 10 is inclined. Different from device 1. As shown in FIGS. 13 and 14, in the refrigeration cycle apparatus 1 according to the present embodiment, the first end portion 20a of the heat transfer tube 20 of the outdoor heat exchanger 10 has a gravity direction G greater than that of the second end portion 20b. It is located below. That is, the heat transfer tube 20 is inclined downward in the gravity direction G from the first region 30a to the second region 30b.

According to the refrigeration cycle apparatus 1 according to the present embodiment, since the heat transfer tube 20 is inclined toward the second region 30b side, drainage is promoted as compared with the case where the heat transfer tube 20 is horizontally arranged. You can Further, since water drops collect at the lower end of the heat transfer tube 20, the collected water drops can be blown. Therefore, it becomes easy to discharge the water droplets.

Sixth embodiment.
Referring to FIG. 15, refrigeration cycle apparatus 1 according to Embodiment 6 of the present invention differs from refrigeration cycle apparatus 1 according to Embodiment 1 in that a refrigeration cycle apparatus 1 is provided with a hot gas circuit. As shown in FIG. 15, the refrigeration cycle device 1 according to the present embodiment includes a hot gas circuit 40.

In the refrigeration cycle apparatus 1 according to this embodiment, the defrosting operation is performed by the hot gas circuit system. In the hot gas circuit system, a high-temperature and high-pressure gas refrigerant (hot gas) is sent to the outdoor heat exchanger 10 during defrosting operation. In the refrigeration cycle apparatus 1 according to the present embodiment, the valve 41 provided in the hot gas circuit 40 is closed during the heating operation and the cooling operation, and the valve 41 is opened during the defrosting operation. As a result, during the defrosting operation, the frost that has frosted on the outdoor heat exchanger 10 is melted by the hot gas that has flowed into the outdoor heat exchanger 10 through the hot gas circuit 40.

The above embodiments can be combined as appropriate.
The embodiments disclosed this time are to be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above description but by the scope of the claims, and is intended to include meanings equivalent to the scope of the claims and all modifications within the scope.

1 refrigeration cycle device, 2 compressor, 3 indoor heat exchanger, 4 indoor fan, 5 decompression device, 6 outdoor fan, 7 four-way valve, 8 temperature sensor, 10 outdoor heat exchanger, 20 heat transfer tube, 20a first end , 20b second end, 30 fins, 30a first area, 30b second area, 30c third area, 31 first edge, 32 second edge, 40 hot gas circuit, 100 controller.

Claims (4)

A compressor for compressing the refrigerant,
A condenser that condenses the refrigerant compressed by the compressor;
A decompression device for decompressing the refrigerant condensed by the condenser,
An evaporator that evaporates the refrigerant decompressed by the decompression device,
A blower fan for blowing air to the evaporator,
The evaporator includes a fin and a heat transfer tube that is inserted into the fin and has a flat cross section.
The fin includes a first region in which the heat transfer tube is inserted, and a second region protruding from the heat transfer tube in a direction opposite to a blowing direction in heating operation,
The blower fan blows air from the second region toward the first region in the heating operation, and after the defrosting operation of melting the frost frosted on the evaporator in the heating operation is performed, the first A refrigeration cycle device configured to blow air from a region toward the second region. The blower fan is configured to blow air from the first region to the second region until the frequency of the compressor reaches a target value after the heating operation is started again. The refrigeration cycle apparatus according to 1. The refrigeration cycle apparatus according to claim 1, wherein the blower fan is configured to blow air from the second region toward the first region before the heating operation is started again. The blower fan is configured to blow air from the first region to the second region while a state in which the frequency of the compressor is equal to or lower than the value when the heating operation is started again continues. The refrigeration cycle apparatus according to claim 1, which is provided.

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