WO2016046927A1

WO2016046927A1 - Refrigeration cycle device and air-conditioning device

Info

Publication number: WO2016046927A1
Application number: PCT/JP2014/075374
Authority: WO
Inventors: 永登齋藤
Original assignee: 三菱電機株式会社
Priority date: 2014-09-25
Filing date: 2014-09-25
Publication date: 2016-03-31
Also published as: GB2545112A; GB201701195D0; GB2545112B

Abstract

A refrigeration cycle device provided with a refrigerant circuit that is provided with a compressor, indoor heat exchanger, throttle device, and outdoor heat exchanger which are connected by refrigerant piping. The refrigeration cycle device is provided with a control device that controls the execution of defrost operation on the basis of the temperature of the outdoor heat exchanger and outside air temperature. The outdoor heat exchanger is provided with at least a first heat exchanger and a second heat exchanger disposed below the first heat exchanger. The control device is configured so as to perform on-defrost operation in which one of the first heat exchanger and the second heat exchanger serves as an evaporator and the hot gas discharged from the compressor is supplied to the other heat exchanger, without passing through the indoor heat exchanger, if the outside air temperature satisfies a preset condition, and to perform reverse defrost operation in which the refrigerant after passing through the indoor heat exchanger is supplied from the compressor to the first heat exchanger and the second heat exchanger if the temperature of the outdoor heat exchanger satisfies a preset condition after the execution of the on-defrost operation.

Description

Refrigeration cycle apparatus and air conditioner

The present invention relates to a refrigeration cycle apparatus and an air conditioner.

The refrigeration cycle apparatus has, for example, a compressor, a four-way valve, an outdoor heat exchanger, a throttling device, and an indoor heat exchanger, and has a refrigerant circuit configured by connecting these with refrigerant piping. Further, for example, the compressor and the outdoor heat exchanger are mounted on an outdoor unit installed outside the room. Here, when the heating operation is performed in the refrigeration cycle apparatus, the outdoor heat exchanger functions as an evaporator.

In the heating operation of the refrigeration cycle apparatus, the outdoor heat exchanger functions as an evaporator, and frost may adhere to the outdoor heat exchanger because it is performed in winter. When frost adheres to the outdoor heat exchanger in this way, the heat exchange efficiency between the refrigerant supplied to the heat transfer tubes of the outdoor heat exchanger and the air passing through the fins connected to the heat transfer tubes is reduced, and the refrigeration cycle The efficiency at the time of heating operation of an apparatus will reduce.

Therefore, in the refrigeration cycle apparatus, in order to melt frost attached to the outdoor heat exchanger, the heating operation is stopped, the flow path of the four-way valve is switched to the cooling operation side, and the outdoor heat exchanger is switched to the outdoor heat exchanger via the indoor heat exchanger. Some carry out reverse defrost operation to supply refrigerant.

Also, a refrigeration cycle apparatus has been proposed in which an outdoor heat exchanger is divided into upper and lower stages (see, for example, Patent Document 1). In the refrigeration cycle apparatus of Patent Document 1, hot gas is supplied to the upper or lower outdoor heat exchanger for defrosting, and the lower or upper outdoor heat exchanger functions as an evaporator to perform heating operation. It is possible to carry out on-defrost operation. When the on-defrost operation is performed, the heating operation can be continued while the defrosting operation is performed on the upper or lower outdoor heat exchanger.

JP 2009-085484 A

The on-defrost operation is an operation that does not use, for example, heat collection from the indoor unit, and raises the temperature of the refrigerant with the compressor and supplies the refrigerant with the raised temperature to the outdoor heat exchanger. In the on-defrost operation performed by the refrigeration cycle apparatus described in Patent Document 1, the defrosting capability is insufficient, and frost may remain in the outdoor heat exchanger after the on-defrost operation is performed.

That is, in the refrigeration cycle apparatus described in Patent Literature 1, when the heating operation is performed after the on-defrost operation is finished, the efficiency of the heating operation is reduced due to frost (residual frost) formed in the outdoor heat exchanger. There is a problem.

The present invention has been made in order to solve the above-described problems, and a refrigeration cycle apparatus and an air conditioner that can suppress a reduction in efficiency of heating operation after finishing on-defrost operation. The purpose is to provide.

A refrigeration cycle apparatus according to the present invention includes a compressor, an indoor heat exchanger, a throttling device, and an outdoor heat exchanger, and in the refrigeration cycle apparatus including a refrigerant circuit in which these are connected by a refrigerant pipe, the outdoor heat exchanger A control device that controls the execution of the defrost operation based on the temperature and the outside air temperature, and the outdoor heat exchanger is a second heat exchanger disposed below the first heat exchanger and the first heat exchanger. When the outside air temperature satisfies a preset condition, the control device causes one of the first heat exchanger and the second heat exchanger to function as an evaporator, On the other hand, the on-defrost operation for supplying hot gas discharged from the compressor without passing through the indoor heat exchanger is performed, and after the on-defrost operation is performed, the temperature of the outdoor heat exchanger satisfies a preset condition. In the room Are those configured to implement the reverse defrosting operation for supplying the refrigerant passing through the exchanger from the compressor to the first heat exchanger and the second heat exchanger.

Since the refrigeration cycle apparatus according to the present invention has the above-described configuration, it is possible to suppress a reduction in the efficiency of the heating operation after the on-defrost operation is finished.

It is a figure showing typically about a refrigerant circuit composition etc. of refrigeration cycle device 500 concerning an embodiment of the invention. It is a schematic diagram of the outdoor heat exchanger 103. It is a figure which shows the flow of the refrigerant | coolant at the time of the heating operation of the refrigerating-cycle apparatus 500 which concerns on embodiment of this invention. It is a figure which shows the flow of the refrigerant | coolant at the time of the cooling operation of the refrigerating-cycle apparatus 500 which concerns on embodiment of this invention. It is a figure which shows a mode that the on-defrost driving | operation of the refrigerating-cycle apparatus 500 which concerns on embodiment of this invention is implemented, and a refrigerant | coolant is supplied to the 1st heat exchanger 103a. It is a figure which shows a mode that the on-defrost driving | operation of the refrigerating-cycle apparatus 500 which concerns on embodiment of this invention is implemented, and a refrigerant | coolant is supplied to the 2nd heat exchanger 103b. It is a figure which shows the flow of the refrigerant | coolant at the time of the reverse defrost driving | operation of the refrigerating-cycle apparatus 500 which concerns on embodiment of this invention. It is a schematic diagram which shows a mode that the frost adhering to the outdoor heat exchanger 103 melts | dissolves when on-defrost operation is implemented. Although the on-defrost operation was carried out, it was frozen in the second heat exchanger 103b, and frost could not be removed, so that the reverse defrost operation was performed. Although the on-defrost operation was carried out, the frost formation amount of the first heat exchanger 103a and the second heat exchanger 103b was large, and the frost could not be removed in either case, so that the reverse defrost operation was performed. It is. It is a schematic diagram showing a state where reverse defrost operation is performed without performing on-defrost operation because the amount of frost formation on the first heat exchanger 103a and the second heat exchanger 103b is large. It is a control flowchart at the time of transfer from the heating operation of the refrigeration cycle apparatus 500 which concerns on embodiment of this invention to a defrost operation. It is the modification 1 of the outdoor heat exchanger 103 of the refrigerating-cycle apparatus 500 which concerns on embodiment of this invention. It is the modification 2 of the outdoor heat exchanger 103 of the refrigerating-cycle apparatus 500 which concerns on embodiment of this invention. It is the modification 3 of the outdoor heat exchanger 103 of the refrigerating-cycle apparatus 500 which concerns on embodiment of this invention. It is the modification 4 of the outdoor heat exchanger 103 of the refrigerating-cycle apparatus 500 which concerns on embodiment of this invention. It is the modification 5 of the outdoor heat exchanger 103 of the refrigerating-cycle apparatus 500 which concerns on embodiment of this invention.

Hereinafter, embodiments of a refrigeration cycle apparatus and an air conditioner according to the present invention will be described with reference to the drawings. The present invention is not limited to the embodiments described below. Moreover, in the following drawings including FIG. 1, the relationship of the size of each component may be different from the actual one.

Embodiment.
FIG. 1 is a diagram schematically showing a refrigerant circuit configuration and the like of a refrigeration cycle apparatus 500 according to the present embodiment. FIG. 2 is a schematic diagram of the outdoor heat exchanger 103. A refrigerant circuit configuration and the like of the refrigeration cycle apparatus 500 will be described with reference to FIG. In the present embodiment, a case where refrigeration cycle apparatus 500 is an air conditioner will be described as an example.
The refrigeration cycle apparatus 500 according to the present embodiment is provided with an improvement in which on-defrost operation and reverse defrost operation are performed based on the outside air temperature and the temperature of the outdoor heat exchanger 103.

[Outdoor unit 100]
The outdoor unit 100 is a heat source device that supplies cold heat or warm heat to the indoor unit 300. The outdoor unit 100 includes a compressor 101 that compresses and discharges the refrigerant, a four-way switching valve 102 that is used to switch between cooling operation and heating operation, and functions as a condenser during cooling operation, and evaporates during heating operation. An outdoor heat exchanger 103 that functions as a storage unit and an accumulator 104 that is used to store surplus refrigerant in the refrigerant circuit C are connected by refrigerant piping and mounted.

Further, the outdoor unit 100 is equipped with a switching valve 105a, a switching valve 105b, a switching valve 106a, and a switching valve 106b that are used for switching between a cooling operation, a heating operation, a reverse defrost operation, an on-defrost operation, and the like. . The outdoor unit 100 is provided with an outdoor fan 109 that is attached to the outdoor heat exchanger 103 and supplies air to the outdoor heat exchanger 103.

Furthermore, the outdoor unit 100 is equipped with a control device 119 for controlling the rotational speed of the compressor 101 and the like when performing cooling operation, heating operation, reverse defrost operation, on-defrost operation, and the like. The outdoor unit 100 includes an outdoor air temperature sensor 153, a refrigerant temperature detection unit 151, a high pressure sensor 141, and a low pressure sensor 142 that are used when the control device 119 determines switching between heating operation, reverse defrost operation, and on defrost operation. have.

Here, on-defrost operation and reverse defrost operation will be described. The on-defrost operation does not use the indoor unit 300 as a heat collection source. That is, in the on-defrost operation, the defrosting capability is lower than that in the reverse defrost operation because the indoor unit 300 is not used as a heat collection source. On the other hand, in the on-defrost operation, any one of the heat exchangers constituting the outdoor heat exchanger 103, that is, one of the first heat exchanger 103a and the second heat exchanger 103b described later is used. The heating operation can be continued by functioning as an evaporator. In the on-defrost operation, hot gas refrigerant discharged from the compressor 101 is supplied to the outdoor heat exchanger 103 by bypassing the indoor heat exchanger 312.

Further, since the reverse defrost operation is an operation that uses the indoor unit 300 as a heat collection source and uses the latent heat of the refrigerant, the defrosting capability is higher than the on-defrost operation that supplies hot gas to the outdoor heat exchanger 103. For this reason, the defrosting of the outdoor heat exchanger 103 can be completed in a shorter time than the on-defrost operation. In the reverse defrost operation, the four-way switching valve 102 is switched to the cooling side so that the refrigerant flow is reversed from that in the heating operation.

(Compressor 101)
The compressor 101 sucks low-temperature and low-pressure gas refrigerant, compresses the refrigerant into high-temperature and high-pressure gas refrigerant, and circulates the refrigerant in the refrigerant circuit C. The compressor 101 may be composed of an inverter type compressor whose capacity can be controlled, for example. However, the compressor 101 is not limited to an inverter type compressor that can control the capacity, but may be a constant speed type compressor, or a compressor that combines an inverter type and a constant speed type. The compressor 101 has a discharge side connected to the four-way switching valve 102 and a suction side connected to the accumulator 104.

The compressor 101 is not particularly limited as long as it can compress the sucked refrigerant. For example, the compressor 101 can be configured using various types such as reciprocating, rotary, scroll, or screw.

(Four-way switching valve 102)
The four-way switching valve 102 is provided on the discharge side of the compressor 101 and switches the refrigerant flow path between the cooling operation and the heating operation. That is, the four-way switching valve 102 controls the flow of the refrigerant so that the outdoor heat exchanger 103 functions as an evaporator or a condenser according to the operation mode. The four-way switching valve 102 is switched so as to connect the indoor heat exchanger 312 and the compressor 101 and to connect the outdoor heat exchanger 103 and the accumulator 104 during the heating operation. In addition, the four-way switching valve 102 is switched so as to connect the outdoor heat exchanger 103 and the compressor 101 and to connect the indoor heat exchanger 312 and the accumulator 104 during the cooling operation.

(Outdoor heat exchanger 103)
The outdoor heat exchanger 103 exchanges heat between a heat medium (for example, ambient air, water, etc.) and a refrigerant, evaporates and gasifies the refrigerant as an evaporator during heating operation, and a condenser (heat radiator) during cooling operation. ) To condense and liquefy the refrigerant. The outdoor heat exchanger 103 can be configured by, for example, a fin tube heat exchanger having a heat transfer tube through which a refrigerant flows and a plurality of fins connected to the heat transfer tube. The outdoor heat exchanger 103 has its condensation capacity or evaporation capacity controlled by the rotational speed of the outdoor fan 109. The outdoor heat exchanger 103 includes a plurality of heat exchangers. That is, the outdoor heat exchanger 103 includes a first heat exchanger 103a and a second heat exchanger 103b disposed below the first heat exchanger 103a.

One side of the first heat exchanger 103a is connected to the four-way switching valve 102, and the other side is connected to the expansion device 311 via the switching valve 105a. One of the second heat exchangers 103b is connected to the four-way switching valve 102, and the other is connected to the expansion device 311 via the switching valve 105b. In the present embodiment, as shown in FIG. 2, a mode in which the first heat exchanger 103a is installed on the second heat exchanger 103b will be described, but the present invention is not limited to this. The heat exchanger 103b and the first heat exchanger 103a may be separated from each other.

(Accumulator 104)
The accumulator 104 is provided on the suction side of the compressor 101, and has a function of storing surplus refrigerant and a function of separating liquid refrigerant and gas refrigerant. One of the accumulators 104 is connected to the suction side of the compressor 101 and the other is connected to the four-way switching valve 102.

(Control device 119)
The control device 119 executes various operations such as a cooling operation, a heating operation, a reverse defrost operation, and an on-defrost operation based on detection results of the outside air temperature sensor 153, the refrigerant temperature detection unit 151, the high pressure sensor 141, and the low pressure sensor 142. Is to control. In order to perform these various operations, the control device 119 performs the rotation speeds (including operation and stop) of the indoor fan 313 and the outdoor fan 109, the rotation speed (including operation and stop) of the compressor 101, and the four-way switching valve. 102, the switching valve 105a, the switching valve 105b, the switching valve 106a and the switching valve 106b, and the opening degree of the expansion device 311 are controlled.

FIG. 1 shows an example in which a control device 119 that controls the operation of the refrigeration cycle apparatus 500 is mounted in the outdoor unit 100, but it may be provided in the indoor unit 300. Further, the control device 119 may be provided outside the outdoor unit 100 and the indoor unit 300. Further, the control device 119 may be divided into a plurality according to the function and provided in each of the outdoor unit 100 and the indoor unit 300. In this case, each control device may be connected wirelessly or by wire.

In the control device 119, the detection result of the first refrigerant temperature sensor 151a of the refrigerant temperature detection unit 151 described later is equal to or lower than the first refrigerant temperature Ta set in advance, and the detection result of the outside air temperature sensor 153 is preset. When the temperature is higher than the outside air temperature, the on-defrost operation is performed (see step S2 and step S3 in FIG. 8). Further, the control device 119 is configured to perform the reverse defrost operation when the detection result of the second refrigerant temperature sensor 151b of the refrigerant temperature detection unit 151 is equal to or lower than the second refrigerant temperature Tb set in advance. (See step S6 in FIG. 8). As the first refrigerant temperature Ta and the second refrigerant temperature Tb, for example, 2 degrees can be adopted, and as the preset outside air temperature Tair, for example, 1 degree can be adopted. In the present embodiment, the first refrigerant temperature Ta and the second refrigerant temperature Tb are set to values larger than the outside air temperature Tair, for example.

In the present embodiment, the first refrigerant temperature Ta and the second refrigerant temperature Tb are set to the same value, but are not limited thereto. For example, the value of the second refrigerant temperature Tb may be set smaller than the first refrigerant temperature Ta, and the reverse defrost operation may be adjusted so as not to be performed even if some frost remains. Alternatively, the value of the second refrigerant temperature Tb may be set higher than the first refrigerant temperature Ta to facilitate the control to perform the reverse defrost operation, and frost may be more reliably removed.

When performing the on-defrost operation and the reverse defrost operation, the control device 119 may control the rotation speed of the compressor 101 to be, for example, the maximum rotation speed. Thereby, a higher temperature gas refrigerant can be supplied to the outdoor heat exchanger 103, and the defrost of the outdoor heat exchanger 103 can be implemented with high efficiency.

(Various sensors)
The outside air temperature sensor 153 detects the outside air temperature. The outdoor temperature sensor 153 is attached to, for example, a housing portion of the outdoor unit 100. The outside air temperature sensor 153 is used to determine whether to perform on-defrost operation or reverse defrost operation. In the refrigeration cycle apparatus 500, when performing the defrosting operation, the on-defrost operation is performed when the outside air temperature is higher than the preset temperature, and the reverse is performed when the outside air temperature is equal to or lower than the preset temperature. It is configured to perform defrost operation.

The refrigerant temperature detector 151 is attached to the outdoor heat exchanger 103 and is used to detect the temperature of the refrigerant in the outdoor heat exchanger 103. The refrigerant temperature detector 151 is used to determine whether or not to perform on-defrost operation and reverse defrost operation. The refrigerant temperature detector 151 is attached to the first heat exchanger 103a, is attached to the first refrigerant temperature sensor 151a that detects the refrigerant of the first heat exchanger 103a, and the second heat exchanger 103b. And a second refrigerant temperature sensor 151b that detects the refrigerant of the second heat exchanger 103b. The first refrigerant temperature sensor 151a is disposed on the inlet side of the first heat exchanger 103a, that is, at a position where the refrigerant temperature before flowing into the first heat exchanger 103a can be detected. The second refrigerant temperature sensor 151b is disposed at the inlet side of the second heat exchanger 103b, that is, at a position where the refrigerant temperature before flowing into the second heat exchanger 103b can be detected. For example, the first refrigerant temperature sensor 151a is attached to a refrigerant pipe that connects the first heat exchanger 103a and the switching valve 105a, and the second refrigerant temperature sensor 151b is switched to the second heat exchanger 103b. It is attached to a refrigerant pipe connecting the valve 105b.

Here, the arrangement positions of the first refrigerant temperature sensor 151 a and the second refrigerant temperature sensor 151 b are not limited to this, and may be installed, for example, on the outlet side of the outdoor heat exchanger 103.

The high pressure sensor 141 detects the pressure of the refrigerant discharged from the compressor 101. The high-pressure sensor 141 is attached to a refrigerant pipe that connects the discharge side of the compressor 101 and the four-way switching valve 102. In the refrigeration cycle apparatus 500, during the on-defrost operation and the reverse defrost operation, the control device 119 causes the compressor 101 to operate at the maximum rotation speed. For this reason, the refrigerant pressure discharged from the compressor 101 tends to increase. When the refrigerant pressure increases, the refrigerant oil used for lubricating the drive portion of the compressor 101 may deteriorate due to, for example, an increase in the refrigerant temperature accompanying an increase in the refrigerant pressure. Therefore, when the discharge refrigerant pressure is higher than a preset value, the high-pressure sensor 141 causes the control device 119 to reduce the rotation speed of the compressor 101 or stop the compressor 101.

The low pressure sensor 142 detects the pressure of the refrigerant sucked into the compressor 101. The low pressure sensor 142 is attached to a refrigerant pipe that connects the refrigerant inflow side of the accumulator 104 and the four-way switching valve 102. If frost adheres to the outdoor heat exchanger 103 (evaporator) during the heating operation, the fins are clogged, and the heat exchange efficiency between the refrigerant and the air in the outdoor heat exchanger 103 is reduced. Thereby, at the time of heating operation, the refrigerant becomes difficult to gasify in the outdoor heat exchanger 103, and the low pressure may be lowered. The low pressure sensor 142 is used to detect such a low pressure abnormality. In the present embodiment, as an example, when a preset time has elapsed since the heating operation was performed (step S1 in FIG. 8 described later), and the refrigerant temperature and the outside air temperature satisfy the preset conditions, the on-defrost is performed. Although the aspect which implements a driving | operation and a reverse defrost driving | operation is demonstrated, it is not limited to it. For example, the controller 119 may be configured to perform the on-defrost operation and the reverse defrost operation when the detection result of the low-pressure sensor 142 becomes smaller than a preset value during the heating operation.

[Indoor unit 300]
The indoor unit 300 is a load side unit to which cold or warm heat is supplied from the outdoor unit 100. In the indoor unit 300, an indoor heat exchanger 312 and an expansion device 311 are mounted connected in series. A blower (not shown) for supplying air to the indoor heat exchanger 312 may be provided. However, the indoor heat exchanger 312 may perform heat exchange between the refrigerant and a heat medium different from the refrigerant such as water.

(Indoor heat exchanger 312)
The indoor heat exchanger 312 performs heat exchange between a heat medium (for example, ambient air and water) and the refrigerant, condenses and liquefies the refrigerant as a condenser (heat radiator) during heating operation, and evaporates during cooling operation. As a vessel, the refrigerant is evaporated and gasified. Similarly to the outdoor heat exchanger 103, the indoor heat exchanger 312 can be configured by, for example, a fin tube heat exchanger having a heat transfer tube through which a refrigerant flows and a plurality of fins connected to the heat transfer tube. The indoor heat exchanger 312 has its condensation capacity or evaporation capacity controlled by the rotational speed of the indoor fan 313.

(Aperture device 311)
The expansion device 311 decompresses and expands the refrigerant. As the expansion device 311, a device whose opening degree can be variably controlled, for example, an electronic expansion valve can be employed. In addition, the throttle device 311 cannot adjust the opening degree like an electronic expansion valve or the like, but can employ a capillary or the like that is less expensive than an electronic expansion valve.

Furthermore, the refrigeration cycle apparatus 500 can use various refrigerants as the refrigerant sealed in the refrigerant circuit C. For example, natural refrigerants such as carbon dioxide refrigerant, hydrocarbon refrigerant, and helium can be employed. In addition, alternative refrigerants that do not contain chlorine, such as HFC410A refrigerant, HFC407C refrigerant, and HFC404A refrigerant, may be employed. Furthermore, a fluorocarbon refrigerant such as an R22 refrigerant or an R134a refrigerant can also be used.

[About operation of heating operation and cooling operation]
FIG. 3A is a diagram showing a refrigerant flow during heating operation of the refrigeration cycle apparatus 500 according to the present embodiment. FIG. 3B is a diagram showing a refrigerant flow during the cooling operation of the refrigeration cycle apparatus 500 according to the present embodiment. The operation of the refrigeration cycle apparatus 500 during the heating operation and the cooling operation will be described with reference to FIGS. 3A and 3B.

The refrigeration cycle apparatus 500 starts the cooling operation and the heating operation when receiving a signal indicating that the cooling operation is performed, a signal indicating that the heating operation is performed, or the like from a remote controller installed in the room, for example.

During the heating operation, the control device 119 switches the four-way switching valve 102 to the heating side, connects the discharge side of the compressor 101 and the indoor heat exchanger 312, and connects the refrigerant inflow side of the accumulator 104 and the outdoor heat exchanger. 103 is connected. Further, the control device 119 sets the rotation speed of the compressor 101 to a preset rotation speed, sets the rotation speeds of the outdoor fan 109 and the indoor fan 313 to a preset rotation speed, and sets the opening of the expansion device 311 in advance. To the desired opening. Furthermore, the control device 119 opens the switching valve 105a and the switching valve 105b, and closes the switching valve 106a and the switching valve 106b. As shown in FIG. 3A, the refrigerant discharged from the compressor 101 flows into the indoor heat exchanger 312 after flowing through the four-way switching valve 102 and is condensed and liquefied. Thereafter, the refrigerant flowing out of the indoor heat exchanger 312 is decompressed by the expansion device 311 and then gasified by the outdoor heat exchanger 103. The refrigerant that has flowed out of the outdoor heat exchanger 103 flows into the accumulator 104 through the four-way switching valve 102. The gas refrigerant out of the refrigerant in the accumulator 104 flows into the suction side of the compressor 101.

During the cooling operation, the control device 119 switches the four-way switching valve 102 to the cooling side, connects the discharge side of the compressor 101 and the outdoor heat exchanger 103, and connects the refrigerant inflow side of the accumulator 104 and the indoor heat exchanger. 312 is connected. Further, the control device 119 sets the rotation speed of the compressor 101 to a preset rotation speed, sets the rotation speeds of the outdoor fan 109 and the indoor fan 313 to a preset rotation speed, and sets the opening of the expansion device 311 in advance. To the desired opening. Furthermore, the control device 119 opens the switching valve 105a and the switching valve 105b, and closes the switching valve 106a and the switching valve 106b. As shown in FIG. 3B, the refrigerant discharged from the compressor 101 flows into the outdoor heat exchanger 103 after flowing through the four-way switching valve 102, and is condensed and liquefied. Thereafter, the refrigerant flowing out of the outdoor heat exchanger 103 is decompressed by the expansion device 311 and then gasified by the indoor heat exchanger 312. The refrigerant that has flowed out of the indoor heat exchanger 312 flows into the accumulator 104 through the four-way switching valve 102. The gas refrigerant out of the refrigerant in the accumulator 104 flows into the suction side of the compressor 101.

[On defrost operation and reverse defrost operation]
FIG. 4A is a diagram illustrating a state in which the on-defrost operation of the refrigeration cycle apparatus 500 according to the present embodiment is performed and the refrigerant is supplied to the first heat exchanger 103a. FIG. 4B is a diagram illustrating a state in which the on-defrost operation of the refrigeration cycle apparatus 500 according to the present embodiment is performed and the refrigerant is supplied to the second heat exchanger 103b. FIG. 4C is a diagram showing a refrigerant flow during the reverse defrost operation of the refrigeration cycle apparatus 500 according to the present embodiment.

The control device 119 is configured to switch between the first heat exchanger 103a and the second heat exchanger 103b that function as an evaporator and the one that supplies hot gas when performing on-defrost operation. Has been. That is, in the on-defrost operation, the first heat exchanger 103a functions as an evaporator, the first operation mode for supplying hot gas to the second heat exchanger 103b, and the second heat exchanger 103b is evaporated. And a second operation mode for supplying hot gas to the first heat exchanger 103a. 4A corresponds to the explanatory diagram of the first operation mode, and FIG. 4B corresponds to the explanatory diagram of the second operation mode.

(On-defrost operation: 1st operation mode)
As shown in FIG. 4A, in the first operation mode, the control device 119 switches the four-way switching valve 102 to the heating side. In the present embodiment, since the on-defrost operation is performed when the heating operation is performed, the four-way switching valve 102 remains on the heating side. For this reason, the control device 119 does not switch the four-way switching valve 102. In addition, the control device 119 maximizes the rotation speed of the compressor 101 and sets the rotation speeds of the outdoor fan 109 and the indoor fan 313 to preset rotation speeds. During the on-defrost operation, the outdoor fan 109 and the indoor fan 313 are operated to continue the heating operation. The control device 119 sets the opening degree of the expansion device 311 to a preset opening degree. Further, the control device 119 opens the switching valve 105a and closes the switching valve 105b. The control device 119 closes the switching valve 106a and opens the switching valve 106b. Thus, the first heat exchanger 103a functions as an evaporator, and hot gas refrigerant discharged from the compressor 101 is supplied to the second heat exchanger 103b (FIGS. 5A and 5B). ), FIG. 6 (a) and FIG. 6 (b)).

As shown in FIG. 4A, a part of the refrigerant discharged from the compressor 101 flows into the indoor heat exchanger 312 after flowing through the four-way switching valve 102, and is condensed and liquefied. The other part of the refrigerant discharged from the compressor 101 flows through the switching valve 106b and then flows into the second heat exchanger 103b to melt frost. The refrigerant flowing out from the indoor heat exchanger 312 is decompressed by the expansion device 311 and then gasified by the first heat exchanger 103a.

As shown in FIG. 4A, the refrigerant flowing out from the first heat exchanger 103a and the refrigerant flowing out from the second heat exchanger 103b merge on the downstream side of the outdoor heat exchanger 103, and then the four-way switching valve 102 is To the accumulator 104. The gas refrigerant out of the refrigerant in the accumulator 104 flows into the suction side of the compressor 101.

(On-defrost operation: second operation mode)
As shown in FIG. 4B, in the second operation mode, the control device 119 closes the switching valve 105a and opens the switching valve 105b. Further, the control device 119 opens the switching valve 106a and closes the switching valve 106b. The control of the other configuration is the same as in the first operation mode. Accordingly, the second heat exchanger 103b functions as an evaporator, and hot gas refrigerant discharged from the compressor 101 is supplied to the first heat exchanger 103a (FIGS. 5C and 5D). ), FIG. 6 (c) and FIG. 6 (d)).

As shown in FIG. 4B, in this second operation mode, a part of the refrigerant discharged from the compressor 101 flows into the indoor heat exchanger 312 after flowing through the four-way switching valve 102 and is condensed and liquefied. . The refrigerant flowing out of the indoor heat exchanger 312 is decompressed by the expansion device 311 and then gasified by the second heat exchanger 103b. Moreover, after the other part of the refrigerant | coolant discharged from the compressor 101 flows through the switching valve 106b, it flows in into the 1st heat exchanger 103a, and melts frost.

The control device 119 executes the first operation mode for 10 minutes, for example, and then executes the second operation mode for 10 minutes. In addition, it is not limited to 10 minutes, It may be longer or shorter than this. Further, for example, there are circumstances such as the size of the first heat exchanger 103a and the second heat exchanger 103b differing, and the time required for defrosting is between the first heat exchanger 103a and the second heat exchanger 103b. If they are different, they may be set to different values.

(Reverse defrost operation)
Since the reverse defrost operation is performed after the heating operation or the on-defrost operation is performed, the control device 119 is on the heating side. For this reason, as shown in FIG. 4C, the control device 119 switches the four-way switching valve 102 on the heating side to the cooling side.

The control device 119 maximizes the rotation speed of the compressor 101. In addition, the control device 119 stops the operation of the outdoor fan 109 and the indoor fan 313. If the outdoor fan 109 is operated during the reverse defrost operation, cold outdoor air is supplied to the outdoor heat exchanger 103, and frost is hardly melted. Therefore, the outdoor fan 109 is stopped. In addition, when the indoor fan 313 is operated during the reverse defrost operation, the cold air that has passed through the indoor heat exchanger 312 functioning as an evaporator is supplied to the room in winter and the indoor fan 313 is stopped.

The control device 119 sets the opening degree of the expansion device 311 to a preset opening degree. Further, the control device 119 opens the switching valve 105a and the switching valve 105b, and closes the switching valve 106a and the switching valve 106b. In the reverse defrost operation, the first heat exchanger 103a and the second heat exchanger 103b are caused to function as a condenser, and frost is removed more strongly than in the on-defrost operation (FIGS. 6E and 6F). reference). The control device 119 performs the reverse defrost operation, for example, for 7 to 12 minutes.

The reverse defrost operation is an operation shifted from the heating operation or the on-defrost operation. For this reason, the indoor heat exchanger 312 is a condenser during heating operation or on-defrost operation, and has heat corresponding to that. In the reverse defrost operation, the temperature of the refrigerant flowing out from the indoor heat exchanger 312 is raised through the indoor heat exchanger 312, and the refrigerant whose temperature has been raised is compressed by the compressor 101 and supplied to the outdoor heat exchanger 103. . Thereby, after carrying out the on-defrost operation, the reverse defrost operation is carried out, and even if residual frost is formed in the on-defrost operation, it can be removed (see step S4 and step S7 in FIG. 8 described later). ). Further, reverse defrost operation is performed after the heating operation is performed, and it is possible to avoid that the amount of frost formation is large and the defrost time is too long in the on defrost operation (step S3 and FIG. 8 described later). (See step S7).

The refrigerant that has flowed out and heated from the indoor heat exchanger 312 flows into the suction side of the compressor 101 via the four-way switching valve 102. Then, the refrigerant discharged from the compressor 101 flows into the outdoor heat exchanger 103 after flowing through the four-way switching valve 102, is condensed and liquefied, and melts frost adhering to the outdoor heat exchanger 103. The refrigerant flowing out of the outdoor heat exchanger 103 is decompressed by the expansion device 311 and then flows into the indoor heat exchanger 312.

[How frost melts during on-defrost operation]
FIG. 5 is a schematic diagram showing how the frost F adhering to the outdoor heat exchanger 103 melts when the on-defrost operation is performed. FIG. 5A shows a state in which hot gas is supplied to the first heat exchanger 103a and the second heat exchanger 103b functions as an evaporator, and FIG. The mode that the frost F of the 1st heat exchanger 103a melt | dissolved after the operation | movement of a) is shown. FIG.5 (c) shows a mode that hot gas is supplied to the 2nd heat exchanger 103b, and the 1st heat exchanger 103a is functioning as an evaporator, FIG.5 (d) shows FIG.5 (c). The mode that the frost F of the 2nd heat exchanger 103b melt | dissolved after operation | movement of (2) is shown.

The frost of the upper first heat exchanger 103a melts and flows into the second heat exchanger 103b, and the second heat exchanger 103b has an iced portion FI formed by freezing of water. Here, in FIG. 5, the aspect which can remove the frost F adhering to the outdoor heat exchanger 103 is assumed, without implementing reverse defrost driving | operation. For example, when the amount of frost formation on the outdoor heat exchanger 103 is small, the amount of water that melts in the first heat exchanger 103a and flows into the second heat exchanger 103b is also small. Therefore, since the freezing part FI is also small, the freezing part FI of the outdoor heat exchanger 103 can be removed by the on-defrost operation.

[The frost melts during on-defrost operation and reverse defrost operation]
FIG. 6A is a schematic diagram illustrating a state where reverse defrost operation is performed because on-defrost operation is performed, but frost is not removed due to icing in the second heat exchanger 103b. When the on-defrost operation is performed, the water dissolved by the heat of the upper first heat exchanger 103a flows into the lower second heat exchanger 103b functioning as an evaporator. When melted water flows directly into the second heat exchanger 103b instead of moisture from the air, the fins of the second heat exchanger 103b are frozen and frost formation further proceeds There is. For this reason, even if hot gas is supplied to the 2nd heat exchanger 103b after supplying hot gas to the 1st heat exchanger 103a, it cannot defrost or it takes too much time for defrosting. There is a case.

For example, when hot gas is supplied to the first heat exchanger 103a and the second heat exchanger 103b is functioning as an evaporator, water melted in the first heat exchanger 103a is melted and fins and the like are dissolved. And adheres to the second heat exchanger 103b. Since the second heat exchanger 103b functions as an evaporator, water flowing from the first heat exchanger 103a is frozen by the fins of the second heat exchanger 103b, and frost formation is further formed. May go on.
In view of this, in the refrigeration cycle apparatus 500, it is assumed that frost cannot be removed by on-defrost operation or that it takes too much time for defrosting, and reverse defrost operation can be performed under preset conditions. It is like that.

FIG. 6A (a) shows a state in which hot gas is supplied to the first heat exchanger 103a and the second heat exchanger 103b functions as an evaporator, and FIG. 6A (b) shows FIG. 6A (a). ), The frost of the first heat exchanger 103a is not completely melted. As shown in FIGS. 6A (a) and 6A (b), the frost of the upper first heat exchanger 103a melts and flows into the second heat exchanger 103b, and the second heat exchanger 103b is frozen. Part FI has occurred.

FIG. 6A (c) shows a state in which hot gas is supplied to the second heat exchanger 103b and the first heat exchanger 103a functions as an evaporator, and FIG. 6A (d) shows the state shown in FIG. ), The frost of the second heat exchanger 103b is not completely melted. In other words, the frozen portion FI cannot be removed by the defrosting capability of the hot gas.

FIG. 6E shows a state in which the reverse defrost operation is performed and the refrigerant that has passed through the indoor heat exchanger 312 is supplied to the first heat exchanger 103a and the second heat exchanger 103b. (F) has shown the mode that the frost of the 1st heat exchanger 103a and the 2nd heat exchanger 103b melt | dissolved after the operation | movement of FIG.6 (d). In the reverse defrost operation, the defrosting capability is higher than that in the on defrost operation, so that the icing portion FI can be removed.

In FIG. 6B, the on-defrost operation was performed, but the amount of frost formation in the first heat exchanger 103a and the second heat exchanger 103b was large, and frost could not be removed in either case, so the reverse defrost operation was performed. It is a schematic diagram which shows. FIGS. 6B (a) to 6B (f) correspond to FIGS. 6A (a) to 6 (f), respectively.
As shown in FIG. 6B, when the amount of frost F formed in the outdoor heat exchanger 103 is large, as shown in FIG. 6B (b), some frost can be removed. Most of the frost F may remain. Thus, even if there is much frost adhering to the outdoor heat exchanger 103, frost can be removed by carrying out the reverse defrost operation.

[Frost melting with reverse defrost operation]
FIG. 7 is a schematic diagram showing a state in which the reverse defrost operation is performed without performing the on-defrost operation because the frost formation amount of the first heat exchanger 103a and the second heat exchanger 103b is large. FIG. 7A shows a state in which the reverse defrost operation is performed and the refrigerant that has passed through the indoor heat exchanger 312 is supplied to the first heat exchanger 103a and the second heat exchanger 103b. (B) has shown the mode that the frost of the 1st heat exchanger 103a and the 2nd heat exchanger 103b melt | dissolved after the operation | movement of Fig.7 (a). As shown in FIG. 7, when the amount of frost formation itself is large, the reverse defrost operation is performed without performing the on defrost operation. Thereby, it can avoid that the defrost time will become unnecessarily long. The determination corresponding to the determination of the amount of frost formation is performed in step S3 described later.

[About control flow]
FIG. 8 is a control flowchart when the refrigeration cycle apparatus 500 according to the present embodiment shifts from the heating operation to the defrosting operation (on-defrost operation and reverse defrost operation). A control flow of the refrigeration cycle apparatus 500 will be described with reference to FIG.

(Step S1: Heating operation time determination)
The control device 119 performs the determination on the heating operation time. The heating operation elapsed time t is a value set in advance based on the operation capacity of the outdoor unit 100, the performance of the outdoor heat exchanger 103, and the like. The heating operation elapsed time t is stored in advance in a microcomputer of the control device 119 or the like.

(Step S2: Determination relating to presence or absence of frost formation)
The control device 119 performs determination based on the first refrigerant temperature Ta set in advance and the detection result of the first refrigerant temperature sensor 151a. When the detection result of the first refrigerant temperature sensor 151a is equal to or lower than the first refrigerant temperature Ta (for example, 2 ° C.), the process proceeds to step S3. If the detection result of the first refrigerant temperature sensor 151a is higher than the first refrigerant temperature Ta, the process returns to step S0.

In step S2, a determination is made regarding the presence or absence of frost formation. That is, in this step S2, determination based on the temperature of the refrigerant before flowing into the first heat exchanger 103a is performed, and frost more than a preset amount is formed in the outdoor heat exchanger 103, so that the defrost operation is performed. It is determined whether or not is necessary. In the case where the heating operation is performed, the refrigerant just before being supplied to the outdoor heat exchanger 103 is cooled in the process of passing through the indoor heat exchanger 312 functioning as a condenser. When the cooled refrigerant is supplied to the outdoor heat exchanger 103, the outdoor heat exchanger 103 is likely to form frost. Therefore, when the detection result of the first refrigerant temperature sensor 151a is equal to or lower than the first refrigerant temperature Ta, it is determined that the defrost operation is performed. This defrost operation includes (1) when only on-defrost operation is performed and returning to heating operation, (2) when only reverse defrost operation is performed and returning to heating operation, and (3) on-defrost operation and reverse defrost operation. In some cases, both operations are performed and then the heating operation is returned.

(Step S3: Judgment related to degree of frost formation)
The control device 119 performs a determination on the preset outside air temperature Tair. In this determination, the type of defrost operation to be performed is determined. When the detection result of the outside air temperature sensor 153 is higher than a preset outside air temperature Tair (for example, 1 ° C.), the process proceeds to step S4. If the outside air temperature is not so low, it is assumed that frost formation on the outdoor heat exchanger 103 can be removed even in on-defrost operation. For this reason, it transfers to step S4 from step S3 and implements an on-defrost operation.

When the detection result of the outside air temperature sensor 153 is equal to or lower than the preset outside air temperature Tair, the process proceeds to step S8. When the outside air temperature is low, the degree of frost formation in the outdoor heat exchanger 103 is assumed to be large as described with reference to FIG. For this reason, it is difficult to melt the frost in the on-defrost operation, or it takes a long time to melt the frost, so the process proceeds from step S3 to step S8. That is, in this step S3, the time required for different defrost operations according to the degree of frost formation is determined from the outside air temperature. The value of the outside air temperature Tair can be determined, for example, based on a test result that is performed in advance.

(Step S4 and Step S5: On-defrost operation)
The control device 119 performs on-defrost operation. In other words, the control device 119 performs the second operation mode after performing the first operation mode. When the on-defrost operation ends, the control device 119 proceeds to step S6.

(Step S6: Determination related to presence or absence of residual frost)
The control device 119 performs determination based on the second refrigerant temperature Tb set in advance and the detection result of the second refrigerant temperature sensor 151b. When the detection result of the second refrigerant temperature sensor 151b is equal to or lower than the second refrigerant temperature Tb (for example, 2 ° C.), the process proceeds to step S7. The reason for shifting from step S6 to step S7 is that it is determined that there is residual frost after the on-defrost operation is completed. That is, in this step S6, it is determined using the detection result of the second refrigerant temperature sensor 151b whether or not the frost has been completely melted in the above-described on-defrost operation of step S4. If the detection result of the second refrigerant temperature sensor 151b is equal to or lower than the second refrigerant temperature, there is a high possibility that the frost has not been completely melted, and the process proceeds to step S7.

Note that the determination in step S6 may not be performed immediately after the on-defrost operation ends in step S5. In a state shortly after the on-defrost operation is finished, even if residual frost is formed in the outdoor heat exchanger 103, the hot gas passes through the refrigerant pipe on the inlet side of the outdoor heat exchanger 103, so that this refrigerant This is because the pipe is heated and it may be determined that the detection result of the second refrigerant temperature sensor 151b is larger than the second refrigerant temperature Tb.

(Step S7 and Step S8: Reverse defrost operation)
The control device 119 performs reverse defrost operation. When the on-defrost operation ends, the control device 119 returns to step S0.

[Effects of refrigeration cycle apparatus 500 according to the present embodiment]
The refrigeration cycle apparatus 500 according to the present embodiment performs the residual frost determination based on the temperature of the outdoor heat exchanger 103 (second heat exchanger 103b) after performing the on-defrost operation. For example, when the frozen portion FI is formed in the second heat exchanger 103b (see FIG. 6A (d)), or there is residual frost throughout the outdoor heat exchanger 103 (see FIG. 6B (d)). The control device 119 determines that the detection result of the second refrigerant temperature sensor 151b is equal to or lower than the second refrigerant temperature Tb, and performs the reverse defrost operation. Thus, even if frost or the like is formed in the outdoor heat exchanger 103 after the on-defrost operation is finished, the remaining frost can be removed, so that the refrigerant and air flowing through the outdoor heat exchanger 103 can be removed. It can suppress that heat exchange efficiency falls. That is, the refrigeration cycle apparatus 500 according to the present embodiment suppresses a reduction in the heat exchange efficiency between the refrigerant flowing through the outdoor heat exchanger 103 and the air, and suppresses a reduction in the efficiency of the heating operation. be able to.

Refrigeration cycle apparatus 500 according to the present embodiment performs frosting determination based on the temperature of outdoor heat exchanger 103 (first heat exchanger 103a), and at least one of on-defrost operation and reverse defrost operation. Can be determined.
Then, refrigeration cycle apparatus 500 according to the present embodiment determines the amount of frost formation based on the outside air temperature, and determines whether to perform on-defrost operation or reverse defrost operation. Thereby, it can suppress that defrost operation time increases.

In the refrigeration cycle apparatus 500 according to the present embodiment, the aspect having the outside air temperature sensor 153 and the refrigerant temperature detection unit 151 has been described, but is not limited thereto. For example, outside air temperature information, refrigerant temperature information before flowing into the outdoor heat exchanger 103, and the like are acquired from a centralized controller that performs overall control of the plurality of refrigeration cycle apparatuses 500, and on-defrost operation and reverse defrost operation are performed. It may be determined whether or not.

In addition, the refrigeration cycle apparatus 500 according to the present embodiment supplies hot gas to the first heat exchanger 103a and then supplies hot gas to the second heat exchanger 103b during on-defrost operation. However, the present invention is not limited to this. For example, the hot gas may be supplied to the first heat exchanger 103a after the hot gas is supplied to the second heat exchanger 103b. In this case, when the hot gas is supplied to the first heat exchanger 103a, the lower second heat exchanger 103b functions as an evaporator, and the on-defrost operation ends. Become. For this reason, the possibility that a residual frost will be formed in the 2nd heat exchanger 103b becomes higher than the case of the control flow of Drawing 8 of this embodiment.

[Modification 1]
FIG. 9 is a first modification of the outdoor heat exchanger 103 of the refrigeration cycle apparatus 500 according to the present embodiment. FIG. 9A is a perspective view of the outdoor heat exchanger 103B, and FIG. 9B is a longitudinal sectional view of the outdoor heat exchanger 103B. The outdoor heat exchanger 103B is configured such that the first heat exchanger 103a is disposed above the second heat exchanger 103b, but the horizontal position thereof is shifted. Even if it is such an outdoor heat exchanger 103B, the effect similar to the refrigerating-cycle apparatus 500 which concerns on this Embodiment can be acquired.

[Modification 2]
FIG. 10 is a second modification of the outdoor heat exchanger 103 of the refrigeration cycle apparatus 500 according to the present embodiment. FIG. 10A is a perspective view of the outdoor heat exchanger 103C, and FIG. 10B is a longitudinal sectional view of the outdoor heat exchanger 103C. In the outdoor heat exchanger 103C, an installation part T on a plate used for installing the first heat exchanger 103a is arranged on the second heat exchanger 103b. Thus, even if a member is interposed between the first heat exchanger 103a and the second heat exchanger 103b, the same effect as the refrigeration cycle apparatus 500 according to the present embodiment can be obtained. it can.

[Modification 3]
FIG. 11 is a third modification of the outdoor heat exchanger 103 of the refrigeration cycle apparatus 500 according to the present embodiment. Fig.11 (a) is a perspective view of outdoor heat exchanger 103D, FIG.10 (b) is a longitudinal cross-sectional view of outdoor heat exchanger 103D. In the outdoor heat exchanger 103D, two first heat exchangers 103a are arranged as upper heat exchangers, and two second heat exchangers 103b are arranged as lower heat exchangers. That is, the outdoor heat exchanger 103D has four heat exchangers. Thus, the heat exchanger which comprises outdoor heat exchanger 103D is not limited to two, Three or more may be sufficient. Even in the third modification, the same effect as that of the refrigeration cycle apparatus 500 according to the present embodiment can be obtained.

[Modification 4]
FIG. 12 is a fourth modification of the outdoor heat exchanger 103 of the refrigeration cycle apparatus 500 according to the present embodiment. FIG. 12A is a perspective view of the outdoor heat exchanger 103E, and FIG. 12B is a longitudinal sectional view of the outdoor heat exchanger 103E. The first heat exchanger 103a of the outdoor heat exchanger 103E is inclined so that one end side is located on the lower side and the other end side is located on the upper side. The second heat exchanger 103b is inclined so that one end side is located on the upper side and the other end side is located on the lower side. Thus, even if the heat exchanger constituting the outdoor heat exchanger 103 is inclined, the same effect as that of the refrigeration cycle apparatus 500 according to the present embodiment can be obtained.

[Modification 5]
FIG. 13 is a fifth modification of the outdoor heat exchanger 103 of the refrigeration cycle apparatus 500 according to the present embodiment. FIG. 13A is a perspective view of the outdoor heat exchanger 103F, and FIG. 13B is a longitudinal sectional view of the outdoor heat exchanger 103F. The outdoor heat exchanger 103F is not formed by stacking two stages of heat exchangers, but is configured by stacking three stages of heat exchangers. Thus, the number of stages of the outdoor heat exchanger 103F is not limited to two, and may be three or more. For example, when only three stages of heat exchangers are stacked on the outdoor heat exchanger 103F, for example, on-defrost operation and reverse defrost operation may be performed as follows.

In the on-defrost operation, in the first operation mode, hot gas is supplied to the uppermost heat exchanger 103c, and the other functions as an evaporator. In the second operation mode, hot gas is supplied to the heat exchanger 103aa at the intermediate stage, and the other functions as an evaporator. In the third operation mode, hot gas is supplied to the lowermost heat exchanger 103bb and the other functions as an evaporator.
In reverse defrost operation, the refrigerant is supplied to all of the uppermost heat exchanger 103c, the intermediate heat exchanger 103aa, and the lowermost heat exchanger 103bb.

Even in the fifth modification, the same effect as that of the refrigeration cycle apparatus 500 according to the present embodiment can be obtained.

100 outdoor unit, 101 compressor, 102 four-way switching valve, 103 outdoor heat exchanger, 103B outdoor heat exchanger, 103C outdoor heat exchanger, 103D outdoor heat exchanger, 103E outdoor heat exchanger, 103F outdoor heat exchanger, 103a 1st heat exchanger, 103aa heat exchanger, 103b 2nd heat exchanger, 103bb heat exchanger, 103c heat exchanger, 104 accumulator, 105a switching valve, 105b switching valve, 106a switching valve, 106b switching valve, 109 Outdoor fan, 119 control device, 141 high pressure sensor, 142 low pressure sensor, 151 refrigerant temperature detector, 151a first refrigerant temperature sensor, 151b second refrigerant temperature sensor, 153 outdoor air temperature sensor, 300 indoor unit, 311 throttle device, 312 room Exchanger, 313 indoor fan, 500 refrigeration cycle device, C refrigerant circuit, F frost, FI freezing part, T installation part, Ta first refrigerant temperature, Tair outdoor temperature, Tb second refrigerant temperature, t heating operation elapsed time .

Claims

In a refrigeration cycle apparatus including a compressor, an indoor heat exchanger, an expansion device, and an outdoor heat exchanger, and having a refrigerant circuit in which these are connected by refrigerant piping,
A control device for controlling the execution of the defrost operation based on the temperature of the outdoor heat exchanger and the outside air temperature;
With
The outdoor heat exchanger is
Comprising at least a first heat exchanger and a second heat exchanger disposed below the first heat exchanger;
The controller is
When the outside air temperature meets the preset condition,
One of the first heat exchanger and the second heat exchanger is caused to function as an evaporator, and the other is supplied with hot gas discharged from the compressor without passing through the indoor heat exchanger. On-defrost operation,
When the temperature of the outdoor heat exchanger satisfies a preset condition after performing the on-defrost operation,
A refrigeration cycle apparatus configured to perform a reverse defrost operation in which the refrigerant that has passed through the indoor heat exchanger is supplied from the compressor to the first heat exchanger and the second heat exchanger.
A refrigerant temperature detector attached to the outdoor heat exchanger for detecting a refrigerant temperature;
An outside temperature sensor for detecting the outside temperature,
The controller is
When the detection result of the outside air temperature sensor satisfies a preset condition, the on-defrost operation is performed,
The refrigeration cycle according to claim 1, wherein after the on-defrost operation is performed, the reverse defrost operation is performed when a detection result of the refrigerant temperature detection unit satisfies a preset condition. apparatus.
The controller is
When performing the on-defrost operation,
The first heat exchanger and the second heat exchanger are configured to perform control to switch between one that functions as the evaporator and one that supplies the hot gas. The refrigeration cycle apparatus described in 1.
The controller is
When performing the on-defrost operation,
After supplying the hot gas to the first heat exchanger and causing the second heat exchanger to function as the evaporator,
The refrigeration cycle apparatus according to claim 3, wherein the refrigeration cycle apparatus is configured to control the first heat exchanger as the evaporator and to supply the hot gas to the second heat exchanger.
The refrigerant temperature sensor
A first refrigerant temperature sensor attached to the first heat exchanger and detecting a refrigerant temperature of the first heat exchanger;
A second refrigerant temperature sensor attached to the second heat exchanger and detecting a refrigerant temperature of the second heat exchanger;
The controller is
When the detection result of the first refrigerant temperature sensor is equal to or lower than a first refrigerant temperature set in advance and the detection result of the outside air temperature sensor is higher than a preset temperature, the on-defrost operation is performed. ,
The refrigeration cycle apparatus according to claim 4, wherein the reverse defrosting operation is performed when a detection result of the second refrigerant temperature sensor is equal to or lower than a second refrigerant temperature set in advance.
The first refrigerant temperature sensor is
Arranged at a position to detect the refrigerant temperature before flowing into the first heat exchanger;
The second refrigerant temperature sensor is
The refrigeration cycle apparatus according to claim 5, wherein the refrigeration cycle apparatus is disposed at a position for detecting a refrigerant temperature before flowing into the second heat exchanger.
An outdoor fan attached to the outdoor heat exchanger and supplying air to the outdoor heat exchanger;
An indoor fan attached to the indoor heat exchanger and supplying air to the indoor heat exchanger;
The controller is
The refrigeration cycle apparatus according to any one of claims 1 to 6, wherein the outdoor fan and the indoor fan are stopped during the reverse defrost operation.
The refrigeration cycle apparatus according to any one of claims 1 to 7, further comprising: an outdoor unit on which at least a compressor and an outdoor heat exchanger are mounted; and an indoor unit on which at least the indoor heat exchanger is mounted. Air conditioner.