Refrigeration Cycle Equipment

Abstract

This refrigeration cycle device comprises: a compressor; a flow path switching device; an indoor heat exchanger; a throttle device; a plurality of flow control valves; and a refrigerant circuit to which a plurality of outdoor heat exchangers are connected by piping and in which a refrigerant circulates. The refrigerant circuit is configured such that the refrigerant flows in parallel through each of the plurality of outdoor heat exchangers during a heating operation, and is configured such that the refrigerant flows in series through some of the plurality of outdoor heat exchangers serving as the upstream side and the remaining plurality of outdoor heat exchangers that serve as the downstream side during a cooling operation and during a defrosting operation. A temperature sensor is provided to piping on an outlet side of an outdoor heat exchange serving as the downstream side during the cooling operation and during the defrosting operation.

Description

[Technical field]

[0001] The present disclosure relates to a refrigeration cycle device that performs a defrost operation. [Background technology]

[0002] Conventionally, there is a refrigeration cycle device that performs a defrost operation (see, for example, Patent Document 1). In Patent Document 1, the circuit flowing from the expansion valve to the outdoor heat exchanger is divided into an upper part and a lower part. In other words, in Patent Document 1, the upper and lower parts of the outdoor heat exchanger divided vertically are connected in parallel, and a temperature sensor is provided on each of the outlet pipes when the outdoor heat exchanger functions as a condenser. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2012-63033 A Summary of the Invention [Problem to be solved by the invention]

[0004] In Patent Document 1, since it is not known which of the upper and lower parts of the outdoor heat exchanger will complete defrosting first during defrosting operation, a temperature sensor is provided on each of the outlet pipes when the outdoor heat exchanger functions as a condenser, and the completion of defrosting is detected for each of the upper and lower parts of the outdoor heat exchanger based on the detection values ​​of each temperature sensor. Therefore, in order to detect the completion of defrosting, temperature sensors are required for the number of divisions of the outdoor heat exchanger, and the number of temperature sensors required increases as the number of divisions of the outdoor heat exchanger increases. As a result, there are problems such as increased costs and a complex algorithm for determining the completion of defrosting.

[0005] The present disclosure has been made to solve the above problems, and aims to provide a refrigeration cycle device that is less costly and has a less complex algorithm than conventional devices. [Means for solving the problem]

[0006] The refrigeration cycle device according to the present disclosure includes a compressor, a flow path switching device, an indoor heat exchanger, a throttling device, a plurality of flow control valves, and a plurality of outdoor heat exchangers, which are connected by piping, and includes a refrigerant circuit through which a refrigerant circulates. The plurality of outdoor heat exchangers are arranged in one outdoor unit, the outdoor unit is a top-flow type having an outdoor fan provided at the top, the plurality of outdoor heat exchangers are three in number, and are arranged on the left side, right side, and rear side of the outdoor unit, respectively; the refrigerant circuit is configured such that, during heating operation, the refrigerant flows in parallel through each of the plurality of outdoor heat exchangers, and, during cooling operation and defrost operation, the refrigerant flows in series through some of the plurality of outdoor heat exchangers that are upstream and the remaining some that are downstream, The outdoor heat exchanger on the upstream side is the outdoor heat exchanger arranged on the left side and right side of the outdoor unit, and the outdoor heat exchanger on the downstream side is the outdoor heat exchanger arranged on the rear surface of the outdoor unit, Downstream during cooling and defrost operation The outdoor unit is disposed on the rear surface of the outdoor unit. The piping on the outlet side of the outdoor heat exchanger only A temperature sensor is provided. Effect of the Invention

[0007] According to the refrigeration cycle device of the present disclosure, the refrigerant circuit is configured such that the refrigerant flows in parallel through each of the multiple outdoor heat exchangers during heating operation, and the refrigerant flows in series through some of the multiple outdoor heat exchangers that are upstream and the remaining part that are downstream during cooling operation and defrost operation. Therefore, by checking the completion of defrosting of the downstream outdoor heat exchanger, it is possible to know that defrosting is completed in all outdoor heat exchangers. As a result, it is necessary to provide the same number of temperature sensors as the downstream outdoor heat exchangers, which makes it possible to reduce costs compared to the conventional technology, and also, since the number of outdoor heat exchangers for which the completion of defrosting is checked can be reduced, the complexity of the algorithm can be suppressed compared to the conventional technology. [Brief description of the drawings]

[0008] [Figure 1] 1 is a refrigerant circuit diagram of a refrigeration cycle device according to a first embodiment. [Diagram 2]1 is a perspective view that typically shows an outdoor heat exchanger of a refrigeration cycle apparatus according to a first embodiment. [Diagram 3] FIG. 2 is a refrigerant circuit diagram during cooling operation of the refrigeration cycle device according to the first embodiment. [Figure 4] FIG. 2 is a refrigerant circuit diagram during heating operation of the refrigeration cycle device according to the first embodiment. [Diagram 5] FIG. 4 is a refrigerant circuit diagram of a first modified example of the refrigeration cycle device according to the first embodiment. [Figure 6] FIG. 4 is a refrigerant circuit diagram of a second modified example of the refrigeration cycle device according to the first embodiment. [Figure 7] FIG. 11 is a front perspective view of an outdoor unit of a refrigeration cycle device according to a second embodiment. [Figure 8] FIG. 11 is a rear perspective view of an outdoor unit of a refrigeration cycle device according to a second embodiment. [Figure 9] FIG. 11 is an exploded front perspective view of an outdoor unit of a refrigeration cycle device according to a second embodiment. [Figure 10] FIG. 11 is an exploded perspective side view of an outdoor unit of a refrigeration cycle device according to a second embodiment. [Figure 11] 13 is a diagram showing temperature characteristics of a refrigerant when the refrigerant flows in series through an outdoor heat exchanger located on the upstream side and an outdoor heat exchanger located on the downstream side of a refrigeration cycle device according to embodiment 3. FIG. [Figure 12] FIG. 11 is a diagram showing temperature characteristics of a refrigerant when the refrigerant is caused to flow in parallel through each outdoor heat exchanger of a refrigeration cycle device according to embodiment 3. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. Note that the present disclosure is not limited to the embodiments described below. In addition, the size relationships of the components in the drawings may differ from the actual ones.

[0010] Embodiment 1 <Configuration of refrigeration cycle device> Fig. 1 is a refrigerant circuit diagram of a refrigeration cycle device according to the first embodiment. As shown in Fig. 1, the refrigeration cycle device according to the first embodiment includes an outdoor unit 10 and an indoor unit 20. The outdoor unit 10 includes a compressor 11, a flow path switching device 12, three outdoor heat exchangers 30 (outdoor heat exchangers 30a to 30c), two flow rate control valves 13 (flow rate control valve 13a and flow rate control valve 13b), an on-off valve 14, a check valve 15, an accumulator 16, a temperature sensor 17, and an outdoor fan (not shown). The indoor unit 20 includes a throttling device 21, an indoor heat exchanger 22, and an indoor fan (not shown).

[0011] The refrigeration cycle device is also composed of an outdoor unit 10 and an indoor unit 20, and is provided with a refrigerant circuit 100 through which a refrigerant circulates. Specifically, the refrigerant circuit 100 is composed of a compressor 11, a flow path switching device 12, an indoor heat exchanger 22, a throttling device 21, a flow control valve 13, and an outdoor heat exchanger 30, which are successively connected by piping 101. This refrigeration cycle device is capable of both cooling operation and heating operation by switching the flow path switching device 12, and is also capable of defrost operation.

[0012] The compressor 11 draws in a low-temperature, low-pressure refrigerant, compresses the drawn refrigerant, and discharges a high-temperature, high-pressure refrigerant. The compressor 11 is, for example, an inverter compressor whose capacity, which is the amount of discharge per unit time, is controlled by changing the operating frequency.

[0013] The flow path switching device 12 is, for example, a four-way valve, and switches between cooling operation and heating operation by switching the direction of refrigerant flow. During cooling operation, the flow path switching device 12 switches to the state shown in Fig. 3, which will be described later, and connects the discharge side of the compressor 11 to the outdoor heat exchanger 30. During heating operation, the flow path switching device 12 switches to the state shown in Fig. 4, and connects the discharge side of the compressor 11 to the indoor heat exchanger 22.

[0014] The outdoor heat exchanger 30 exchanges heat between the outdoor air and the refrigerant. During cooling operation, the outdoor heat exchanger 30 functions as a condenser that releases heat from the refrigerant to the outdoor air to condense the refrigerant. During heating operation, the outdoor heat exchanger 30 absorbs heat from the outdoor air to evaporate the refrigerant, and functions as an evaporator that cools the outdoor air with the heat of vaporization.

[0015] The outdoor fan supplies outdoor air to the outdoor heat exchanger 30, and the amount of air sent to the outdoor heat exchanger 30 is adjusted by controlling the rotation speed.

[0016] The flow rate control valve 13 is, for example, an electronic expansion valve that can adjust the throttle opening, and controls the pressure of the refrigerant flowing into the exterior heat exchanger 30 that functions as an evaporator by adjusting the opening.

[0017] The on-off valve 14 is a two-way valve that allows the refrigerant to flow when open and restricts the flow of the refrigerant when closed, and is open during cooling operation and closed during heating operation. The check valve 15 prevents the refrigerant from flowing backwards and restricts the refrigerant to flow in only one direction. A two-way valve may be provided instead of the check valve 15.

[0018] The accumulator 16 is provided on the suction side of the compressor 11, and serves to store surplus refrigerant generated due to the difference in operating state between cooling operation and heating operation, or surplus refrigerant due to a transient change in operation, etc. Furthermore, the accumulator 16 serves to prevent liquid compression of the compressor 11.

[0019] The temperature sensor 17 is, for example, a thermistor, and is provided in the pipe 101a between the outdoor heat exchanger 30c and the flow rate control valve 13b to detect the temperature of the refrigerant flowing through the pipe 101a. As will be described later, this temperature sensor 17 is provided only in the pipe 101a on the outlet side of the outdoor heat exchanger 30c, which is downstream during cooling operation and defrost operation.

[0020] The throttling device 21 is, for example, an electronic expansion valve capable of adjusting the opening degree of the throttling, and by adjusting the opening degree, the pressure of the refrigerant flowing into the outdoor heat exchanger 30 or the indoor heat exchanger 22 is controlled. Note that, although the throttling device 21 is provided in the indoor unit 20 in the first embodiment, it may be provided in the outdoor unit 10, and the installation location is not limited.

[0021] The indoor heat exchanger 22 exchanges heat between the indoor air and the refrigerant. During cooling operation, the indoor heat exchanger 22 functions as an evaporator that evaporates the refrigerant and cools the indoor air with the heat of vaporization. During heating operation, the indoor heat exchanger 22 functions as a condenser that radiates heat of the refrigerant to the indoor air and condenses the refrigerant.

[0022] The indoor fan supplies indoor air to the indoor heat exchanger 22, and the amount of air sent to the indoor heat exchanger 22 is adjusted by controlling the rotation speed.

[0023] Fig. 2 is a perspective view showing a schematic diagram of the outdoor heat exchanger 30 of the refrigeration cycle apparatus according to the first embodiment. The white arrows in Fig. 2 indicate the flow direction of air, and the black arrows in Fig. 2 indicate the flow of refrigerant. The inlet and outlet shown in Fig. 2 indicate the inlet and outlet when the outdoor heat exchanger 30 functions as a condenser. The outdoor heat exchangers 30a to 30c are of a corrugated fin tube type having a parallel piping configuration. The outdoor heat exchangers 30a to 30c are connected in parallel to each other in the refrigerant circuit 100.

[0024] Each outdoor heat exchanger 30 has two distribution headers 31 (distribution header 31A and distribution header 31B), a turn-back header 33, a plurality of flat tubes 34, and a plurality of corrugated fins 35. In the following, the distribution header 31 and the turn-back header 33 are also simply referred to as headers.

[0025] In the outdoor heat exchanger 30 according to the first embodiment, a pair of headers consisting of two distribution headers 31 and a turn-up header 33 are arranged above and below in the height direction. In the outdoor unit 10, devices such as the compressor 11 are installed below the outdoor unit 10, so the turn-up header 33 is arranged above and the two distribution headers 31 are arranged below the turn-up header 33 due to piping connections and the like.

[0026] Between the two distribution headers 31 and the turn-back header 33, groups of flat tubes 34 (hereinafter also referred to as flat tube groups) composed of a plurality of flat tubes 34 whose flat surfaces face each other so as to be perpendicular to the distribution header 31 and the turn-back header 33 and parallel to each other are arranged in two rows in the air flow direction. The group of flat tubes 34 in one row is connected to one distribution header 31. Here, H shown in FIG. 2 indicates the height of the group of flat tubes 34 in one row, and L shown in FIG. 2 indicates the width of the group of flat tubes 34 in one row.

[0027] The distribution headers 31 are pipes connected to other devices constituting the refrigeration cycle apparatus, through which the refrigerant, a fluid that serves as a heat exchange medium, flows in and out, and through which the refrigerant branches or merges. Each distribution header 31 has refrigerant inlet / outlet pipes 32 (refrigerant inlet / outlet pipes 32A and refrigerant inlet / outlet pipes 32B) through which the refrigerant from the outside flows in and out. The turn-back header 33 is a header that serves as a bridge that turns back from a group of flat tubes 34 in one row to a group of flat tubes 34 in the other row.

[0028] The flat tube 34 is a heat transfer tube having a flat cross section, a flat outer surface on the long side of the flat shape along the air flow direction, and a curved outer surface on the short side perpendicular to the long direction. The flat tube 34 according to the first embodiment is a multi-hole flat tube having a plurality of holes that serve as a refrigerant flow path inside the tube. In the first embodiment, the holes of the flat tube 34 are formed facing the height direction to serve as a flow path between the distribution header 31 and the turn-back header 33. As described above, the flat tubes 34 are arranged at equal intervals in the horizontal direction with the outer surfaces on the long sides facing each other. When manufacturing the outdoor heat exchanger 30 according to the first embodiment, the flat tubes 34 are inserted into insertion holes (not shown) of the distribution header 31 and the turn-back header 33, brazed, and joined. For example, a brazing material containing aluminum is used for the brazing material. This allows the distribution header 31, the turn-back header 33, and the inside of each flat tube 34 to communicate with each other.

[0029] The corrugated fins 35 have a wave shape and are disposed between two adjacent flat tubes 34, with a plurality of apexes joined to the flat surfaces of the flat tubes 34. Note that, in the first embodiment, the outdoor heat exchanger 30 is a corrugated fin tube type in which groups of flat tubes 34 are arranged in two rows, but is not limited thereto, and may be a corrugated fin tube type in which groups of flat tubes 34 are arranged in only one row or three or more rows.

[0030] Fig. 3 is a refrigerant circuit diagram of the refrigeration cycle device according to embodiment 1 during cooling operation. Fig. 4 is a refrigerant circuit diagram of the refrigeration cycle device according to embodiment 1 during heating operation. Note that arrows shown in Figs. 3 and 4 indicate the flow of refrigerant. Next, with reference to Figs. 3 and 4, the operation of the refrigeration cycle device during each operation will be described.

[0031] <Cooling operation> In the cooling operation, as shown in Fig. 3, the flow path switching device 12 is switched so that the discharge side of the compressor 11 is connected to the outdoor heat exchanger 30, the on-off valve 14 is open, the flow rate control valve 13a is fully closed, and the flow rate control valve 13b is open. The high-temperature, high-pressure gas refrigerant discharged from the compressor 11 flows into the outdoor heat exchangers 30a and 30b via the flow path switching device 12. The high-temperature, high-pressure gas refrigerant that flows into the outdoor heat exchangers 30a and 30b exchanges heat with the outdoor air taken in by the outdoor fan, condenses while releasing heat, and becomes a medium-temperature, high-pressure two-phase gas-liquid refrigerant that flows out of the outdoor heat exchangers 30a and 30b. The medium-temperature, high-pressure two-phase gas-liquid refrigerant that flows out of the outdoor heat exchangers 30a and 30b flows into the outdoor heat exchanger 30c via the on-off valve 14. The medium-temperature, high-pressure, two-phase gas-liquid refrigerant that flows into the outdoor heat exchanger 30c exchanges heat with the outdoor air taken in by the outdoor fan, condenses while releasing heat, and becomes a low-temperature, high-pressure liquid refrigerant, which flows out of the outdoor heat exchanger 30c. In other words, during cooling operation, the refrigerant circuit 100 is configured so that the refrigerant flows in series through the outdoor heat exchangers 30a and 30b on the upstream side and the outdoor heat exchanger 30c on the downstream side among the multiple outdoor heat exchangers 30a to 30c. The low-temperature, high-pressure liquid refrigerant that flows out of the outdoor heat exchanger 30c flows through the throttling device 21 via the flow control valve 13b, is depressurized by the throttling device 21, becomes a low-temperature, low-pressure, two-phase gas-liquid refrigerant, and flows into the indoor heat exchanger 22. The low-temperature, low-pressure two-phase gas-liquid refrigerant that flows into the indoor heat exchanger 22 exchanges heat with the indoor air taken in by the indoor fan, absorbing heat and evaporating, cooling the indoor air and becoming a low-temperature, low-pressure gas refrigerant before flowing out of the indoor heat exchanger 22. The low-temperature, low-pressure gas refrigerant that flows out of the indoor heat exchanger 22 is sucked into the compressor 11 via the flow switching device 12 and the accumulator 16, and becomes a high-temperature, high-pressure gas refrigerant again.

[0032] <Heating operation> In the heating operation, as shown in FIG. 4, the flow switching device 12 is switched so that the discharge side of the compressor 11 is connected to the indoor heat exchanger 22, the on-off valve 14 is closed, and the flow rate control valves 13a and 13b are open. The high-temperature, high-pressure gas refrigerant discharged from the compressor 11 flows into the indoor heat exchanger 22 via the flow switching device 12. The high-temperature, high-pressure gas refrigerant that flows into the indoor heat exchanger 22 exchanges heat with the indoor air taken in by the indoor fan and condenses while releasing heat, heating the indoor air and becoming a low-temperature, high-pressure liquid refrigerant, which flows out of the indoor heat exchanger 22. The low-temperature, high-pressure liquid refrigerant that flows out of the indoor heat exchanger 22 flows into the throttling device 21, where it is decompressed to become a low-temperature, low-pressure gas-liquid two-phase refrigerant, which flows into the outdoor heat exchangers 30a to 30c via the flow rate control valves 13a and 13b. The low-temperature, low-pressure two-phase gas-liquid refrigerant that flows into the outdoor heat exchangers 30a-30c exchanges heat with the outdoor air taken in by the outdoor fan, absorbing heat and evaporating, becoming a low-temperature, low-pressure gas refrigerant that flows out of the outdoor heat exchangers 30a-30c. In other words, during heating operation, the refrigerant circuit 100 is configured so that the refrigerant flows in parallel through each of the multiple outdoor heat exchangers 30a-30c. The low-temperature, low-pressure gas refrigerant that flows out of the outdoor heat exchangers 30a-30c is sucked into the compressor 11 via the flow switching device 12 and the accumulator 16, and becomes a high-temperature, high-pressure gas refrigerant again.

[0033] <Defrost operation> When heating operation is performed in a low-temperature environment where the surface temperatures of the flat tubes 34 and the corrugated fins 35 shown in Fig. 2 are below 0°C, frost forms on the outdoor heat exchanger 30. When the amount of frost on the outdoor heat exchanger 30 exceeds a certain level, the air passage of the outdoor heat exchanger 30 through which the air generated by the outdoor fan passes is blocked, and the performance of the outdoor heat exchanger 30 decreases, resulting in a decrease in heating performance. Therefore, in low outdoor air conditions where frost forms on the outdoor heat exchanger 30, a defrost operation is performed to melt the frost on the surface of the outdoor heat exchanger 30 in order to suppress a decrease in heating performance.

[0034] As shown in Fig. 3, in the defrost operation, the indoor fan is stopped, the flow path switching device 12 is switched to the same state as in the cooling operation, and the on-off valve 14 and the flow rate control valves 13a and 13b are also in the same state as in the cooling operation. In the defrost operation, the high-temperature, high-pressure gas refrigerant discharged from the compressor 11 flows into the outdoor heat exchangers 30a and 30b, and then flows into the outdoor heat exchanger 30c. In other words, in the defrost operation, as in the refrigerant operation, the refrigerant circuit 100 is configured such that the refrigerant flows in series between the outdoor heat exchangers 30a and 30b on the upstream side and the outdoor heat exchanger 30c on the downstream side among the multiple outdoor heat exchangers 30a to 30c.

[0035] In this way, during defrost operation, the outdoor heat exchangers 30a to 30c are divided into upstream and downstream sides, and the upstream outdoor heat exchangers 30a, 30b and the downstream outdoor heat exchanger 30c are connected in series to form a circuit configuration. In this way, the refrigerant with a high temperature flows first through the upstream outdoor heat exchangers 30a, 30b, and then the refrigerant whose temperature has been reduced by heat exchange with the outdoor air in the upstream outdoor heat exchangers 30a, 30b flows through the downstream outdoor heat exchanger 30c. Therefore, even if factors that hinder defrosting, such as outside wind, are different for each of the outdoor heat exchangers 30a to 30c, the order in which defrosting is completed is that the upstream outdoor heat exchangers 30a, 30b first, and then the downstream outdoor heat exchanger 30c. In other words, by confirming the completion of defrosting in the downstream outdoor heat exchanger 30c, it is possible to know that defrosting is completed in all outdoor heat exchangers 30. As a result, it is only necessary to provide the same number of temperature sensors 17 as the number of downstream outdoor heat exchangers 30c, making it possible to reduce costs compared to the conventional method, and since the number of outdoor heat exchangers 30 for checking the completion of defrost can be reduced, the complexity of the algorithm can be suppressed compared to the conventional method. Here, whether defrost is completed in all outdoor heat exchangers 30 is determined based on the detection value of the temperature sensor 17 and a preset threshold value, and if the detection value of the temperature sensor 17 is equal to or greater than the threshold value, it is determined that defrost is completed.

[0036] In the first embodiment, the flow rate control valve 13 is configured to be capable of adjusting the opening degree, but is not limited thereto and may be configured as a two-way valve that simply opens and closes, etc. However, if the flow rate control valves 13a, 13b are configured to be capable of adjusting the opening degree, the amount of frost formed on the outdoor heat exchangers 30a, 30b and the outdoor heat exchanger 30c functioning as evaporators can be adjusted by adjusting the opening degree of the flow rate control valves 13a, 13b, respectively, during heating operation.

[0037] FIG. 5 is a refrigerant circuit diagram of a first modified example of the refrigeration cycle device according to the first embodiment. The number of the outdoor heat exchangers 30 is not limited to three, and may be two or four or more. For example, when the number of the outdoor heat exchangers 30 is four, the refrigerant circuit 100 is configured as shown in FIG. 5. That is, in the refrigerant circuit 100, the outdoor heat exchanger 30d and the flow rate control valve 13c are connected in parallel to the outdoor heat exchanger 30c and the flow rate control valve 13b. The temperature sensor 17 is provided in each of the pipe 101a1 between the outdoor heat exchanger 30c and the flow rate control valve 13b, and the pipe 101a2 between the outdoor heat exchanger 30d and the flow rate control valve 13c. That is, the temperature sensor 17 is provided in each of the pipes 101a1 and 101a2 on the outlet side of the outdoor heat exchangers 30c and 30d, which are downstream during cooling operation and defrost operation. Here, whether defrosting has been completed in all outdoor heat exchangers 30 is determined based on the detection value of the temperature sensor 17 and a preset threshold value, and if the detection values ​​of both temperature sensors 17 are equal to or higher than the threshold value, it is determined that defrosting has been completed.

[0038] FIG. 6 is a refrigerant circuit diagram of a second modified example of the refrigeration cycle device according to the first embodiment. For example, when the number of the outdoor heat exchangers 30 is four, the refrigerant circuit 100 may be configured as shown in FIG. 6. That is, during cooling operation, the refrigerant circuit 100 is configured so that the refrigerant flows in series through the outdoor heat exchangers 30a-30c on the upstream side and the outdoor heat exchanger 30d on the downstream side among the multiple outdoor heat exchangers 30a-30d. Also, during heating operation and defrost operation, the refrigerant circuit 100 is configured so that the refrigerant flows in parallel through each of the multiple outdoor heat exchangers 30a-30d. A temperature sensor 17 is provided in the pipe 101a between the outdoor heat exchanger 30d and the flow rate control valve 13b. That is, only one temperature sensor 17 is provided in the pipe 101a on the outlet side of the outdoor heat exchanger 30d on the downstream side during cooling operation and defrost operation. Here, whether defrosting is complete in all outdoor heat exchangers 30 is determined based on the detection value of temperature sensor 17 and a preset threshold value, and if the detection value of one temperature sensor 17 is equal to or greater than the threshold value, it is determined that defrosting is complete. With this circuit configuration, even if the number of outdoor heat exchangers 30 is five or more, only one temperature sensor 17 is required.

[0039] As described above, the refrigeration cycle device according to the first embodiment includes a compressor 11, a flow path switching device 12, an indoor heat exchanger 22, a throttling device 21, a plurality of flow control valves 13, and a plurality of outdoor heat exchangers 30 connected by piping 101, and includes a refrigerant circuit 100 in which a refrigerant circulates. The refrigerant circuit 100 is configured such that a refrigerant flows in parallel through each of the plurality of outdoor heat exchangers 30 during heating operation. The refrigerant circuit 100 is configured such that a refrigerant flows in series through some of the plurality of outdoor heat exchangers 30 that are upstream and the remaining parts that are downstream during cooling operation and defrost operation. The temperature sensor 17 is provided in the piping 101a on the outlet side of the outdoor heat exchanger 30 that is downstream during cooling operation and defrost operation.

[0040] According to the refrigeration cycle device of the first embodiment, the refrigerant circuit 100 is configured such that the refrigerant flows in parallel through each of the multiple outdoor heat exchangers 30 during heating operation. Also, the refrigerant circuit 100 is configured such that the refrigerant flows in series through some of the multiple outdoor heat exchangers 30 that are upstream and the remaining part that are downstream during cooling operation and defrost operation. Therefore, by confirming the completion of defrosting in the downstream outdoor heat exchanger 30, it is possible to know that defrosting is completed in all the outdoor heat exchangers 30. As a result, it is only necessary to provide the same number of temperature sensors 17 as the downstream outdoor heat exchangers 30, which allows for cost reduction compared to the conventional technology, and also allows for a reduction in the number of outdoor heat exchangers 30 for which the completion of defrosting is confirmed, which allows for a reduction in the number of algorithms compared to the conventional technology.

[0041] Moreover, in the refrigeration cycle apparatus according to the first embodiment, among the plurality of outdoor heat exchangers 30, the outdoor heat exchanger 30 that is on the downstream side during cooling operation and defrost operation is one.

[0042] According to the refrigeration cycle device of the first embodiment, it is possible to know that defrosting is completed in all the outdoor heat exchangers 30 simply by checking the completion of defrosting in one outdoor heat exchanger 30, so that it is possible to suppress the complexity of the algorithm compared to the conventional art. Also, since only one temperature sensor 17 is required, it is possible to reduce costs compared to the conventional art.

[0043] Moreover, in the refrigeration cycle apparatus according to the first embodiment, the temperature sensor 17 is provided between one outdoor heat exchanger 30 and one flow rate control valve 13, which is downstream during cooling operation and defrost operation.

[0044] According to the refrigeration cycle apparatus of the first embodiment, it is possible to reliably determine, with one temperature sensor 17, that defrosting has been completed in all of the outdoor heat exchangers 30.

[0045] Embodiment 2 Hereinafter, the second embodiment will be described, but explanations of parts that overlap with the first embodiment will be omitted, and parts that are the same as or equivalent to the first embodiment will be given the same reference numerals.

[0046] Fig. 7 is a perspective view of the outdoor unit 10 of the refrigeration cycle apparatus according to embodiment 2, as viewed from the front. Fig. 8 is a perspective view of the outdoor unit 10 of the refrigeration cycle apparatus according to embodiment 2, as viewed from the back. Fig. 9 is an exploded perspective view of the outdoor unit 10 of the refrigeration cycle apparatus according to embodiment 2, as viewed from the front. Fig. 10 is an exploded perspective view of the outdoor unit 10 of the refrigeration cycle apparatus according to embodiment 2, as viewed from the side.

[0047] As shown in Figs. 7 to 10, the outdoor unit 10 according to the second embodiment is a top-flow type having an air outlet 41 for an outdoor fan 42 at the upper center of a housing 40 forming an outer shell. As shown in Fig. 9, a compressor 11 and the like are housed inside the housing 40. As shown in Figs. 7 and 8, an air outlet 41 is formed at the upper center of the housing 40, and as shown in Figs. 9 and 10, an outdoor fan 42 is disposed directly below the air outlet 41. As shown in Fig. 7, a removable service panel 43 is provided on the front side of the housing 40. As shown in Figs. 9 and 10, the outdoor heat exchanger 30 is flat and is provided independently on three of the four side surfaces of the housing 40, specifically, on the left side, right side, and rear side. Also, one of the outdoor heat exchangers 30a and 30b that is upstream during cooling operation and defrost operation is provided on the left side of the housing 40. The other of the outdoor heat exchangers 30a and 30b, which is the upstream side during cooling operation and defrost operation, is provided on the right side of the housing 40. The outdoor heat exchanger 30c, which is the downstream side during cooling operation and defrost operation, is provided on the rear side of the housing 40. Here, the outdoor heat exchangers 30a to 30c are arranged so that when functioning as a condenser, the refrigerant inlet is inside the housing 40 and the refrigerant outlet is outside the housing 40 and on the windward side of the outdoor air flow. In Figs. 9 and 10, the outdoor heat exchanger 30a is provided on the right side of the housing 40 and the outdoor heat exchanger 30b is provided on the left side of the housing 40, but they may be provided inversely.

[0048] The area of ​​the flat tube group of the outdoor heat exchanger 30a provided on the left and right side surfaces of the housing 40 (hereinafter also referred to as the flat tube group area S1) is the same as the area of ​​the flat tube group of the outdoor heat exchanger 30b (hereinafter also referred to as the flat tube group area S2) (S1=S2), and the sum (S1+S2) of the flat tube group area S1 and the flat tube group area S2 is larger than the area of ​​the flat tube group of the outdoor heat exchanger 30c provided on the rear surface of the housing 40 (hereinafter also referred to as the flat tube group area S3) ((S1+S2)>S3). Here, the flat tube group areas S1 to S3 are the product (H×L) of the height H and width L of the group of flat tubes 34 in the row on the windward side of the outdoor air flow of the outdoor heat exchanger 30. The flat tube group area S1 and the flat tube group area S2 do not have to be strictly the same, but may be approximately the same.

[0049] In this way, by making the sum of the flat tube group area S1 and the flat tube group area S2 larger than the flat tube group area S3, the amount of frost formed during heating operation under low outdoor air conditions is greater in the upstream outdoor heat exchangers 30a and 30b than in the downstream outdoor heat exchanger 30c. Therefore, during defrost operation, a refrigerant with a high temperature is first introduced into the upstream outdoor heat exchangers 30a and 30b where the amount of frost is large, and a refrigerant that has been partially released by the upstream outdoor heat exchangers 30a and 30b and then merges with the upstream outdoor heat exchangers 30a and 30b, that is, a refrigerant with a lower temperature is introduced into the downstream outdoor heat exchanger 30c where the amount of frost is small. In this way, it is possible to input the amount of heat of melting according to the amount of frost formed, and defrosting can be performed efficiently.

[0050] Furthermore, by making the flat tube group area S1 and the flat tube group area S2 the same, the high temperature refrigerant can be evenly distributed and flowed into the outdoor heat exchanger 30a and the outdoor heat exchanger 30b. This makes it possible to suppress remaining frost due to drift of the flow to the left and right side surfaces of the housing 40.

[0051] As described above, in the refrigeration cycle apparatus according to the second embodiment, the multiple outdoor heat exchangers 30 are arranged in one outdoor unit 10. The outdoor unit 10 is a top flow type in which the outdoor fan 42 is provided at the top, and the multiple outdoor heat exchangers 30 are three in number, and are arranged on the left side, right side, and rear side of the outdoor unit 10, respectively. In addition, the area of ​​the flattened tube group of the outdoor heat exchanger 30 arranged on the left side of the outdoor unit 10 (flat tube group area S1) is the same as the area of ​​the flattened tube group of the outdoor heat exchanger 30 arranged on the right side of the outdoor unit 10 (flat tube group area S2), and the sum of the area of ​​the flattened tube group of the outdoor heat exchanger 30 arranged on the left side of the outdoor unit 10 (flat tube group area S1) and the area of ​​the flattened tube group of the outdoor heat exchanger 30 arranged on the right side of the outdoor unit 10 (flat tube group area S2) is greater than the area of ​​the flattened tube group of the outdoor heat exchanger 30 arranged on the rear side of the outdoor unit 10 (flat tube group area S3).

[0052] According to the refrigeration cycle device of the second embodiment, the sum of the flat tube group area S1 and the flat tube group area S2 is made larger than the flat tube group area S3. By doing so, the amount of frost formed during heating operation under low outdoor air conditions is greater in the outdoor heat exchanger 30 on the upstream side than in the outdoor heat exchanger 30 on the downstream side. Therefore, during defrost operation, a refrigerant with a high temperature is first flowed into the outdoor heat exchanger 30 on the upstream side where the amount of frost is large, and a refrigerant that has been partially dissipated by the outdoor heat exchanger 30 on the upstream side and then merged therewith, that is, a refrigerant with a lowered temperature is flowed into the outdoor heat exchanger 30 on the downstream side where the amount of frost is small. By doing so, it is possible to input the amount of heat of melting according to the amount of frost formed, and it is possible to perform defrosting efficiently.

[0053] Embodiment 3 Hereinafter, the third embodiment will be described, but explanations of parts that overlap with the first and second embodiments will be omitted, and the same parts as or corresponding parts to the first and second embodiments will be given the same reference numerals.

[0054] Fig. 11 is a diagram showing temperature characteristics of a refrigerant when the refrigerant flows in series through the outdoor heat exchanger 30 on the upstream side and the outdoor heat exchanger 30 on the downstream side of the refrigeration cycle apparatus according to embodiment 3. Fig. 12 is a diagram showing temperature characteristics of a refrigerant when the refrigerant flows in parallel through the outdoor heat exchangers 30 of the refrigeration cycle apparatus according to embodiment 3. Note that the horizontal axis of Fig. 11 and Fig. 12 shows the dryness fraction, and the vertical axis shows the temperature.

[0055] The refrigerant circulating through the refrigerant circuit 100 is a mixed refrigerant obtained by mixing refrigerants having different boiling points from among R410A, R454A, R454B, R454C, and R466A.

[0056] In addition, when a mixed refrigerant obtained by mixing refrigerants having different boiling points is used, if the outdoor heat exchanger 30 is made to function as a condenser as in the defrost operation, the temperature of the two-phase region decreases as condensation proceeds from a saturated gas to a saturated liquid due to a temperature gradient, as shown in Figures 11 and 12. In the third embodiment, the defrost operation is performed by flowing the refrigerant in series through the outdoor heat exchanger 30 on the upstream side and the outdoor heat exchanger 30 on the downstream side. Therefore, the change in dryness fraction at the inlet and outlet of each outdoor heat exchanger 30 is smaller, and the change in temperature at the inlet and outlet of the outdoor heat exchanger 30 is smaller (see Figure 11) than when the defrost operation is performed by flowing the refrigerant in parallel through each outdoor heat exchanger 30 (see Figure 12).

[0057] In this way, the refrigerant circulating through the refrigerant circuit 100 is a mixed refrigerant made by mixing refrigerants with different boiling points. This reduces the change in dryness fraction at the inlet and outlet of each outdoor heat exchanger 30 and the change in temperature at the inlet and outlet of the outdoor heat exchanger 30, making it possible to melt frost evenly and reducing the amount of frost that remains unmelted.

[0058] In addition, the use of a mixed refrigerant with a low GWP value can reduce the environmental impact. In addition, the outdoor heat exchanger 30 is a corrugated fin tube type using flat tubes 34, so the amount of refrigerant used can be reduced.

[0059] As described above, in the refrigeration cycle device according to the third embodiment, the refrigerant is a mixed refrigerant obtained by mixing refrigerants having different boiling points.

[0060] According to the refrigeration cycle device of embodiment 3, the change in dryness at the inlet and outlet of each outdoor heat exchanger 30 is small, and the change in temperature at the inlet and outlet of the outdoor heat exchanger 30 is also small, making it possible to melt the frost evenly and suppressing the remaining frost from remaining unmelted. [Explanation of symbols]

[0061] 10 outdoor unit, 11 compressor, 12 flow switching device, 13 flow control valve, 13a flow control valve, 13b flow control valve, 13c flow control valve, 14 opening and closing valve, 15 check valve, 16 accumulator, 17 temperature sensor, 20 indoor unit, 21 throttling device, 22 indoor heat exchanger, 30 outdoor heat exchanger, 30a outdoor heat exchanger, 30b outdoor heat exchanger, 30c outdoor heat exchanger, 30d outdoor heat exchanger, 31 distribution header, 31A distribution header, 31B distribution header, 32 refrigerant inlet and outlet pipe, 32A refrigerant inlet and outlet pipe, 32B refrigerant inlet and outlet pipe, 33 folded header, 34 flat tube, 35 corrugated fin, 40 housing, 41 air outlet, 42 outdoor fan, 43 service panel, 100 Refrigerant circuit, 101 pipe, 101a pipe, 101a1 pipe, 101a2 pipe.

Claims

1. The present invention relates to a refrigerant circuit in which a compressor, a flow switching device, an indoor heat exchanger, a throttling device, a plurality of flow control valves, and a plurality of outdoor heat exchangers are connected by piping, and in which a refrigerant circulates; The plurality of outdoor heat exchangers are arranged in one outdoor unit, The outdoor unit is a top-flow type in which an outdoor fan is provided at the top, The outdoor heat exchangers are three in number, and are disposed on the left side, the right side, and the rear side of the outdoor unit, respectively; The refrigerant circuit includes: During heating operation, the refrigerant flows in parallel through each of the outdoor heat exchangers, During cooling operation and defrost operation, the refrigerant flows in series through some of the outdoor heat exchangers on the upstream side and the remaining some of the outdoor heat exchangers on the downstream side, The outdoor heat exchanger on the upstream side is the outdoor heat exchanger arranged on the left side surface and the right side surface of the outdoor unit, The downstream outdoor heat exchanger is the outdoor heat exchanger disposed on the rear surface of the outdoor unit, A temperature sensor is provided only on the piping on the outlet side of the outdoor heat exchanger arranged on the rear surface of the outdoor unit, which is downstream during cooling operation and defrost operation. Refrigeration cycle equipment.

2. The temperature sensor is provided between one of the outdoor heat exchangers and one of the flow rate control valves, the temperature sensor being downstream during cooling operation and defrost operation. The refrigeration cycle device according to claim 1.

3. Each of the plurality of outdoor heat exchangers is A pair of headers arranged vertically, one above the other, A flat tube group is disposed between the pair of headers and perpendicular to the pair of headers, the flat tube group being composed of a plurality of flat tubes whose flat surfaces are opposed to each other so as to be parallel to each other; and a corrugated fin disposed between two adjacent flat tubes and joined to the flat surfaces of the flat tubes. The refrigeration cycle apparatus according to claim 1 or 2.

4. The area of ​​the flat tube group of the outdoor heat exchanger arranged on the left side surface of the outdoor unit is the same as the area of ​​the flat tube group of the outdoor heat exchanger arranged on the right side surface of the outdoor unit, and The sum of the area of ​​the flat tube group of the outdoor heat exchanger arranged on the left side surface of the outdoor unit and the area of ​​the flat tube group of the outdoor heat exchanger arranged on the right side surface of the outdoor unit is larger than the area of ​​the flat tube group of the outdoor heat exchanger arranged on the rear surface of the outdoor unit. The refrigeration cycle device according to claim 3.

5. The refrigerant is a mixed refrigerant having different boiling points. The refrigeration cycle device according to any one of claims 1 to 4.

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