Outdoor unit of air conditioner

Abstract

The present invention provides an outdoor unit for an air conditioner that reduces pressure loss when used as an evaporator. While maintaining low-cost performance despite the influence of water head generated by the heat exchanger's wind speed distribution and height, it achieves high heating capacity and improved cooling performance. The heat exchanger comprises three rows of heat exchangers, each at least 1 meter high and arranged along the airflow direction. The first row of heat exchangers on the upwind side of the heat exchangers is configured with U-shaped heat transfer tubes arranged overlapping in the stage direction. The two rows on the leeward side are configured with U-shaped heat transfer tubes spanning the second and third rows of heat exchangers. The third row of heat exchangers on the upper heat exchanger is connected to a gas header. The number of refrigerant channels connected to the gas header is greater than the total number of heat exchanger stages / 2, and the number of stages is equal to the number of refrigerant channels connected to the gas header. The first row of heat exchangers on the lower heat exchanger is connected to a liquid refrigerant distributor. The U-shaped heat transfer tubes of the third row of heat exchangers on the lower heat exchanger are connected to the U-shaped heat transfer tubes of the first row of heat exchangers on the upper heat exchanger via channel connecting tubes.

Description

Technical Field

[0001] The present invention relates to an outdoor unit of an air conditioner, and more particularly to a top-flow type outdoor unit having an air supply fan mounted on an upper portion of a heat exchanger. Background Art

[0002] An air conditioner that heats and cools a room consists of an outdoor unit installed outdoors and an indoor unit installed indoors. Each indoor unit and outdoor unit include a heat exchanger that exchanges heat between air and refrigerant, a blower fan that flows air through the heat exchanger, and refrigerant piping connecting the outdoor and indoor units. The outdoor unit's heat exchanger absorbs heat from the outside air during heating operation, heating the room, and releases heat to the outside air during cooling operation, cooling the room.

[0003] However, in buildings such as commercial buildings, for example, VRF (Variable Refrigerant Flow) air conditioning systems are used. These systems include one or more outdoor units and multiple indoor units connected to the outdoor units via refrigerant piping. Such systems are known as "multi-split air conditioning systems."

[0004] Outdoor units used in VRF air conditioners are often top-flow outdoor units with a blower fan mounted above the heat exchanger. International Publication No. 2014 / 199501 (Patent Document 1) describes a heat exchanger using flat tubes as heat transfer pipes as an example of a top-flow outdoor unit.

[0005] The outdoor unit disclosed in Patent Document 1 includes a heat exchanger having a plurality of flat heat transfer tubes arranged in parallel, serving as at least a condenser in a refrigeration cycle; and a blower fan for generating a flow of air through the heat exchanger at a predetermined velocity distribution. The term "refrigerant passage" used below refers to the flow path of the refrigerant.

[0006] In Patent Document 1, a heat exchanger serving as a condenser exchanges heat between a refrigerant flowing through a heat transfer tube and air, releasing the refrigerant's heat into the air. The heat exchanger includes multiple refrigerant passages formed from one or more heat transfer tubes. The multiple refrigerant passages include: a plurality of first refrigerant passages into which a gas refrigerant flows and out as a two-phase refrigerant; and a plurality of second refrigerant passages into which the two-phase refrigerant flowing out of the plurality of first refrigerant passages flows and out as a subcooled liquid refrigerant.

[0007] The second refrigerant passages are located in regions with lower air velocity than the first refrigerant passages. The first refrigerant passages are located in regions with different air velocity, and the second refrigerant passages are also located in regions with different air velocity.

[0008] The plurality of first refrigerant passages and the plurality of second refrigerant passages are configured such that correspondence is established with each other in sequence among the first refrigerant passages and the second refrigerant passages, starting from the refrigerant passages arranged in the area with higher air velocity, and the outlet sides of the plurality of first refrigerant passages are respectively connected to the inlet sides of the plurality of second refrigerant passages with which the correspondence is established.

[0009] Furthermore, in an air conditioner using a heat transfer pipe formed by bending a round tube into a U-shape as an outdoor heat exchanger, Japanese Patent Application Laid-Open No. 2014-126322 (Patent Document 2) describes an outdoor heat exchanger for an air conditioner that increases the number of refrigerant passages to improve air conditioning performance.

[0010] The air conditioner described in Patent Document 2 connects an outdoor unit (including a compressor, an outdoor heat exchanger, and an outdoor expansion valve) to an indoor unit via liquid and gas connecting pipes. The outdoor heat exchanger includes a plurality of plate-shaped heat exchange fins, a plurality of heat transfer pipes, a liquid refrigerant distributor that connects the heat transfer pipes into multiple paths, and a gas refrigerant distributor.

[0011] Furthermore, the number of refrigerant paths on the gas refrigerant distributor side is more than double the number of refrigerant paths on the liquid refrigerant distributor side, resulting in a single outdoor heat exchanger being divided into multiple units. Each of the multiple outdoor heat exchangers comprises a plurality of plate-shaped heat exchange fins, a plurality of heat transfer tubes orthogonal to the plate-shaped heat exchange fins, a liquid refrigerant distributor that integrates the heat transfer tubes into multiple paths, and a gas refrigerant distributor. Furthermore, the number of refrigerant paths on the liquid refrigerant distributor side of the combined outdoor heat exchangers is greater than the number of heat transfer tube stages in the pre-division outdoor heat exchanger / four.

[0012] Prior art literature

[0013] Patent Literature

[0014] Patent Document 1: International Publication No. 2014 / 199501

[0015] Patent Document 2: Japanese Patent Application Laid-Open No. 2014-126322 Summary of the Invention

[0016] Problems to be solved by the invention

[0017] Among air-conditioning apparatuses, large-scale air-conditioning apparatuses used in buildings such as commercial buildings are required to have improved cooling and heating capabilities per outdoor unit.

[0018] To improve heating capacity when a heat exchanger functions as an evaporator during heating operation, a large amount of liquid refrigerant must flow through the heat exchanger to evaporate. The number of refrigerant channels within a heat exchanger refers to the number of channels through which the refrigerant branches and flows. If this number of channels is too small, the flow rate within the channels will be excessively high when the liquid refrigerant vaporizes, resulting in increased internal pressure loss.

[0019] This internal pressure loss becomes a major factor in the formation of an undesirable temperature distribution within the heat exchanger, leading to a decrease in the energy efficiency of the air conditioner. Therefore, in order to improve the heating capacity, it is necessary to increase the number of refrigerant passages.

[0020] On the other hand, when a heat exchanger with increased refrigerant passages is used as a condenser during cooling operation, condensation of the gas refrigerant progresses and the ratio of liquid refrigerant increases. In this case, if the number of refrigerant passages is large, the flow rate of the liquid refrigerant decreases excessively, thereby reducing heat exchange performance. Therefore, in order to improve heat exchange performance (cooling performance) during cooling operation, it is necessary to reduce the number of refrigerant passages on the liquid refrigerant distributor side of the heat exchanger in advance.

[0021] Furthermore, in top-flow outdoor units with heat exchangers exceeding 1 meter in height, when the heat exchanger is used as a condenser during cooling, the height difference between the liquid outlet of the uppermost refrigerant passage and the lowermost refrigerant passage is often close to 1 meter. In such cases, a pressure corresponding to the height of the liquid refrigerant, approaching 10 kPa, acts on the liquid outlet of the lowermost refrigerant passage.

[0022] However, when used as a condenser, the pressure difference between the gas and liquid sides is typically small, sometimes even below 10 kPa, especially when a large number of refrigerant channels are present. In these situations, refrigerant may not flow through the refrigerant channels in the lower portion of the heat exchanger, where the liquid outlet is pressurized. These refrigerant channels, where refrigerant does not flow, essentially do not exchange heat, wasting heat transfer area in these areas, which in turn reduces heat exchange performance (refrigeration performance).

[0023] Furthermore, in a top-flow outdoor unit, the air supply fan is located above the outdoor unit, and the heat exchanger is positioned perpendicular to the installation surface (e.g., the ground or the roof of a building) on ​​the side of the outdoor unit. Consequently, the wind speed tends to be higher in the upper portion of the heat exchanger, closer to the air supply fan, and lower in the lower portion, farther from the fan.

[0024] Therefore, the heat exchange capacity of the lower part of the heat exchanger is less than that of the upper part. Therefore, the refrigerant distribution amount needs to be adjusted according to the heat exchange capacity using a liquid refrigerant distributor and pressure loss devices such as narrow-diameter tubes, which increases the manufacturing cost accordingly.

[0025] In addition, in the air conditioning device of Patent Document 1, by arranging the first refrigerant passage in a relatively high wind speed area and arranging the second refrigerant passage in a relatively low wind speed area, the proportion of the liquid phase in the heat transfer pipe can be reduced, thereby improving heat exchange efficiency.

[0026] However, because the heat exchanger described in Patent Document 1 utilizes flat tubes, the internal flow path is narrow. This results in significant pressure loss, particularly when used as an evaporator, hindering improvements in heating capacity. Furthermore, flat tubes present challenges such as complex structure and increased manufacturing costs.

[0027] On the other hand, in the heat exchanger using round tubes in Patent Document 2, the number of passages on the liquid refrigerant distributor side of the outdoor heat exchangers divided into multiple groups is greater than the number of heat transfer tube stages of the outdoor heat exchanger before division / 4.

[0028] However, the air conditioner described in Patent Document 2 requires the heat exchanger to be divided into two parts. Therefore, if the heat exchanger cannot be divided into two parts, or if the heating capacity is to be further improved based on the state of the heat exchanger being divided into two parts, the number of refrigerant channels cannot be increased, and the heating capacity cannot be improved.

[0029] An object of the present invention is to provide an outdoor unit of an air conditioner that can achieve high heating capacity and improved cooling performance at low cost while being affected by the wind speed distribution and water head generated by the height of the heat exchanger.

[0030] Solutions to Problems

[0031] The present invention provides an outdoor unit of an air conditioner, which comprises at least a compressor, an air supply fan, and a heat exchanger, and is characterized in that:

[0032] The air supply fan is mounted on the upper part of the heat exchanger.

[0033] The heat exchanger is composed of an upper heat exchanger and a lower heat exchanger, each heat exchanger being composed of a U-shaped heat transfer pipe formed by a round pipe bent into a U shape, a heat transfer fin, a liquid refrigerant distributor, a gas header, and a passage connection pipe connecting the ends of the U-shaped heat transfer pipe.

[0034] The heat exchanger consists of three rows of heat exchange parts arranged along the direction of air flow.

[0035] The first row of heat exchangers on the upwind side of the heat exchanger is configured with U-shaped heat pipes overlapping in the level direction, and the two rows on the downwind side are configured with U-shaped heat pipes spanning the second and third rows of heat exchangers.

[0036] The ends of the U-shaped heat transfer tubes of the third row of heat exchangers on the upper side are connected to the gas header. The number of refrigerant paths connected to the gas header is greater than the total number of heat exchanger stages / 2. The number of stages on the upper side heat exchanger is the same as the number of refrigerant paths connected to the gas header.

[0037] The ends of the U-shaped heat pipes of the first row of heat exchangers in the lower side heat exchanger are connected to the liquid refrigerant distributor, and the U-shaped heat pipes of the third row of heat exchangers in the lower side heat exchanger are connected to the U-shaped heat pipes of the first row of heat exchangers in the upper side heat exchanger via passage connecting pipes.

[0038] The effects of the invention are as follows.

[0039] According to the present invention, it is possible to achieve high heating capacity and improved cooling performance at low cost while taking into account the influence of the water head caused by the wind speed distribution and the height of the heat exchanger. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 This is a perspective view of the appearance of an outdoor unit of an air-conditioning apparatus to which the present invention is applied.

[0041] Figure 2 It shows Figure 1 The external perspective view of the internal structure of the outdoor unit is shown.

[0042] Figure 3 It is a structural diagram showing a refrigeration cycle of an air-conditioning apparatus.

[0043] Figure 4 This is a three-dimensional diagram of the appearance of an existing heat exchanger.

[0044] Figure 5 This is an external perspective view for explaining a conventional method of manufacturing a heat exchanger.

[0045] Figure 6 This is a structural diagram for explaining a refrigerant passage in a conventional heat exchanger.

[0046] Figure 7 This is a structural diagram for explaining a refrigerant passage in another conventional heat exchanger.

[0047] Figure 8 This is a perspective view of the appearance of the heat exchanger according to the first embodiment of the present invention, viewed from one side.

[0048] Figure 9 This is a structural diagram of a refrigerant passage for explaining the first embodiment of the present invention.

[0049] Figure 10 This is a perspective view of the appearance of the heat exchanger according to the first embodiment of the present invention, viewed from another side.

[0050] Figure 11 This is a structural diagram of a refrigerant passage for explaining the second embodiment of the present invention.

[0051] Figure 12 This is a structural diagram of a refrigerant passage for explaining a third embodiment of the present invention. DETAILED DESCRIPTION

[0052] Hereinafter, embodiments of the present invention will be described in detail using the drawings. However, the present invention is not limited to the following embodiments, and various modifications and application examples are included within the technical concept of the present invention.

[0053] First, use Figure 1 The following describes an overview of an outdoor unit to which the present invention applies. This outdoor unit is a top-flow type with a fan located in the upper portion of the housing. To maintain a compact installation footprint and achieve high cooling and heating capabilities, the outdoor unit is over 1 meter tall, and the heat exchanger is also over 1 meter tall.

[0054] In addition, if Figure 1 As shown, the outdoor unit to which the present invention is applied is composed of two blower fans 13, two bell mouths 16 formed therewith, and two outdoor heat exchangers 12. Furthermore, these are housed in a housing composed of a front panel 15 and the like.

[0055] Figure 2 Shown from Figure 1 The outdoor unit shown is a perspective view with the fan, bell, and front panel 15 removed, revealing the interior. Inside the outdoor unit, a compressor 10, a refrigerant tank 11, an accumulator 14, a control panel 17, and other components are located. The outdoor unit is mounted on a bottom mounting plate 18. The control panel 17 houses inputs for sensors installed in the outdoor unit and electrical components that control the operation of the compressor 10 and the air blower fan 13. The refrigerant tank 11 is installed midway through the refrigeration cycle to absorb the difference in refrigerant volume required within the cycle between cooling and heating operations.

[0056] Figure 3This section outlines the refrigeration cycle in a VRF air conditioning system, specifically describing the refrigeration cycle during heating operation. High-temperature, high-pressure gas refrigerant discharged from the compressor 10 flows through the refrigerant pipe 9 and the four-way valve 19 to the gas-side shutoff valve. From there, the indoor unit 103 is connected to the gas-side shutoff valve via the gas refrigerant pipe 101. The gas refrigerant flowing out of the gas-side shutoff valve flows to the indoor heat exchanger 104 within the indoor unit 103. Indoor units 103 are installed in two rooms 300. Of course, they can be installed in more rooms.

[0057] In the indoor heat exchanger 104, air is circulated by the indoor air supply fan 105, which absorbs heat from the refrigerant and is then supplied indoors. Inside the indoor heat exchanger 104, the refrigerant is cooled and liquefied. The liquefied refrigerant flows through the liquid refrigerant pipe 102 to the liquid-side shutoff valve. The refrigerant flowing from the liquid-side shutoff valve into the outdoor unit 100 is decompressed by the outdoor expansion valve 20 housed within the outdoor unit 100, becoming a low-temperature, low-pressure gas-liquid two-phase state. The refrigerant then flows through the refrigerant tank and other components to the outdoor heat exchanger 12.

[0058] Outdoor air flows through the outdoor heat exchanger 12 by the outdoor blower fan 13 , and the refrigerant is decompressed to a temperature lower than that of the outdoor air flowing through the outdoor heat exchanger 12 .

[0059] The gaseous refrigerant evaporates and vaporizes in the outdoor heat exchanger 12. It then passes through the four-way valve 19 and returns to the compressor 10 via the accumulator 14. It is then compressed again into a high-temperature, high-pressure gas by the compression action of the compressor 10. This repetition of the above-described process allows continued heating operation. During cooling operation, the connection at the four-way valve 19 is switched so that the discharge pipe from the compressor 10 is connected to the outdoor heat exchanger 12 and the gas-side shutoff valve is connected to the accumulator 14.

[0060] As a result, the refrigerant flows in the outdoor heat exchanger 12 and the indoor heat exchanger 104. Furthermore, the gaseous refrigerant condenses and liquefies in the outdoor heat exchanger 12, while the liquid refrigerant evaporates and vaporizes in the indoor heat exchanger 104. By repeating this process, cooling operation can be continued.

[0061] Figure 4 The structure of a heat exchanger using conventional round heat pipes is shown. Figure 4 As shown, the heat exchanger is composed of a U-shaped heat transfer pipe 22, a circular tube bent into a U-shape, and plate-shaped heat exchange fins 21. The heat exchanger is arranged in three rows, with the first row of heat exchange sections 28, the second row of heat exchange sections 29, and the third row of heat exchange sections 30 arranged longitudinally along the wind flow from the upwind side.

[0062] Figure 5 Shows the assembled structure of the heat exchanger. Figure 4 The heat exchanger shown is manufactured by inserting U-shaped heat transfer tubes 22 into heat transfer fins 21 stacked at equal intervals. Typically, after inserting the U-shaped heat transfer tubes 22 into the heat transfer fins 21, a pipe expansion machine is inserted from the end of the U-shaped heat transfer tube 22 to expand the U-shaped heat transfer tube 22 from the inside, thereby ensuring close contact between the heat transfer fins 21 and the U-shaped heat transfer tube 22. In addition to mechanical pipe expansion, there are also expansion methods using hydraulic pressure.

[0063] In the conventional heat exchanger, a configuration in which U-shaped heat transfer pipes 22 are arranged vertically in each row is used (see Figure 5 ) so that the heat exchanger assembly process of inserting the U-shaped heat conduction pipe 22 into the heat exchange fin 21 can be performed in each column.

[0064] Figure 6 2 shows a conventional refrigerant passage (refrigerant flow path) formed by a U-shaped heat transfer pipe 22. Figure 6 The horizontal direction in the figure is set as the column direction, and counting from the left is the first column heat exchange unit 28, the second column heat exchange unit 29, and the third column heat exchange unit 30. Figure 6 The longitudinal direction in the figure is set as the level direction, and the heat pipes are counted as the first level or the second level according to the number of the heat pipes. Figure 6 The structure shown is a three-row, 12-stage heat exchanger. Conventional heat exchangers are constructed by arranging U-shaped heat transfer tubes 22 in the stage direction and arranging them in three rows.

[0065] Figure 6 The black arrows in the figure indicate the flow of refrigerant. During heating operation, the two-phase flow exiting the expansion valve is distributed by a liquid refrigerant distributor (not shown) to the liquid-side refrigerant inlets and outlets 25 of the heat exchanger. The flow then follows the arrows in the figure, flowing from the third row of heat exchange sections 30 of the heat exchanger into the gas header 24. The refrigerant, after merging in the gas header 24, flows toward the four-way valve.

[0066] In air conditioning systems, large amounts of refrigerant must flow through the heat exchanger to achieve the high air conditioning capacity during both cooling and heating operations. During heating operation, the outdoor unit's heat exchanger functions as an evaporator, vaporizing a large amount of liquid refrigerant. This phase transition from liquid to gas dramatically increases the volume per unit mass of refrigerant, increasing the refrigerant flow rate within the heat transfer pipes within the heat exchanger and causing significant pressure loss. This pressure loss also affects the refrigerant's temperature distribution within the heat exchanger, reducing the heat exchange performance of the heat exchanger.

[0067] Therefore, in the existing heat exchanger equipped with a model corresponding to a higher heating capacity, a method of using the maximum number of divisions of the U-shaped heat transfer pipe is adopted. Figure 6The refrigerant passage. Figure 6 In the refrigerant path structure shown, the number of refrigerant flow paths in the heat exchanger, i.e., the number of refrigerant paths, is increased as much as possible, the piping length of one refrigerant path is shortened, and the amount of refrigerant flowing into one refrigerant path is reduced, thereby reducing pressure loss.

[0068] Especially in air-conditioning devices with higher air conditioning capabilities, as shown in Patent Document 2, by dividing the heat exchanger of the outdoor unit, the amount of refrigerant flowing to one heat exchanger can be reduced, and the width of the heat exchanger can be shortened. Therefore, the flow path length of one circle of the U-shaped heat pipe becomes shorter, and of course the pressure loss of the refrigerant can also be reduced.

[0069] Here, in Figure 6 In the conventional refrigerant path structure shown, the heat exchanger uses a U-shaped heat transfer tube arrayed in each row along the level direction. This reduces manufacturing costs because identical heat exchangers can be manufactured and assembled in each row. On the other hand, the heat exchange capacity is greatest in the first row on the upwind side, while less in the second and third rows on the downwind side.

[0070] Therefore, without using Figure 6 In the case of a structure such as the existing refrigerant passage structure shown in which a refrigerant passage is connected from the first column of heat exchange sections 28 to the third column of heat exchange sections 30, for example, if a passage is provided that divides the refrigerant after passing through the first column of heat exchange sections 28 into two, with one side flowing to the U-shaped heat pipe of the second column of heat exchange sections 29 and the other side flowing to the U-shaped heat pipe of the third column of heat exchange sections 30, the heat exchange amount that can be performed by the second column of heat exchange sections 29 is greater than the heat exchange amount of the third column of heat exchange sections 30, and the refrigerant distribution must be adjusted accordingly.

[0071] In other words, a pressure-loss device, such as a narrow-diameter tube, must be installed at the connection between the first and third heat exchanger rows 28 and 30 to prevent refrigerant from flowing into the U-shaped heat transfer tubes of the third heat exchanger row 30. Furthermore, if this distribution is not optimal, performance will be reduced.

[0072] Furthermore, similarly, in a structure in which the liquid side refrigerant inlet and outlet 25 is provided in the second column of heat exchange sections 29 or the third column of heat exchange sections 30 without increasing the number of passages, it is also difficult to flow an appropriate amount of refrigerant after the second column of heat exchange sections 29 because the air temperature changes according to the amount of heat exchange in the first column of heat exchange sections 28, thereby making it difficult to improve performance.

[0073] Furthermore, during cooling operation, if the first row of heat exchangers 28 does not have the liquid-side refrigerant inlet and outlet 25, the cooling air temperature rises due to heat exchange in the first row of heat exchangers 28. Therefore, compared to a case where the first row of heat exchangers 28 has the liquid-side refrigerant inlet and outlet 25, the amount of subcooling of the condensed liquid refrigerant cannot be obtained. Generally, if the amount of subcooling cannot be obtained, performance tends to deteriorate.

[0074] In addition, in this Figure 6 In the conventional refrigerant path structure shown, when used as a condenser during cooling, a height difference occurs between the top and bottom refrigerant paths of the heat exchanger. Here, the outer diameter of the U-shaped heat transfer tube 22 is 5 mm to 8 mm, while the step pitch is between 15 mm and 30 mm.

[0075] Therefore, if the step spacing is set to 20 mm, then Figure 6 The height of the heat exchanger is about 240mm. In fact, the number of heat exchanger stages of the top-flow outdoor unit corresponding to the higher heating capacity is close to 50, and the height is also over 1m.

[0076] The attached figure shows a 12-stage heat exchanger, but in reality, the refrigerant passages are arranged at the same ratio in the direction of the number of stages (upward). If the number of stages is 50, then Figure 6 The existing refrigerant passages shown mean that the number of refrigerant passages is 25.

[0077] For example, the height difference between the liquid-side refrigerant inlet and outlet 25 of the uppermost passage and the liquid-side refrigerant inlet and outlet 25 of the lowermost passage of the heat exchanger is 1 meter. Furthermore, as refrigerants used in recent air conditioners, there are refrigerants such as "R410A" and "R32". Regarding their liquid density at 2.2 MPa and 35°C, "R410A" is 1006 kg / m 3 "R32" is 917kg / m 3 Therefore, even with the relatively low density of R32 refrigerant, a water head of at least 8.9 kPa is applied to the liquid refrigerant inlet and outlet 25 at the lower side of the heat exchanger. When the heat exchanger is used as a condenser, the pressure loss between the gas header and the liquid refrigerant distributor is often around 10 kPa.

[0078] Therefore, the upper refrigerant passage not subjected to the water head generates a pressure difference of 10 kPa due to the pressure loss of the refrigerant alone, but the lower refrigerant passage subjected to the water head needs to add the pressure loss of the refrigerant flow to a value of 10 kPa.

[0079] In other words, refrigerant passages subject to hydraulic head experience a corresponding reduction in refrigerant circulation volume, minimizing pressure losses during refrigerant flow and achieving a balance. Furthermore, in heat exchangers with higher heights, where the hydraulic head alone exceeds 10 kPa, refrigerant can hardly flow. This lack of refrigerant flow means that heat exchange is not taking place in these refrigerant passages, preventing efficient use of heat transfer area and resulting in reduced performance.

[0080] And, as Figure 1 As shown in Figure 1, in a top-flow outdoor unit with a high heat exchanger, the air velocity flowing into the heat exchanger differs between the upper and lower portions. Specifically, the air velocity is higher on the upper side of the heat exchanger, closer to the outdoor air supply fan, and lower on the lower side of the heat exchanger, farther from the outdoor air supply fan.

[0081] Therefore, in the upper part where the wind speed is faster, the heat exchange amount is greater, so a large amount of refrigerant needs to flow, and in the lower part where the wind speed is slower, the amount of heat exchange refrigerant needs to be reduced. Figure 6 In the conventional refrigerant passage shown, narrow tubes of different lengths are provided between the liquid refrigerant inlet and outlet 25 and the liquid refrigerant distributor connected thereto, to adjust the amount of refrigerant flowing into each refrigerant passage, particularly when used as an evaporator.

[0082] However, these narrow tubes are required in all refrigerant paths. In refrigerant paths where the refrigerant flow rate is to be reduced, narrow tubes of more than one meter in length are sometimes required, which increases manufacturing costs. Furthermore, designing refrigerant quantity adjustments using these narrow tubes requires accurate knowledge of the pressure loss of the gas-liquid two-layer flow, making this difficult.

[0083] On the other hand, in models that do not require high heating capacity, Figure 7 That is, in a refrigerant path structure similar to that of Patent Document 1, the heat exchanger is divided into an upper portion and a lower portion, and during heating operation, the refrigerant flowing into the lower heat exchanger passes through the path connecting pipe 26, flows in the upper heat exchanger, and flows out to the gas header.

[0084] In this configuration, when the outdoor heat exchanger is used as a condenser during cooling operation, the number of passages in the liquid-side refrigerant inlet and outlet 25 can be reduced. While reducing the number of passages in the liquid-side refrigerant inlet and outlet 25 can reduce the velocity of the two-phase flow as refrigerant condensation progresses and the liquid phase increases, this can be suppressed. At least compared to a larger number of refrigerant passages, a smaller number of refrigerant passages increases the refrigerant flow velocity, thus increasing the thermal conductivity on the refrigerant side and making it easier to achieve subcooling.

[0085] Furthermore, as mentioned above, it is known that the wind speed is faster the closer to the upper part of the heat exchanger, and the wind speed is slower the closer to the lower part. Figure 7 The heat exchanger shown is divided into an upper heat exchanger and a lower heat exchanger. Since the refrigerant can pass through both the upper and lower heat exchangers, the difference in heat exchange amount between the refrigerant paths becomes smaller.

[0086] exist Figure 6 In the refrigerant path shown, the heat exchange amount differs greatly between the lower heat exchanger with a slower wind speed and the upper heat exchanger with a faster wind speed. Figure 7 In this refrigerant path structure, a single refrigerant path passes through both the lower heat exchanger (where air velocity is slower) and the upper heat exchanger (where air velocity is faster). This reduces the difference in the total refrigerant path air volume. This makes it easier to adjust the refrigerant distribution, reducing the manufacturing cost associated with distribution adjustments such as installing narrow-diameter tubes.

[0087] However, in Figure 7 In the structure of the refrigerant passage shown, it is impossible to make the number of refrigerant passages in the heat exchanger larger than Figure 6 The number of refrigerant passages shown is large, and the heating capacity cannot be improved, particularly during heating operation.

[0088] Example 1

[0089] Based on such background, in the first embodiment of the present invention, the object is to provide an outdoor unit of an air-conditioning device, which can reduce the pressure loss when the heat exchanger is used as an evaporator, and can achieve higher heating capacity and improved cooling performance at low cost under the influence of the wind speed distribution of the heat exchanger and the water head generated by the height of the heat exchanger.

[0090] Figure 8 The structure of the heat exchanger used in this embodiment is shown. In this embodiment, in the first row of heat exchange sections 28 on the upwind side of the heat exchanger, U-shaped heat transfer tubes 22 are arranged in the step direction (height direction). In the second and third rows of heat exchange sections 29 and 30 on the leeward side, the U-shaped heat transfer tubes 22 are arranged so as to span the second and third rows of heat exchange sections 29 and 30. The U-shaped heat transfer tubes 22 are bent into a U-shape, with the bent portion 22B exposed on one side of the outdoor heat exchanger 12 parallel to the air flow, and the end portion 22E for the refrigerant to flow in and out is exposed on the other side of the outdoor heat exchanger 12 parallel to the air flow.

[0091] Figure 9The structure of the refrigerant pathway in this embodiment is shown. The outdoor heat exchanger 12 consists of an upper heat exchanger 12U and a lower heat exchanger 12B. The upper heat exchanger 12U has more stages than the lower heat exchanger 12B. Considering the number of stages in the third row of heat exchange units 30, the number of stages is doubled. Furthermore, the refrigerant pathway formed by the U-shaped heat pipes 22 is staggered when viewed along the air flow direction. This increases the spacing between the heat pipes, prevents airflow acceleration, and reduces pressure loss.

[0092] When the heat exchanger of this embodiment is set to heating operation, that is, used as an evaporator, first, the two-phase flow after passing through the expansion valve is distributed by the liquid refrigerant distributor, and then only a small amount passes through the narrow diameter tube for adjusting the distribution amount. Figure 9 The refrigerant flows into the two liquid-side refrigerant inlets and outlets 25.

[0093] The refrigerant flowing in from two places rises in each U-shaped heat transfer pipe of the first row of heat exchanger 28, and is distributed at the downwind side thereof and flows into two cross-row U-shaped heat transfer pipes arranged across the second row of heat exchanger 29 and the third row of heat exchanger 30. When branching from the first row of heat exchanger 28 to the second row of heat exchanger 29, a three-pronged joint 23 (see Figure 10 ) to branch.

[0094] The refrigerant flowing in from the two locations flows through the four refrigerant paths of the second row heat exchanger 29 and the third row heat exchanger 30 of the lower heat exchanger 12B. The four refrigerant paths pass through the path connecting pipes 26 and reach the upper heat exchanger 12U.

[0095] Then, the refrigerant having passed through the four refrigerant passages of the first row of heat exchangers 28 of the upper side heat exchanger 12U flows between the first row of heat exchangers 28 and the second row of heat exchangers 29 and passes through the three-way junction 23 (see Figure 10 ) is divided into eight refrigerant paths after being branched into two. Then, the vaporized refrigerant finally flows into the gas header 24 from the eighth stage of the third row of heat exchange units 30 of the upper side heat exchanger 12U in the eight refrigerant paths.

[0096] Furthermore, the connection portion (liquid-side refrigerant inlet and outlet 25) to the liquid refrigerant distributor in the lower heat exchanger 12B is located at the gravitationally downward end of the U-shaped heat transfer tubes arranged in the stage direction of the first row of heat exchange sections 28. Thus, when functioning as an evaporator, the refrigerant flowing in through the liquid-side refrigerant inlet and outlet 25 rises and flows into the upper stage of the same U-shaped heat transfer tube. On the other hand, when functioning as a condenser, the flow is reversed.

[0097] Figure 10 Shown assembled with Figure 9A perspective view of the heat exchanger with refrigerant piping is shown. The refrigerant piping consists of a U-shaped heat transfer pipe 22, a three-pronged joint 23, a gas header 24, and a flow connection pipe 26. Furthermore, the U-shaped heat transfer pipe 22, three-pronged joint 23, and flow connection pipe 26 are formed into circular tubular shapes, thereby reducing pressure loss when the heat exchanger is used as an evaporator.

[0098] Here, the three-pronged joint 23, the gas manifold 24, the end 22E of the U-shaped heat pipe 22 serving as the liquid side refrigerant inlet and outlet 25, and the passage connecting pipe 26 are concentratedly arranged on one side of the surface of the heat exchanger parallel to the flow of air, and the U-shaped bend 22B of the U-shaped heat pipe 22 is arranged on the other side of the surface of the heat exchanger parallel to the flow of air.

[0099] like Figure 9 As shown, by combining the first row of heat exchange sections 28 in which U-shaped heat transfer tubes 22 are arranged in the level direction, the second row of heat exchange sections 29 and the third row of heat exchange sections 30 in which cross-row U-shaped heat transfer tubes 22 are arranged in the level direction, when the refrigerant flows from the first row of heat exchange sections 28 to the second row of heat exchange sections 29, the refrigerant path can be easily divided and increased using only the three-pronged joint 23.

[0100] In addition, the heat exchanger is divided into an upper side heat exchanger 12U and a lower side heat exchanger 12B, and the refrigerant passes through each heat exchanger. Therefore, it is only divided into two branches from the first row of heat exchange parts 28 to the second row of heat exchange parts 29, and it is possible to easily increase one refrigerant passage to four refrigerant passages at the liquid side refrigerant inlet and outlet 25 before flowing out to the gas collection pipe 24.

[0101] Furthermore, even while the refrigerant is being transferred from the refrigerant passage of the lower heat exchanger 12B to the refrigerant passage of the upper heat exchanger 12U using the passage connection pipe 26, the refrigerant can be branched using the three-pronged joint 23. Therefore, various refrigerant passages can be configured using only the three-pronged joint 23. This will be described in detail in the second and third embodiments.

[0102] While the three-pronged joint 23 requires structural changes at the ends of the three connected U-shaped heat transfer tubes 22, it can be easily standardized by designing the inlet on the refrigerant path side. In other words, the refrigerant path can be formed solely by a three-pronged joint 23 of the same shape. This eliminates the need to prepare three-pronged joints of different shapes, reducing component costs.

[0103] exist Figure 9In the refrigerant path of the illustrated embodiment, the gas header 24 is connected to all of the U-shaped heat transfer tubes 22 in two-thirds of the stages of the third row of heat exchange sections 30 of the upper heat exchanger 12U. Meanwhile, the liquid-side refrigerant inlet and outlet 25 of the liquid refrigerant distributor is connected to all of the U-shaped heat transfer tubes 22 in one-third of the stages of the first row of heat exchange sections 28 of the lower heat exchanger 12B.

[0104] Therefore, it will Figure 9 The number of refrigerant passages connected to the gas header 24 is set to eight refrigerant passages, which is more than Figure 6 The conventional heat exchanger shown has six refrigerant passages (the maximum number of refrigerant passages), which is a large number. Therefore, it is possible to effectively reduce the pressure loss when the heat exchanger is used as an evaporator.

[0105] exist Figure 6 In the existing refrigerant paths, the maximum number of refrigerant paths flowing to the gas header is only increased to the total number of stages / 2, but in this embodiment, the heat exchanger is divided into an upper side heat exchanger and a lower side heat exchanger, and on this basis, the number of refrigerant paths can be increased to the same number as the number of stages of the upper side heat exchanger.

[0106] And, in Figure 6 In the structure of the existing refrigerant path shown, for example, when the heat exchanger is used as an evaporator, if the refrigerant entering the first column heat exchange section 28 is evenly distributed to the U-shaped heat pipes of the second column heat exchange section 29 and the U-shaped heat pipes of the third column heat exchange section 30, the heat exchange amount of the third column heat exchange section 30 is smaller than the heat exchange amount of the second column heat exchange section 29, so it is considered that the refrigerant flowing into the third column heat exchange section 30 will not completely evaporate.

[0107] In contrast, in this embodiment, the U-shaped heat transfer pipes 22 spanning the two downwind rows of heat exchange units are arranged in the step direction. Consequently, there is no significant difference in the heat transfer capacity of the two U-shaped heat transfer pipes 22. In other words, even if the refrigerant entering the first row of heat exchange units 28 flows evenly through the two downwind rows of U-shaped heat transfer pipes 22, there is no performance degradation.

[0108] In addition, in the refrigerant path of this embodiment, the refrigerant passes through both the upper side heat exchanger 12U and the lower side heat exchanger 12B, so that the refrigerant can be obtained. Figure 7 That is, there is no need to consider the distribution adjustment of the refrigerant amount caused by the wind speed distribution, the design of the pressure loss body for adjustment, and the performance degradation caused by insufficient adjustment.

[0109] Furthermore, in this embodiment, when the heat exchanger is used as a condenser during cooling operation, the refrigerant gas flowing in from the gas header 24 passes from the leeward side to the windward side through the refrigerant passage provided in the upper heat exchanger 12U (which constitutes the upper two-thirds region of the heat exchanger 12), and then passes from the leeward side to the windward side through the subcooling region provided in the lower heat exchanger 12B (which constitutes the lower one-third region of the heat exchanger 12). Since the liquid-side refrigerant inlet and outlet 25 of the refrigerant passage provided in the region of the lower heat exchanger 12B is connected to the liquid refrigerant distributor, the head difference at the liquid-side inlet and outlet 25 can be reduced.

[0110] In addition, when the refrigerant flows from the refrigerant passage provided in the upper side heat exchanger 12U to the refrigerant passage provided in the lower side heat exchanger 12B, the refrigerant passages are concentrated and the number of refrigerant passages is reduced, thereby increasing the refrigerant flow rate on the liquid side and improving the cooling performance of the liquid refrigerant.

[0111] In air conditioning systems, increasing the degree of subcooling of the refrigerant at the condenser outlet during cooling operation improves performance. Therefore, providing a subcooling region in the lower heat exchanger 12B not only eliminates head differences but also improves heat exchanger performance.

[0112] Figure 9 In the embodiment, a 12-stage heat exchanger is used to illustrate this embodiment, but in reality, the stage spacing is set to 20 mm, and a 60-stage heat exchanger is used. In this case, the height of the heat exchanger is about 1.2 m. Since it is the same ratio, the upper side heat exchanger 12U has 40 stages, and the number of connection passages to the gas header 24 is also 40. Similarly, the lower side heat exchanger 12B has 20 stages, and the number of liquid side refrigerant inlets and outlets 25 is ten. In addition, in the heat exchanger 12 used in this embodiment, the upper side heat exchanger 12U and the lower side heat exchanger 12B are arranged in the height direction relative to the setting surface of the bottom setting plate 18 on which the outdoor heat exchanger 12 is provided, and the height length of the upper side heat exchanger 12U and the lower side heat exchanger 12B combined is preferably more than 1 m.

[0113] When used as an evaporator during heating operation, the refrigerant, divided into ten paths by the expansion valve and the liquid refrigerant distributor, flows into the ten liquid-side refrigerant inlets and outlets 25. After passing through the first row of heat exchangers 28 of the lower heat exchanger 12B among the ten refrigerant paths, the refrigerant reaches the second row of heat exchangers 29. Because each refrigerant path is split into two by the three-pronged joint 23, the refrigerant passes through the two rows of heat exchangers 29 and 30 on the leeward side of the lower heat exchanger 12B among the 20 refrigerant paths.

[0114] After passing through the 20 channel connecting tubes 26, the refrigerant passes through the first row of heat exchangers 28 in the upper heat exchanger 12U in the 20 refrigerant channels. Furthermore, when reaching the second row of heat exchangers 29 from the first row of heat exchangers 28 in the upper heat exchanger 12U, the refrigerant channel further branches into two at the three-pronged joint 23, resulting in the refrigerant passing through the two downwind rows of heat exchangers 29 and 30 in the upper heat exchanger in the 40 refrigerant channels. Since the 40 refrigerant channels are then connected to the gas header 24, the refrigerant merges there and flows to the four-way valve.

[0115] According to the present embodiment described above, in a heat exchanger using a round U-shaped heat transfer tube, the number of refrigerant passages on the gas side can be ensured, and the refrigerant passages can be configured as a two-stage structure consisting of an upper heat exchanger and a lower heat exchanger.

[0116] This reduces the impact of wind speed distribution on each refrigerant path, thereby reducing the cost of distribution adjustments. Furthermore, even with a top-flow type, high-profile heat exchanger, the concentration of liquid-side refrigerant inlets and outlets on the lower heat exchanger reduces head differences when used as a condenser, improving cooling performance.

[0117] Furthermore, since the number of refrigerant channels in the lower heat exchanger can be reduced, subcooling is easily achieved when used as a condenser, thereby improving cooling capacity. Furthermore, the use of a three-pronged joint facilitates the splitting of the refrigerant into two branches when flowing from the first to the second row of heat exchangers. Furthermore, by using three-pronged joints only in the first and second rows of heat exchangers in the upper and lower heat exchangers, the number of refrigerant channels connected to the gas manifold can be quadrupled compared to the number of refrigerant channels at the liquid refrigerant inlet and outlet.

[0118] Furthermore, since a three-pronged joint can be manufactured at a low cost compared to a distributor or a distribution joint that branches into three or more branches, the refrigerant passage can be constituted by only the three-pronged joint, which leads to cost reduction.

[0119] Furthermore, in this embodiment, the lowest refrigerant path with a slower air velocity is connected to the highest refrigerant path with a faster air velocity. This ensures that the air volume received by a single refrigerant path is relatively uniform at the lower and upper portions of the heat exchanger. This allows for a more even distribution of refrigerant to each refrigerant path, particularly when used as an evaporator, improving heating performance.

[0120] Specifically, in existing refrigerant circuits, the refrigerant distribution rate must be adjusted based on the wind speed distribution. This involves installing a narrow-diameter tube between the liquid refrigerant distributor and the liquid-side refrigerant circuit, adjusting the distribution rate by adjusting its length, for example. Consequently, it is difficult to consistently achieve the optimal distribution ratio for each refrigerant circulation volume. However, if this distribution ratio could be adjusted roughly uniformly, adjustments to each refrigerant circuit using narrow-diameter tubes would be unnecessary, allowing for near-optimal performance even with changes in the refrigerant circulation volume.

[0121] According to this embodiment, in a heat exchanger using round tubes, while taking into account the influence of the water head caused by the wind speed distribution and the height of the heat exchanger, it is possible to achieve high heating capacity and improved cooling performance at low cost.

[0122] Example 2

[0123] Next, a second embodiment of the present invention will be described. Figure 11 The refrigerant paths of this embodiment are shown. In the first embodiment, a three-pronged joint 23 was used in the lower heat exchanger 12B to increase the number of refrigerant paths. However, in this embodiment, the following structure is proposed: in the lower heat exchanger 12B, the number of paths is not increased by using the three-pronged joint 23. Instead, the three-pronged joint 23 is used to branch the refrigerant paths into two branches just before the first row of heat exchange sections 28 in the upper heat exchanger 12U, thereby increasing the number of refrigerant paths.

[0124] Figure 11 In heating operation, when the heat exchanger is used as an evaporator, the refrigerant entering the U-shaped heat transfer tubes of the first row of heat exchange sections 28 of the lower heat exchanger 12B flows into the two cross-row U-shaped heat transfer tubes of the second row of heat exchange sections 29, located downwind of the U-shaped heat transfer tubes of the first row of heat exchange sections 28. Thereafter, the refrigerant from the third row of heat exchange sections 30 flows through the cross-row U-shaped heat transfer tubes and into the upper heat exchanger 12U through the passage connection tube 26.

[0125] The refrigerant passage is constructed so that before it flows into the first row of heat exchange parts 28 of the upper side heat exchanger 12U, it is divided into two branches by the three-pronged joint 23 and the number of refrigerant passages increases. After passing through the first row of heat exchange parts 28, before it flows into the second row of heat exchange parts 29, it is again divided into two branches by the three-pronged joint 23 and the number of refrigerant passages increases.

[0126] On the other hand, when the heat exchanger is used as a condenser during cooling operation, the refrigerant flow is opposite to the refrigerant flow described above for the evaporator. Specifically, the gas refrigerant flowing from the gas header into the upper heat exchanger 12U in eight refrigerant paths passes through the two rows of heat exchangers 29 and 30 on the leeward side of the upper heat exchanger 12U, and then passes through the first row of heat exchangers 28 in the upper heat exchanger 12U, where the three-pronged joint 23 forms four refrigerant paths.

[0127] Furthermore, the refrigerant that has passed through the first row of heat exchangers 28 of the upper heat exchanger 12U passes through the three-way joint 23 again, forming two refrigerant paths, and flows into the lower heat exchanger 12B through two path connecting pipes 26. In the lower heat exchanger, the refrigerant flows through the two refrigerant paths and out of the liquid refrigerant inlet and outlet 25 to the liquid refrigerant distributor.

[0128] By ensuring that the number of refrigerant passages in the lower heat exchanger 12B is the same as the number of refrigerant inlets and outlets on the liquid side, the region with a high refrigerant flow rate is expanded, making it easier to achieve subcooling. Therefore, by not increasing the number of refrigerant passages in the lower heat exchanger, it is possible to improve cooling capacity.

[0129] Example 3

[0130] Next, a third embodiment of the present invention will be described. Figure 12 The refrigerant paths of this embodiment are shown. In the first embodiment, the number of refrigerant paths was increased using a three-pronged joint 23 in the lower heat exchanger 12B. However, in this embodiment, the following structure is proposed: in the lower heat exchanger 12B, after the number of refrigerant paths is increased using the three-pronged joint 23, the number of refrigerant paths is restored. Near the first row of heat exchange sections 28 in the upper heat exchanger 12U, the three-pronged joint 23 splits the refrigerant paths into two branches, thereby increasing the number of refrigerant paths.

[0131] Figure 12 When the heat exchanger is used as an evaporator in heating operation, first, the two-phase flow of the refrigerant after passing through the expansion valve is distributed through the liquid refrigerant distributor, and then only a small amount flows into the two liquid side refrigerant inlets and outlets 25 through the narrow-diameter tube for adjusting the distribution amount.

[0132] Refrigerant entering through the two liquid-side refrigerant inlets and outlets 25 rises through the U-shaped heat transfer pipes of the first row of heat exchangers 28, is distributed, and flows into two cross-row U-shaped heat transfer pipes arranged across the second row of heat exchangers 29 and the third row of heat exchangers 30 located immediately downwind. When branching from the first row of heat exchangers 28 to the second row of heat exchangers 29, as described above, the branching is performed using the three-pronged joint 23.

[0133] The refrigerant passing through the third row of heat exchangers 30 then flows again into a single refrigerant path joined by the three-way joint 23, and reaches the upper heat exchanger 12U through the path connecting pipe 26. The refrigerant path then branches into two again at the three-way joint 23 before flowing into the first row of heat exchangers 28 of the upper heat exchanger. The refrigerant flows through these two branched refrigerant paths into the first row of heat exchangers 28 of the upper heat exchanger 12U.

[0134] Furthermore, between the first row of heat exchangers 28 and the second row of heat exchangers 29 in the upper heat exchanger 12U, the refrigerant path is split into two branches by the three-pronged joint 23, thereby increasing the number of refrigerant paths. The vaporized refrigerant then flows into the gas header 24 from the eight (all stages) refrigerant paths of the third row of heat exchangers 30 in the upper heat exchanger 12U.

[0135] By adopting such a configuration, the number of passage connection pipes in the middle can be reduced to two, which is half the number of the refrigerant passages shown in the first embodiment, thereby suppressing an increase in manufacturing cost.

[0136] Furthermore, in this embodiment, the lower, slower refrigerant path is connected to the upper, faster refrigerant path. This ensures that the airflow received by a single refrigerant path is relatively uniform at both the lower and upper portions of the heat exchanger. This allows for a more even distribution of refrigerant to each refrigerant path, particularly when used as an evaporator, improving heating performance.

[0137] Specifically, in existing refrigerant circuits, the refrigerant distribution rate must be adjusted based on the wind speed distribution. This involves installing a narrow-diameter tube between the liquid refrigerant distributor and the liquid-side refrigerant circuit, adjusting the distribution rate by adjusting its length, for example. Consequently, it is difficult to consistently achieve the optimal distribution ratio for each refrigerant circulation volume. However, if this distribution ratio could be adjusted roughly uniformly, adjustments to each refrigerant circuit using narrow-diameter tubes would be unnecessary, allowing for near-optimal performance even with changes in the refrigerant circulation volume.

[0138] Furthermore, in this embodiment, the liquid-side refrigerant outlet of the lower heat exchanger is located below the U-shaped heat transfer tubes of the first row of heat exchange units in the direction of gravity. This is effective when the heat exchanger is used as a condenser during cooling operation, as it improves the drainage of liquid refrigerant from the heat transfer tubes due to at least gravity, thereby improving cooling performance.

[0139] In the first to third embodiments described above, the number of refrigerant passages in the U-shaped heat transfer tube connected to the liquid refrigerant distributor of the lower heat exchanger 12B (e.g., two refrigerant passages) is preferably four times the number of refrigerant passages in the U-shaped heat transfer tube connected to the gas header 24 of the upper heat exchanger 12U (e.g., eight refrigerant passages). This improves both heating and cooling performance, as described above.

[0140] Furthermore, the present invention is not limited to the above-described embodiments and includes various variations. For example, the above-described embodiments are described in detail to facilitate understanding of the present invention and are not necessarily limited to all of the described structures. Furthermore, a portion of the structure of one embodiment can be replaced with a structure of another embodiment, and a structure of another embodiment can be added to a structure of one embodiment. Furthermore, a portion of the structure of each embodiment can be added, deleted, or replaced with another structure.

[0141] Explanation of symbols

[0142] 9—Refrigerant piping, 10—Compressor, 11—Refrigerant tank, 12—Outdoor heat exchanger, 12B—Lower side heat exchanger, 12U—Upper side heat exchanger, 13—Outdoor air supply fan, 14—Energy accumulator, 15—Front panel, 16—Bell mouth, 17—Control panel, 18—Bottom setting plate, 19—Four-way valve, 20—Outdoor expansion valve, 21—Heat exchange fin, 22—U-shaped heat pipe, 22B—Bend part, 22E— End, 23—three-pronged joint, 24—gas header, 25—liquid side refrigerant inlet and outlet, 26—passage connecting pipe, 28—first row heat exchange part, 29—second row heat exchange part, 30—third row heat exchange part, 100—outdoor unit, 101—gas refrigerant piping, 102—liquid refrigerant piping, 103—indoor unit, 104—indoor heat exchanger, 105—indoor fan, 106—indoor expansion valve, 300—living room.

Claims

1. An outdoor unit of an air conditioner, comprising at least a compressor, an air supply fan, and a heat exchanger, wherein: The air supply fan is mounted on the upper part of the heat exchanger. The heat exchanger is composed of an upper heat exchanger and a lower heat exchanger, each of which is composed of a U-shaped heat transfer pipe formed by a round pipe bent into a U shape, a heat exchange fin, a liquid refrigerant distributor, a gas header, and a passage connection pipe connecting the ends of the U-shaped heat transfer pipe. The heat exchanger is composed of three rows of heat exchange parts arranged along the direction of air flow. The first row of heat exchangers on the upwind side of the heat exchangers is configured such that the U-shaped heat conducting pipes are arranged overlappingly in the level direction, and the two rows on the downwind side are configured such that the U-shaped heat conducting pipes span the second row of heat exchangers and the third row of heat exchangers. The ends of the U-shaped heat transfer tubes of the third row of heat exchange sections of the upper heat exchanger are connected to the gas header, the number of refrigerant passages connected to the gas header is greater than the total number of stages of the heat exchanger / 2, and the number of stages of the upper heat exchanger is the same as the number of refrigerant passages connected to the gas header. The end of the U-shaped heat pipe of the first row of heat exchange parts of the lower side heat exchanger is connected to the liquid refrigerant distributor, and the end of the U-shaped heat pipe of the third row of heat exchange parts of the lower side heat exchanger is connected to the end of the U-shaped heat pipe of the first row of heat exchange parts of the upper side heat exchanger via the passage connecting pipe.

2. The outdoor unit of the air conditioner according to claim 1, wherein: The upper heat exchanger and the lower heat exchanger are arranged side by side in a height direction relative to a ground plane on which the heat exchanger is installed, and a total height length of the upper heat exchanger and the lower heat exchanger is 1 m or more.

3. The outdoor unit of the air conditioner according to claim 1, wherein: The number of refrigerant passages formed by the U-shaped heat transfer tubes connected to the gas header is set to four times the number of refrigerant passages formed by the U-shaped heat transfer tubes connected to the liquid refrigerant distributor.

4. The outdoor unit of the air conditioner according to claim 3, wherein: The refrigerant passage of the lower heat exchanger connected to the liquid refrigerant distributor is divided into two branches via a three-pronged joint after passing through the first row of heat exchange parts and passes through the second row of heat exchange parts and the third row of heat exchange parts of the lower heat exchanger. The refrigerant path after being divided into two branches passes through the above-mentioned first row of heat exchange parts of the above-mentioned upper side heat exchanger, and is further divided into two branches through the above-mentioned three-way joint and passes through the above-mentioned second row of heat exchange parts and the above-mentioned third row of heat exchange parts of the above-mentioned upper side heat exchanger, and is connected to the above-mentioned gas collecting pipe.

5. The outdoor unit of the air conditioner according to claim 3, wherein: The refrigerant passage of the lower heat exchanger connected to the liquid refrigerant distributor passes through the first row of heat exchangers and then passes through the second row of heat exchangers and the third row of heat exchangers of the lower heat exchanger. The refrigerant path after passing through the third row of heat exchangers of the lower heat exchanger is divided into two branches via a three-pronged joint before passing through the first row of heat exchangers of the upper heat exchanger. The refrigerant path after being divided into two branches passes through the above-mentioned first row of heat exchange parts of the above-mentioned upper side heat exchanger, and then further divides into two branches through the above-mentioned three-way joint and passes through the above-mentioned second row of heat exchange parts and the above-mentioned third row of heat exchange parts of the above-mentioned upper side heat exchanger, and is connected to the above-mentioned gas header.

6. The outdoor unit of the air conditioner according to claim 3, wherein: The refrigerant passage of the lower side heat exchanger connected to the liquid refrigerant distributor is divided into two branches via a three-way junction after passing through the first row of heat exchangers and passes through the second row of heat exchangers and the third row of heat exchangers of the lower side heat exchanger, and then merges again via the three-way junction after passing through the third row of heat exchangers. The refrigerant path after passing through the third row of heat exchangers of the lower heat exchanger is divided into two branches via the three-way joint before passing through the first row of heat exchangers of the upper heat exchanger. The refrigerant path after being divided into two branches passes through the above-mentioned first row of heat exchange parts of the above-mentioned upper side heat exchanger, and then further divides into two branches through the above-mentioned three-way joint and passes through the above-mentioned second row of heat exchange parts and the above-mentioned third row of heat exchange parts of the above-mentioned upper side heat exchanger, and is connected to the above-mentioned gas header.

7. The outdoor unit of the air conditioner according to any one of claims 4 to 6, characterized in that: The connection portion of the lower heat exchanger to the liquid refrigerant distributor is an end portion on the lower side in the gravity direction of the U-shaped heat transfer tubes arranged in the stage direction of the first row of heat exchangers.

8. The outdoor unit of the air conditioner according to any one of claims 4 to 6, characterized in that: At least the three-pronged joint, the gas header, the end of the U-shaped heat transfer pipe, and the passage connection pipe are collectively arranged on one side of a plane parallel to the flow of air passing through the heat exchanger.

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