Air conditioner heat exchanger

Abstract

This heat exchanger for air conditioning comprises: a plurality of fins disposed at intervals therebetween in a first direction; a heat transfer pipe which is provided passing through the plurality of fins and has a hairpin section that folds back at an end section in the first direction; and a holder that has a tube section in which the hairpin section is accommodated, wherein the heat transfer pipe has a first straight pipe section and a second straight pipe section that are side by side in the vertical direction, the first straight pipe section is positioned above the second straight pipe section, the hairpin section is provided between the first straight pipe section and the second straight pipe section and connects the first straight pipe section and the second straight pipe section, the outer circumferential surface of the hairpin section has a first hydrophilic section that is formed with a hydrophilic coating film in a portion positioned higher than the axis of the second straight pipe section in the vertical direction, and the inner circumferential surface in a lower surface section of the tube section has a second hydrophilic section that is formed with a hydrophilic coating film.

Description

Technical Field

[0001] The present disclosure relates to an air conditioner heat exchanger including a holder for accommodating a hairpin portion of a heat transfer tube.

Background Art

[0002] As an air conditioner heat exchanger, there is known an air conditioner heat exchanger including a plurality of fins, a heat transfer tube having one end folded back at a hairpin portion and penetrating through the plurality of fins, and a holder for accommodating the hairpin portion of the heat transfer tube. For example, Patent Document 1 describes an air conditioner heat exchanger including a holder having functions such as ensuring strength, optimizing an air passage, and preventing corrosion at the hairpin portion.

[0003] Here, in the air conditioner heat exchanger as described in Patent Document 1, since the condensed water generated on the surface of the heat exchanger during the cooling operation continuously stays in the gap between the hairpin portion and the inner peripheral surface of the holder due to surface tension, there is a concern about the occurrence of corrosion at the hairpin portion. Therefore, in Patent Document 1, it is proposed to sufficiently open the gap between the hairpin portion and the inner peripheral surface of the holder so that the condensed water flows down to prevent the condensed water from staying and avoid the occurrence of corrosion.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, the condensed water adhering to the hairpin portion tends to gather vertically on the hairpin portion due to gravity. Therefore, even if there is a sufficient gap between the hairpin portion and the inner peripheral surface of the holder, the condensed water may gather and continue to stay due to surface tension in a state where the gap is blocked. Further, the condensed water that has fallen from the hairpin portion is received by the bottom surface of the holder. For this reason, even when the condensed water falls from the hairpin portion, the condensed water may continue to stay in a state where the gap between the heat transfer tube and the bottom surface of the holder is blocked. Therefore, there is a risk of corrosion occurring in the hairpin portion due to the condensed water remaining in the gap between the heat transfer tube and the inner peripheral surface of the holder for a long time.

[0006] The present disclosure has been made to solve the above problems, and provides an air conditioner heat exchanger that suppresses the occurrence of corrosion in the hairpin portion of a heat transfer tube.

Means for Solving the Problems

[0007] The air conditioner heat exchanger according to the present disclosure includes a plurality of fins arranged at intervals in a first direction, a heat transfer tube provided through the plurality of fins and having a hairpin portion that folds back at an end in the first direction, and a holder having a cylindrical portion in which the hairpin portion is housed. The heat transfer tube has a first straight tube portion and a second straight tube portion arranged vertically. The first straight tube portion is located above the second straight tube portion. The hairpin portion is provided between the first straight tube portion and the second straight tube portion and connects the first straight tube portion and the second straight tube portion. The outer peripheral surface of the hairpin portion has a first hydrophilic portion on which a hydrophilic film is formed in a portion located above the axis of the second straight tube portion in the vertical direction. The On the inner peripheral surface, in a portion located below the axis of the second straight pipe portion, The cylindrical portion has a second hydrophilic portion on which a hydrophilic film is formed. A hydrophilic film is not formed on the portion located above the axis of the second straight pipe portion, The first hydrophilic portion is not provided in the region where the second hydrophilic portion is projected onto the outer peripheral surface of the hairpin portion.

Effects of the Invention

[0008] According to the present disclosure, the hairpin portion of the heat transfer tube has a first hydrophilic portion with a hydrophilic film formed on the outer peripheral surface located above the axis of the second straight tube portion. Further, the cylindrical portion of the holder in which the hairpin portion is housed has a second hydrophilic portion with a hydrophilic film formed on the inner peripheral surface of the bottom surface portion. Therefore, above the axis of the second straight tube portion, dew condensation water is likely to move due to the first hydrophilic portion, and it is suppressed that the dew condensation water stays so as to block the gap between the outer peripheral surface of the hairpin portion and the inner peripheral surface of the cylindrical portion of the holder. Also, at the bottom surface portion of the holder, dew condensation water is likely to move due to the second hydrophilic portion, and it is suppressed that the dew condensation water stays so as to block the gap between the inner peripheral surface of the holder and the outer peripheral surface of the hairpin portion. Therefore, it is possible to suppress the long-term adhesion of dew condensation water to the hairpin portion of the heat transfer tube, and thus it is possible to suppress the occurrence of corrosion at the hairpin portion.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Modes for Carrying Out the Invention

[0010] Hereinafter, embodiments of the air conditioner heat exchanger according to the present disclosure will be described with reference to the accompanying drawings. Note that the form of the drawings is an example and does not limit the present disclosure. Also, in each figure, those with the same reference numerals are the same or corresponding ones, which is common throughout the entire specification. In the following description, for those that are repeated, they will be simplified or omitted as appropriate. Note that the present disclosure is not limited by the embodiments described below, and can include any combination of the configurations disclosed by the following embodiments. Also, the positions, shapes, and sizes of the respective components in the accompanying drawings may be different from the actual ones. Furthermore, in the cross-sectional views of the accompanying drawings, hatching is appropriately omitted for visibility.

[0011] Also, in the following description, terms representing directions are appropriately used for easy understanding, but this is for the purpose of explanation and these terms do not limit the present disclosure. Examples of terms representing directions include, for example, "up", "down", "right", "left", "front", or "rear".

[0012] Embodiment 1. FIG. 1 is a circuit diagram showing an air conditioner 1 according to Embodiment 1. The air conditioner 1 is a device for adjusting indoor air, and includes an outdoor unit 2 and an indoor unit 3. The outdoor unit 2 is provided with, for example, a compressor 6, a flow path switching device 7, an outdoor heat exchanger 8, an outdoor blower 9, and an expansion section 10. The indoor unit 3 is provided with, for example, an air conditioner heat exchanger 11 and a blower 12.

[0013] The compressor 6, the flow path switching device 7, the outdoor heat exchanger 8, the expansion section 10, and the air conditioning heat exchanger 11 are connected by the refrigerant pipe 5 to form the refrigerant circuit 4. The compressor 6 sucks in the refrigerant in a low-temperature and low-pressure state, compresses the sucked refrigerant, and discharges it as a high-temperature and high-pressure refrigerant. The flow path switching device 7 switches the direction in which the refrigerant flows in the refrigerant circuit 4 and is, for example, a four-way valve. The outdoor heat exchanger 8 exchanges heat between, for example, outdoor air and the refrigerant. The outdoor heat exchanger 8 acts as a condenser during the cooling operation and the dehumidifying operation, and acts as an evaporator during the heating operation. The outdoor blower 9 is a device that sends outdoor air to the outdoor heat exchanger 8.

[0014] The expansion section 10 is a pressure reducing valve or an expansion valve that reduces the pressure of the refrigerant and causes it to expand. The expansion section 10 is, for example, an electronic expansion valve whose opening degree is adjusted. The air conditioning heat exchanger 11 exchanges heat between, for example, indoor air and the refrigerant. The air conditioning heat exchanger 11 acts as an evaporator during the cooling operation and the dehumidifying operation, and acts as a condenser during the heating operation. The blower 12 is a device that sends indoor air to the air conditioning heat exchanger 11.

[0015] (Cooling operation and dehumidifying operation) Next, the operation of the air conditioner 1 will be described. First, the cooling operation and the dehumidifying operation will be described. In the cooling operation and the dehumidifying operation, the refrigerant sucked into the compressor 6 is compressed by the compressor 6 and discharged in a high-temperature and high-pressure gaseous state. The refrigerant in the high-temperature and high-pressure gaseous state discharged from the compressor 6 passes through the flow path switching device 7 and flows into the outdoor heat exchanger 8 acting as a condenser. In the outdoor heat exchanger 8, it exchanges heat with the outdoor air sent by the outdoor blower 9 and condenses and liquefies. The condensed liquid-state refrigerant flows into the expansion section 10, where it expands and decompresses to become a low-temperature and low-pressure gas-liquid two-phase state refrigerant. Then, the gas-liquid two-phase state refrigerant flows into the air-conditioning heat exchanger 11 acting as an evaporator, where it exchanges heat with the indoor air sent by the blower 12 and evaporates and gasifies. At this time, by cooling the indoor air, cooling or dehumidification is performed indoors. The evaporated low-temperature and low-pressure gaseous refrigerant passes through the flow path switching device 7 and is sucked into the compressor 6.

[0016] (Heating operation) Next, the heating operation will be described. In the heating operation, the refrigerant sucked into the compressor 6 is compressed by the compressor 6 and discharged in a high-temperature and high-pressure gaseous state. The refrigerant in the high-temperature and high-pressure gaseous state discharged from the compressor 6 passes through the flow path switching device 7 and flows into the air-conditioning heat exchanger 11 acting as a condenser. In the air-conditioning heat exchanger 11, it exchanges heat with the indoor air sent by the blower 12 and condenses and liquefies. At this time, the indoor air is heated, and heating is performed indoors. The condensed liquid-state refrigerant flows into the expansion section 10, where it expands and decompresses to become a low-temperature and low-pressure gas-liquid two-phase state refrigerant. Then, the gas-liquid two-phase state refrigerant flows into the outdoor heat exchanger 8 acting as an evaporator, where it exchanges heat with the outdoor air sent by the outdoor blower 9 and evaporates and gasifies. The evaporated low-temperature and low-pressure gaseous refrigerant passes through the flow path switching device 7 and is sucked into the compressor 6.

[0017] (Air-conditioning heat exchanger 11) FIG. 2 is a perspective view showing the air conditioner heat exchanger 11 according to Embodiment 1. In the present disclosure, as shown in FIG. 2, the first direction X shall indicate the width direction of the air conditioner heat exchanger 11. The second direction Y shall indicate the vertical direction of the air conditioner heat exchanger 11. The third direction Z shall indicate the front-rear direction of the air conditioner heat exchanger 11. The air conditioner heat exchanger 11 includes a plurality of fins 20, a plurality of heat transfer tubes 30, and a holder 40.

[0018] (Fins 20) The plurality of fins 20 are arranged side by side at intervals in the first direction X, which is the width direction of the air conditioner heat exchanger 11. The indoor air sucked into the air conditioner heat exchanger 11 passes between the plurality of fins 20.

[0019] (Heat transfer tubes 30) The heat transfer tubes 30 are made of, for example, metal and are provided so as to penetrate through the plurality of fins 20. The heat transfer tubes 30 have hairpin portions 31 that are folded back at the ends in the first direction X. The hairpin portions 31 are bent at a predetermined curvature by 180 degrees. When the air conditioner 1 is in operation, the refrigerant flows through the inside of the heat transfer tubes 30. A part of the heat transfer tubes 30 is exposed from between the plurality of fins 20 arranged in the first direction X. Thereby, the indoor air passing between the plurality of fins 20 hits the heat transfer tubes 30, and heat exchange is performed between the refrigerant flowing through the inside of the heat transfer tubes 30 and the indoor air. The heat transfer tubes 30 have a cylindrical shape. At one end in the first direction X, a refrigerant pipe 5 is connected to a part of the heat transfer tubes 30. The refrigerant pipe 5 is covered with a pipe cover 13. The refrigerant pipe 5 is protected by the pipe cover 13 and insulated from the outside air.

[0020] (Holder 40 and hairpin portion 31) As shown in FIG. 2, the holder 40 is provided at one end in the first direction X in a unit in which the fins 20 and the heat transfer tubes 30 are combined. The end in the first direction X where the holder 40 is provided is the end opposite to the end to which the refrigerant pipe 5 is connected to the heat transfer tube 30. The holder 40 has a function of ensuring the strength of the air conditioner heat exchanger 11 and protecting the hairpin portion 31 of the heat transfer tube 30. The holder 40 is made of, for example, resin.

[0021] The holder 40 and the hairpin portion 31 of the heat transfer tube 30 will be described with reference to FIGS. 3 to 7. FIG. 3 is a front view of the holder 40 according to the first embodiment. FIG. 4 is a partial perspective view of the cylindrical portion 42 of the holder 40 and the heat transfer tube 30 according to the first embodiment. In FIG. 4, the outer shapes of the holder 40, the fins 20, and the heat transfer tubes 30 are shown in a simplified manner. FIG. 5 is a simplified front view showing the cylindrical portion 42 and the hairpin portion 31 of the holder 40 according to the first embodiment. FIG. 5 shows a part of the holder 40 extracted. FIG. 6 is a schematic view showing the hydrophilic portion 51 according to the first embodiment. FIG. 7 is a schematic longitudinal sectional view taken along line A-A of FIG. 3.

[0022] As shown in FIG. 3, the holder 40 has an opening 41. Further, as shown in FIG. 4, a cylindrical portion 42 of the holder 40 protrudes outward in the first direction X from the edge of the opening 41 of the holder 40. Here, the outside in the first direction X refers to the side opposite to the side where the fins 20 are located. The holder 40 has a cylindrical opening 43 facing the opening 41.

[0023] As shown in FIGS. 4 and 7, the heat transfer tube 30 has a first straight tube portion 33 and a second straight tube portion 34 arranged vertically. The first straight tube portion 33 is located above the second straight tube portion 34. The hairpin portion 31 is provided between the first straight tube portion 33 and the second straight tube portion 34 and connects the first straight tube portion 33 and the second straight tube portion 34. The top 32 of the hairpin portion 31 is located in the middle of the first straight tube portion 33 and the second straight tube portion 34 in the vertical direction. In the heat transfer tube 30, the portion housed in the cylindrical portion 42 of the holder 40 is called the hairpin portion 31. The hairpin portion 31 includes a bent portion and a straight tube portion.

[0024] As shown in FIG. 4, the hairpin portion 31 of the heat transfer tube 30 is inserted into the opening 41 of the holder 40 and housed in the cylindrical portion 42 of the holder 40. A part of the outer peripheral surface 31a of the hairpin portion 31 faces a part of the inner peripheral surface 42a of the cylindrical portion 42. The cylindrical portion 42 has a bottom surface portion 42b. The cylindrical portion opening 43 is provided in the cylindrical portion 42. A second hydrophilic portion 51b, which will be described later, is provided on the inner peripheral surface 42a of the bottom surface portion 42b of the cylindrical portion 42. As shown in FIGS. 4 and 5, the hairpin portion 31 extending in the vertical direction can be visually observed from the cylindrical portion opening 43.

[0025] The hairpin portion 31 of the heat transfer tube 30 has a top portion 32 at the end in the first direction X. The top portion 32 is the vertex of the bent portion of the hairpin portion 31. As shown in FIGS. 4 and 7, the hairpin portion 31 is housed in the cylindrical portion 42 of the holder 40 without protruding from the cylindrical portion 42. Therefore, when the air conditioner heat exchanger 11 is viewed in the front-rear direction, that is, the third direction Z, the hairpin portion 31 is covered by the cylindrical portion 42 and not visible. The hairpin portion 31 is less likely to be affected from the outside by being housed in the cylindrical portion 42. In other words, the cylindrical portion 42 of the holder 40 protects the hairpin portion 31. In FIGS. 4 to 7, one hairpin portion 31 is housed in one cylindrical portion 42. However, although not shown, a configuration in which a plurality of hairpin portions 31 are housed in one cylindrical portion 42 may also be used.

[0026] The cylindrical portion 42 of the holder 40 optimizes the air flow path of the air flowing through the air conditioner heat exchanger 11. The cylindrical portion 42 causes the air flowing into the air conditioner heat exchanger 11 to flow in the first direction X toward the central portion of the air conditioner heat exchanger 11 where the fins 20 are arranged, rather than flowing in the third direction Z at the side portion of the air conditioner heat exchanger 11 where the hairpin portion 31 is arranged. As shown in FIG. 5, there is a gap SP between the outer peripheral surface 31a of the hairpin portion 31 inserted into the cylindrical portion 42 and the inner peripheral surface 42a of the cylindrical portion 42. Therefore, air can flow through this gap SP toward the central portion of the air conditioner heat exchanger 11.

[0027] (Hydrophilic portion 51) Next, with reference to FIGS. 6 and 7, the hydrophilic portions 51 on the outer peripheral surface 31a of the hairpin portion 31 and the inner peripheral surface 42a of the cylindrical portion 42 will be described. As shown in FIGS. 6 and 7, the outer peripheral surface 31a of the hairpin portion 31 has a first hydrophilic portion 51a formed by applying a hydrophilic coating film. Further, the inner peripheral surface 42a of the cylindrical portion 42 has a second hydrophilic portion 51b formed by applying a hydrophilic coating film. In the following description, when there is no need to particularly distinguish between the first hydrophilic portion 51a and the second hydrophilic portion 51b, they are simply referred to as "hydrophilic portion 51" as appropriate. Also, when referring to the "hydrophilic portion 51", it includes both singular and plural forms. The hydrophilic coating film of the hydrophilic portion 51 is applied to the outer peripheral surface 31a of the hairpin portion 31 and the inner peripheral surface 42a of the cylindrical portion 42 by, for example, spray coating or brush coating.

[0028] As shown in FIGS. 6 and 7, not all of the outer peripheral surface 31a of the hairpin portion 31 has the first hydrophilic portion 51a, nor does all of the inner peripheral surface 42a of the cylindrical portion 42 have the second hydrophilic portion 51b. As shown in FIG. 7, when the axis AX of the second straight tube portion 34 of the heat transfer tube 30 is extended to the hairpin portion 31, in the vertical direction, the first hydrophilic portion 51a is provided above the axis AX on the outer peripheral surface 31a of the hairpin portion 31. In other words, in the vertical direction, the first hydrophilic portion 51a is not provided on the outer peripheral surface 31a of the hairpin portion 31 located below the axis AX. Also, as shown in FIG. 6, the second hydrophilic portion 51b is provided below the axis AX on the inner peripheral surface 42a of the cylindrical portion 42. In other words, in the vertical direction, the second hydrophilic portion 51b is not provided on the inner peripheral surface 42a of the cylindrical portion 42 located above the axis AX.

[0029] Furthermore, on the outer peripheral surface 31a of the hairpin portion 31 located above the axis AX, the first hydrophilic portion 51a may not be provided in a portion that does not face the inner peripheral surface 42a of the cylindrical portion 42. For example, as shown in FIG. 7, for the straight pipe portion of the hairpin portion 31 connected to the first straight pipe portion 33 of the heat transfer pipe 30, the first hydrophilic portion 51a may not be provided on the outer peripheral surface 31a of the bottom surface. Also, for the straight pipe portion of the hairpin portion 31 connected to the second straight pipe portion 34 of the heat transfer pipe 30, the first hydrophilic portion 51a may not be provided on the outer peripheral surface 31a of the upper surface. Furthermore, the first hydrophilic portion 51a may not be provided on the outer peripheral surface 31a of the bent portion between the bottom surface of the upper straight pipe portion and the upper surface of the lower straight pipe portion of the hairpin portion 31.

[0030] Hereinafter, for the sake of easy explanation, the gap between the outer peripheral surface 31a of the hairpin portion 31 located above the axis AX having the first hydrophilic portion 51a and the inner peripheral surface 42a of the cylindrical portion 42 is referred to as gap SP1. Also, the gap between the outer peripheral surface 31a of the hairpin portion 31 located below the axis AX having no first hydrophilic portion 51a and the inner peripheral surface 42a of the cylindrical portion 42 is referred to as gap SP2. Also, when there is no need to particularly distinguish between gap SP1 and gap SP2, it is simply referred to as "gap SP" as appropriate.

[0031] As shown in FIGS. 6 and 7, the second hydrophilic portion 51b may be provided on the inner peripheral surface 42a of the bottom surface portion 42b of the cylindrical portion 42. More preferably, the second hydrophilic portion 51b is provided in a portion facing a portion of the inner peripheral surface 42a of the cylindrical portion 42 that faces the outer peripheral surface 31a of the hairpin portion 31 and where the first hydrophilic portion 51a is not provided. Also, when the second hydrophilic portion 51b is projected onto the outer peripheral surface 31a of the hairpin portion 31, the portion of the first hydrophilic portion 51a located below the axis AX and the region where the second hydrophilic portion 51b is projected do not overlap. That is, when the second hydrophilic portion 51b is projected onto the outer peripheral surface 31a of the hairpin portion 31, the first hydrophilic portion 51a is not provided in the projected region.

[0032] The hydrophilic part 51 suppresses the condensed water 50 from staying in a state where it blocks the gap SP between the outer peripheral surface 31a of the hairpin part 31 and the inner peripheral surface 42a of the cylindrical part 42. First, the state where the condensed water 50 stays in the gap SP between the outer peripheral surface 31a of the hairpin part 31 and the inner peripheral surface 42a of the cylindrical part 42 will be described with reference to FIG. 8. FIG. 8 is a schematic diagram showing a state where the condensed water 50 stays between the outer peripheral surface 31a of the hairpin part 31 and the inner peripheral surface 42a of the cylindrical part 42 of the holder 40 in the first embodiment.

[0033] When the air conditioner 1 performs a cooling operation or a dehumidifying operation and the air-conditioning heat exchanger 11 acts as an evaporator, the heat transfer tube 30 is cooled by the refrigerant flowing inside the heat transfer tube 30. At this time, if the humidity around the heat transfer tube 30 is high, condensation may occur on the surface of the heat transfer tube 30. While the cooling operation or the dehumidifying operation continues, when the amount of the condensed water 50 gradually increases, the condensed water 50 adheres in a state of straddling the gap SP between the outer peripheral surface 31a of the hairpin part 31 and the inner peripheral surface 42a of the cylindrical part 42. That is, the condensed water 50 blocks the gap SP. In such a state, the condensed water 50 becomes difficult to move and stays in the gap SP for a long time.

[0034] In the present embodiment, since the hydrophilic portion 51 is provided at a part of the portion where the gap SP is in contact, the condensed water 50 preferentially moves to the hydrophilic portion 51. For this reason, it is difficult for the condensed water 50 to stay in one place in the gap SP1 between the outer peripheral surface 31a of the hairpin portion 31 having the first hydrophilic portion 51a and the inner peripheral surface 42a of the cylindrical portion 42. Further, due to gravity, the condensed water 50 flows along the outer peripheral surface 31a of the hairpin portion 31 in the vertical direction and converges. Since the heat transfer tube 30 has a cylindrical shape, the condensed water 50 easily converges on the outer peripheral surface 31a of the bottom surface of the straight tube portion of the hairpin portion 31. Therefore, it is difficult for the condensed water 50 to stay in the gap SP1 between the outer peripheral surface 31a of the hairpin portion 31 located above the axis AX and the inner peripheral surface 42a of the cylindrical portion 42. Further, in the first hydrophilic portion 51a, since the contact angle of the condensed water 50 is small, a large amount of condensed water 50 needs to converge in order for the condensed water 50 to block the gap SP. However, since it is difficult for the condensed water 50 to stay in the gap SP1 between the outer peripheral surface 31a of the hairpin portion 31 located above the axis AX and the inner peripheral surface 42a of the cylindrical portion 42, it is suppressed that the condensed water 50 blocks the gap SP.

[0035] In addition, the condensed water 50 that has fallen from the hairpin portion 31 is received by the inner peripheral surface 42a of the bottom surface portion 42b of the cylindrical portion 42. Since the second hydrophilic portion 51b is provided on the inner peripheral surface 42a of the bottom surface portion 42b of the cylindrical portion 42, the contact angle of the condensed water 50 is small. Although a large amount of condensed water 50 needs to converge in order for the condensed water 50 to block the gap SP2, it is difficult for a large amount of condensed water 50 to stay in one place in the second hydrophilic portion 51b. Further, the first hydrophilic portion 51a of the hairpin portion 31 is not provided on the surface facing the second hydrophilic portion 51b. Therefore, even if the condensed water 50 adheres in a state of straddling the gap SP2 between the inner peripheral surface 42a of the bottom surface portion 42b of the cylindrical portion 42 and the outer peripheral surface 31a of the hairpin portion 31, the condensed water 50 preferentially moves to the second hydrophilic portion 51b. Therefore, it is difficult for the condensed water 50 to stay in a state of blocking the gap SP2 between the inner peripheral surface 42a of the bottom surface portion 42b of the cylindrical portion 42 and the outer peripheral surface 31a of the hairpin portion 31.

[0036] As described above, in the present embodiment, the air-conditioning heat exchanger 11 includes a plurality of fins 20 arranged at intervals in the first direction X, a heat transfer tube 30 provided through the plurality of fins 20 and having a hairpin portion 31 that turns back at an end in the first direction X, and a holder 40 having a cylindrical portion 42 in which the hairpin portion 31 is housed. The heat transfer tube 30 has a first straight tube portion 33 and a second straight tube portion 34 arranged vertically. The first straight tube portion 33 is located above the second straight tube portion 34. The hairpin portion 31 is provided between the first straight tube portion 33 and the second straight tube portion 34 and connects the first straight tube portion 33 and the second straight tube portion 34. The outer peripheral surface 31a of the hairpin portion 31 has a first hydrophilic portion 51a on which a hydrophilic film is formed in a portion located above the axis AX of the second straight tube portion 34 in the vertical direction. The inner peripheral surface 42a of the bottom surface portion 42b of the cylindrical portion 42 has a second hydrophilic portion 51b on which a hydrophilic film is formed.

[0037] According to this configuration, in the vertical direction, the outer peripheral surface 31a of the hairpin portion 31 of the heat transfer tube 30 located above the axis AX has the first hydrophilic portion 51a. On the other hand, the inner peripheral surface 42a of the cylindrical portion 42 located above the axis AX does not have the second hydrophilic portion 51b. Therefore, in the gap SP1 between the outer peripheral surface 31a of the hairpin portion 31 and the inner peripheral surface 42a of the cylindrical portion 42, which is located above the axis AX, the condensed water 50 preferentially moves to the first hydrophilic portion 51a. Thus, above the axis AX, it is difficult for the condensed water 50 to stay in a state where the gap SP1 is blocked. Further, as the condensed water 50 flows vertically and converges on the outer peripheral surface 31a of the hairpin portion 31, the condensed water 50 easily falls from the outer peripheral surface 31a of the hairpin portion 31 due to gravity. Also, the condensed water 50 that has fallen from the hairpin portion 31 is received by the inner peripheral surface 42a of the bottom surface portion 42b of the cylindrical portion 42 and preferentially moves to the second hydrophilic portion 51b. Therefore, it is difficult for the condensed water 50 to stay in a state where the gap SP2 between the inner peripheral surface 42a of the bottom surface portion 42b of the cylindrical portion 42 and the outer peripheral surface 31a of the facing hairpin portion 31 is blocked. In this way, it is possible to suppress the long-term adhesion of the condensed water 50 to the outer peripheral surface 31a of the hairpin portion 31, and thus it is possible to suppress the occurrence of corrosion in the hairpin portion 31. Therefore, the corrosion of the air conditioner heat exchanger 11 can be reduced, and a more reliable air conditioner heat exchanger 11 can be provided. Also, by reducing the corrosion of the air conditioner heat exchanger 11, a long-life air conditioner heat exchanger 11 can be realized.

[0038] Also, in the air conditioner heat exchanger 11 according to the present embodiment, the first hydrophilic portion 51a is not provided in the region where the second hydrophilic portion 51b is projected on the outer peripheral surface 31a of the hairpin portion 31. According to this configuration, the second hydrophilic portion 51b is provided facing the portion of the outer peripheral surface 31a of the hairpin portion 31 that does not have the first hydrophilic portion 51a. Dew water 50 that has fallen from the outer peripheral surface 31a of the hairpin portion 31 located above the axis AX may adhere to the outer peripheral surface 31a of the hairpin portion 31 located below the axis AX. However, the outer peripheral surface 31a of the hairpin portion 31 located below the axis AX does not have the hydrophilic portion 51. Therefore, the dew water 50 that has fallen and the dew water 50 that was originally adhering gather, and a state where the dew water 50 adheres across the gap SP2 is likely to occur. However, since the inner peripheral surface 42a of the cylindrical portion 42 has the second hydrophilic portion 51b, the dew water 50 preferentially moves to the second hydrophilic portion 51b. Therefore, it is possible to suppress the dew water 50 from remaining in a state where the gap SP2 between the outer peripheral surface 31a of the hairpin portion 31 and the inner peripheral surface 42a of the cylindrical portion 42 is blocked below the axis AX. Therefore, it is possible to suppress the dew water 50 from adhering to the outer peripheral surface 31a of the hairpin portion 31 located below the axis AX for a long time, and thus it is possible to suppress the occurrence of corrosion in the hairpin portion 31.

[0039] Embodiment 2. The difference between the air conditioner heat exchanger 11 according to Embodiment 2 and the air conditioner heat exchanger 11 according to Embodiment 1 is that the outer peripheral surface 31a of the hairpin portion 31 has a water repellent portion 52. Hereinafter, the water repellent portion 52 in the present embodiment will be described centering on the differences from Embodiment 1. Since the configuration of the air conditioner heat exchanger 11 of the present embodiment is the same as that of Embodiment 1 except for the water repellent portion 52, the description other than the water repellent portion 52 will be omitted. Also, for the same components as in Embodiment 1, the same reference numerals will be given and the description thereof will be appropriately omitted.

[0040] Referring to FIGS. 9 and 10, the water-repellent part 52 in the present embodiment will be described. FIG. 9 is a schematic view showing the water-repellent part 52 according to Embodiment 2. FIG. 10 is a schematic longitudinal sectional view of the holder 40 and the heat transfer tube 30 in Embodiment 2. FIG. 10 shows a longitudinal section taken along line A-A in FIG. 3. Also, in FIG. 10, the water-repellent part 52 is filled in for visibility.

[0041] As shown in FIGS. 9 and 10, the outer peripheral surface 31a of the hairpin part 31 has a water-repellent part 52 on which a water-repellent film is formed. As shown in FIG. 10, the water-repellent part 52 is provided at a portion of the outer peripheral surface 31a of the hairpin part 31 that is located below the axis AX. More specifically, the water-repellent part 52 is provided at a portion of the outer peripheral surface 31a of the hairpin part 31 that is located below the axis AX and where the first hydrophilic part 51a is not provided. Since a water-repellent film is formed in the water-repellent part 52, the contact angle of the condensed water 50 becomes larger, and the condensed water 50 adheres to the water-repellent part 52 in a substantially spherical shape. Therefore, the condensed water 50 rolls on the water-repellent part 52 and easily gathers on the outer peripheral surface 31a of the bottom surface of the straight pipe part located below the hairpin part 31. For this reason, the condensed water 50 easily adheres in a state of straddling the gap SP2 between the outer peripheral surface 31a of the bottom surface of the straight pipe part of the hairpin part 31 and the inner peripheral surface 42a of the bottom surface part 42b of the cylindrical part 42. However, since the inner peripheral surface 42a of the bottom surface part 42b of the cylindrical part 42 has the second hydrophilic part 51b, the condensed water 50 preferentially moves to the second hydrophilic part 51b. Therefore, it is possible to suppress the condensed water 50 from remaining in a state of blocking the gap SP2 located below the axis AX between the outer peripheral surface 31a of the bottom surface of the straight pipe part of the hairpin part 31 and the inner peripheral surface 42a of the bottom surface part 42b of the cylindrical part 42. Therefore, the occurrence of corrosion in the hairpin part 31 can be suppressed, and as a result, a highly reliable air conditioner heat exchanger 11 can be provided.

[0042] Also, in the air conditioner heat exchanger 11 according to the present embodiment, the water-repellent portion 52 is provided at a position facing the second hydrophilic portion 51b. In the water-repellent portion 52, even when the amount of the condensed water 50 adhering thereto is small, since the condensed water 50 adheres in a substantially spherical shape, the condensed water 50 is likely to come into contact with the inner peripheral surface 42a of the cylindrical portion 42 facing the water-repellent portion 52. Since the inner peripheral surface 42a of the cylindrical portion 42 facing the water-repellent portion 52 has the second hydrophilic portion 51b, the condensed water 50 preferentially moves to the second hydrophilic portion 51b. Therefore, even when the amount of the condensed water 50 adhering to the water-repellent portion 52 is small, the condensed water 50 can preferentially move to the second hydrophilic portion 51b of the inner peripheral surface 42a of the cylindrical portion 42. For this reason, the adhesion of the condensed water 50 to the hairpin portion 31 for a long time is suppressed. Therefore, the occurrence of corrosion in the hairpin portion 31 can be suppressed, and as a result, a highly reliable air conditioner heat exchanger 11 can be provided.

Explanation of Signs

[0043] 1 Air conditioner, 2 Outdoor unit, 3 Indoor unit, 4 Refrigerant circuit, 5 Refrigerant pipe, 6 Compressor, 7 Flow path switching device, 8 Outdoor heat exchanger, 9 Outdoor blower, 10 Expansion portion, 11 Air conditioner heat exchanger, 12 Blower, 13 Pipe cover, 20 Fin, 30 Heat transfer pipe, 31 Hairpin portion, 31a Outer peripheral surface, 32 Top portion, 33 First straight pipe portion, 34 Second straight pipe portion, 40 Holder, 41 Opening portion, 42 Cylindrical portion, 42a Inner peripheral surface, 42b Bottom surface portion, 43 Cylindrical portion opening, 50 Condensed water, 51 Hydrophilic portion, 51a First hydrophilic portion, 51b Second hydrophilic portion, 52 Water-repellent portion, SP Gap, SP1 Gap, SP2 Gap, AX Axis, X First direction, Y Second direction, Z Third direction.

Claims

1. A plurality of fins arranged at intervals in a first direction; A heat transfer tube provided through the plurality of fins and having a hairpin portion that turns back at an end in the first direction; A holder having a cylindrical portion in which the hairpin portion is housed and comprising: The heat transfer tube has a first straight tube portion and a second straight tube portion arranged vertically; The first straight tube portion is located above the second straight tube portion; The hairpin portion is provided between the first straight tube portion and the second straight tube portion and connects the first straight tube portion and the second straight tube portion; An outer peripheral surface of the hairpin portion has a first hydrophilic portion on which a hydrophilic film is formed at a portion located above an axis of the second straight tube portion in the vertical direction; On an inner peripheral surface of the cylindrical portion, a second hydrophilic portion on which the hydrophilic film is formed is provided at a portion located below the axis of the second straight tube portion, and the hydrophilic film is not formed at a portion located above the axis of the second straight tube portion; The first hydrophilic portion is not provided in a region where the second hydrophilic portion is projected on the outer peripheral surface of the hairpin portion Air conditioner heat exchanger.

2. The outer peripheral surface of the hairpin portion has a water-repellent portion on which a water-repellent film is formed at a portion located below the axis of the second straight tube portion The air conditioner heat exchanger according to claim 1.

3. The water-repellent portion is provided at a position facing the second hydrophilic portion The air conditioner heat exchanger according to claim 2.

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