Air conditioner

Abstract

The utility model provides an air conditioner. Compared with the prior art, white rust generated in an indoor unit is restrained. The air conditioner is provided with an indoor unit and an outdoor unit, wherein the indoor unit is provided with an indoor heat exchanger for carrying out heat exchange between indoor air and a refrigerant; and an outdoor unit having an outdoor heat exchanger that exchanges heat between outdoor air and a refrigerant, characterized in that: a refrigeration cycle pipe formed from aluminum or an aluminum alloy is connected to one end side and the other end side of the indoor heat exchanger and the outdoor heat exchanger; an alternative anti-corrosion layer is formed on the outer surface of the refrigeration cycle pipe disposed inside the outdoor unit and connected to the outdoor heat exchanger, and an alternative anti-corrosion layer is not formed on the outer surface of the refrigeration cycle pipe disposed inside the indoor unit and connected to the indoor heat exchanger.

Description

TECHNICAL FIELD

[0001] The utility model relates to an air conditioner. BACKGROUND

[0002] In the past, an air conditioner having a heat exchanger in which a sacrificial corrosion-resistant layer is formed on the entire surface of a heat transfer tube made of aluminum or an aluminum alloy is known (for example, refer to Patent Document 1). According to such an air conditioner, corrosion of aluminum that is a base material of the heat transfer tube is prevented by the sacrificial corrosion-resistant layer.

[0003] PRIOR ART DOCUMENTS

[0004] PATENT DOCUMENTS

[0005] Patent Document 1: Japanese Patent Application Publication No. 2023-051137 SUMMARY

[0006] PROBLEMS TO BE SOLVED BY THE INVENTION

[0007] However, since the sacrificial corrosion-resistant layer is usually composed of a metal such as zinc having a lower electric potential than the metal that forms the base material, white rust is easily generated.

[0008] However, if white rust is generated in the indoor unit of the air conditioner, the white rust is scattered into the room along with the supply air. In addition, the white rust can clog the drain hole through which the condensed water is discharged from the indoor heat exchanger.

[0009] The utility model discloses a kind of air conditioners, which are characterized by being configured to prevent white rust from being generated in an indoor unit compared to conventional air conditioners.

[0010] SOLUTIONS TO THE PROBLEMS

[0011] The utility model discloses a kind of air conditioners, which are characterized by being configured to prevent white rust from being generated in an indoor unit compared to conventional air conditioners.

[0012] The utility model discloses a kind of air conditioners, which are characterized by being configured to prevent white rust from being generated in an indoor unit compared to conventional air conditioners.

[0013] The air conditioner according to the scheme 3 is characterized in that the heat transfer pipe in the indoor heat exchanger and the outdoor heat exchanger is formed of aluminum or aluminum alloy, and an alternative anticorrosion layer is formed on the outer surface of the return bending part arranged on one side in the return bending part of the heat transfer pipe of the outdoor heat exchanger, and the alternative anticorrosion layer is not formed on the outer surface of the return bending part arranged on one side in the heat transfer pipe of the indoor heat exchanger.

[0014] The air conditioner according to the scheme 4 is characterized in that the alternative anticorrosion layer is formed on the outer surface of the return bending part arranged on the other side and the straight pipe part of the heat transfer pipe in the indoor heat exchanger.

[0015] The air conditioner according to the scheme 5 is characterized in that a cladding layer composed of synthetic rubber or synthetic resin is formed on the surface of the alternative anticorrosion layer of the return bending part arranged on the other side.

[0016] The air conditioner according to the scheme 6 is characterized in that a drain pan for receiving condensed water is arranged below the indoor heat exchanger, and a drain pipe for draining the condensed water from the drain pan extends downward from the bottom of the drain pan.

[0017] The air conditioner according to the scheme 7 is characterized in that the wall thickness of the return bending part arranged on one side and not formed with the alternative anticorrosion layer of the indoor heat exchanger is thicker than the wall thickness of the straight pipe part obtained by removing the thickness of the alternative anticorrosion layer in the straight pipe part of the indoor heat exchanger.

[0018] The air conditioner according to the scheme 8 is characterized in that the return bending part arranged on one side and not formed with the alternative anticorrosion layer of the indoor heat exchanger is formed of an aluminum alloy with high corrosion resistance compared with the return bending part of the outdoor heat exchanger with the alternative anticorrosion layer.

[0019] Practical effects

[0020] According to the air conditioner, white rust generated in the indoor unit can be inhibited compared with the prior art. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 is a structural explanatory view of an air conditioner according to an embodiment of the present application.

[0022] Figure 2 is Figure 1 is a structural explanatory view of an outdoor heat exchanger in the air conditioner shown in Fig. 1.

[0023] Figure 3 is a sectional view of a heat transfer pipe constituting the outdoor heat exchanger shown in Fig. 2. Figure 2

[0024] Figure 4 is a structural explanatory view of an indoor heat exchanger in the air conditioner shown in Fig. 1. Figure 1

[0025] Figure 5A is a sectional view of a straight pipe portion in the U-shaped pipe shown in Fig. 4. Figure 4

[0026] Figure 5B is a sectional view of a return bent portion in the U-shaped pipe shown in Fig. 5. Figure 4

[0027] Figure 5C is a sectional view of a connecting pipe shown in Fig. 6. Figure 4

[0028] Figure 6 is a sectional view of a dissimilar metal joint portion shown in Fig. 7. Figure 1

[0029] Figure 7 is a structural explanatory view of a drain pan shown in Fig. 8. Figure 1

[0030] in the drawing:

[0031] 3 - outdoor heat exchanger; 4 - indoor heat exchanger; 10a - pipe line; 10b - pipe line; 11 - fin; 12 - heat transfer pipe; 13 - U-shaped pipe; 13a - straight pipe portion; 13b - return bent portion; 14 - connecting pipe; 16 - anticorrosive layer; 17 - drain pan; 17a - bottom portion; 19 - drain pipe; 20b - second liquid pipe (refrigeration cycle pipe); 21 - fin; 22 - heat transfer pipe; 23 - U-shaped pipe; 23a - straight pipe portion; 23b - return bent portion; 24 - connecting pipe; 27 - cladding layer; 30b - second gas pipe (refrigeration cycle pipe); 100 - air conditioner; 101 - outdoor unit; 102 - indoor unit; Tl - wall thickness; T2 - wall thickness. DETAILED DESCRIPTION

[0032] ​​​​​​​Hereinafter, a mode (embodiment) for implementing the air conditioner of the present application will be described in detail with appropriate reference to the accompanying drawings. First, the overall structure of the air conditioner will be described, and then the indoor heat exchanger and the outdoor heat exchanger will be described in further detail.

[0033] <Air conditioner>

[0034] Figure 1 is a structural diagram of the air conditioner 100 of the present embodiment.

[0035] Further, in Figure 1 , solid arrows indicate the flow of refrigerant in the heating cycle, and dashed arrows indicate the flow of refrigerant in the cooling cycle.

[0036] As Figure 1 indicated, the air conditioner 100 is provided with an outdoor unit 101 disposed outdoors and an indoor unit 102 disposed indoors.

[0037] The air conditioner 100 during cooling operation takes in liquid refrigerant (including gas-liquid two-phase refrigerant) flowing in the heat transfer pipe 22 (see Figure 4 ) of the indoor heat exchanger 4 in the indoor unit 102 from the outdoor unit 101 via the liquid pipe 20 having an expansion valve 6 at the middle of the extension. At this time, the indoor heat exchanger 4 functions as an evaporator, thereby cooling the surrounding air. Furthermore, the gas refrigerant gasified in the indoor heat exchanger 4 is sent out to the outdoor unit 101 via the gas pipe 30.

[0038] The gas refrigerant sent out to the outdoor unit 101 becomes liquid refrigerant (including gas-liquid two-phase refrigerant) via the compressor 7 of the outdoor unit 101, the outdoor heat exchanger 3 functioning as a condenser. This liquid refrigerant is again sent out to the indoor unit 102 via the liquid pipe 20.

[0039] In addition, the air conditioner 100 during heating operation switches the refrigerant flow path by the four-way valve 8 of the outdoor unit 101, and sends out the high-temperature and high-pressure gas refrigerant from the compressor 7 to the indoor unit 102 via the gas pipe 30. At this time, the indoor heat exchanger 4 functions as a condenser, thereby heating the surrounding air. Furthermore, the liquid refrigerant (including gas-liquid two-phase refrigerant) condensed in the heat transfer pipe 22 (see Figure 4 ) of the indoor heat exchanger 4 is sent out to the outdoor unit 101 via the liquid pipe 20. The liquid refrigerant sent out to the outdoor unit 101 is again sent out to the indoor unit 102 as high-temperature and high-pressure gas refrigerant via the outdoor heat exchanger 3 functioning as an evaporator of the outdoor unit 101, the compressor 7.

[0040] Further, the liquid pipe 20 is composed of a first liquid pipe 20a composed of copper and second liquid pipes 20b each disposed at both ends of the first liquid pipe 20a and composed of aluminum or an aluminum alloy. Further, the gas pipe 30 is composed of a first gas pipe 30a composed of copper and second gas pipes 30b each disposed at both ends of the first gas pipe 30a and composed of aluminum or an aluminum alloy.

[0041] <Outdoor heat exchanger and indoor heat exchanger>

[0042] As shown in Figure 1 , the outdoor heat exchanger 3 performs heat exchange between outdoor air drawn into the outdoor unit 101 by the outdoor fan 9 and refrigerant flowing in the heat transfer pipe 12 (refer to Figure 2 ) to be described later. The outdoor air after heat exchange is discharged to the outside of the outdoor unit 101.

[0043] Figure 2 is a structural explanatory view of the outdoor heat exchanger 3. Further, in order to facilitate drawing, Figure 2 , the middle of the length direction (the stacking direction of the fins 11 to be described later) of the outdoor heat exchanger 3 is omitted. In addition, Figure 2 is a partial view of the outdoor heat exchanger 3 on the connecting side of the second gas pipe 30b shown in Figure 1

[0044] As shown in Figure 2 , the outdoor heat exchanger 3 is provided with plate-like fins 11 and a heat transfer pipe 12.

[0045] The plate-like fins 11 are stacked with a plurality of fins 11 spaced apart in the plate thickness direction.

[0046] The fins 11 in the present embodiment are formed of aluminum or an aluminum alloy.

[0047] As shown in Figure 2 , the heat transfer pipe 12 forms a meandering pipe route 10a by straight pipe portions 13a penetrating a plurality of fins 11 in the stacking direction and return bent portions 13b disposed at both outer sides sandwiching the stacked fins 11.

[0048] Specifically, the heat transfer pipe 12 has a plurality of U-shaped pipes 13 composed of a pair of straight pipe portions 13a and one return bent portion 13b connecting them, and a plurality of connection pipes 14 forming only the return bent portions 13b of the pipe route 10a.

[0049] The U-shaped pipe 13 in the present embodiment is assumed to be a pipe in which a straight pipe is bent into a U-shaped shape.

[0050] ​In addition, at the other end of the straight tube 13a through which multiple fins 11 pass, an enlarged diameter section 13a2 is formed, which has an inner diameter larger than that of the general section 13a1 that occupies most of the straight tube 13a.

[0051] The connecting tube 14 is in the shape of an arc, bent with the same curvature as the return bend 13b of the U-tube 13. The end of such a connecting tube 14 is pressed into the inside of the enlarged diameter portion 13a2 of the U-tube 13 and connected to the enlarged diameter portion 13a2 by brazing.

[0052] And, as Figure 2 As shown, a second gas pipe 30b is pressed into the expanded diameter portion 13a2 of the U-shaped tube 13 at one end of the heat transfer tube 12 and is connected to the expanded diameter portion 13a2 by brazing. Additionally, although not shown in the figure, a second liquid pipe 20b is connected to the other end of the heat transfer tube 12 by brazing (see reference). Figure 1 ).

[0053] In addition, the second gas piping 30b is connected to one end and the other end of the heat transfer tube 12 respectively (see reference). Figure 2 ) and second liquid piping 20b (refer to Figure 1 This is equivalent to "refrigeration cycle piping".

[0054] Furthermore, the heat transfer tube 12 in this embodiment (refer to...) Figure 2 ), second gas piping 30b (refer to) Figure 2 ) and second liquid piping 20b (refer to Figure 1 It is made of aluminum or aluminum alloy.

[0055] Figure 3 This is a cross-sectional view of heat transfer tube 12.

[0056] like Figure 3 As shown, the heat transfer tube 12 is configured to have a base tube 15 made of aluminum or aluminum alloy and an anti-corrosion layer 16 formed on the outer surface of the base tube 15.

[0057] In this embodiment, the alternative corrosion-resistant layer 16 is formed by zinc sputtering. However, the alternative corrosion-resistant layer 16 is not limited to this, and can be formed by a metal layer containing a metal with a potential lower than that of the metal constituting the substrate tube 15. Specifically, the alternative corrosion-resistant layer 16 may also be formed by a cladding layer containing a zinc-aluminum alloy or a magnesium alloy, for example.

[0058] like Figure 2 As indicated by the light-colored shading, this chemical corrosion-resistant layer 16 is formed over the entire heat transfer tube 12 and also over the entire outer surface of the second gas piping 30b. Additionally, although not shown in the diagram, the chemical corrosion-resistant layer 16 also covers the second liquid piping 20b connected to the other end of the heat transfer tube 12 (see reference).Figure 1 It is formed by the entire outer surface of the surface.

[0059] Next, the indoor heat exchanger 4 (refer to...) Figure 1 (This will be explained.)

[0060] like Figure 1 As shown, the indoor heat exchanger 4 is roughly U-shaped in cross-section, covering the front and upper parts of the cross-flow fan 2, which serves as the blower.

[0061] Incidentally, the cross-flow fan 2 is positioned axially (with...) Figure 1 The indoor heat exchanger 4 is a longer cylindrical shape (in the direction perpendicular to the paper surface) and is formed in such a way that it is longer than the cross-flow fan 2 along the axial direction of the cross-flow fan 2.

[0062] The driven cross-flow fan 2 draws indoor air from the intake port (not shown) formed at the top of the casing 1 of the indoor unit 102, which is then passed through the indoor heat exchanger 4 and blown out of the casing 1 through the outlet 5. At this time, the indoor air is either cooled or heated according to the cooling or heating operation of the indoor heat exchanger 4. The indoor unit 102 blows out this blended air from the outlet 5.

[0063] Figure 4 This is a structural diagram illustrating the indoor heat exchanger 4. Furthermore, for ease of drawing, Figure 4 The middle section along the length of the indoor heat exchanger 4 has been omitted. Additionally, Figure 4 Is with Figure 1 A partial view of the indoor heat exchanger 4 on the connection side of the second liquid piping 20b shown.

[0064] like Figure 4 As shown, the indoor heat exchanger 4 has plate-shaped fins 21 and heat transfer tubes 22.

[0065] Multiple plate-shaped fins 21 are stacked at predetermined intervals along the thickness direction of the plate. The thickness direction of the fins 21 is parallel to that of the cross-flow fan 2 (see reference). Figure 1 ) axial (with) Figure 1 (Corresponding to the direction perpendicular to the paper surface). Furthermore, the fins 21 in this embodiment are formed of aluminum or aluminum alloy.

[0066] like Figure 4 As shown, the heat transfer tube 22 forms a meandering pipe 10b by a straight pipe portion 23a through which multiple fins 21 pass in the stacking direction and a return bend portion 23b arranged on both outer sides to sandwich the stacked fins 21 on the inner side.

[0067] Specifically, the heat transfer tube 22 has a plurality of U-shaped tubes 23 consisting of a pair of straight tube sections 23a and a return bend 23b connecting them, and a plurality of connecting tubes 24 forming only the return bend 23b of the pipe 10b.

[0068] In this embodiment, the U-shaped tube 23 is assumed to be a tube that bends a straight tube into a U-shape.

[0069] In addition, at the other end of the straight tube 23a through which multiple fins 21 pass, an enlarged diameter section 23a2 is formed, which has an inner diameter larger than that of the general section 23a1 that occupies most of the straight tube 23a.

[0070] The connecting tube 24 is in the shape of an arc, bent with the same curvature as the return bend 23b of the U-tube 23. The end of such a connecting tube 24 is pressed into the inside of the enlarged diameter portion 23a2 of the U-tube 23 and connected to the enlarged diameter portion 23a2 by brazing.

[0071] And, as Figure 4 As shown, a second liquid pipe 20b is pressed into the enlarged diameter portion 23a2 of the U-shaped tube 23 at one end of the heat transfer tube 22 and is connected to the enlarged diameter portion 23a2 by brazing. Additionally, although not shown in the figure, a second gas pipe 30b is connected to the other end of the heat transfer tube 22 by brazing (see reference). Figure 1 ).

[0072] In addition, the second liquid piping 20b is connected to one end and the other end of the heat transfer tube 22 respectively (see reference). Figure 4 ) and second gas piping 30b (refer to Figure 1 This is equivalent to "refrigeration cycle piping".

[0073] Furthermore, in this embodiment, the heat transfer tube 22 (refer to...) Figure 4 ), Second liquid piping 20b (refer to) Figure 4 ) and second gas piping 30b (refer to Figure 1 It is made of aluminum or aluminum alloy.

[0074] Figure 5A This is a cross-sectional view of the straight section 23a in the U-shaped tube 23.

[0075] like Figure 5A As shown, a corrosion-resistant layer 16 is formed on the outer surface of the straight pipe section 23a.

[0076] The alternative corrosion-resistant layer 16 is formed on the outer surface of the base tube 25, which is made of aluminum or an aluminum alloy, by zinc sputtering. However, the alternative corrosion-resistant layer 16 is not limited to this, and can be formed by a metal layer containing a metal with a lower potential than that of the metal constituting the base tube 25. Specifically, the alternative corrosion-resistant layer 16 can also be formed, for example, by a cladding containing a zinc-aluminum alloy or a magnesium alloy.

[0077] In addition, such as Figure 4 As indicated by the light-colored dotted shading, the anti-corrosion layer 16 is formed throughout the U-shaped tube 23, including the outer surface of the return bend 23b.

[0078] Figure 5B This is a cross-sectional view of the return bend 23b in the U-shaped tube 23.

[0079] like Figure 5B As shown, a covering layer 27 is formed in the return bend 23b.

[0080] The covering layer 27 is formed of heat-resistant synthetic rubber or synthetic resin.

[0081] Examples of heat-resistant synthetic rubbers include butyl rubber, chlorinated butyl rubber, brominated butyl rubber, and ethylene-propylene-diene copolymer rubber. Butyl rubber is preferred. Examples of heat-resistant synthetic resins include polytetrafluoroethylene (PTFE), polyethersulfone, polyetheretherketone (PEEK), polyamide-imide, and polyimide. Polytetrafluoroethylene (PTFE) is preferred.

[0082] As in Figure 4 As indicated by removing a portion of the covering layer 27, the covering layer 27 is formed in such a way that it completely covers the replacement anti-corrosion layer 16 throughout the return bend 23b in the U-shaped tube 23.

[0083] Figure 5C This is a cross-sectional view of the connecting pipe 24.

[0084] like Figure 5C As shown, connecting pipe 24 and Figure 2 Unlike the connecting pipe 14 of the outdoor heat exchanger 3 shown, the outer surface of the base pipe 25, which is made of aluminum or aluminum alloy, does not have a corrosion-resistant layer 16 (see reference). Figure 3 That is, the connecting pipe 24 is equivalent to "at least one of the return bends 23b disposed on the outer side of one side".

[0085] In addition, such as Figure 4 As shown, the return bend 23b of the connecting pipe 24 differs from that of the U-shaped pipe 23, and it also does not have a covering layer 27 (see reference). Figure 5B ).

[0086] and, Figure 5C The wall thickness ratio of the connecting pipe 24 (base pipe 25) shown by reference numeral T1 in the attached figure is... Figure 5A The base tube 25 in the U-shaped tube 23 shown by reference numeral T2 in the attached figure has a thicker wall (T1 > T2).

[0087] Additionally, connecting pipe 24 (refer to) Figure 5C Preferred by andFigure 2 The connecting pipe 14 of the outdoor heat exchanger 3 shown is composed of an aluminum alloy having a conversion corrosion-resistant layer 16. Specifically, Figure 5C The connecting pipe 24 shown preferably has a corrosion resistance of 35 days or more in a SWAAT test (Sea Water Acidified Test) in accordance with ASTM-G85-A3.

[0088] In addition, a conversion corrosion-resistant layer 16 and a cladding layer 27 are not formed on the second liquid pipe 20b connected to one end side of the heat transfer pipe 22. Figure 4 A conversion corrosion-resistant layer 16 (refer to Figure 2 ) and a cladding layer 27 (refer to Figure 1 ) are not formed on the second gas pipe 30b (refer to Figure 4 ) shown in the drawing. Figure 4

[0089] Also, the second liquid pipe 20b and the first liquid pipe 20a joined to the indoor heat exchanger 4 shown form a dissimilar metal joint portion 28 of a pipe composed of aluminum or an aluminum alloy and a pipe composed of copper. Also, with respect to the second gas pipe 30b and the first gas pipe 30a joined to the indoor heat exchanger 4 shown, a dissimilar metal joint portion 28 of a pipe composed of aluminum or an aluminum alloy and a pipe composed of copper is formed. Figure 1 Figure 1

[0090] Figure 6 is a longitudinal sectional view of the dissimilar metal joint portion 28 shown in Figure 1

[0091] As shown in Figure 6 , the dissimilar metal joint portion 28 has a pipe 28a composed of copper inserted inside a pipe 28b composed of aluminum or an aluminum alloy. These pipes 28a and 28b are joined to each other by brazing or the like. Also, the joint portion of the pipe 28a and the pipe 28b is covered by a sealing member 28c such as a heat shrinkable hose. According to such a dissimilar metal joint portion 28, the intervention of water at the contact portion of aluminum or an aluminum alloy and copper can be avoided, and galvanic corrosion can be prevented.

[0092] In addition, as shown in Figure 1 , a drain pan 17 is provided below the indoor heat exchanger 4.

[0093] The drain pan 17 forms an elongated tray extending along the length direction of the indoor heat exchanger 4 (a direction perpendicular to the paper surface of Figure 1 ). Also, the drain pan 17 receives the condensation water generated when the indoor heat exchanger 4 cools the surrounding air below the indoor heat exchanger 4.​​​​

[0094] Figure 7 is a structural explanatory view of the drain pan 17. Figure 7 is a partial perspective view showing the internal structure of the right end (the end of the paper face side) of the drain pan 17. Figure 1 , and the arrow shown in the drawing indicates the front-rear-up direction. Figure 7

[0095] As shown in the drawing, the bottom portion 17a of the drain pan 17 is inclined in such a manner that it is displaced downward more as it goes toward the rear side. And, in the rear of the bottom portion 17a, a downward drain pipe 19 is provided via a drain hole not shown. A drain hose not shown is connected to this drain pipe 19. Figure 7 In the drawing, the reference sign CW indicates the direction in which the condensation water flows along the downward slope of the bottom portion 17a. Figure 7

[0096] Further, although the drawing is omitted, a drain pipe 19 is also provided at the left end (the end of the paper face near side) of the drain pan 17. In addition, although the drain pipe 19 in the present embodiment is formed so as to be inclined downward, it can also be formed so as to be inclined toward the lower side of the vertical direction. Figure 1

[0097] <Effects>

[0098] Next, the effects of the air conditioner 100 of the present embodiment will be described.

[0099] Conventionally, an air conditioner in which a conversion anticorrosion layer is formed over the entire surface of a heat transfer pipe in an indoor heat exchanger is known (for example, refer to Patent Literature 1). However, when such a heat transfer pipe is exposed to air, white rust is sometimes generated on the surface of the heat transfer pipe. This tendency becomes significant particularly in an indoor heat exchanger used in an environment in which it is exposed to chloride ions contained in concrete, salt damage in the vicinity of a coast, and the like.

[0100] And, as described above, if this white rust is generated in the heat transfer pipe of the indoor heat exchanger, the white rust can contaminate the indoor, and there is also a possibility that it can clog a drain hole of the indoor unit.

[0101] The present inventors have found that, in the heat transfer pipe 22 in the indoor heat exchanger 4, at least in the straight pipe portion 23a that penetrates the fin 21 directly exposed to the flow of indoor air due to the cross-flow fan 2, it is necessary to apply the conversion anticorrosion layer 16, and on the other hand, in the connection pipe 24 disposed on the outer side of the fin 21 that is difficult to be directly exposed to the flow of indoor air, there is no necessity to apply the conversion anticorrosion layer 16.

[0102] ​​​In addition, the inventor of the present application has verified that the corrosion environment of indoor air is about 1 / 10 of that of outdoor air (outdoor air).

[0103] The present application is completed based on such a finding, and is an air conditioner 100 including: an indoor unit 102 having an indoor heat exchanger 4 that performs heat exchange between indoor air and a refrigerant; and an outdoor unit 101 having an outdoor heat exchanger 3 that performs heat exchange between outdoor air and the refrigerant, wherein a second liquid pipe 20b (refrigerant cycle pipe) and a second gas pipe 30b (refrigerant cycle pipe) formed of aluminum or an aluminum alloy are connected to one end side and the other end side of the indoor heat exchanger 4 and the outdoor heat exchanger 3, a conversion corrosion-resistant layer 16 is formed on the outer surface of the second liquid pipe 20b (refrigerant cycle pipe) and the second gas pipe 30b (refrigerant cycle pipe) disposed inside the outdoor unit 101 and connected to the outdoor heat exchanger 3, and the conversion corrosion-resistant layer 16 is not formed on the outer surface of the second liquid pipe 20b (refrigerant cycle pipe) and the second gas pipe 30b (refrigerant cycle pipe) disposed inside the indoor unit 102 and connected to the indoor heat exchanger 4.

[0104] According to the air conditioner 100, the conversion corrosion-resistant layer 16 is not formed on the outer surface of the second liquid pipe 20b (refrigerant cycle pipe) and the second gas pipe 30b (refrigerant cycle pipe) connected to the indoor heat exchanger 4, and thus white rust can be suppressed compared to the related art.

[0105] In addition, according to the air conditioner 100, white rust can be suppressed in the indoor heat exchanger 4 compared to the related art, and thus clogging of a drain hole can be prevented.

[0106] In addition, according to the air conditioner 100, the conversion corrosion-resistant layer 16 is formed on the outer surface of the second liquid pipe 20b (refrigerant cycle pipe) and the second gas pipe 30b (refrigerant cycle pipe) connected to the outdoor heat exchanger 3, and thus corrosion of the second liquid pipe 20b (refrigerant cycle pipe) and the second gas pipe 30b (refrigerant cycle pipe) can be prevented even in the outdoor heat exchanger 3 that is more likely to be exposed to salt damage and the like than the indoor heat exchanger 4.

[0107] In addition, according to the air conditioner 100, even if the conversion corrosion-resistant layer 16 is not formed on the outer surface of the second liquid pipe 20b (refrigerant cycle pipe) and the second gas pipe 30b (refrigerant cycle pipe) connected to the indoor heat exchanger 4, these second liquid pipe 20b (refrigerant cycle pipe) and second gas pipe 30b (refrigerant cycle pipe) can also exhibit predetermined corrosion resistance because they are disposed on the outer side of the fin 21 that is less likely to be directly exposed to indoor air.

[0108] Further, according to such an air conditioner 100, since the conversion corrosion preventive layer 16 can not be formed in the second liquid pipe 20b (refrigeration cycle pipe) and the second gas pipe 30b (refrigeration cycle pipe) connected to the indoor heat exchanger 4, it is possible to simplify the manufacturing process and reduce the manufacturing cost.

[0109] Further, the air conditioner 100 includes an indoor heat exchanger 4 that performs heat exchange between indoor air and refrigerant, and an outdoor heat exchanger 3 that performs heat exchange between outdoor air and refrigerant. The indoor heat exchanger 4 and the outdoor heat exchanger 3 include plate-shaped fins 11, 21 that are stacked in a plate thickness direction with a predetermined interval, and heat transfer pipes 12, 22 that are formed in a meandering shape by straight pipe portions 13a, 23a that pass through the fins 11, 21 in the stacking direction and return bent portions 13b, 23b that are arranged on both outer sides of the stacked fins 11, 21. The heat transfer pipes 12, 22 in the indoor heat exchanger 4 and the outdoor heat exchanger 3 are formed of aluminum or an aluminum alloy. In the return bent portion 13b of the heat transfer pipe 12 of the outdoor heat exchanger 3, a conversion corrosion preventive layer 16 is formed on at least an outer surface of the return bent portion 13b arranged on one outer side. In the return bent portion 23b of the heat transfer pipe 22 of the indoor heat exchanger 4, the conversion corrosion preventive layer 16 is not formed on at least an outer surface of the return bent portion 23b arranged on one outer side.

[0110] According to such an air conditioner 100, in the return bent portion 23b of the heat transfer pipe 22 of the indoor heat exchanger 4 arranged on both outer sides, the conversion corrosion preventive layer 16 is not formed on at least an outer surface of the return bent portion 23b arranged on one outer side, that is, an outer surface of the connection pipe 14. Therefore, compared with the related art, it is possible to suppress the generation of white rust.

[0111] Further, according to such an air conditioner 100, since the generation of white rust can be suppressed compared with the related art in the indoor heat exchanger 4, it is possible to prevent clogging of the drain hole.

[0112] Further, according to such an air conditioner 100, in the return bent portion 13b of the heat transfer pipe 12 of the outdoor heat exchanger 3 arranged on both outer sides, the conversion corrosion preventive layer 16 is formed on at least an outer surface of the return bent portion 13b arranged on one outer side. Therefore, even in the outdoor heat exchanger 3 that is more likely to be exposed to salt damage than the indoor heat exchanger 4, it is possible to prevent corrosion of the heat transfer pipe 12.

[0113] In addition, according to such an air conditioner 100, even in the return bent portion 23b of the heat transfer tube 22 of the indoor heat exchanger 4 disposed on the outer side of the both sides, at least the outer surface of the return bent portion 23b disposed on the outer side of one side is not formed with the conversion corrosion-resistant layer 16, and since the return bent portion 23b is disposed on the outer side of the fin 21 which is difficult to be directly exposed to the indoor air, the predetermined corrosion-resistant performance can be exhibited.

[0114] In addition, according to such an air conditioner 100, since the conversion corrosion-resistant layer 16 can be omitted at least from the return bent portion 23b disposed on the outer side of one side, the manufacturing process can be simplified, and the manufacturing cost can be reduced.

[0115] In addition, in the air conditioner 100, the conversion corrosion-resistant layer 16 can be formed on the outer surface of the straight pipe portion 23a of the heat transfer tube 22 and the return bent portion 23b disposed on the outer side of the other side in the indoor heat exchanger 4.

[0116] According to such an air conditioner 100, the straight pipe portion 23a having the conversion corrosion-resistant layer 16 is surrounded by the fin 21. Thus, the air conditioner 100 prevents the white rust generated from the conversion corrosion-resistant layer 16 from being scattered along with the air supply.

[0117] Further, in such an air conditioner 100, the return bent portion 23b of the U-shaped pipe 23 of the indoor heat exchanger 4 is disposed on the outer side of the fin 21 which is difficult to be directly exposed to the flow of the indoor air caused by the cross-flow fan 2, and the conversion corrosion-resistant layer 16 can be omitted. However, if the manufacturing process of forming the conversion corrosion-resistant layer 16 only on the straight pipe portion 23a in the U-shaped pipe 23 is considered to be complicated, the structure of the air conditioner 100 in which the conversion corrosion-resistant layer 16 is applied to the entire U-shaped pipe 23 is preferable.

[0118] In addition, in the air conditioner 100, the surface of the conversion corrosion-resistant layer 16 of the return bent portion 23b disposed on the outer side of the other side is formed with a coating layer 27 composed of synthetic rubber or synthetic resin.

[0119] According to such an air conditioner 100, the white rust generated on the return bent portion 23b can be more reliably suppressed by the coating layer 27.

[0120] In addition, in the air conditioner 100, a drain pan 17 which receives the condensed water is disposed below the indoor heat exchanger 4, and a drain pipe 19 which drains the condensed water from the drain pan 17 is extended downward from the bottom 17a of the drain pan 17.

[0121] According to such an air conditioner 100, the drainage of the condensed water from the drain pan 17 can be promoted, and thus the clogging of the drain hole caused by the white rust can be prevented.

[0122] Further, in the air conditioner 100, the wall thickness T1 of the connecting pipe 24 of the indoor heat exchanger 4 is thicker than the wall thickness T2 of the U-shaped pipe 23 (straight pipe portion 23a) of the U-shaped pipe 23 (straight pipe portion 23a) of the indoor heat exchanger 4 from which the thickness of the conversion corrosion preventive layer 16 is removed.

[0123] According to such an air conditioner 100, even the connecting pipe 24 not having the conversion corrosion preventive layer 16 can improve the pitting corrosion resistance compared to the U-shaped pipe 23 (straight pipe portion 23a).

[0124] Further, in the air conditioner 100, the connecting pipe 24 of the indoor heat exchanger 4 not having the conversion corrosion preventive layer 16 is formed of an aluminum alloy that is more corrosion resistant compared to the connecting pipe 14 of the outdoor heat exchanger 3 having the conversion corrosion preventive layer 16.

[0125] According to such an air conditioner 100, even the connecting pipe 24 not having the conversion corrosion preventive layer 16 can improve the pitting corrosion resistance compared to the connecting pipe 14 of the outdoor heat exchanger 3, and can suppress the generation of white rust.

[0126] The embodiments of the present application have been described above, but the present application is not limited to the embodiments described above, and can be implemented in various ways.

[0127] In the present embodiment, the case where the air conditioner 100 is provided with the wall-mounted indoor unit 102 has been described, but can be applied to, for example, an air conditioner provided with an indoor unit other than the wall-mounted indoor unit installed on a ceiling surface.

Claims

1. An air conditioner, comprising: an indoor unit having an indoor heat exchanger that performs heat exchange between indoor air and refrigerant; and an outdoor unit having an outdoor heat exchanger that performs heat exchange between outdoor air and refrigerant, characterized in that: a refrigerant cycle pipe formed of aluminum or an aluminum alloy is connected to one end side and the other end side of the indoor heat exchanger and the outdoor heat exchanger, a conversion corrosion-resistant layer is formed on an outer surface of the refrigerant cycle pipe disposed inside the outdoor unit and connected to the outdoor heat exchanger, and the conversion corrosion-resistant layer is not formed on an outer surface of the refrigerant cycle pipe disposed inside the indoor unit and connected to the indoor heat exchanger.

2. The air conditioner according to claim 1, characterized in that: a drain pan that receives condensed water is disposed below the indoor heat exchanger, and a drain pipe that discharges the condensed water from the drain pan extends downward from a bottom of the drain pan.

3. An air conditioner, comprising: an indoor heat exchanger that performs heat exchange between indoor air and refrigerant; and an outdoor heat exchanger that performs heat exchange between outdoor air and refrigerant, characterized in that: the indoor heat exchanger and the outdoor heat exchanger have: plate-shaped fins in which a plurality of fins are stacked at predetermined intervals in a plate thickness direction; and heat transfer pipes that form a meandering pipe route by straight pipe portions that pass through the plurality of fins in a stacking direction and return bends that sandwich the stacked fins inside and are disposed on both outer sides, the heat transfer pipes in the indoor heat exchanger and the outdoor heat exchanger are formed of aluminum or an aluminum alloy, at least an outer surface of the return bend disposed on one outer side among the return bends of the heat transfer pipe of the outdoor heat exchanger is formed with a conversion corrosion-resistant layer, and at least an outer surface of the return bend disposed on one outer side among the return bends of the heat transfer pipe of the indoor heat exchanger is not formed with a conversion corrosion-resistant layer.

4. The air conditioner according to claim 3, characterized in that: an outer surface of the straight pipe portion and the return bend disposed on the other outer side among the return bends of the heat transfer pipe in the indoor heat exchanger is formed with a conversion corrosion-resistant layer.

5. The air conditioner according to claim 4, characterized in that: a coating layer composed of synthetic rubber or synthetic resin is formed on a surface of the conversion corrosion-resistant layer of the return bend disposed on the other outer side.

6. The air conditioner according to claim 3, characterized in that: a drain pan that receives condensed water is disposed below the indoor heat exchanger, and a drain pipe that discharges the condensed water from the drain pan extends downward from a bottom of the drain pan.

7. The air conditioner according to claim 4, characterized in that: a wall thickness of the return bend disposed on one outer side among the return bends of the indoor heat exchanger, which is not formed with a conversion corrosion-resistant layer, is thicker than a wall thickness of the straight pipe portion of the indoor heat exchanger obtained by subtracting a thickness of the conversion corrosion-resistant layer from the straight pipe portion.

8. The air conditioner according to claim 3, characterized in that: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ The return bend part of the indoor heat exchanger, which is not formed with a conversion corrosion protection layer and is arranged on the outer side of one side, is formed of an aluminum alloy having a high corrosion resistance compared with the return bend part of the outdoor heat exchanger having a conversion corrosion protection layer.

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