Air conditioner indoor unit

Abstract

The indoor unit 102 of the air conditioner of the present invention is equipped with an intervening gas piping 30c (first pipe) that is arranged downstream of the indoor heat exchanger 3 during cooling operation, is made of aluminum or an aluminum alloy (first material), and has a refrigerant flowing therethrough, and a connecting gas piping 30b (second pipe) that is arranged downstream of the intervening gas piping 30c (first pipe) during cooling operation, is made of copper or a copper alloy (second material) different from the aluminum or aluminum alloy (first material), and has a refrigerant flowing therethrough, and the difference (Δ1=D1-D2) between the outer diameter D1 of the intervening gas piping 30c (first pipe) and the outer diameter D2 of the connecting gas piping 30b (second pipe) is greater than the difference (Δ2=D3-D4) between the inner diameter D3 of the intervening gas piping 30c (first pipe) and the inner diameter D4 of the connecting gas piping 30b (second pipe).

Description

[Technical field]

[0001] The present invention relates to an indoor unit of an air conditioner. [Background technology]

[0002] Conventionally, copper pipes have been mainly used in the refrigerant circuits of air conditioners. However, in recent years, aluminum pipes are sometimes used as part of the refrigerant circuits. The copper pipes and aluminum pipes in such refrigerant circuits are bonded with an adhesive or metallically joined. For example, Patent Document 1 discloses a joint pipe used in a refrigerant circuit in which a copper pipe and an aluminum pipe are eutectic-bonded. With this joint pipe, unnecessary substances generated during the joining are not discharged into the pipe, improving the reliability of the joint pipe. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2009-72820 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, a conventional joint pipe (for example, see Patent Document 1) may generate so-called refrigerant noise due to the flowing refrigerant. Therefore, when such a joint pipe is used in an indoor unit of an air conditioner, the generated refrigerant noise disrupts the quietness of the room.

[0005] The object of the present invention is to Due to the difference in inner diameter of the pipes made of different materials To provide an indoor unit for an air conditioner capable of suppressing the generation of refrigerant noise. [Means for solving the problem]

[0006] The indoor unit of the air conditioner of the present invention comprises a first pipe that is arranged downstream of an indoor heat exchanger during cooling operation, is made of a first material, and has a refrigerant flowing therethrough, and a second pipe that is arranged downstream of the first pipe during cooling operation, is made of a second material different from the first material, and has a refrigerant flowing therethrough, wherein the first pipe has a first joint side end and a first general portion connected to the first joint side end, and the second pipe has a second joint side end connected to the first joint side end and a second general portion connected to the second joint side end, The second joint side end portion is inserted inside the first joint side end portion, The thickness of the first general portion is greater than the thickness of the second general portion, the inner diameter of the first general portion is less than the outer diameter of the second general portion, the inner diameter of the second general portion is less than the outer diameter of the first general portion, and the difference between the outer diameter of the first general portion and the outer diameter of the second general portion is greater than the difference between the inner diameter of the first general portion and the inner diameter of the second general portion. Effect of the Invention

[0007] According to the indoor unit of the air conditioner of the present invention, Due to the difference in inner diameter of the pipes made of different materials The generation of refrigerant noise can be suppressed. [Brief description of the drawings]

[0008] [Figure 1] 1 is a configuration explanatory diagram of an air conditioner having an indoor unit according to an embodiment of the present invention. [Diagram 2] 2 is a partially enlarged perspective view of the internal structure of the indoor unit shown in FIG. 1. [Figure 3A] FIG. 2 is a partially enlarged perspective view of a gas pipe constituting the indoor unit according to the embodiment of the present invention. [Figure 3B] FIG. 3B is a cross-sectional view taken along line IIIB-IIIB of FIG. 3A. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, a form (embodiment) for carrying out an indoor unit of an air conditioner of the present invention will be described in detail with reference to the drawings as appropriate. Here, the overall configuration of the air conditioner will be described, and then the indoor unit will be described in more detail. <Air conditioner> Fig. 1 is a structural explanatory diagram of an air conditioner 100 having an indoor unit 102 according to an embodiment of the present invention. Fig. 2 is a partially enlarged perspective view of the internal structure of the indoor unit 102 shown in Fig. 1. As shown in FIG. 1, the air conditioner 100 includes an outdoor unit 101 and an indoor unit . An outdoor unit 101 installed outdoors exchanges heat between a refrigerant and outdoor air. An indoor unit 102 installed on a wall 104 inside a room exchanges heat between a refrigerant and indoor air.

[0010] During cooling operation, the air conditioner 100 takes in liquid refrigerant (including two-phase gas-liquid refrigerant) from the outdoor unit 101 via the liquid piping 20 to flow in the heat transfer tube 8 of the indoor heat exchanger 3 in the indoor unit 102. At this time, the indoor heat exchanger 3 functions as an evaporator to cool the surrounding air. Then, the gas refrigerant vaporized in the heat transfer tube 8 of the indoor heat exchanger 3 is sent to the outdoor unit 101 via the gas piping 30. The gas refrigerant sent to the outdoor unit 101 becomes liquid refrigerant (including two-phase gas-liquid refrigerant) via a compressor (not shown) of the outdoor unit 101 and an outdoor heat exchanger functioning as a condenser. This liquid refrigerant is sent again to the indoor unit 102 via the liquid piping 20.

[0011] During heating operation, the air conditioner 100 sends high-temperature, high-pressure gas refrigerant from the compressor to the indoor unit 102 via the gas piping 30 by switching the refrigerant flow path with a four-way valve (not shown) of the outdoor unit 101. At this time, the indoor heat exchanger 3 functions as a condenser to heat the surrounding air. Then, the liquid refrigerant (including two-phase gas-liquid refrigerant) condensed in the heat transfer tube 8 of the indoor heat exchanger 3 is sent to the outdoor unit 101 via the liquid piping 20. The liquid refrigerant sent to the outdoor unit 101 passes through an outdoor heat exchanger (not shown) functioning as a condenser of the outdoor unit 101 and a compressor, and becomes high-temperature, high-pressure gas refrigerant again and is sent to the indoor unit 102.

[0012] The indoor heat exchanger 3 in this embodiment includes fins 7 stacked at predetermined intervals and heat transfer tubes 8. This indoor heat exchanger 3 is a so-called fin-tube type heat exchanger having heat transfer tubes 8 in which a plurality of tubes penetrating the plurality of fins 7 in the stacking direction are connected in a meandering manner. The indoor heat exchanger 3 is an all-aluminum heat exchanger in which the fins 7 and heat transfer tubes 8 are made of aluminum or an aluminum alloy.

[0013] In this embodiment, the indoor heat exchanger 3 is formed in a substantially U-shape in cross section so as to cover the front and upper surface of the cross-flow fan 2, which is a blower. The indoor air that is sucked into the housing 1 by the driven cross-flow fan 2 through an inlet 4 formed in the upper part of the housing 1 passes through the indoor heat exchanger 3 and is blown out into the room from an outlet 5 formed in the front part of the housing 1. At this time, the indoor air is cooled or heated by the indoor heat exchanger 3 depending on whether it is cooling or heating. The indoor unit 102 blows out such conditioned air from the outlet 5.

[0014] In this air conditioner 100, the liquid piping 20 connecting the outdoor unit 101 and the indoor unit 102 includes an extension liquid piping 20a extending from the outdoor unit 101 side via the flare nut connection part 11, and a connection liquid piping 20b extending from the tip of this extension liquid piping 20a further to the indoor unit 102 side via the flare nut connection part 11. In addition, the liquid piping 20 further includes an intervening liquid piping 20c (see FIG. 2) that is interposed between the tip of the connecting liquid piping 20b and the indoor unit 102, as described later.

[0015] As shown in FIG. 1, the gas piping 30 includes an extension gas piping 30a extending from the outdoor unit 101 side via a flare nut connection portion 11, and a connection gas piping 30b extending from the tip of the extension gas piping 30a further to the indoor unit 102 side via the flare nut connection portion 11. In addition, the gas pipe 30 further includes an intermediate gas pipe 30c (see FIG. 2) that is interposed between the tip of the connection gas pipe 30b and the indoor unit 102, as described later.

[0016] These connecting liquid pipes 20b (see Figure 1) and intervening liquid pipes 20c (see Figure 2), as well as the connecting gas pipes 30b (see Figure 1) and intervening gas pipes 30c (see Figure 2), are drawn into the room through holes 105 (see Figure 1) formed in the wall 104 (see Figure 1). 2, the intervening liquid pipe 20c connected to the connecting liquid pipe 20b in the indoor unit 102 is connected to one end of the heat transfer pipe 8. The intervening gas pipe 30c connected to the connecting gas pipe 30b in the indoor unit 102 is connected to the other end of the heat transfer pipe 8. In FIG. 2, for convenience of drawing, only a part of the heat transfer tube 8 is shown by hidden lines.

[0017] The liquid piping 20 (see Figures 1 and 2) consisting of the extension liquid piping 20a (see Figure 1), the connecting liquid piping 20b (see Figure 1), and the intervening liquid piping 20c (see Figure 2) as described above, and the gas piping 30 (see Figures 1 and 2) consisting of the extension gas piping 30a (see Figure 1), the connecting gas piping 30b (see Figure 1), and the intervening gas piping 30c (see Figure 2) are formed in part from an aluminum pipe and the remaining parts except for that part are formed from a copper pipe, as described below.

[0018] <Indoor unit> Next, the indoor unit 102 of this embodiment will be described in more detail. Of the pipes constituting the liquid pipe 20 shown in FIGS. 1 and 2, the extension liquid pipe 20a (see FIG. 1) and the connection liquid pipe 20b (see FIG. 1) are made of copper pipes. On the other hand, the intermediate liquid pipe 20c (see FIG. 2) is made of an aluminum pipe.

[0019] Among the pipes constituting the gas pipe 30 shown in FIGS. 1 and 2, the extension gas pipe 30a (see FIG. 1) and the connection gas pipe 30b (see FIG. 1) are made of copper pipes. On the other hand, the intermediate gas pipe 30c (see FIG. 2) is made of an aluminum pipe. The gas piping 30 having the intermediate gas piping 30c and the connecting gas piping 30b is disposed downstream of the indoor heat exchanger 3 during cooling operation, as described above. Also, the connecting gas piping 30b is disposed downstream of the intermediate gas piping 30c during cooling operation, as described above.

[0020] That is, in such an indoor unit 102, the intermediate gas pipe 30c (see FIG. 2) made of aluminum or an aluminum alloy (first material) corresponds to the "first pipe." Also, the connecting gas pipe 30b (see FIG. 1) made of copper or a copper alloy (second material) constitutes the "second pipe." In this embodiment, the extension gas pipe 30a (see FIG. 1) and the connection gas pipe 30b (see FIG. 1) are made of copper pipes having the same inner diameter, outer diameter, and wall thickness.

[0021] Fig. 3A is a partially enlarged perspective view of the gas pipe 30 constituting the indoor unit 102 (see Fig. 2) according to this embodiment. Fig. 3B is a cross-sectional view taken along line IIIB-IIIB of Fig. 3A. In FIG. 3A, the extension gas pipe 30a (see FIG. 1), which constitutes the gas pipe 30 together with the connection gas pipe 30b, is omitted for convenience of drawing. As shown in FIG. 3A, the gas pipe 30 has an intermediate gas pipe 30c (first pipe) made of an aluminum pipe, and a connecting gas pipe 30b (second pipe) made of a copper pipe.

[0022] 3B, in this gas pipe 30, a joint end 30b2 of a connection gas pipe 30b (second pipe) is inserted inside a joint end 30c2 of an intermediate gas pipe 30c (first pipe). The joint end 30c2 of the intermediate gas pipe 30c (first pipe) and the joint end 30b2 of the connection gas pipe 30b (second pipe) are connected by eutectic bonding.

[0023] The joint end 30b2 of the connection gas pipe 30b (second pipe) has the same outer diameter as the general portion 30b1 of the connection gas pipe 30b (second pipe). Furthermore, in this gas piping 30, as shown in FIG. 3B, the difference (Δ1=D1-D2) between the outer diameter D1 of the general section 30c1 of the intervening gas piping 30c (first pipe) and the outer diameter D2 of the general section 30b1 of the connecting gas piping 30b (second pipe) is set to be larger than the difference (Δ2=D3-D4) between the inner diameter D3 of the general section 30c1 of the intervening gas piping 30c (first pipe) and the inner diameter D4 of the general section 30b1 of the connecting gas piping 30b (second pipe) (Δ1>Δ2).

[0024] In addition, the outer diameter D1 of the general portion 30c1 of the intervening gas pipe 30c (first pipe) is set to be larger than the outer diameter D2 of the general portion 30b1 of the connecting gas pipe 30b (second pipe), as shown in a specific example described later. Further, the thickness T1 of the general portion 30c1 of the intermediate gas pipe 30c (first pipe) is set to be thicker than the thickness T2 of the general portion 30b1 of the connecting gas pipe 30b (second pipe) (T1>T2).

[0025] In such a gas pipe 30, it is desirable that the inner diameter D3 of the intermediate gas pipe 30c (first pipe) is equal to or larger than the inner diameter D4 of the connecting gas pipe 30b (second pipe) (D3≧D4).

[0026] The above comparison of the pipe diameters and wall thicknesses of the intermediate gas pipe 30c (first pipe) and the connecting gas pipe 30b (second pipe) does not include the pipe diameters and wall thicknesses at the joints between the intermediate gas pipe 30c (first pipe) and the connecting gas pipe 30b (second pipe). In addition, although not shown, in the indoor unit 102 in which the intermediate gas pipe 30c (first pipe) branches on the indoor heat exchanger 3 side and is connected to the heat transfer pipe 8, only the intermediate gas pipe 30c (first pipe) that merges with the branch pipe downstream to form one path is compared in pipe diameter and wall thickness.

[0027] Returning to Figure 2, in the relationship between the heat transfer tube 8 and the intervening gas piping 30c (first tube), if the outer diameter of the general part of the heat transfer tube 8 is D5 and the inner diameter of the general part of the heat transfer tube 8 is D6, it is desirable that the difference between the outer diameter D5 of the heat transfer tube 8 and the outer diameter D1 of the intervening gas piping 30c (first tube) (Δ3 = D1 - D5) is greater than the difference between the inner diameter D6 of the heat transfer tube 8 and the inner diameter D3 of the intervening gas piping 30c (first tube) (Δ4 = D6 - D3) (Δ3 > Δ4).

[0028] Furthermore, if the thickness of the general part of the heat transfer tube 8 is T3, it is desirable that the outer diameter D1 of the intervening gas piping 30c (first tube) is larger than the outer diameter D5 of the heat transfer tube 8 (D1>D5), and the thickness T1 of the intervening gas piping 30c (first tube) is thicker than the thickness T3 of the heat transfer tube 8 (T1>T3). Moreover, it is desirable that the inner diameter D3 of the intermediate gas pipe 30c (first pipe) is equal to or smaller than the inner diameter D6 of the heat transfer pipe 8 (D3≦D6).

[0029] The comparison of the pipe diameters and wall thicknesses of the intervening gas piping 30c (first pipe) and the heat transfer tube 8 as described above does not include the pipe diameters and wall thicknesses of the intervening gas piping 30c (first pipe) and the heat transfer tube 8 at their mutual joints. In addition, when the heat transfer tube 8 (see FIG. 1) that passes through the fin 7 (see FIG. 1) and meanders back and forth is constructed by connecting multiple heat transfer tube 8 sections whose inner diameters are not uniform, the respective pipe diameters and wall thicknesses are compared, provided that the heat transfer tube 8 and the intervening gas piping 30c (first pipe) are connected by one path. In addition, if there are irregularities on the inside of the heat transfer tube 8 near the intervening gas piping 30c (first tube), the thickness T1 of the intervening gas piping 30c (first tube) will be compared with the thickness T3 of the heat transfer tube 8 at the thin part (recess).

[0030] The gas piping 30 and heat transfer tube 8 used in the refrigerant circuit of the air conditioner 100 (see FIG. 1) are selected so as to satisfy the above correlation, for example, from pipe sizes having an outer diameter of approximately 6.35 mm to 12.7 mm, for example, the intervening gas piping 30c (first tube), the connecting gas piping 30b (second tube), the extension gas piping 30a, and the heat transfer tube 8.

[0031] In this case, the intermediate liquid pipe 20c and the intermediate gas pipe 30c (first pipe) shown in FIG. 2 may be aluminum pipes having the same inner and outer diameters, or may be aluminum pipes having different diameters. In addition, for the connecting liquid pipe 20b and the extension liquid pipe 20a shown in FIG. 1, as well as the connecting gas pipe 30b (second pipe) and the extension gas pipe 30a, copper pipes having the same inner and outer diameters can be selected, or copper pipes different from each other can be selected.

[0032] Specific examples of the intervening liquid piping 20c, the intervening gas piping 30c (first pipe), the connecting liquid piping 20b, the extension liquid piping 20a, and the connecting gas piping 30b (second pipe) shown in Figures 1 and 2 are described below, but the present invention is not limited to these. The intermediate liquid pipe 20c may be an aluminum pipe having an outer diameter of 7.00 mm, an inner diameter of 5.20 mm, and a wall thickness of 0.90 mm. The connecting liquid pipe 20b and the extension liquid pipe 20a may be made of copper pipe having an outer diameter of 6.35 mm, an inner diameter of 5.15 mm, and a wall thickness of 0.60 mm.

[0033] The intermediate gas pipe 30c (first pipe) may be an aluminum pipe having an outer diameter D1 of 8.00 mm, an inner diameter D3 of 6.00 mm, and a wall thickness T1 of 1.00 mm. The connecting gas pipe 30b (second pipe) may be a copper pipe having an outer diameter D2 of 7.00 mm, an inner diameter D4 of 5.60 mm, and a wall thickness T2 of 0.70 mm. The heat transfer tube 8 may be an aluminum tube having an outer diameter D5 of 7.37 mm, an inner diameter D6 of 6.25 mm, and a wall thickness T3 of 0.56 mm.

[0034] The difference Δ1 between the outer diameter D1 of the intermediate gas pipe 30c (first pipe) and the outer diameter D2 of the connecting gas pipe 30b (second pipe) in this indoor unit 102 is 1.00 mm. Also, the difference Δ2 between the inner diameter D3 of the intermediate gas pipe 30c (first pipe) and the inner diameter D4 of the connecting gas pipe 30b (second pipe) in this indoor unit 102 is 0.40 mm. That is, the difference Δ1 in the outer diameters is larger than the difference Δ2 in the inner diameters (Δ1>Δ2).

[0035] In addition, in such an indoor unit 102, the difference (Δ3=D1−D5) between the outer diameter D5 of the heat transfer tube 8 and the outer diameter D1 of the intermediate gas pipe 30c (first tube) is 0.63 mm. The difference (Δ4=D6−D3) between the inner diameter D6 of the heat transfer tube 8 and the inner diameter D3 of the intermediate gas pipe 30c (first tube) is 0.25 mm. That is, the difference in the outer diameters Δ3 is greater than the difference in the inner diameters Δ4 (Δ3>Δ4).

[0036] Furthermore, in such an indoor unit 102, the inner diameter D3 (6.00 mm) of the intervening gas pipe 30c (first pipe) is larger than the inner diameter D4 (5.60 mm) of the connecting gas pipe 30b (second pipe) (D3>D4).

[0037] In addition, in such an indoor unit 102, the thickness T1 (1.00 mm) of the intermediate gas pipe 30c (first pipe) is thicker than the thickness T2 (0.70 mm) of the connecting gas pipe 30b (second pipe) (T1>T2). Also, the outer diameter D1 (8.00 mm) of the intermediate gas pipe 30c (first pipe) is larger than the outer diameter D2 (7.00 mm) of the connecting gas pipe 30b (second pipe) (D1>D2).

[0038] Furthermore, in such an indoor unit 102, the outer diameter D1 (8.00 mm) of the intermediate gas pipe 30c (first pipe) is larger than the outer diameter D5 (7.37 mm) of the heat transfer pipe 8 (D1>D5). Further, the wall thickness T1 (1.00 mm) of the intermediate gas pipe 30c (first pipe) is thicker than the wall thickness T3 (0.56 mm) of the heat transfer pipe 8 (T1>T3).

[0039] <Action and effect> Next, the effects and advantages of the indoor unit 102 of this embodiment will be described. In general, in a joint pipe between dissimilar material pipes such as copper pipes and aluminum pipes used in a refrigerant circuit (see, for example, Patent Document 1), the outer diameter and inner diameter of each of the dissimilar material pipes differ depending on the characteristics such as thermal conductivity and bending strength. In particular, in a joint pipe between a copper pipe and an aluminum pipe (see, for example, Patent Document 1), it is difficult to butt-join the pipes, and the connecting end of the copper pipe is inserted into the connecting end of the aluminum pipe, which is relatively thick, to join them. However, in such a joint pipe, a gap occurs between the inner diameters of the dissimilar material pipes at the joint between the dissimilar material pipes. Therefore, an indoor unit of an air conditioner using a conventional joint pipe may generate so-called refrigerant noise due to the flowing refrigerant.

[0040] In contrast, the indoor unit 102 of the air conditioner 100 of this embodiment is equipped with an intermediate gas piping 30c (first pipe) that is arranged downstream of the indoor heat exchanger 3 during cooling operation, is made of aluminum or aluminum alloy (first material), and has a refrigerant flowing inside, and a connecting gas piping 30b (second pipe) that is arranged downstream of the intermediate gas piping 30c (first pipe) during cooling operation, is made of copper or copper alloy (second material) different from aluminum or aluminum alloy (first material), and has a refrigerant flowing inside, and the difference (Δ1=D1-D2) between the outer diameter D1 of the intermediate gas piping 30c (first pipe) and the outer diameter D2 of the connecting gas piping 30b (second pipe) is greater than the difference (Δ2=D3-D4) between the inner diameter D3 of the intermediate gas piping 30c (first pipe) and the inner diameter D4 of the connecting gas piping 30b (second pipe) (Δ1>Δ2). According to such an indoor unit 102, the inner diameter of the intermediate gas pipe 30c (first pipe) and the inner diameter of the connection gas pipe 30b (second pipe) can be made closer to each other. The indoor unit 102 can reduce the pressure loss of the refrigerant flowing therethrough compared to the conventional case. As a result, the indoor unit 102 of this embodiment can suppress the generation of refrigerant noise.

[0041] Furthermore, in such an indoor unit 102, the difference (Δ3=D5-D1) between the outer diameter D5 of the heat transfer tube 8 and the outer diameter D1 of the intervening gas piping 30c (first tube) can be set to be greater than the difference (Δ4=D6-D3) between the inner diameter D6 of the heat transfer tube 8 and the inner diameter D3 of the intervening gas piping 30c (first tube) (Δ3>Δ4). According to such an indoor unit 102, the inner diameter D6 of the heat transfer tube 8 and the inner diameter D3 of the intermediate gas pipe 30c (first tube) can be made closer to each other. The indoor unit 102 can reduce the pressure loss of the refrigerant flowing therethrough compared to the conventional indoor unit. As a result, the indoor unit 102 of this embodiment can suppress the generation of refrigerant noise.

[0042] In addition, in such an indoor unit 102, the first material is aluminum or an aluminum alloy, and the second material is copper or a copper alloy. According to such an indoor unit 102, it is possible to construct an indoor heat exchanger 3 that is less expensive and has excellent thermal conductivity than conventional ones while using copper or copper alloys that are conventionally used in the main refrigerant circuit of the air conditioner 100.

[0043] In addition, in such an indoor unit 102, the intermediate gas pipe 30c (first pipe) and the connecting gas pipe 30b (second pipe) are eutectic-bonded. According to such an indoor unit 102, the intervening gas pipe 30c (first pipe) and the connecting gas pipe 30b (second pipe) can be joined by an intermetallic compound between the metal components of the intervening gas pipe 30c (first pipe) and the connecting gas pipe 30b (second pipe) without using a joining method such as brazing.

[0044] Furthermore, in such an indoor unit 102, the inner diameter D3 of the intervening gas pipe 30c (first pipe) can be set to be equal to or larger than the inner diameter D4 of the connecting gas pipe 30b (second pipe) (D3≧D4). According to such an indoor unit 102, the generation of refrigerant noise is further suppressed.

[0045] In addition, in such an indoor unit 102, the thickness T1 of the intermediate gas pipe 30c (first pipe) is set to be thicker than the thickness T2 of the general portion 30b1 of the connecting gas pipe 30b (second pipe) (T1>T2). In addition, in such an indoor unit 102, the outer diameter D1 of the intermediate gas pipe 30c (first pipe) is set to be larger than the outer diameter D2 of the connecting gas pipe 30b (second pipe) (D1>D2). According to such an indoor unit 102, the inner diameter D3 of the intermediate gas pipe 30c (first pipe) and the inner diameter D4 of the connection gas pipe 30b (second pipe) can be more reliably brought closer to each other. As a result, the indoor unit 102 of the present embodiment more reliably suppresses the generation of refrigerant noise.

[0046] In addition, in such an indoor unit 102, the outer diameter D1 of the intervening gas piping 30c (first pipe) can be set to be larger than the outer diameter D5 of the heat transfer pipe 8 (D1>D5), and the wall thickness T1 of the intervening gas piping 30c (first pipe) can be set to be thicker than the wall thickness T3 of the heat transfer pipe 8 (T1>T3). According to such an indoor unit 102, the inner diameter D6 of the heat transfer tube 8 and the inner diameter D3 of the intermediate gas piping 30c (first tube) can be more reliably brought closer to each other. As a result, the indoor unit 102 of the present embodiment can more reliably suppress the generation of refrigerant noise.

[0047] Although the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment and can be embodied in various forms. The indoor unit 102 in the above embodiment has been described as having a first tube made of aluminum or an aluminum alloy and a second tube made of copper or a copper alloy. However, the indoor unit 102 of the present invention is not limited to this, and may also be applied to an indoor unit having a first tube and a second tube made of another metal. [Explanation of symbols]

[0048] 30 Gas piping 30a Extension gas pipe 30b Connecting gas piping (second pipe) 30c Intervening gas piping (first pipe) 100 Air conditioner 102 Indoor unit

Claims

1. a first pipe that is arranged downstream of the indoor heat exchanger during cooling operation, that is made of a first material, and through which a refrigerant flows; a second pipe arranged downstream of the first pipe during cooling operation, made of a second material different from the first material, and through which a refrigerant flows; Equipped with An indoor unit of an air conditioner, wherein the inner diameter of the first pipe is smaller than the outer diameter of the second pipe, the inner diameter of the second pipe is smaller than the outer diameter of the first pipe, and the difference between the outer diameters of the first pipe and the second pipe is larger than the difference between the inner diameters of the first pipe and the second pipe.

2. 2. The indoor unit of an air conditioner according to claim 1, wherein a difference between an outer diameter of the heat transfer tube of the indoor heat exchanger and an outer diameter of the first tube is larger than a difference between an inner diameter of the heat transfer tube and an inner diameter of the first tube.

3. the first material is aluminum or an aluminum alloy; 2. The indoor unit of an air conditioner according to claim 1, wherein the second material is copper or a copper alloy.

4. 2. The indoor unit of an air conditioner according to claim 1, wherein the first pipe and the second pipe are joined by eutectic bonding.

5. 2. The indoor unit of an air conditioner according to claim 1, wherein the inner diameter of the first pipe is equal to or larger than the inner diameter of the second pipe.

6. 3. The indoor unit of an air conditioner according to claim 2, wherein the inner diameter of the first pipe is equal to or smaller than the inner diameter of the heat transfer pipe.

7. 2. The indoor unit of an air conditioner according to claim 1, wherein an outer diameter of the first pipe is larger than an outer diameter of the second pipe, and a wall thickness of the first pipe is thicker than a wall thickness of the second pipe.

8. 3. The indoor unit of an air conditioner according to claim 2, wherein an outer diameter of the first pipe is larger than an outer diameter of the heat transfer pipe, and a wall thickness of the first pipe is thicker than a wall thickness of the heat transfer pipe.

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