Indoor heat exchanger, air conditioning indoor unit, and manufacturing method of indoor heat exchanger

Abstract

To suppress remelting of a solder material when connecting a connection part of a plate laminate and a heat transfer pipe, while maintaining connection accuracy between the connection part and the heat transfer pipe.SOLUTION: An indoor heat exchanger includes: a heat exchanger (40A) having a fin (41) and a heat transfer pipe (42); and a plate laminate (50) which has a refrigerant flow passage (51) in communication with the heat transfer pipe (42), and a connection part (53) in communication with the refrigerant flow passage (51), to which the heat transfer pipe (42) is connected. The connection part (53) has an annular surface (72) continued to a joint surface (71) of the heat transfer pipe (42) and the connection part (53) and having an annular shape when viewed from the heat exchange part (40A) side in the axial direction of the heat transfer pipe (42). The annular surface (72) has a solder receiving part (73).SELECTED DRAWING: Figure 8

Description

[Technical field]

[0001] The present disclosure relates to an indoor heat exchanger, an air conditioning indoor unit, and a method for manufacturing an indoor heat exchanger. [Background technology]

[0002] Patent Document 1 discloses a refrigerant flow distributor used in an air conditioner. The refrigerant flow distributor includes an underplate in which a plurality of flow paths are formed, and an overplate laminated on the underplate. The overplate has a burring hole to which a connecting pipe is connected. It is disclosed that brazing of the underplate and the overplate, and brazing of the connecting pipe and the burring hole are simultaneously performed in a heat treatment furnace. In Patent Document 1, the connecting pipe is connected to a heat transfer pipe of a heat exchanger.

[0003] Patent Document 2 discloses a heat exchanger for an air conditioner indoor unit. The heat exchanger includes a heat exchanger body having fins and heat transfer tubes, and a refrigerant distributor that distributes and supplies refrigerant to a plurality of predetermined flow passage portions in the heat exchanger body, and the refrigerant distributor is composed of a plurality of plate-shaped members that are superimposed on each other, including a plate-shaped distribution member. The plurality of plate-shaped members are brazed and joined using a continuous heat treatment furnace. One of the plate-shaped members has a burring hole, and the burring hole is connected to the heat transfer tube. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2000-220914 A [Patent Document 2] JP 2006-125652 A Summary of the Invention [Problem to be solved by the invention]

[0005] As described in Patent Document 2, the heat exchange portion of the indoor heat exchanger generally includes fins and heat transfer tubes. The fins of the indoor heat exchanger are subjected to various surface treatments.

[0006] The plate stack and the heat transfer tube of the heat exchanger as described in Patent Document 1 and Patent Document 2 are generally connected by brazing. The plate stack and the heat transfer tube may be brazed in a heat treatment furnace as described in Patent Document 1. When the plate stack and the heat transfer tube are brazed in a heat treatment furnace, the heat exchanger including the fins and the plate stack are put into the heat treatment furnace together. If the fins are exposed to high temperatures, the surface treatment applied to the fins may be adversely affected.

[0007] In order to reduce the influence on the surface treatment of the fins, it is possible to braze the plate stack and the heat transfer tube by burner brazing. When performing burner brazing, the plate stack, which is relatively small, is usually placed on the upper side, and the heat exchange section is placed on the lower side. However, when performing burner brazing, the upper side is likely to become hotter than the lower side due to the influence of thermal convection, so there is a risk that the plates will also be heated by the heat of the burner. If the plates are heated, there is a risk that the brazing material joining the plates together will remelt.

[0008] To address this issue, it is conceivable to braze the heat exchanger section on the upper side and the plate stack on the lower side. However, this can lead to the risk that the brazing material will not flow between the connection section and the heat transfer tube, but will drip downward, resulting in poor connection accuracy.

[0009] An object of the present disclosure is to suppress remelting of the brazing material when connecting a connection portion of a plate stack to a heat transfer tube, while maintaining the connection accuracy between the connection portion and the heat transfer tube. [Means for solving the problem]

[0010] The first aspect is directed to an indoor heat exchanger. The indoor heat exchanger includes a plate stack (50, 250, 350, 450) having a heat exchange section (40A) having fins (41) and a heat transfer tube (42), a refrigerant flow path (51) communicating with the heat transfer tube (42), and a connection portion (53, 253, 353, 453) communicating with the refrigerant flow path (51) and to which the heat transfer tube (42) is connected, and the connection portion (53, 253, 353, 453) is a plate stack (50, 250, 350, 450) having a fin (41) and a heat transfer tube (42). The heat transfer tube (42) has an annular surface (72, 272, 372, 472) that is continuous with a joint surface (71, 271, 371, 471) between the heat transfer tube (42) and the heat exchange section (40A) in the axial direction of the heat transfer tube (42), and the annular surface (72, 272, 372, 472) has a brazing material receiving portion (73, 273, 373, 473) that receives the brazing material (70, 270, 370, 470).

[0011] In the first aspect, when the connection portion (53,253,353,453) and the heat transfer tube (42) are brazed in a posture in which the heat exchange portion (40A) is arranged on the upper side and the plate stack (50,250,350,450) is arranged on the lower side in order to suppress remelting of the brazing material of the plate stack (50,250,350,450), the brazing material receiver (73,273,373,473) can receive the molten brazing material (70,270,370,470). The brazing material receiver (73,273,373,473) can suppress the brazing material (70,270,370,470) from dripping downward, so that the connection accuracy between the connection portion (53,253,353,453) and the heat transfer tube (42) can be maintained at a high level.

[0012] In a second aspect, in the first aspect, the width between the inner edge and the outer edge of the annular surface (72, 272, 372, 472) is 0.6 mm to 1.5 mm.

[0013] In the second aspect, the brazing material receiving portion (73, 273, 373, 473) can be made as wide as possible, and the brazing material (70, 270, 370, 470) can be received by the brazing material receiving portion (73, 273, 373, 473) as much as possible. This suppresses dripping of the brazing material (70, 270, 370, 470) and maintains high connection accuracy between the connection portion (53, 253, 353, 453) and the heat transfer tube (42).

[0014] A third aspect is the first or second aspect, wherein an insertion distance between the connection portion (53, 253, 353, 453) and the heat transfer tube (42) is 2 mm or more.

[0015] In the third aspect, it is possible to flow as much brazing material as possible between the connection portion (53, 253, 453) and the heat transfer tube (42), thereby reducing the amount of brazing material (70, 270, 470) received by the brazing material receiver (73, 273, 473). This makes it possible to suppress dripping of the brazing material (70, 270, 470) and maintain high connection accuracy between the connection portion (53, 253, 453) and the heat transfer tube (42).

[0016] A fourth aspect is any one of the first to third aspects, wherein the heat transfer tube (42) is inserted inside the connection portion (53, 253).

[0017] In the fourth aspect, the brazing material (70, 270) can easily flow between the connection portion (53, 253) and the heat transfer tube (42), thereby reducing the amount of the brazing material (70, 270) received by the brazing material receiver (73, 273). This suppresses dripping of the brazing material (70, 270) and maintains high connection accuracy between the connection portion (53, 253) and the heat transfer tube (42).

[0018] In a fifth aspect, in the fourth aspect, the connection part (253) is a connection pipe and has a flare part (253a) at an end part on the heat exchange part (40A) side.

[0019] In the fifth aspect, the brazing material receiving portion (273) can be made as wide as possible by the flare portion (253a), thereby preventing the brazing material (270) from dripping. This makes it possible to maintain high connection accuracy between the connection portion (253) and the heat transfer tube (42).

[0020] In a sixth aspect, in any one of the first to third aspects, the connection portion (453) is a connection pipe and has a throttle portion (453a) at an end portion on the heat exchange portion (40A) side, and the throttle portion (453a) is inserted inside the heat transfer pipe (42).

[0021] In the sixth aspect, by providing the connection portion (453) with the narrowed portion (453a), it is possible to form the widest possible annular surface (472) in the portion other than the narrowed portion (453a). This makes it possible to make the brazing material receiving portion (473) as wide as possible, thereby suppressing dripping of the brazing material (470) and maintaining high connection accuracy between the connection portion (453) and the heat transfer tube (42).

[0022] The seventh aspect is directed to an indoor air conditioner. The indoor air conditioner includes the indoor heat exchanger of any one of the first to sixth aspects and a casing (31) that houses the indoor heat exchanger.

[0023] An eighth aspect is directed to a method for manufacturing an indoor heat exchanger. The indoor heat exchanger includes a plate stack (50, 250, 350, 450) having a heat exchange section (40A) having fins (41) and a heat transfer tube (42), a refrigerant flow path (51) communicating with the heat transfer tube (42), and a connection portion (53, 253, 353, 453) communicating with the refrigerant flow path (51) and to which the heat transfer tube (42) is connected, and the connection portion (53, 253, 353, 453) has an annular surface (72, 272, 372, 472) that is continuous with a joint surface (71, 271, 371, 471) between the connection portion (53, 253, 353, 453) and the heat transfer tube (42) and has an annular surface (72, 272, 372, 472) that is annular when viewed from the heat exchange section (40A) side in the axial direction of the heat transfer tube (42). A manufacturing method for an indoor heat exchanger includes a first step of placing the plate stack (50, 250, 350, 450) on a lower side and placing the heat exchange section (40A) on an upper side; a second step of placing a brazing material (70, 270, 370, 470) on the annular surface (72, 272, 372, 472); a third step of inserting one of the heat transfer tube (42) and the connection portion (53, 253, 353, 453) into the other of the heat transfer tube (42) and the connection portion (53, 253, 353, 453); and a fourth step of melting the brazing material (70, 270, 370, 470) with a burner to join the connection portion (53, 253, 353, 453) and the heat transfer tube (42).

[0024] In the eighth aspect, even if the plate stack (50, 250, 350, 450) is disposed on the lower side and the heat exchange section (40A) is disposed on the upper side, and the connection section (53, 253, 353, 453) and the heat transfer tube (42) are burner brazed, the annular surface (72, 272, 372, 472) can receive the molten brazing material (70, 270, 370, 470). This prevents the brazing material (70, 270, 370, 470) from dripping, and maintains high connection accuracy between the connection section (53, 253, 353, 453) and the heat transfer tube (42). [Brief description of the drawings]

[0025] [Figure 1]FIG. 1 is a piping diagram of an air conditioner having an indoor heat exchanger according to the first embodiment. [Diagram 2] FIG. 2 is a front view of the air conditioning indoor unit. [Diagram 3] FIG. 3 is a cross-sectional view of the air conditioning indoor unit taken along line II-II. [Figure 4] FIG. 4 is a front view showing the internal structure of the air conditioning indoor unit. [Diagram 5] FIG. 5 is a plan view showing the heat exchange unit. [Figure 6] FIG. 6 shows the plate stack as seen from the left side. [Figure 7] FIG. 7 is a cross-sectional view illustrating a coolant flow path of a plate stack. [Figure 8] FIG. 8 is a cross-sectional view showing a state in which the heat transfer tube and the front connection portion are connected to each other. [Figure 9] FIG. 9 is a cross-sectional view corresponding to line IX-IX in FIG. [Figure 10] FIG. 10 is a cross-sectional view showing a process of connecting a heat transfer tube and a front connection portion, illustrating a state before the heat transfer tube is inserted into the front connection portion. [Figure 11] FIG. 11 is a cross-sectional view showing a process of connecting a heat transfer tube and a front connection part, in which the heat transfer tube is inserted into the front connection part. [Figure 12] FIG. 12 is a cross-sectional view showing a process of connecting the heat transfer tube and the front connection portion, illustrating a state in which the heat transfer tube and the front connection portion are burner brazed. [Figure 13] FIG. 13 is a cross-sectional view showing a connection state between a heat transfer tube and a front connection portion in an indoor heat exchanger according to the second embodiment. [Figure 14] FIG. 14 is a cross-sectional view taken along line XIV-XIV in the figure. [Figure 15] FIG. 15 is a cross-sectional view showing a connection state between a heat transfer tube and a front connection portion in an indoor heat exchanger according to the third embodiment. [Figure 16] FIG. 16 is a cross-sectional view taken along line XVI-XVI in FIG. [Figure 17]FIG. 17 is a cross-sectional view showing a connection state between a heat transfer tube and a front connection portion in an indoor heat exchanger according to the fourth embodiment. [Figure 18] FIG. 18 is a cross-sectional view taken along line XVIII-XVIII in FIG. [Figure 19] FIG. 19 is a cross-sectional view showing a state in which a heat transfer tube and a front connection portion are burner brazed in an indoor heat exchanger according to the fourth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] Hereinafter, the embodiments of the present disclosure will be described in detail with reference to the drawings. Note that the present disclosure is not limited to the embodiments shown below, and various modifications are possible within the scope of the technical idea of ​​the present disclosure. Since each drawing is intended to conceptually explain the present disclosure, dimensions, ratios, or numbers may be exaggerated or simplified as necessary for easy understanding.

[0027] First Embodiment (1) Overall configuration of air conditioning system The first embodiment is an air conditioner (10) including a heat exchanger unit. The air conditioner (10) adjusts the temperature of air in an indoor space (I), which is a target space.

[0028] As shown in Fig. 1, the air conditioner (10) is an example of a refrigeration cycle device including a refrigerant circuit (11). The refrigerant circuit (11) is filled with a refrigerant. The refrigerant circuit (11) performs a refrigeration cycle by circulating the refrigerant.

[0029] The air conditioner (10) includes an outdoor unit (20), an indoor unit (30), a first connecting pipe (12), and a second connecting pipe (13). The air conditioner (10) is a pair type having one outdoor unit (20) and one indoor unit (30). The first connecting pipe (12) is a gas connecting pipe, and the second connecting pipe (13) is a liquid connecting pipe.

[0030] The outdoor unit (20) is installed outdoors and includes an outdoor casing (20a), and a compressor (21), an outdoor heat exchanger (22), an outdoor expansion valve (23), a four-way switching valve (24), and an outdoor fan (25) housed in the outdoor casing (20a).

[0031] The compressor (21) is a rotary compressor such as a swing piston type, rotary type, or scroll type. The outdoor heat exchanger (22) exchanges heat between the refrigerant and outdoor air. The outdoor heat exchanger (22) is a fin-and-tube type. The outdoor expansion valve (23) reduces the pressure of the refrigerant. The outdoor expansion valve (23) is an electronic expansion valve. The four-way switching valve (24) switches between a first state (a state shown by a solid line in FIG. 1) and a second state (a state shown by a dashed line in FIG. 1). In the first state, the four-way switching valve (24) communicates between the discharge portion of the compressor (21) and the gas end of the outdoor heat exchanger (22) and also communicates between the suction portion of the compressor (21) and the first connection pipe (12). The four-way switching valve (24) in the second state communicates the discharge portion of the compressor (21) with the first connection pipe (12) and also communicates the suction portion of the compressor (21) with the gas end of the outdoor heat exchanger (22). The outdoor fan (25) transports the air flowing through the outdoor heat exchanger (22). The outdoor fan (25) is a propeller fan.

[0032] The indoor unit (30) includes a casing (31), and an indoor heat exchanger (40), an indoor fan (32), and an indoor expansion valve (37) housed in the casing (31).

[0033] (2) Air conditioning indoor unit The indoor unit (30) which is an indoor air conditioner will be described in detail with reference to Figs. 2 to 4. The indoor unit (30) of the first embodiment is a wall-mounted type provided on a wall of the indoor space (I). Note that the terms "upper", "lower", "right", "left", "front", and "rear" described below correspond to the directions of the arrows shown in Figs. 2 and 3, and the left-right direction is based on the case where the indoor casing (31) is viewed from the front.

[0034] (2-1) Casing 2 and 3, the casing (31) is formed in a horizontally long box shape and has a front plate (31a), a rear plate (31b), an upper plate (31c), a lower plate (31d), a first side plate (31e), and a second side plate (31f).

[0035] The front plate (31a) is formed on the front side of the casing (31) and constitutes the front surface of the casing (31). The rear plate (31b) is formed on the rear side of the casing (31) and constitutes the rear surface of the casing (31). The upper plate (31c) is formed on the upper side of the casing (31) and constitutes the upper surface of the casing (31). The lower plate (31d) is formed on the lower side of the casing (31) and constitutes the lower surface of the casing (31). The first side plate (31e) is formed on the right side of the casing (31) and constitutes the right surface of the casing (31). The second side plate (31f) is formed on the left side of the casing (31) and constitutes the left surface of the casing (31).

[0036] An intake port (33) is formed in the upper plate (31c), and an exhaust port (34) is formed in the lower plate (31d). An air passage (P) is formed inside the casing (31) from the intake port (33) to the exhaust port (34). The intake port (33) extends in the longitudinal direction of the casing (31). The intake port (33) is an opening for taking air from the indoor space (I) into the air passage (P). An exhaust port (34) is formed in the lower plate (31d). The exhaust port (34) extends in the longitudinal direction of the casing (31). The exhaust port (34) is an opening for blowing air from the air passage (P) into the indoor space (I).

[0037] (2-2) Filter The indoor unit (30) includes a filter (35). The filter (35) is disposed on the rear side of the suction port (33) and upstream of the indoor heat exchanger (40). The filter (35) collects dust in the air sent from the suction port (33) to the indoor heat exchanger (40). The indoor unit (30) may include a dust removal mechanism that removes the dust collected by the filter (35).

[0038] (2-3) Heat exchanger unit The heat exchanger unit (U) includes one indoor heat exchanger (40) and one indoor expansion valve (37). The indoor heat exchanger (40) includes one heat exchanger body (B) and two plate stacks (50, 60). The heat exchanger body (B) of the indoor heat exchanger (40) is disposed so as to cross the air passage (P). The air passage (P) is divided into an upstream side and a downstream side of the heat exchanger body (B).

[0039] (2-4) Indoor fan The indoor fan (32) is disposed in the air passage (P). The indoor fan (32) is disposed in the air passage (P) downstream of the indoor heat exchanger (40). The indoor fan (32) is a crossflow fan. The indoor fan (32) has a fan rotor that extends in the longitudinal direction of the casing (31).

[0040] (2-5) Flap The indoor unit (30) has a flap (36) that adjusts the direction of air blown out of the air outlet (34). The flap (36) adjusts the air direction in the vertical direction. The indoor unit (30) may have a plurality of flaps (36). The flap (36) may adjust the air direction in the horizontal direction.

[0041] (3) Heat exchanger unit As described above, the heat exchanger unit (U) includes the indoor heat exchanger (40), the indoor expansion valve (37), the gas relay pipe (12a), and the liquid relay pipe (13a).

[0042] (3-1) Indoor heat exchanger The indoor heat exchanger (40) shown in Figures 3 to 6 includes a heat exchanger body (B) and a plate stack (50, 60) connected to the heat exchanger body (B). The indoor heat exchanger (40) is a fin-and-tube heat exchanger having fins (41) and heat transfer tubes (42). The indoor heat exchanger (40) exchanges heat between air and a refrigerant.

[0043] The heat exchanger body (B) has a plurality of fins (41) arranged in the longitudinal direction of the casing (31) and a plurality of heat transfer tubes (42) extending in the arrangement direction of the fins (41).

[0044] The arrangement direction of the fins (41) corresponds to the longitudinal direction (here, the left-right direction) of the casing (31). The fins (41) are rectangular plate-shaped having long sides and short sides. The thickness direction of the fins (41) corresponds to the arrangement direction of the fins (41). The multiple fins (41) are arranged at predetermined intervals in the thickness direction. This interval defines an air flow path. The material of the fins (41) is an aluminum alloy.

[0045] The fins 41 are surface-treated to improve surface tension before the heat transfer tubes 42 are inserted through the fins 41.

[0046] The heat transfer tubes (42) are straight tubes. The heat transfer tubes (42) are made of an aluminum alloy. The heat transfer tubes (42) may be made of a copper alloy. A refrigerant flow path is formed inside the heat transfer tubes (42). The heat transfer tubes (42) extend parallel to one another so as to penetrate the fins (41). One end of the heat transfer tube (42), which is a right end, protrudes to the right of the fin (41). One end of the heat transfer tube is connected to the plate stack (50, 60). Of the other ends of the heat transfer tubes (42), which are left ends, the left ends of two adjacent heat transfer tubes (42) are connected to each other by a U-shaped tube (48). The two adjacent heat transfer tubes (42) and the U-shaped tube (48) connecting them are formed integrally and seamlessly.

[0047] The indoor heat exchanger (40) of the first embodiment has a front heat exchange section (40A) which is a first heat exchange section, and a rear heat exchange section (40B) which is a second heat exchange section. The front heat exchange section (40A) is located toward the front side of the casing (31), and the rear heat exchange section (40B) is located toward the rear side of the casing (31). The front heat exchange section (40A) and the rear heat exchange section (40B) are arranged in a direction perpendicular to both the up-down direction and the axial direction of the heat transfer tube (42), i.e., in the front-rear direction, with the indoor fan (32) between them.

[0048] The front heat exchange section (40A) includes a front main heat exchange section (43), a first auxiliary heat exchange section (44), and a second auxiliary heat exchange section (45).

[0049] The front main heat exchange section (43) is disposed in the front heat exchange section (40A) closer to the indoor fan (32). The front main heat exchange section (43) has an outer shape formed in a V-shape when viewed in the longitudinal direction of the heat transfer tube (42). The tip of the V-shape faces forward.

[0050] The front main heat exchange section (43) is composed of a first front main heat exchange section (43a) extending obliquely upward toward the rear side, and a second front main heat exchange section (43b) extending obliquely downward toward the rear side. The first front main heat exchange section (43a) is located at an upper part of the front main heat exchange section (43), and the second front main heat exchange section (43b) is located at a lower part of the front main heat exchange section (43). The lower end of the first front main heat exchange section (43a), i.e., the lower short side of the fin (41), contacts the long side of the fin (41) of the second front main heat exchange section (43b) (strictly speaking, the upper end portion of the long side of the fin (41)). The angle between the rear long side of the first front main heat exchange section (43a) and the upper long side (the side closer to the first front main heat exchange section (43a)) of the second front main heat exchange section (43b) is approximately 90° to 110°. The fins (41) constituting the first front main heat exchange section (43a) and the fins (41) constituting the second front main heat exchange section (43b) may be integral with each other or may be separate from each other.

[0051] The first auxiliary heat exchange section (44) is provided on the inlet side (front side) of the first front main heat exchange section (43a). The lengths of the long and short sides of the fins (41) of the first auxiliary heat exchange section (44) are shorter than the lengths of the long and short sides of the fins (41) of the first front main heat exchange section (43a).

[0052] The second auxiliary heat exchange section (45) is provided on the inlet side (front side) of the second front main heat exchange section (43b). The lengths of the long and short sides of the fins (41) of the second auxiliary heat exchange section (45) are shorter than the lengths of the long and short sides of the fins (41) of the second front main heat exchange section (43b).

[0053] The rear heat exchange section (40B) has a rear main heat exchange section (46) and a third auxiliary heat exchange section (47). The rear main heat exchange section (46) is disposed closer to the indoor fan (32) in the rear heat exchange section (40B).

[0054] The third auxiliary heat exchange section (47) is provided on the inflow side (rear side) of the rear main heat exchange section (46). The lengths of the long sides and the short sides of the fins (41) of the third auxiliary heat exchange section (47) are shorter than the lengths of the long sides and the short sides of the fins (41) of the rear main heat exchange section (46). The number of stages and rows of the heat transfer tubes (42) of the third auxiliary heat exchange section (47) is smaller than the number of stages and rows of the heat transfer tubes (42) of the rear main heat exchange section (46).

[0055] The plate stack (50, 60) is disposed on the right side of the rightmost fin (41) in parallel to the fin (41). The plate stack (50, 60) is connected to one end of the heat transfer tube (42). As shown in FIG. 5, the plate stack (50, 60) includes a front plate stack (50) connected to the heat transfer tube (42) of the front heat exchange section (40A) and a rear plate stack (60) connected to the heat transfer tube (42) of the rear heat exchange section (40B). The front plate stack (50) is disposed so as to overlap the front heat exchange section (40A) in the axial direction of the heat transfer tube (42). The rear plate stack (60) is disposed so as to overlap the rear heat exchange section (40B) in the axial direction of the heat transfer tube (42). The plate stacks (50, 60) have therein refrigerant flow paths (51, 61) which communicate with the heat transfer tubes (42). The front plate stack (50) and the rear plate stack (60) will be described in detail later.

[0056] (3-2) Indoor expansion valve, gas relay pipe, liquid relay pipe The indoor expansion valve (37) is an electronic expansion valve with a variable opening degree. As shown in Fig. 5, the indoor expansion valve (37) is disposed on the right side of the plate stack (50, 60). The indoor expansion valve (37) is connected to the front plate stack (50) via a first internal pipe (38) and is connected to the rear plate stack (60) via a second internal pipe (39). The first internal pipe (38) and the second internal pipe (39) are an example of refrigerant pipes that connect the refrigerant flow path (51) of the front plate stack (50) and the refrigerant flow path (61) of the rear plate stack (60).

[0057] One end of the gas relay pipe (12a) is connected to the rear plate assembly (60). The other end of the gas relay pipe (12a) is connected to the first connection pipe (12) via a joint. One end of the liquid relay pipe (13a) is connected to the front plate assembly (50). The other end of the liquid relay pipe (13a) is connected to the second connection pipe (13) via a joint.

[0058] (4) Plate stack The plate stack (50, 60) will be described in detail with reference to FIGS.

[0059] (4-1) Front plate assembly The front plate stack (50) includes a front main body portion (52) having a refrigerant flow path (51) therein, a plurality of front connection portions (53) communicating with the refrigerant flow path (51) and to which a plurality of heat transfer tubes (42) of the front heat exchange section (40A) are connected, a front relay portion (54) to which the first internal piping (38) is connected, and a liquid end portion (55) communicating with the second connection piping (13) via a liquid relay pipe (13a).

[0060] (4-1-1) Front main body part As shown in FIG. 5, the front main body portion (52) is a thick plate-like member formed by stacking five front plates. The stacking direction of the front plates is the same as the axial direction of the heat transfer tubes (42). In the front plate stack (50), a first front plate (521), a second front plate (522), a third front plate (523), a fourth front plate (524), and a fifth front plate (525) are stacked in order from the side closest to the front heat exchange section (40A). The second front plate (522), the third front plate (523), and the fourth front plate (524) are intermediate plates sandwiched between the first front plate (521) and the fifth front plate (525). The five front plates are flat plate-like members having the same outer edge shape. In the first embodiment, the material of each of the front plates is an aluminum alloy. The material of each of the front plates (521-525) is not limited to aluminum alloy, and may be, for example, copper alloy or stainless steel. The first front plate (521) and the fifth front plate (525) have a thickness of, for example, 1.5 mm. The second front plate (522), the third front plate (523) and the fourth front plate (524) have a thickness of, for example, 3.0 mm. The front plates are joined to each other by furnace brazing. Note that the number of front plates is just an example, and the number of front plates may be four or less, or six or more. Hereinafter, when there is no need to distinguish between the front plates, they will simply be referred to as front plates.

[0061] The front main body portion (52) has a first left side surface (52c) which is a surface on the front heat exchanger portion (40A) side (here, the left side) in the axial direction of the heat transfer tube (42), a first right side surface (52d) which is a surface opposite to the first left side surface (52c) in the axial direction, and a first peripheral surface (52e) which is a peripheral surface extending between the first left side surface (52c) and the first right side surface (52d). The first left side surface (52c) is a surface of the first front plate (521) on the front heat exchanger portion (40A) side. The first right side surface (52d) is a surface of the fifth front plate (525) opposite to the fourth front plate (524). The first peripheral surface (52e) is a surface formed by the side surfaces of the front plates (521, 522, 523, 524, 525). The first left side surface (52c) corresponds to a predetermined surface.

[0062] (4-1-2) Front connection part The front connection part (53) is a circular tube that protrudes from the first left side surface (52c) toward the front heat exchange part (40A). The material of the front connection part (53) is an aluminum alloy. The material of the front connection part (53) is not limited to an aluminum alloy, and may be, for example, a copper alloy or stainless steel. The length of the front connection part (53) from the first left side surface (52c) is, for example, 5 mm or more. The inner diameter of the front connection part (53) is slightly larger than the outer diameter of the heat transfer tube (42).

[0063] The thickness of the front connection part (53) is equal to or thinner than the thickness of the first front plate (521). The thickness of the front connection part (53) is 0.6 mm to 1.5 mm.

[0064] As shown in FIG. 8, one end of the front connection part (53) is located outside the corresponding heat transfer tube (42). In other words, the heat transfer tube (42) is inserted inside the front connection part (53). The insertion distance between the front connection part (53) and the heat transfer tube (42) is 2 mm or more. The front connection part (53) is joined to the corresponding heat transfer tube (42) by burner brazing. The inner peripheral surface of the front connection part (53) has a joint surface (71) which is a connection portion with the heat transfer tube (42). The outer peripheral surface of the heat transfer tube (42) and the joint surface (71) are spaced apart from each other, and the brazing material (70) is located between the outer peripheral surface of the heat transfer tube (42) and the joint surface (71). In the axial direction of the front connection part (53), the length of the joint surface (71) is equal to or slightly shorter than the insertion distance between the front connection part (53) and the heat transfer tube (42). The brazing material 70 has a melting point lower than those of the heat transfer tube 42 and the front connection portion 53. The brazing material 70 is, for example, an aluminum brazing material. The brazing material 70 has a Si content of 10% to 13% by mass and a Mg content of 0.1% or less by mass.

[0065] 9, the end face of the front connection part (53) on the front heat exchange part (40A) side is an annular surface (72) that is annular when viewed from the front heat exchange part (40A) side in the axial direction of the heat transfer tube (42). The annular surface (72) is continuous with the joint surface (71). The annular surface (72) surrounds the heat transfer tube (42) from the outside. The width between the inner edge and the outer edge of the annular surface (72) is equal to the thickness of the front connection part (53). Specifically, the width between the inner edge and the outer edge of the annular surface (72) is 0.6 mm to 1.5 mm.

[0066] At least a portion of the annular surface (72) is a brazing material receiving portion (73) that receives the molten brazing material (70).

[0067] The other end of the front connection part (53) is inserted into a through hole formed in the first front plate (521) and joined to the first front plate (521) by brazing. Note that the front connection part (53) and the first front plate (521) may be molded seamlessly as a single piece by, for example, casting or sintering metal powder using a 3D printer.

[0068] (4-1-3) Front relay section, liquid end As shown in FIG. 6, the front relay portion (54) is a circular pipe. The front relay portion (54) is provided on the fifth front plate (525) and disposed on the first right side surface (52d) of the front main body portion (52). In the front plate stack (50), the first internal piping (38) is connected to the first right side surface (52d) of the front plate stack (50). The front relay portion (54) is located in a rear portion of the boundary between the first overlapping portion (52a) and the second overlapping portion (52b) of the fifth front plate (525). The amount of protrusion of the front relay portion (54) from the first right side surface (52d) is smaller than the amount of protrusion of the front connection portion (53) from the first left side surface (52c). The front relay portion (54) is joined to an end of the front first internal piping (38) by brazing.

[0069] The liquid end portion (55) is a circular pipe. The liquid end portion (55) is provided on the fifth front plate (525) and disposed on the first right side surface (52d) of the front main body portion (52). The liquid end portion (55) is located in the second overlapping portion (52b) of the fifth front plate (525). The amount by which the liquid end portion (55) protrudes from the first right side surface (52d) is the same as the amount by which the front relay portion (54) protrudes from the first right side surface (52d). The liquid end portion (55) is joined to the end portion of the liquid relay pipe (13a) by brazing.

[0070] At the position of the liquid end (55), the refrigerant flow path (51) of the front plate stack (50) extends straight in the stacking direction of the front plates without being connected to other refrigerant flow paths (51). The refrigerant flow path (51) at the position of the liquid end (55) communicates with the heat transfer tube (42) located lowest in the second auxiliary heat exchange section (45).

[0071] The front relay part (54) and the liquid end part (55) are molded seamlessly and integrally with the fifth front plate (525). More specifically, the front relay part (54), the liquid end part (55), and the fifth front plate (525) are configured from a single member. The front relay part (54) and the liquid end part (55) are molded integrally with the fifth front plate (525) by burring the fifth front plate (525). The front relay part (54) and the liquid end part (55) may be molded integrally with the fifth front plate (525) by casting or sintering metal powder using a 3D printer.

[0072] (4-2) Rear plate assembly The rear plate stack (60) includes a rear main body portion (62) having a refrigerant flow path (61) therein, a plurality of rear connection portions (63) that communicate with the refrigerant flow path (61) and to which the plurality of heat transfer tubes (42) of the rear heat exchange section (40B) are connected, a rear relay portion (64) to which the second internal piping (39) is connected, and a gas end portion (65) that communicates with the first connection piping (12) via a gas relay pipe (12a).

[0073] (4-2-1) Rear body part The rear body portion (62) has basically the same configuration as the front body portion (52), except that the shape of the outer edge of the plate as viewed in the axial direction of the heat transfer tubes (42) and the internal refrigerant flow paths (61) are different from those of the front body portion (52). As shown in FIG. 5, the rear body portion (62) is a thick plate-like member formed by stacking five rear plates. The stacking direction of the rear plates is the same as the axial direction of the heat transfer tubes (42). In the rear plate stack (60), a first rear plate (621), a second rear plate (622), a third rear plate (623), a fourth rear plate (624), and a fifth rear plate (625) are stacked in order from the side closest to the rear heat exchange section (40B). The second rear plate (622), the third rear plate (623), and the fourth rear plate (624) are intermediate plates sandwiched between the first rear plate (621) and the fifth rear plate (625). In the first embodiment, the rear plates are made of an aluminum alloy. The material of each of the rear plates (621-625) is not limited to an aluminum alloy, and may be, for example, a copper alloy or stainless steel. The first rear plate (621) and the fifth rear plate (625) have a thickness of, for example, 1.5 mm. The second rear plate (622), the third rear plate (623), and the fourth rear plate (624) have a thickness of, for example, 3.0 mm. The five rear plates are joined together by furnace brazing. The number of rear plates is just an example, and the number of rear plates may be four or less, or six or more. The number of front plates and the number of rear plates may be different. Hereinafter, when there is no need to distinguish between the respective rear plates, they will simply be referred to as rear plates.

[0074] The rear main body portion (62) has a second left side surface (62a) which is a surface on the rear heat exchange section (40B) side in the axial direction of the heat transfer tube (42), a second right side surface (62b) which is a surface on the opposite side to the second left side surface (62a) in the axial direction, and a second peripheral surface (62c) which is a peripheral surface extending between the second left side surface (62a) and the second right side surface (62b). The second left side surface (62a) is a surface of the first rear plate (621) on the rear heat exchange section (40B) side. The second left side surface (62a) is a surface of the fifth rear plate (625) on the opposite side to the fourth rear plate (624). The second peripheral surface (62c) is a surface formed by the side surfaces of the respective rear plates (621, 622, 623, 624, 625).

[0075] (4-2-2) Rear connection part The rear connection part (63) is a circular tube that protrudes from the second left side surface (62a) toward the rear heat exchange part (40B). The material of the rear connection part (63) is an aluminum alloy. The material of the rear connection part (63) is not limited to an aluminum alloy, and may be, for example, a copper alloy or stainless steel. The length of the rear connection part (63) from the second left side surface (62a) is, for example, 5 mm or more. The inner diameter of the rear connection part (63) is slightly larger than the outer diameter of the heat transfer tube (42).

[0076] The thickness of the rear connection portion (63) is equal to or thinner than the thickness of the first rear plate (621). The thickness of the rear connection portion (63) is 0.6 mm to 1.5 mm.

[0077] One end of the rear connection part (63) is inserted into the inside of the open end of the corresponding heat transfer tube (42) and joined to the corresponding heat transfer tube (42) by burner brazing. Like the front connection part (53), one end of the rear connection part (63) has a joint surface which is a joint portion with the heat transfer tube (42). An edge of the rear connection part (63) is continuous with the joint surface and has an annular surface which is annular when viewed from the rear heat exchange part (40B) side in the axial direction of the heat transfer tube (42). The annular surface has a braze receiving portion which receives molten brazing material.

[0078] The other end of the rear connection part (63) is inserted into a through hole formed in the first rear plate (621) and joined to the first rear plate (621) by brazing. The rear connection part (63) and the first rear plate (621) may be molded seamlessly as a single piece by, for example, casting or sintering metal powder using a 3D printer.

[0079] (4-2-3) Rear relay section, gas end The rear relay portion (64) is a circular pipe. As shown in FIG. 6, the rear relay portion (64) is provided on the fifth rear plate (625) and disposed on the second right side surface (62b) of the rear main body portion (62). That is, in the rear plate stack (60), the second internal pipe (39) that connects the refrigerant flow path (51) of the front plate stack (50) and the refrigerant flow path (61) of the rear plate stack (60) is connected to the second right side surface (62b) of the rear plate stack (60). The amount of protrusion of the rear relay portion (64) from the second right side surface (62b) is smaller than the amount of protrusion of the rear connection portion (63) from the second left side surface (62a). The rear relay portion (64) is joined to an end of the second internal pipe (39) by brazing.

[0080] The gas end portion (65) is a circular pipe. The gas end portion (65) is provided on the fifth rear plate (625) and disposed on the second right side surface (62b) of the rear main body portion (62). The amount of protrusion of the gas end portion (65) from the second right side surface (62b) is the same as the amount of protrusion of the gas end portion (65) from the second right side surface (62b) of the rear relay portion (64). The gas end portion (65) is joined to an end portion of the gas relay pipe (12a) by brazing.

[0081] The rear relay part (64) and the gas end part (65) are molded seamlessly and integrally with the fifth rear plate (625). More specifically, the rear relay part (64), the gas end part (65), and the fifth rear plate (625) are configured from a single member. The rear relay part (64) and the gas end part (65) are molded integrally with the fifth rear plate (625) by burring the fifth rear plate (625). The rear relay part (64) and the gas end part (65) may be molded integrally with the fifth rear plate (625) by casting or sintering metal powder using a 3D printer.

[0082] (5) Method of connecting the joint to the heat transfer tube A method of connecting the front connection portion (53) and the heat transfer tube (42) will be described.

[0083] First, as shown in Fig. 10, the front plate stack (50) is disposed on the lower side, and the front heat exchange section (40A) is disposed on the upper side. The front plate stack (50) is in a state in which the plates (521, 522, 523, 524, 525) are joined by brazing. The front heat exchange section (40A) is in a state in which the heat transfer tubes (42) penetrate the surface-treated fins (41).

[0084] Next, the brazing material 70 is placed on the annular surface 72 of the front connection portion 53. The brazing material 70 before being melted is ring-shaped. The outer diameter of the brazing material 70 is smaller than the outer diameter of the annular surface 72.

[0085] 11, the heat transfer tube (42) is inserted into the front connection portion (53). The heat transfer tube (42) is inserted 2 mm or more into the front connection portion (53). A gap is provided between the outer circumferential surface of the heat transfer tube (42) and the inner circumferential surface of the front connection portion (53).

[0086] 12, the brazing material (70) is melted by a burner to join the front connection portion (53) and the heat transfer tube (42). After the molten brazing material (70) is received by the brazing material receiving portion (73), it flows into the gap between the front connection portion (53) and the heat transfer tube (42) and solidifies. The brazing material (70) that does not flow into the gap between the front connection portion (53) and the heat transfer tube (42) is received by the brazing material receiving portion (73) and solidifies at the brazing material receiving portion (73).

[0087] The method of connecting the rear connection portion (63) to the heat transfer tube (42) is the same as the method of connecting the front connection portion (53) to the heat transfer tube (42).

[0088] (6) Driving behavior The air conditioner (10) performs a cooling operation, a heating operation, and a dehumidifying operation.

[0089] (6-1) Cooling operation In the cooling operation, the controller of the air conditioner (10) operates the compressor (21), the outdoor fan (25), and the indoor fan (32), sets the four-way switching valve (24) to the first state (the state shown by the solid line in FIG. 1), appropriately adjusts the opening degree of the outdoor expansion valve (23), and fully opens the indoor expansion valve (37).

[0090] In the cooling operation, the refrigerant circuit (11) performs a refrigeration cycle in which the outdoor heat exchanger (22) functions as a condenser (heat radiator) and the indoor heat exchanger (40) functions as an evaporator.

[0091] The indoor unit (30) draws indoor air from the indoor space (I) into the air passage (P) through the inlet (33). The air in the air passage (P) is cooled by the indoor heat exchanger (40). The cooled air is supplied to the indoor space (I) through the air outlet (34).

[0092] (6-2) Heating operation In the heating operation, the controller of the air conditioner (10) operates the compressor (21), the outdoor fan (25), and the indoor fan (32), sets the four-way switching valve (24) to the second state (the state shown by the dashed line in FIG. 1), adjusts the opening degree of the outdoor expansion valve (23) to a predetermined opening degree, and fully opens the indoor expansion valve (37).

[0093] In the heating operation, the refrigerant circuit (11) performs a refrigeration cycle in which the indoor heat exchanger (40) functions as a condenser (heat radiator) and the outdoor heat exchanger (22) functions as an evaporator.

[0094] The indoor unit (30) draws indoor air from the indoor space (I) into the air passage (P) through the inlet (33). The air in the air passage (P) is heated by the indoor heat exchanger (40). The heated air is supplied to the indoor space (I) through the air outlet (34).

[0095] (6-3) Dehumidification operation In the dehumidification operation, a controller of the air conditioner (10) operates the compressor (21), the outdoor fan (25), and the indoor fan (32), sets the four-way switching valve (24) to the first state (the state shown by the solid line in FIG. 1), and appropriately adjusts the openings of the outdoor expansion valve (23) and the indoor expansion valve (37).

[0096] During dehumidification operation, the refrigerant circuit (11) performs a refrigeration cycle in which the outdoor heat exchanger (22) and the front heat exchange section (40A) of the indoor heat exchanger (40) function as a condenser (heat radiator), and the rear heat exchange section (40B) of the indoor heat exchanger (40) functions as an evaporator.

[0097] The indoor unit (30) draws room air from the indoor space (I) into the air passage (P) through the inlet (33). The rear heat exchange section (40B) cools the air in the air passage (P) to a temperature equal to or lower than the dew point temperature. The front heat exchange section (40A) heats the air in the air passage (P). The air that has passed through both sections mixes in the air passage (P) to become low-humidity air. The air dehumidified in this manner is supplied to the indoor space (I) through the air outlet (34).

[0098] (7) Effects of the First Embodiment In the first embodiment, the fins (41) are subjected to a surface treatment. If the front connection portion (53) and the heat transfer tube (42) are brazed in a heat treatment furnace, the effect of the surface treatment applied to the fins (41) may be deteriorated. In order to braze the front connection portion (53) and the heat transfer tube (42) while maintaining the effect of the surface treatment of the fins (41), it is necessary to locally braze the front connection portion (53) and the heat transfer tube (42). When brazing is performed with a burner, the upper side is likely to become hotter than the lower side due to thermal convection. If the front plate stack (50) is placed on the upper side and the front heat exchange portion (40A) is placed on the lower side, the front plates (521 to 525) may be heated by the heat of the burner, and the brazing material joining the front plates may be remelted.

[0099] In contrast, in the first embodiment, when the front connection portion (53) and the heat transfer tube (42) are brazed together, the front heat exchange portion (40A) is positioned on the upper side and the front plate stack (50) is positioned on the lower side, thereby suppressing re-melting of the brazing material of the front plate stack (50).

[0100] In the first embodiment, the front connection part (53) has an annular surface (72) that is continuous with the joint surface (71) between the front connection part (53) and the heat transfer tube (42) and is annular when viewed from the front heat exchange part (40A) side in the axial direction of the heat transfer tube (42), and the annular surface (72) has a brazing material receiving part (73). When the front connection part (53) and the heat transfer tube (42) are brazed in a position in which the front heat exchange part (40A) is arranged on the upper side and the front plate stack (50) is arranged on the lower side, the brazing material receiving part (73) can receive the molten brazing material (70). The brazing material receiving part (73) can prevent the brazing material (70) from dripping downward, so that the connection accuracy between the front connection part (53) and the heat transfer tube (42) can be maintained at a high level.

[0101] In the first embodiment, the width between the inner edge and the outer edge of the annular surface (72) is 0.6-1.5 mm, so that the brazing material receiving portion (73) can be made as wide as possible, and the brazing material receiving portion (73) can receive as much of the brazing material (70) as possible. This prevents the brazing material (70) from dripping, and maintains a high level of connection accuracy between the front connection portion (53) and the heat transfer tube (42).

[0102] In the first embodiment, since the insertion distance between the front connection part (53) and the heat transfer tube (42) is 2 mm or more, it is possible to flow as much brazing material (70) as possible between the front connection part (53) and the heat transfer tube (42), and to reduce the amount of brazing material (70) received by the brazing material receiver (73). This prevents the brazing material (70) from dripping, and maintains high connection accuracy between the front connection part (53) and the heat transfer tube (42).

[0103] In the first embodiment, since the heat transfer tube (42) is inserted inside the front connection portion (53), the brazing material (70) easily flows between the front connection portion (53) and the heat transfer tube (42), and the amount of the brazing material (70) received by the brazing material receiver (73) can be reduced. This suppresses dripping of the brazing material (70) and maintains high connection accuracy between the front connection portion (53) and the heat transfer tube (42).

[0104] Second Embodiment The embodiments of the present disclosure will be described in detail with reference to the drawings. In the following description, the same reference numerals are used to designate parts common to the first embodiment, and detailed description thereof will be omitted.

[0105] (8) Connection As shown in Fig. 13, in the second embodiment, the front connection part (253) of the front plate stack (250) is a circular tube. The front connection part (253) has a flare part (253a) that is flared at an end part on the front heat exchange part (40A) side. The flare part (253a) has a tapered part (253b) at a tip part, the diameter of which increases toward the tip side. The inner diameter of the front connection part (253) excluding the flare part (253a) is smaller than the outer diameter of the heat transfer tube (42). The length of the flare part (253a) is longer than the insertion distance between the front connection part (253) and the heat transfer tube (42), and is, for example, 2 mm or more.

[0106] The flare portion (253a) is located outside the corresponding heat transfer tube (42). In other words, the heat transfer tube (42) is inserted inside the flare portion (253a). The insertion distance between the front connection portion (253) and the heat transfer tube (42) is 2 mm or more. The front connection portion (253) is joined to the corresponding heat transfer tube (42) at the position of the flare portion (253a) by burner brazing. The inner peripheral surface of the flare portion (253a) has a joint surface (271) which is a joint portion with the heat transfer tube (42). The outer peripheral surface of the heat transfer tube (42) and the joint surface (271) are spaced apart from each other, and the brazing material (270) is located between the outer peripheral surface of the heat transfer tube (42) and the joint surface (271). The material of the brazing material (270) is the same as that of the first embodiment described above.

[0107] As shown in FIG. 14, the inner peripheral surface of the tapered portion (253b) is an annular surface (272) that is annular when viewed from the front heat exchange portion (40A) side in the axial direction of the heat transfer tube (42). The annular surface (272) is continuous with the joint surface (271). The annular surface (272) surrounds the heat transfer tube (42) from the outside. The width between the inner end and the outer end of the annular surface (272) is the same as or larger than the thickness of the front connection portion (253). The width between the inner end and the outer end of the annular surface (272) is, for example, 0.6 mm to 1.5 mm.

[0108] At least a portion of the annular surface (272) is a braze receiving portion (273) that receives the molten braze material (270).

[0109] Although not shown, the rear connection portion is also formed of a circular tube and has a flared portion, similar to the front connection portion (253). The flared portion also has a tapered portion. The inner circumferential surface of the tapered portion is an annular surface when viewed from the rear heat exchange portion (40B) side in the axial direction of the heat transfer tube (42), and at least a part of the annular surface is a brazing material receiving portion.

[0110] (9) Effects of the Second Embodiment In the second embodiment, the front connection part (253) is a circular tube and has a flare part (253a) at the end part on the front heat exchange part (40A) side, and the annular surface (272) is formed at the end part of the flare part (253a). This allows the brazing material receiving part (273) of the annular surface (272) to be formed wide, and dripping of the molten brazing material (270) can be suppressed. This allows the connection precision between the front connection part (253) and the heat transfer tube (42) to be maintained at a high level.

[0111] In the second embodiment, the tip of the flare portion (253a) is a tapered portion (253b) whose diameter increases toward the tip, and the annular surface (272) is the inner circumferential surface of the tapered portion (253b). When the brazing material (270) is placed on the annular surface (272) and melted in a state in which the front plate assembly (250) is disposed on the lower side and the front heat exchange section (40A) is disposed on the upper side, the brazing material (270) tends to flow downward along the annular surface. Since the molten brazing material (270) is less likely to leak out of the front connection portion (253), the connection accuracy between the front connection portion (253) and the heat transfer tube (42) can be improved.

[0112] Third embodiment A third embodiment of the present disclosure will be described in detail with reference to the drawings. In the following description, the same reference numerals will be used to designate parts common to the first to third embodiments, and detailed description thereof will be omitted.

[0113] (10) Connection The front plate stack (350) according to the third embodiment has a different configuration from the front plate stacks (350) according to the first to third embodiments. Specifically, in the front plate stack (350), the front connection portion (353) is not formed of a circular tube, but is formed of a round hole penetrating the first front plate (3521). The thickness of the first front plate (3521) is the same as or thicker than that of the intermediate plate. The inner diameter of the front connection portion (353) is slightly larger than the outer diameter of the heat transfer tube (42).

[0114] The inner peripheral surface of the front connection portion (353) is located outside the corresponding heat transfer tube (42). In other words, the heat transfer tube (42) is inserted inside the front connection portion (353). The insertion distance between the front connection portion (353) and the heat transfer tube (42) is 2 mm or more. The front connection portion (353) is joined to the corresponding heat transfer tube (42) by burner brazing. The inner peripheral surface of the front connection portion (353) has a joint surface (371) which is a joint portion with the heat transfer tube (42). The outer peripheral surface of the heat transfer tube (42) and the joint surface (371) are spaced apart from each other, and the brazing material (370) is located between the outer peripheral surface of the heat transfer tube (42) and the joint surface (371). The material of the brazing material (370) is the same as that of the first embodiment described above.

[0115] As shown in FIGS. 15 and 16, a portion of the front connection portion (353) on the front heat exchange portion (40A) side forms a step portion (353a). The step portion (353a) is a portion having a larger diameter than other portions of the front connection portion (353). A bottom surface of the step portion (353a) is an annular surface (372) that is annular when viewed from the front heat exchange portion (40A) side in the axial direction of the heat transfer tube (42). The annular surface (372) is continuous with the joining surface (371). The annular surface (372) surrounds the heat transfer tube (42) from the outside. The width between the inner edge and the outer edge of the annular surface (372) is, for example, 0.6 mm to 1.5 mm. The height of the step portion (353a) is set to a height such that the molten and solidified brazing material (370) does not protrude from the first left side surface (352c).

[0116] The annular surface (372) is a braze receiving portion (373) that receives the molten braze material (370).

[0117] Although not shown, the rear connection portion is also formed of a round hole penetrating the first rear plate, and has a step on the rear heat exchange portion (40B) side, similar to the front connection portion (353). The step is an annular surface that has a circular ring shape when viewed from the rear heat exchange portion (40B) side in the axial direction of the heat transfer tube (42), and the annular surface is a brazing material receiving portion.

[0118] (11) Effects of the Third Embodiment In the third embodiment, the front connection part (353) has a step part (353a) on the front heat exchange part (40A) side, and the brazing material receiving part (373) is the bottom surface of the step part (353a). The step part (353a) makes it difficult for the molten brazing material (370) to leak from the front connection part (353), and makes it easier for the brazing material receiving part (373) to receive the molten brazing material (370). In addition, the brazing material (370) easily flows into the gap between the front connection part (353) and the heat transfer tube. It is possible to maintain high connection accuracy between the front connection part (353) and the heat transfer tube (42).

[0119] Fourth embodiment A fourth embodiment of the present disclosure will be described in detail with reference to the drawings. In the following description, the same reference numerals will be used to designate parts common to the first to fourth embodiments, and detailed description thereof will be omitted.

[0120] (12) Connection As shown in FIGS. 17 to 19, in the fourth embodiment, the front connection portion (453) of the front plate stack (450) is a circular tube. The front connection portion (453) has a tapered portion (453a) at an end portion on the front heat exchange portion (40A) side, the tapered portion (453a) having a smaller diameter than the other portion. A base end portion of the tapered portion (453a) is a step portion (453b). The outer diameter of the tapered portion (453a) is smaller than the inner diameter of the heat transfer tube (42). The outer diameter of the portion of the front connection portion (453) excluding the tapered portion (453a) is larger than the inner diameter of the heat transfer tube (42). The length of the tapered portion (453a) is longer than the insertion distance between the front connection portion (453) and the heat transfer tube (42), and is, for example, 2 mm or more.

[0121] The narrowed portion (453a) is inserted into the corresponding heat transfer tube (42). The insertion distance between the front connection portion (453) and the heat transfer tube (42) is 2 mm or more. The front connection portion (453) is joined to the corresponding heat transfer tube (42) at the position of the narrowed portion (453a) by burner brazing. The outer circumferential surface of the narrowed portion (453a) has a joint surface (471) which is a joint portion with the heat transfer tube (42). The inner circumferential surface of the heat transfer tube (42) and the joint surface (471) are spaced apart, and the brazing material (470) is located between the inner circumferential surface of the heat transfer tube (42) and the joint surface (271). The material of the brazing material (470) is the same as that of the first embodiment described above.

[0122] As shown in FIG. 18 , the surface of the step portion (453b) is an annular surface (472) that is annular when viewed from the front heat exchange portion (40A) side in the axial direction of the heat transfer tube (42). The annular surface (472) is continuous with the joint surface (471). The width between the inner edge and the outer edge of the annular surface (472) is greater than the thickness of the heat transfer tube (42). The width between the inner edge and the outer edge of the annular surface (472) is equal to or greater than the thickness of the front connection portion (453). The width between the inner edge and the outer edge of the annular surface (472) is, for example, 0.6 mm to 1.5 mm. A part of the annular surface (472) surrounds the heat transfer tube (42) from the outside.

[0123] At least a part of the annular surface (472) is a braze receiving portion (473) that receives the molten braze material (470). The braze receiving portion (473) overlaps with the heat transfer tube (42) when viewed from the front heat exchange portion (40A) side in the axial direction of the heat transfer tube (42).

[0124] Although not shown, the rear connection portion is also formed of a circular tube and has a tapered portion, similar to the front connection portion (453). The flare portion has a step. The surface of the step is an annular surface when viewed from the rear heat exchange portion (40B) side in the axial direction of the heat transfer tube (42), and at least a part of the annular surface is a brazing material receiving portion.

[0125] (13) Method of connecting the joint to the heat transfer tube In the fourth embodiment, when joining the front connection portion (453) and the heat transfer tube (42), the front plate stack (50) is placed on the lower side and the front heat exchange portion (40A) is placed on the upper side, and a brazing material (470) is placed on the annular surface (472) of the front connection portion (453).

[0126] Next, as shown in FIG. 19, the front heat exchange section (40A) is moved so that the front connection section (453) is inserted inside the heat transfer tube (42).

[0127] Thereafter, the heat transfer tube (42) and the front connection portion (453) are heated with a burner to melt the brazing material (470). The molten brazing material (470) is stored in the brazing material receiving portion (473) and is sucked up into the gap between the front connection portion (53) and the heat transfer tube (42) by capillary action and solidifies. The brazing material (470) that drips down without being sucked up is received by the brazing material receiving portion (473) and then solidifies.

[0128] The method of connecting the rear connection portion to the heat transfer tube (42) is the same as the method of connecting the front connection portion (453) to the heat transfer tube (42).

[0129] (14) Effects of the fourth embodiment In the fourth embodiment, since the front connection portion (453) is inserted inside the heat transfer tube (42), when the front connection portion (453) and the heat transfer tube (42) are brazed together in a position in which the indoor heat exchanger (40) is arranged on the upper side and the front plate assembly (450) is arranged on the lower side, there is a high possibility that the brazing material (470) will drip downward. In response to this, by providing the front connection portion (453) with the narrowed portion (453a), it is possible to form an annular surface (472) as wide as possible in a portion other than the narrowed portion (453a). This allows the brazing material receiving portion (473) to be as wide as possible, thereby suppressing the dripping of the brazing material (470) and maintaining a high connection accuracy between the front connection portion (453) and the heat transfer tube (42).

[0130] In addition, when the front connection portion (453) and the heat transfer tube (42) are brazed together, the heat transfer tube (42) is heated, so that the brazing material (470) melts first from the heat transfer tube (42), and the molten brazing material (470) is easily sucked up into the gap between the front connection portion (53) and the heat transfer tube (42). This prevents the brazing material (470) from dripping, and the connection accuracy between the front connection portion (453) and the heat transfer tube (42) can be maintained at a high level.

[0131] (15) Other embodiments The indoor heat exchanger (40) does not have to be of a fin-and-tube type and may be of, for example, a corrugated type in which corrugated fins are arranged between adjacent heat transfer tubes.

[0132] The heat exchanger body (B) may have one heat exchange section, without including the front heat exchange section (40A) and the rear heat exchange section (40B). In this case, the first internal pipe (38), the second internal pipe (39), and the indoor expansion valve (37) are omitted.

[0133] The front connection portion (53, 253, 353, 453) and the rear connection portion may have different configurations. For example, only the front connection portion (253) may have a flare portion (253a), and the rear connection portion may have no flare portion.

[0134] The toroidal surface (72, 272, 372, 472) does not have to be a circular torus. The toroidal surface (72, 272, 372, 472) may be an elliptical torus or a rectangular torus.

[0135] When the front connection portion (253) has a flared portion (253a) as in the second embodiment, or when the front connection portion (453) has a narrowed portion (453a) as in the fourth embodiment, the thickness of the front connection portion (253, 453) may be less than 0.6 mm.

[0136] There is no particular limitation on the order of the step of arranging the brazing material (70, 270, 370, 470) and the step of inserting the heat transfer tube (42) into the front connection portion (53, 253, 353, 453). The brazing material (70, 270, 370, 470) may be arranged on the annular surface (72, 272, 372, 472) after inserting the heat transfer tube (42) into the front connection portion (53, 253, 353, 453).

[0137] Although the embodiments and modifications have been described above, it will be understood that various modifications of form and details are possible without departing from the spirit and scope of the claims. Furthermore, the above embodiments, modifications, and other embodiments may be appropriately combined or substituted as long as the functions of the subject of the present disclosure are not impaired.

[0138] The descriptions "first," "second," "third," etc. mentioned above are used to distinguish the words to which these descriptions are attached, and do not limit the number or order of the words. [Industrial Applicability]

[0139] INDUSTRIAL APPLICABILITY As described above, the present disclosure is useful for an indoor heat exchanger, an air conditioner indoor unit, and a method for manufacturing an indoor heat exchanger. [Explanation of symbols]

[0140] 31 Casing 40 Indoor heat exchanger 40A Front heat exchanger 41 Finn 42 Heat transfer tube 50 Front plate stack 51 Coolant flow path 53 Front connection part 70 Brazing material 71 Joint surface 72 Circular Surface 73 Brazing piece 250 Front plate stack 253 Front connection part 253a Flare section 270 Brazing material 271 Joint surface 272 Circular Surface 273 Brazing piece 350 Front plate stack 353 Front connection part 370 Brazing material 371 Joint surface 372 Annular Surface 373 Brazing piece 450 Front Plate Stack 453 Front connection part 453a Squeezing section 470 Brazing material 471 Joint surface 472 Annular Surface 473 Brazing piece

Claims

1. a heat exchange section (40A) having fins (41) and a heat transfer tube (42); a plate stack (50, 250, 350, 450) having a refrigerant flow path (51) in communication with the heat transfer tube (42) and a connection portion (53, 253, 353, 453) in communication with the refrigerant flow path (51) and to which the heat transfer tube (42) is connected, the connection portion (53, 253, 353, 453) has an annular surface (72, 272, 372, 472) that is continuous with a joint surface (71, 271, 371, 471) between the connection portion (53, 253, 353, 453) and the heat transfer tube (42) and has an annular shape as viewed from the heat exchange portion (40A) side in the axial direction of the heat transfer tube (42), The annular surface (72, 272, 372, 472) is an indoor heat exchanger having a brazing material receiving portion (73, 273, 373, 473) that receives a brazing material (70, 270, 370, 470).

2. 2. The heat exchanger according to claim 1, An indoor heat exchanger, wherein the width between the inner and outer edges of the annular surface (72, 272, 372, 472) is between 0.6 mm and 1.5 mm.

3. 3. The heat exchanger according to claim 2, An indoor heat exchanger, wherein an insertion distance between the connection portion (53, 253, 353, 453) and the heat transfer tube (42) is 2 mm or more.

4. In the heat exchanger according to claim 2 or 3, The heat transfer tube (42) is an indoor heat exchanger that is inserted into the inside of the connection portion (53, 253).

5. In the heat exchanger according to claim 2 or 3, The connection part (253) is a connecting pipe and is an indoor heat exchanger having a flare part (253a) at an end part on the heat exchange part (40A) side.

6. In the heat exchanger according to claim 2 or 3, The connection part (453) is a connecting pipe and has a throttle part (453a) at an end part on the heat exchange part (40A) side. The throttle portion (453a) is an indoor heat exchanger that is inserted inside the heat transfer tube (42).

7. An indoor heat exchanger according to any one of claims 1 to 3; and a casing (31) that houses the indoor heat exchanger.

8. A method for manufacturing an indoor heat exchanger, comprising the steps of: The indoor heat exchanger is a heat exchange section (40A) having fins (41) and a heat transfer tube (42); a plate stack (50, 250, 350, 450) having a refrigerant flow path (51) in communication with the heat transfer tube (42) and a connection portion (53, 253, 353, 453) in communication with the refrigerant flow path (51) and to which the heat transfer tube (42) is connected, the connection portion (53, 253, 353, 453) has an annular surface (72, 272, 372, 472) that is continuous with a joint surface (71, 271, 371, 471) between the connection portion (53, 253, 353, 453) and the heat transfer tube (42) and has an annular shape as viewed from the heat exchange portion (40A) side in the axial direction of the heat transfer tube (42), a first step of arranging the plate stack (50, 250, 350, 450) on a lower side and the heat exchange section (40A) on an upper side; a second step of disposing a brazing material (70, 270, 370, 470) on the annular surface (72, 272, 372, 472); a third step of inserting one of the heat transfer tube (42) and the connection portion (53, 253, 353, 453) into the other of the heat transfer tube (42) and the connection portion (53, 253, 353, 453); a fourth step of melting the brazing material (70, 270, 370, 470) with a burner to join the connection portion (53, 253, 353, 453) and the heat transfer tube (42).

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