Indoor heat exchanger and indoor air conditioning unit, and method for manufacturing an 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 Art

[0002] Patent Document 1 discloses a refrigerant diverter used in an air conditioner. The refrigerant diverter 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 connection pipe is connected. It is disclosed that brazing of the underplate and the overplate and brazing of the connection pipe and the burring hole are simultaneously performed in a heat treatment furnace. In Patent Document 1, the connection pipe is connected to the heat transfer pipe of the heat exchanger.

[0003] Patent Document 2 discloses a heat exchanger of an air-conditioning indoor unit. The heat exchanger includes a heat exchanger body having fins and heat transfer pipes, and a refrigerant distributor that distributes and supplies refrigerant to a plurality of predetermined flow path portions in the heat exchanger body. The refrigerant distributor is composed of a plurality of plate-like members that are polymerized with each other and include a plate-like distribution member. The plurality of plate-like members are brazed and joined using a continuous heat treatment furnace. One of the plate-like members has a burring hole, and the burring hole is connected to the heat transfer pipe.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

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

[0006] As described in Patent Documents 1 and 2, plate stacks and heat transfer tubes in a heat exchange section are generally connected by brazing. Brazing of the plate stack and heat transfer tubes can be performed using a heat treatment furnace, as described in Patent Document 1. When brazing the plate stack and heat transfer tubes using a heat treatment furnace, the heat exchange section including the fins and the plate stack are placed in 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] To minimize the impact on the surface treatment of the fins, it is conceivable to braze the plate stack and the heat transfer tubes using torch brazing. When performing torch brazing, the plate stack, which is relatively smaller in size, is usually placed on top and the heat exchanger on the bottom. However, when using torch brazing, the upper side tends to become hotter than the lower side due to the effect of thermal convection, so there is a risk that the plates will also be heated by the heat of the torch. If the plates are heated, there is a risk that the brazing material used to join the plates together will remelt.

[0008] To address this issue, one possible approach is to braze the heat exchanger with the plate stack positioned on top and the plate stack on the bottom. However, there is a risk that the brazing material may not flow between the connection point and the heat transfer tube, but instead drip downwards, potentially degrading the connection accuracy.

[0009] The purpose of this disclosure is to suppress the remelting of the brazing material when connecting the connection part of the plate laminate to the heat transfer tube, while maintaining the connection accuracy between the connection part and the heat transfer tube. [Means for solving the problem]

[0010] The first embodiment relates to an indoor heat exchanger. The indoor heat exchanger comprises a heat exchange section (40A) having fins (41) and heat transfer tubes (42), a plate laminate (50,250,350,450) having a refrigerant flow path (51) communicating with the heat transfer tubes (42), and a connecting section (53,253,353,453) communicating with the refrigerant flow path (51) and to which the heat transfer tubes (42) are connected, wherein the connecting section (5 The joint surface (71,271,371,471) between the heat transfer tube (42) and the heat transfer tube (42) has an annular surface (72,272,372,472) that is continuous with the joint surface (71,271,371,471) and is an annular surface (72,272,372,472) when viewed from the heat exchange section (40A) side in the axial direction of the heat transfer tube (42), and the annular surface (72,272,372,472) has a brazing receiving portion (73,273,373,473) that receives the brazing material (70,270,370,470).

[0011] In the first embodiment, in order to suppress the remelting of the brazing material of the plate stack (50, 250, 350, 450), the heat exchange section (40A) is positioned on the upper side and the plate stack (50, 250, 350, 450) is positioned on the lower side. When brazing the connection section (53, 253, 353, 453) and the heat transfer tube (42) in this configuration, the brazing receiving section (73, 273, 373, 473) can receive the molten brazing material (70, 270, 370, 470). The brazing receiving section (73, 273, 373, 473) can suppress the dripping of the brazing material (70, 270, 370, 470) downwards, thereby maintaining a high level of connection accuracy between the connection section (53, 253, 353, 453) and the heat transfer tube (42).

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

[0013] In the second embodiment, the brazing receiving section (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 receiving section (73, 273, 373, 473) as much as possible. As a result, dripping of the brazing material (70, 270, 370, 470) is suppressed, and the connection accuracy between the connection section (53, 253, 353, 453) and the heat transfer tube (42) can be maintained at a high level.

[0014] In the third embodiment, in the first or second embodiment, the insertion distance between the connecting portion (53, 253, 353, 453) and the heat transfer tube (42) is 2 mm or more.

[0015] In the third embodiment, as much brazing material as possible can be flowed between the connection parts (53, 253, 453) and the heat transfer tubes (42), and the amount of brazing material (70, 270, 470) received by the brazing receiving parts (73, 273, 473) can be reduced. As a result, dripping of the brazing material (70, 270, 470) is suppressed, and the connection accuracy between the connection parts (53, 253, 453) and the heat transfer tubes (42) can be maintained at a high level.

[0016] In the fourth embodiment, in any one of the first to third embodiments, the heat transfer tube (42) is inserted inside the connection portion (53, 253).

[0017] In the fourth embodiment, the brazing material (70,270) flows more easily between the connection part (53,253) and the heat transfer tube (42), so the amount of brazing material (70,270) received by the brazing receiving part (73,273) can be reduced. As a result, dripping of the brazing material (70,270) is suppressed, and the connection accuracy between the connection part (53,253) and the heat transfer tube (42) can be maintained at a high level.

[0018] The fifth aspect is the fourth aspect, wherein the connecting portion (253) is a connecting pipe and has a flared portion (253a) at the end on the heat exchange portion (40A) side.

[0019] In the fifth embodiment, the flared portion (253a) makes the brazing receiving portion (273) as wide as possible, thereby suppressing dripping of the brazing material (270). This makes it possible to maintain a high level of connection accuracy between the connection portion (253) and the heat transfer tube (42).

[0020] The sixth embodiment is one of the first to third embodiments in which the connecting portion (453) is a connecting tube and has a constricted portion (453a) at the end on the heat exchange portion (40A) side, and the constricted portion (453a) is inserted inside the heat transfer tube (42).

[0021] In the sixth embodiment, by providing a constricted portion (453a) in the connecting portion (453), the widest possible annular surface (472) can be formed in the portion other than the constricted portion (453a). As a result, the brazing receiving portion (473) can be made as wide as possible, which suppresses dripping of the brazing material (470) and maintains a high level of connection accuracy between the connecting portion (453) and the heat transfer tube (42).

[0022] The seventh embodiment relates to an indoor air conditioner. The indoor air conditioner comprises an indoor heat exchanger according to any one of the first to sixth embodiments, and a casing (31) that houses the indoor heat exchanger.

[0023] Aspect 8 is directed to a method of manufacturing an indoor heat exchanger. The indoor heat exchanger includes a heat exchange section (40A) having fins (41) and heat transfer tubes (42), a refrigerant flow path (51) communicating with the heat transfer tubes (42), and a plate laminate (50, 250, 350, 450) having a connection section (53, 253, 353, 453) that communicates with the refrigerant flow path (51) and to which the heat transfer tubes (42) are connected. The connection section (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 section (53, 253, 353, 453) and the heat transfer tubes (42) and is annular when viewed from the heat exchange section (40A) side in the axial direction of the heat transfer tubes (42). The method of manufacturing an indoor heat exchanger includes a first step of disposing the plate laminate (50, 250, 350, 450) on the lower side and disposing the heat exchange section (40A) on the 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 tubes (42) and the connection section (53, 253, 353, 453) into the other of the heat transfer tubes (42) and the connection section (53, 253, 353, 453), and a fourth step of melting the brazing material (70, 270, 370, 470) by a burner to join the connection section (53, 253, 353, 453) and the heat transfer tubes (42).

[0024] In Aspect 8, even if the plate laminate (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 tubes (42) are brazed with a burner, the molten brazing material (70, 270, 370, 470) can be received by the annular surface (72, 272, 372, 472). Thereby, dripping of the brazing material (70, 270, 370, 470) is suppressed, and the connection accuracy between the connection section (53, 253, 353, 453) and the heat transfer tubes (42) can be maintained in a high state.

Brief Description of the Drawings

[0025] [Figure 1]FIG. 1 is a piping system diagram of an air conditioner having an indoor heat exchanger according to Embodiment 1. [Figure 2] FIG. 2 is a front view of the air conditioning indoor unit. [Figure 3] FIG. 3 is a cross-sectional view taken along line II-II of the air conditioning indoor unit. [Figure 4] FIG. 4 is a front view showing the internal structure of the air conditioning indoor unit. [Figure 5] FIG. 5 is a plan view showing the heat exchange unit. [Figure 6] FIG. 6 is a view of the plate laminate seen from the left side. [Figure 7] FIG. 7 is a cross-sectional view illustrating the refrigerant flow path of the plate laminate. [Figure 8] FIG. 8 is a cross-sectional view showing the connection state between the heat transfer tube and the front connection part. [Figure 9] FIG. 9 is a cross-sectional view corresponding to line IX-IX of FIG. 8. [Figure 10] FIG. 10 is a cross-sectional view showing the process of connecting the heat transfer tube and the front connection part, showing the state before the heat transfer tube is inserted into the front connection part. [Figure 11] FIG. 11 is a cross-sectional view showing the process of connecting the heat transfer tube and the front connection part, showing the state where the heat transfer tube is inserted into the front connection part. [Figure 12] FIG. 12 is a cross-sectional view showing the process of connecting the heat transfer tube and the front connection part, showing the state where the heat transfer tube and the front connection part are brazed. [Figure 13] FIG. 13 is a cross-sectional view showing the connection state between the heat transfer tube and the front connection part in the indoor heat exchanger according to Embodiment 2. [Figure 14] FIG. 14 is a cross-sectional view corresponding to line XIV-XIV of the figure. [Figure 15] FIG. 15 is a cross-sectional view showing the connection state between the heat transfer tube and the front connection part in the indoor heat exchanger according to Embodiment 3. [Figure 16] FIG. 16 is a cross-sectional view corresponding to line XVI-XVI of FIG. 14. [Figure 17]Figure 17 is a cross-sectional view showing the connection state between the heat transfer tube and the front connection part in an indoor heat exchanger according to Embodiment 4. [Figure 18] Figure 18 is a cross-sectional view corresponding to line XVIII-XVIII in Figure 17. [Figure 19] Figure 19 is a cross-sectional view showing the state in which the heat transfer tubes and the front connection part are brazed with a burner in an indoor heat exchanger according to Embodiment 4. [Modes for carrying out the invention]

[0026] The embodiments of this disclosure will be described in detail below with reference to the drawings. However, this disclosure is not limited to the embodiments shown below, and various modifications are possible without departing from the technical idea of ​​this disclosure. Since the drawings are for conceptual illustration of this disclosure, dimensions, ratios, or numbers may be exaggerated or simplified as necessary for ease of understanding.

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

[0028] As shown in Figure 1, the air conditioning system (10) is an example of a refrigeration cycle system equipped with a refrigerant circuit (11). The refrigerant circuit (11) is filled with refrigerant. The refrigerant circuit (11) performs a refrigeration cycle by circulating the refrigerant.

[0029] The air conditioning system (10) comprises an outdoor unit (20), an indoor unit (30), a first connecting pipe (12), and a second connecting pipe (13). The air conditioning system (10) is a paired 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. The outdoor unit (20) 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 an oscillating piston type, rotary type, or scroll type. The outdoor heat exchanger (22) exchanges heat between the refrigerant and the 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 (shown by the solid line in Figure 1) and a second state (shown by the dashed line in Figure 1). In the first state, the four-way switching valve (24) connects the discharge part of the compressor (21) to the gas end of the outdoor heat exchanger (22), and also connects the suction part of the compressor (21) to the first connecting pipe (12). The four-way switching valve (24) in the second state connects the discharge section of the compressor (21) to the first connecting pipe (12), and also connects the suction section of the compressor (21) to 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), an indoor heat exchanger (40) housed in the casing (31), an indoor fan (32), and an indoor expansion valve (37).

[0033] (2) Indoor unit of the air conditioner Details of the indoor unit (30), which is an indoor air conditioner, will be explained with reference to Figures 2 to 4. The indoor unit (30) of this embodiment 1 is a wall-mounted type installed on the wall of the indoor space (I). The terms "up," "down," "right," "left," "front," and "rear" described below correspond to the directions of the arrows shown in Figures 2 and 3, and the left and right directions are based on the view of the indoor casing (31) from the front.

[0034] (2-1) Casing As shown in Figures 2 and 3, the casing (31) is formed in a horizontally elongated box shape. The casing (31) has a front plate (31a), a rear plate (31b), a top plate (31c), a bottom 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 top plate (31c) is formed on the upper side of the casing (31) and constitutes the upper surface of the casing (31). The bottom 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 outlet port (34) is formed in the lower plate (31d). Inside the casing (31), an air passage (P) is formed from the intake port (33) to the outlet port (34). The intake port (33) extends in the longitudinal direction of the casing (31). The intake port (33) is an opening for drawing air from the indoor space (I) into the air passage (P). An outlet port (34) is formed in the lower plate (31d). The outlet port (34) extends in the longitudinal direction of the casing (31). The outlet 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) is equipped with a filter (35). The filter (35) is located behind the intake port (33) and upstream of the indoor heat exchanger (40). The filter (35) collects dust from the air sent from the intake port (33) to the indoor heat exchanger (40). The indoor unit (30) may also be equipped with a dust removal mechanism to remove the dust collected by the filter (35).

[0038] (2-3) Heat exchanger unit The heat exchanger unit (U) comprises one indoor heat exchanger (40) and one indoor expansion valve (37). The indoor heat exchanger (40) comprises one heat exchanger body (B) and two plate stacks (50, 60). The heat exchanger body (B) of the indoor heat exchanger (40) is positioned to traverse an 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 positioned in the air passage (P). The indoor fan (32) is positioned downstream of the indoor heat exchanger (40) in the air passage (P). The indoor fan (32) is a cross-flow fan. The fan rotor of the indoor fan (32) 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 the air blown out from the air outlet (34). The flap (36) adjusts the airflow direction in the vertical direction. The indoor unit (30) may have multiple flaps (36). The flaps (36) may also adjust the airflow direction in the horizontal direction.

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

[0042] (3-1) Indoor heat exchanger The indoor heat exchanger (40) shown in Figures 3 to 6 comprises a heat exchanger body (B) and plate stacks (50, 60) connected to the heat exchanger body (B). The indoor heat exchanger (40) is a fin-and-tube type 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 direction of the arrangement of the fins (41).

[0044] The direction of arrangement of the fins (41) corresponds to the longitudinal direction (in this case, left-right direction) of the casing (31). The fins (41) are rectangular plates with a long side and a short side. The thickness direction of the fins (41) corresponds to the direction of arrangement of the fins (41). Multiple fins (41) are arranged at predetermined intervals in their thickness direction. This interval constitutes an airflow channel. The material of the fins (41) is an aluminum alloy.

[0045] Multiple fins (41) are surface-treated to improve surface tension. The surface treatment is applied before the heat transfer tubes (42) are passed through the fins (41).

[0046] The heat transfer tubes (42) are straight tubes. The material of the multiple heat transfer tubes (42) is an aluminum alloy. The material of the heat transfer tubes (42) may also be a copper alloy. A flow path for the coolant is formed inside the heat transfer tubes (42). The multiple heat transfer tubes (42) extend parallel to each other so as to penetrate the fins (41). One end of the heat transfer tube (42), the right end, protrudes to the right of the fins (41). One end of the heat transfer tube is connected to the plate stack (50, 60). Of the other ends of the multiple heat transfer tubes (42), 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 as a single unit without any joints.

[0047] The indoor heat exchanger (40) of this embodiment 1 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 towards the front of the casing (31), and the rear heat exchange section (40B) is located towards the rear 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 vertical direction and the axial direction of the heat transfer tubes (42), i.e., in the front-to-back direction, with the indoor fan (32) in between.

[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 positioned closer to the indoor fan (32) in the front heat exchange section (40A). The outer shape of the front main heat exchange section (43) is formed in a V shape when viewed from the longitudinal direction of the heat transfer tubes (42). The tip of this V shape points forward.

[0050] The front main heat exchange section (43) is composed of a first front main heat exchange section (43a) that extends diagonally upward toward the rear and a second front main heat exchange section (43b) that extends diagonally downward toward the rear. The first front main heat exchange section (43a) is located at the top of the front main heat exchange section (43), and the second front main heat exchange section (43b) is located at the bottom 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), is in contact with the long side of the fin (41) of the second front main heat exchange section (43b) (more precisely, 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 formed as a single unit or as separate units.

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

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

[0055] The plate stack (50,60) is positioned to the right of the rightmost fin (41), parallel to the fin (41). The plate stack (50,60) is connected to one end of the heat transfer tube (42). As shown in Figure 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 positioned to overlap with the front heat exchange section (40A) in the axial direction of the heat transfer tube (42). The rear plate stack (60) is positioned to overlap with the rear heat exchange section (40B) in the axial direction of the heat transfer tube (42). The plate stacks (50, 60) have internal refrigerant flow paths (51, 61) that communicate with the heat transfer tubes (42). Details of the front plate stack (50) and the rear plate stack (60) will be described later.

[0056] (3-2) Indoor expansion valve, gas relay pipe, liquid relay pipe The indoor expansion valve (37) is an electronically controlled expansion valve with a variable opening. As shown in Figure 5, the indoor expansion valve (37) is located on the right side of the plate stack (50, 60). The indoor expansion valve (37) is connected to the front plate stack (50) via the first internal piping (38) and to the rear plate stack (60) via the second internal piping (39). The first internal piping (38) and the second internal piping (39) are examples of refrigerant piping 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).

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

[0058] (4) Plate stack Details of the plate stack (50,60) will be explained with reference to Figures 5 to 9.

[0059] (4-1) Front plate stack The front plate stack (50) includes a front main body (52) having a refrigerant flow path (51) inside, a plurality of front connection parts (53) that communicate 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 part (54) to which the first internal piping (38) is connected, and a liquid end part (55) that communicates with the second connecting piping (13) via a liquid relay pipe (13a).

[0060] (4-1-1) Front main body part As shown in Figure 5, the front main body (52) is a thick plate-shaped 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 tube (42). In the front plate stack (50), the first front plate (521), the second front plate (522), the third front plate (523), the fourth front plate (524), and the 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-shaped members with a common outer edge shape. In this embodiment 1, the material of each front plate is an aluminum alloy. The material of each front plate (521-525) is not limited to an aluminum alloy, but may be, for example, a copper alloy or stainless steel. The thickness of the first front plate (521) and the fifth front plate (525) is, for example, 1.5 mm. The thickness of the second front plate (522), the third front plate (523), and the fourth front plate (524) is, for example, 3.0 mm. Each front plate is 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 fewer, or six or more. Hereafter, when there is no need to distinguish between each front plate, they will simply be referred to as "front plates."

[0061] The front main body (52) has a first left side surface (52c), which is the side of the heat transfer tube (42) facing the front heat exchange section (40A) in the axial direction (in this case, the left side); a first right side surface (52d), which is the side opposite to the first left side surface (52c) in the axial direction; and a first circumferential surface (52e), which is the circumferential surface extending from the first left side surface (52c) to the first right side surface (52d). The first left side surface (52c) is the side of the first front plate (521) facing the front heat exchange section (40A). The first right side surface (52d) is the side of the fifth front plate (525) opposite to the fourth front plate (524). The first circumferential surface (52e) is the surface formed by the sides of each front plate (521, 522, 523, 524, 525). The first left side surface (52c) corresponds to a predetermined surface.

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

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

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

[0065] As shown in Figure 9, the end face of the front connection portion (53) on the front heat exchange portion (40A) side is an annular surface (72) when viewed from the front heat exchange portion (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 and outer edges of the annular surface (72) is equal to the wall thickness of the front connection portion (53). Specifically, the width between the inner and outer edges 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 receiving portion (73) that receives the molten brazing material (70).

[0067] The other end of the front connecting portion (53) is inserted into a through hole formed in the first front plate (521) and joined to the first front plate (521) by brazing. The front connecting portion (53) and the first front plate (521) may be integrally formed without seams, for example, by casting or sintering metal powder using a 3D printer.

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

[0069] The liquid end (55) is a cylindrical tube. The liquid end (55) is provided on the fifth front plate (525) and is positioned on the first right side (52d) of the front main body (52). The liquid end (55) is located in the second overlapping section (52b) of the fifth front plate (525). The amount of protrusion of the liquid end (55) from the first right side (52d) is the same as the amount of protrusion of the liquid end (55) from the first right side (52d) of the front intermediate section (54). The liquid end (55) is joined to the end of the liquid intermediate tube (13a) by brazing.

[0070] At 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 any other refrigerant flow paths (51). The refrigerant flow path (51) at the liquid end (55) communicates with the heat transfer tube (42) located at the lowest part of the second auxiliary heat exchange section (45).

[0071] The front intermediate section (54) and the liquid end section (55) are integrally molded with the fifth front plate (525) without any seams. More specifically, the front intermediate section (54), the liquid end section (55), and the fifth front plate (525) are made from a single component. The front intermediate section (54) and the liquid end section (55) are integrally molded with the fifth front plate (525) by burring the fifth front plate (525). Alternatively, the front intermediate section (54) and the liquid end section (55) may be integrally molded with the fifth front plate (525) by casting or sintering metal powder using a 3D printer.

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

[0073] (4-2-1) Rear main body The rear main body (62) is basically the same configuration as the front main body (52), except that the shape of the outer edge of the plate as viewed from the axial direction of the heat transfer tubes (42) and the internal refrigerant flow path (61) are different from those of the front main body (52). As shown in Figure 5, the rear main body (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), the first rear plate (621), the second rear plate (622), the third rear plate (623), the fourth rear plate (624), and the 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 this embodiment 1, the material of the rear plates is an aluminum alloy. The material of each rear plate (621-625) is not limited to an aluminum alloy, but may be, for example, a copper alloy or stainless steel. The thickness of the first rear plate (621) and the fifth rear plate (625) is, for example, 1.5 mm. The thickness of the second rear plate (622), the third rear plate (623), and the fourth rear plate (624) is, for example, 3.0 mm. The five rear plates are joined to each other by furnace brazing. Note that the number of rear plates is just an example, and the number of rear plates may be four or fewer, or six or more. The number of front plates and the number of rear plates may be different. Hereafter, when there is no need to distinguish between the rear plates, they will simply be referred to as "rear plates."

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

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

[0076] The thickness of the rear connection portion (63) is the same as 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 connector (63) is inserted inside the open end of the corresponding heat transfer tube (42) and joined to the heat transfer tube (42) by burner brazing. One end of the rear connector (63), like the front connector (53), has a joint surface which is the joint portion with the heat transfer tube (42). The edge of the rear connector (63) is continuous with the joint surface and has an annular surface when viewed from the rear heat exchange section (40B) side in the axial direction of the heat transfer tube (42). The annular surface has a brazing receiving portion that receives molten brazing material.

[0078] The other end of the rear connecting portion (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 connecting portion (63) and the first rear plate (621) may be integrally formed without seams, for example, by casting or sintering metal powder using a 3D printer.

[0079] (4-2-3) Rear relay section, gas end The rear intermediate section (64) is a circular pipe. As shown in Figure 6, the rear intermediate section (64) is provided on the fifth rear plate (625) and is positioned on the second right side (62b) of the rear main body (62). In other words, in the rear plate stack (60), the second internal piping (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 (62b) of the rear plate stack (60). The amount of protrusion of the rear intermediate section (64) from the second right side (62b) is smaller than the amount of protrusion of the rear connection section (63) from the second left side (62a). The rear intermediate section (64) is joined to the end of the second internal piping (39) by brazing.

[0080] The gas end (65) is a cylindrical tube. The gas end (65) is provided on the fifth rear plate (625) and is positioned on the second right side (62b) of the rear main body (62). The amount of protrusion of the gas end (65) from the second right side (62b) is the same as the amount of protrusion of the rear intermediate section (64) from the second right side (62b). The gas end (65) is joined to the end of the gas intermediate pipe (12a) by brazing.

[0081] The rear intermediate section (64) and the gas end (65) are seamlessly integrally molded with the fifth rear plate (625). More specifically, the rear intermediate section (64), the gas end (65), and the fifth rear plate (625) are composed of a single component. The rear intermediate section (64) and the gas end (65) are integrally molded with the fifth rear plate (625) by burring the fifth rear plate (625). Alternatively, the rear intermediate section (64) and the gas end (65) may be integrally molded with the fifth rear plate (625) by casting or sintering metal powder using a 3D printer.

[0082] (5) Method of connecting the connection part and the heat transfer tube The connection method for connecting the front connection part (53) and the heat transfer tube (42) will be explained below.

[0083] First, as shown in Figure 10, the front plate stack (50) is positioned on the lower side and the front heat exchange section (40A) is positioned on the upper side. The front plate stack (50) consists of plates (521, 522, 523, 524, 525) joined together by brazing. The front heat exchange section (40A) consists of surface-treated fins (41) through which heat transfer tubes (42) pass.

[0084] Next, the brazing material (70) is placed on the annular surface (72) of the front connecting portion (53). Before melting, the brazing material (70) is ring-shaped. The outer diameter of the brazing material (70) is smaller than the outer diameter of the annular surface (72).

[0085] Next, as shown in Figure 11, the heat transfer tube (42) is inserted into the front connection part (53). The heat transfer tube (42) is inserted into the front connection part (53) by at least 2 mm. There is a gap between the outer surface of the heat transfer tube (42) and the inner surface of the front connection part (53).

[0086] Next, as shown in Figure 12, the solder (70) is melted with a burner to join the front connector (53) and the heat transfer tube (42). The molten solder (70) is received by the solder receiving section (73) and then flows into the gap between the front connector (53) and the heat transfer tube (42) and solidifies. Any solder (70) that does not flow into the gap between the front connector (53) and the heat transfer tube (42) is received by the solder receiving section (73) and solidifies there.

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

[0088] (6) Operating The air conditioning system (10) performs cooling, heating, and dehumidifying operations.

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

[0090] During 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) via the intake port (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) from the outlet (34).

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

[0093] During heating operation, the refrigerant circuit (11) performs a refrigeration cycle in which the indoor heat exchanger (40) functions as a condenser (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) via the intake port (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) from the outlet (34).

[0095] (6-3) Dehumidification operation During dehumidification operation, the controller of the air conditioning unit (10) operates the compressor (21), outdoor fan (25), and indoor fan (32), sets the four-way switching valve (24) to the first state (shown by the solid line in Figure 1), and adjusts the opening of the outdoor expansion valve (23) and indoor expansion valve (37) as appropriate.

[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 condensers (radiators), and the rear heat exchange section (40B) of the indoor heat exchanger (40) functions as an evaporator.

[0097] The indoor unit (30) draws indoor air from the indoor space (I) into the air passage (P) via the intake port (33). The rear heat exchange unit (40B) cools the air in the air passage (P) to below the dew point temperature. The front heat exchange unit (40A) heats the air in the air passage (P). The air that has passed through both heat exchange units mixes in the air passage (P), resulting in air with low humidity. This dehumidified air is then supplied to the indoor space (I) from the outlet (34).

[0098] (7) Effects of Embodiment 1 In this embodiment 1, the fins (41) are surface-treated. If the front connection part (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 deteriorate. In order to braze the front connection part (53) and the heat transfer tube (42) while maintaining the effect of the surface treatment of the fins (41), it is necessary to braze locally with a burner. When brazing with a burner, the upper side tends to become hotter than the lower side due to thermal convection. If the front plate laminate (50) is on the upper side and the front heat exchange part (40A) is on the lower side, the heat from the burner may heat up to the front plates (521~525), and there is a risk that the brazing material joining the front plates will remelt.

[0099] In contrast, in this embodiment 1, when brazing the front connection part (53) and the heat transfer tube (42), the front heat exchange part (40A) is positioned on the upper side and the front plate laminate (50) is positioned on the lower side, thereby suppressing the remelting of the brazing material in the front plate laminate (50).

[0100] In this embodiment 1, the front connection portion (53) has an annular surface (72) that is continuous with the joint surface (71) between the front connection portion (53) and the heat transfer tube (42) and is annular when viewed from the front heat exchange portion (40A) side in the axial direction of the heat transfer tube (42), and the annular surface (72) has a brazing receiving portion (73). When the front connection portion (53) and the heat transfer tube (42) are brazed in a position where the front heat exchange portion (40A) is positioned on the upper side and the front plate laminate (50) is positioned on the lower side, the brazing receiving portion (73) can receive the molten brazing material (70). The brazing receiving portion (73) can suppress the dripping of the brazing material (70) downwards, thereby maintaining a high level of connection accuracy between the front connection portion (53) and the heat transfer tube (42).

[0101] In this embodiment 1, the width between the inner and outer edges of the annular surface (72) is 0.6-1.5 mm, so the brazing receiving portion (73) can be made as wide as possible, and the brazing material (70) can be received by the brazing receiving portion (73) as much as possible. As a result, dripping of the brazing material (70) is suppressed, and the connection accuracy between the front connection portion (53) and the heat transfer tube (42) can be maintained at a high level.

[0102] In this embodiment 1, since the insertion distance between the front connection part (53) and the heat transfer tube (42) is 2 mm or more, as much brazing material (70) as possible can flow between the front connection part (53) and the heat transfer tube (42), and the amount of brazing material (70) received by the brazing receiving part (73) can be reduced. As a result, dripping of the brazing material (70) is suppressed, and the connection accuracy between the front connection part (53) and the heat transfer tube (42) can be maintained at a high level.

[0103] In this embodiment 1, since the heat transfer tube (42) is inserted inside the front connection part (53), the brazing material (70) flows more easily between the front connection part (53) and the heat transfer tube (42), reducing the amount of brazing material (70) received by the brazing receiving part (73). As a result, dripping of the brazing material (70) is suppressed, and the connection accuracy between the front connection part (53) and the heat transfer tube (42) can be maintained at a high level.

[0104] <Embodiment 2> Embodiments of this disclosure will be described in detail with reference to the drawings. In the following description, parts common to Embodiment 1 will be denoted by the same reference numerals, and their detailed descriptions will be omitted.

[0105] (8) Connection part As shown in Figure 13, in this second embodiment, the front connection portion (253) of the front plate stack (250) is a cylindrical tube. The front connection portion (253) has a flared portion (253a) at the end facing the front heat exchange portion (40A). The flared portion (253a) has a tapered portion (253b) at its tip, which widens towards the tip. The inner diameter of the portion of the front connection portion (253) excluding the flared portion (253a) is smaller than the outer diameter of the heat transfer tube (42). The length of the flared portion (253a) is longer than the insertion distance between the front connection portion (253) and the heat transfer tube (42), for example, 2 mm or more.

[0106] The flared portion (253a) is located on the outside of the corresponding heat transfer tube (42). In other words, the heat transfer tube (42) is inserted inside the flared portion (253a). The insertion distance between the front connector (253) and the heat transfer tube (42) is 2 mm or more. The front connector (253) is joined to the corresponding heat transfer tube (42) at the position of the flared portion (253a) by burner brazing. The inner circumferential surface of the flared portion (253a) has a joint surface (271), which is the connection portion with the heat transfer tube (42). The outer circumferential surface of the heat transfer tube (42) and the joint surface (271) are spaced apart, and the brazing material (270) is located between the outer circumferential surface of the heat transfer tube (42) and the joint surface (271). The material of the brazing material (270) is the same as in the previously described Embodiment 1.

[0107] As shown in Figure 14, the inner circumferential surface of the tapered portion (253b) is an annular surface (272) 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 and outer ends of the annular surface (272) is the same as or greater than the wall thickness of the front connection portion (253). The width between the inner and outer ends 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 brazing receiving portion (273) that receives the molten brazing material (270).

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

[0110] (9) Effects of Embodiment 2 In this second embodiment, the front connection portion (253) is a cylindrical tube and has a flared portion (253a) at the end on the front heat exchange portion (40A) side, and the annular surface (272) is formed at the end of the flared portion (253a). This allows for a wide brazing receiving portion (273) on the annular surface (272), suppressing dripping of molten brazing material (270). This makes it possible to maintain a high level of connection accuracy between the front connection portion (253) and the heat transfer tube (42).

[0111] In this second embodiment, the tip of the flared portion (253a) is a tapered portion (253b) that widens towards the tip, and the annular surface (272) is the inner circumferential surface of the tapered portion (253b). When the front plate laminate (250) is positioned on the lower side and the front heat exchange portion (40A) is positioned on the upper side, and the brazing material (270) is placed on the annular surface (272) and melted, the brazing material (270) tends to flow downward along the annular surface. This makes it less likely for the molten brazing material (270) to leak out of the front connection portion (253), thus improving the connection accuracy between the front connection portion (253) and the heat transfer tube (42).

[0112] <Embodiment 3> Embodiment 3 of this disclosure will be described in detail with reference to the drawings. In the following description, parts common to Embodiments 1 to 3 will be denoted by the same reference numerals, and their detailed descriptions will be omitted.

[0113] (10) Connection part The front plate stack (350) according to this third embodiment has a different configuration from the front plate stack (350) according to the aforementioned embodiments 1 to 3. Specifically, the front plate stack (350) does not have a front connection portion (353) made of a circular tube, but rather a circular hole that penetrates the first front plate (3521). The thickness of the first front plate (3521) is the same as or thicker than 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 circumferential surface of the front connector (353) is located outside the corresponding heat transfer tube (42). In other words, the heat transfer tube (42) is inserted inside the front connector (353). The insertion distance between the front connector (353) and the heat transfer tube (42) is 2 mm or more. The front connector (353) is joined to the corresponding heat transfer tube (42) by burner brazing. The inner circumferential surface of the front connector (353) has a joint surface (371) which is the connection portion with the heat transfer tube (42). The outer circumferential surface of the heat transfer tube (42) and the joint surface (371) are spaced apart, and the brazing material (370) is located between the outer circumferential 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 Embodiment 1 described above.

[0115] As shown in Figures 15 and 16, the portion of the front connection portion (353) on the front heat exchange portion (40A) side is a stepped portion (353a). The stepped portion (353a) is a portion with a larger diameter than the rest of the front connection portion (353). The bottom surface of the stepped portion (353a) is an annular surface (372) 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 joint surface (371). The annular surface (372) surrounds the heat transfer tube (42) from the outside. The width between the inner and outer edges of the annular surface (372) is, for example, 0.6 mm to 1.5 mm. The height of the stepped 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 brazing receiving portion (373) that receives the molten brazing material (370).

[0117] Although not shown in the diagram, the rear connection portion, like the front connection portion (353), is composed of a circular hole that penetrates the first rear plate, and has a stepped portion on the rear heat exchange portion (40B) side. The stepped 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 the annular surface is the brazing receiving portion.

[0118] (11) Effects of Embodiment 3 In this third embodiment, the front connection portion (353) has a stepped portion (353a) on the front heat exchange portion (40A) side, and the brazing receiving portion (373) is the bottom surface of the stepped portion (353a). The presence of the stepped portion (353a) makes it difficult for the molten brazing material (370) to leak from the front connection portion (353) and makes it easier for the brazing receiving portion (373) to receive the molten brazing material (370). In addition, the brazing material (370) flows more easily into the gap between the front connection portion (353) and the heat transfer tube. This makes it possible to maintain a high level of connection accuracy between the front connection portion (353) and the heat transfer tube (42).

[0119] <Embodiment 4> Embodiment 4 of this disclosure will be described in detail with reference to the drawings. In the following description, parts common to Embodiments 1 to 4 will be denoted by the same reference numerals, and their detailed descriptions will be omitted.

[0120] (12) Connection part As shown in Figures 17 to 19, in this embodiment 4, the front connection portion (453) of the front plate stack (450) is a cylindrical tube. The front connection portion (453) has a constricted portion (453a) at the end facing the front heat exchange portion (40A) that is smaller in diameter than the rest of the portion. The base end of the constricted portion (453a) is a stepped portion (453b). The outer diameter of the constricted 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 constricted portion (453a) is larger than the inner diameter of the heat transfer tube (42). The length of the constricted portion (453a) is longer than the insertion distance between the front connection portion (453) and the heat transfer tube (42), for example, 2 mm or more.

[0121] The throttling portion (453a) is inserted inside the corresponding heat transfer tube (42). The insertion distance between the front connecting portion (453) and the heat transfer tube (42) is 2 mm or more. The front connecting portion (453) is joined to the corresponding heat transfer tube (42) at the position of the throttling portion (453a) by burner brazing. The outer circumferential surface of the throttling portion (453a) has a joint surface (471) which is the connection 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 Embodiment 1 described above.

[0122] As shown in Figure 18, the surface of the stepped portion (453b) is an annular surface (472) 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 and outer edges of the annular surface (472) is greater than the wall thickness of the heat transfer tube (42). The width between the inner and outer edges of the annular surface (472) is the same as or greater than the wall thickness of the front connection portion (453). The width between the inner and outer edges of the annular surface (472) is, for example, 0.6 mm to 1.5 mm. A portion of the annular surface (472) surrounds the heat transfer tube (42) from the outside.

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

[0124] Although not shown in the diagram, the rear connection section, like the front connection section (453), is composed of a cylindrical tube and also has a constricted section. The flared section also has a stepped section. The surface of the stepped section, when viewed from the rear heat exchange section (40B) side in the axial direction of the heat transfer tube (42), is an annular surface, and at least a part of the annular surface is a brazing receiving section.

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

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

[0127] Subsequently, the heat transfer tube (42) and the front connection part (453) are heated with a burner to melt the brazing material (470). The molten brazing material (470) is collected in the brazing collection part (473) and is drawn up into the gap between the front connection part (53) and the heat transfer tube (42) by capillary action, where it solidifies. Any brazing material (470) that is not drawn up and drips down is collected by the brazing collection part (473) and then solidifies.

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

[0129] (14) Effects of Embodiment 4 In this fourth embodiment, since the front connection portion (453) is inserted inside the heat transfer tube (42), when brazing the front connection portion (453) and the heat transfer tube (42) in a configuration where the indoor heat exchanger (40) is positioned above and the front plate laminate (450) is positioned below, there is a high possibility that the brazing material (470) will drip downwards. In contrast, by providing a constricted portion (453a) in the front connection portion (453), it is possible to form an annular surface (472) as wide as possible in the portion other than the constricted portion (453a). As a result, the brazing receiving portion (473) can be made as wide as possible, so that dripping of the brazing material (470) is suppressed and the connection accuracy between the front connection portion (453) and the heat transfer tube (42) can be maintained at a high level.

[0130] Furthermore, when brazing the front connector (453) and the heat transfer tube (42), heating the heat transfer tube (42) causes the brazing material (470) to melt from the heat transfer tube (42), making it easier for the molten brazing material (470) to be drawn into the gap between the front connector (53) and the heat transfer tube (42). This suppresses dripping of the brazing material (470), allowing for the maintenance of a high level of connection accuracy between the front connector (453) and the heat transfer tube (42).

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

[0132] The heat exchanger body (B) may not have a front heat exchange section (40A) and a rear heat exchange section (40B), but may have a single heat exchange section. In this case, the first internal piping (38), the second internal piping (39), and the indoor expansion valve (37) are omitted.

[0133] The configuration of the front connection section (53, 253, 353, 453) and the configuration of the rear connection section may differ. For example, the front connection section (253) may have a flared section (253a), while the rear connection section may not have a flared section.

[0134] The ring surface (72,272,372,472) does not have to be circular. The ring surface (72,272,372,472) may be elliptical or angular.

[0135] When the front connecting portion (253) has a flared portion (253a) as in Embodiment 2, or when the front connecting portion (453) has a constricted portion (453a) as in Embodiment 4, the wall thickness of the front connecting portions (253, 453) may be less than 0.6 mm.

[0136] The order of the steps for placing the brazing material (70, 270, 370, 470) and inserting the heat transfer tube (42) into the front connection section (53, 253, 353, 453) is not particularly limited. Alternatively, the heat transfer tube (42) may be inserted into the front connection section (53, 253, 353, 453) and then the brazing material (70, 270, 370, 470) may be placed on the annular surface (72, 272, 372, 472).

[0137] While embodiments and modifications have been described above, it will be understood that a variety of changes in form and details are possible without departing from the spirit and scope of the claims. Furthermore, the embodiments, modifications, and other embodiments described above may be combined or substituted as appropriate, as long as they do not impair the functions covered by this disclosure.

[0138] The designations "1st," "2nd," "3rd," etc., mentioned above are used to distinguish between the terms to which these designations are attached, and do not limit the number or order of those terms. [Industrial applicability]

[0139] As described above, this disclosure is useful for indoor heat exchangers, indoor air conditioning units, and methods for manufacturing indoor heat exchangers. [Explanation of Symbols]

[0140] 31 Casing 40 Indoor heat exchanger 40A Front heat exchanger 41 Fins 42 Heat transfer tubes 50 Front plate stack 51 Refrigerant flow path 53 Front connection section 70 wax 71 Joint surface 72 Annular surface 73. Brazing receiving section 250 Front plate stack 253 Front connection section 253a Flare section 270 wax 271 Joint surface 272 Annular surface 273 Brazing receiving section 350 Front plate stack 353 Front connection section 370 wax 371 Joint surface 372 Annular surface 373 Brazing receiving section 450 Front plate stack 453 Front connection section 453a Aperture section 470 wax 471 Joint surface 472 Annular surface 473 Brazing receiving section

Claims

1. A heat exchange section (40A) having fins (41) and heat transfer tubes (42), The plate laminate (50, 250, 350, 450) comprises a refrigerant flow path (51) communicating with the heat transfer tube (42), and a connecting portion (53, 253, 353, 453) communicating with the refrigerant flow path (51) and to which the heat transfer tube (42) is connected, and a plurality of plates (521, 522, 523, 524, 525, 3521) brazed together, The connecting portion (53,253,353,453) has a joining surface (71,271,371,471) to which the heat transfer tube (42) is joined, with the multiple plates (521,522,523,524,525,3521) brazed together, and an annular surface (72,272,372,472) that is continuous with the joining surface (71,271,371,471) and is annular when 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 receiving portion (73,273,373,473) that receives molten brazing material (70,270,370,470) and faces the heat exchange portion (40A).

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

3. In the heat exchanger according to claim 2, An indoor heat exchanger in which the 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 inserted inside the connection portion (53, 253).

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

6. An indoor heat exchanger according to any one of claims 1 to 3, An air conditioning indoor unit comprising a casing (31) that houses the indoor heat exchanger.

7. In the heat exchanger according to claim 1, The aforementioned connecting portion (53, 253, 453) is a connecting pipe that protrudes from the plate stack (50, 250, 450) toward the heat exchange portion (40A), The annular surface (72,272,472) is located on the heat exchange section (40A) side of the plate stack (50,250,450) in the indoor heat exchanger.

8. In the heat exchanger according to claim 1, The connecting portion (353) is a hole formed in the plate (3521), and has a stepped portion (353a) on the heat exchange portion (40A) side that is recessed on the opposite side from the heat exchange portion (40A). The annular surface (72,272,472) is the bottom surface of the stepped portion (353a) of the indoor heat exchanger.

9. A heat exchange section (40A) having fins (41) and heat transfer tubes (42), The plate laminate (50, 250, 350, 450) has a refrigerant flow path (51) that communicates with the heat transfer tube (42), and a connecting portion (53, 253, 353, 453) that communicates with the refrigerant flow path (51) and to which the heat transfer tube (42) is connected. The connecting portion (53,253,353,453) is continuous with the joining surface (71,271,371,471) between the connecting portion (53,253,353,453) and the heat transfer tube (42), and has an annular surface (72,272,372,472) when 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) has a brazing receiving portion (73,273,373,473) that receives the molten brazing material (70,270,370,470) and faces the heat exchange portion (40A), The width between the inner and outer edges of the aforementioned annular surface (72,272,372,472) is 0.6 mm to 1.5 mm. The aforementioned connecting portion (453) is a connecting pipe and has a constricted portion (453a) at the end on the heat exchange portion (40A) side. The aforementioned throttling portion (453a) is an indoor heat exchanger inserted inside the heat transfer tube (42).

10. A method for manufacturing an indoor heat exchanger, The aforementioned indoor heat exchanger is A heat exchange section (40A) having fins (41) and heat transfer tubes (42), The plate laminate (50, 250, 350, 450) comprises a refrigerant flow path (51) communicating with the heat transfer tube (42), and a connecting portion (53, 253, 353, 453) communicating with the refrigerant flow path (51) and to which the heat transfer tube (42) is connected, and a plurality of plates (521, 522, 523, 524, 525, 3521) brazed together, The connecting portion (53,253,353,453) has a joining surface (71,271,371,471) to which the heat transfer tube (42) is joined, and an annular surface (72,272,372,472) that is continuous with the joining surface (71,271,371,471) and is annular when viewed from the heat exchange portion (40A) side in the axial direction of the heat transfer tube (42). A first step involves arranging the plate stack (50, 250, 350, 450), in which multiple plates (521, 522, 523, 524, 525, 3521) are brazed together, on the lower side and arranging the heat exchange section (40A) on the upper side. A second step involves placing brazing material (70, 270, 370, 470) on the aforementioned annular surface (72, 272, 372, 472), A third step involves inserting one of the heat transfer tubes (42) and the connecting parts (53, 253, 353, 453) into the other of the heat transfer tubes (42) and the connecting parts (53, 253, 353, 453), A method for manufacturing an indoor heat exchanger, comprising a fourth step of melting the brazing material (70, 270, 370, 470) with a burner to join the connecting parts (53, 253, 353, 453) and the heat transfer tubes (42).

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