Heat exchanger and air conditioner

Abstract

A heat exchanger comprises: a heat exchange unit (40A, 40B) having fins (41) and a heat transfer tube (42) in which a first refrigerant flow path (42A) is formed; and a plate structure (50, 60) which is directly or indirectly connected to the heat transfer tube (42) and in which a second refrigerant flow path (51) is formed. The second refrigerant flow path (51) includes a first flow path section (71) that is connected to the outside of the plate structure (50, 60). A pipe (80, 42B) connected to the first refrigerant flow path (42A) and the second refrigerant flow path (51) includes a first section (81, 421) and a second section (82, 422) that is continuous with the first section (81, 421) and that has a flow path area smaller than that of the first section (81, 421). The first section (81, 421) is connected to the first flow path section (71).

Description

Heat exchanger and air conditioning device

[0001] The present disclosure relates to a heat exchanger and an air conditioning apparatus.

[0002] Patent Document 1 discloses a stacked header. In this stacked header, a bare material and a clad material having openings are stacked to form a refrigerant flow path. The refrigerant flow path has a shape in which the flow path area changes continuously in the stacking direction. Patent Document 1 discloses that, with this stacked header, the flow path area of ​​the refrigerant flow path formed in the stacked header changes continuously in the stacking direction, thereby reducing flow separation and vortex generation and reducing pressure loss in the flow path.

[0003] Patent No. 6116702

[0004] However, when the refrigerant is sent to the refrigerant flow path formed in the stacked header at a certain flow rate, the refrigerant is significantly affected by friction and collision with the wall surface of the refrigerant flow path, making it difficult to reduce the pressure loss of the refrigerant.

[0005] An object of the present disclosure is to make it possible to reduce the pressure loss of the refrigerant occurring within the plate structure.

[0006] A first aspect relates to a heat exchanger, the heat exchanger including: a heat exchange section (40A, 40B) having fins (41) and heat transfer tubes (42) having first refrigerant flow paths (42A) formed therein; and a plate structure (50, 60) directly or indirectly connected to the heat transfer tubes (42) and having second refrigerant flow paths (51) formed therein, the second refrigerant flow paths (51) including a first flow path portion (71) communicating with the outside of the plate structure (50, 60), a pipe (80, 42B) connecting the first refrigerant flow path (42A) and the second refrigerant flow path (51) including a first portion (81, 421) and a second portion (82, 422) connected to the first portion (81, 421) and having a flow path area smaller than that of the first portion (81, 421), the first portion (81, 421) being connected to the first flow path portion (71).

[0007] In the first aspect, the flow rate of the refrigerant can be reduced when the refrigerant flows from the second section (82, 422) to the first section (81, 421), thereby reducing the pressure loss of the refrigerant occurring within the plate structure (50, 60).

[0008] In a second aspect, in the first aspect, the pipe (80, 42B) is a part of the heat transfer tube (42) or a separate member from the heat transfer tube (42).

[0009] In the second embodiment, the heat transfer tubes (42) can be directly connected to the plate structures (50, 60), or can be indirectly connected to the plate structures (50, 60) via a member separate from the heat transfer tubes (42).

[0010] A third aspect is the first or second aspect, wherein the first portion (81, 421) is continuous with the second portion (82, 422) outside the plate structure (50, 60).

[0011] In the third aspect, the flow velocity of the refrigerant can be effectively reduced outside the plate structures (50, 60).

[0012] A fourth aspect is any one of the first to third aspects, wherein the second refrigerant flow path (51) includes a second flow path portion (72) communicating with the first flow path portion (71), and the flow path area of ​​the first portion (81, 421) is larger than the flow path area of ​​the second flow path portion (72).

[0013] In the fourth aspect, the flow path area of ​​the second flow path section (72) can be reduced, thereby making it possible to reduce the size of the plate structure (50, 60).

[0014] In a fifth aspect, in the fourth aspect, the diameter of a circle having the same area as the area of ​​a cross section of the second flow path portion (72) perpendicular to the direction (G) in which the second flow path portion (72) extends is 1.5 mm or more.

[0015] In the fifth aspect, it is possible to effectively reduce the pressure loss caused by the refrigerant impinging on the wall surface of the second refrigerant flow path (51) in the plate structure (50, 60).

[0016] A sixth aspect is any one of the first to fifth aspects, wherein the plate structure (50, 60) includes a plurality of plates (521, 522, 523, 524, 525, 621, 622, 623, 624, 625) stacked along a direction (F) in which the first flow path portion (71) extends, and a dimension (N) of each of the plurality of plates (521, 522, 523, 524, 525, 621, 622, 623, 624, 625) is 5 mm or less in the direction (F) in which the first flow path portion (71) extends.

[0017] In the sixth aspect, the plate structure (50, 60) can be made smaller in size in the stacking direction (F).

[0018] A seventh aspect is the fourth or fifth aspect, wherein the plate structure (50, 60) includes a plurality of plates (521, 522, 523, 524, 525, 621, 622, 623, 624, 625) stacked along a direction (F) in which the first flow path portion (71) extends, the second flow path portion (72) extends along a direction (G) perpendicular to the direction (F) in which the first flow path portion (71) extends, and a dimension (L1) of the second flow path portion (72) in a direction (H) perpendicular to the direction (F) in which the first flow path portion (71) extends and the direction (G) in which the second flow path portion (72) extends is equal to or greater than a dimension (L2) of the second flow path portion (72) in the direction (F) in which the first flow path portion (71) extends.

[0019] In the seventh aspect, the plate structure (50, 60) can be made smaller in size in the stacking direction (F).

[0020] An eighth aspect is any one of the first to seventh aspects, wherein the second refrigerant flow path (51) includes a second flow path portion (72) communicating with the first flow path portion (71), and the flow path area of ​​the first flow path portion (71) is larger than the flow path area of ​​a portion of the second flow path portion (72) located closer to the point of communication with the first flow path portion (71).

[0021] In the eighth aspect, the flow path area of ​​the second flow path section (72) can be reduced, thereby reducing the size of the plate structure (50, 60).

[0022] In a ninth aspect, in any one of the first to eighth aspects, the first refrigerant flow path (42A) of the heat transfer tube (42) and the second refrigerant flow path (51) are connected via a third refrigerant flow path (83) formed inside a connecting pipe (80) that is the pipe (80).

[0023] In the ninth aspect, the heat transfer tube (42) can be indirectly connected to the plate structure (50, 60) through a connecting pipe (80).

[0024] In a tenth aspect, in the ninth aspect, the first portion (81) has a larger dimension than the second portion (82) in the extending direction (F) of the pipe (80).

[0025] In the tenth aspect, the flow velocity of the refrigerant can be effectively reduced by the pipe (80, 42B), and the pressure loss of the refrigerant in the plate structure (50, 60) can be effectively reduced.

[0026] In an eleventh aspect, in the tenth aspect, the second part (82) of the connecting pipe (80) is connected to the heat transfer pipe (42), and the flow path area of ​​the heat transfer pipe (42) is equal to or greater than the flow path area of ​​the second part (82).

[0027] In the eleventh aspect, the second part (82) of the connecting pipe (80) can be connected to the heat transfer pipe (42) by inserting the second part (82) of the connecting pipe (80) into the heat transfer pipe (42).

[0028] A twelfth aspect is any one of the first to eleventh aspects, wherein the second refrigerant flow path (51) includes a second flow path portion (72) communicating with the first flow path portion (71), and has a shape that is bent at a communication point between the first flow path portion (71) and the second flow path portion (72), and a chamfered portion is provided on an inner portion (70a) of the bent portion (70) of the second refrigerant flow path (51), or a fillet portion is provided on an outer portion (70b) of the bent portion (70) of the second refrigerant flow path (51).

[0029] In the twelfth aspect, the refrigerant can be smoothly conveyed at the bent portion (70) of the second refrigerant flow path (51) due to the chamfered portion or fillet portion, so that the pressure loss due to collision of the refrigerant can be effectively reduced.

[0030] A thirteenth aspect is any one of the first to twelfth aspects, wherein the first flow path portion (71) includes a first portion (71b) and a second portion (71c) located further back in the plate structure (50, 60) than the first portion (71b), and a central axis (71b1) of the first portion (71b) and a central axis (71c1) of the second portion (71c) are eccentric to each other.

[0031] In the thirteenth aspect, the pressure loss of the refrigerant occurring in the plate structure (50, 60) can be effectively reduced.

[0032] A fourteenth aspect is any one of the first to thirteenth aspects, wherein a brazing material spot (R) is provided at a connection portion of the plate structure (50, 60) with the pipe (80, 42B).

[0033] In the fourteenth aspect, even if the brazing material rises into the second refrigerant flow path (51), the brazing material can be contained in the brazing material spot portion (R), thereby preventing the brazing material rising into the second refrigerant flow path (51) from increasing pressure loss of the refrigerant.

[0034] In a fifteenth aspect, in any one of the first to fourteenth aspects, when a row pitch of the plurality of pipes (80, 42B) is X, a row pitch of the plurality of pipes (80, 42B) is Y, and an outer diameter of the first portion (81, 421) is Z, X, Y, and Z satisfy the following condition (Equation 1): Z<√{(¼)X ２ +Y ２}

[0035] In the fifteenth aspect, it is possible to prevent the adjacent pipes (80, 42B) from interfering with each other.

[0036] A sixteenth aspect is any one of the first to fifteenth aspects, wherein the second refrigerant flow path (51) includes a second flow path portion (72) connected to the first flow path portion (71), and a corner portion (72b) of the second flow path portion (72) is curved when viewed from a direction (G) in which the second flow path portion (72) extends.

[0037] In the sixteenth aspect, the refrigerant can flow smoothly through the second flow path portion (72), and an increase in the pressure loss of the refrigerant can be suppressed.

[0038] A seventeenth aspect is directed to an air conditioner, the air conditioner including the heat exchanger according to any one of the first to sixteenth aspects.

[0039] FIG. 1 is a piping diagram of an air conditioning apparatus according to an embodiment. FIG. 2 is a front view of an air conditioning indoor unit. FIG. 3 is a cross-sectional view of the air conditioning indoor unit. FIG. 4 is a front view showing the internal structure of the air conditioning indoor unit. FIG. 5 is an enlarged perspective view of a portion of an indoor heat exchanger. FIG. 6 is a view of the plate structure as seen from the left side. FIG. 7 is a cross-sectional view illustrating an example of a refrigerant flow path of the plate structure. FIG. 8 is a partial perspective view of the front plate structure. FIG. 9 is a cross-sectional view along line IX-IX in FIG. 6. FIG. 10 is a view of the rear plate structure as seen from the right side. FIG. 11 is a cross-sectional view showing a connection structure between a heat transfer tube and a plate structure. FIG. 12(a) is a diagram showing the flow velocity distribution within the plate structure in a configuration in which a refrigerant is sent to a first flow path portion without reducing the refrigerant flow velocity. FIG. 12(b) is a diagram showing the pressure distribution within the plate structure in a configuration in which a refrigerant is sent to a first flow path portion without reducing the refrigerant flow velocity. FIG. 13(a) is a diagram showing the flow velocity distribution within the plate structure in a configuration in which a refrigerant is sent to a first flow path portion with a reduced refrigerant flow velocity. Fig. 13(b) is a diagram showing the pressure distribution within the plate structure in a configuration in which the refrigerant is sent to the first flow path portion with the flow rate of the refrigerant reduced. Fig. 14 is a cross-sectional view of the second flow path portion as viewed from a vertical direction. Fig. 15 is a perspective view showing other embodiments of the first flow path portion and the second flow path portion. Fig. 16 is a perspective view showing other embodiments of the first flow path portion. Fig. 17 is a cross-sectional view showing other embodiments of the first flow path portion. Fig. 18 is a cross-sectional view showing a brazing material spot portion. Fig. 19 is a diagram showing an example of a connection mode of a plurality of connection pipes to the plate structure. Fig. 20 is a cross-sectional view of the second flow path portion as viewed from a vertical direction. Fig. 21 is a cross-sectional view showing a modified example of the connection structure between a heat transfer tube and a plate structure.

[0040] Hereinafter, 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 concept of the present disclosure. Since the drawings are intended to conceptually explain the present disclosure, dimensions, ratios, or numbers may be exaggerated or simplified as necessary to facilitate understanding.

[0041] (1) Overall Configuration of Air Conditioner This 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.

[0042] As shown in Fig. 1, the air conditioner (10) is an example of a refrigeration cycle apparatus 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.

[0043] 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.

[0044] 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).

[0045] 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 selector valve (24) switches between a first state (the state indicated by the solid line in FIG. 1 ) and a second state (the state indicated by the dashed line in FIG. 1 ). In the first state, the four-way selector valve (24) communicates the discharge port of the compressor (21) with the gas end of the outdoor heat exchanger (22) and also communicates the suction port of the compressor (21) with the first connecting pipe (12). The four-way selector valve (24) in the second state communicates the discharge port of the compressor (21) with the first connecting pipe (12) and also communicates the suction port 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.

[0046] 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).

[0047] (2) Air Conditioning Indoor Unit The indoor unit (30) serving as an indoor air conditioner will be described in detail with reference to Figures 2 to 4. The indoor unit (30) of this 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" used below correspond to the directions of the arrows shown in Figures 2 and 3, and the left-right directions are based on the case where the casing (31) is viewed from the front.

[0048] 2 and 3, the casing (31) is formed in the shape of a horizontally long box. The casing (31) 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).

[0049] 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).

[0050] An air inlet (33) is formed in the upper plate (31c), and an air outlet (34) is formed in the lower plate (31d). An air flow path (P) is formed inside the casing (31) from the air inlet (33) to the air outlet (34). The air inlet (33) extends in the longitudinal direction of the casing (31). The air inlet (33) is an opening for taking air from the indoor space (I) into the air flow path (P). An air outlet (34) is formed in the lower plate (31d). The air outlet (34) extends in the longitudinal direction of the casing (31). The air outlet (34) is an opening for blowing air from the air flow path (P) into the indoor space.

[0051] (2-2) Filter The indoor unit (30) includes a filter (35). The filter (35) is located at the back of the air inlet (33) and upstream of the indoor heat exchanger (40). The filter (35) collects dust in the air sent from the air inlet (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).

[0052] (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 structures (50, 60). The heat exchanger body (B) of the indoor heat exchanger (40) is disposed so as to cross the air flow path (P). The air flow path (P) is divided into an upstream side and a downstream side of the heat exchanger body (B).

[0053] (2-4) Indoor Fan The indoor fan (32) is arranged in the air flow path (P). The indoor fan (32) is arranged in the air flow path (P) downstream of the indoor heat exchanger (40). 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).

[0054] (2-5) Flap The indoor unit (30) has a flap (36) that adjusts the direction of air blown out from 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.

[0055] (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).

[0056] (3-1) Indoor Heat Exchanger The indoor heat exchanger (40) shown in Figures 3 to 5 includes a heat exchanger body (B) and plate structures (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.

[0057] 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). The plate structure (50, 60) has therein second refrigerant flow paths (51, 61) directly or indirectly connected to the heat transfer tubes (42). In this embodiment, the second refrigerant flow paths (51, 61) of the plate structure (50, 60) are indirectly connected to the heat transfer tubes (42) via a connecting pipe (80).

[0058] 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.

[0059] The heat transfer tubes (42) are straight tubes. The heat transfer tubes (42) are made of an aluminum alloy. A first refrigerant flow path (42A) is formed inside the heat transfer tubes (42). The heat transfer tubes (42) extend parallel to one another and penetrate the fins (41). One end of each heat transfer tube (42), i.e., a right end, protrudes to the right of the fins (41). One end of each heat transfer tube (42) is directly or indirectly connected to the plate structure (50, 60). Of the other end of each heat transfer tube (42), i.e., the left end of two adjacent heat transfer tubes (42), is 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 seamlessly formed integrally.

[0060] The indoor heat exchanger (40) of this embodiment includes a heat exchange section. The heat exchange section has a front heat exchange section (40A) that is a first heat exchange section and a rear heat exchange section (40B) that 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 aligned 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) sandwiched between them.

[0061] The front heat exchange section (40A) includes a front main heat exchange section (43), a first auxiliary heat exchange section (44), a second auxiliary heat exchange section (45), and a tube plate (49).

[0062] The tube plate (49) is arranged so that its plate surface extends in the up-down direction and the front-rear direction, and is located on the right side of the plurality of fins (41). The tube plate (49) faces the front plate structure (50). A plurality of heat transfer tubes (42) penetrate the tube plate (49). There is almost no gap between the tube plate (49) and each heat transfer tube (42), and the tube plate (49) supports the fins (41) and the plurality of heat transfer tubes (42). The U-shaped tubes (48), the first connecting pipe (12), and the front plate structure (50) are arranged on the right side of the tube plate (49), i.e., on the opposite side of the tube plate (49) from the plurality of fins (41).

[0063] 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 a V-shaped outer shape when viewed in the longitudinal direction of the heat transfer tubes (42). The tip of the V faces forward.

[0064] 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 second auxiliary heat exchange section (45) is provided on the inlet side (front side) of the second front main heat exchange section (43b). The rear heat exchange section (40B) has a rear main heat exchange section (46), a third auxiliary heat exchange section (47), and a tube plate. The rear main heat exchange section (46) is disposed closer to the indoor fan (32) in the rear heat exchange section (40B). The third auxiliary heat exchange section (47) is provided on the inlet side (rear side) of the rear main heat exchange section (46). The tube plate of the rear heat exchange section (40B) faces the rear plate structure (60).

[0065] The plate structures (50, 60) are disposed to the right of the rightmost fin (41) and parallel to the fin (41). The plate structures (50, 60) are connected to one ends of the heat transfer tubes (42). As shown in Fig. 5, the plate structures (50, 60) include a front plate structure (50) connected to the heat transfer tubes (42) of the front heat exchange section (40A) and a rear plate structure (60) connected to the heat transfer tubes (42) of the rear heat exchange section (40B).

[0066] (3-2) Indoor Expansion Valve, Gas Relay Pipe, and Liquid Relay Pipe The indoor expansion valve (37) is an electronic expansion valve with a variable opening. The indoor expansion valve (37) is disposed on the right side of the plate structures (50, 60). The indoor expansion valve (37) is connected to the front plate structure (50) via a first internal pipe (38) and to the rear plate structure (60) via a second internal pipe (39).

[0067] One end of the gas relay pipe (12a) is connected to the rear plate structure (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 structure (50). The other end of the liquid relay pipe (13a) is connected to the second connecting pipe (13) via a joint.

[0068] (4) Plate Structure The plate structures (50, 60) will be described in detail with reference to FIGS. 5 to 10.

[0069] (4-1) Front Plate Structure The front plate structure (50) includes a front main body portion (52) having a second refrigerant flow path (51) therein, 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).

[0070] As shown in FIGS. 5 and 8 , 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 structure (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 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 members having the same outer edge shape. Each front plate is made of the same material as the heat transfer tubes (42). In this embodiment, the front plates are made of an aluminum alloy. The front plates are joined to each other by furnace brazing. The number of front plates is an example, and the number 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.

[0071] 5, the front relay portion (54) is a circular pipe. The front relay portion (54) is provided on the fifth front plate (525). The front relay portion (54) is joined to the front end of the first internal pipe (38) by brazing.

[0072] The liquid end portion (55) is a circular pipe and is provided on the fifth front plate (525). The liquid end portion (55) is joined to the end portion of the liquid relay pipe (13a) by brazing.

[0073] (4-2) Rear Plate Structure The rear plate structure (60) includes a rear main body portion (62) having a second refrigerant flow path (61) therein, a rear relay portion (64) to which the second internal piping (39) is connected, and a gas end portion (65) communicating with the first connection piping (12) via a gas relay pipe (12a).

[0074] The rear body portion (62) has basically the same configuration as the front body portion (52), except for the shape of the outer edge of the plate as viewed in the axial direction of the heat transfer tubes (42) and the internal second refrigerant flow path (61). 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 structure (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). The rear plates are made of the same material as the heat transfer tubes (42). In this embodiment, the rear plates are made of an aluminum alloy. 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 less or six or more. The number of front plates may be different from the number of rear plates. Hereinafter, when it is not necessary to distinguish between the respective rear plates, they will simply be referred to as rear plates.

[0075] 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). The rear relay portion (64) is joined to the end of the second internal pipe (39) by brazing.

[0076] The gas end portion (65) is a circular pipe and is provided on the fifth rear plate (625). The gas end portion (65) is joined to the end portion of the gas relay pipe (12a) by brazing.

[0077] (5) Operation The air conditioner (10) performs cooling operation, heating operation, and dehumidifying operation.

[0078] (5-1) Cooling Operation In 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 Figure 1), appropriately adjusts the opening of the outdoor expansion valve (23), and fully opens the indoor expansion valve (37).

[0079] During 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.

[0080] The indoor unit (30) draws indoor air from the indoor space (I) into the air flow path (P) through the inlet (33). The air in the air flow path (P) is cooled by the indoor heat exchanger (40). The cooled air is supplied to the indoor space (I) through the outlet (34).

[0081] (5-2) Heating Operation In heating operation, the controller of the air conditioner (10) operates the compressor (21), the outdoor fan (25), and the indoor fan (32), places the four-way switching valve (24) in the second state (the state shown by the dashed line in FIG. 1), adjusts the opening of the outdoor expansion valve (23) to a predetermined opening, and fully opens the indoor expansion valve (37).

[0082] During 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.

[0083] The indoor unit (30) draws indoor air from the indoor space (I) into the air flow path (P) through the inlet (33). The air in the air flow path (P) is heated by the indoor heat exchanger (40). The heated air is supplied to the indoor space (I) through the outlet (34).

[0084] (5-3) Dehumidifying Operation In the dehumidifying 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 Figure 1), and appropriately adjusts the apertures of the outdoor expansion valve (23) and the indoor expansion valve (37).

[0085] 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.

[0086] The indoor unit (30) draws room air from the indoor space (I) into the air flow path (P) through the air inlet (33). The rear heat exchanger (40B) cools the air in the air flow path (P) to a temperature below the dew point. The front heat exchanger (40A) heats the air in the air flow path (P). The air passing through both the rear heat exchanger and the front heat exchanger mixes in the air flow path (P) to produce low-humidity air. The air dehumidified in this manner is supplied to the indoor space (I) through the air outlet (34).

[0087] (6) Connection structure between heat transfer tubes and plate structures Hereinafter, the direction in which the multiple plates (521, 522, 523, 524, 525) of the front plate structure (50) are stacked and the direction in which the multiple plates (621, 622, 623, 624, 625) of the rear plate structure (60) are stacked may be collectively referred to as the stacking direction (F).

[0088] 11 , in this embodiment, the fins (41) and the plate structures (50, 60) are arranged at an interval along the stacking direction (F). The plate structures (50, 60) are located on one side (F1) of the fins (41) and the plate structures (50, 60) in the stacking direction (F), and the fins (41) are located on the other side (F2) of the stacking direction (F).

[0089] The heat transfer tube (42) includes one end (42B). The one end (42B) of the heat transfer tube (42) is a portion of the heat transfer tube (42) that protrudes from the fin (41) toward the plate structure (50, 60). The one end (42B) of the heat transfer tube (42) includes a first cylindrical portion (42a), a first expanded diameter portion (42b), a second cylindrical portion (42c), and a second expanded diameter portion (42d). The first cylindrical portion (42a) is a cylindrical member that extends along the stacking direction (F) and has a constant inner diameter. The first expanded diameter portion (42b) is a cylindrical member that is continuous with an end of the first cylindrical portion (42a) on one side (F1) in the stacking direction (F) and whose inner diameter gradually increases toward the one side (F1) in the stacking direction (F). The second cylindrical portion (42c) is a cylindrical member having a constant inner diameter and continuing from an end portion of the first expanded diameter portion (42b) on one side (F1) in the stacking direction (F). The inner diameter of the second cylindrical portion (42c) is larger than the inner diameter of the first cylindrical portion (42a). The second expanded diameter portion (42d) is a cylindrical member continuing from an end portion of the second cylindrical portion (42c) on one side (F1) in the stacking direction (F), and the inner diameter gradually increases toward the one side (F1) in the stacking direction (F). An opening (42d1) is formed at the end portion of the second expanded diameter portion (42d) on the one side (F1) in the stacking direction (F), which communicates with the first refrigerant flow path (42A) of the heat transfer tube (42) and the outside of the heat transfer tube (42).

[0090] The second refrigerant flow path (51, 61) formed inside the plate structure (50, 60) includes a first flow path portion (71) and a second flow path portion (72). The second flow path portion (72) communicates with the first flow path portion (71). The second refrigerant flow path (51, 61) has a bent shape at a point where the first flow path portion (71) communicates with the second flow path portion (72).

[0091] The first flow path portion (71) of the front plate structure (50) is a hole penetrating the front plates (521, 522) in the stacking direction (F). The first flow path portion (71) of the rear plate structure (60) is a hole penetrating the rear plates (621, 622) along the stacking direction (F). The second flow path portion (72) of the front plate structure (50) is a hole formed between the first front plate (521) and the third front plate (523) and penetrating the second front plate (522) in the stacking direction (F). The second flow path portion (72) of the rear plate structure (60) is a hole formed between the first rear plate (621) and the third rear plate (623) and penetrating the second rear plate (622) along the stacking direction (F).

[0092] The first flow path portion (71) is a portion of the refrigerant flow path (51, 61) that extends linearly and communicates with the outside of the plate structure (50, 60). In this embodiment, the first flow path portion (71) extends along the stacking direction (F). The first flow path portion (71) has an opening (71a) at an end portion on the other side (F2) of the stacking direction (F) and communicates with the outside of the plate structure (50, 60) through the opening (71a). The second flow path portion (72) communicates with an end portion of the first flow path portion (71) on one side (F1) of the stacking direction (F). The second flow path portion (72) extends in a direction different from the stacking direction (F). In this embodiment, the second flow path portion (72) extends along a vertical direction (G) that is perpendicular to the stacking direction (F).

[0093] In this embodiment, the cross section of the first flow path section (71) perpendicular to the direction in which the first flow path section (71) extends (stacking direction (F)) is circular, and the cross section of the second flow path section (72) perpendicular to the direction in which the second flow path section (72) extends (vertical direction (G)) is rectangular.

[0094] The indoor heat exchanger (40) includes a connecting pipe (80). The connecting pipe (80) is a cylindrical member having open ends. The connecting pipe (80) is made of an aluminum alloy. The connecting pipe (80) is disposed between the plate structures (50, 60) and the heat transfer pipe (42) and indirectly connects the plate structures (50, 60) and the heat transfer pipe (42). The connecting pipe (80) connects the first refrigerant flow path (42A) and the first flow path portion (71) of the second refrigerant flow path (51, 61). The connecting pipe (80) is a first example of a pipe and is a member separate from the heat transfer pipe (42). A third refrigerant flow path (83) is formed inside the connecting pipe (80). The third refrigerant flow path (83) extends along the stacking direction (F). The third refrigerant flow path (83) communicates with the first refrigerant flow path (42A) and the first flow path portion (71) of the second refrigerant flow path (51, 61). In this embodiment, the third refrigerant flow path (83) has a circular cross section perpendicular to the direction in which the third refrigerant flow path (83) extends (stacking direction (F)).

[0095] The connecting pipe (80) includes a first portion (81) and a second portion (82) connected to the first portion (81). The tip of the first portion (81) is inserted into the plate structure (50, 60) through an opening (71a) of the plate structure (50, 60) and joined to the plate structure (50, 60) by, for example, furnace brazing or burner brazing. The first portion (81) is connected to the second portion (82) outside the plate structure (50, 60). The second portion (82) is inserted into the heat transfer tube (42) through an opening (42d1) of the heat transfer tube (42) and joined to the heat transfer tube (42) by, for example, furnace brazing or burner brazing.

[0096] The third refrigerant flow path (83) includes a first piping flow path portion (83a) formed inside the first portion (81) and a second piping flow path portion (83b) formed inside the second portion (82). The first piping flow path portion (83a) and the second piping flow path portion (83b) each extend along the stacking direction (F). The first portion (81) is connected to the first flow path portion (71) of the plate structure (50, 60), thereby communicating the first piping flow path portion (83a) with the first flow path portion (71). The second portion (82) is connected to the first portion (81), thereby communicating the first piping flow path portion (83a) with the second piping flow path portion (83b). The first piping flow path portion (83a) communicates with the second piping flow path portion (83b) outside the plate structure (50, 60). The second section (82) is connected to the first refrigerant flow path (42A) of the heat transfer tube (42), so that the second piping flow path section (83b) communicates with the first refrigerant flow path (42A).

[0097] The flow path area of ​​the second portion (82) is smaller than the flow path area of ​​the first portion (81). The flow path area is the area of ​​a cross section of a refrigerant flow path perpendicular to the extension direction of the flow path. In other words, the extension direction of the flow path is the direction in which the refrigerant flows. The flow path area of ​​the first portion (81) refers to the flow path area of ​​a first piping flow path portion (83a) formed inside the first portion (81). The flow path area of ​​the first portion (81) refers to the area of ​​a cross section of the first piping flow path portion (83a) perpendicular to the extension direction of the first piping flow path portion (83a) (stacking direction (F)). The flow path area of ​​the second portion (82) refers to the flow path area of ​​a second piping flow path portion (83b) formed inside the second portion (82) and refers to the area of ​​a cross section of the second piping flow path portion (83b) perpendicular to the extension direction of the second piping flow path portion (83b) (stacking direction (F)). Each of the first piping flow path portion (83a) and the second piping flow path portion (83b) has a constant flow path area. The first piping flow path portion (83a) and the second piping flow path portion (83b) communicate with each other outside the plate structure (50, 60). The outside of the plate structure (50, 60) refers to the outside of the second refrigerant flow path (51, 61). At the communication point between the first piping flow path portion (83a) and the second piping flow path portion (83b), the flow path area gradually increases from the second piping flow path portion (83b) toward the first piping flow path portion (83a).

[0098] (7) Advantages of the Embodiment As described above, the connection pipe (80) includes the first portion (81) and the second portion (82) that is continuous with the first portion (81) and has a smaller flow path area than the first portion (81), and the first portion (81) is connected to the first flow path portion (71). With this configuration, when the refrigerant is sent from the second piping flow path portion (83b) formed in the second portion (82) to the first piping flow path portion (83a) formed in the first portion (81), the flow path area increases, and the flow rate of the refrigerant decreases. Specifically, the flow rate of the refrigerant is lower when the refrigerant is flowing through the first piping flow path portion (83a) than when the refrigerant is flowing through the second piping flow path portion (83b). The refrigerant flowing through the first piping flow path (83a) is sent from the first piping flow path (83a) to the second refrigerant flow path (51, 61) of the plate structure (50, 60) and then separated at a bend (70) (a communication point between the first flow path (71) and the second flow path (72)) of the second refrigerant flow path (51, 61) (see the unevenness in the refrigerant flow velocity distribution at the bend (70) of the second refrigerant flow path (51, 61) shown in FIG. 13( a) ). This causes a pressure loss resulting from a decrease in the pressure of the refrigerant. However, in this embodiment, the flow path area of ​​the second portion (82) is made smaller than the flow path area of ​​the first portion (81) as described above, thereby reducing the flow velocity of the refrigerant and allowing the refrigerant with the reduced flow velocity to be sent to the bend (70) of the second refrigerant flow path (51, 61). This reduces the effect of the separation on the refrigerant and reduces the pressure loss of the refrigerant within the plate structure (50, 60). Reducing the pressure loss of the refrigerant means reducing the degree of reduction in the pressure of the refrigerant. Furthermore, by making the flow path area of ​​the second portion (82) smaller than the flow path area of ​​the first portion (81) as described above and sending the refrigerant with a reduced flow velocity to the second refrigerant flow path (51, 61) of the plate structure (50, 60), it is possible to reduce the pressure loss of the refrigerant (collision pressure loss) caused by the refrigerant colliding with the wall surface of the second refrigerant flow path (51, 61).

[0099] (8) Analysis Results The following describes the analysis results conducted by the present inventors with reference to Figures 12(a) to 13(b). Figures 12(a) and 12(b) show the analysis results for a configuration that does not employ the configuration of this embodiment (a configuration in which a refrigerant is sent to the first flow path portion (71) without reducing the flow velocity of the refrigerant). In the configurations shown in Figures 12(a) and 12(b), the refrigerant is sent to the inside of the plate structure (50, 60) through the refrigerant flow path (83c), flows through the first flow path portion (71), the second flow path portion (72), and the third flow path portion (73) in that order within the plate structure (50, 60), and is then sent to another refrigerant flow path (83c). 12(a) and 12(b), the flow path area of ​​the refrigerant flow path (83c) is the same as the flow path area of ​​the flow path portions (71, 73) of the plate structures (50, 60), so that the refrigerant flowing through the refrigerant flow path (83c) is sent to the first flow path portion (71) without decreasing its flow velocity. Figures 13(a) and 13(b) show analysis results for the configuration of this embodiment (a configuration in which the flow path area of ​​the piping flow path portions (83a, 83b) of the third refrigerant flow path (83) is changed to decrease the flow velocity of the refrigerant so that the refrigerant is sent to the first flow path portion (71)). 13(a) and 13(b), the refrigerant is sent through the third refrigerant flow path (83) into the plate structure (50, 60), flows through the first flow path portion (71), the second flow path portion (72), and the third flow path portion (73) in that order inside the plate structure (50, 60), and is then sent to another third refrigerant flow path (83). In Figures 12(a) to 13(b), the direction indicated by the arrow in the second refrigerant flow path (51, 61) indicates the direction in which the refrigerant flows.

[0100] As shown in Figures 12(a) and 13(a), it was confirmed that at the bend (70) of the second refrigerant flow path (51, 61), the refrigerant flow separates from the flow along the wall surface of the second refrigerant flow path (51, 61), causing unevenness in the flow velocity distribution of the refrigerant.

[0101] As shown in Figure 12 (b), when refrigerant is sent to the first flow path section (71) without reducing the flow rate of the refrigerant, it was confirmed that the pressure of the refrigerant flowing through the first flow path section (71) is within the first range (M1), the pressure of the refrigerant flowing through the second flow path section (72) is within the second range (M2), and the pressure of the refrigerant flowing through the third flow path section (73) is within the third range (M3).

[0102] As shown in Figure 13 (b), when refrigerant is sent to the first flow path section (71) while the flow rate of the refrigerant is reduced by making the flow path area of ​​the second section (82) smaller than the flow path area of ​​the first section (81), it was confirmed that the pressure of the refrigerant flowing through the first flow path section (71) is within the fourth range (M4), and the pressure of the refrigerant flowing through the second flow path section (72) and the third flow path section (73) is within the second range (M2).

[0103] From the above, the inventors of the present application have confirmed that, when comparing the analysis results for the case where the flow velocity of the refrigerant sent to the second refrigerant flow path (51, 61) of the plate structure (50, 60) is not reduced (see Figure 12(b)) with the analysis results for the case where the flow velocity is reduced (see Figure 13(b)), the degree of change in the pressure of the refrigerant flowing through the second refrigerant flow path (51, 61) is smaller when the flow velocity is reduced, and that the pressure loss of the refrigerant occurring within the plate structure (50, 60) can be effectively reduced.

[0104] (9) Other Embodiments As shown in FIGS. 7 , 9 , and 11 , the flow path area of ​​the first portion (81) (first piping flow path portion (83a)) may be larger than the flow path area of ​​the second flow path portion (72) of the second refrigerant flow path (51, 61). The flow path area of ​​the second flow path portion (72) is the area of ​​a cross section of the second flow path portion (72) perpendicular to the direction in which the second flow path portion (72) extends (the vertical direction (G)). This makes it possible to make the flow path area of ​​the second flow path portion (72) smaller than the flow path area of ​​the first flow path portion (71), and thereby to form the second flow path portion (72) narrower so that the width of the second flow path portion (72) in the stacking direction (F) does not increase. As a result, an increase in the dimension of the plate structure (50, 60) in the stacking direction (F) can be suppressed, and the plate structure (50, 60) can be made smaller in size in the stacking direction (F).

[0105] 11 , the diameter of a circle having the same area as the cross-sectional area perpendicular to the extension direction (vertical direction (G)) of the second flow path portion (72) may be 1.5 mm or more. Hereinafter, the diameter of the circle may be referred to as the diameter of the second flow path portion (72). According to this, at a communication point between the first piping flow path portion (83a) and the second piping flow path portion (83b), the refrigerant flow direction changes, causing a refrigerant impingement pressure loss. However, by setting the diameter of the second flow path portion (72) to 1.5 mm or more, it is possible to effectively ensure space at the communication point, thereby reducing the refrigerant impingement pressure loss at the communication point.

[0106] 11 , the dimension N of each of the plurality of plates (521, 522, 523, 524, 525, 621, 622, 623, 624, 625) in the direction in which the first flow path portion (71) extends (stacking direction (F)) may be 5 mm or less (N≦5), thereby enabling the plate structure (50, 60) to be reduced in size in the stacking direction (F).

[0107] 14 , in the second flow path portion (72), a dimension L1 in a direction (width direction (H)) perpendicular to the direction (stacking direction (F)) in which the first flow path portion (71) extends and the direction (vertical direction (G)) in which the second flow path portion (72) extends may be equal to or greater than a dimension L2 in the direction (stacking direction (F)) in which the first flow path portion (71) extends (L1≧L2). In this way, by increasing the dimension L1 in the width direction (H) of the second flow path portion (72), the flow path area of ​​the second flow path portion (72) can be ensured, and by reducing the dimension L2 in the stacking direction (F), the plate structure (50, 60) can be made smaller in size in the stacking direction (F).

[0108] 15 , the flow path area of ​​the first flow path portion (71) may be larger than the flow path area of ​​a portion (72a) of the second flow path portion (72) that is located closer to the communication point with the first flow path portion (71). The flow path area of ​​the first flow path portion (71) is the area of ​​a cross section of the first flow path portion (71) perpendicular to the extension direction of the first flow path portion (71) (stacking direction (F)). This allows the flow path area of ​​the second flow path portion (72) to be reduced, thereby reducing the size of the plate structure (50, 60).

[0109] The dimension of the first portion (81) may be greater than the dimension of the second portion (82) in the extending direction (stacking direction (F)) of the connecting pipe (80), which is a pipe. This allows the connecting pipe (80) to effectively reduce the flow velocity of the refrigerant, and effectively reduces the pressure loss of the refrigerant in the plate structure (50, 60).

[0110] 11 , the flow path area of ​​the heat transfer pipe (42) may be equal to or larger than the flow path area of ​​the second portion (82) of the connecting pipe (80). In other words, the flow path area of ​​the first refrigerant flow path (42A) may be equal to or larger than the flow path area of ​​the second pipe flow path portion (83b). In this way, the second portion (82) of the connecting pipe (80) can be connected to the heat transfer pipe (42) by inserting the second portion (82) of the connecting pipe (80) into the heat transfer pipe (42).

[0111] As shown in FIG. 11 , an inner portion (70a) of the bent portion (70) of the second refrigerant flow path (51, 61) may be provided with a chamfered portion. The chamfered portion has a shape in which the corners of the wall surface forming the inner portion (70a) of the bent portion (70) of the plate structure (50, 60) are formed into an angled flat surface such as a C-surface (cornered surface) or an R-surface (rounded surface). Furthermore, a fillet may be provided on the outer portion (70b) of the bent portion (70) of the second refrigerant flow path (51, 61). The fillet has a curved shape obtained by rounding the corners of the wall surface forming the inner portion (70a) of the bent portion (70) of the connecting pipe (80) (or one end (42B) of the heat transfer tube (42) described later). This allows the refrigerant to be smoothly transported at the bent portion (70) of the second refrigerant flow path (51, 61) due to the chamfered portion or fillet portion, thereby effectively reducing the pressure loss due to collision of the refrigerant.

[0112] As shown in Figures 16 and 17, the first flow path section (71) includes a first portion (71b) and a second portion (71c) located at a rear side of the first portion (71b) in the plate structure (50, 60). The central axis (71b1) of the first portion (71b) and the central axis (71c1) of the second portion (71c) may be eccentric to each other. In this case, the flow path area of ​​the first portion (71b) is smaller than the flow path area of ​​the second portion (71c). The first portion (71b) is connected to the first part (81) of the connecting pipe (80) and communicates with the first pipe flow path section (83a). The second portion (71c) communicates with the second flow path section (72). This increases the flow path area when the refrigerant is sent from the first portion (71b) to the second portion (71c), thereby effectively reducing the flow rate of the refrigerant and effectively reducing the pressure loss of the refrigerant that occurs within the plate structure (50, 60).

[0113] 18 , a brazing material spot (R) may be provided at a connection point between the second refrigerant flow path (51, 61) and the connecting pipe (80). The brazing material spot (R) is a groove formed in a wall surface of the plate structure (50, 60) that forms the second refrigerant flow path (51, 61) at a connection point with the connecting pipe (80). This allows the brazing material to be contained in the brazing material spot (R) even if the brazing material rises into the second refrigerant flow path (51, 61), thereby preventing an increase in refrigerant pressure loss due to the brazing material rising into the second refrigerant flow path (51, 61).

[0114] As shown in Fig. 19, when the connection locations of the plurality of connection pipes (80) to the plate structure (50, 60) are staggered, where the row pitch of the plurality of connection pipes (80) is X, the row pitch of the plurality of connection pipes (80) is Y, and the outer diameter of the first portion (81) is Z, X, Y, and Z may be configured to satisfy the following condition. This makes it possible to prevent adjacent connection pipes (80) from interfering with each other. (Equation 1) Z<√{(1 / 4)X ２ +Y ２}

[0115] 20 , the corners (72b) of the second flow path portion (72) may be curved when viewed from the direction in which the second flow path portion (72) extends. For example, the corners (72b) of the second flow path portion (72) may be curved in a circular or elliptical arc shape. This allows the refrigerant to flow smoothly through the second flow path portion (72) and prevents an increase in pressure loss of the refrigerant.

[0116] The indoor heat exchanger (40) does not have to be of a fin-and-tube type, but may be of a corrugated type in which corrugated fins are arranged between adjacent heat transfer tubes.

[0117] The heat transfer tubes (42) of the heat exchanger body (B) may be made of a copper alloy instead of an aluminum alloy. When the heat transfer tubes (42) are made of a copper alloy, it is preferable that the plate structures (50, 60) are also made of a copper alloy.

[0118] The heat transfer tube (42) may be a flat tube. The cross-sectional shape of the flat tube, taken perpendicular to the axial direction, is an ellipse, an oval, or a substantially rectangular shape extending along the air flow direction. Strictly speaking, the flat tube is a flat multi-hole tube having a plurality of flow paths through which the refrigerant flows.

[0119] A header collecting pipe connected to the heat transfer tubes (42) may be provided at the other left end of the indoor heat exchanger (40). In this case, the header collecting pipe is provided instead of the U-shaped pipe (48) of the above-described embodiment. The header collecting pipe has a refrigerant flow path formed therein that communicates with the heat transfer tubes (42). The header collecting pipe is formed in a tubular shape with both axial ends closed. The header collecting pipe is formed in a cylindrical or rectangular tubular shape.

[0120] The connecting pipe (80) may be made of a copper alloy or stainless steel (SUS) material instead of aluminum. In this case, the plate structures (50, 60) are preferably made of the same material as the connecting pipe (80).

[0121] The plate structure (50, 60) may be formed of a single plate. The plate structure (50, 60) of the modified example has a second refrigerant flow path (51, 61) formed therein, similar to the above-described embodiment. The plate structure (50, 60) of the modified example is manufactured by sintering metal powder using, for example, a 3D printer.

[0122] Two or more of the configurations shown in "(9) Other embodiments" above may be combined and adopted.

[0123] (10) Modifications In this embodiment, the heat transfer tube (42) is indirectly connected to the first flow path portion (71) of the plate structure (50, 60) via the connection pipe (80). However, the present invention is not limited to this. As a modification of the above embodiment, the heat transfer tube (42) may be directly connected to the first flow path portion (71) of the plate structure (50, 60). The following describes the modification.

[0124] As shown in FIG. 21 , one end (42B) of the heat transfer tube (42) has the same structure as the connecting pipe (80). The one end (42B) of the heat transfer tube (42) includes a first portion (421) and a second portion (422) connected to the first portion (421). The tip of the first portion (421) is inserted into the plate structure (50, 60) through an opening (71a) of the plate structure (50, 60) and joined to the plate structure (50, 60) by, for example, burner brazing. The first portion (421) is connected to the second portion (422) outside the plate structure (50, 60). The first refrigerant flow path (42A) includes a first piping flow path portion (42A1) formed in the first portion (421) and a second piping flow path portion (42A2) formed in the second portion (422). The first piping flow path portion (42A1) and the second piping flow path portion (42A2) each extend along the stacking direction (F). The first portion (421) is connected to the first flow path portion (71) of the plate structure (50, 60), so that the first piping flow path portion (42A1) communicates with the first flow path portion (71). The first piping flow path portion (42A1) communicates with the second piping flow path portion (42A2) outside the plate structure (50, 60). The flow path area of ​​the second portion (422) is smaller than the flow path area of ​​the first portion (421). The flow path area of ​​the second portion (422) is the area of ​​a cross section of the second piping flow path portion (42A2) perpendicular to the direction in which the second piping flow path portion (42A2) extends (the stacking direction (F)). The flow path area of ​​the first portion (421) is the area of ​​a cross section of the first piping flow path portion (42A1) perpendicular to the extending direction (stacking direction (F)) of the first piping flow path portion (42A1). The one end portion (42B) of the heat transfer tube (42) is a second example of a pipe. The first portion (81, 421) is connected to the second portion (82, 422) between the fin (41) and the plate structure (50, 60). The first piping flow path portion (83a, 42A1) is connected to the second piping flow path portion (83b, 42A2) between the fin (41) and the plate structure (50, 60). This reduces the flow velocity of the refrigerant flowing through the pipe (80, 42B) toward the first flow path portion (71) of the plate structure (50, 60) between the fin (41) and the plate structure (50, 60).

[0125] With the above-described configuration, the flow path area increases when the refrigerant is sent from the second piping flow path (42A2) formed in the second portion (422) to the first piping flow path (42A1) formed in the first portion (421), thereby reducing the flow rate of the refrigerant. As a result, the refrigerant with a reduced flow rate can be sent from the first piping flow path (42A1) to the first flow path (71) of the plate structure (50, 60), thereby reducing the pressure loss of the refrigerant occurring in the plate structure (50, 60).

[0126] The structure described in "(9) Other Embodiments" above may also be employed in the modified example shown in FIG.

[0127] The outdoor heat exchanger (22) may have the same structure as the indoor heat exchanger (40) shown in "(6) Connection structure between heat transfer tube and plate structure" or "(10) Modifications" above. The outdoor heat exchanger (22) may have the same structure as the indoor heat exchanger (40) shown in "(9) Other embodiments" above.

[0128] Although the embodiments and modifications have been described above, it will be understood that various modifications in 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 combined or substituted as appropriate as long as the functionality of the subject matter of the present disclosure is not impaired.

[0129] The above-mentioned descriptions such as "first," "second," "third," etc. are used to distinguish the words to which these descriptions are attached, and do not limit the number or order of the words.

[0130] INDUSTRIAL APPLICABILITY As described above, the present disclosure is useful for heat exchangers and air conditioners.

[0131] 10 Air conditioning device 40 Indoor heat exchanger 40A Front heat exchange section 40B Rear heat exchange section 41 Fin 42 Heat transfer tube 42A First refrigerant flow path 42B One end (piping) 50 Front plate structure 51 Second refrigerant flow path 60 Rear plate structure 71 First flow path section 80 Connecting piping (piping) 81 First section 82 Second section 421 First section 422 Second section

Claims

1. A heat exchanger comprising: a heat exchange section (40A, 40B) having fins (41) and heat transfer tubes (42) having a first refrigerant flow path (42A) formed therein; and a plate structure (50, 60) directly or indirectly connected to the heat transfer tubes (42) and having a second refrigerant flow path (51) formed therein, wherein the second refrigerant flow path (51) includes a first flow path portion (71) communicating with the outside of the plate structure (50, 60), and a pipe (80, 42B) connecting the first refrigerant flow path (42A) and the second refrigerant flow path (51) includes a first portion (81, 421) and a second portion (82, 422) continuing to the first portion (81, 421) and having a flow path area smaller than that of the first portion (81, 421), and the first portion (81, 421) is connected to the first flow path portion (71).

2. The heat exchanger according to claim 1, wherein the pipe (80, 42B) is a part of the heat transfer tube (42) or a separate member from the heat transfer tube (42).

3. A heat exchanger according to claim 1 or 2, wherein the first portion (81, 421) is connected to the second portion (82, 422) outside the plate structure (50, 60).

4. A heat exchanger as described in any one of claims 1 to 3, wherein the second refrigerant flow path (51) includes a second flow path portion (72) communicating with the first flow path portion (71), and the flow path area of the first portion (81, 421) is larger than the flow path area of the second flow path portion (72).

5. A heat exchanger as described in claim 4, wherein the diameter of a circle having the same area as the cross-sectional area of the second flow path portion (72) perpendicular to the direction (G) in which the second flow path portion (72) extends is 1.5 mm or more.

6. A heat exchanger according to any one of claims 1 to 5, wherein the plate structure (50, 60) includes a plurality of plates (521, 522, 523, 524, 525, 621, 622, 623, 624, 625) stacked along the direction (F) in which the first flow path portion (71) extends, and wherein a dimension (N) of each of the plurality of plates (521, 522, 523, 524, 525, 621, 622, 623, 624, 625) in the direction (F) in which the first flow path portion (71) extends is 5 mm or less.

7. The heat exchanger according to claim 4 or 5, wherein the plate structure (50, 60) includes a plurality of plates (521, 522, 523, 524, 525, 621, 622, 623, 624, 625) stacked along the direction (F) in which the first flow path portion (71) extends, the second flow path portion (72) extends along a direction (G) perpendicular to the direction (F) in which the first flow path portion (71) extends, and a dimension (L1) of the second flow path portion (72) in a direction (H) perpendicular to the direction (F) in which the first flow path portion (71) extends and the direction (G) in which the second flow path portion (72) extends is equal to or greater than a dimension (L2) of the second flow path portion (72) in the direction (F) in which the first flow path portion (71) extends.

8. A heat exchanger as described in any one of claims 1 to 7, wherein the second refrigerant flow path (51) includes a second flow path portion (72) communicating with the first flow path portion (71), and the flow path area of the first flow path portion (71) is larger than the flow path area of a portion of the second flow path portion (72) located closer to the point of communication with the first flow path portion (71).

9. A heat exchanger as described in any one of claims 1 to 8, wherein the first refrigerant flow path (42A) of the heat transfer tube (42) and the second refrigerant flow path (51) are connected via a third refrigerant flow path (83) formed inside the connecting pipe (80) which is the pipe (80).

10. A heat exchanger according to claim 9, wherein the dimension of the first portion (81) is greater than the dimension of the second portion (82) in the extending direction (F) of the pipe (80).

11. A heat exchanger according to claim 10, wherein the second portion (82) of the connecting pipe (80) is connected to the heat transfer pipe (42), and the flow path area of the heat transfer pipe (42) is equal to or greater than the flow path area of the second portion (82).

12. A heat exchanger as described in any one of claims 1 to 11, wherein the second refrigerant flow path (51) includes a second flow path portion (72) communicating with the first flow path portion (71) and has a shape that is bent at a communication point between the first flow path portion (71) and the second flow path portion (72), and a chamfered portion is provided on an inner portion (70a) of the bent portion (70) of the second refrigerant flow path (51), or a fillet portion is provided on an outer portion (70b) of the bent portion (70) of the second refrigerant flow path (51).

13. A heat exchanger as described in any one of claims 1 to 12, wherein the first flow path portion (71) includes a first portion (71b) and a second portion (71c) located on the farther side of the plate structure (50, 60) than the first portion (71b), and a central axis (71b1) of the first portion (71b) and a central axis (71c1) of the second portion (71c) are eccentric to each other.

14. A heat exchanger according to any one of claims 1 to 13, wherein a brazing material spot (R) is provided at a connection point between the plate structure (50, 60) and the pipe (80, 42B).

15. The heat exchanger according to any one of claims 1 to 14, wherein X represents a row pitch of the plurality of pipes (80, 42B), Y represents a row pitch of the plurality of pipes (80, 42B), and Z represents an outer diameter of the first portion (81, 421), and X, Y, and Z satisfy the following condition: Z<√{(1 / 4)X ２ +Y ２ ｢ 16. A heat exchanger as described in any one of claims 1 to 15, wherein the second refrigerant flow path (51) includes a second flow path portion (72) connected to the first flow path portion (71), and a corner portion (72b) of the second flow path portion (72) is curved when viewed from the direction (G) in which the second flow path portion (72) extends.

17. An air conditioning system comprising a heat exchanger according to any one of claims 1 to 16.

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