Heat exchanger

Abstract

[Problem] To provide a heat exchanger capable of protecting an inner fin. [Solution] A heat exchanger 1 is provided with: a plurality of flat tubes 3, each having a pair of long surface parts 3A that face each other and forming a flow path that extends in an axial direction; an inner fin 4 provided inside each of the flat tubes 3; a header plate 5 having a plurality of insertion holes 6 through which axial opening end parts of the plurality of flat tubes 3 are disposed; and a reinforcement member 10 extending between the pair of long surface parts 3A at the opening end parts of the plurality of flat tubes 3. An axial outer end 4A of the inner fin 4, when viewed from a radial direction of the insertion holes 6 orthogonal to the axial direction, is disposed side by side with inner peripheral surfaces 6A of the insertion holes 6. The reinforcement member 10 is disposed, on the opening end side relative to the inner fin 4, side by side with the inner peripheral surfaces 6A of the insertion holes 6 when viewed from the radial direction. An end surface S1 of the reinforcement member 10 facing away from the opening end part is positioned closer to the opening end part than an edge part S2 of the insertion holes of the header plate 5 facing away from the opening end part.

Description

heat exchanger

[0001] The present invention relates to a heat exchanger having inner fins inside flat tubes.

[0002] Patent Document 1 discloses an EGR cooler that includes a plurality of flat tubes arranged in a row, inner fins provided inside each flat tube, and a header plate through which both ends of each flat tube are fixed. The outer ends of the inner fins are aligned horizontally with the inner circumferential surfaces of the header plate insertion holes through which the flat tubes pass (the joints between the flat tubes and the header plate), thereby enhancing the durability of the flat tubes against internal pressure, vibration, thermal expansion, and the like. Furthermore, the inner fins are positioned over substantially the entire axial area of ​​the flat tubes, in other words, the entire effective cooling range of the heat exchanger core, thereby enhancing exhaust gas cooling performance.

[0003] Also known is a heat exchanger (charge air cooler) that includes a plurality of flat tubes, inner fins, a header plate, and reinforcing members disposed at the ends of at least some of the flat tubes (see Patent Document 2). The reinforcing members have two reinforcing portions that are inserted into the flat tubes and mainly reinforce the short sides of the flat tubes.

[0004] Patent No. 4164799 Patent No. 4811258

[0005] Generally, the header plate is made of a metal material that is thicker than the flat tubes and inner fins and has a large heat capacity. The outer ends of the inner fins described in Patent Document 1 are aligned with the joints between the flat tubes and the header plate, and therefore tend to be heated by the header plate during welding or when the EGR cooler is in use, resulting in high temperatures. Furthermore, large thermal stress acts on the joints between the inner fins and the flat tubes, which can lead to buckling or cracking of the inner fins. Furthermore, when the EGR cooler is in use, the header plate repeatedly expands and contracts due to heat, which crushes and stretches the inner fins (flat tubes), further promoting cracking of the inner fins. As cracks in the inner fins progress, the flat tubes lose the durability-enhancing effect of the inner fins, and cracks can occur along the long sides of the flat tubes. In other words, buckling or cracking of the inner fins can reduce the durability of the flat tubes.

[0006] The reinforcing member of the heat exchanger (charge air cooler) described in Patent Document 2 is structured to mainly reinforce the short sides of the flat tubes, and therefore is not sufficient to reinforce the header plate against thermal expansion and contraction. Furthermore, with the reinforcing member described above, inner fins cannot be provided in the range where the two reinforcing portions are inserted, so the inner fins are shortened in the axial direction. This narrows the effective cooling range of the heat exchanger core, potentially reducing gas cooling performance. As described above, reinforcing members with a structure in which two reinforcing portions are inserted into the flat tubes are used in heat exchangers (charge air coolers), and the reinforcing member provided in the heat exchanger (charge air cooler) could not simply be used for the flat tubes of the EGR cooler described above.

[0007] SUMMARY OF THE INVENTION In consideration of the above circumstances, the present invention provides a heat exchanger capable of protecting inner fins.

[0008] The heat exchanger of the present invention includes a plurality of flat tubes (3) each having a pair of long surface portions (3A) opposed to each other and a pair of short surface portions (3B) connecting both ends of the pair of long surface portions (3A) and forming a flow path extending in an axial direction, an inner fin (4) provided inside each of the flat tubes (3), a header plate (5) having a plurality of insertion holes (6) through which open ends of the plurality of flat tubes (3) in the axial direction pass, and at least one reinforcing member (10, 11, 12) installed between the pair of long surface portions (3A) at the open end of at least one of the plurality of flat tubes (3). , wherein an outer end (4A) of the inner fin (4) in the axial direction is arranged side by side with an inner peripheral surface (6A) of the insertion hole (6) when viewed from a radial direction of the insertion hole (6) perpendicular to the axial direction, at least a part of the reinforcing member (10, 11, 12) is arranged side by side with the inner peripheral surface (6A) of the insertion hole (6) on the opening end side of the inner fin (4) when viewed from the radial direction, and an end face (S1) of the reinforcing member (10, 11, 12) facing the opposite side to the opening end is located closer to the opening end than an edge of the insertion hole of the header plate (5) facing the opposite side to the opening end.

[0009] In this case, the plurality of flat tubes (3) are arranged at intervals along the short side direction in which the short surface portions (3B) extend, and the reinforcing members (10, 11, 12) are preferably provided on at least the flat tubes (3) that are located outermost in the short side direction among the plurality of flat tubes (3).

[0010] In this case, the reinforcing member (11) may be formed with a through hole (22) that communicates with the inside of the flat tube (3).

[0011] In this case, it is preferable that a plurality of the reinforcing members (10, 11, 12) are provided on at least one of the plurality of flat tubes (3).

[0012] In this case, the plurality of flat tubes (3) are arranged at intervals along the short side direction in which the short surface portions (3B) extend, and the reinforcing member (12) is preferably installed across the plurality of flat tubes (3) adjacent to each other in the short side direction.

[0013] According to the present invention, the inner fins can be protected.

[0014] Fig. 1 is a perspective view showing a portion of a heat exchanger according to an embodiment of the present invention; Fig. 2 is a cross-sectional view showing a portion of a heat exchanger according to an embodiment of the present invention; Fig. 3 is a perspective view showing a portion of a heat exchanger according to a first modified example of an embodiment of the present invention; Fig. 4 is a perspective view showing a portion of a heat exchanger according to a second modified example of an embodiment of the present invention; Fig. 5 is a perspective view showing a portion of a heat exchanger according to a third modified example of an embodiment of the present invention;

[0015] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. Note that the X-axis, Y-axis, and Z-axis shown in the drawings are perpendicular to one another. Terms indicating directions and positions are used in this specification, but these terms are used for convenience of explanation and do not limit the technical scope of the present invention. Furthermore, an example of the "axial direction" described in the claims is the Z-axis direction, and an example of the "radial direction of the insertion hole perpendicular to the axial direction" is the X-axis or Y-axis direction.

[0016] [Heat Exchanger] A heat exchanger 1 will be described with reference to Figures 1 and 2. Figure 1 is a perspective view showing a part of the heat exchanger 1. Figure 2 is a cross-sectional view showing a part of the heat exchanger 1.

[0017] The heat exchanger 1 is, for example, an EGR (Exhaust Gas Recirculation) cooler, which cools a portion of gas exhausted from an internal combustion engine (recirculated gas) in order to return the gas to the combustion chamber. The heat exchanger 1 includes a core 2 including a plurality of flat tubes 3 and a casing (not shown) that covers the outer periphery of the core 2 with a small gap therebetween. The recirculated gas is cooled by flowing through the interior (flow passage) of the flat tubes 3. Both ends of the casing in the Z-axis direction (axial or longitudinal direction) are liquid-tightly fixed to header plates 5 (details of which will be described later), and cooling water inlet and outlet portions (not shown) are provided on the side of the casing.

[0018] As shown in Fig. 1, the core 2 of the heat exchanger 1 includes a plurality of flat tubes 3, a plurality of inner fins 4 (see Fig. 2), and a header plate 5. Note that Fig. 1 and other figures show one side of the heat exchanger 1 (core 2) in the Z-axis direction, and the present specification will focus on one side of the heat exchanger 1 in the Z-axis direction. Furthermore, because the plurality of flat tubes 3 each have approximately the same shape, the present specification will mainly focus on one flat tube 3. For the same reason, the present specification will mainly focus on one inner fin 4 and one header plate 5.

[0019] <Flat Tubes> The flat tubes 3 are arranged in a row at approximately equal intervals along the X-axis direction (the direction of the short sides of the short sides 3B). The flat tubes 3 are made of a metal material and formed into a cylindrical shape that is long in the Z-axis direction (axial direction). A flow path extending in the Z-axis direction (axial direction) is formed inside the flat tubes 3 to allow the recirculation gas to circulate. The flat tubes 3 have a cross section that is elongated in the Y-axis direction and is approximately elliptical (approximately rectangular). More specifically, the flat tube 3 has a pair of long sides 3A that face each other approximately parallel to the X-axis direction, and a pair of approximately semi-cylindrical short sides 3B that connect both edges of the pair of long sides 3A.

[0020] <Inner Fins> As shown in Fig. 2, a plurality of inner fins 4 are provided inside (in the flow paths of) a plurality of flat tubes 3. The inner fins 4 are formed, for example, from a metal material that is thinner than the flat tubes 3, and are joined (brazed) to the inner circumferential surfaces of the flat tubes 3. The inner fins 4 provided inside the flat tubes 3 are processed, for example, into a corrugated shape. Note that the shape of the inner fins 4 described above is merely an example and can be freely changed.

[0021] <Header Plate> The header plate 5 is formed, for example, in a generally plate-like shape from a metal material that is thicker than the flat tubes 3. The header plate 5 is formed with a plurality of insertion holes 6 that pass through the open ends of the flat tubes 3 in the Z-axis direction (axial direction). Each insertion hole 6 is a generally elliptical (roughly rectangular) opening that is elongated in the Y-axis direction, and the multiple insertion holes 6 are arranged in a row at generally equal intervals in the X-axis direction.

[0022] As shown in FIG. 2 , the open ends (outer ends) of the flat tubes 3 in the Z-axis direction pass through the insertion holes 6 and protrude outward (upward in FIG. 2 ) beyond the surface (outer surface) of the header plate 5. The outer ends of the flat tubes 3 are joined (brazed) to the inner circumferential surfaces 6A of the insertion holes 6. The inner fins 4 are shorter in the Z-axis direction than the flat tubes 3 and are contained within the flat tubes 3. When viewed from the X-axis direction (or Y-axis direction), the outer ends 4A of the inner fins 4 in the Z-axis direction are arranged side by side (opposite) to the inner circumferential surfaces 6A of the insertion holes 6 across the thickness of the flat tubes 3. That is, the outer ends 4A of the inner fins 4 extend from the inside (center) to the outside (from bottom to top in FIG. 2 ) in the Z-axis direction, halfway into the insertion holes 6, and are arranged side by side with the joints between the flat tubes 3 and the header plate 5. This configuration enhances the durability of the flat tubes 3. Furthermore, since the inner fins 4 are disposed over substantially the entire area of ​​the flat tubes 3 in the Z-axis direction, in other words, over the entire effective cooling range of the core 2 of the heat exchanger 1, the cooling performance of the recirculated gas can be improved.

[0023] The header plate 5 is thicker than the flat tubes 3 and inner fins 4 and has a larger heat capacity. Furthermore, the outer ends 4A of the inner fins 4 in the Z-axis direction are aligned with the joints between the flat tubes 3 and the header plate 5. Therefore, they tend to receive heat from the header plate 5 and become hot when the header plate 5 is welded (brazed) to a case or tank (not shown) or when the heat exchanger 1 is in use. Furthermore, the peripheral portions of the flat tubes 3 at the outermost ends of the header plate 5 are close to the joints between the header plate 5 and the case, and therefore tend to become hot during welding. Furthermore, large thermal stress acts on the joints between the inner fins 4 and the flat tubes 3, which can cause the inner fins 4 to buckle or crack. Furthermore, when the heat exchanger 1 is in use, the header plate 5 repeatedly expands and contracts due to heat, crushing and stretching the inner fins 4 (flat tubes 3), which exacerbates cracks in the inner fins 4. As cracks in the inner fins 4 progress, the flat tubes 3 must withstand thermal expansion and contraction (thermal stress) with the strength of their own plate thickness, and cracks may occur near the centers of the long surface portions 3A of the flat tubes 3. In other words, buckling and cracks in the inner fins 4 may reduce the durability of the flat tubes 3.

[0024] In order to prevent buckling and cracking of the inner fins 4, reinforcing members are sometimes inserted into the flat tubes 3. However, because the inner fins 4 cannot be provided within the area of ​​the flat tubes 3 where the reinforcing members are inserted, the inner fins 4 are shortened in the Z-axis (axial) direction. This narrows the effective cooling area of ​​the core 2 of the heat exchanger 1, potentially reducing the cooling performance of the recirculated gas. Therefore, the heat exchanger 1 according to this embodiment includes reinforcing members 10 that prevent buckling and cracking of the inner fins 4 while preventing a decrease in the cooling performance of the recirculated gas.

[0025] <Reinforcing Member> As shown in Fig. 1, the reinforcing member 10 is made of a metal material and has a substantially rectangular parallelepiped shape (a substantially rectangular flat plate shape). The reinforcing member 10 has a fitting portion 20 that fits between a pair of long surface portions 3A of the flat tubes 3, and a pair of joining surfaces 21 that are both ends of the fitting portion 20 in the X-axis direction. The reinforcing member 10 is joined (brazed) to (the inner peripheral surface of) one of the flat tubes 3 that is located at one end (outermost) in the X-axis direction (short side direction) of the multiple flat tubes 3. Note that Fig. 1 shows the reinforcing member 10 before joining (brazing).

[0026] As shown in FIG. 2 , the reinforcing member 10 is disposed between a pair of long surface portions 3A at the open end (outer end in the Z-axis direction) of the flat tube 3. Specifically, the reinforcing member 10 is fitted into the flat tube 3 from its outer end in the Z-axis direction, approximately at the center of the flat tube 3 in the Y-axis direction. A pair of joining surfaces 21 are brazed to the inner surfaces of the pair of long surface portions 3A of the flat tube 3. The outer end surface of the reinforcing member 10 in the Z-axis direction approximately coincides with the outer end of the flat tube 3 in the Z-axis direction. The outer end surface of the reinforcing member 10 in the Z-axis direction may protrude outward from the outer end of the flat tube 3 in the Z-axis direction or may be recessed inward (toward the center) (neither is shown). The joining position of the reinforcing member 10 is not limited to approximately the center of the flat tube 3 in the Y-axis direction and may be changed as appropriate, taking into account the range of occurrence of cracks, etc. in the inner fin 4. The width of the reinforcing member 10 in the Y-axis direction may also be changed as appropriate, taking into account the range of occurrence of cracks, etc. in the inner fin 4.

[0027] As shown in Fig. 2 , a portion of the reinforcing member 10 (a pair of joint surfaces 21) is located outside the inner fin 4 in the Z axis direction (upper side in Fig. 2 ), and is arranged side by side (facing) the inner circumferential surface 6A of the insertion hole 6 across the thickness of the flat tube 3 when viewed from the X axis direction (or Y axis direction). That is, a portion of the reinforcing member 10 on the central side in the Z axis direction (lower side in Fig. 2 ) extends partway into the insertion hole 6 from the outside to the inside in the Z axis direction (from upper side to lower side in Fig. 2 ), and is arranged side by side with the joint portion between the flat tube 3 and the header plate 5. An end face S1 of the reinforcing member 10 facing the central side in the Z axis direction (the opposite side from the opening end (lower side in Fig. 2 )) is located outside in the Z axis direction (closer to the opening end (upper side in Fig. 2 )) of an edge S2 of the insertion hole 6 of the header plate 5 facing the central side in the Z axis direction. In this embodiment, the end face S1 of the reinforcing member 10 contacts the outer end 4A of the inner fin 4 in the Z-axis direction at approximately the center of the thickness of the header plate 5. Note that a portion of the outer side of the reinforcing member 10 in the Z-axis direction is not aligned horizontally with the inner circumferential surface 6A of the insertion hole 6 (the joint portion between the flat tube 3 and the header plate 5) when viewed from the X-axis direction (or the Y-axis direction).

[0028] In the heat exchanger 1 according to the present embodiment described above, the outer ends 4A of the inner fins 4 in the Z-axis direction are aligned with the inner circumferential surfaces 6A of the insertion holes 6 as viewed in the X-axis direction, etc. The reinforcing members 10 are bridged between the pair of long surfaces 3A at the open ends of the flat tubes 3 and are aligned with the inner circumferential surfaces 6A of the insertion holes 6 as viewed in the X-axis direction, etc., outside the inner fins 4 in the Z-axis direction (closer to the open ends). This configuration reduces thermal stress acting on the joints between the inner fins 4 and the flat tubes 3, thereby suppressing buckling and cracking of the inner fins 4 during welding (brazing) and use of the heat exchanger 1. Furthermore, the reinforcing members 10 reduce thermal expansion and contraction of the header plate 5 during use of the heat exchanger 1, thereby suppressing the progression of cracks in the inner fins 4. This protects the inner fins 4 and improves the durability of the flat tubes 3. Furthermore, since the inner fins 4 are arranged over substantially the entire area of ​​the flat tubes 3 in the Z-axis direction, in other words, over the entire effective cooling range of the core 2 of the heat exchanger 1, a decrease in the cooling performance of the exhaust gas can be suppressed.

[0029] [Modifications] Various modifications of the heat exchanger 1 according to this embodiment will be described below. In the descriptions of the various modifications, the same or corresponding components as those of the heat exchanger 1 according to this embodiment will be denoted by the same reference numerals, and descriptions thereof will be omitted.

[0030] <First Modification> In the heat exchanger 1 according to the present embodiment described above, the reinforcing member 10 is formed in a substantially rectangular parallelepiped shape (a substantially rectangular flat plate shape). Therefore, depending on the size (dimension in the Y-axis direction) of the reinforcing member 10, there is a risk that the flow of recirculation gas inside the flat tubes 3 (flow passage) may be obstructed. Therefore, as shown in FIG. 3 , the reinforcing member 11 of the heat exchanger 1 according to the first modification is formed with a through-hole 22 that communicates with the inside (flow passage) of the flat tubes 3. The through-hole 22 is, for example, a substantially rectangular opening formed in the fitting portion 20. Therefore, the reinforcing member 11 (fitting portion 20) is formed in a substantially rectangular cylindrical shape overall. The fitting portion 20 of the reinforcing member 11 is provided with a pair of fitting restriction portions 23 that contact the outer ends of the pair of long surface portions 3A of the flat tubes 3 in the Z-axis direction to restrict entry into the flat tubes 3. The outer end surface of the reinforcing member 11 (fitting portion 20) in the Z-axis direction protrudes outward from the outer end of the flat tube 3 in the Z-axis direction by an amount equal to the thickness of the fitting restriction portions 23. The pair of fitting restriction portions 23 may be omitted.

[0031] According to the reinforcing member 11 of the first modification, the recirculated gas flowing through the interior (flow path) of the flat tube 3 can pass through the through holes 22, thereby preventing the reinforcing member 11 from impeding the flow of the recirculated gas. This allows the cross-sectional area of ​​the interior (flow path) of the flat tube 3 to be increased, thereby reducing pressure loss, compared to the reinforcing member 10 without the through holes 22. Furthermore, since the recirculated gas can pass through the through holes 22, the flow of the recirculated gas is less likely to be disturbed, thereby preventing the recirculated gas from drifting unsteadily. The through holes 22 are not limited to rectangular holes, but may be circular, elliptical, or polygonal (not shown). Furthermore, multiple through holes 22 may open in the reinforcing member 11 (the fitting portion 20) (not shown). While the reinforcing member 11 is formed in a rectangular ring shape when viewed in the Z-axis direction, this is not limiting. For example, the reinforcing member 11 may be formed in a generally U-shape, A-shape, or Z(S)-shape when viewed in the Z-axis direction (all of which are not shown).

[0032] <Second Modification> In the heat exchanger 1 according to the present embodiment (including the first modification) described above, one reinforcing member 10, 11 is provided for one flat tube 3, but the present invention is not limited to this. Although not shown, a plurality of reinforcing members 10, 11 may be provided for one flat tube 3 (second modification). In this case, as shown in FIG. 4 , a plurality (e.g., two) of reinforcing members 10 (or reinforcing members 11) may be connected and integrated in the Y-axis direction by connecting members 24. According to this configuration, the plurality of reinforcing members 10, 11 can more effectively suppress defects such as buckling and cracking of the inner fins 4, thereby improving the durability of the flat tubes 3.

[0033] <Third Modification> In the heat exchanger 1 according to the present embodiment (including the first and second modifications) described above, the reinforcing members 10 and 11 are provided on a single flat tube 3. However, the present invention is not limited to this. For example, as shown in FIG. 5 , the reinforcing member 12 of the heat exchanger 1 according to the third modification is installed across multiple (two in FIG. 5 ) flat tubes 3 adjacent in the X-axis direction (short-side direction). The reinforcing member 12 has two fitting portions 20 that fit into the interiors of the two flat tubes 3 and a bridging portion 25 that connects the two fitting portions 20. The bridging portion 25 is located on the outer ends of the flat tubes 3 in the Z-axis direction. This reinforcing member 12 reduces the number of steps (effort and time) required for installation compared to installing the reinforcing members 10 and 11 on each individual flat tube 3. The reinforcing member 12 may also be installed across three or more adjacent flat tubes 3 (not shown). Furthermore, the first to third modified examples may be applied to each other; for example, a through hole 22 may be formed in each fitting portion 20 of the reinforcing member 12, or multiple reinforcing members 12 may be provided on adjacent flat tubes 3, or multiple reinforcing members 12 may be connected in the Y-axis direction by a connecting member 24 (all of which are not shown).

[0034] In the heat exchanger 1 according to this embodiment (including the first to third modified examples, the same applies below), the end faces S1 of the reinforcing members 10 to 12 are also the end faces S1 between the fitting portion 20 and each of the joint surfaces 21, but the present invention is not limited to this. For example, each of the joint surfaces 21 may extend from both ends of the fitting portion 20 toward the center in the Z-axis direction, in which case the end faces S1 of the reinforcing members 10 to 12 become the end faces S1 of the fitting portions 20 as part of the reinforcing member 10 (not shown).

[0035] In the heat exchanger 1 according to this embodiment, the reinforcing members 10 to 12 are attached only to the flat tubes 3 located at one end in the X-axis direction, but the present invention is not limited to this. The reinforcing members 10 to 12 may be attached to the flat tubes 3 that are likely to buckle or crack, among the plurality of flat tubes 3.

[0036] Furthermore, the dimensions of each part of the heat exchanger 1 and the reinforcing members 10 to 12 according to this embodiment can be changed as appropriate.

[0037] The above-described embodiment shows one aspect of the heat exchanger according to the present invention, and the technical scope of the present invention is not limited to the above-described embodiment. The present invention may be variously changed, substituted, or modified without departing from the spirit of the technical concept, and the claims include all embodiments that may fall within the scope of the technical concept.

[0038] REFERENCE SIGNS LIST 1 Heat exchanger 3 Flat tube 3A Long surface portion 3B Short surface portion 4 Inner fin 4A Outer end (of inner fin) 5 Header plate 6 Insertion hole 6A Inner peripheral surface 10, 11, 12 Reinforcing member S1 End face (of reinforcing member) S2 Edge portion (of insertion hole) 22 Through hole

Claims

1. A device comprising: a plurality of flat tubes (3) each having a pair of long surface portions (3A) opposed to each other and a pair of short surface portions (3B) connecting both ends of the pair of long surface portions (3A) and forming an axially extending flow path; an inner fin (4) provided inside each of the flat tubes (3); a header plate (5) having a plurality of insertion holes (6) through which the axially open ends of the plurality of flat tubes (3) pass; and at least one reinforcing member (10, 11, 12) installed between the pair of long surface portions (3A) at the open end of at least one of the plurality of flat tubes (3), wherein the axial outer end (4A) of the inner fin (4) is arranged side by side with the inner peripheral surface (6A) of the insertion hole (6) when viewed from the radial direction of the insertion hole (6) perpendicular to the axial direction, a heat exchanger characterized in that at least a portion of the reinforcing member (10, 11, 12) is arranged side by side with the inner peripheral surface (6A) of the insertion hole (6) on the opening end side of the inner fin (4) when viewed from the radial direction, and an end face (S1) of the reinforcing member (10, 11, 12) facing the opposite side to the opening end is located closer to the opening end than the edge of the insertion hole of the header plate (5) facing the opposite side to the opening end.

2. A heat exchanger as described in claim 1, characterized in that the flat tubes (3) are arranged at intervals along the short side direction in which the short surface portions (3B) extend, and the reinforcing members (10, 11, 12) are provided on at least the flat tubes (3) located outermost in the short side direction among the flat tubes (3).

3. A heat exchanger according to claim 1, characterized in that the reinforcing member (11) has a through hole (22) that communicates with the inside of the flat tube (3).

4. A heat exchanger as described in any one of claims 1 to 3, characterized in that a plurality of the reinforcing members (10, 11, 12) are provided on at least one of the plurality of flat tubes (3).

5. A heat exchanger as described in any one of claims 1 to 3, characterized in that the plurality of flat tubes (3) are arranged at intervals along the short side direction in which the short surface portions (3B) extend, and the reinforcing member (12) is installed across the plurality of flat tubes (3) adjacent in the short side direction.

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