Heat exchanger and method for manufacturing the same

Abstract

The heat exchanger (1) comprises a header (11, 12) having a curved portion (16) with a curved shape, a plurality of flat tubes (22) that penetrate and are fixed to the partition walls (17) of the headers (11, 12), and fins (23) provided on the outer surfaces of the flat tubes (22), and the distance between the opposing side surfaces of adjacent flat tubes (22) in a direction along the curved shape provided in the curved portion (16) is constant over the longitudinal direction (DL) of the cross-sectional outline shape perpendicular to the extension direction (DT) of the flat tubes.

Description

[Technical Field]

[0001] The present disclosure relates to a heat exchanger formed by inserting and fixing flat tubes into through holes in a header having a curved shape, and a method for manufacturing the heat exchanger. [Background technology]

[0002] Conventional heat exchangers are mounted in a bent state in order to ensure as large a heat transfer area and front surface area as possible inside the compact housing of the target device such as an air conditioner (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-19459 Summary of the Invention [Problem to be solved by the invention]

[0004] In the conventional heat exchanger described above, a curved section is provided in the header, and flat tubes are inserted into and fixed to the openings of the curved section. The gaps between adjacent flat tubes in the curved section are narrowed in the longitudinal direction of the cross section, which is the direction of air flow. As a result, there is an increase in ventilation resistance of the air flow passing through the curved section, which causes problems such as increased airflow power and noise.

[0005] The present disclosure is intended to solve the above-mentioned problems, and aims to reduce the ventilation resistance of air flowing through the curved portion, even in a heat exchanger having a curved portion in the header. [Means for solving the problem]

[0006] The heat exchanger according to the present disclosure includes a header having a curved portion, and a heat exchanger that penetrates and is fixed to a partition wall of the header. The outer surface acts as a heat transfer surface for the gas.The present invention provides a plurality of flat tubes and fins provided on the outer surfaces of the flat tubes, and when the longitudinal direction of the cross-sectional outline shape perpendicular to the extending direction of the flat tubes is defined as the cross-sectional longitudinal direction, at least two flat tubes adjacent in a direction along the curved shape provided in the curved portion have a constant distance between the opposing side surfaces along the cross-sectional longitudinal direction. The distance between the side walls of the gas flow path formed by the opposing side surfaces is constant. This is what is done. [Effects of the Invention]

[0007] The heat exchanger of the present disclosure has the advantage that the spacing between the side walls of the gas flow path formed between the opposing side surfaces of adjacent flat tubes provided in the curved section is constant and does not narrow, thereby suppressing an increase in ventilation resistance. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a cross-sectional view of an entire housing that houses a heat exchanger according to a first embodiment. [Figure 2] 1 is a perspective view of a heat exchanger according to a first embodiment. [Figure 3] FIG. 2 is a top view of a header used in the first embodiment. [Figure 4] 10 is a cross-sectional view of the header used in the first embodiment taken along the line UU. FIG. [Figure 5] 10 is a top view of the header used in the first embodiment in a state before a bending process. FIG. [Figure 6] 1 is a front view of a heat transfer section of a heat exchanger according to a first embodiment. [Figure 7] 2 is a cross-sectional view taken along the line WW of the flat tube used in the first embodiment. FIG. [Figure 8] 1 is a cross-sectional view of a main part of a heat exchanger taken along the line WW in FIG. [Figure 9] FIG. 10 is a front view of a heat transfer portion of a heat exchanger showing a first modified example of the first embodiment. [Figure 10] FIG. 10 is a top view of a fin used in a first modified example of the first embodiment. [Figure 11]10 is a cross-sectional view of a main part of a heat exchanger taken along cross section VV, showing a first modified example of the first embodiment. FIG. [Figure 12] 10 is a cross-sectional view of a main part of a heat exchanger taken along cross section VV, showing a second modified example of the first embodiment. FIG. [Figure 13] 10 is a cross-sectional view of a main part of a heat exchanger taken along cross section VV, showing a third modified example of the first embodiment. FIG. [Figure 14] 10 is a front view of a main part of a bending portion 16 of a heat exchanger according to a fourth modified example of the first embodiment before the bending step. FIG. [Figure 15] FIG. 10 is a top view showing a temporary assembly of a heat exchanger according to a fourth modified example of the first embodiment. [Figure 16] FIG. 10 is a top view of a header used in a fourth modified example of the first embodiment in a state before a bending process. [Figure 17] FIG. 10 is a top view of a header used in a fourth modified example of the first embodiment. [Figure 18] FIG. 10 is a cross-sectional view of a main part of a temporary assembly of a heat exchanger taken along cross section XX, showing a fourth modified example of the first embodiment. [Figure 19] FIG. 10 is a front view of a main part of a heat exchanger showing a fourth modified example of the first embodiment. [Figure 20] FIG. 10 is a top view of a header used in a fifth modified example of the first embodiment. [Figure 21] 13 is a cross-sectional view taken along line ZZ of a header used in a fifth modified example of the first embodiment. FIG. [Figure 22] 10 is a cross-sectional view of a main part of a heat exchanger taken along line ZZ, showing a fifth modified example of the first embodiment. FIG. [Figure 23] FIG. 10 is a perspective view of a protrusion-forming member used in a fifth modified example of the first embodiment. [Figure 24] 10 is a perspective view of a main part of a flat tube and a protrusion-forming member used in a fifth modified example of the first embodiment. FIG. [Figure 25] 10 is a top view of a flat tube and a protrusion-forming member used in a fifth modified example of the first embodiment. FIG. [Figure 26] FIG. 10 is a perspective view of an L-shaped plate material used for the protrusion-forming member in a fifth modified example of the first embodiment. [Figure 27] 10 is a cross-sectional view of a main part at cross section ZZ when a flat tube is inserted into a header of a heat exchanger showing a fifth modified example of the first embodiment. FIG. [Figure 28] 3 is a flowchart showing a method for manufacturing the heat exchanger according to the first embodiment. [Figure 29] 1 is a top view showing a temporary assembly in the method for manufacturing a heat exchanger according to the first embodiment. FIG. [Figure 30] 10 is a flowchart showing a first modified example of the method for manufacturing the heat exchanger according to the first embodiment. [Figure 31] 10 is a flowchart showing a second modified example of the method for manufacturing the heat exchanger according to the first embodiment. [Figure 32] FIG. 10 is a top view showing a temporary assembly in a second modified example of the method for manufacturing the heat exchanger according to the first embodiment. [Figure 33] 10 is a flowchart showing a third modified example of the method for manufacturing the heat exchanger according to the first embodiment. [Figure 34] FIG. 10 is a cross-sectional view taken along the line VV of the header used in the second embodiment. [Figure 35] 10 is a cross-sectional view taken along the line VV of a first modified example of the header used in the second embodiment. FIG. [Figure 36] FIG. 10 is a cross-sectional view taken along the line VV of a second modified example of the header used in the second embodiment. [Figure 37] FIG. 10 is a top view of a header used in a second modified example of the second embodiment. [Figure 38] 10 is a cross-sectional view taken along line Y-Y of a header used in a second modified example of the second embodiment. FIG. [Figure 39] 10 is a cross-sectional view taken along the line VV of the header used in a third modified example of the second embodiment. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0009] Embodiment 1 A heat exchanger 1 according to a first embodiment will be described with reference to Figs. 1 to 8. The heat exchanger 1 of this embodiment functions as part of a refrigeration cycle. Fig. 1 is a cross-sectional view of the entire housing 2 that houses the heat exchanger 1 according to this embodiment. In this figure, the front side of the page is referred to as the upper side, the back side of the page as the lower side, the top side of the page as the right side, the bottom side of the page as the left side, the right side of the page as the front side, and the left side of the page as the rear side.

[0010] The heat exchanger 1 of this embodiment is housed in a housing 2 having a rectangular parallelepiped shape. The housing 2 is the housing of an outdoor unit installed outdoors. The outdoor unit has the function of exchanging heat between outside air and a heat medium in a refrigeration cycle. The heat exchanger 1 has an L-shaped cross section that follows two of the four sides that form the rectangular shape of the bottom of the housing 2: the short side on the left and the long side on the rear side (left side of the page). The cross section of the heat exchanger 1 has a curved portion at the corner between the part that follows the short side and the part that follows the long side of the rectangular shape of the housing 2.

[0011] The housing 2 has openings on the left and rear side surfaces facing the heat exchanger 1, and the heat exchanger 1 comes into direct contact with the outside air through these openings. The heat exchanger 1 is capable of passing gaseous air from the outside to the inside of the housing 2. The housing 2 houses a blower 3. The housing 2 has an opening on the front side surface facing the blower 3, and the blower 3 comes into direct contact with the outside air through these openings. When the blower 3 is operated, the air passes through the openings on the left and rear side surfaces facing the heat exchanger 1, the heat exchanger 1, and the blower 3, in that order. The air is then blown out from the opening on the front side surface of the housing 2 facing the blower 3 in the direction from the rear to the front of the housing 2 (to the right on the page).

[0012] The housing 2 also includes a machine room 6. The machine room 6 is separated from the above-mentioned air passage by a partition plate 5. The machine room 6 houses components necessary for the operation of the refrigeration cycle, such as a compressor and an expansion valve (not shown). The heat exchanger 1 is connected to the components necessary for the operation of the refrigeration cycle housed in the machine room 6. When the compressor in the machine room 6 is started with the blower 3 operating and the refrigeration cycle is operated, heat exchange occurs between the heat medium, which is a fluid flowing inside the heat exchanger 1, and the outside air, which is a gas flowing in contact with the outer surface of the heat exchanger 1.

[0013] When the heat exchanger 1 is operated as a condenser in the refrigeration cycle (e.g., during cooling operation), the heat medium, which is at a higher temperature than the air, is cooled by the air, changes phase from gas to liquid, and condenses while flowing inside the heat exchanger 1. When the heat exchanger 1 is operated as an evaporator in the refrigeration cycle (e.g., during heating operation), the heat medium, which is at a lower temperature than the air, is heated by the air, changes phase from liquid to gas, and evaporates while flowing inside the heat exchanger 1. When the air is cooled to a temperature below the dew point, the water vapor changes phase and condenses on the surface of the heat exchanger 1. When the air is cooled to a temperature below the dew point, the water vapor changes phase and frost forms on the surface of the heat transfer section 21. Drain water generated by condensation or melting frost flows down the outer surface of the heat exchanger 1 and reaches the drain pan 4 located below the heat exchanger 1, where it is drained.

[0014] Fig. 2 is a perspective view of a heat exchanger 1 according to the present embodiment. In this disclosure, the vertical and horizontal directions of the plane of the drawing as viewed in Fig. 2 are referred to as the vertical and horizontal directions of the heat exchanger 1, respectively, to represent the orientation of the heat exchanger 1. Furthermore, in the direction along the short side of the L-shaped cross section of the heat exchanger 1, the front side of the drawing is referred to as the front side, and the back side of the drawing is referred to as the rear side.

[0015] The heat exchanger 1 includes a first header 11, a heat transfer section 21, and a second header 12. In the present disclosure, a header refers to a component having an overall hollow, elongated rod shape and a plurality of through holes 13 that open in one direction and are arranged in a row for inserting and fixing flat tubes. The first header 11 and the second header 12 are connected to components required for the operation of the refrigeration cycle, such as a compressor, housed in the machine room 6 via piping (not shown). In this embodiment, the piping that connects the first header 11 and the second header 12 to the components housed in the machine room 6 is preferably provided on the right side of the first header 11 and the second header 12. Note that the position of the piping is not limited in the present disclosure.

[0016] The heat transfer unit 21 includes a plurality of hollow flat tubes and a plurality of fins provided on the outer surfaces of the flat tubes for thermal conduction. The flat tubes are connected to the first header 11 and the second header 12, respectively. The flat tubes extend in an extension direction DT. In this figure, the extension direction DT of the flat tubes is the up-down direction. The heat transfer medium in the refrigeration cycle can flow through the first header 11, the flat tubes, and the second header 12 in this order, or vice versa. Furthermore, by appropriately partitioning the interiors of the first header 11 and the second header 12, the heat transfer medium can be divided into a predetermined number of tubes and a path formed for the heat transfer medium to flow in a turning manner, rather than flowing parallel to all of the flat tubes. The heat transfer unit 21 has a central portion 19 at the center of the extension direction DT of the flat tubes. Here, the central portion 19 refers to the length of the flat tubes 22 in the extension direction DT, excluding both end portions where the local air flow rate is small. More specifically, the central portion 19 here refers to the central portion having a length of 80% of the length of the flat tube 22 in the extension direction DT, excluding 10% of the length of each of the two ends, assuming that the length of the portion exposed from the header is 100%.

[0017] The structure of the second header 12 will be described below to explain the technical features of the present disclosure in detail. FIG. 3 is a top view of the second header 12 of the heat exchanger 1 according to the present embodiment. The second header 12 is a hollow, rod-shaped object. In this figure, the front side of the page is referred to as the upper side, the back side as the lower side, the upper side as the right side, the lower side as the left side, the right side as the front side, and the left side as the rear side. As described above, the heat exchanger 1 has an L-shaped cross section and includes curved corners between the short and long sides. The second header 12 is located at the bottom of the heat exchanger 1 and has an L-shaped cross section and curved corners. The straight portion of the second header 12 on the short side is referred to as the first straight portion 14, the straight portion on the long side is referred to as the second straight portion 15, and the curved portion connecting the first straight portion 14 and the second straight portion 15 is referred to as the curved portion 16.

[0018] The second header 12 has a plurality of through holes 13. The through holes 13 penetrate a partition wall 17 above the second header 12, are open in one direction, vertically upward, and communicate with the hollow portion of the second header 12. Both ends of the second header 12 are closed by partition walls 17. A piping (not shown) is provided in the partition wall 17 at the right end of the second straight section 15, and communicates with components necessary for the operation of the refrigeration cycle, such as a compressor, housed in the machine room 6. However, the location of the piping connecting the second header 12 with components necessary for the operation of the refrigeration cycle, such as a compressor housed in the machine room 6, is not limited to this location.

[0019] In this disclosure, the shape of the curved portion 16 is expressed by the fact that the contour of the second header 12 of the curved portion 16 has two arc-shaped shapes. The two arc-shaped contours of the second header 12 of the curved portion 16 in the drawing are arcs with the same center of curvature O, different radii of curvature, and a central angle of 90°. The smaller of the two arcs constituting the contour of the curved portion 16 is referred to as the inner radius of curvature RI, and the larger of the two arcs constituting the contour of the curved portion 16 is referred to as the outer radius of curvature RO. The side of the arc constituting the contour of the curved portion 16 with the inner radius of curvature RI is referred to as the inner side, and the side with the outer radius of curvature RO is referred to as the outer side. The inner arc of the curved portion 16 connects to the contour on the right side of the first straight portion 14 (upper side of the drawing) and the front side of the second straight portion 15 (right side of the drawing). The arc on the outer periphery of the curved portion 16 is connected to the left contour (lower side of the drawing) of the first straight portion 14 and the rear side (left side of the drawing) of the second straight portion 15. The side closer to the center of curvature O of the curved shape of the curved portion 16 is the inner periphery side, and the side farther from it is the outer periphery side.

[0020] The arcs on the outer and inner sides that make up the contour of curved portion 16 do not have to have the same center of curvature O. However, the centers of curvature O on both the outer and inner sides are located farther away than the arc on the inner side when viewed from the outer side. Furthermore, the arcs on the outer and inner sides that make up the contour of curved portion 16 may each be a combination of multiple curves, and do not have to have a single center of curvature O.

[0021] The through holes 13 have a rectangular outline on the surface of the second header 12. More precisely, it is a rectangle with both longitudinal ends chamfered in an arc shape. The longitudinal direction of all of the through holes 13 provided in the first straight portion 14 is perpendicular to the longitudinal direction of the first straight portion 14. Furthermore, all of the through holes 13 provided in the first straight portion 14 have the same outline shape on the surface of the second header 12. Furthermore, for all of the through holes 13 provided in the first straight portion 14, the straight lines formed by the outer and inner end portions aligned in the longitudinal direction of the first straight portion 14 are parallel to the longitudinal direction of the first straight portion 14.

[0022] Similarly, the longitudinal direction of all of the through holes 13 provided in the second straight portion 15 is perpendicular to the longitudinal direction of the second straight portion 15. All of the through holes 13 provided in the second straight portion 15 have the same outline shape on the surface of the second header 12. Furthermore, all of the through holes 13 provided in the second straight portion 15 have straight lines formed by the outer and inner peripheral end portions aligned in the longitudinal direction of the second straight portion 15 that are parallel to the longitudinal direction of the second straight portion 15.

[0023] Therefore, the opposing contours of adjacent through holes 13 in the longitudinal direction are all parallel to each other in the first straight portion 14 and the second straight portion 15. Furthermore, the distances between the contours of adjacent through holes 13 in the longitudinal direction are all equal in the first straight portion 14 and the second straight portion 15.

[0024] The curved portion 16 has six through holes 13. The six through holes 13 have the same rectangular shape on the surface of the second header 12 as the through holes 13 provided in the first straight portion 14 and the second straight portion 15. Furthermore, the distances between the contours of adjacent through holes 13 in the direction along the curved shape of the curved portion 16 on the surface of the second header 12 are all equal. Furthermore, the contours of adjacent through holes 13 in the direction along the curved shape of the curved portion 16 that extend in a direction connecting the inner and outer circumferential sides of the curved portion 16 and face each other are all parallel. The center of gravity C of the shapes of the six through holes 13 of the curved portion 16 on the surface of the second header 12 is aligned on an imaginary arc-shaped curve LA that is midway between the arc-shaped contours of the inner and outer circumferential sides of the curved portion 16.

[0025] The number of through holes 13 provided in the curved portion 16 is not limited to six, and may be any number equal to or greater than two. The distances between the longitudinal contours of adjacent through holes 13 in the direction along the curved shape of the curved portion 16 do not necessarily have to be all equal. Furthermore, the arrangement of the centers of gravity C of the shapes of the through holes 13 of the curved portion 16 on the surface of the second header 12 in the direction connecting the inner and outer circumferential sides of the curved portion 16 is not limited to being aligned on an arc-shaped curve that is midway between the arc-shaped contours of the inner and outer circumferential sides.

[0026] FIG. 4 is a cross-sectional view of the second header 12 taken along cross section UU, which is a cross section perpendicular to the longitudinal direction of the second straight section 15. Cross section UU here is at the same position as cross section UU shown in FIG. 3 , and is a cross section from the right end of the second straight section 15 in FIG. 3 at a distance half the longitudinal length of the second straight section 15, and does not include the through holes 13. In this embodiment, the second header 12 includes a partition wall 17 whose cross-sectional shape at cross section UU is square. In the figure, the cross section of the partition wall 17 is indicated by hatching with diagonal lines. The cross-sectional shapes of both the outer surface and the inner surface of the partition wall 17 of the second header 12 are square. The second header 12 has a hollow space inside the inner surface of the partition wall 17. Note that the shape of the cross section perpendicular to the curved shape of the curved section 16 of the second header 12 is not limited to a square and may be, for example, a rectangle, a circle, an ellipse, a semicircle, a triangle, or a polygon.

[0027] FIG. 5 is a top view of the second header 12 before the bending process for imparting a curved shape to the curved portion 16. In the present disclosure, two methods are possible for manufacturing a heat exchanger 1 having a curved portion 16. One method for manufacturing a heat exchanger 1 having a curved portion 16 is to insert and fix flat tubes 22 into the through holes 13 of a straight header to create a flat assembly, and then impart the curved portion 16 through a bending process. The other method for manufacturing a heat exchanger 1 having a curved portion 16 is to insert and fix flat tubes 22 into a header having a curved portion 16. The figure shows a second header 12 having an overall straight shape that is formed during the manufacturing process of the heat exchanger 1 when the former of these two methods is used.

[0028] After the bending process, the length of the inner periphery of the bending portion 16 in the direction along the curved shape is reduced, and the length of the outer periphery of the bending portion 16 in the direction along the curved shape is increased. Accordingly, the shape of the upper surface of the bending portion 16 changes from a rectangle to a fan shape. In this embodiment, the longitudinal directions of the through holes 13 provided in the bending portion 16 after the bending process are all parallel. In consideration of the change in the shape of the upper surface of the bending portion 16 described above, the through holes 13 provided in the bending portion 16 before the bending process are arranged so that the distance between the outlines of adjacent through holes 13 narrows from the inner periphery side (left side of the drawing) to the outer periphery side (right side of the drawing), as shown in the figure.

[0029] 6 is a front view of a heat transfer section 21 including flat tubes 22 and fins 23 of a heat exchanger 1 showing this embodiment. The fins 23 allow air to pass through in the longitudinal direction of a cross section of the flat tubes 22 that are in contact with the fins 23, the cross section being perpendicular to the extension direction DT. The fins 23 have the function of expanding the heat transfer area on the air side of the heat exchanger 1 and promoting heat transfer between the air and the heat medium. The shape of the fins 23 is not limited, but it is desirable for the fins 23 to have a shape that can flexibly deform in response to changes in the arrangement of the flat tubes 22 that accompany changes in the arrangement of the through holes 13 during the bending process described above; a specific example is a wire mesh.

[0030] The flat tubes 22 have the same cross-sectional shape throughout the extension direction DT without any bends or twists. Because the extension direction DT of the flat tubes 22 is the up-down direction, as described above, drain water generated on the surfaces of the flat tubes 22 and fins 23 due to condensation or melting frost can be guided downward along the surface by its own weight and guided to the drain pan 4 below the heat exchanger 1. The fins 23 desirably have a structure that has the effect of promoting the flow of water droplets due to gravity and inducing capillary force in the water droplets, so as to move and guide the drain water generated on the surface to the flat tubes 22 as quickly as possible.

[0031] FIG. 7 is a cross-sectional view of the flat tube 22 used in this embodiment taken along a cross section W-W perpendicular to the extension direction DT. The cross section W-W here is at the same position as the cross section W-W shown in FIG. 6, and in FIG. 6, the cross section is at a distance half the length of the flat tube 22 in the extension direction DT from the upper end of the flat tube 22. The extension direction DT of the flat tube 22 is not shown in FIG. 7, but it is the direction from the back of the page to the front of the page. As shown in FIG. 7, the shape of the flat tube 22 in a cross section perpendicular to the extension direction DT is rectangular and has a longitudinal direction. In the present disclosure, the longitudinal direction of the shape of the flat tube 22 in a cross section perpendicular to the extension direction DT is referred to as the cross-sectional longitudinal direction DL. More strictly, the shape is rectangular with both ends of the cross-sectional longitudinal direction DL chamfered in an arc. The longitudinal directions of the two sides forming the long sides of the rectangle are both parallel to the cross-sectional longitudinal direction DL. The holes 41 formed in the cross section W-W of the flat tubes 22 are formed in a cross section perpendicular to the extension direction DT over the entire extension direction DT. Therefore, inside the heat exchanger 1, the heat medium can pass through the flow paths formed in the flat tubes 22 over the extension direction DT, with the holes 41 having a cross section shaped perpendicular to the extension direction DT.

[0032] The outer surfaces of the flat tubes 22 act as heat transfer surfaces for the air in the heat transfer section 21 of the heat exchanger 1. The cross-sectional shape of the flat tubes 22 perpendicular to the extension direction DT is rectangular, with the cross-sectional longitudinal direction DL being the direction in which air passes through the fins 23 in the shortest distance. By positioning the side of the flat tubes 22 perpendicular to the direction in which air passes in the shortest distance and arranged to obstruct the airflow as the short side of the rectangle, it is possible to prevent an increase in ventilation resistance. Furthermore, by arranging the long axis side of the rectangle so that it is aligned with the air flow direction, it is possible to ensure a heat transfer area without increasing ventilation resistance. Note that in the figure, the flat tube 22 has six holes 41 with rectangular or semicircular cross-sectional shapes, but the number and shape of the holes 41 of the flat tube 22 are not limited to those described above.

[0033] 8 is a cross-sectional view of a main part of the heat exchanger 1 of this embodiment taken along the cross section W-W, which is a transverse cross section of the central part 19 in the height direction. The cross section W-W here is located at the same position as the cross section W-W shown in FIG. 6. The main part here refers to all six flat tubes 22 in the curved part 16, the three flat tubes 22 in each of the first straight part 14 and the second straight part 15 closest to the curved part 16, and the fins 23 provided on those flat tubes 22. The outline of the second header 12 located below the cross section W-W of the heat exchanger 1 (toward the back of the page) is shown by a dashed line in the figure.

[0034] In the figure, the six flat tubes 22 in the curved portion 16, whose cross-sectional longitudinal direction DL is from the upper left to the lower right, are parallel to each other in the cross-sectional longitudinal direction DL of adjacent flat tubes 22 in the direction along the curved shape of the curved portion 16. As described above, the long sides of the rectangular outlines of the flat tubes 22 are parallel to the cross-sectional longitudinal direction DL. Therefore, the long sides of the rectangular outlines of adjacent flat tubes 22 provided in the curved portion 16 in the direction along the curved shape of the curved portion 16 are parallel to each other. In other words, the arrangement of the flat tubes 22 provided in the curved portion 16 is such that the distance between the opposing side surfaces of two adjacent flat tubes 22 in the direction along the curved shape of the curved portion 16 of the second header 12 is constant throughout the cross-sectional longitudinal direction DL.

[0035] In this way, by positioning the flat tubes 22 at the center 19 of the curved portion 16 in the extension direction DT of the flat tubes 22, the air flow path between adjacent flat tubes 22 can flow smoothly without being narrowed, thereby reducing ventilation resistance.

[0036] In addition to the features regarding the arrangement of the flat tubes 22 in the curved portion 16 described above, the heat exchanger 1 of this embodiment also has the following features regarding the arrangement and dimensions of the flat tubes 22 and fins 23 in the curved portion 16.

[0037] 8, the flat tubes 22 in the first straight portion 14 and the second straight portion 15 are provided with fins 23a, and the flat tubes 22 in the curved portion 16 are provided with fins 23b. The flat tubes 22 in the first straight portion 14 and the second straight portion 15 have a width in the cross-sectional longitudinal direction DL that is larger than the fins 23a that are provided thereon. On the other hand, the flat tubes 22 in the curved portion 16 have a width in the cross-sectional longitudinal direction DL that is smaller than the fins 23b that are provided thereon.

[0038] Therefore, the fins 23b provided on the flat tubes 22 in the curved portion 16 are wider than the fins 23a provided on the flat tubes 22 in the first straight portion 14 and the second straight portion 15. In this case, by appropriately designing the wider fins 23b, for example, by increasing the density per volume of the wider fins 23b compared to the narrower fins 23a, it is possible to equalize the airflow resistance of both fins. Specific methods for adjusting the density per volume of the fins 23 include, for example, increasing the number of wires per volume in the case of wire mesh, or increasing the number of peaks per volume in the case of corrugated fins. Note that the density per volume of the fins 23 is not limited in this disclosure. By thus equalizing the airflow resistance throughout the heat exchanger 1, it is possible to more uniformly distribute the air velocity throughout the heat exchanger 1 and reduce heat transfer loss that occurs when the heat load is uneven.

[0039] The outer peripheral ends of the flat tubes 22 in the cross-sectional longitudinal direction DL of the curved portion 16 are aligned on an arc-shaped curve that follows the curved shape of the curved portion 16. When the flat tubes 22 are arranged in this manner, if fins 23 having a width smaller than the width of the flat tubes 22 in the cross-sectional longitudinal direction DL are provided, some of the holes 41 of the flat tubes 22 will not have fins 23 on the side walls perpendicular to the cross-sectional longitudinal direction DL. In this case, for those of the holes 41 of the flat tubes 22 that have fins 23 on their side walls, the heat transfer area on the air side is enlarged, promoting heat transfer. On the other hand, for those of the holes 41 of the flat tubes 22 that do not have fins 23 on their side walls, the heat transfer area on the air side is not enlarged, so heat transfer is not promoted. Therefore, the presence or absence of fins 23 on the side walls causes an imbalance in heat flux among the holes 41 of the flat tubes 22, resulting in heat transfer loss.

[0040] In the present embodiment, the flat tubes 22 of the bending portion 16 have one end on the outer circumferential side or the inner circumferential side in the cross-sectional longitudinal direction DL arranged on an arc-shaped curve that follows the curved shape of the bending portion 16. The flat tubes 22 of the bending portion 16 are provided with fins 23b having a width greater than the width of the flat tubes 22 in the cross-sectional longitudinal direction DL. Therefore, the holes 41 of all the flat tubes 22 of the bending portion 16 are provided with fins 23b on the side walls in the direction perpendicular to the cross-sectional longitudinal direction DL.

[0041] By configuring the heat exchanger 1 in this manner, as described above, even if the line connecting the outer ends of the flat tubes 22 provided in the curved portion 16 is not a straight line, the heat flux of the holes 41 of the multiple flat tubes 22 is balanced, which has the effect of reducing heat transfer loss.

[0042] Variation 1. FIG. 9 is a front view of the heat transfer section 21 of the heat exchanger 1 illustrating this modification. Similar to the first embodiment, the heat exchanger 1 illustrating this modification has a curved portion 16 in which the spacing between the opposing side surfaces of two adjacent flat tubes 22 in the direction along the curved shape of the header is constant across the cross-sectional longitudinal direction DL. In this modification, the shape of the fins 23 is limited to corrugated fins formed by bending a thin, elongated rectangular metal plate into a corrugated shape. In the figure, the fins 23 provided between the flat tubes 22 are corrugated fins. The corrugated fins are inclined toward the point where they contact the adjacent flat tubes 22 in the extension direction of the header, and have a structure that allows drain water generated on the surface to slide down the inclination and easily flow to the flat tubes 22. This modification is identical to the first embodiment except for the shape of the fins 23.

[0043] FIG. 10 is a top view of the fin 23 used in this modification. The top view here refers to the top view of the fin 23 as viewed from the upper side of the paper (the upper side of the heat exchanger 1) in FIG. 9 . In this figure, the fin 23 is a corrugated fin and has dimensions referred to as a fin width WF and a fin height HF. The fin width WF refers to the outer dimension of the fin 23 in the direction along the cross-sectional longitudinal direction DL of the flat tubes 22 in the heat exchanger 1. The fin height HF is the same dimension as the spacing between adjacent flat tubes in the direction along the curved shape of the curved portion 16 of the second header 12 in the heat exchanger 1. The fin 23 has a fin pattern 40, which is a protrusion and an opening that control the air flow on the surface to improve heat transfer. In conventional techniques for manufacturing corrugated fins, the fin width WF, fin height HF, and fin pattern 40 are uniquely determined by the specifications of the corrugated fin manufacturing equipment.

[0044] FIG. 11 is a cross-sectional view of a main portion of a heat exchanger 1 showing this modified example, taken along the line W-W, which is a cross section at the central portion 19 of a flat tube 22. The line W-W here is the same as that shown in FIG. The main portion here refers to all six curved portions 16, as well as three flat tubes 22 each located closest to the curved portions 16 of both the first straight portion 14 and the second straight portion 15, and the fins 23 provided on those flat tubes 22. The outline of the second header 12 located below the line W-W of the heat exchanger 1 (toward the back of the page) is shown by a dashed line in the drawing.

[0045] In this figure, the fin 23 represents the cross section of a thin plate forming a corrugated fin. In this figure, the fin 23 is depicted as contacting one of the adjacent flat tubes 22 on the left side in the direction along the curved shape of the curved portion 16 of the second header 12. Here, the corrugated fin is a thin plate bent into a wave shape when viewed from the front of the heat exchanger 1. Therefore, when the cross section is scanned from the cross section W-W in the extension direction DT of the flat tubes 22, the cross section of the thin plate of the fin 23 does not necessarily contact the flat tube 22 on the left side, but is located somewhere between the flat tube 22 on the left side and the flat tube 22 on the right side. In this figure, the region where the cross section of the thin plate of the fin 23 is located in a cross section at any position in the center portion 19 of the flat tube 22 is referred to as the fin cross section appearance region AF and is represented by a rectangle surrounded by a dashed line. The width of the fin cross-section appearing area AF in the direction along the cross-section longitudinal direction DL is the fin width WF, and the width in the direction perpendicular to the cross-section longitudinal direction DL is the fin height TF.

[0046] In addition to the above-mentioned features regarding the arrangement of the flat tubes 22 in the curved portion 16 and the features regarding the arrangement and dimensions of the flat tubes 22 and fins 23 in the curved portion 16, the heat exchanger 1 of this modified example has the following features regarding the shape of the fins 23.

[0047] In this figure, all of the fins 23 provided on the flat tubes 22 in the first straight section 14, the second straight section 15, and the curved section 16, including the omitted parts, are corrugated fins, have the same fin width WF, and have the same fin height HF. Furthermore, although not shown in this figure, the fin patterns 40 of all the fins 23 are the same.

[0048] By configuring the heat exchanger 1 in this manner, the local ventilation resistance of the fins 23 becomes equal throughout the heat exchanger 1. This makes it possible to more evenly distribute the air velocity across each fin, more evenly distribute air throughout the entire heat exchanger 1, and improve heat exchange efficiency. Furthermore, it is possible to manufacture the heat exchanger 1 of this embodiment using a manufacturing device for corrugated fins of one specification, which enables resource conservation for the manufacturing device compared to when corrugated fins of multiple specifications are used.

[0049] In this figure, the flat tubes 22 are provided with fins 23 having a width greater than the width of the flat tubes 22 in the cross-sectional longitudinal direction DL so that the fins 23 are provided on the side walls perpendicular to the cross-sectional longitudinal direction DL of the holes 41 of all of the flat tubes 22 provided in the curved portion 16. This modified example does not necessarily have the features regarding the arrangement and dimensions of the flat tubes 22 and fins 23 of the curved portion 16 described here.

[0050] Variation 2. 12 is a cross-sectional view of a main part taken along the cross section W-W, which is a cross section of the central part 19 of the flat tube 22 of the heat exchanger 1 showing this modified example. The meaning of the cross section W-W and the main part here is the same as in FIG. 11. The outline of the second header 12 located below the cross section W-W of the heat exchanger 1 (toward the back of the page) is shown by a dashed line in the figure.

[0051] The heat exchanger 1 illustrating this modification includes a curved portion 16, similar to the first embodiment. The flat tubes 22 provided in the curved portion 16 are arranged such that the distance between the opposing side surfaces of two adjacent flat tubes 22 in a direction along the curved shape of the curved portion 16 of the second header 12 is constant across the cross-sectional longitudinal direction DL. This modification is the same as the first embodiment except for the arrangement of the fins 23.

[0052] The heat exchanger 1 of this modification has the following feature regarding the arrangement of the fins 23 in addition to the feature regarding the arrangement of the flat tubes 22 in the curved portion 16 described above.

[0053] In this figure, the line LF connecting the outer peripheral ends of all the fins 23 provided on the flat tubes 22 in the curved portion 16 is a straight line. The line LF is positioned on the outer peripheral side of the outer peripheral ends of all the flat tubes 22 in the curved portion 16.

[0054] The housing 2 mounting the heat exchanger 1 according to this modification is installed outdoors, with the line LF exposed toward the outside of the housing 2. Outside, a foreign object, such as a ball, may collide with the outer surface of the heat exchanger 1. If one fin 23 protrudes from the outer surface of the heat exchanger 1, when the foreign object collides with the protruding fin 23, only the protruding portion of the fin 23 comes into contact with the foreign object. Therefore, the kinetic energy of the foreign object is concentrated in the small contact area with the fin 23. The external pressure thus generated deforms the fin 23. Once the fin 23 deforms, air cannot flow through the deformed portion of the fin 23, and the heat transfer performance of the heat exchanger 1 deteriorates.

[0055] In the heat exchanger 1 according to this modification, the outer peripheral edges of the fins 23 are aligned in a straight line, which increases the contact area when a foreign object collides with the fins 23. This allows the kinetic energy of the foreign object to be dispersed and transmitted over the larger contact area with the fins 23. This reduces external pressure and suppresses deformation of the fins 23. The fins 23 according to this modification may be corrugated fins.

[0056] By configuring the heat exchanger 1 in this way, it is possible to suppress deformation of the fins 23 due to collision of foreign objects and maintain heat transfer performance in an installation environment where collision of foreign objects is possible.

[0057] Variation 3. 13 is a cross-sectional view of a main part taken along the cross section W-W, which is a cross section of the central part 19 of the flat tube 22 of the heat exchanger 1 showing this modified example. The meaning of the cross section W-W and the main part here is the same as in FIG. 11. The outline of the second header 12 located below the cross section W-W of the heat exchanger 1 (toward the back of the page) is shown by a dashed line in the figure.

[0058] The heat exchanger 1 illustrating this modification includes a curved portion 16, similar to the first embodiment. The flat tubes 22 provided in the curved portion 16 are arranged such that the distance between the opposing side surfaces of two adjacent flat tubes 22 in a direction along the curved shape of the curved portion 16 of the second header 12 is constant across the cross-sectional longitudinal direction DL. This modification is the same as the first embodiment and modification 2, except for the arrangement of the flat tubes 22.

[0059] The heat exchanger 1 of this modified example has the following features regarding the arrangement of the flat tubes 22 in addition to the features regarding the arrangement of the flat tubes 22 in the curved portion 16 described above.

[0060] In this figure, the line LT is a straight line connecting the outer peripheral ends of the flat tubes 22 of the curved portion 16. The line LT is disposed on the outer peripheral side of the outer peripheral ends of all the fins 23 provided on the flat tubes 22 of the curved portion 16.

[0061] When a foreign object collides with the outer surface of the heat exchanger 1, if one flat tube protrudes, the kinetic energy of the foreign object is transmitted intensively to the small contact area with the flat tubes 22. The external pressure thus generated deforms the flat tubes 22, reducing their strength. If the flat tubes 22 are unable to withstand the pressure of the heat medium flowing inside, the heat medium will leak to the outside, causing the heat exchanger 1 to lose its function. In the heat exchanger 1 of this modified example, the outer peripheral ends of the flat tubes 22 are aligned in a straight line, allowing for an increased number of flat tubes with which the foreign object comes into contact when it collides. Therefore, the kinetic energy of the foreign object is transmitted in a dispersed manner to the contact areas with the multiple flat tubes 22. This reduces the external pressure and makes it possible to suppress deformation of the flat tubes 22. The fins 23 of this modified example may be corrugated fins.

[0062] By configuring the heat exchanger 1 in this way, it is possible to suppress deformation of the flat tubes 22 and maintain the function of the heat exchanger 1 even in an installation environment where there is a possibility of collision with a foreign object.

[0063] Variation 4. FIG. 14 is a front view of a main part of the curved portion 16 of the heat exchanger 1 showing this modified example before the bending process. As described above, in the present disclosure, a method for manufacturing a heat exchanger 1 having a curved portion 16 includes inserting and fixing flat tubes 22 into the through holes 13 of a linear header to form a flat assembly, and then providing the curved portion 16 through the bending process. This figure is a front view of the main part of the flat assembly formed before the bending process, which is referred to as the main part, to which a curved shape is provided in the bending process. This modified example includes a twisted portion 25 having a twisted shape between the portion of the flat tube 22 inserted and fixed in the second header 12 and the end of the fin 23 of the main part shown in this figure. Except for this feature, this modified example is identical to the first modified example of the present embodiment in which the fin 23 is a corrugated fin. The twisted portion 25 is formed in a portion of the flat tube 22 closer to the end inserted into the second header 12 than the end of the central portion 19 in the extension direction DT.

[0064] 15 is a top view showing a temporary assembly 30 in the manufacturing method of the heat exchanger 1 showing this modified example. In the figure, the temporary assembly 30 is placed on a horizontal stage ST so that its flat plate shape is laid horizontally. The direction from the front to the back of the page is vertically downward. This figure shows a top view in this orientation.

[0065] In the above-described manufacturing method, the temporary assembly 30 of the heat transfer section 21, in which the flat tubes 22 are inserted and fixed into the through holes 13 of the second header 12 before the bending process, has an arrangement in which the flat tubes 22 and the fins 23 are arranged alternately. A commonly used method for fastening the flat tubes 22 to the header is to braze them together using a continuous furnace. Another commonly used method for fastening the flat tubes 22 to the header in a heat-transfer-compatible manner is to braze them together simultaneously with brazing them to the header. For this joining method, a commonly used technique is to use a continuous furnace with a mechanism for introducing the assembly into the furnace using a conveyor. The internal atmosphere of the continuous furnace is replaced with nitrogen from air to prevent oxide films from forming on the surfaces of the metals used to make the heat exchanger 1 components, which would impede the brazing process. Therefore, to conserve resources in the manufacturing process, it is necessary to minimize the tunnel-shaped internal space of the continuous furnace to reduce the amount of nitrogen required. By forming the temporary assembly 30 in a flat plate shape, it is possible to reduce the height of the tunnel-shaped internal space of the continuous furnace, thereby making the internal space smaller.

[0066] In this figure, the flat tubes 22 and fins 23 of the temporary assembly 30 are not yet bonded together before heating in the continuous furnace. By fixing the fins 23 to the flat tubes 22 of the temporary assembly 30 and simultaneously inserting all of the flat tubes 22 into the through holes 13 of the header, it is possible to shorten the time required for the manufacturing process of the heat exchanger 1. To fix the flat tubes 22 and fins 23 together, restraining jigs 31 are placed on both ends of the temporary assembly 30 in a direction perpendicular to the extension direction DT of the flat tubes 22 so as to extend along the extension direction DT of the flat tubes 22. Two wire-shaped fixing restraining jigs 33 extending in a direction perpendicular to the extension direction DT of the flat tubes 22 are then wrapped around the entire member sandwiched between the two restraining jigs 31, and the flat tubes 22 and fins 23 are fixed together by the tension of the fixing restraining jigs 33.

[0067] In the temporary assembly 30, fins 23 are not provided between the flat tubes 22 inserted into the first straight section 14 and the second straight section 15 that are adjacent to the curved section 16, and between the flat tubes 22 inserted into the curved section 16 that are adjacent to the first straight section 14 and the second straight section 15. A jig called a buffer section 32 is placed in these sections. The restraining jig 31, the buffer section 32, and the fixing restraining jig 33 are made of a material that is different from the heat exchanger 1 and has a higher melting point than the material of the heat exchanger 1, and are not bonded to the flat tubes 22 or fins 23 that come into contact with them by heating in a continuous furnace. After heating in a continuous furnace, the restraining jig 31, the buffer section 32, and the fixing restraining jig 33 can be easily detached from the assembly. The curved section 16 is molded using the assembly after the restraining jig 31, the buffer section 32, and the fixing restraining jig 33 have been detached.

[0068] As described above, the through holes 13 provided in the curved portion 16 of the second header 12 before the bending process are arranged so that the spacing between the contours of adjacent through holes 13 narrows from the inner periphery to the outer periphery, taking into account the change in the shape of the upper surface of the curved portion 16 from rectangular to fan-shaped during the bending process. Therefore, in the temporary assembly 30, the flat tubes 22 inserted into the through holes 13 of the curved portion 16 arranged as described above are required to be arranged so that the spacing between the contours of adjacent tubes narrows from the inner periphery to the outer periphery. On the other hand, corrugated fins are elongated, rectangular metal sheets with folds extending perpendicular to the extension direction DT of the flat tubes 22. Twisting these folds results in plastic deformation, which increases ventilation resistance at the deformed locations. To avoid this increase in ventilation resistance, when the fins 23 are corrugated fins, the cross-sectional shape of the flat tubes 22 perpendicular to the extension direction DT is fixed to a rectangle. Therefore, in the temporary assembly 30, in the portion where the fins 23 are provided, the intervals between the contours of adjacent flat tubes 22 are required to be constant and parallel.

[0069] Therefore, the flat tubes 22 inserted into and fixed in the curved portion 16 of the second header 12 are provided with twisted portions 25 having a twisted shape between the portions inserted into the header and the ends of the fins 23. The flat tubes 22 in the curved portion 16 have a constant distance between the contours of adjacent tubes in the portion of the extension direction DT where the fins 23 are provided. Then, from the portion where the fins 23 are provided to the end inserted into the through hole 13 via the twisted portions 25, the flat tubes 22 in the curved portion 16 are arranged so that the distance between the contours of adjacent tubes narrows from the inner periphery to the outer periphery.

[0070] After the bending process, the flat tubes 22 having the twisted portions 25 have a constant distance between the contours of adjacent portions inserted into the header, making them parallel. Therefore, in the bending process, while the header is given the curved shape of the curved portion 16, a process is required in which the twisted portion 25 is twisted in the direction opposite to the twisting direction of the twisted portion 25 to return the twisted portion 25 to a straight shape. At this time, since the twisted portion 25 is plastically deformed, it does not assume the same straight shape as the other flat tubes 22 that do not have the twisted portion 25, and traces of the plastic deformation remain. In the present disclosure, these traces of plastic deformation are also referred to as the twisted portion 25.

[0071] In the heat exchanger 1 of this modified example, the longitudinal directions of the cross-sectional shapes of the through holes 13 in the curved portion 16 of the second header 12, taken in a cross section perpendicular to the opening direction, may change before and after the bending process so that adjacent through holes are no longer parallel to each other. The arrangement of the through holes 13 in the second header 12 before and after the bending process is illustrated in FIGS. 16 and 17 . The through holes 13 in the curved portion 16 shown in FIG. 17 are arranged radially from the center of curvature O, such that the longitudinal directions of the cross-sectional shapes of adjacent through holes are no longer parallel to each other. In this case, in the temporary assembly 30, none of the flat tubes 22 have twisted portions 25 formed therein, and the cross-sectional longitudinal directions DL are parallel to each other. After the curved portion 16 is inserted into and fixed in the straight, uncurved second header 12, twisted portions 25 are formed in the flat tubes 22 in the curved portion 16 simultaneously with the bending process of forming the curved portion 16. As a result, the part inserted into and fixed to the second header 12 has the cross-sectional longitudinal direction DL arranged radially around the center of curvature O, and the central part 19 where the fins 23 are provided is parallel to adjacent ones in the direction along the curved shape of the curved part 16 of the header.

[0072] By configuring the heat exchanger 1 in this manner, it is possible to reduce the ventilation resistance of the heat transfer section 21 provided in the curved section 16. This configuration is particularly effective in a heat exchanger 1 in which the flat tubes 22 of the plate-shaped heat transfer section 21 are inserted into a straight header, brazed together in a continuous furnace, and then the header is given a curved shape to form the curved section 16.

[0073] In addition to the above-mentioned features regarding the arrangement of the flat tubes 22 in the curved portion 16 and the features regarding the twisting of the flat tubes 22 in the curved portion 16, the heat exchanger 1 of this modified example has the following features regarding the length of the twisted portion 25.

[0074] In FIG. 15, there are six flat tubes 22 in the curved portion 16. FIG. 18 is a cross-sectional view of these six flat tubes 22 at cross section XX, which is a cross section perpendicular to the extension direction of the six flat tubes 22. Cross section XX here refers to the same cross section XX in FIG. 15. Also, in FIG. 18, dashed lines represent the contours of the flat tubes 22 in a cross section perpendicular to the extension direction of the flat tubes 22 at the end inserted into the second header 12. In the figure, the angle formed by the central portion 19 of the flat tube 22 in the extension direction DT and the longitudinal direction DL of the cross section of the portion joined to the header is defined as the torsion angle RT. Of the six flat tubes 22, the two central flat tubes 22, which are the third and fourth from the left, have an extremely small torsion angle RT between the central portion 19 in the extension direction DT and their end portions. Of the six flat tubes 22, the two flat tubes 22 at both ends, the first and sixth from the left, have a larger torsion angle RT between the central portion 19 in the extension direction DT and the end portion compared to the other flat tubes 22. Furthermore, of the six flat tubes 22, the two flat tubes 22 at the second and fifth from the left have a torsion angle RT between the central portion 19 in the extension direction DT and the end portion that is between the central and end flat tubes 22.

[0075] 14 , attention is focused on the six flat tubes 22 in the curved portion 16. The central flat tube 22, which has a small torsion angle RT, has an extremely small distance between its end closest to the twisted portion 25 of the fin 23 and its portion joined to the second header 12. In addition, the flat tubes 22 at both ends, which have large torsion angles RT, have a larger distance between their end closest to the twisted portion 25 of the fin 23 and its portion joined to the second header 12 than the other flat tubes 22 in the curved portion 16. The second and fifth flat tubes 22 from the left, which have torsion angles RT between those at both ends and the central one, have a distance between their end closest to the twisted portion 25 of the fin 23 and its portion joined to the second header 12 that is between those at both ends and the central one.

[0076] That is, the distance between the end of the fin 23 provided on the flat tube 22 having the twisted portion 25 that is closest to the twisted portion 25 and the portion joined to the header increases in the order of the twist angle RT.

[0077] By configuring the heat exchanger 1 in this manner, the deformation of the flat tubes 22 at the twisted portion 25 does not interfere with the fins 23 in the curved portion 16. Therefore, the fins 23 do not deform in the cross-sectional longitudinal direction DL, making it possible to reduce the ventilation resistance of the heat transfer portion 21 provided in the curved portion 16. This is particularly effective in a heat exchanger 1 in which the flat tubes 22 of the plate-shaped heat transfer portion 21 are inserted into a straight header, fixed by brazing in a continuous furnace, and then a curved shape is imparted to the header to form the curved portion 16.

[0078] Furthermore, in addition to the features regarding the arrangement of the flat tubes 22 in the curved portion 16, the features regarding the twist of the flat tubes 22 in the curved portion 16, and the features regarding the length of the twisted portion 25, the heat exchanger 1 of this modified example has the following features regarding the air shielding member 26 provided in the twisted portion 25.

[0079] FIG. 19 is a front view of a main portion of a heat exchanger 1 illustrating this modified example. The main portion here refers to the portion of the flat tubes 22 in the curved portion 16 that is inserted into and fixed to the second header 12. In the figure, an air shielding member 26 is provided between the fins 23 provided on the flat tubes 22 in the curved portion 16 and the second header 12. The air shielding member 26 has a ventilation resistance equivalent to or greater than that of the fins 23. Without the air shielding member 26, the end of the curved portion 16 closer to the second header 12 in the extension direction DT of the fins 23 and the portion without the fins 23 provided between the end and the second header 12 have significantly lower ventilation resistance than the central portion 19 with the fins 23. Therefore, air passing through the curved portion 16 flows selectively and concentrates in the portion of the flat tubes 22 without the fins 23 that is closer to the second header 12. This reduces the air flow rate to the portion where the fins 23 are provided and heat transfer is promoted, resulting in a wind speed distribution that reduces the overall heat transfer efficiency. As shown in the figure, by providing an air blocking member 26 between the second header 12 and the fins 23, it is possible to prevent the wind speed distribution described above from being induced.

[0080] When the temperature of the heat medium in the heat exchanger 1 is lower than the dew point of the air, condensation occurs on the surface of the heat exchanger 1. If the air shielding member 26 is installed below the heat exchanger 1, the condensation formed on the surface of the heat exchanger 1 will turn into drain water and be supplied to the air shielding member 26. If the drain water is prevented from being discharged by the air shielding member 26, the drain water remaining above the air shielding member 26 will increase the ventilation resistance in this area. Therefore, it is desirable for the air shielding member 26 to have the function of quickly draining the drain water by promoting the flow down of water droplets due to gravity and inducing capillary force in the water droplets. Specific examples include wire mesh, open-cell foam metal, and a molded resin product with a drain water flow path inside.

[0081] By configuring the heat exchanger 1 in this manner, it is possible to improve the air velocity distribution in the heat transfer section 21 provided in the curved section 16 and maintain the efficiency of heat transfer. This is particularly effective in a heat exchanger 1 in which the components of the flat heat transfer section 21 are brazed together in a continuous furnace, and then the header is given a curved shape to form the curved section 16, and a larger gap is provided between the end of the fins 23 and the header than for the other flat tubes 22.

[0082] Variation 5. The heat exchanger 1 illustrating this modification includes a curved portion 16, similar to the first embodiment. The flat tubes 22 provided in the curved portion 16 are arranged such that the distance between the opposing side surfaces of two adjacent flat tubes 22 in a direction along the curved shape of the curved portion 16 of the second header 12 is constant across the cross-sectional longitudinal direction DL. This modification is the same as the first embodiment except for the features related to the structure of the header, which will be described later. FIG. 20 is a top view of the second header 12 used in the heat exchanger 1 showing this modified example.

[0083] The heat exchanger 1 of this modified example has the following features regarding the structure of the header, in addition to the features regarding the arrangement of the flat tubes 22 in the curved portion 16 described above.

[0084] As described above, in the present disclosure, a method for manufacturing a heat exchanger 1 having a curved portion 16 includes inserting and fixing flat tubes 22 into a header having the curved portion 16. The heat exchanger 1 illustrating this modified example is manufactured using this method. The following method is also available for manufacturing a header having a curved portion 16. First, a header is created that has a linear shape entirely in the direction following the curved shape of the curved portion 16 and has a plurality of through holes 13 on its top surface that are aligned in the direction following the curved shape of the curved portion 16. Then, the header is bent so that all of the plurality of through holes 13 on its top surface open upward, thereby forming the curved portion 16.

[0085] When a linear header is curved, the inner periphery of the curved portion 16 shrinks in length in the direction along the curved shape of the curved portion 16, while the outer periphery expands in length in the direction along the curved shape of the curved portion 16. Accordingly, the shape of the upper surface of the curved portion 16 changes from rectangular to fan-shaped. Here, the shape of the through hole 13 provided in the upper surface of the curved portion 16 is rectangular with long sides in a direction perpendicular to the direction along the curved shape of the curved portion 16 and short sides in a direction along the curved shape of the curved portion 16. Therefore, before and after the formation of the curved portion 16, the shape of the through hole 13 is changed so that the length of the short side on the inner periphery side becomes shorter and the length of the short side on the outer periphery side becomes longer.

[0086] The heat exchanger 1 illustrating this modified example includes a manufacturing step of inserting the flat tubes 22 of the heat transfer section 21 into the through holes 13 of the header having the curved portions 16 manufactured as described above. When the flat tubes 22 are inserted from the opening direction of the through holes 13, it is desirable that the shape of the through holes 13 of the header be a shape obtained by expanding the outline shape of the flat tubes 22 to be inserted at equal intervals. If the gap between the outline of the flat tube 22 and the through holes 13 is too narrow, insertion becomes difficult; if the gap is too wide, it becomes difficult to completely fill the gap formed between the flat tube 22 and the through holes 13 after insertion and join them.

[0087] In this modification, the flat tubes 22 inserted into the first straight portion 14 and the second straight portion 15 and the flat tubes 22 inserted into the curved portion 16 have the same cross-sectional shape perpendicular to the extension direction DT. In this case, it is desirable that the shapes of the through holes 13 formed in the second header 12 are also the same. However, because the through holes 13 of the curved portion 16 deform as described above, it becomes difficult to insert the flat tubes 22 into the short sides on the inner circumferential side, which deforms to shorten the length. Therefore, in this modification, as shown in FIG. 20 , the second header 12 has cutout portions 18 on the side surfaces on the outer circumferential side of the curved portion 16, which have a shape that is continuous with the through holes 13 on the upper surface. The cutout portions 18 of the second header 12 enable the flat tubes 22 to be inserted into the through holes 13 of the curved portion 16 from a direction perpendicular to the opening direction of the through holes 13.

[0088] In the drawing, the width of the cutout portion 18 in the direction along the curved shape of the curved portion 16 is the same as that of the through hole 13, and the cutout portion 18 has a shape that is continuous with the through hole 13. The short side on the outer periphery of the through hole 13 is integrated with the space of the cutout portion 18 and disappears as an outline. In other words, the through hole 13 provided in the second header 12 has a shape that is continuous with the cutout portion 18 provided in the side surface of the second header 12 located on the outer periphery side in the longitudinal direction in a cross section perpendicular to the opening direction. Note that, although all the through holes 13 in the drawing have a shape that is continuous with the cutout portion 18 of the through hole 13 here, it is sufficient that at least the through holes 13 provided in the curved portion 16 have this shape.

[0089] In the drawing, the short side on the outer periphery side of the through hole 13 is indicated by a dashed line. The outline of the inner surface side of the partition wall 17 on the side surface on the outer periphery side of the second header 12 is exposed above the cutout portion 18. In the drawing, the outline of the inner surface side of the partition wall 17 on the side surface on the outer periphery side of the second header 12 is indicated by a solid line.

[0090] FIG. 21 is a cross-sectional view of the second header 12 used in this modification, taken along a cross section ZZ perpendicular to the curved shape of the curved portion 16. In this figure, the cross section ZZ is the same as the cross section ZZ shown in FIG. 20 and includes the through hole 13. At the cross section ZZ, the second header 12 has square cross-sectional shapes on both its outer and inner surfaces. A hollow space is formed inside the square inner surface. The second header 12 has a through hole 13 on its upper surface that communicates with the hollow space. In the figure, the second header 12 has a cutout 18 at the corner formed by the left side surface and the upper surface. The through hole 13 and the cutout 18, the outlines of which are not actually visible, are indicated by dashed lines in the figure. The lower end of the cutout 18 is located below the lower end of the through hole 13. The lower end of the through hole 13 here refers to the inner surface of the bulkhead 17, which forms the upper surface of the second header 12 having the through hole 13. It should be noted that the shape of the cross section perpendicular to the extending direction of the header in this modified example is not limited to a square.

[0091] FIG. 22 is a cross-sectional view of the curved portion 16 of the heat exchanger 1 showing this embodiment at cross section ZZ perpendicular to the direction along the curved shape of the curved portion 16 of the second header 12. Cross section ZZ is the same as cross section ZZ shown in FIG. 20 and is a cross section including the through hole 13. In this figure, the flat tubes 22 are inserted into the through hole 13. Furthermore, the convex portion 27 provided on the flat tube 22 is inserted into the cutout portion 18. The second header 12, the flat tubes 22, and the convex portion 27 are joined at their mutually contacting interfaces. At cross section ZZ, the heat medium sealed inside the second header 12 can pass only through the holes 41 of the flat tubes 22.

[0092] 23 is a perspective view showing a protrusion-forming member 28 used in this embodiment, which forms a protrusion 27 on the flat tube 22. The protrusion-forming member 28 includes a protrusion 27 and a winding portion 29. The protrusion 27 has a shape that closes the cutout portion 18 provided in the second header 12 when the flat tube 22 is inserted into the through hole 13. The protrusion 27 is joined to the cutout portion 18 when the flat tube 22 is inserted into the through hole 13.

[0093] In the figure, the protrusion 27 has an overall rectangular parallelepiped shape. The width of the protrusion 27 in the left-right direction is slightly smaller than the width of the cutout 18 in the direction along the curved shape of the curved portion 16 of the second header 12, and is a dimension that allows the protrusion 27 to fit into the cutout 18 with an appropriate gap. The height of the protrusion 27 in the up-down direction is greater than the thickness of the upper wall of the second header 12. The width of the protrusion 27 in the depth direction, which is perpendicular to the left-right and up-down directions, is greater than the thickness of the partition wall 17 on the outer peripheral side of the second header 12. The winding portion 29 of the protrusion-forming member 28 has a shape in which two rod-shaped portions bifurcated in the left-right direction extend with their longitudinal direction in the depth direction of the protrusion 27 on the far side of the drawing in the depth direction of the protrusion 27. The longitudinal length of the winding portion 29 is slightly longer than the width of the flat tube 22 in the cross-sectional longitudinal direction DL. The width in the left-right direction of the rod-shaped portion of winding portion 29 is half the width in the left-right direction of protrusion 27. The height in the up-down direction of the rod-shaped portion of winding portion 29 is equal to the width in the left-right direction of the rod-shaped portion of winding portion 29 and is smaller than the height in the up-down direction of protrusion 27.

[0094] FIG. 24 is a perspective view of essential parts of the flat tubes 22 and the protrusion-forming member 28 used in this modified example. The essential parts here refer to the end of the flat tube 22 that is inserted into the through hole 13 of the second header 12. In the figure, the winding portion 29 of the protrusion-forming member 28 has a bifurcated base portion where the protrusion 27 is provided, which contacts one end of the flat tube 22 in the cross-sectional longitudinal direction DL. Opposing surfaces of the two rod-shaped portions of the winding portion 29 contact the outer shell of the flat tube 22, and the longitudinal direction extends along the cross-sectional longitudinal direction DL. The end of the winding portion 29 on the side that does not have the protrusion 27 in the extending direction is bent so that the opposing surfaces of the two rod-shaped portions are on the inner circumferential side, so as to follow the contour of the end of the flat tube 22 on the side that does not contact the protrusion 27. In this way, by processing the winding portion 29 to cause plastic deformation, the frictional force applied to the contact area between the winding portion 29 and the flat tube 22 makes it possible to fix the protrusion forming member 28 to the flat tube 22.

[0095] 25 is a top view of the flat tube 22 and the protrusion-forming member 28 used in this modification. In the figure, the winding portion 29 of the protrusion-forming member 28 has a rod-shaped portion in contact with the contour of the flat tube 22 on both opposing surfaces.

[0096] FIG. 26 is a perspective view of an L-shaped plate 45 used in this modification as the material for the protrusion-forming member 28. The L-shaped plate 45 is made by punching a plate having the same thickness as the width of the protrusion-forming member 28 in the left-right direction into an L shape with the short and long sides joined perpendicularly at one end. The L-shaped plate 45 has a short side 42, a long side 43, and a notch 44. The short side 42 constitutes the protrusion 27 of the protrusion-forming member 28. The long side 43 is formed with a notch 44 in the longitudinal direction to halve the thickness of the plate, and the long side 43 is then split into two to form the wrapping portion 29 of the protrusion-forming member 28. The L-shaped plate 45 can be produced in a short time using press working.

[0097] FIG. 27 is a cross-sectional view of a main portion of the curved portion 16 taken along a cross section ZZ perpendicular to the direction along the curved shape of the curved portion 16 of the second header 12 when the flat tubes 22 are inserted into the second header 12 of the heat exchanger 1 according to the present embodiment. The main portion here refers to the periphery of the through hole 13 of the curved portion 16 of the second header 12. In this figure, the cross section ZZ is the same as the cross section ZZ shown in FIG. 20 and includes the through hole 13. In this figure, the insertion process of inserting the flat tubes 22 into the through hole 13 of the second header 12 is shown over time in the order of (a), (b), and (c). During the insertion process, the flat tubes 22 move laterally from the outer circumferential side (left side of the drawing) of the second header 12 toward the inner circumferential side (right side of the drawing) of the second header 12, following the longitudinal direction of the cross-sectional shape of the through hole 13 on the top surface of the second header 12. Thereafter, the flat tubes 22 are fixed, and the second header 12 is moved vertically in the up-down direction, which is the extension direction DT of the flat tubes 22, to complete the insertion process.

[0098] First, the flat tubes 22 are arranged so that the ends thereof to be inserted into the through holes 13 are on the outer periphery of the second header 12, above the lower ends of the cutouts 18, and below the lower ends of the through holes 13. The flat tubes 22 are then positioned in a direction along the curved shape of the curved portions 16 of the second header 12 so that the short sides of the cross-sectional shape perpendicular to the extension direction DT fit within the width of the cutouts 18 in the direction along the curved shape of the curved portions 16 of the second header 12. The flat tubes 22 are then inserted so as to move laterally along the cutouts 18 from the short sides of the cross-sectional shape perpendicular to the extension direction DT. The positional relationship between the second header 12 and the flat tubes 22 during this lateral movement is shown in FIG. 27( a). This lateral movement continues until one end of the flat tube 22 in the cross-sectional longitudinal direction DL, which does not have the convex portion 27, comes into contact with the inner short side of the cross-sectional shape of the second header 12, which is perpendicular to the opening direction of the through hole 13. Figure 27(b) shows the positional relationship between the second header 12 and the flat tubes 22 when the lateral movement is complete. When the lateral movement is complete, the second header 12 is moved vertically upward on the page, in the extension direction DT of the flat tubes 22. This vertical movement continues until the lower surface of the convex portion 27 comes into contact with the lower end of the cutout portion 18. Figure 27(c) shows the positional relationship between the second header 12 and the flat tubes 22 when the vertical movement is complete.

[0099] As described above, in a header in which a straight-shaped header is curved to form a curved portion 16, the shape of the cross section perpendicular to the opening direction of the through hole 13 is deformed. The deformation of the through hole 13 at the curved portion 16 causes the dimension of the inner header to shrink in the direction along the curved shape of the curved portion 16 and the outer header to expand in the direction along the curved shape of the curved portion 16. In this modification, the width of the curved second header 12 at the outer peripheral side of the through hole 13 and the outer peripheral end of the cutout 18 in the direction along the curved shape of the curved portion 16 is wider than before bending, making it easier to insert the flat tube 22 by lateral movement from the outer peripheral side into the cutout 18 and the through hole 13. Furthermore, during the lateral movement, the flat tube 22 is guided by the end faces of the partition walls 17 on both sides in the direction along the curved shape of the cutout 18 and the through hole 13, which extend in the longitudinal direction of the shape in the cross section perpendicular to the opening direction. Therefore, although the width of the inner peripheral end of the through hole 13 is smaller than before bending, it can easily move horizontally until it comes into contact with this portion. Then, during the vertical movement, the convex portion 27 moves along the side surface of the cutout portion 18 and the through hole 13 until the lower surface of the convex portion 27 comes into contact with the lower end of the cutout portion 18, thereby making it possible to bring the flat tubes 22 and the convex portion 27 into appropriate contact with the second header 12 to facilitate joining.

[0100] By configuring the header and flat tubes 22 of the heat exchanger 1 in this manner, the flat tubes 22 of the heat transfer section 21 can be inserted reliably, and the yield of the heat exchanger 1 in the manufacturing process can be increased. This is particularly effective for a heat exchanger 1 having through holes 13 in the curved section 16 that are deformed when the header is curved.

[0101] Note that the method of providing the flat tube 22 with the protrusion 27 that covers the cutout 18 of the header is just one example, and is not limited to the method of using a protrusion forming member 28 having a winding portion 29.

[0102] Hereinafter, methods for manufacturing the heat exchanger 1 according to the first embodiment and the first to fifth modifications of the first embodiment will be described.

[0103] The method for manufacturing the heat exchanger 1 according to the first embodiment and the first to third modifications of the first embodiment is as follows: a header fabrication process for fabricating a linear header in which a plurality of through holes are provided in the partition wall so that the distance between adjacent through holes at both ends in the longitudinal direction of a cross section perpendicular to the opening direction includes a distance between adjacent through holes that is smaller at one end than at the other end; a temporary assembly process for preparing a temporary assembly of a heat transfer section including a plurality of flat tubes having a cross-sectional longitudinal direction DL that is the longitudinal direction of a cross-sectional outline shape perpendicular to the extension direction, and a plurality of fins; an insertion step of inserting the flat tube of the temporary assembly prepared in the temporary assembly step into the through hole of the header; a joining step of joining the contacting portions of the through holes and the flat tubes formed in the insertion step to form a flat plate-like assembly; a bending process in which a curved shape is imparted to the header of the assembly produced in the joining process, such that the side of the through holes at both ends in the longitudinal direction where the spacing between adjacent through holes is narrower is positioned on the outer periphery, and curved portions 16 are formed in the flat tubes adjacent in the direction along the curved shape so that the spacing between the opposing side surfaces is constant across the cross-sectional longitudinal direction DL; It has the following characteristics.

[0104] 28 is a flowchart showing a method for manufacturing a heat exchanger 1 according to the first embodiment and the first to third modifications of the first embodiment. The manufacturing method here includes a header fabrication step S1, a temporary assembly step S2, an insertion step S3, a joining step S4, and a bending step S5. The header fabrication step S1 and the temporary assembly step S2 can be performed simultaneously in parallel.

[0105] The header creation process S1 is a process for creating a header by forming a plurality of through holes 13 arranged in the direction of extension of the header in a hollow rod-shaped object, the through holes 13 being capable of passing through and fixing flat tubes 22 to the upper surface of the object, as shown in Fig. 5. Fig. 5 shows the shape of the second header 12 in a process prior to the bending process S5. Therefore, although the curved portion 16 is not given a curved shape, it will be referred to as the curved portion 16 in Fig. 5 and in the description herein.

[0106] In the second header 12, the multiple through holes 13 have the same shape. They are arranged at equal intervals in the direction in which the second header 12 extends, and the longitudinal direction of a cross section perpendicular to the opening direction is perpendicular to the direction in which the second header 12 extends. Furthermore, they are provided so that one end of the longitudinal direction of the cross section perpendicular to the opening direction is aligned along the direction in which the second header 12 extends. However, in this manufacturing method, the longitudinal direction of the through holes 13 formed in the curved portion 16 is not perpendicular to the direction in which the second header 12 extends. Furthermore, the distance between adjacent through holes 13 formed in the curved portion 16 in the direction in which the second header 12 extends is smaller at one end (the upper end in the figure) of the longitudinal direction of the cross section perpendicular to the opening direction than at the other end (the lower end in the figure). Furthermore, the spacing between adjacent through holes 13 formed in the portion that becomes the curved portion 16 in the direction in which the second header 12 extends is equal to the spacing between adjacent through holes 13 provided in portions other than the curved portion 16 at the longitudinal center of the cross section perpendicular to the opening direction.

[0107] The header creation process S1 may also be a process of forming a plurality of through holes 13 arranged in the longitudinal direction in a rectangular plate-shaped member that forms the upper surface, and attaching a partition member that forms a hollow space communicating with the through holes 13 to the lower surface of this rectangular plate-shaped member.

[0108] FIG. 29 shows a temporary assembly 30 in the manufacturing method of the heat exchanger 1 here, with FIG. 29(a) being a top view and FIG. 29(b) being a side view. In FIG. 29(b), the holes 41 of the flat tubes 22 are not shown. The temporary assembly step S2 is a step of arranging the flat tubes 22 and the fins 23 alternately on a horizontally placed stage ST, as shown in FIG. 29, to create a temporary assembly 30. At this time, the cross-sectional longitudinal direction DL of the flat tubes 22 is the up-down direction (the direction from the front side to the back side of the page). In the figure, the flat tubes 22 inserted into the through holes 13 of the curved portion 16 of the second header 12 of the temporary assembly 30 are arranged so that the distance between adjacent tubes with fins 23 interposed between them is smaller at one end of the cross-sectional longitudinal direction DL than at the other end. This arrangement is to match the arrangement of the through holes 13 of the header, and the spacing at one end (one end on the lower side of the paper in Figure 29(b)) in the cross-sectional longitudinal direction DL is smaller than the spacing at the other end (one end on the upper side of the paper in Figure 29(b)). Therefore, in Figure 29, the flat tubes 22 of the temporary assembly 30 sandwiched between two buffer sections 32 have an arrangement in which the cross-sectional longitudinal direction DL is not parallel. The stage ST may be equipped with either or both of a structure and a mechanism for fixing the flat tubes 22 and fins 23 of the temporary assembly 30 in a desired arrangement.

[0109] The flat tubes 22 and the fins 23 of the temporary assembly 30 do not need to be joined. However, they must be fixed together within the temporary assembly 30 to prevent separation during the insertion step S3. Here, a method for fixing the flat tubes 22 and the fins 23 of the temporary assembly 30 will be described. First, square-pipe-shaped restraining jigs 31 are placed on both ends of the temporary assembly 30 in a direction perpendicular to the extension direction DT of the flat tubes 22 (left-right direction in the figure) so as to extend along the extension direction DT of the flat tubes 22. Then, two wire-shaped fixing restraining jigs 33 extending in a direction perpendicular to the extension direction DT of the flat tubes 22 are wrapped around the entire member sandwiched between the two restraining jigs 31. In this way, the flat tubes 22 and the fins 23 are fixed together by the tension of the fixing restraining jigs 33. The method of fixing the flat tubes 22 and fins 23 of the temporary assembly 30 in the temporary assembly process S2 is not limited to the above-mentioned method, and for example, the flat tubes 22 and fins 23 may be partially bonded with an adhesive.

[0110] The insertion process S3 involves inserting the flat tubes 22 of the heat transfer section 21 created in the temporary assembly process S2 into the header created in the header creation process S1. In this example, the insertion process S3 includes the following procedure. First, the cross-sectional shape of the upper surface of the multiple through holes 13 of the header is aligned with the cross-sectional shape perpendicular to the extension direction DT of the multiple flat tubes 22 of the temporary assembly 30 fixed on the stage ST. Then, the opening direction of the through holes 13 of the header is aligned with the extension direction DT of the flat tubes 22 of the temporary assembly 30. Then, the header is moved from one end of the flat tubes 22 toward the center 19 in the opening direction of the through holes 13 of the header. Through the above procedure, the insertion process S3 involves simultaneously inserting all of the flat tubes 22 of the temporary assembly 30 into the through holes 13 of the header. Note that the stage ST may have either or both of a structure and a mechanism that allows the flat tubes 22 to be smoothly inserted into the through holes 13 of the header.

[0111] In the joining step S4, the flat tubes 22 inserted into the header of the temporary assembly 30 in the insertion step S3 are joined to the header. In this example, the joining between the header and the flat tubes 22 and between the flat tubes 22 and the fins 23 in the joining step S4 is performed by brazing using a continuous furnace. A clad material, which is a material with a brazing material attached to its surface, is suitable as the material for the header and the flat tubes 22 or the fins 23. When the brazing material on the surface of the clad material is heated to a temperature above its melting point in the continuous furnace, it melts and becomes liquid. The liquid brazing material flows into the gaps between the through holes 13 of the header and the flat tubes 22 and between the flat tubes 22 and the fins 23 due to capillary forces acting on these gaps. When the brazing material is then cooled to a temperature below its melting point, it solidifies while forming an alloy with the surrounding materials, thereby joining the header and the flat tubes 22 and the flat tubes 22 and the fins 23. After the header and the flat tubes 22 and the flat tubes 22 and the fins 23 are joined, the restraining jig 31, the buffer section 32, and the fixing restraining jig 33 are removed from the heat transfer section 21. Note that the joining step S4 is not limited to the method using the continuous furnace described above. For example, the joining step S4 may be a method in which the flat tubes 22 and the fins 23 are bonded with an adhesive having high thermal conductivity, and the through holes 13 of the header and the flat tubes 22 are joined by a method that does not use a continuous furnace, such as high-frequency brazing or torch brazing.

[0112] The bending step S5 is for imparting a curved shape to the header of the flat assembly created in the joining step S4. In this example, the bending step S5 has the following steps: First, the flat assembly in which the flat tubes 22 of the heat transfer section 21 are joined to the header is placed in a horizontal position on the stage ST. Next, a bending die having an inner curved shape of the curved section 16 on its outer surface is fixed to a predetermined position above the assembly, and a force is applied to move the header so that one end in the longitudinal direction is raised upward while pressing the header against the bending die. In this way, the portions of the header and the heat transfer section 21 that contact the bending die are molded into the inner curved shape of the curved section 16. Note that the bending step S5 is not limited to the method using the bending die described above.

[0113] In the heat transfer unit 21 after the bending step S5, the distance between the opposing side surfaces of the flat tubes 22 adjacent in the direction along the curved shape of the bending portion 16 is constant along the cross-sectional longitudinal direction DL. Before and after the bending step S5, the distance between the opposing side surfaces of two flat tubes 22 adjacent in the direction along the curved shape of the bending portion 16 in the cross-sectional longitudinal direction DL changes from being non-constant as in the temporary assembly 30 in Fig. 29 to being constant as described above. The fins 23 have a flexible structure like a wire mesh and flexibly deform in accordance with changes in the distance between the flat tubes 22 provided at both ends in the direction along the curved shape of the bending portion 16 in the cross-sectional longitudinal direction DL.

[0114] By configuring the manufacturing method for the heat exchanger 1 in this way, the assembly fed into the continuous furnace is flat, making it possible to reduce the tunnel-shaped internal space of the continuous furnace and perform brazing joints with reduced resources. Furthermore, by devising the arrangement of the through holes 13 in the header creation process S1, the spacing between adjacent flat tubes 22 in the curved portion 16 naturally becomes constant along the cross-sectional longitudinal direction DL after the bending process S5. This makes it possible to manufacture a heat exchanger 1 that reduces the ventilation resistance of the curved portion 16.

[0115] The manufacturing method for the heat exchanger 1 representing the fourth modified example of the first embodiment is a modification of the above-described manufacturing method and includes a step of providing twisted portions 25 to the flat tubes 22 of the heat transfer section 21. The manufacturing method for the heat exchanger 1 representing the fourth modified example of the first embodiment includes a first twisting step before the temporary assembly step, and a second twisting step simultaneously with the bending step. The first twisting step is for forming the twisted portions 25 in the flat tubes 22 used in the bending section 16. The second twisting step is for twisting the twisted portions 25 of the bending section 16 in a direction that reduces the torsion angle RT.

[0116] 30 is a flowchart showing a manufacturing method of the heat exchanger 1 according to the fourth modification of the first embodiment. The manufacturing method here includes a header creating step S21, a first twisting step S22, a temporary assembling step S23, an inserting step S24, a joining step S25, a bending step S26, and a second twisting step S27. The header creating step S21, the first twisting step S22, and the temporary assembling step S23 can be performed simultaneously in parallel. The bending step S26 and the second twisting step S27 are performed simultaneously.

[0117] The header creating step S21 is the same as the header creating step S1 in the manufacturing method described above. The header creating step S21 is a step of creating a header having a linear shape and in which the longitudinal directions of the shapes of the plurality of through holes 13 in the curved portion 16 on the upper surface are not parallel, as shown in FIG.

[0118] The first twisting process S22 is a process of providing a twisted portion 25 to the flat tube 22 at the curved portion 16 of the temporary assembly 30. At this time, the cross-sectional longitudinal direction DL of the flat tube 22 to which the twisted portion 25 has been provided is parallel to adjacent tubes in the central portion 19, but is not parallel to adjacent tubes in the portion inserted into the through hole 13 of the header.

[0119] FIG. 15 shows a temporary assembly 30 in the manufacturing method of the heat exchanger 1 here. FIG. 15(a) is a top view, and FIG. 15(b) is a side view. In FIG. 15(b), the holes 41 in the flat tubes 22 and the fin patterns 40 of the fins 23 are not shown. The temporary assembly step S2, as shown in FIG. 15, is a step of creating a temporary assembly 30 by arranging the flat tubes 22 and the fins 23 alternately on a horizontally placed stage ST so that the cross-sectional longitudinal direction DL of the central portions 19 of the flat tubes 22 is vertical. The portion of the temporary assembly 30 sandwiched between the two buffer portions 32 is the portion to be inserted into the curved portion 16 of the header, and this portion of the flat tubes 22 has a twisted portion 25 formed in the first twisting step S22. The stage ST may have either or both a structure and a mechanism for fixing the flat tubes 22 and fins 23 of the temporary assembly 30 in a desired arrangement.

[0120] In the insertion step S24, the flat tubes 22 of the heat transfer section 21 prepared in the temporary assembly step S23 are inserted into the header prepared in the header preparation step S21. The insertion step S24 here is the same step as the insertion step S3 in the manufacturing method described above.

[0121] The joining step S25 is for joining the flat tubes 22 inserted into the header of the temporary assembly 30 in the insertion step S24 to the header. The joining step S25 here is the same step as the joining step S4 in the manufacturing method described above.

[0122] The bending step S26 is for imparting a curved shape to the header of the flat assembly created in the joining step S25. In this bending step S26, the method for bending the header having a straight shape is the same as in the bending step S5 of the manufacturing method described above. The manufacturing method for the heat exchanger 1 here includes, simultaneously with the bending step S26 for bending the header, a second twisting step S27 for twisting the flat tubes 22 provided in the bending portion 16 and having the twisted portion 25 in a direction that reduces the torsion angle RT.

[0123] Before and after the bending step S26, the shape of the upper surface of the curved portion 16 of the second header 12 changes from the rectangular shape shown in FIG. 5 to the sector shape shown in FIG. 3. Accordingly, the arrangement of the cross-sectional longitudinal direction DL of the shape of the upper surface of the through holes 13 of the curved portion 16 changes from non-parallel as shown in FIG. 5 to parallel as shown in FIG. 3. If the flat tubes 22 of the curved portion 16 still have the twisted portions 25, adjacent tubes will be parallel to each other at the portions fixed to the through holes 13 but will no longer be parallel at the central portions 19. As a result, after the bending step S26, the opposing side surfaces of adjacent flat tubes 22 at the central portions 19 along the curved shape of the curved portion 16 will not be uniform across the cross-sectional longitudinal direction DL, resulting in increased ventilation resistance of air passing through this portion. Therefore, the manufacturing method for the heat exchanger 1 here includes a second twisting step S27, in which the twisted portions 25 are twisted so that the twist angle RT is 0°, simultaneously with the bending step S26. By the second twisting step S27, the flat tubes 22 adjacent to each other in the direction along the curved shape of the curved portion 16 have a constant distance between the opposing side surfaces at the central portion 19 along the cross-sectional longitudinal direction DL.

[0124] By configuring the manufacturing method of the heat exchanger 1 in this manner, the fins 23 provided on the flat tubes 22 of the curved portion 16 do not deform, making it possible to manufacture a heat exchanger 1 that reduces the ventilation resistance of the curved portion 16.

[0125] As a variation of the method for manufacturing heat exchanger 1 according to the fourth modification of the first embodiment, a manufacturing method shown in the flowchart of FIG. 31 can be given.

[0126] The header creation step S31 is the same step as the header creation step S1 described above. The header creation step S31 is a step of creating a header having a linear shape, as shown in FIG. 16, in which the longitudinal directions of the shape of the multiple through holes 13 on the top surface of the curved portion 16 are parallel. FIG. 16 shows the shape of the second header 12 in the step prior to the bending step S26. Therefore, although the curved portion 16 is not given a curved shape, it will be referred to as the curved portion 16 in FIG. 16 and in the description herein.

[0127] FIG. 32 shows a temporary assembly 30 in the manufacturing method of the heat exchanger 1 here. FIG. 32(a) is a top view, and FIG. 32(b) is a side view. In FIG. 32(b), the holes 41 of the flat tubes 22 are not shown. The temporary assembly step S2 is a step of creating a temporary assembly 30 by arranging the flat tubes 22 and the fins 23 alternately on a horizontally placed stage ST so that the cross-sectional longitudinal direction DL of the central portions 19 of the flat tubes 22 is vertical, as shown in FIG. 32. None of the flat tubes 22 in the temporary assembly 30 have any twists or bends. Note that the fins 23 of the temporary assembly 30 in the manufacturing method of the heat exchanger 1 here may be corrugated fins.

[0128] In the insertion step S33, the flat tubes 22 of the heat transfer section 21 prepared in the temporary assembly step S32 are inserted into the header prepared in the header preparation step S31. The insertion step S33 here is the same step as the insertion step S3 in the manufacturing method described above.

[0129] The joining step S34 is for joining the flat tubes 22 inserted into the header of the temporary assembly 30 in the insertion step S33 to the header. The joining step S34 here is a step similar to the joining step S4 in the manufacturing method described above.

[0130] The bending step S35 is for imparting a curved shape to the header of the flat assembly created in the joining step S34. In this bending step S35, the method for bending the linear header is the same as in the bending step S5 described above. The manufacturing method for the heat exchanger 1 here includes, simultaneously with the bending step S35 for bending the header, a twisting step S36 for twisting the flat tubes 22 provided in the bending portion 16 and having the twisted portion 25 in a direction that increases the torsion angle RT.

[0131] Before and after the bending step S26, the shape of the upper surface of the curved portion 16 of the second header 12 changes from the rectangular shape shown in FIG. 16 to the sector shape shown in FIG. 17. Accordingly, the arrangement of the cross-sectional longitudinal direction DL in the shape of the upper surface of the through holes 13 of the curved portion 16 changes from the parallel arrangement shown in FIG. 16 to the non-parallel arrangement shown in FIG. 17. At this time, if the flat tubes 22 provided in the curved portion 16 remain straight without being twisted, the cross-sectional longitudinal directions DL of adjacent flat tubes 22 will no longer be parallel to each other at both the portions fixed to the through holes 13 and the central portions 19. As a result, after the bending step S26, the side surfaces of adjacent flat tubes 22 in the direction along the curved shape of the curved portion 16 at the central portions 19 will not be uniform across the cross-sectional longitudinal direction DL, resulting in an increase in ventilation resistance of air passing through this portion. Therefore, the manufacturing method of the heat exchanger 1 here includes a twisting step S27 in which twisted portions 25 are formed in the flat tubes 22 of the curved portion 16 simultaneously with the bending step S26. In the flat tubes 22 of the curved portion 16, the locations where the twisted portions 25 are formed are portions where the fins 23 are not provided, between the portions of the flat tubes 22 at the ends in the extension direction that are penetrated and fixed to the second header 12 and the portions where the fins 23 are provided. By the twisting step S27, the flat tubes 22 adjacent in the direction along the curved shape of the curved portion 16 have consistent side surfaces at the central portions 19 that face each other along the cross-sectional longitudinal direction DL.

[0132] By configuring the manufacturing method of the heat exchanger 1 in this manner, the fins 23 provided on the flat tubes 22 of the curved portion 16 can be manufactured without deforming them, making it possible to manufacture a heat exchanger 1 that reduces the ventilation resistance of the curved portion 16.

[0133] The manufacturing method of the heat exchanger 1 representing the fifth modified example of the first embodiment includes a curved header creation process, a temporary assembly process, an insertion process, and a joining process. The curved header creation process is a process of creating a header having a curved portion 16 with a curved shape and partition walls 17 through which a plurality of flat tubes 22 can be passed and fixed. The temporary assembly process is a process of temporarily assembling a heat transfer section including a plurality of flat tubes 22 and a plurality of fins 23, each having a cross-sectional longitudinal direction DL that is the longitudinal direction of the outline shape of the cross section perpendicular to the extension direction DT. The insertion process is a process of inserting the plurality of flat tubes 22 of the heat transfer section so that they penetrate the partition walls 17 of the header. The joining process is a process of joining the contacting portions of the flat tubes 22 and the through holes 13 formed in the insertion process to create a flat plate-shaped assembly.

[0134] 33 is a flowchart showing a manufacturing method of the heat exchanger 1 according to the fifth modification of the first embodiment. The manufacturing method here includes a curved header manufacturing step S11, a temporary assembly step S12, an insertion step S13, and a joining step S14. The curved header manufacturing step S11 and the temporary assembly step S12 can be performed simultaneously in parallel.

[0135] The curved header creation step S11 is a step of creating a curved header such as the second header 12 shown in FIG. 20 by forming a plurality of through holes 13 aligned in the longitudinal direction on the upper surface of a hollow rod-shaped object having a curved portion 16 with a curved shape, through which flat tubes 22 can be passed and fixed. Note that the curved header creation step S11 may also be a step of creating a curved header by providing a plurality of through holes 13 in a hollow rod-shaped object and then forming a curved portion 16. Alternatively, the curved header creation step S11 may be a step of forming a plurality of through holes 13 aligned in a plate-shaped member having a curved shape that forms the upper surface, and providing a member that becomes a partition wall 17 that forms a hollow space that communicates with the through holes 13 on the lower surface of this plate-shaped member.

[0136] The temporary assembly step S12 is a step of arranging fins 23 between flat tubes 22 arranged with the cross-sectional longitudinal direction DL aligned, and joining the contacting portions of the flat tubes 22 and the fins 23 to create a temporary assembly 30. In the temporary assembly 30, the flat tubes 22 and the fins 23 are joined by, for example, brazing using a continuous furnace or adhesive joining using an adhesive with high thermal conductivity. The temporary assembly 30 is composed of a flat-plate-shaped first temporary assembly 30a in which the flat tubes 22 are inserted into the first straight portion 14, a flat-plate-shaped second temporary assembly 30b in which the flat tubes 22 are inserted into the second straight portion 15, and a flat-plate-shaped third temporary assembly 30c in which the flat tubes 22 are inserted into the curved portion 16.

[0137] In the insertion step S13, the flat tubes 22 of the temporary assembly 30 created in the temporary assembly step S12 are inserted into the header created in the curved header creation step S11. In this example, in the insertion step S3, the second header 12 is placed on a horizontal stage ST with the surface with the through holes 13 facing upward, and the flat tubes 22 of the temporary assembly 30 are inserted into the through holes 13. Here, the flat tubes 22 of the first temporary assembly 30a are inserted into the through holes 13 of the first straight portion 14, the flat tubes 22 of the second temporary assembly 30b are inserted into the through holes 13 of the second straight portion 15, and the flat tubes 22 of the third temporary assembly 30c are inserted into the through holes 13 of the curved portion 16.

[0138] 27 shows the insertion step S13 over time in the order of (a), (b), and (c). In the insertion step S13, first, the flat tube 22 moves laterally from the outer circumferential side (left side of the drawing) of the second header 12 toward the inner circumferential side (right side of the drawing) along the longitudinal direction of the cross-sectional shape of the through hole 13 on the top surface of the second header 12. Thereafter, the flat tube 22 is fixed, and the second header 12 moves vertically in the up-down direction, which is the extension direction DT of the flat tube 22. During this lateral movement, the flat tube 22 is inserted into the cutout portion 18 from one end in the cross-sectional longitudinal direction DL (right side of the drawing), and then moves through the through hole 13 in the cross-sectional longitudinal direction DL.

[0139] In this case, the insertion step S13 of the manufacturing method of the heat exchanger 1 may be a step of inserting the flat tubes 22 of the temporary assembly 30 from the opening direction of the through hole 13. In this case, it is preferable that the header does not have the cutout portion 18 having a shape continuous with the through hole 13.

[0140] In the joining step S14, the flat tubes 22 inserted into the header of the temporary assembly 30 in the insertion step S13 are joined to the header. In this example, the joining method between the header and the flat tubes 22, and between the flat tubes 22 and the fins 23 in the joining step S14 is preferably a method that does not use a continuous furnace, such as high-frequency brazing or torch brazing.

[0141] By configuring the manufacturing method for the heat exchanger 1 in this manner, the fins 23 provided on the flat tubes 22 in the curved portion 16 do not deform, making it possible to manufacture a heat exchanger 1 that reduces the ventilation resistance of the curved portion 16. Furthermore, when the insertion step S13 is a step of inserting the flat tubes 22 from the cutout portions 18 into the through holes 13 by moving them laterally, the flat tubes 22 of the heat transfer portion 21 are inserted reliably, making it possible to increase the yield of the heat exchanger 1 in the manufacturing process. This is particularly effective for a heat exchanger 1 having the through holes 13 in the curved portion 16 that are deformed when the header is curved.

[0142] Embodiment 2 A heat exchanger 1 of a second embodiment will be described with reference to Fig. 34. The heat exchanger 1 of the first embodiment includes partition walls 17 whose cross-sectional shape perpendicular to the direction along the curved shape of the curved portion 16 of the second header 12 does not have a distribution in thickness. In the heat exchanger 1 of the present embodiment, either or both of the inner and outer peripheral sides of the partition walls 17 have a distribution in thickness that includes thick portions and thin portions.

[0143] The heat exchanger 1 of this embodiment has the same overall shape as the heat exchanger 1 of the first embodiment shown in Fig. 2, is housed in the housing 2 as shown in Fig. 1, and includes a second header 12 having a curved portion 16 with the curved shape shown in Fig. 3. Note that in the second header 12 shown in Fig. 3, the longitudinal directions of the cross-sectional shape at the top surfaces of the through holes 13 of the curved portion 16 are all parallel, but in the header used in this embodiment, this portion does not have to be parallel. Also, in the header used in this embodiment, the spacing between the side surfaces of at least two adjacent flat tubes 22 facing each other in the direction along the curved shape of the curved portion 16 does not have to be constant along the cross-sectional longitudinal direction DL.

[0144] FIG. 34 is a cross-sectional view of the second header 12 of the heat exchanger 1 according to this embodiment taken along the cross section VV. The cross section VV here is located at the same position as the cross section VV shown in FIG. 3. In this embodiment, the same reference numerals as those used in the first embodiment indicate the same or corresponding parts. In this figure, the cross-sectional shape perpendicular to the direction along the curved shape of the curved portion 16 of the second header 12 used in this embodiment has a distribution in the thickness of the partition walls 17. This distribution of the thickness of the partition walls 17 is such that the partition walls 17 on the inner circumferential side (the right side in the figure) and the outer circumferential side (the left side in the figure) of the curved portion 16 alternate between portions with a minimum thickness TS and portions with a maximum thickness TL.

[0145] The thickness distribution of the partition walls 17 on the side surfaces of the header used in this embodiment may be on either the inner or outer circumferential side. The cross-sectional shape of the header used in this embodiment at cross section VV may be triangular as shown in Fig. 35, or pentagonal as shown in Fig. 36, or may be any other shape.

[0146] By providing a thickness distribution in the partition walls 17 on the side surfaces of the curved portion 16, the portion with the minimum thickness TS becomes a portion with lower rigidity than the portion with the maximum thickness TL. In this way, when the curved portion 16 deforms from a linear shape to a curved shape during the header manufacturing process, a portion with lower rigidity can be intentionally provided, which makes it possible to mitigate deformation of the through hole 13 in the curved portion 16.

[0147] By providing a distribution in the thickness of the partition walls 17 on the sides of the curved portion 16 in this way, deformation of the through holes 13 when forming the curved portion 16 is suppressed, and the insertion of the flat tubes 22 into the through holes 13 and the joining between the through holes 13 and the flat tubes 22 are more reliable. This also makes it possible to improve the yield of header material.

[0148] Variation 6. Fig. 37 is a top view of the second header 12 of the heat exchanger 1 showing a modified example of the present embodiment. Fig. 38 is a cross-sectional view of the second header 12 of the heat exchanger 1 showing a modified example of the present embodiment, taken at cross section YY, which is a cross section perpendicular to the direction along the curved shape and includes the through-hole 13 of the curved portion 16. The cross section YY here is at the same position as the cross section YY shown in Fig. 37.

[0149] The second header 12 used in this modified example has a cross-sectional shape perpendicular to the curved shape, including the through hole 13 of the curved portion 16, in which the thickness of the partition 17 on the outer side is greatest at the end on the side having the through hole 13 in the direction in which the through hole 13 opens. In Figure 37, the curved portion 16 has six through holes 13, and of these, four through holes 13, excluding the two at both ends in the direction along the curved shape, have protruding contours on the outer periphery in the longitudinal direction of the shape on the top surface. In Figure 38, the through holes 13 are provided on the upper surfaces of the partition walls 17 of the second header 12. The partition wall 17 on the outer circumferential side (left side in the figure) has a minimum thickness TS and a maximum thickness TL at its upper end. The portion with this maximum thickness TL is the second portion from the right in Figure 37, which is the protruding portion of the outer circumferential side profile. In addition, in the cross section YY of the second header 12, the partition walls 17 on the outer circumferential and inner circumferential side surfaces have a thickness distribution in which portions with thicknesses greater than the minimum thickness TS and smaller than the maximum thickness TL alternate with portions with minimum thickness TS.

[0150] The number of through holes 13 provided in the curved portion 16 is not limited to 6. Furthermore, the number of protruding portions on the outer periphery side of the curved portion 16 may be at least one.

[0151] By making the thickness of the portion of curved portion 16 that forms the contour of the outer periphery of through hole 13 thicker than the other portions, the rigidity of this portion is increased compared to the other portions. Thus, when curved portion 16 is deformed from a linear shape to a curved shape during the header manufacturing process, it is possible to reduce the elongation of the outer periphery of through hole 13 and suppress the deformation of through hole 13 from a rectangular shape to a sector shape.

[0152] 38, the cross section YY of the second header 12 has a thickness distribution in which the partition walls 17 on the outer and inner side surfaces have portions with thicknesses greater than the minimum thickness TS and smaller than the maximum thickness TL, alternating with portions with thicknesses greater than the minimum thickness TS. Note that in this modified example, the partition walls 17 on the side surfaces do not need to have such a thickness distribution.

[0153] By providing a distribution in the thickness of the partition walls 17 on the sides of the curved portion 16 in this way, deformation of the through holes 13 when forming the curved portion 16 is suppressed, and the insertion of the flat tubes 22 into the through holes 13 and the joining between the through holes 13 and the flat tubes 22 are more reliable. This also makes it possible to improve the yield of header material.

[0154] Variation 7. Figure 39 is a cross-sectional view of the second header 12 used in this modification at cross section VV, which is a cross section perpendicular to the longitudinal direction of the second straight section 15. Cross section VV here is located at the same position as cross section VV shown in Figure 3. In the heat exchanger 1 of this modification, the thickness of the partition walls 17 on the inner and outer circumferential side surfaces in a cross section perpendicular to the direction along the curved shape of the curved section 16 of the header has a distribution in which the thickest part is closer to the side surface having the through holes 13 than the thinnest part.

[0155] In the figure, the inner peripheral side (right side of the drawing) and outer peripheral side (left side of the drawing) of the partition walls 17 of the second header 12 have a minimum thickness TS at the bottom and a maximum thickness TL at the top. The second header 12 has through holes 13 on its top surface. Therefore, in the figure, the partition walls 17 on the inner peripheral side and outer peripheral side have a thickness distribution in which the thickest parts are closer to the side surface having the through holes 13 (the top surface in the figure) than the thinnest parts.

[0156] By making the side surface of curved portion 16 (the upper surface in this figure) that includes through hole 13 thicker than the other portions, the rigidity of this portion is increased compared to the other portions. Thus, when curved portion 16 is deformed from a linear shape to a curved shape during the header manufacturing process, it is possible to reduce the elongation of the outer periphery of through hole 13 and suppress the deformation of through hole 13 from a rectangular shape to a sector shape.

[0157] By providing a distribution in the thickness of the partition walls 17 on the sides of the curved portion 16 in this way, deformation of the through holes 13 when forming the curved portion 16 is suppressed, and the insertion of the flat tubes 22 into the through holes 13 and the joining between the through holes 13 and the flat tubes 22 are more reliable. This also makes it possible to improve the yield of header material.

[0158] Although the heat exchanger 1 of the present disclosure has been exemplified as having an L-shaped cross section including the first straight portion 14, the second straight portion 15, and the curved portion 16, it is sufficient that the heat exchanger has a curved shape of the curved portion 16. For example, the heat exchanger may have a U-shaped cross section including two curved portions 16 between three straight portions, an O-shaped cross section including three curved portions 16 between four straight portions, or a C-shaped cross section with no straight portions. [Explanation of symbols]

[0159] 1 heat exchanger, 11 first header, 12 second header, 13 through hole, 16 curved portion, 17 partition wall, 18 cutout portion, 19 center portion, 22 flat tube, 23 fin, 25 twisted portion, 26 air shielding member, 27 convex portion, 42 fin pattern, DL cross-sectional longitudinal direction, DT flat tube extension direction, HF fin height, O curvature center, S1 header creation process, S2 temporary assembly process, S3 insertion process, S4 joining process, S5 bending process, S11 curved header creation process, S12 temporary assembly process, S13 insertion process, S14 joining process, S21 header creation process, S22 first twisting process, S23 temporary assembly process, S24 insertion process, S25 joining process, S26 bending process, S27 second twisting process, S31 Header creation process, S32 temporary assembly process, S33 insertion process, S34 joining process, S35 bending process, S36 twisting process, WF fin width

Claims

1. a header having a curved portion with a curved shape; a plurality of flat tubes that penetrate and are fixed to the partition walls of the header, and whose outer surfaces act as heat transfer surfaces for the gas; fins provided on the outer surface of the flat tube; Equipped with If the longitudinal direction of the cross-sectional contour shape perpendicular to the extension direction of the flat tube is defined as the cross-sectional longitudinal direction, At least two of the flat tubes adjacent to each other in a direction along the curved shape provided in the curved portion have a constant distance between their opposing side surfaces along the longitudinal direction of the cross section, and the distance between the side walls of the gas flow path formed by the opposing side surfaces is constant. heat exchanger.

2. The plurality of flat tubes guide water by their own weight along the surface in the direction of extension. The heat exchanger of claim 1 .

3. The curved portion is The header is provided at a corner between two straight line portions that extend in different directions along the outline of a rectangular housing that accommodates the header. The heat exchanger of claim 1 .

4. All the fins are corrugated fins, have the same fin width, the same fin height, and the same fin pattern. The heat exchanger of claim 1 .

5. All of the fins provided on the curved portion have a straight line connecting their ends on the outer periphery, which is the side farthest from the center of curvature of the curved shape. The heat exchanger of claim 1 .

6. All of the flat tubes provided in the curved portion have a line connecting their ends on the outer circumferential side, which is the side farther from the center of curvature of the curved shape, that is, a straight line. The heat exchanger of claim 1 .

7. At least two of the flat tubes are provided adjacent to each other in a direction along the curved shape so that the distance between the side surfaces facing each other in the curved portion is constant along the longitudinal direction of the cross section, and include a tube having a twist between a central portion in the extension direction and a portion joined to the header. The heat exchanger of claim 1 .

8. The twisted portion of the flat tube is defined as a twisted portion, and the angle between the longitudinal direction of the cross section at one end of the twisted portion in the extension direction and the longitudinal direction of the cross section at the other end is defined as a twist angle. The flat tubes each having the twisted portion provided at the curved portion have a distance between one end of the fin closest to the twisted portion and a portion joined to the header that increases in order of the twist angle.

8. The heat exchanger of claim 7.

9. An air shielding member having a greater airflow resistance than the fins is provided between the header and the fins.

9. The heat exchanger of claim 8.

10. The through-holes, which are provided in the partition wall of the curved portion and into which the flat tubes are inserted and fixed, have a shape that is continuous with a notch portion that is provided in a side surface of the header and that is located on the outer circumferential side of the curved shape in the longitudinal direction in a cross-sectional shape perpendicular to the opening direction. The heat exchanger of claim 1 .

11. The flat tube has a protrusion having a shape that closes the notch when inserted into the through hole. The heat exchanger of claim 10.

12. a header having a curved portion with a curved shape; a plurality of flat tubes that penetrate and are fixed to the partition wall of the header; fins provided on the outer surface of the flat tube; Equipped with If the side closer to the center of curvature of the curved shape is the inner circumferential side and the side farther from it is the outer circumferential side, At least one of the innermost and outermost side surfaces of the curved shape in a cross section of the curved portion perpendicular to the extending direction of the header has a thickness distribution that alternates between thick and thin portions. heat exchanger.

13. a header having a curved portion with a curved shape; a plurality of flat tubes that penetrate and are fixed to the partition wall of the header; fins provided on the outer surface of the flat tube; Equipped with If the side farther from the center of curvature of the curved shape is defined as the outer circumferential side, In a cross section perpendicular to the direction along the curved shape of the header including the through holes provided in the curved portion through which the flat tubes pass, the thickness of the partition wall on the outer periphery is greatest at the end on the side having the through holes in the direction in which the through holes open. heat exchanger.

14. a header having a curved portion with a curved shape; a plurality of flat tubes that penetrate and are fixed to the partition wall of the header; fins provided on the outer surface of the flat tube; Equipped with If the side closer to the center of curvature of the curved shape is the inner circumferential side and the side farther from the center of curvature is the outer circumferential side, The partition wall on at least one side surface on an inner circumferential side and an outer circumferential side of the curved shape in a cross section of the curved portion perpendicular to a direction along the curved shape has a wall thickness distribution in which the thickest portion is closer to the partition wall through which the flat tube passes and is fixed than the thinnest portion. heat exchanger.

15. a header fabrication process for fabricating a linear header in which a plurality of through holes are provided in the partition wall so that the distance between adjacent through holes at both ends in the longitudinal direction of the cross section perpendicular to the opening direction is smaller than that at one end; a temporary assembly process for preparing a temporary assembly of a heat transfer section including a plurality of flat tubes and a plurality of fins, the cross-sectional longitudinal direction of which is the longitudinal direction of a cross-sectional outline shape perpendicular to the extension direction; an insertion step of inserting the flat tube of the temporary assembly prepared in the temporary assembly step into the through hole of the header; a joining step of joining a contact portion between the through hole formed in the insertion step and the flat tube to form a flat plate-like assembly; a bending process of providing a curved shape to the header of the assembly created in the joining process so that the side where the distance between both ends of the cross-sectional shape of the adjacent through holes in the longitudinal direction is narrower is the outer circumferential side, and forming curved portions of the flat tubes adjacent in a direction along the curved shape so that the distance between mutually opposing side surfaces is constant over the longitudinal direction of the cross section; A method for manufacturing a heat exchanger having the above structure.

16. From the start to the completion of the bending process, A twisting step of forming a twisted portion, which is a portion where a twist is provided at an end of the curved portion in the extension direction of the flat tube, is included. A method for manufacturing the heat exchanger according to claim 15.

17. A method for manufacturing a heat exchanger including a curved header having a curved portion with a curved shape, the curved header having through holes in a partition wall of the curved portion, the through holes having a constant interval between adjacent through holes at both ends in the longitudinal direction of a cross section perpendicular to an opening direction, and flat tubes whose outer surfaces act as heat transfer surfaces with respect to a gas, the method comprising: a curved header creating step of creating the curved header; a preliminary assembly process for preparing a preliminary assembly of a heat transfer section including a plurality of flat tubes and a plurality of fins, the cross-sectional longitudinal direction of which is the longitudinal direction of the outline of the cross section perpendicular to the extension direction; an inserting step of inserting the flat tube of the temporary assembly prepared in the temporary assembling step into the through hole of the curved header prepared in the curved header preparing step; a joining process for joining portions of the flat tubes in contact with at least two of the through holes of the curved portion formed by the inserting process so that the distance between the opposing side surfaces of the flat tubes is constant along the longitudinal direction of the cross section and the distance between the side walls of the gas flow path formed by the opposing side surfaces is constant; A method for manufacturing a heat exchanger having the above structure.

18. The curved header manufacturing process includes: providing a notch portion in the partition wall of the curved portion, the notch portion being located on an outer circumferential side of the curved shape in a longitudinal direction in a cross section perpendicular to a direction in which the through hole opens, and having a shape continuous with the through hole, The inserting step includes: and inserting the flat tube into the notch portion from one end in the longitudinal direction of the cross section, and then moving the flat tube through the through hole in the longitudinal direction of the cross section. A method for manufacturing the heat exchanger according to claim 17.

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